Systems and methods for safe compliant insertion and hybrid force/motion telemanipulation of continuum robots

Information

  • Patent Grant
  • 9539726
  • Patent Number
    9,539,726
  • Date Filed
    Tuesday, May 6, 2014
    10 years ago
  • Date Issued
    Tuesday, January 10, 2017
    7 years ago
Abstract
Methods and systems are described for controlling movement of a continuum robot that includes a plurality of independently controlled segments along the length of the continuum robot. The continuum robot is inserted into a cavity of unknown dimensions or shape. A plurality of forces acting upon the continuum robot by the surrounding cavity are estimated. A positioning command indicating a desired movement of the distal end of the continuum robot is received from a manipulator control. The desired movement is augmented based, at least in part, on the estimated plurality of forces acting on the continuum robot such that movement is restricted to within safe boundaries of the surrounding cavity. The positioning of the continuum robot is then adjusted based on the augmented desired movement.
Description
FIELD OF THE INVENTION

The present invention relates to systems and methods of controlling the position and pose of multi-segment continuum robots. More specifically, the present invention relates to systems and methods of compliant insertion of a continuum robot into a cavity of unknown size, dimensions, and structure.


BACKGROUND OF THE INVENTION

Multi-segment continuum robots provide for snake-like movement and positioning by deformation of internal structures of the robotic mechanisms as opposed to the relative deformation of individual rigid links. As such, continuum robots can be used to extend deeper into cavities to perform functions including, for example, search and rescue in disaster relief, nuclear handling, and minimally invasive surgical procedures. However, adoption of continuum robots has been limited due to a lack of controls methods to prevent damage to the robotic structure and the environment when the device is inserted into a cavity of unknown dimensions. During insertion into a complex environment, such as a surgical or disaster site, continuum robots must interact safely while being subject to a multitude of unknown contact sites along the robot arm length.


Passive compliance techniques have been proposed to achieve safe interaction without the need for additional sensing and complex control. Passively compliant structures contain flexible members which comply with environment interaction forces without explicit compliant control. Though these systems have shown promise in providing a measure of safety, they suffer from a number of significant disadvantages for exploration and intervention in unstructured environments. By the very nature of their design, passive compliant systems are limited in their accuracy and the magnitude of forces that can be applied during environment interaction. Conversely, the measure of safety provided by passive compliance is limited by the flexibility of the system. Additionally, the compliance adds uncertainty and modeling difficulties that degrade trajectory tracking performance. Thus, a need exists for active compliant instrumentation that can safely interact with the surrounding environment while maintaining manipulation precision and delivering adequate forces for executing manipulation tasks.


SUMMARY OF THE INVENTION

The systems and methods described below allow a continuum robot system to adapt to the shape of a multi-segmented continuum robot structure to thereby adapt to the previously unknown dimensions of a cavity. The shape and position of the individual segments of the continuum robot are continually adjusted as the continuum robot is advanced further into the cavity.


International Publication No. WO 2013/158978 to Simaan et al., the entirety of which is incorporated herein by reference, describes a method of compliant insertion of a continuum robot. The continuum robot includes a plurality of independently controlled segments along a length of the continuum robot. The continuum robot is inserted into a cavity of unknown dimensions. A plurality of forces acting on the continuum robot are determined. The plurality of forces includes a force acting on each of the plurality of segments along the length of the continuum robot. Each force of the plurality of forces includes a magnitude and a direction. These forces result in a generalized force that captures the statics of the robot as described in its configuration space (a space describing the shape of each segment by two configuration space angles per a segment). Each determined generalized force is compared to a respective expected generalized force for each of the plurality of segments. The expected force for each segment is determined based on the position of the continuum robot. The position of each segment of the continuum robot is adjusted based on a difference between the determined generalized force and the expected generalized force for the segment. In some embodiments, the method further includes repeating the acts of determining the plurality of forces, comparing each determined force to a respective expected force, and adjusting the position of each segment as the continuum robot is advanced further into the cavity.


In another embodiment, the invention provides a controller for compliant insertion of a continuum robot into a cavity of unknown dimensions. The continuum robot includes a plurality of independently controlled segments along the length of the continuum robot. The controller includes a processor and memory storing instructions that are executable by the processor. The controller is configured to determine a plurality of forces acting on the continuum robot. The plurality of forces includes a generalized force acting on each of the plurality of segments along the length of the continuum robot. Each generalized force includes a magnitude and a direction. Each determined generalized force is then compared to a respective expected generalized force for each of the plurality of segments. The expected generalized force is determined based on the position of the continuum robot. The controller adjusts the position of each segment based on the difference between the determined generalized force and the expected generalized force for each of the plurality of segments.


In another embodiment, the invention provides a robotic system including a continuum robot, a plurality of actuators, and a controller. The continuum robot includes a plurality of independently controlled segments along the length of the continuum robot and a plurality of back-bone structures extending through the continuum robot. Each actuator is connected to a different one of the plurality of back-bone structures and advances or retracts the back-bone structure to control the shape and end effector position of the continuum robot. The controller includes a processor and a memory. The controller determines a plurality of forces acting on the continuum robot based on forces exerted on the plurality of back-bone structures by the plurality of actuators. The determined forces include a generalized force acting on each of the plurality of segments along the length of the continuum robot. Each generalized force includes a magnitude and a direction. The controller compares each determined generalized force to a respective expected generalized force for each of the plurality of segments. The expected generalized force is determined based on the position of the continuum robot. The position of each segment is adjusted based on the difference between the determined generalized force and the expected generalized force for each segment. The acts of determining the plurality of forces, comparing the generalized forces to a respective expected generalized force, and adjusting the position of each segment are repeated as the continuum robot is advanced into the cavity.


In some embodiments, compliant motion control of the continuum robot is provided by mapping generalized forces into a configuration space of a robot. Support vector regression techniques are used to provide sparse interpolation to estimate and cancel out effects of uncertainty in the generalized forces due to friction and uncertainty in material properties.


In some embodiments, the compliant motion control methods are used to operate rapidly deployable handheld robotic devices that are inserted into the human anatomy for surgical operations such as trans-urethral bladder resection, trans-nasal surgery, and frontal sinus exploration/surgery. In some embodiments, the methods are also used to provide impedance control of continuum robots and to enable a method for bracing the continuum robot against the anatomical features inside the cavity once contact has been localized and detected. Bracing techniques provide increased stability and increased accuracy for operations performed by a tool positioned at the distal end of the continuum robot. Collaborative telemanipulation algorithms can be implemented to work with the compliant motion control methods to reduce the telemanipulation burden of high degree-of-freedom (DoF) surgical slave devices.


Continuum robots with compliant insertion functionality can be used, among other things, to perform a minimally invasive surgery (MIS) of the throat which typically requires full anesthesia and use of a laryngoscope. Additional examples of potential applications include frontal sinus exploration surgery and office-based sinus surgery treatment and monitoring of disease progression. This technology is can also be used, for example, for micro-surgical function restoration of paralyzed vocal cords, which requires control of the location and amount of material to inject inside the paralyzed vocal cord. Currently, surgeons guess the amount of material and adjust accordingly during a follow-up surgery (assuming they do not overfill the vocal cord). By avoiding the use of full anesthesia, cost of operation is reduced and surgeons can get feedback about surgical outcomes during the procedure. Relevance is also found in injection site targeting that currently pairs a trans-dermal injection with a microscope for visualizing the anatomy.


In one embodiment, the invention provides a method of controlling movement of a continuum robot that includes a plurality of independently controlled segments along the length of the continuum robot. The continuum robot is inserted into a cavity of unknown dimensions or shape. A plurality of forces acting upon the continuum robot by the surrounding cavity are estimated. A positioning command indicating a desired movement of the distal end of the continuum robot is received from a manipulator control. The desired movement is augmented based, at least in part, on the estimated plurality of forces acting on the continuum robot such that movement is restricted to within safe boundaries of the surrounding cavity. The positioning of the continuum robot is then adjusted based on the augmented desired movement.


In some such embodiments, the desired movement includes an advancement of the continuum robot through a nasal cavity towards a surgical site in the throat of a patient. The desired movement is augmented by determining an appropriate safe pose for the continuum robot as the distal end is advanced further into the cavity.


In another embodiment, the invention provides a method of controlling positioning of a continuum robot. A set of allowable motions and a set of allowable forces are determines for a continuum robot based, in some cases, on the current position and surroundings of the continuum robot. The set of allowable motions and the set of allowable forces are then projected as projection matrices into a joint space corresponding to a manipulator control. Motion commands received through the manipulator control are translated into one or more task-specific wrenches and then into a joint-torque vector command. The position of the continuum robot is adjusted based on the joint-torque vector command using a joint-space PID controller.


Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a perspective view of a multiple-segment continuum robot.



FIG. 2 is a perspective view of a single segment of the continuum robot of FIG. 1.



FIG. 3 is a block diagram of a controller for positioning the continuum robot of FIG. 1.



FIG. 4 is a perspective view of the continuum robot of FIG. 1 being inserted into the nasal passage of a human head.



FIG. 5 is a flowchart illustrating a method of adjusting the position of the continuum robot of FIG. 1 as the continuum robot is inserted into a cavity of unknown size and dimensions.



FIG. 6 is a flowchart illustrating a method of adjusting the position of a single segment of the multiple-segment continuum robot of FIG. 1 as the continuum robot is inserted into a cavity of unknown size and dimension.



FIG. 7 is a stiffness model for segment of the continuum robot of FIG. 1 with multiple back-bone structures.



FIG. 8 is a graph of sample training and estimation data for the uncertainty parameters in a multi-segment robot.



FIG. 9 is a graph of training and estimation data similar to the data provided in FIG. 8.



FIG. 10 is a functional block diagram of the operation of a controller providing for compliant insertion of the continuum robot of FIG. 1.



FIG. 11 is a perspective view of an experimental system for analyzing the sensitivity of a continuum robot utilizing compliant motion control.



FIG. 12 is a graph illustrating poses of the continuum robot during sensitivity analysis of the compliant motion controller using the experimental system of FIG. 11.



FIG. 13 is a table providing experimental data recording during sensitivity analysis of the compliant motion controller using the experimental system of FIG. 11.



FIG. 14 is a graph illustrating measured and theoretical minimum forces required for compliant motion during sensitivity analysis of the compliant motion controller using the experimental system of FIG. 11.



FIG. 15 is a table providing mean pose error and standard deviation of the nominal kinematics from magnetic sensor measurements during sensitivity analysis of the compliant motion controller using the experimental system of FIG. 11.



FIG. 16 is a series of images showing compliant insertion of a continuum robot into a cavity of unknown size and shape.



FIG. 17 is a series of graphs illustrating reaction data for the compliant insertion of FIG. 16.



FIGS. 18A, 18B, and 18C are cutaway views of a continuum robot being positioned at a location in the throat of a patient through trans-nasal access.



FIG. 19 is an elevation view of an actuation unit for a continuum robot.



FIG. 20 is a perspective view of a posed continuum robot.



FIG. 21 is a functional block diagram of a hybrid control system for manipulation of the continuum robot.



FIG. 22A is a perspective view of a posed continuum robot.



FIG. 22B is a perspective view of a posed manipulator control corresponding to the posed position of the continuum robot in FIG. 21A.



FIG. 22C is a view of the distal end of the continuum robot as seen from the fiberscope.



FIG. 23 is a functional block diagram of a hybrid motion/force control system for manipulation of a rigid-link robotic system.



FIG. 24 is a functional block diagram of a hybrid motion/force control system for manipulation of a multi-backbone continuum robot.



FIGS. 25A and 25 B are graphs of wrench and twist screw bases corresponding with a frictionless point contact.



FIG. 26A is a perspective view of a posed continuum robot.



FIG. 26B is a side view of the posed continuum robot of FIG. 26A.



FIG. 27 is a table of kinematic and static parameters of the continuum robot of FIG. 26A.



FIG. 28 is a graph of error between expected and actual actuation force on a backbone of the continuum robot of FIG. 26A as a function of bending angle.



FIG. 29 is a graph of error between expected and actual actuation force on a second backbone of the continuum robot of FIG. 26A as a function of bending angle.



FIG. 30 is a graph of error between the expected and actual actuation force on a third backbone of the continuum robot of FIG. 26A as a function of bending angle.



FIG. 31 is an elevation view of a continuum robot during force regulation testing.



FIG. 32 is a table of experimental results of force regulation in the x direction for three bend angles and three force magnitudes.



FIG. 33 is a table of experimental results of force regulation in the y direction for three bend angles.



FIGS. 34A, 34B, and 34C are graphs of force step response on a silicon block in the x direction at a bend angle of 80° for three different forces.



FIGS. 35A, 35B, and 35 C are graphs of force step response on a silicon block in the x direction at a bend angle of 60° for three different forces.



FIGS. 36A, 36B, and 36C are graphs of force step response on a silicon block in the x direction at a bend angle of 40° for three different forces.



FIGS. 37A, 37B, and 37C are graphs of force step response on a silicon block in the y direction for three different starting bend angles 80°, 60°, and 40°.



FIG. 38A is a top view of an continuum robot performing shape estimation.



FIG. 38B is an elevation view of the continuum robot of FIG. 38A performing the shape estimation.



FIG. 39 is an overhead view of a probe used for a manual scan of phantom tissue.



FIG. 40 is a series of three graphs illustrating the shape of a structure as estimated using the continuum robot of FIG. 38A from a side view, a front view, and a top view.



FIG. 41 is a series of three graphs illustrating the actual, ground truth shape of the structure measured by the continuum robot in FIG. 38A from a side view, a front view, and a top view.



FIG. 42 is a series of three graphs illustrating the error between the estimated shape and the actual shape measured by the continuum robot in FIG. 38A from a side view, a front view, and a top view.



FIG. 43 is a top view of a continuum robot being used to localize a blood vessel.



FIG. 44 is a graph illustrating the surface as estimated by the continuum robot in FIG. 43 at a first force.



FIG. 45 is a graph illustrating the surface as estimated by the continuum robot in FIG. 43 at a second, greater force.



FIG. 46 is a stiffness map of the surface as estimated by the continuum robot in FIG. 43.





DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.



FIG. 1 illustrates a multiple-segment continuum robot 100 with multiple back-bone structures to control the movement and position of the continuum robot 100. The multiple-segment continuum robot 100 of FIG. 1 includes three independent segments 101, 102, and 103. However, other continuum robots may include more or fewer segments. In operation, a tool or other device would be extended through the continuum robot and would emerge at the distal end of the continuum robot (e.g., the open end of segment 103). The other labels and vectors illustrated in FIG. 1 are referred to below in describing the kinematics of the continuum robot.



FIG. 2 provides a more detailed view of a single segment 101 of the continuum robot 100. The continuum robot 100 includes a single central back-bone 121 and multiple secondary back-bones 123. Each segment 101 includes a base disc 125 at the proximate end of the segment and an end disc 127 at the distal end of the segment. A plurality of spacer discs 129 are positioned between the base disc 125 and the end disc 127. The secondary back-bones 123 are super elastic NiTi tubes circumferentially distributed around the central back-bone 121. The end disc 127 is attached to all of the back-bones 121, 123. The base disc 125 is connected only to the central backbone 121. The spacer discs 129 area separated by elastomeric spacers (not pictured) and float along the central backbone 121 while maintaining a fixed radial distance between the central backbone 121 and all secondary backbones 123. Using this arrangement, two degrees of freedom (DoF) per segment are controlled by pushing and pulling on the secondary backbones 123 to bend the segment in a circular arc.


The inset 131 of FIG. 2 illustrates a top view of the discs 125, 127, and 129. A single hole 133 is positioned at the center of each disc. The central backbone 121 extends through the hole 133. Each disc in this example also includes a plurality of holes 135 positioned around the circumference of the disc. The secondary backbones 123 extend through these holes 135. Each disc also includes one or more larger holes 137. Instruments such as, for example, grabbers, cameras, light sources, laser ablation tools, imaging probes (e.g. ultrasound or optical coherence tomography) can be extended through the continuum robot via these larger holes 137 and will emerge from the distal end of the continuum robot 100. As in FIG. 1, the additional labels and vectors illustrated in FIG. 2 are referred to below in describing the kinematics of the continuum robot.



FIG. 3 illustrates a control system for the continuum robot 101 of FIG. 1. The control system includes a controller 301 with a processor 303 and a memory 305. The memory 305 stores instructions that can be executed by the processor 303 to cause the controller to control the operation of the continuum robot. Multiple actuators 307, 309, 311 are connected to and operated by the controller 301. As described above, the actuators 307, 309, 311 each push and pull on one of the secondary backbones 123 of the continuum robot 100 to adjust the position and pose of the continuum robot 100.


A continuum robot 100 can be inserted into various cavities to reach a target location. Once the distal end of the continuum robot 100 is positioned at the target location, tools emerging from the distal end of the continuum robot 100 are used to perform operations. FIG. 4 illustrates an example of a continuum robot 100 inserted into the nasal passage of a human head 400. In this example, the target location for the distal end of the continuum robot is the upper sinuses. However, the exact dimensions and size of the nasal passages extending from the nose to the upper sinus may not be known. The compliant insertion methods described herein enable the continuum robot 100 to adapt its shape and position to comply with the shape of the nasal passages as the continuum robot 100 is advanced into the nasal passage. Although the examples described herein refer to a continuum robot being inserted into the nasal passage to reach an upper sinus, the methods and systems described herein also provide compliant motion control for other continuum robot applications such as minimally invasive surgery at other locations of the human body or larger applications such as search and rescue at disaster sites.



FIG. 5 describes a method of adjusting the position and shape of the continuum robot to adapt to the shape of the cavity in which it has been inserted. The continuum robot 100 is pushed further into the cavity to advance the position of the distal end (step 501). The forces exerted along the length of the continuum robot 100 are measured (step 503). In particular, each determined force indicates the generalized forces applied to the end disc 127 of each segment of the continuum robot. These measured forces include both the forces required to position the continuum robot in its current shape and external forces, or wrenches, applied to the continuum robot 100 by the surfaces of the cavity. The measured generalized forces along the length of the continuum robot are compared to expected generalized forces that would be detected on the continuum robot if it were positioned in its current shape without the presence of external wrenches (step 505). The positions of the continuum robot segments are then adjusted to minimize the difference between the measured generalized forces and the expected generalized forces (step 507). In other words, the shape of the continuum robot is adjusted to minimize the affect of external wrenches on the continuum robot structure along the length of the continuum robot 100.



FIG. 6 illustrates in further detail how the controller 301 adjusts a single segment of the continuum robot 100. The method illustrated in FIG. 6 is performed concurrently and repeatedly for each segment of the continuum robot 100 as it is inserted into the cavity. As the continuum robot 100 is advanced into the cavity (step 601), the controller measures the forces on each of the controlled secondary backbone structures 123 (step 603). The forces are measured at the actuator units and, again represent the forces required to position the continuum robot in its current position and external wrench applied to the continuum robot structure by the surfaces of the cavity. The controller further determines a generalized force applied to the end disc of each individual segment of the continuum robot (step 605). The determined generalized force is compared with an expected generalized force (step 607) to determine the magnitude and direction of the external wrench applied to the continuum robot at the end disc of each segment. If the difference between the measured generalized force and the expected generalized force (e.g., the magnitude of the wrench) is greater than a threshold, the controller determines the direction of the wrench (step 611) and adjusts the position of the segment accordingly (step 613). If the magnitude of the wrench does not exceed the threshold, the controller continues to monitor forces (step 603) without changing the position of the continuum robot. In some embodiments, the threshold applied in step 609 is adjusted in real-time during insertion of the continuum robot into the cavity to account for elastic cavity surfaces such as internal body tissues.


Once the continuum robot has been sufficiently inserted into the cavity and the distal end of the continuum robot has reached its target location, the same compliant insertion techniques can be used to brace the continuum robot against the surfaces of the cavity. Bracing the continuum robot provides additional stability and allows for more accurate placement and maneuvering of the tools emerging from the distal end of the continuum robot. To brace the continuum robot, the controller 301 adjusts the position of each segment of the continuum robot to increase the difference between the measured generalized force and the expected generalized force on each end disc 127. To prevent damage to the continuum robot structure, the controller 301 ensures that the difference between the expected generalized force and the measured generalized force (i.e., the magnitude of the wrench) does not exceed a defined threshold.


The following nomenclature is used to describe the kinematics of the continuum robot, the mathematical modeling, and the specific techniques used to map external wrenches to a generalize force to provide for compliant insertion:

    • Ai ith row of A
    • A[i] ith column of A
    • [A]ij Entry at the ith row and jth column of the matrix A
    • n Number of segments of the continuum robot
    • m Number of secondary backbones in each continuum segment
    • cα, sα Abbreviated form of the cosine and sine respectively where cα=cos α and sα=sin α
    • θ(k) Bending angle for an individual segment
    • δ(k) Bending plane angle for an individual segment
    • ψ(k) Configuration space vector for an individual segment, ψ(k)=[θ(k), δ(k)]T
    • ψa Augmented configuration space vector for the multi-segment continuum robot, ψa=[ψT(1), . . . , ψT(n)]T
    • ^u, ^v, ^w Unit basis vectors of an arbitrary coordinate frame such that [^u, ^v, ^w]=Iεcustom character3×3
    • {b(k)} Base frame of the kth segment
    • {g(k)} End frame of the kth segment
    • cPab Position vector pointing from point a (or the origin of frame {a}) to point b (or the origin of frame {b}) expressed in frame {c}
    • aRb Rotation matrix describing the orientation of frame {b} with respect to frame {a}
    • cvb/a Linear velocity of frame {b} with respect to frame {a}, expressed in frame {c}
    • cωb/a Angular velocity of frame {b} with respect to frame {a}, expressed in frame {c}
    • ctb/a Twist of frame {b} with respect to frame {a}, expressed in frame {c}: ctb/a=[cvTb/a, cωTb/a]T
    • Jqψ(k) A Jacobian matrix linearly mapping the configuration space velocities to joint velocities such q(k)=Jqψ(k)ψ(k)
    • Jvψ(k) A Jacobian matrix linearly mapping the configuration space velocities to linear velocities such that v=Jvψ(k) ψ(k)
    • Jωψ(k) A matrix linearly mapping of the configuration space velocities to angular velocities such that ω=Jωψ(k) ψ(k)
    • Jtψ(k) A linear mapping of the configuration space velocities to the twist such that






t
=



J

t






ψ


(
k
)






ψ

(
k
)







and






J

t






ψ

(
k
)





=

[




J

v






ψ

(
k
)









J

w






ψ

(
k
)







]








    • EY Young's elasticity modulus for the NiTi back-bones

    • I(k) Cross-sectional second moment of inertia of backbones of the kth segment

    • r Radius of the pitch circle along which the secondary backbones are circumferentially distributed around the primary backbone

    • T(k) Backbone actuation forces of an individual segment T(k)=[T1,(k), . . . , Tm,(k)]T

    • f(k) Generalized force for the kth individual segment

    • fa Augmented generalized force for the multi-segment continuum robot fa=[fT(1)), . . . , fT(n)]T

    • λ, ^λ Actual and estimated augmented generalized force errors

    • Kψ,(k) Configuration space stiffness for the kth individual segment

    • Kψa Configuration space stiffness for the multi-segment continuum robot

    • x Input feature vector to the Support Vector Regression (SVR)

    • N The number of training data for the SVR optimization

    • φ(·) High dimensional mapping of the input feature space of the support vectors in the SVR





The pose of the kth segment continuum robot (as illustrated in FIG. 2) is described in a set of generalized coordinates by a configuration space vector defined as

ψ(k)=[θ(k)(k)]T  (1)


where (·)(k) denotes a variable associated with the kth segment. θ(k) defines the bending angle of the segment measured from the plane defined by the base disk, {^ub(k), ^vb(k)}, and the direction normal to the end disk ^wg(k). δ(k) defines the orientation of the bending plane of the segment as measured from the plane to the ^ub(k) about ^wb(k).


The inverse kinematics of the segment relating the configuration space, ψ(k), to the joint space, q1,(k)=[q2,(k), qm,(k)]T, is given by

Lj,(k)=L(k)+qj,(k)=L(k)j,(k)θ(k).  (2)

where Lj,(k) is the length of the jth secondary backbone of the kth segment for j=1, . . . , m, L(k) is the length of the primary backbone of the kth segment, Δj,k=r cos δj,k; δj,(k)(k)+(j−1) (2π/m), and Θ(k)=θ(k)−π/2.


The instantaneous inverse kinematics can be described by differentiating (2) to yield

{dot over (q)}(k)=Jqψ(k){dot over (ψ)}(k)  (3)

where the Jacobian Jqψ(k) is given by










J

q






ψ


(
k
)




=

[




rc

σ

1
,

(
k
)








-
r







θ

(
k
)




s

σ

1
,

(
k
)


















rc

σ

m
,

(
k
)








-
r







θ

(
k
)




s

σ

m
,

(
k
)








]





(
4
)







The direct kinematics of the kth segment is given by the position b(k)Pb(k)g(k) and orientation b(k)Rg(k) of the segment end disk with respect to its base disk. For








θ

(
k
)




π
2


,





the kinematics takes the form










P


b

(
k
)




g

(
k
)







b

(
k
)



=



L

(
k
)



θ

(
k
)





[





c

σ

(
k
)





(


s

θ

(
k
)



-
1

)







-


s

σ

(
k
)





(


s

θ

(
k
)



-
1

)








-

c

θ

(
k
)







]






(
5
)







R

g

(
k
)






b

(
k
)



=




-

σ

(
k
)


[


w
^


x

]








-

θ

(
k
)


[


v
^


x

]








σ

(
k
)


[


w
^


x

]








(
6
)








where {circumflex over (ν)}=[0, 1, 0]T, ŵ=[0, 0, 1]T and the frames {g(k)} and {b(k)} are shown in FIG. 3. For








θ

(
k
)


=

π
2


,





the formulation singularity,







1

Θ

(
k
)



,
,





resolves to










P


b

(
k
)




g

(
k
)







b

(
k
)



=


[



0


0



L

(
k
)





]

T





(
7
)







R

b

(
k
)






b

(
k
)



=

I




3
×
3







(
8
)








By differentiating (5) and (6), the instantaneous direct kinematics takes the form











t

g

(
k
)






b

(
k
)



/

b

(
k
)



=


J

t






ψ

(
k
)







ψ
.


(
k
)







(
9
)








where, for








θ

(
k
)


=

π
2


,





the Jacobian Jrψ(k) is given by δ










J

t






ψ

(
k
)




=

[





Ls

δ

(
k
)








θ

(
k
)




c

θ

(
k
)




-

s

θ

(
k
)



+
1


θ

(
k
)

2








-

Ls

δ

(
k
)







s

θ

(
k
)




θ

(
k
)




-
1







Ls

δ

(
k
)








θ

(
k
)




c

θ

(
k
)




-

s

θ

(
k
)



+
1


θ

(
k
)

2







Lc

δ

(
k
)







s

θ

(
k
)



-
1


θ

(
k
)









L







θ


s







θ

(
k
)



+

c






θ

(
k
)





θ

(
k
)

2





0





-

s

δ

(
k
)








c

δ

(
k
)





c

θ

(
k
)









-

c

δ

(
k
)








-

s

δ

(
k
)






c

θ

(
k
)








0




-
1

+

-

s

θ

(
k
)








]





(
10
)








and for








θ

(
k
)


=

π
2


,





the formulation singularity,







1

θ

(
k
)



,





is resolved by applying l'Hôpital's rule, to yield










J

t






ψ

(
k
)




=


[





-

L
2




c

δ

(
k
)








L
2



s

δ

(
k
)






0



-

s

δ

(
k
)







-

c

δ

(
k
)






0




0


0


0


0


0


0



]

T





(
11
)








Using Euler beam bending analysis and neglecting gravitational potential energy, the total energy of the continuum robot is given by






U
=




k
-
1

n







U

(
k
)








where the potential elastic energy of the kth segment is given by










U

(
k
)


=




E
Y



I

(
k
)




θ

(
k
)

2


2



(


1

L

(
k
)



+




j
-=
1

m







1

l

j
,

(
k
)






)






(
12
)







The principle of virtual work and the energy expression (12) are used to obtain a statics model for the kth continuum segment as

Jqψ(k)TT(k)=∇U(k)−J(k)Twe,(k)  (13)

where τ(k) represents the actuation forces on the secondary backbones, ∇U(k) is the gradient of the potential energy, and ψe,(k) is the external wrench applied to the end disk of the kth continuum segment. The energy gradient ∇U(k) is calculated with respect to a virtual displacement in configuration space. Δψ(k)=[Δθ(k), Δδ(k)]T and is given by












U

(
k
)



=


E
Y



I

(
k
)






[






θ

(
k
)



L

(
k
)



+








j
=
1

m








θ

(
k
)



L

j
,

(
k
)





-






θ

(
k
)

2

2


r







j
=
1

m












c
σ



j

,

(
k
)



L

j


,

(
k
)



2




















θ

(
k
)

3

2


r





j
=
1

m












s
σ



j

,

(
k
)



L

j


,

(
k
)



2












]







(
14
)







The statics expression (13) projects both the actuation forces T(k) and perturbation wrench we,(k)w into the configuration space of the continuum segment, ψ(k) Thus, after projecting the wrench from three-dimensional Cartesian space, custom character6, into the configuration space, custom character2, the projected generalized force on the segment resides in the vector space controllable within the framework of the single-segment kinematics of equation (1). This projection eliminates the requirements for explicit determination of wrenches required by conventional compliance algorithms and casts the interaction force minimization problem into the configuration space of the continuum segment.


If the wrench acting on the end disk that is projected into the configuration space of the kth segment is defined as the generalized force vector

f(k)Jt,ψ(k)Twe(k)  (15)

Applying equation (13) to the generalized force expression, the ith row of the generalized force f(k) can be written as

fi=∇Ui−[JT]iT=∇Ui[J[i]]TT  (16)

where J[i] denotes the ith column of J.


For small perturbations from an equilibrium configuration, the stiffness of the individual continuum segment can be posed in the configuration space as

δf=Kψδψ  (17)

where the stiffness is given by the Jacobian of the generalized force with respect to configuration space perturbation. Thus, the elements of kψ are given by:













f
i





ψ
j



=



[

K
ψ

]

ij

=






ψ
j





[




U
i


-



[

J

q





ψ


[
I
]


]

T


T


]







(
18
)








The elements of the stiffness matrix (18) can be expanded as











[

K
ψ

]

ij

=



[

H
ψ

]

ij

-



[






ψ
j





(

j

q





ψ


[
i
]


)


]

T


T

-



[

J

q





ψ


[
i
]


]

T





T




ψ
j









(
19
)








The first term of the configuration space stiffness, Hψ is the Hessian of the elastic energy of the segment given by










H
ψ

=







2


U




θ
2









2


U




θ




β











2


U




δ




θ









2


U




δ
2










(
20
)








The individual elements of the Hessian, Hψ, are given by













2


U




θ
2



=


E
Y



I
[


1
L

+




I
=
1

m







1

L
i



-

2

r





θ





i
-
1

m













c


σ



i


L
i
2




+


θ
2



r
2






i
=
1

m








c

σ
i

2


L
i
3





]






(
21
)










2


U




θ




δ



=





2


U




δ




θ



=


E
Y



I
[




3


θ
2


2


r





i
=
1

m








s

σ
i



L
i
2




-


θ
3



r
2






i
=
1

m









s

σ
i




c

σ
i




L
i
3





]







(
22
)










2


U




δ
2



=


E
Y



I
[




θ
3

2


r





i
=
1

m








c

σ
i



L
i
2




+


θ
4



r
2






i
=
1

m








s

σ
i

2


L
i
3





]






(
23
)








The second term of equation (19) expands to















ψ
1





(

J

q





ψ

1

)


=

0



m






(
24
)












ψ
1





(

J

q





ψ

2

)


=







ψ
2





(

J

q





ψ

1

)


=

-


r


[


s

σ
1


,





,

s

σ
m



]


T







(
25
)












ψ






2




(

J

q





ψ

2

)


=


-
r








θ


[


c

σ
1


,





,

c

σ
m



]


T






(
26
)








Finally, the third term of equation (19) can be expanded by applying a simplifying assumption based on the relative geometry of the backbones in remote actuated continuum system configurations. The stiffness of the continuum robot, as measured from the actuation forces at the proximal end of the actuation lines, is a function of strain throughout the length of the actuation lines. As illustrated in FIG. 7, the contributions to the axial stiffness are divided into the stiffnesses, kb and kc, corresponding to the bending, Lb, and non-bending, Lc, regions of the actuation lines connecting the working distal end to the actuation unit.


The axial stiffness along the length of a given actuation line can then be expressed as










1
k

=


1

k
c


+

1

k
b







(
27
)








where







k
c

=



EyA

L
c







and






k
b


=

EyA

L
b








and A denotes the cross-sectional area of the backbone.


For continuum robotic systems with remote actuation that are designed to access deep confined spaces, the lengths of the non-bending regions of the actuation lines far exceed that of the bending regions, Lc>>Lb. The stiffness will therefore be dominated by the non-bending regions of the actuation lines. Local perturbations of the backbones at the actuation unit can be expressed as













T



q


=

K
q







Where




(
28
)








K
q



[






E
Y


A


L
c




0


0




0





0




0


0





E
Y


A


L
c





]





mxm





(
29
)








Expanding terms by applying the chain rule and using the instantaneous inverse kinematics of equation (3),








T



ψ






is given by












T



ψ


=





T



q






q



ψ






K
q



J

q





ψ








(
30
)








The configuration space stiffness therefore reduces to











[

K
ψ

]

ij

=



[

H
ψ

]

ij

-



[






ψ
j





(

J

q





ψ


[
i
]


)


]

T


T

-



[

J

q





ψ


[
i
]


]

T



K
q



J

q





ψ


[
J
]








(
31
)







Using the generalized force and stiffness as defined in equations (15) and (31), a compliant motion controller can be constructed to minimize the difference between the expected and measured actuation forces in the secondary backbones. The controller provides compliant motion control of each continuum segment subject to a perturbing wrench at the end disk of the segment. This wrench approximates a multitude of small perturbation forces acting along the length of a continuum segment during an insertion through a tortuous path (e.g., a cavity of unknown size, shape, and dimensions). In an analogy to a linear spring model with an equilibrium position, f=k(xeq−x), there exists an equilibrium pose, {b(k)Peqb(k)Req}, at which the wrench is minimized in the operation space of the continuum segment. Given this equilibrium position and the projection of the applied wrench to the configuration space, there exists a unique, though unknown, configuration ψ(k),d=g(b(k)Peq, b(k)Req) that minimizes the wrench applied to the continuum segment. The objective of the compliance controller is to advance to this position using the available sensing information of the actuation forces in the backbones, T(k) and therefore minimize the interaction wrench.


For multi-segment continuum robots, a pose exists in the overall configuration space that minimizes the augmented generalized force on the system. The augmented generalized force vector for an n-segment continuum robot

fa=[f(1)T . . . f(n)T]T  (32)

is associated with the augmented configuration space

ψa=[ψ(1)T . . . ψ(n)T]T  (33)


The configuration space stiffness of an individual segment is generalized as the following to result in the augmented configuration space stiffness of the multi-segment continuum robot










K

ψ
a


=

[




K

ψ
,

(
1
)





0





0




0



K

ψ
,

(
2
)


























0




0





0



K

ψ
,

(
n
)






]





(
34
)







An error function is defined as the distance in configuration space from the current configuration, ψa to the desired configuration ψad, as

eψaad−ψa  (35)

For a passive wrench condition, the equilibrium pose and corresponding configuration space remain fixed, e.g., ψad=0. For external wrenches changing slowly with respect to the compliant control update rate, this condition becomes ψad≈0 and hence negligible when taking the time derivative of eψn. The following discussion uses ψad=0 although it is to be understood that the same derivation follows for ψad≈0 by changing the equality sign to an approximation sign.


The time derivative of the error function under these conditions becomes

eψa=−{dot over (ψ)}a.  (36)


For small perturbations, the distance in configuration space is given as Δψaad. Thus by applying the configuration space stiffness Kψa, the error in the system can be related to the generalized force as

fa=Kψaeψa.  (37)

Where Δfa≅fa for the small perturbations. This assumption holds for robots that are calibrated such that fa≈0 for unloaded movements throughout the workspace.


During control of a continuum system the estimated generalized force {circumflex over (f)}a is calculated using the idealized statics model of fa based on the estimate of the energy and measured actuation forced as in equation (16). This estimate is contaminated by an error λ due to un-modeled friction and strain along the actuation lines, perturbations from circulate-bending shape of individual segments, deviations in the cross-section of the backbones during bending, and uncertainties in the elastic properties of the NiTi backbones. Thus without compensation, the generalized force estimate takes the form

{circumflex over (f)}a,uncompensated=fa+λ  (38)

where fa is given by equation (16).


The generalized force error is identified using the definition in equation (38) for movements of the continuum robot through its workspace with no externally applied wrenches. During this unloaded movement, the wrench at the end disk is we=0 and equation (15) predicts fa=0. In an ideal continuum robot lacking backlash, friction and other un-modeled effects, the prediction of the generalized force based on the measured values of the actuation forces T(k) in equation (16) for each segment would also return fa=0. However, the actual kinetostatic effects cause fa=0 and this deviation forms λ that we seek to estimate. In order to compensate for the errors due to the interaction between segments, non-linear regression via Support Vector (SV) machines is investigated and applied.


These model errors are highly dependent on the pose of the robot and the path in the configuration space to this pose. To compensate for the error, a feed forward term is added to equation (38) to reduce the effects of λ during compliant motion control such that the compensated generalized force estimate is given by

{circumflex over (f)}a=fa+λ−{circumflex over (λ)}.  (39)

An augmented compliant motion controller, taking into account the estimates of the un-modeled error, {circumflex over (λ)}, takes the form

{dot over (ψ)}a=μA{circumflex over (f)}a  (40)

where μ and A correspond respectively to positive definite scalar and matrix gains to be chosen by the operator.


A compliant motion controller utilizing the error compensation techniques described above, results in a system error that is uniformly bounded for any generalized force error by

eψa∥>∥Kωa−1(λ−{circumflex over (λ)})∥.  (41)


The dynamics of the error in the configuration space applying equation (40) to equation (36) and accounting for equation (39) is represented as

ėψa=μA(Kψaeψa+λ−{circumflex over (λ)})  (42)


A Lyapunov function candidate of the error system for compliant control, represented by equation (42), can be defined as










v


(

e

ψ
a


)


=


1
2



e

ψ
a

T



Pe

ψ
a







(
43
)








where P is any symmetric positive definite matrix. Differentiating equation (43) with respect to time and accounting for equation (42) yields

{dot over (V)}(eψaTψaT=−μeψaTPA(Kψaeψa+λ−{circumflex over (λ)})  (44)

Choosing the control and Lyapunov weighting matrices as A=Kψn−1 and P=I, the derivative of the Lyapunov function reduces to)

{dot over (V)}(eψa)=−μ(eψaTeψa+eψaTKψa−1(λ−{circumflex over (λ)}))  (45)

A controller implementing these techniques relies on the invertibility of the configuration space stiffness. The block diagonal matrix is constructed of the sub-matrices, Kψ(k) as in equation (34). Singular configurations of Kψ(k) and, therefore, Kψa correspond with a straight segment,







θ


(
k
)

=

π
2



.





For control purposes, the effect of singular poses can be mitigated using a singularity robust inverse of the configuration space stiffness.


Noting the expression eψaTeψa is positive definite for all eψa and μ>0 it is sufficient to show ∥eψaTeψa∥>∥eψaTKψa−1(λ−{circumflex over (λ)})∥ to prove the time derivative of the Lyapunov function candidate is negative definite.


Assuming the bound on the generalized force error, represented by equation (41), and applying the identity ∥eψaT∥∥eua∥=∥eψaTeψa∥ yields

eψaTeψa∥>∥eψaT∥∥Kψa−1(λ−{umlaut over (λ)})∥  (46)

Applying the Schwarz inequality ∥eψaT∥∥Kψa−1(λ−{umlaut over (λ)})∥≧∥eψT Kψ−1 (λ−{circumflex over (λ)})∥ to equation (46), the condition on the generalized force error assumed for stability can be expanded as

eψaTeψa∥>∥eψaTKψa−1(λ−{circumflex over (λ)})∥  (47)

thus proving the stability of the controller given the bounds on the compensation error.


The techniques described above illustrate controller stability for estimation uncertainties, λ−{circumflex over (λ)} that are small with respect to the system error, eψa. In order to maintain a stable pose in configurations where ∥eψaTeψa∥≈∥(λ−{circumflex over (λ)})∥, i.e. at configurations close to the minimum of the generalized force, the input to the controller is filtered such that estimation error does not drive accidental motion. In the example controller described in further detail below, a dead-band filter is used to ensure that the controller acts for deviation above a reasonable bound for the estimation error. The performance compromise of applying this filter is a reduction in the sensitivity of the controller.


Bounds for the sensitivity of the compliant motion controller, defined by equation (40), are limited by the error in canceling the generalized force uncertainties, λ−{circumflex over (λ)} For small load perturbations to the continuum robot, the errors in the generalized force, λ, are well approximated by a function of the robot pose in configuration space ψa and the trajectory leading to this pose. ψa Furthermore, the trajectory required to achieve a pose influences the friction and backlash in the system at the current pose. The performance of the controller depends on canceling deviations from the idealized model. As specified in equation (39), this cancellation is carried out by a feed-forward term, {circumflex over (λ)} that is obtained though off-line training and online estimation of the model error via support vector regression (SVR).


SV machines provide a method for nonlinear regression through mapping of the input vectors into a higher dimensional feature space. Parameters for the estimation are learned by application of empirical risk minimization in this feature space through convex optimization. A subset of the training data forms the support vectors which define the parameters for regression. The robustness and favorable generalization properties with noisy data, coupled with a compact structure which allows real-time function estimation during motion control motivate the choice of a SV machine.


To estimate the error in the generalized force based on an initial unloaded exploration of the workspace, the “ν” SV Regression (ν-SVR) is employed along each dimension of the generalized force. The ν-SVR algorithm provides a means for controlling the sparsity of support vectors, therefore providing robustness to over-fitting while simultaneously reducing the number of control parameters required to be defined.


The training set for the ν-SVR contains input pairs {x[l], y[l]}t=1N based on the pose and generalized force gathered during an exploration of the continuum robot workspace in the absence of external perturbing forces. For the ith component of the generalized force, the input is given as











x

[
I
]


=



[



ψ

a
,
1




N
max



(

ψ

a
,
1


)



,





,


ψ

a
,

2

n





N
max



(

ψ

a
,

2

n



)



,



ψ
.


a
,
1




N
max



(


ψ
.


a
,
1


)



,





,



ψ
.


a
,

2

n





N
max



(


ψ
.


a
,

2

n



)




]

T



R

4

n















y

[
I
]


=



f

a
,
i




w
e


=
0






(
48
)








where N is the number of training samples,







max
N



(

ψ

a
,
i


)






is the maximum recorded magnitude of the ith row of ψa over the set 1ε[1,N], and ψa is the configuration space velocity. This expression normalizes each element of the input vector x[l] to the range of [−1, 1] for all data in the training set.


Given these training input vector pairs, ν-SVR provides a method for estimating the function

f(x)=custom characterw,φ(x)custom character+b  (49)

where (·,·) is the inner product space, w and b are parameters to be determined by the convex optimization and φ(·)R4th→Rnxh is a mapping of the input feature vector x[l] to a higher dimensional feature space.


As specified in equation (49), the SVR algorithm allows mapping of the input space to a higher dimensional vector space. Uncertainties in predicting the generalized force, including friction and non-linear bending, are modeled by exponential functions. As such, a Gaussian radial basis function (RBF) kernel

k(x[l],x[m])=e−γ∥(x[l]x[m])∥2,  (50)

is chosen as a suitable candidate for higher dimensional mapping.


The resulting ν-SVR model for function estimation with a new input vector, x*, is given by










f


(
x
)


=




SV











(


a
i
*

-

a
i


)



k


(


x

[
i
]


,

x
*


)




+
b





(
51
)








It should be noted that only those training points x[l], y[l], denoted SV in equation (51), for which |y[l]−f(x[l])|≧ε form the support vectors. During the computation of new estimates, only these support vectors contribute to the final function estimation of equation (51), thus enforcing sparsity in the regression.


Software, such as LibSVM, provided by C. C. Chang and C. J. Lin at http://www.csie.ntu.edu.tw/cjlin/libswm, is employed for solving for the optimal parameters of equation (51) for each coordinate of the generalized force independently. The measured error in the generalized force λ and the output of the regression for each component of the error compensation, equation (51), is presented for a sample data set in FIG. 8. An inset detailing λ1 at higher resolution is provided in FIG. 9. Data for this sample set, including the robot pose, trajectory and actuation forces, was collected at 125 Hz during an unloaded motion in the configuration space of a two-segment continuum robot. The trajectories in each configuration space variable, θ(1), δ(1), θ(2), δ(2), are uncorrelated to provide a robust data set for estimation. Frames displayed in the FIGS. 8 and 9 are given for every tenth collected sample. The ν-SVR was trained with the first half of the data set, labeled as “Training” in the figure. The regression function was then applied without further training on the remainder of the samples, labeled “Estimate”. The compensation error given by the difference between the predicted {circumflex over (λ)} and actual λ is presented for each direction of the generalized force.


The ν-SVR displays good generalization to the untrained data. The compensation provides a minimum of 1.4 times reduction in the RMS error for λ4 and a maximum of 2.5 times reduction for λ1. While the ν-SVR reduces errors on average, the compensation is locally imperfect as can be seen by maxima in the error in the λ directions exceeding the measured errors, FIG. 8. The magnitude of the predicted ν-SVR values exceed the measured values, e.g. FIG. 9 for λ1, producing local increases in the compensated predicted force given by {circumflex over (f)}λ in equation (39). Filtering is applied to smooth outliers in the prediction values.



FIG. 10 illustrates an example of a real-time controller for the compliant motion algorithm. This multi-rate controller can be implemented utilizing the Matlab xPC computing environment. The main control loop updating the control values at the joint level runs at 1 kHz. Joint forces are measured at 5 kHz and smoothed with a moving average filter and down-sampled to the 1 kHz control loop. The support vector regression (SVR) is run at 100 Hz. A moving average filter smoothes outliers in the estimate provided by the support vector regression functions of equation (51).


Joint force sensors 701 provide actuation force measurements for individual segments of the continuum robot, T(m). The actuation forces are utilized to determine a Jacobian matrix linearly mapping the configuration space velocities to joint velocities (step 703). The Jacobian matrix 703 is multiplied by the energy gradient 705 at step 707. The estimated augmented generalized force errors 709 are filtered by a low pass filter 711. At step 713, the filtered force error is multiplied by the combination of the Jacobian matrix 703 and the energy gradient 705 to provide an estimated augmented force, Fa. In order to reduce aberrant motions of the controller due to modeling and estimation errors, a dead-band filter 715 is applied to the estimated generalized force to reduce joint motion due to uncompensated errors.


The inverse of the configuration space stiffness 717 is applied to determine difference, Δψa, in the configuration space between the current configuration of the continuum robot and the desired configuration. The controller then determines the configuration space vector for an equilibrium pose of the continuum robot (step 719). The Jacobian matrix mapping configuration space velocities to joint velocities is applied to the determined equilibrium pose of the continuum robot (step 721) to determine joint positions, ·q, for the equilibrium pose. An integral 723 is applied and the output provided to a Joint PID controller 725 that adjusts the position of the continuum robot segments to conform to the detected forces.


In the examples described above, the compliant motion controller uses a feed forward term for compensation of model uncertainties. The sum of the uncertainty estimate and the expected generalized force are filtered through a dead-band to prevent motion by the controller due to errors in the compensation. Thus, generalized forces less than the threshold of the deadband filter will be neglected and the threshold for this filter therefore forms a tradeoff between the sensitivity to external perturbations and insensitivity to errors in the model and compensation.


In order to quantify the effects of the controller and thresholding, the sensitivity of the controller to external wrenches was quantified on a single-segment continuum robot. FIG. 11 illustrates an experimental system that is used to evaluated the sensitivity of the continuum robot. A wrench was applied at the end disk of the segment 1101 by a Kevlar thread 1105, attached through a pulley system 1106 to calibrated weights 1107. The load direction at each pose was quantified relative to the base of the robot by an optical tracking system 1109 with a specified accuracy of 0.20 mm RMS. Optical markers 1104 mounted to the Kevlar thread 1105 and to the base of the continuum robot 1103 serve to specify the direction of the applied force. The weight of the thread and markers is less than 1 gram and is therefore negligible with respect to the loads required to initiate the compliant motion.


The optical tracking system 1109 provides a specification for the linear accuracy of the device while the experiment requires an orientation prediction. The linear accuracy can be used to estimate the orientation accuracy of the optical tracking system 1109 by noting the orientation of a vector that is calculated based on the position of two marker points. The smallest linear distance between marker points of 48.5 mm used for the orientation estimation occurs at the base marker system 1103. Although the direction marker perpendicular to the thread is significantly shorter, this direction is not used for computing the direction vector of the Kevlar thread 1105. An RMS error of 0.2 mm at a moment of 24.25 mm corresponds to an orientation error of less than 0.5°.


For the sensitivity measurement at each pose, the segment was guided into position by manually applying an external wrench and allowing the continuum structure to comply to the sampled configuration. The pose estimate was measured via the nominal kinematics and was verified by an embedded magnetic tracker system 1108 with an RMS orientation accuracy of 0.5°. The load direction was measured via the optical trackers after a 10 gram weight was applied to the Kevlar thread to straighten the thread length between the optical markers. Calibration weights were added to the load in 1 gram increments until the threshold for motion was exceeded. The dead-band of the controller was set during the sensitivity experiments as

f1∥≦20 Nmm, ∥f2∥≦10 Nmm.  (52)

These thresholds were determined empirically based on the error compensation in the generalized force and the stability of the controller.


Sensitivity measurements were recorded for 28 poses shown for the odd samples in FIG. 12. The experimental data is presented in FIGS. 13 and 14. Poses were selected throughout the workspace to ensure a distribution with load directions varying relative to the pose angle δ. The mean pose error and standard deviation of the nominal kinematics from the measured pose of the magnetic sensors is given in FIG. 15. Note at poses in which θ=˜90°, the accuracy of δ as reported by the magnetic tracking system 1108 reduces significantly due to a configuration singularity in the magnetic tracking system 1108. Poses 7 and 20, corresponding to configurations θ=90° and θ=84°, respectively, were therefore excluded from the error calculation for δ1. The accuracy verifies the nominal kinematics of the single segment and these values were used for the subsequent analysis. The mean perturbation force required to induce motion under the experimental conditions was 0.99 N with a standard deviation of 0.28 N. The maximal force required to induce motion was 1.5 N.


The sensitivity measurements provide an opportunity to evaluate the contribution of the model uncertainties and the compensation by ν-SVR. Under ideal conditions in which the generalized force is undisturbed by uncertainty, equation (15), the applied force required to induced motion can be estimated as the minimum force required to exceed the motion threshold defined by equation (52). The minimum force required to exceed the threshold in the direction of the applied force measured for each pose based on the idealized model is provided in addition to the measured force in FIG. 14. The average difference between the measured and ideal force was 0.37 N with a standard deviation of 0.14 N. Thus, the data show that model uncertainty contributes significantly to the sensitivity of the controller.


Noting the experimental setup is sized appropriately for use in exploration and intervention during minimally invasive sinus surgery, the compliant controller for this robot demonstrated adequate sensitivity for this application. Average interaction forces for functional endoscopic sinus surgery have been measured at 2.21 N and forces required to breach the sinus walls ranged between 6.06 N and 17.08 N. The compliant motion controller demonstrated in these experiments obtains a comfortable margin of safety for exploration and interaction.


To evaluate the controller in the setting of an application, a two segment continuum robot was inserted into an acrylic tube with a three-dimensional shape comprised of multiple out of plane bends. The tube was mounted to an insertion stage that autonomously brought the tube into contact with the robot in a manner analogous to blind insertion into a cavity and subsequent retraction. The controller had no prior knowledge of the geometry of the tube or the path plan of the insertion stage. As illustrated in FIG. 16, the controller successfully complied with the confined complex shape despite a moving contact location unknown to the controller.


The generalized force estimates during insertion and retraction are presented in FIG. 17. The data display the effect of the threshold on the motion of the system when subject to external perturbations. Generalized force magnitudes below the threshold for motion, denoted by the dashed lines in FIG. 17, are filtered and do not cause motion of the continuum robot. As the generalized force exceeds the threshold, the controller rapidly moves to reduce the force to a level below the threshold. It should be noted that the controller is agnostic to the location of contact and does not therefore require location information for minimization of the environment contact. The results demonstrate the utility of the algorithm for compliant motion control at unknown locations along the length of a continuum robot.


Trans-Nasal Throat Surgery


Minimally Invasive Surgery of the throat is predominantly performed trans-orally. Although trans-oral (TO) access provides a scarless access into the airways, its outcomes are affected by complications, high cost, and long setup time. Continuum robotic systems such as described herein can be used to provide trans-nasal (TN) access to the throat. Furthermore, as described below, a hybrid position/compliant motion control of a rapidly deployable endonasal telerobotic system can also be used to safely manipulate the robot during trans-nasal access. The system uses a unique 5 mm surgical slave with force sensing capabilities used to enable semiautomation of the insertion process. Working channels in the continuum robot allow the deployment of surgical tools such as a fiberscope, positioning sensors, grippers, suction tubes, cautery, and laser fibers. The treatment of vocal fold paralysis is chosen as a benchmark application and a feasibility study for collagen injection is conducted. Experiments on a realistic human intubation trainer demonstrated successful and safe TN deployment of the end effector and the feasibility of robotic-assisted treatment of vocal nerve paralysis.



FIGS. 18A, 18B, and 18C illustrate an example of a robotic system for trans-nasal (TN) access to the throat. A nasopharyngeal tube 1801 is inserted into the nasal cavity 1803 through the nose. The continuum robot is extended through the pharynx 1805 to reach a surgical site at the larynx 1807. As shown in FIG. 18B, the robotic stem 1809 is inserted into the nasopharyngeal tube 1801 and the continuum robot 1811 extends from the distal end of the nasopharyngeal tube 1801 at the surgical site. In this example—as illustrated in FIG. 18C, the distal end of the continuum robot 1811 includes a needle 1813 for performing vocal fold repair at the surgical site and a fiberscope 1815. A bronchoscope 1817 is also inserted with the robot through the nasal cavity 1803. The end-effector of the continuum robot 1811 is composed of both active and passive multi-backbone continuum segments. A hybrid motion/compliance controller assists the surgeon during the insertion phase by actively complying to the unknown environment while allowing the operator to control the insertion depth and speed.


The robotic system of FIG. 18A is operated using a dexterous 5 DoF continuum manipulator, a Sensable Phantom Omni, an Ascension 3D Guidance trakSTAR 2 with flat metal immune transmitter, a 4 mm bronchoscope, and a 1.2 mm fiberscope. FIG. 19 illustrates an example of an actuation unit that drives the movement of the continuum robot on seven controlled axes, of which six control the two continuum segments and one controls the insertion depth into the nasopharyngeal tube. The actuation unit includes a robotic stem 1901, a linear slider 1903 (which controls the extension of the continuum robot from the robotic stem 1901), one or more load cells 1905 (for monitoring actuation forces), and one or more potentiometers 1907 (for redundant positioning information).


The system can operate in both passive and semi-active modes. The passive mode is based on a standard telemanipulation architecture where the operator guides the end-effector via a master manipulator (the Phantom Omni) while observing endoscopic images provided by the in-hand fiberscope. The semi-active mode is used to reach the surgical site. During the semi-active mode the surgeon commands the insertion depth while the continuum manipulator autonomously complies with the anatomy using a variation of the compliance motion controller described above.



FIG. 20 illustrates a surgical slave portion of the robotic system that is composed of a flexible passive stem and two active segments. Each 5 mm segment is composed of four super-elastic NiTi backbones (one central and three secondary ones) that provide two DoF for bending in any direction. An additional DoF is provided by the linear stage of the actuator (described in FIG. 19 above), which controls the insertion of the base of continuum arm. The robotic arm has three 1.8 min lumens that allow for the deployment of surgical instruments. In order to compensate for the unknown shape of the passive segment constrained by the nasopharyngeal tube, a 0.9 mm 6 DoF electro-magnetic sensor is attached to the base of the two-segment continuum robot. The metal immune flat transmitter makes the system robust to surrounding metal and easy to place under the patient's head.



FIG. 20 illustrates five coordinate systems that are defined to describe the direct kinematics of the surgical slave: the world frame Bw defined by vectors {^xw, ^yw, ^zw}, the frame attached to the exit of the nasopharyngeal tube B0 defined by vectors {^x0, ^y0, ^z0}, the base frame of the actively bending continuum robot B1 defined by vectors {^x1, ^y1, ^z1}, the base frame of the second segment B2 defined by vectors {^x2, ^y2, ^z2}, and the end effector frame B3 defined by vectors {^x3, ^y3, ^z3}.


The position and orientation of end-effector frame B3 in B0 may be described by the following augmented configuration space vector:

Ψ=[θ1δ1qinsθ2δ2θ3δ3]T  (53)

where, qins is the insertion depth and angles θk and δk are defined similarly for the passive segment (k=1) and active segments (k=2, 3) as depicted in FIG. 20. Using Ψ, the position and orientation of frame B3 in B0 is given by:










p
3



0

=


p
1



0

+


R
1



0



(


p
2



1

+


R
2



1



p
3



2



)







(
54
)








R
3



0

=


R
1



0



R
2



1



R
3



2








where




(
55
)







p
k




k
-
1


=



L
k


Θ
k




[




cos






(

δ
k

)



(


sin






θ
k


-
1

)








-
sin







(

δ
k

)







(


sin






θ
k


-
1

)








-
cos







θ
k





]






(
56
)







R
k




k
-
1


=

Rot






(


-

δ
k


,

z
^


)


Rot






(


-

Θ
k


,

y
^


)






Rot






(


δ
k

,

z
^


)






(
57
)








with: L1=qins, L2, and L3 being the lengths of the first and second active segments. θkk−π/2, and operator Rot(a,b) being the rotation matrix about axis b by angle a. Note that, since the first segment is passive, θ1 and δ1 are not directly controllable. In the remainder of this example, we assume that θ1 and δ1 and the origin of from B1 are measured by a magnetic tracker (the position and the orientation frame B1 is known). Hence, the forward kinematics is calculated using θ1 and δ1 and B1 along with joing values qi, i=1 . . . 6.


The configuration space vector Ψ relates to the joint space vector as

q(Ψ)=[qinsq2(Ψ)Tq3(Ψ)T]T  (58)

where q2 and q3 are the amount of pushing-pulling on the secondary backbones of active segments 2 and 3. In particular










q
2

=

r


[






Θ
1






cos






(

δ
2

)


-


Θ
0






cos






(

δ
0

)










Θ
1






cos






(


δ
2

+
β

)


-


Θ
0






cos






(


δ
0

+
β

)










Θ
1






cos






(


δ
2

+

2

β


)


-


Θ
0






cos






(


δ
0

+

2

β


)






]






(
59
)







q
3

=

r







Θ
2



[




cos






(

δ
2

)







cos






(


δ
2

+
β

)







cos






(


δ
2

+

2

β


)





]







(
60
)







θ
0

=


π


/


2

-

atan





2


(





R
13
2

+

R
23
2


,




R
33


)







(
61
)







δ
0

=


-
atan






2


(


R
23

,

R
13


)






(
62
)








where β=2π/3, r is the radial distance of the secondary backbone from the center of the base disk, Θ00−π/2, Θ11−π/2, and Rij is element ij of rotation matrix wR1 obtained from the magnetic sensor placed at the based of the first active segment. Note that angles θ0 and δ0 allow us to work in local frame B0 decoupling the kinematics of the distal active and passive segments from shape variations of the passive stem.



FIG. 21 illustrates the control architecture of the telesurgical system. Control inputs and electro-magnetic orientation information are both received at 125 Hz over the Local Area Network while encoder and actuation force signals are sampled at 1 kHz and 5 kHz respectively. The conventional hybrid motion/compliance control is adopted in which two separate controllers independently provide motion and compliance control commands. However, the hybrid motion/compliance control approach is adapted to our continuum robot by decomposing the control task in configuration space rather than in task space. The projection matrices Ω and Ω ensure that the control commands are projected into subspaces for motion and compliance control. Joint-level commands to the actuators are then obtained through the inverse position of the continuum manipulator and the required model-based actuation compensation. The following details describe the specific implementation of our approach.


(1) Compliant Motion Control:


Compliance Motion Control (CMC), as described above, allows multi-backbone continuum robots with intrinsic actuation sensing to autonomously steer away from constraints without a priori knowledge of the contact nor the external wrench. In the following, the CMC control mechanism is modified in order to use only information about actuation forces sensed on the most distal segment. This control law allows the robot to actively comply to the circle-shaped nasopharyngeal tube. If actuation force information on the second active segment is available, the actuation force error is defined as:

τe33τ3  (63)

where τ3 are the expected actuation forces and τ3 are the sensed actuation forces acting on the third segment respectively. We now project the actuation force error, τe3, into the configuration space of the distal segment obtaining the generalized force error:

fe3=JTτe3  (64)

where Jis the Jacobian matrix that relates the configuration space velocities to the joint space velocities.


Hence, the desired configuration space velocity vector that steers the robot away from the unknown contact is:

{dot over (Ψ)}e=ΦKψ2−1fe3  (65)

where Kψ2 is the configuration space stiffness matrix of the second segment and









Φ
=


[



0


1


0


1


0




0


0


1


0


1



]

T





(
66
)








Note that Equation (65) is a simplification of the algorithm presented above for compliant motion control for multiple segments. In the case of TN insertion, assuming an overall circular shape of the entire manipulator, both segments need to bend by the same angle in order pass through the nasopharyngeal tube.


(2) Motion Control:


Telemanipulation of the surgical slave is achieved by defining a mapping between the movement of the master's end-effector and the desired motion directions in the fiberscope image space as shown in FIGS. 22A, 22B, and 22C. Because of the difficulties in accurately controlling the two active segments and the long unknown-shaped passive stem, the movement of the Phantom Omni manipulator control (shown in FIG. 22B) is mapped only to 3 DoF of the most distal segment in this example: 1 DoF of insertion and 2 DoF of bending (as in a conventional bronchoscope). Therefore, once the robot is inserted (shown in FIG. 22A), the first segment is bent (θ1=60) in the direction of the vocal folds (δ1=0). The user advances the robot in the direction of ^zf (insertion) and tilts about axes ^xf and ^yf in fiberscope-attached frame. The fiberscope-attached frame (shown in FIG. 22C) is related to B3 by a known fixed rotation. This movement in image space is first mapped to the movement of the master stylus {^xms, ^yms, ^zms} and then to the movement of the distal segment frame {^x3, ^y3, ^z3}.


The desired position and orientation of distal segment are given as follows:

2p3,des=2p3,curr+2R3,currpdes,master  (67)
2R3,des=2R3,currRTRdes,masterR  (68)

where matrix R defines the transformation between the camera-attached frame (FIG. 22C) and the master's stylus (FIG. 22B). Once the desired pose is computed, the desired twist tdes is computed and the desired configuration space velocities are obtained as follows:










[





q
.

ins







θ
.

2







δ
.

2




]

=



(

ΓΣ






J
2


)


-
1



ΓΣ







t
des

.






(
69
)








In Equation (69), J2 is the Jacobian matrix of the distal segment:










J
2

=

[



0




L
2



c

δ
2







Θ
2



c

θ
2



-

s

θ
2


+
1


Θ
2
2






-



L
2




s

δ
2




(


s

θ
2


-
1

)




Θ
2







0




-

L
2




s

δ
2







Θ
2



c

θ
2



-

s

θ
2


+
1


Θ
2
2






-



L
2




c

δ
2




(


s

θ
2


-
1

)




Θ
2







1




L
2






Θ
2



s

θ
2



+

c

θ
2




Θ
2
2





0




0



-

s

δ
2







c

δ
2




c

θ
2







0



-

c

δ
2







-

s

δ
2





c

θ
2







0


0




-
1

+

s

θ
2






]





(
70
)








matrix Σ transforms the desired twist into gripper frame









Σ
=

[




R

3
,
curr

T


2



0




0



R

3
,
curr

T


2




]





(
71
)








And selection matrix Γ defines a desired subtask









Γ
=


[



0


0


1


0


0


0




0


0


0


1


0


0




0


0


0


0


1


0



]

.





(
72
)








In this example, matrix Γ selects the third, fourth, and fifth rows of the Jacobian matrix allowing to control only 3 DoF: translation along z3 and tilting about x3, y3. As a result, we only invert a square 3×3 matrix and control only the desired DoFs.


Finally, the augmented desired configuration space velocity vector is given as follows:

{dot over (Ψ)}m=[{dot over (q)}ins 0 0 {dot over (θ)}2 {dot over (δ)}2]T  (73)


(3) Projection Matrices:


Depending on the operational mode (insertion or telemanipulation) the configuration space Ψ can be partitioned in directions in which motion needs to be controlled, T, and directions in which compliance needs to be controlled, C. Similar to wrench and twist systems in the hybrid motion/force control formulation, these two spaces, T and C, are orthogonal and their sum returns the configuration space Ψ(T+C=Ψ). It is, therefore, possible to construct two projection matrices, Ω and Ω, that project desired configuration space velocities into the motion space T and into the compliance space C:

Ω=T(TTT)TT  (74)
Ω=I−Ω  (75)

where T is a 5×m matrix in which its columns define a base of T and superscript indicate the pseudo-inverse. For example, in the case of compliant insertion, configuration variables qins, δ2, and δ3 will be position-controlled while variables θ2 and θ3 will be compliance-controlled allowing the segment to adapt to the shape of the nasal conduit. Hence, matrix T is defined as:









T
=


[



1


0


0


0


0




0


0


1


0


0




0


0


0


0


1



]

T





(
76
)







(4) Actuation Compensation:


The desired joint variables are computed using a theoretical kinematics model and a model-based actuation compensation.


Motion Force Control of Multi-Backbone Continuum Robots


This section presents a general framework for hybrid motion/force control of continuum robots. The examples described below assume that the kinematic model is known and that the robot is equipped with a device for measuring or estimating environmental interaction forces. This information can be provided by a dedicated miniature multi-axis force sensor placed at the tip of the robot or by an intrinsic wrench estimator of the types. A multi-backbone continuum robot with intrinsic wrench estimation capabilities is used to demonstrate the hybrid motion/force control framework. The following assumptions specifically apply to multi-backbone continuum robots with intrinsic force sensing. Different assumptions are necessary for different types of robots but the fundamental control framework remain invariant.


Assumption 1: The continuum robot bends in a circular shape and gravitational forces are negligible.


Assumption 2: The continuum robot is able to sense actuation forces via load cells placed between each actuation line and its actuator.


Assumption 3: The geometric constraint is known and the environment is rigid. This information is used for both the hybrid motion/force controller and the intrinsic wrench estimation. However, because of the innate compliance of continuum robots and as demonstrated by experimental results, an exact knowledge of the geometric constraint is not necessary.



FIG. 23 shows an example of a hybrid motion/force controller for rigid-link robot manipulators. Motion and force controllers provide two separate control signals that are first projected into allowable motion and force directions (using projection matrices Ω and Ω) and then merged into the joint-space of the manipulator. Motion commands are first transformed into task-space wrenches using the inverse of the inertia matrix B and then into joint-torque commands using the transpose of the Jacobian matrix J. The desired joint-torque vector Γ is then added to the feedback linearization term that compensates for non-linearities (e.g. coriolis/centrifugal and gravitational effects) and fed to the joint-space PID controller.



FIG. 24 shows a hybrid motion/force controller for multi-backbone continuum robots with intrinsic force sensing. As in the example of FIG. 23, two separate controllers produce motion and force commands that are then projected into allowable motion/force directions using projection matrices Ω and Ω. Hence, the motion and force commands are projected into the configuration space velocity of the continuum manipulator using respectively the inverse of the Jacobian matrix J and a composition of the transpose of the matrix J and the configuration space compliance matrix K−1. The configuration space compliance matrix provides a mapping between the change in task-space wrenches and the change in configuration space velocities. Finally, using the closed-form inverse position of the manipulator, the theoretical desired joint-space positions qdes are obtained. Similar to the feedback linearization term in the example of FIG. 23, an additional term is obtained through the statics of the continuum manipulator and the stiffness of the actuation lines. This term include both an actuation compensation term for the applied wrench at the tip of the robot and a compensation term for extension and friction in the actuation lines.


Control Architecture—A First-Order Model of Contact:


Hybrid motion/force control aims at controlling the interaction of two rigid bodies by decoupling control inputs into allowable relative motions and constraining wrenches. The control inputs are specifically generated to maintain contact between the two bodies by simultaneously generating motion directions that do not break the contact state and apply the desired interaction wrench. For example, in the case of frictionless point contact (as illustrated in FIGS. 25A and 25B), body 1 can translate along axes x and y, rotate about axes ^x, ŷ, and {circumflex over (z)}, and apply a force along axis {circumflex over (z)}, i.e. the normal vector between body 1 and body 2.


Regardless of the type of contact, it is possible to define two dual vector sub-spaces, one containing wrenches F6, and the other containing motion screws M6. The reciprocal product between these two spaces is defined as the rate of work done by a wrench fi acting on a motion screw mj. In the case of rigid bodies, under conservative contact, the bases of the two spaces must satisfy the reciprocity condition. At any given time, the type of contact between the two rigid bodies defines two vector sub-spaces: a n-dimensional space of normal vectors NF6 and a (6−n)-dimensional space of tangent vectors TM6, where n is the degree of motion constraint. The bases of these two spaces can be defined by a 6×n matrix N and a 6×(6−n) matrix T. The columns of N and T are respectively any n linearly independent wrench in N and any 6−n linearly independent motion screw in T. As a consequence of the reciprocity condition and the contact constraint, the scalar product of any column of N with any column of T is zero, i.e.

NTT=0  (77)


For example, for the contact constraint depicted in FIGS. 25A and 25B, matrices N and T are given by:










N
=

[



1


0


0


0


0




0


1


0


0


0




0


0


0


0


0




0


0


1


0


0




0


0


0


1


0




0


0


0


0


1



]


,





T
=

[



0




0




1




0




0




0



]






(
78
)








Although in many situations matrices N and T are simply the composition of canonical vectors in IR6 and can be obtained by inspection, this is not the case when dealing with complex interaction tasks and multi-point contacts.


The efficacy of hybrid motion/force control stems from its ability to produce adequate motion and force control inputs that do not violate the reciprocity condition (Equation 77). The reciprocity of the control inputs is enforced by projecting each control input into the correct subspace by pre-multiplication of a projection matrix. We, therefore, define two projection matrices Ωf and Ωm that project any control input into consistent wrenches and twists respectively:

Ωf=N(NTN)−1NT
Ωm=T(TTT)−1TT=I−Ωf.  (79)


According to the classical formulation of hybrid motion/force control, the frame-work inputs are defined by the desired twist tref=[vrefTωrefT]T and the desired interaction wrench at the operational point qref=[frefTmrefT]T.


At any given time, the wrench error is given by:

we=wref−wcurr  (80)

where wcurr is the sensed wrench.


The output of the motion controller, tdes, is first projected onto the allowed motion space M6 via projection matrix Ωm as defined in equation (79) and then onto the configuration space velocity of the manipulator via the pseudo-inverse of the Jacobian matrix J:

{dot over (Ψ)}m=JΩmtdes  (81)

One the other hand, the output of the motion controller wdes can be obtained with a conventional PI control schemes:

wdes=Kf,pwe+Kf,i/we,  (82)


Similarly to the motion controller, the desired wrench wdes is first projected into the allowed wrench space F6 via projection matrix Ωf as defined in equation (79), then into the generalized force space via the transpose of the Jacobian matrix J. The generalized force is the projection of the task-space wrench acting at the end effector into the configuration space of the manipulator. Finally into the configuration velocity space of the continuum manipulator via the configuration space compliance matrix Kψ−1:

{dot over (Ψ)}f=Kψ−1JTΩfwdes.  (83)


Using equations (81) and (83) the motion and force control inputs are merged into a configuration space velocity vector Ψ{dot over ( )} that does not violate the contact constraint:

{dot over (Ψ)}={dot over (Ψ)}m+{dot over (Ψ)}f.  (84)


Equation (84) provides the desired configuration of the continuum manipulator that accomplishes both the desired motion and force tasks without violating the contact constraint. The next step in the control architecture is to generate joint-level commands to accomplish the desired tasks. Because of the flexibility of the arm, actuation compensation is required for both achieving the desired pose and applying the desired wrench at the end-effector. Using the statics model, the desired actuation forces τdes are obtained as follows:

τdes=(JT)(∇U−JTΩfwref)  (85)


According to a model-based actuation compensation scheme, the desired joint-space compensation is given by:

ε=Ka−1τdes  (86)

where Ka−1 designates the compliance matrix of the actuation lines.


By combining equations (84) and (86), the desired joint-space control input is obtained as follows:

qdes={circumflex over (q)}des(Ψ)+ε  (87)

where ^qdes(Ψ) is the joint's positions associated with configuration (Ψ) according to the theoretical inverse position analysis.


The hybrid motion/force control architecture for continuum robots with intrinsic force sensing is summarized in FIG. 24. Two independent controllers provide high-level control commands for both motion and force regulation. These commands are projected into adequate force-vectors and velocity-vectors that do not violate the contact constraint and then they are projected into the configuration space of the continuum manipulator. The motion commands are projected using the inverse of the Jacobian matrix J, while the force commands are projected using first the transpose of the Jacobian matrix J and then the configuration space compliance matrix Kψ−1. The configuration space stiffness matrix describes how a change in the external wrench direction and magnitude is related to a change in the configuration of the continuum manipulator. Once the desired configuration space vector is obtained, a model-based actuation compensation scheme is used to produce the required joint-space displacements for both configuration compensation and the acting wrench. Note that, equation (85) includes two terms: the first compensate for actuation line extension, friction, and model uncertainties, while the second term is a feedforward term that produces the desired wrench at the end-effector by actuation the manipulator in joint-space. Finally, the control input qdes is fed into the low-level PID controller. In the case of continuum robots with intrinsic wrench estimation, there are two additional components: the friction compensation/estimation block, and the wrench estimator.


Compensation Uncertainties:


During control of the real continuum robot there will be a deviation λ between the desired actuation force vector τdes and the sensed actuation force vector tcurr. This deviation is due to friction and extension in the actuation lines, perturbation of the bending shape from the ideal circular configuration, and geometric and static parameters. Thus, the sensed actuation force vectors is as follows:

τcurrdes+λ.  (88)


Force deviation λ is a function of the configurations Ψ of the manipulator and the joint-space velocities Several methods have been proposed in order to characterize friction and uncertainties. A discrete Dahl model for friction compensation in a master console may be implemented. A Dahl friction model can also be implemented into the control architecture of steerable catheters. Friction estimation and compensation can also be used in the control of concentric tube robots. A non-linear regression via Support Vector regressors might also be used to compensate for lumped uncertainties in multi-backbone multi-segment continuum robots.


Wrench Estimation:


Continuum robots with actuation force sensing allow to estimate external wrenches acting at the tip. Using a statics model, the external wrench acting at the tip of the continuum robot is given by:












w
curr

=




(

J

t





ψ

T

)





(



U

-


J

q





ψ

T



(


τ
curr

-
λ

)



)


+


(

I
-



(

J

t





ψ

T

)





J

t





ψ

T



)


η








where






η
=


D




F
T




S
e



(


w
se

-



(

J

t





ψ

T

)





(



U

-


J

q





ψ

T



(


τ
curr

-
λ

)



)



)









D
=



(

I
-



(

J

t





ψ

T

)





J

t





ψ

T



)

T




S
e



(

I
-



(

J

t





ψ

T

)





J

t





ψ

T



)










F
=

(

I
-



(

J

t





ψ

T

)





J

t





ψ

T



)









S
e

=

[





(



n
^

t

×


n
^

n


)




(



n
^

t

×


n
^

n


)

T





0

3
×
3







0

3
×
3





I

3
×
3





]









W
se

=


[






c
t




n
^

t


+


n
t




n
^

n








0

3
×
1





]

.






(
89
)








Se and Wse contain a priori knowledge of the contact constraint and guide the estimation algorithm. The a priori knowledge is defined by contact normal vector {circumflex over (n)}t, and contact tangential vector ^nt. These two vectors define the plane in which the sensible component of the external wrench lies.


Experimental Results:


In order to validate the proposed framework, the control algorithms were implemented on the one-segment multi-backbone continuum robot of FIGS. 26A and 26B. The continuum segment is able to translate along the {circumflex over (z)}0 axis providing the end-effector with a total of 3 DoFs: qins and angles θ and δ. The continuum segment is equipped with three load cells that monitor the forces acting on the three secondary backbones. Estimation of the ^x and ŷ component of a force acting at the tip of the manipulator is possible. In the remainder of this section, multiple experiments are presented to validate the efficacy and usefulness of the proposed framework. While the motion controller always controls motion in z direction, the force controller switches between regulating a force in the ^x or ŷ directions depending on the task.


The remainder of this section is organized as follows. First, the experimental setup is presented. The continuum robot manipulator and required equipment are described. Second, the estimation of uncertainties such as friction and un-modeled actuation forces are presented. Finally, three experiments are presented: force regulation in the ^x and ŷ direction, shape estimation, and stiffness characterization.


The Continuum Manipulator—Direct Kinematics:


The surgical slave of FIGS. 26A and 26B is the composition of a linear stage and a two Degree of Freedom (DoF) continuum manipulator. The continuum segment has three push-pull backbones that allows for bending its end disk in space. For the ease of presentation, in the remainder of this section, the kinematics and statics of the manipulator is summarized. Six coordinate systems are defined (Figure V.4): 1) world frame {^x0, ^y0, ^z0}, 2) segment's base disk frame {^x1, ^y1, ^z1}, 3) segment's bending plane frame {^x2, ^y2, ^z2}, 4) segment's end-disk frame {^x3, ^y3, ^z3}, 5) segment's gripper frame {^x4, ^y4, ^z4}, and 6) segment's tool frame {^x5, ^y5, ^z5}. The position, p0, and the orientation, R03, of the tool in reference frame is given by:

p50=p10+R10p31+R40p54
R50=R40=Rot(−δ,{circumflex over (z)})Rot(θ,{circumflex over (y)})Rot(δ,{circumflex over (z)})  (90)

where R10=I, p10=[0 0 qins]T, p32=[0 0 d]T, d is the distance between frames {4} and {5} (see FIGS. 26A and 26B), p31 is the position of the end disk of the continuum segment as in II.2, Θ=θ−θ0, L is the nominal length of the continuum segment, θ0=π/2, and operator Rot(ø, ŵ) returns a rotation of angle ø about axis ŵ. The pose of the tool is uniquely defined by configuration variables θ, δ, and qins. We, therefore, define the configuration space vector ΨεIR3 as:

Ψ=[θδqins]T  (91)


In order to achieve configuration Ψ, the secondary backbones of the continuum robot (i=1, 2, 3) are shortened or lengthened as follows:

qi=τ cos(δi)(θ−θ0)  (92)

where δi=δ+(i−1)β, β=⅔π, and r is the radial distance of each secondary back-bone from the centrally-located backbone. Similarly to the configuration space, we define the augmented joint-space vector qξIR4 as:

q=[q1q2q3qins]T.  (93)


Differential Kinematics:


The tool twist tT=[vTωjT] is given by:

t=J{dot over (Ψ)}  (94)

where Ψ{dot over ( )} is the rate of change of the configuration space vector Ψ and











J

t





ψ


=

[






-

dc
Θ




c
δ


-



Lc
δ



c
θ


Θ

-


A
2


Θ
2








-

ds
Θ




s
δ


+


A
1

Θ




0







dc
Θ



s
δ


+



Ls
δ



c
θ


Θ

+


A
1


Θ
2








-

ds
Θ




c
δ


+


A
2

Θ




0






ds
Θ

+


Lc
θ


Θ
2


-


Ls
θ

Θ




0


1





-

s
δ






c
δ



c
θ




0





-

c
δ






-

s
δ




c
θ




0




0




-
1

+

s
θ




0



]


,




(
95
)








where cy=cos(y), sy=sin(y), A1=L sin (δ)(sin(θ)−1), and A2=L cos(δ)(sin(θ)−1). Similarly, the configuration space velocities are related to the configuration space velocities as:











q
.

=


J

q





Ψ




Ψ
.








where







J

q





Ψ


=


[




r






cos


(

δ
1

)







-
r







Θsin


(

δ
1

)





0





r






cos


(

δ
2

)







-
r







Θsin


(

δ
2

)





0





r






cos


(

δ
3

)







-
r







Θsin


(

δ
3

)





0




0


0


1



]

.






(
96
)







Statics:


Using virtual work arguments we can derived the following first order linear relationship:














J
~


t





Ψ

T



w
e


+



J
~


q





Ψ

T


τ


=


U







where









J
~


t





Ψ


=


J

t





Ψ




[



1


0




0


1




0


0



]



,







J
~


q





Ψ


=


J

q





Ψ




[



1


0




0


1




0


0



]



,




and









U

=


E
Y




I


[





Θ
L

+




i
=
1

3



Θ

L
+

q
i




-



Θ
2

2


r





i
=
1

3




cos


(

δ
i

)




(

L
+

q
i


)

2












Θ
3

2


r





i
=
1

3




sin


(

δ
i

)




(

L
+

q
i


)

2







]


.







(
97
)







Configuration Space Stiffness:


The configuration space stiffness is used for compliant motion control. Let the wrench acting on the end disk that is projected into the configuration space of the kth segment be given as the generalized force vector

f(k)=J(k)Twe,(k).  (98)

Applying equation (97) to the generalized force expression, the ith row of the generalized force f(k) can be written as

ft=∇Ui−[JT]iτ=∇Ui−[J[i]]Tτ.  (99)

where J[i] denotes the ith column of Jqψ.


For small perturbations from an equilibrium configuration, the stiffness of the individual continuum segment can be posed in the configuration space as

δf=Kψδψ  (100)

where the stiffness is given by the Jacobian of the generalized force with respect to configuration space perturbation. Thus, the elements of Kψ are given by:
















f
i





ψ
j



=




[

K
ψ

]

ij







=














ψ
j





[




U
i


-



[

J

q





ψ


[
i
]


]

T


τ


]


.








(
101
)







The elements of the stiffness matrix (equation (101)) can be expanded as











[

K
ψ

]

ij

=



[

H
ψ

]

ij

-



[











ψ
j





(

J

q





ψ


[
i
]


)


]

T


τ

-



[

J

q





ψ


[
i
]


]

T






τ




ψ
j



.







(
102
)








The first term of the configuration space stiffness, Hψ, is the Hessian of the elastic energy of the segment given by










H
ψ

=


[







2


U




θ
2









2


U




θ




δ











2


U




δ




θ









2


U




δ
2






]

.





(
103
)








The axial stiffness along the length of a given actuation line can then be expressed as










1
k

=


1

k
c


+

1

k
b







(
104
)








where







k
c

=



E
Y


A


L
c







and







k
b

=



E
Y


A


L
b



,





and A denotes the cross-sectional area of the backbone.


For continuum robotic systems with remote actuation designed to access deep confined spaces, the lengths of the non-bending regions of the actuation lines far exceed that of the bending regions, Lc>>Lb. The stiffness will therefore be dominated by the non-bending regions of the actuation lines. Local perturbations of the backbones at the actuation unit can be expressed as













τ



q


=

K
α







where




(
105
)








K
q



[






E
Y


A


L
c




0


0




0





0




0


0





E
Y


A


L
c





]





m
×
m






(
106
)







Expanding terms by applying the chain rule and using the instantaneous inverse ∂τ kinematics, ∂ψ is given by















τ



ψ


=






τ



q






q



ψ














K
α



J

q





ψ










(
107
)







The configuration space stiffness therefore reduces to











[

K
ψ

]

ij

=



[

H
ψ

]

ij

-



[











ψ
j





(

J

q





ψ


[
i
]


)


]

T


τ

-



[

J

q





ψ


[
i
]


]

T



K
α



J

q





ψ


[
j
]








(
108
)







Kinematic and Static Parameters:


The numerical value of the kinematic and static parameters defined in the previous sections are reported in the table of FIG. 27. r is the radial distance from the secondary backbone to the central backbone, L is the nominal length of the continuum segment, β is the division angle between secondary backbones, EY is the Young's modulus of the NiTi backbones, od is the outer diameter of the backbones, and









I
=


π
64



o
d
4






(
109
)








is the second area moment of each backbone.


Estimation Uncertainties:


Uncertainties are due to: 1) deviation of the kinematic and static parameters from the nominal ones reported in the table of FIG. 27, 2) unmodeled friction along the actuation lines, 3) statics and kinematics modeling assumptions, and 4) actuation unit assembly. The robot used in this work is a 0 5 mm continuum robot with a cone that re-route the actuation lines and an actuation line length of more than 300 mm. In this work, we calibrate actuation uncertainties by populating a look-up table that depends on the configuration of the continuum manipulator.


Methods:


The continuum manipulator of FIGS. 26A and 26B is commanded to scan its workspace between δ=π/2 and δ=−π/2 with intervals of 5°˜=0.098 rad. At each δ configuration the manipulator is bent from θ=π/2 to θ=0 with constant velocity and accomplishment time of 10 s. The discrepancy between the expected actuation forces and the sensed actuation forces was recorded.


Results: FIGS. 28, 29, and 30 show the actuation force errors on backbone one, two, and three respectively. The graphs show a plot of the actuation force error versus the bending angle θ for different values of δ.



FIG. 28 shows the actuation force error, τe1, associated with the first backbone. The graphs shows how the actuation force error depends on both θ and δ and, therefore, on the configuration of the manipulator. The error on backbone one reaches its minimum at δ=π/2 and δ=−π/2. In these two configurations backbone one is neither extended nor shortened and the load on it is, therefore, zero. In all other configurations, the error mainly increases as a function of γ but also as a function of δ.



FIG. 29 shows the actuation force error, τe2, associated with the second back-bone. In this case, the minimum is reached for δ=−π/6. In this configuration the second backbone is neither extended nor shortened and, therefore, the resultant load is zero. In all other configurations, τe2, is non-zero and mainly depends on the bending angle θ. In this case, it is possible to see the effect of friction along the line. For configurations with a negative δ, backbone two is extended while for configurations with positive δ, backbone two is shortened. This phenomenon is not seen in backbone one because between δε[−π/2, π/2] the backbone is only shortened.



FIG. 29 shows the actuation force error, τe3, associated with the third backbone. Similarly to backbone n°2, because of symmetry, the actuation force error τe is zero at δ=π/6, negative for δε(π/6, π/2], and positive for δε[−π/2, π/6).


Several methods can be used to characterize friction and uncertainties. In this work, we populated a lookup table using the data shown in FIGS. 28, 29, and 30. The table has a size of 36×18 and linearly interpolates over 6 and 0 with increments of 5°. In the current implementation, the table is only populated with data associated with negative θ{dot over ( )}, i.e. the continuum segment bends from θ=π/2 (straight configuration) to θ=0. For this reason, the compensation is not effective when the motion is reversed; thus affecting the force estimation. Although it is possible to produce velocity-dependent lookup tables, this is excluded from the scope of this work.


Force Regulation:


This section presents force regulation experimental results. The goal of these experiments is to demonstrate the ability of the controller to regulate a predetermined force in both x and y directions at different configurations. As illustrated in FIG. 31, the experimental setup consists of a 5 mm continuum robot, an interaction probe with a spherical tip of 0 5 mm radius, an aluminum block, and an ATI Nano 17 for ground truth.


Methods:


In order to test the force estimation and force controller efficacy in the x^ direction the continuum robot is bent to the following three configurations: 1) θ=80°, δ=0°, 2) θ=60°, δ=0°, and 3) 1) θ=40°, θ=0°. At each configuration, a reference force magnitude of 5 gr, 10 gr, and 15 gr were commanded. Data from the force estimator and the ATI Nano 17 were compared and the rise time and steady state error computed.


In order to test the force estimation and force controller efficacy in the y^ direction the continuum robot is bent to the following configurations: 1) θ=80°, δ=0°, 2) θ=60°, δ=0°, and 3) 1) θ=40°, δ=0°. At each configuration, a reference force magnitude of 10 gr is tested. Data from the force estimator and the ATI Nano 17 are compared and the rise time and steady state error are computed.


Results:



FIGS. 34A, 34B, and 34C; FIGS. 35A, 35B, and 35C; and FIGS. 36A, 36B, and 36C show the step response for force magnitudes 5 gr, 10 gr, and 15 gr in the x^ direction at θ=80°, θ=60°, and θ=40° respectively. Each graph shows the time history of three quantities: desired force (black), sensed force by the ATI Nano 17 (red), and sensed force by the intrinsic force estimator (blue). These results are summarized in the table of FIG. 32.



FIGS. 37A, 37B, and 37C show the step response for a force magnitude of 10 Gr in y^ direction at θ=80°, θ=60°, and θ=40°. The results are summarized in the table of FIG. 33.


The experimental results demonstrate both that the hybrid motion/force control is able to regulate forces of different magnitudes in different directions and that the accuracy depends on the configuration of the manipulator. Steady state error in the x direction between the force sensed by the ATI Nano 17 and the intrinsic force estimator are mainly due to residual un-modeled uncertainties as the more energy is stored into the system (θ=π/2 zero energy, θ=0 maximum energy). These uncertainties are static and dynamic friction, bending shape, and extension/contraction of the actuation lines. Steady state error in the y direction is due to uncompensated uncertainties for side motions δ./=0 and the much more compliance of the continuum manipulator in the δ direction at this particular configuration.


As shown in FIGS. 28, 29, and 30, uncertainties are symmetric depending on the configuration of the backbones. The efficacy of the intrinsic force estimator and, therefore, the force controller is definitely weaker in the δ direction. However, depending on such configuration, the x and y directions are consecutively affected in different ways. It is worth noting that the experiments were conducted on a non-calibrated robot in which geometric parameters (nominal length, distance between backbones, bending shape) and static parameters (Young's modulus, actuation line stiffness, and second moment area of all backbones) were set to the nominal value. Furthermore, the intrinsic force estimator could also undergo proper calibration as in any force/torque sensor. However, this is beyond the scope of this work in which we aim to demonstrate force control schemes for continuum robots and their use in several scenarios.


Force Regulated Shape Estimation:


This section presents environment's shape estimation experimental results. The goal of these experiments is to demonstrate simultaneous force and motion control. The user is able to control the end-effector while free of contact and engage the force control in pre-determined directions when in contact with the environment. FIGS. 38A and 38B illustrate the experimental setup which consists of a 5 mm continuum robot, a diamond-shape silicon phantom, an Ascension Technologies trakSTAR 2 with flat transmitter placed under the silicone phantom, and a Force Dimension Omega 7.


The experimental setup of FIGS. 38A and 38B performs shape estimation of a silicon diamond-shaped extrusion (shown in FIG. 38A). The base plane of the extrusion is placed at approximately 18 mm from the origin along the x direction (shown in FIG. 38B). The user actively controlled motion of the probe in the y and z directions. The force controller regulates a force with a magnitude of 0.1 N in the x direction.


Methods:


The 5 mm continuum robot is equipped with a plastic probe having a 5 mm radius sphere at the interaction point. The sphere reduces the impingement of the probe into the soft tissue. A 0.9 mm magnetic coil is delivered through one of the robot's working channels and secured to the probe. A silicon diamond-shaped extrusion is placed in a YZ plane at a distance of approximately 18 mm from the robot's reference frame as shown in FIGS. 38A (top view) and 38B (side view).


The end-effector's motions in the y^ and z^ directions were commanded via a Force Dimension Omega 7 with 3-axis force feedback. Position commands were sent over the Local Area Network (LAN) using User Datagram Protocol (UDP) at 100 Hz. The end-effector's position was acquired at 125 Hz using the Ascension Technology trakSTAR 2 and sent over the LAN using UDP at 100 Hz. The high-level motion and force controllers and the wrench estimator run at 200 Hz while the low-level joint controller run at 1 kHz. Switching between full motion control and hybrid motion/force control was enabled using the 7th axis of the Omega 7 (gripper).


The continuum robot, under full motion telemanipulation mode, is guided to reach a point on the silicon phantom. Once hybrid motion/force control is enabled, the continuum robot autonomously regulates a force of −0.1 N in the x^ direction. Position data of the probe were only collected when the sensed force in the x^ direction was smaller or equal to −0.05 N and the hybrid motion/force controller was engaged. These conditions ensured that each data point was actually on the surface of the silicon phantom. Switching between full motion/force control and hybrid motion/force control allowed to cover a workspace of 18 mm×30 mm×40 mm.


Ground truth shape data was obtained using a second probe equipped with another 0 0.9 mm magnetic coil as shown in FIG. 39. The probe was manually swept over the silicon phantom and data collected. The use of an identical probe equipped with a similar sensor ensures comparison of data having the same accuracy, repeatability, noise, and uncertainties.


Position data from the electro-magnetic tracker were stored and linearly interpolated using Matlab function grid data. This function interpolates the surface at query points on the YZ plane and returns the interpolated value along the x^ direction. Multiple data points are automatically averaged during the interpolation.


Results:


The estimated shape using the continuum robot is shown in FIG. 40 while the ground truth data obtained with the manual scan is shown in FIG. 41. The error between the estimate shape and the ground truth shape is presented in FIG. 42. As expected, the maximum deviation is found at the boundaries of the robot's workspace along the y^ axis. In fact, in order for the continuum segment to stretch along the y^ axis the bending angle θ decreases considerably and the δ angle decreases (positive y^) or increases (negative y^). As shown in the force regulation experiments reported in the previous section, the sensitivity of the force estimation in the x^ direction decreases considerably while the sensitivity in the y^ direction increases. Although the controller is unable to regulate the requested amount of force due to the force estimator, the continuum manipulator does not lose contact with the surface. This phenomenon is not seen at the boundaries of the workspace along the z^ direction because the insertion stage provides most of the displacement.


The very small inertia of the continuum manipulator allows the force controller to maintain contact with the unknown surface without perfect knowledge of the tangent and normal vectors at the contact point. These experiments demonstrate the efficacy of the proposed hybrid motion/force control scheme to perform independent motion and force regulation. The intrinsic compliance of the continuum manipulator also makes the impact phase stable allowing for safe and smooth transitions between full motion control and hybrid motion/force control.


Stiffness Imaging:


This section presents experimental results on stiffness characterization of soft tissues using the proposed hybrid motion/force controller. The goal of the experiment is to build a stiffness image of the surrounding environment using both position and force data. One way to build such image is to repetitively scan the surface applying different force and recording the displacement of each point between scans. FIG. 43 illustrates the experimental setup which includes a 5 mm continuum robot, a plastic probe with a spherical tip of 5 mm radius, a 0.9 mm electro-magnetic sensor, and a silicone phantom with embedded rubber tubes.


Methods:


Five consecutive surface scans were completed under hybrid motion/force control applying respectively 5 gr, 10 gr, 15 gr, 20 gr, and 25 gr. After selecting the desired force magnitude, the operator guides the robot to cover the designated area (as shown in FIG. 43). A rubber tube is embedded at approximately 155 pixels (px) from the base of the robot. Using the ruler shown in FIG. 43, it is possible to define a scaling factor between image pixels and mm. In this case, 39 px=10 mm. Using this scaling ratio, the position of the rubber tube is identified at approximately 39.7 mm from the base of the manipulator. The operator was asked to scan a rectangular area of approximately 20×30 mm.


Position data during each scan were recorded from the electro-magnetic sensor placed at the tip along with the sensed force in the x^ direction and smoothed by spline interpolation. Because of the position RMS of the Ascension Technologies trakSTAR 2 it was chosen to use the first and the last scan in order to obtain a better noise/signal ratio.


Results:


The estimated surfaces under 5 Gr force control and 25 Gr force control are shown in FIGS. 44 and 45. FIG. 44 shows a color map of the estimated surface with points between 10 mm and 13 mm along the x direction. FIG. 45 shows a color map of the estimated surface with points between 12 mm and 15 mm along the x direction.


In order to characterize the difference in stiffness along the surface (not the absolute stiffness) a linear spring-model is used. FIG. 46 shows the estimated stiffness values across the scanned area. The graph shows a peak of 0.3 N/mm at approximately 40 mm from the base of the robot. The estimated stiffness decreases to 0.25 N/mm, 0.2 N/mm, and 0.15 N/mm respectively along both positive z direction and negative z direction. Lower stiffness is estimated at the boundaries of the scanned surface (z=55 and z=25). FIG. 43 shows that the rubber tube lays along the y axis at approximately 155 px=39.7 mm from the base of the robot. The stiffness map clearly identifies high stiffness along that same axis as shown in FIG. 46.


Thus, the invention provides, among other things, systems and methods for controlling the pose of a multi-segmented continuum robot structure to adapt to the unknown dimensions of a cavity. The shape and position of the individual segments of the continuum robot are continually adjusted as the continuum robot is advanced further into the cavity, thereby providing for compliant insertion of a continuum robot into an unknown cavity. Various features and advantages of the invention are set forth in the following claims.

Claims
  • 1. A method of controlling movement of a continuum robot, the continuum robot including a plurality of independently controlled segments along a length of the continuum robot, the method comprising the acts of: inserting the continuum robot into a cavity of unknown dimensions or shape;determining a plurality of forces acting on the plurality of segments along the length of the continuum robot by the surrounding cavity, wherein determining the plurality of forces acting on the plurality of segments along the length of the continuum robot includes determining a plurality of forces including a generalized force acting on each of the plurality of segments along the length of the continuum robot, each force of the plurality of forces including a magnitude and a direction;comparing each generalized force of the plurality of forces to a respective expected generalized force for each of the plurality of segments, the expected generalized force being based on the position of the continuum robot;receiving a positioning command from a manipulator control, the positioning command indicating a desired movement for a distal end of the continuum robot;augmenting the desired movement for the distal end of the continuum robot based, at least in part, on the determined plurality of forces acting on the plurality of segments along the length of the continuum robot to restrict movement of the continuum robot within safe boundaries of the surrounding cavity,wherein augmenting the desired movement for the distal end of the continuum robot includes adjusting the position of each segment of the plurality of segments based on a difference between the determined generalized force and the expected generalized force for each of the plurality of segments; andadjusting the position of the continuum robot based on the augmented desired movement.
  • 2. The method of claim 1, wherein the cavity is a nasal passage of a patient and further comprising advancing the continuum robot into the nasal cavity until the distal end of the continuum robot reaches a surgical site in the throat of the patient, wherein the act of advancing the continuum robot includes advancing the position of the continuum robot based on the positioning command from the manipulator control, and where the act of augmenting the desired movement of the continuum robot includes determining an updated positioning for each segment along the length of the continuum robot based on the determined plurality of forces acting on the continuum robot by the surrounding cavity.
  • 3. The method of claim 1, wherein augmenting the desired movement for the distal end of the continuum robot includes determining a set of allowable motions for the continuum robot;determining a set of allowable forces for the continuum robot;projecting the set of allowable motions and the set of allowable forces as projection matrices into a joint space corresponding to a manipulator control;translating motion commands from the manipulator control into one or more task specific wrenches using an inverse of an inertia matrix; andtranslating the one or more task specific wrenches into a joint-torque vector command using a Jacobian matrix,wherein adjusting the position of the continuum robot based on the augmented desired movement includes adjusting the positioning of the continuum robot based on the joint-torque vector command using a joint-space PID controller.
  • 4. The method of claim 1, further comprising: advancing the continuum robot further into the cavity; andrepeating the acts of determining the plurality of forces acting on the plurality of segments, comparing each generalized force of the plurality of forces to a respective expected generalized force for each of the plurality of segments, and adjusting the position of each segment of the plurality of segments as the continuum robot is further advanced into the cavity.
  • 5. The method of claim 1, further comprising: determining the position of the continuum robot; anddetermining the expected generalized force for each of the plurality of segments based on previously stored data corresponding to the position of the continuum robot.
  • 6. The method of claim 1, wherein adjusting the position of the continuum robot based on the augmented desired movement includes adjusting the position of each segment of the plurality of segments to minimize the difference between the determined force and the expected generalized force for each of the plurality of segments.
  • 7. The method of claim 1, further comprising, after advancing the distal end of the continuum robot to a target location, bracing the continuum robot against surfaces of the cavity by adjusting the position of each segment of the plurality of segments to increase a difference between the determined generalized force and the expected generalized force for each of the plurality of segments until the difference reaches a threshold.
  • 8. The method of claim 1, wherein adjusting the position of the continuum robot includes operating each of a plurality of actuators to advance or retract one of the plurality of back-bone structures relative to the continuum robot, the plurality of back-bone structures each extending through the length of the continuum robot and being coupled to at least one of the plurality of segments.
  • 9. The method of claim 8, wherein determining a plurality of forces acting on the plurality of segments along the length of the continuum robot by the surrounding cavity includes measuring a force exerted on one of the plurality of back-bone structures by one of the plurality of actuators.
  • 10. The method of claim 9, wherein measuring the force exerted on one of the plurality of back-bone structures includes determining a force required to hold the continuum robot in a current position while counteracting external forces acting on the plurality of segments by the surrounding cavity.
  • 11. The method of claim 1, wherein receiving the positioning command from the manipulator control includes receiving a command to advance the continuum robot further into the cavity.
  • 12. The method of claim 11, further comprising repeating the acts of determining the plurality of forces acting on the plurality of segments, augmenting the desired movement for the distal end of the continuum robot, and adjusting the position of the continuum robot as the continuum robot is advanced into the cavity.
  • 13. A control system for a continuum robot, the control system being configured to control the movement of the continuum robot being inserted into a cavity of unknown dimensions or shape, the control system comprising: the manipulator control;a compliant insertion controller configured to determine a plurality of forces acting on a plurality of segments along a length of the continuum robot by the surrounding cavity by determining a plurality of forces including a generalized force acting on each of the plurality of segments along the length of the continuum robot, each force of the plurality of forces including a magnitude and a direction, andcompare each generalized force of the plurality of forces to a respective expected generalized force for each of the plurality of segments, the expected generalized force being based on the position of the continuum robot; anda motion controller configured to receive a positioning command from the manipulator control, the positioning command indicating the desired movement for the distal end of the continuum robot,augment the desired movement for the distal end of the continuum robot based, at least in part, on the determined plurality of forces acting on the plurality of segments along the length of the continuum robot to restrict movement of the continuum robot within safe boundaries of the surrounding cavity,wherein augmenting the desired movement for the distal end of the continuum robot includes adjusting the position of each segment of the plurality of segments based on a difference between the determined generalized force and the expected generalized force for each of the plurality of segments, andadjust the position of the continuum robot based on the augmented desired movement.
RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/819,808, filed on May 6, 2013 and titled “METHOD AND SYSTEM FOR COMPLIANT INSERTION OF CONTINUUM ROBOTS,” the entire contents of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant IIS-1063750 awarded by the National Science Foundation. The government has certain rights in the invention.

US Referenced Citations (156)
Number Name Date Kind
2988237 Devol Jun 1961 A
3580099 Mosher May 1971 A
4744264 Milenkovic May 1988 A
4795296 Jau Jan 1989 A
4802461 Cho Feb 1989 A
5046375 Salisbury, Jr. Sep 1991 A
5231989 Middleman Aug 1993 A
5337732 Grundfest et al. Aug 1994 A
5345937 Middleman et al. Sep 1994 A
5386741 Rennex Feb 1995 A
5397323 Taylor Mar 1995 A
5410638 Colgate Apr 1995 A
5480406 Nolan Jan 1996 A
5662587 Grundfest et al. Sep 1997 A
5749828 Solomon et al. May 1998 A
6113593 Tu Sep 2000 A
6197017 Brock Mar 2001 B1
6309346 Farhadi Oct 2001 B1
6554844 Lee Apr 2003 B2
6669711 Noda Dec 2003 B1
6676684 Morley Jan 2004 B1
6692485 Brock Feb 2004 B1
6817974 Cooper et al. Nov 2004 B2
6837892 Shoham Jan 2005 B2
6843793 Brock Jan 2005 B2
6858005 Ohline Feb 2005 B2
6860878 Brock Mar 2005 B2
6949106 Brock Sep 2005 B2
7021173 Stoianovici Apr 2006 B2
7099745 Ebert Aug 2006 B2
7214230 Brock May 2007 B2
7235089 McGuckin, Jr. Jun 2007 B1
7316681 Madhani Jan 2008 B2
7391173 Schena Jun 2008 B2
7682319 Martin et al. Mar 2010 B2
7699835 Lee Apr 2010 B2
7787681 Zhang et al. Aug 2010 B2
7822249 Garty et al. Oct 2010 B2
7837615 Le et al. Nov 2010 B2
7854738 Lee Dec 2010 B2
7887549 Wenderow Feb 2011 B2
7959557 Weitzner et al. Jun 2011 B2
8025635 Eaton Sep 2011 B2
8088101 Chang Jan 2012 B2
8114062 Muni Feb 2012 B2
8116886 Simaan et al. Feb 2012 B2
8172828 Chang May 2012 B2
8303576 Brock Nov 2012 B2
8311626 Hlavka Nov 2012 B2
8337521 Cooper Dec 2012 B2
8343141 Madhani et al. Jan 2013 B2
8365633 Simaan et al. Feb 2013 B2
8372019 Goldenberg Feb 2013 B2
8377077 Reis Feb 2013 B2
8409234 Stahler Apr 2013 B2
8414505 Weitzner Apr 2013 B1
8414598 Brock Apr 2013 B2
8444549 Viola May 2013 B2
8460236 Roelle Jun 2013 B2
8480618 Wenderow et al. Jul 2013 B2
8486053 Niemeyer Jul 2013 B2
8498691 Moll Jul 2013 B2
8504201 Moll Aug 2013 B2
8545551 Loulmet Oct 2013 B2
8551115 Steger Oct 2013 B2
8585731 Abbate Nov 2013 B2
8864757 Klimovitch et al. Oct 2014 B2
20020120252 Brock Aug 2002 A1
20030120305 Jud Jun 2003 A1
20040116906 Lipow Jun 2004 A1
20040176751 Weitzner Sep 2004 A1
20050043718 Madhani Feb 2005 A1
20050054900 Mawn et al. Mar 2005 A1
20050059960 Simaan et al. Mar 2005 A1
20050228440 Brock Oct 2005 A1
20060036182 Daniels et al. Feb 2006 A1
20060047302 Ortiz Mar 2006 A1
20060058861 Gibson et al. Mar 2006 A1
20060156851 Jacobsen Jul 2006 A1
20060241414 Nowlin Oct 2006 A1
20060258938 Hoffman Nov 2006 A1
20070197939 Wallace Aug 2007 A1
20070225787 Simaan et al. Sep 2007 A1
20080033240 Hoffman Feb 2008 A1
20080065108 Diolaiti Mar 2008 A1
20080071288 Larkin et al. Mar 2008 A1
20080114492 Miegel et al. May 2008 A1
20080179301 Garty et al. Jul 2008 A1
20080181473 Garty et al. Jul 2008 A1
20080188800 Bencini Aug 2008 A1
20080243063 Camarillo Oct 2008 A1
20080243064 Stahler Oct 2008 A1
20080243106 Coe Oct 2008 A1
20080245173 Schwerin Oct 2008 A1
20080249536 Stahler et al. Oct 2008 A1
20080262513 Stahler et al. Oct 2008 A1
20080302200 Tobey Dec 2008 A1
20090054222 Zhang et al. Feb 2009 A1
20090076476 Barbagli et al. Mar 2009 A1
20090076521 Hansen Mar 2009 A1
20090088774 Swarup et al. Apr 2009 A1
20090171151 Choset et al. Jul 2009 A1
20090216083 Durant Aug 2009 A1
20090275818 Rau et al. Nov 2009 A1
20090275857 Cabiri et al. Nov 2009 A1
20100010504 Simaan et al. Jan 2010 A1
20100011900 Burbank Jan 2010 A1
20100030377 Unsworth Feb 2010 A1
20100069719 Wehrheim Mar 2010 A1
20100076269 Makower Mar 2010 A1
20100079308 Fabre Apr 2010 A1
20100099951 Laby et al. Apr 2010 A1
20100125165 Torii May 2010 A1
20100152899 Chang et al. Jun 2010 A1
20100256558 Olson Oct 2010 A1
20100331858 Simaan et al. Dec 2010 A1
20110015649 Anvari et al. Jan 2011 A1
20110066160 Simaan et al. Mar 2011 A1
20110071541 Prisco Mar 2011 A1
20110071544 Steger Mar 2011 A1
20110125165 Simaan May 2011 A1
20110184241 Zubiagte et al. Jul 2011 A1
20110196419 Cooper Aug 2011 A1
20110213346 Morley et al. Sep 2011 A1
20110230894 Simaan Sep 2011 A1
20110306929 Levesque et al. Dec 2011 A1
20110313243 Zubiate Dec 2011 A1
20110319910 Roelle et al. Dec 2011 A1
20120071822 Romo Mar 2012 A1
20120109274 Simaan et al. May 2012 A1
20120123395 Stoy May 2012 A1
20120241576 Yu Sep 2012 A1
20120253131 Malkowski Oct 2012 A1
20120289946 Steger Nov 2012 A1
20130012928 Cooper et al. Jan 2013 A1
20130023859 Malkowski Jan 2013 A1
20130090763 Simaan Apr 2013 A1
20130096540 Cooper et al. Apr 2013 A1
20130110131 Madhani et al. May 2013 A1
20130131868 Rucker May 2013 A1
20130165869 Blumenkranz Jun 2013 A1
20130165945 Roelle Jun 2013 A9
20130178838 Malkowski Jul 2013 A1
20130190741 Moll Jul 2013 A1
20130197539 Simaan et al. Aug 2013 A1
20130218141 Hinman Aug 2013 A1
20130231529 John Sep 2013 A1
20130269109 Yu Oct 2013 A1
20130274715 Chan Oct 2013 A1
20130289581 Yeung Oct 2013 A1
20130300537 Bajo et al. Nov 2013 A1
20130303945 Blumenkranz Nov 2013 A1
20130306112 Blumenkranz Nov 2013 A1
20130338433 Goldman et al. Dec 2013 A1
20140058406 Tsekos Feb 2014 A1
20150073434 Simaan et al. Mar 2015 A1
Foreign Referenced Citations (18)
Number Date Country
2335558 Jun 2011 EP
2005009482 Feb 2005 WO
2005112834 Dec 2005 WO
2008036304 Mar 2008 WO
WO 2009094670 Jul 2009 WO
2009097461 Aug 2009 WO
2009097539 Aug 2009 WO
2009124287 Oct 2009 WO
2009140688 Nov 2009 WO
2010042611 Apr 2010 WO
2011063511 Jun 2011 WO
2012015816 Feb 2012 WO
2012049623 Apr 2012 WO
2013043804 Mar 2013 WO
2013158974 Oct 2013 WO
2013158978 Oct 2013 WO
2013158983 Oct 2013 WO
2013166293 Nov 2013 WO
Non-Patent Literature Citations (186)
Entry
Finding lost wrenches: Using continuum robots for contact detection and estimation of contact location Bajo, A.; Simaan, N. Robotics and Automation (ICRA), 2010 IEEE International Conference on DOI: 10.1109/ROBOT.2010.5509569; Publication Year: 2010, pp. 3666-3673; Cited by: Papers (7).
Bajo, A., Goldman, R. E., Wang, L., Fowler, D. & Simaan, N (2012). Integration and Preliminary Evaluation of an Insertable Robotic Effectors Platform for Single Port Access Surgery. In International Conference on Robotics and Automation (ICRA'2012), pp. 3381-3387.
Bajo, A., Pickens, R. B., Herrell, D. S. & Slmaan, N (2012). A Pilot Ex-Vivo Evaluation of a Telerobotic System for Transurethral Intervention and Surveillance. In Hamlyn Symposium on Medical Robotics.
Bajo, A., Pickens, R. B., Herren, D. S. & Simaan, N (2013). Constrained Motion Control of Multisegment Continuum Robots for Transurethral Bladder Resection and Surveillance. In Accepted for publication in IEEE International Conference on Robotics and Automation (ICRA'2013).
A. Kapoor, K. Xu, W. Wei, N. Simaan, and R. Taylor, “Telemanipulation of Snake-Like Robots for Minimally Invasive Surgery of the Upper Airway,” in MICCAI 2006 workshop on medical robotics, 2006.
A. Kapoor, N. Simaan, and P. Kazanzides, “A System for Speed and Torque Control of DC Motors with Application to Small Snake Robots,” 2004.
A. Kapoor, N. Simaan, and R. Taylor, “Suturing in Confined Spaces: Constrained Motion Control of a Hybrid 8-DoF Robot”, in IEEE Conference on Advanced Robotics, 2005, pp. 452-459.
Abbott, J., Marayong, P., and Okamura, A. M. Haptic virtual fixtures for robot-assisted manipulation. Robotics Research 28, Aug. 2007, 49-64.
Alexander T. Hillel, Ankur Kapoor, Nabil Simaan, Russell H. Taylor and Paul Flint, “Applications of Robotics for Laryngeal Surgery,” Otolaryngologic Clinics of North America, Nasir Bhatti & Ralph P. Tufano Eds., vol. 41, Issue 4, pp. 781-791, doi:0.1016/j.otc.2008.01.021, Aug. 2008.
Chen, Y., Zhang, J., Wang, H., Garty, G., Xu, Y., Lyulko, O., Turner, H., Randers-Pehrson, G., Simaan, N., Yao, L., Brenner, D., “Development of a Robotically-based Automated Biodosimetry Tool for Highthroughput Radiological Triage,” accepted in International Journal of Biomechatronics and Biomedical Robotics (IJBBR), vol. 1, No. 2 pp. 115-125, 2010.
Debus, T., Dupont, P., and Howe, R. Contact State Estimation using Multiple Model Estimation and Hidden Markov Models. 2The International Journal of Robotics Research 23, 4-5 (2004), 399-413.
Ding, J., Xu, K., Goldman, R. E., Allen, P. K, Fowler, D. L., and Simaan, N. “Design, Simulation and Evaluation of Kinematic Alternatives for Insertable Robotic Effectors Platforms in Single Port Access Surgery,” In 2010 IEEE International Conference on Robotics and Automation (Anchorage, AK, 2010), pp. 1053-1058.
Godage, Isuru S. et al., “Shape Function-Based Kinematics and Dynamics for Variable Length Continuum Robotic Arms,” 2011 IEEE International Conference on Robotics and Automation (May 9-13, 2011).
R. E. Goldman, A. Bajo, and N. Simaan, “Compliant Motion Control for Continuum Robots with Intrinsic Actuation Sensing,” in IEEE International Conference on Robotics and Automation, 2011, pp. 1126-1132.
Gravagne, Ian A. and Ian D. Walker, “Manipulability, Force, and Compliance Analysis for Planar Continuum Manipulators,” IEEE Transactions on Robotics and Automation, vol. 18, No. 3 (Jun. 2002).
Gravagne, Ian A. et al, “Good Vibrations: A Vibration Damping Setpoint Controller for Continuum Robots,” Proceedings of the 2001 IEEE International Conference on Robotics & Automation (May 21-26, 2001).
Hamid, S. A. & Simaan, N (2009). Design and Synthesis of Wire-Actuated Universal-Joint Wrists for Surgical Applications. In 2009 IEEE International Conference on Robotics and Automation, pp. 1807-1831. Kobe, Japan.
Hannan, M. W., and Walker, I. D. Kinematics and the Implementation of an Elephant's Trunk Manipulator and Other Continuum Style Robots. Journal of Robotic Systems 20, 2 (2003), 45-63.
Hayward, Vincent, “Fast Collision Detection Scheme by Recursive Decomposition of a Manipulator Workspace,” Proceedings IEEE International Conference on Robotics and Automation, vol. 3 (1986).
Hogan, N. Impedance Control: An Approach to Manipulation: Part lTheory. Journal of Dynamic Systems, Measurement, and Control 107, 1 (1985), 1.
International Search Report and Written Opinion for PCT Application No. PCT/US2013/037346 dated Aug. 27, 2013.
J. Ding, K. Xu, R. Goldman, P. Allen, D. Fowler, and N. Simaan, “Design, Simulation and Evaluation of Kinematic Alternatives for Insertable Robotic Effectors Platforms in Single Port Access Surgery.” pp. 1053-1058, 2010.
J. J. Abbott and A. M. Okamura, “Stable Forbidden-Region Virtual Fixtures for Bilateral Telemanipulation,” vol. 128, No. 1, pp. 53-64, 2006.
J. Zhang, S. Bhattacharyya, and N. Simaan, “Model and Parameter Identification of Friction During Robotic Insertion of Cochlear-Implant Electrode Arrays,” in IEEE International Conference on Robotics and Automation, 2009, pp. 3859-3864.
Jones, Bryan A., “Kinematics for Multisection Continuum Robots,” IEEE Transactions on Robotics, vol. 22, No. 1 (Feb. 2006).
N. Xu and N. Simaan, “Actuation Compensation for Flexible Surgical Snake-like Robots with Redundant Remote Actuation,” in IEEE International Conference on Robotics and Automation, 2006, pp. 4148-4154.
K. Xu and N. Simaan, “Analytic Formulation for Kinematics, Statics and Shape Restoration of Multibackbone Continuum Robots via Elliptic Integrals,” ASME Journal of Mechanisms and Robotics (JMR), vol. 2, pp. 11006-11013, 2010.
K. Xu, R. Goldman, J. Ding, P. Allen, D. Fowler, and N. Simaan, “System Design of an Insertable Robotic Effector Platform for Single Port Access (SPA) Surgery,” in IEEE/RSJ International Conference on Intelligent Robots and Systems, 2009, pp. 5546-5552.
K. Xu and N. Simaan, “An Investigation of the Intrinsic Force Sensing Capabilities of Continuum Robots,” IEEE Transactions on Robotics (TRO), vol. 23, No. 3 (Jun. 2008).
Mahvash, Mohsen and Pierre E. Dupont, “Stiffness Control of a Continuum Manipulator in Contact with a Soft Environment,” The 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (Oct. 18-22, 2010).
Mahvash, Mohsen and Pierre E. Dupont, “Stiffness Control of Surgical Continuum Manipulators,” IEEE Transactions on Robotics, vol. 27, No. 2 (Apr. 2011).
N. Simaan, A. Bajo, A. Reiter, L. Wang, P. Allen, and D. Fowler, “Lessons learned using the insertable robotic effector platform (IREP) for single port access surgery,” Journal of Robotic Surgery, Apr. 2013.
N. Simaan, “Snake-Like Units Using Flexible Backbones and Actuation Redundancy for Enhanced Miniaturization,” In 2005 IEEE International Conference on Robotics and Automation (Barcelona, Spain, 2005), IEEE, pp. 3023-3028.
N. Simaan, Russell H. Taylor, Paul Flint, “High Dexterity Snake-like Robotic Slaves for Minimally Invasive Telesurgery of the Upper Airway,” MICCAI 2004 (7th International Conference on Medical Image Computing and Computer-Assisted Intervention), pp. 17-24, vol. 2, Saint Malo, France, Sep. 26-30, 2004.
Simaan, N., Glozman, D. & Shoham, M (1998). Design Considerations of New Six Degrees-Of-Freedom Parallel Robots. In IEEE International Conference on Robotics and Automation (ICRA'1998), pp. 1327-1333.
Simaan, N. (1999). Analysis and Synthesis of Parallel Robots for Medical Applications. Master Thesis. Technion-Israel Institute of Technology, Haifa, Israel.
N. Simaan, Task-Based Design and Synthesis of Variable Geometry Parallel Robots (2002). Phd Thesis, Technion-Israel Institute of Technology, Haifa, Israel.
Pickens, R. B., Bajo, A., Simaan, N. & Herrell, S. D (2012). Preliminary Testing of a Transurethral Dexterous Robotic System for Bladder Resection. In 27th EUS Annual Meeting, pp. 65. Atlanta, GA.
Pile, J., Cheung, M.-Y., Zhang, J. & Simaan, N (2011). Algorithms and Design Considerations for Robot Assisted Insertion of Perimodiolar Electrode Arrays. In 2011 IEEE International Conference on Robotics and Automation. Shanghai, China.
R. Taylor et al., “Steady-hand robotic system for microsurgical augmentation,” International Journal of Robotics Research, vol. 18, No. 12, pp. 1201-1210, 1999.
Reiter, A., Bajo, A., Iliopoulos, K., Simaan, N., and Allen, P. K. Learning-Based Configuration Estimation of a Multi-Segment Continuum Robot. In the Fourth IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics (Roma, Italy, 2012), p. accepted.
Reiter, A., Goldman, R. E., Bajo, A., Iliopoulos, K., Simaan, N., and Allen, P. K. A Learning Algorithm for Visual Pose Estimation of Continuum Robots. In 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems (San Francisco, CA, USA, 2011), pp. 2390-2396.
Rivera-Serrano, C. M., Johnson, P., Zubiate, B., Kuenzler, R., Choset, H., Zenati, M., Tully, S., and Duvvuri, U. A transoral highly flexible robot: Novel technology and application. The Laryngoscope 122, 5 (May 2012), 1067-71.
Sen, T. H., Deshmukh, N., Roger E, .. G., Kazanzides, P., Taylor, R. H., Boctor, E. et al (2012). Enabling technologies for natural orifice transluminal endoscopic surgery (N.O.T.E.S) using robotically guided elasticity imaging. In Proceeding of SPIE Medical Imaging 2012, pp. 83161Y1-83161Y8.
Tully, S., Bajo, A., Kantor, G., Choset, H., and Simaan, N. Constrained Filtering with Contact Detection Data for the Localization and Registration of Continuum Robots in Flexible Environments. In 2012 IEEE International Conference on Robotics and Automation (St. Paul, MI USA, 2012).
W. Wei, K. Xu, and N. Simaan, “A compact Two-armed Slave Manipulator for Minimally Invasive Surgery of the Throat,” in IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics, 2006, pp. 769-774.
Wei, W., Goldman, R. E., Simaan, N., Fine, H. & Chang, S (2007). Design and Theoretical Evaluation of Micro-Surgical Manipulators for Orbital Manipulation and Intraocular Dexterity. In 2007 IEEE International Conference on Robotics and Automation, pp. 3389-3395. Roma, Italy.
Wei, W., and Simaan, N. Modeling, Force Sensing, and Control of Flexible Cannulas for Microstent Delivery. Journal of Dynamic Systems, Measurement, and Control 134, 4 (2012), 041004.
Wei, W., Popplewell, C., Fine, H., Chang, S., Simaan, N., “Enabling Technology for Micro-Vascular Stenting in Ophthalmic Surgery,” ASME Journal of Medical Devices (JMED), vol. 4, Issue 1, 014503 (6 pages) doi:10.1115/1.4001193, 2010.
U.S. Office action for U.S. Appl. No. 13/891,389 dated Jan. 2, 2015.
International Search Report and Written Opinion for PCT Application No. PCT/US2013/021167 dated Mar. 22, 2013.
International Search Report and Written Opinion for PCT Application No. PCT/US2013/037336 dated Jul. 25, 2013.
International Search Report and Written Opinion for PCT Application No. PCT/US2013/037353 dated Aug. 19, 2013.
International Search Report and Written Opinion for PCT Application No. PCT/US2013/039280 dated Aug. 20, 2013.
Reichert, S., Zhang, J., Xu, K, Simaan, N. & Manolidis, S (2007). Robotic insertion of cochlear implant electrodes to minimize cochlear trauma. In 6th European Congress of Oto-Rhino-Laryngology, Head and Neck Surgery., Vienna, 4ustria, Jun. 2007.
Robinson, G., and Davies, J. Continuum robots—a state of the art. In 1999 IEEE International Conference on Robotics and Automation (Detroit, MI, USA, 1999), vol. 4, leee, pp. 2849-2854.
Roland, J. T., Zhang, J., Manolidis, S. & Simaan, N (2009). Progress Towards a Robotically Inserted Cochlear Implant Electrode. In 12th Symposium on Cochlear Implants in Children, Seattle.
Rosenberg, L. Virtual fixtures: Perceptual tools for telerobotic manipulation. In Proceedings of IEEE Virtual Reality 4nnual International Symposium (1993) pp. 76-82.
Rucker, D. C., and Webster, III, R. J. Deflection-Based Force Sensing for Continuum Robots: A Probabilistic Approach. In 2011 IEEE/RSJ Inter-national Conference on Intelligent Robots and Systems (2011), pp. 3764-3769.
Rucker, D. C., Jones, B. A., and Webster III, R. J. A Geometrically Exact Model for Externally Loaded Concentric-Tube Continuum Robots. IEEE Transaction on Robotics 26,5 (2010), 769-780.
S. J. Harris, W. J. Lin, R. D. Hibberd, J. Cobb, R. Middelton, and B. L. Davies, “Experiences with Robotic Systems for <nee Surgery,” vol. 1205, J. Troccaz, E. Grimson, and R. Mosges, Eds. Springer, 1997, pp. 757-766.
Saito, S. Transurethral en bloc resection of bladder tumors. The Journal of urology 166,6 (Dec. 2001), 2148-50.
Salerno, A., Zhang, J., Bhatla, A., Lyulko, O. V., Nie, J., Dutta, A. et al (2007). Design Considerations for a Minimally Invasive High-Throughput Automation System for Radiation Biodosimetry. In IEEE Conference on Automation Science and Engineering, pp. 846-852. Scottsdale, AZ, USA.
Salisbury, J. Active stiffness control of a manipulator in cartesian coordinates. In 1980 19th IEEE Conference on Decision and Control including the Symposium on Adaptive Processes (1980), pp. 95-100.
Seibold, U., Kubler, B., and Hirzinger, G. Prototype of Instrument for Minimally Invasive Surgery with 6-Axis Force Sensing Capability. In Proceedings of the 2005 IEEE International Conference on Robotics and Automation (Barcelona, Spain, 2005), 496-501, Ed., IEEE, pp. 496-501.
Sentis, L., Park, J., and Khatib, O. Compliant Control of Multicontact and Center-of-Mass Behaviors in Humanoid Robots. IEEE Transactions on Robotics 26, 3 (Jun. 2010), 483-501.
Shen, J.-H., Yu, Fl, Simaan, N. & Joos, K M. (2013). A Robotic-controlled Intraocular OCT Probe. In 2013 The Association for Research in Vision and Ophthalmology Annual Conference (ARVO'2013).
Siciliano, B., Sciavicco, L., Villani, L., and Oriolo, G. Robotics: Modelling, Planning, and Control. 2009.
Su, H., Cardona, D. C., Shang, W., Camilo, A., Cole, G. A., Rucker, D. C., Webster, R. J., and Fischer, G. S. A MRI-Guided Concentric Tube Continuum Robot with Piezoelectric Actuation: A Feasibility Study. In 2012 IEEE International Conference on Robotics and Automation (St. Paul, MN USA, 2012), no. May.
Taylor, R., Jensen, P., Whitcomb, L., Barnes, A., Kumar, R., Stoianovici, D., Gupta, P., Wang, Z., DeJuan, E., and Kavoussi, L. A Steady-hand robotic system for microsurgical augmentation. International Journal of Robotics Research 18, 12 (1999), 1201-1210.
Torres, L G., and Alterovitz, R. Motion Planning for Concentric Tube Robots Using Mechanics-based Models. In 2011 IEEE/RSJ International Con-ference on Intelligent Robots and Systems (San Francisco, CA, USA, 2011), pp. 5153-5159.
Ukai, R., Kawashita, E., and Ikeda, H. A new technique for transurethral resection of superficial bladder tumor in 1 piece. The Journal of Urology2 163, 3 (2000), 878-879.
Valdastri, P., Harada, K, Menciassi, A., Beccai, L., Stefanini, C., Fujie, M., and Dario, P. Integration of a miniaturised triaxial force sensor in a minimally invasive surgical tool. IEEE transactions on biomedical engineering 53, 11 (Nov. 2006), 2397-400.
W. Wei, R. Goldman, H. Fine, S. Chang, and N. Simaan, “Design and Dexterity Evaluation for a Dual-Arm Micro-Surgical Robotic System for Orbital Manipulation and Intraocular Dexterity,” IEEE Transactions on Robotics, vol. 25, No. 1, pp. 147-157, 2009.
Wagner, C. R., Stylopoulos, N., Jackson, P. G., and Howe, R. D. The Benefits of Force Feedback in Surgery: Examination of Blunt Dissection. Presence: Teleoperators and Virtual Environments 16, 3 (2007), 252-262.
Webster III, R. J., Romano, J. M., and Cowan, N. J. Mechanics of Precurved-Tube Continuum Robots. IEEE Transaction on Robotics 25, 1 (2009), 67-78.
Webster III, R. J., and Jones, B. A. Design and Kinematic Modeling of Constant Curvature Continuum Robots: A Review. The International Journal of Robotics Research (Jun. 2010).
Wei Tech, A., Khosla, P., and Riviere, C. An Intelligent Hand-Held Microsurgical Instrument for Improved Accuracy. In 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Istanbul, Turkey, 2001), pp. 25-28.
Wei, W., Goldman, R., Fine, H., Chang, S., Simaan, N., “Performance Evaluation for Multi-Arm Manipulation of Hollow Suspended Organs,” IEEE Transactions on Robotics, vol. 25, No. 1, pp. 147-157, doi 10.1109/TRO.2008.2006865, 2009.
Wei, W, Simaan N., “Design of Planar Parallel Robots With Preloaded Flexures for Guaranteed Backlash Prevention,” ASME Journal of Mechanisms and Robotics (JMR), doi:10.1115/1.4000522, vol. 2, No. 1, pp. 011012-1 to 011012-10, 2010.
Wei, W. (2010). Design and Implementation of High-Precision Hybrid Robotic Systems with Application for Ophthalmic Micro-Surgery. Phd Thesis, Department of Mechanical Engineering, Columbia University, New York City, NY.
Wei, W., Fine, H., Chang, S. & Simaan, N (2010). A Pilot Study on Using a Flexible Cannula Robot for Micro-Vascular Stenting. In IEEE International Conference on Robotics and Automation Workshop on Snakes, Worms and Catheters: Continuum and Serpentine Robots for Minimally Invasive Surgery, IEEE International Conference on Robotics and 4utomation, May 3.
Weinstein, G. S., O'Malley, B. W., Magnuson, J. S., Carroll, W. R., Olsen, K. D., Daio, L., Moore, E. J., and Holsinger, F. C. Transoral robotic surgery: A multicenter study to assess feasibility, safety, and surgical margins. The Laryngoscope (Jul. 2012), 1-7.
Whitney, D. E. Force Feedback Control of Manipulator Fine Motions. Journal of Dynamic Systems, Measurement, and Control 99, 2 (1977), 91.
Whitney, D. E. Resolved Motion Rate Control of Manipulators and Human Prostheses. IEEE Transaction on Man-Machine Systems MMS-10, 2 (Jun. 1969), 47-53.
Yoshikawa, T. Force Control of Robot Manipulators. In 2000 IEEE International Conference on Robotics and Automation (San Francisco, CA, USA, 2000), no. Apr., pp. 220-226.
Yu, H., Shen, J. H., Joos, K. M. & Simaan, N (2013). Design, Calibration and Preliminary Testing of A Robotic Telemanipulator for OCT guided Retinal Surgery. In Accepted for publication in IEEE International Conference on Robotics and Automation (ICRA2013).
Zhou, J., Shen, X., Petriu, E. M., and Georganas, N. D. Linear Velocity and Acceleration Estimation of 3 DOF Haptic Interface. In IEEE International Workshop on Haptic Audio Visual Environments and their Application (HAVE 2008) (Ottawa, Canada, 2008), pp. 137-142.
A. Bajo and N. Simaan, “Configuration and Joint Feedback for Enhanced Performance of Multi-Segment Continuum Robots,” in IEEE International Conference on Robotics and Automation, 2011, pp. 2905-2912.
A. Bajo, and N. Simaan, Kinematics-Based Detection and Localization of Contacts Along Multisegment Continuum Robots. IEEE Transactions on Robotics 28,2 (Apr. 2012), 291-302.
R.E. Goldman, A. Bajo, and N. Simaan, Compliant Motion Control for Continuum Robots with Intrinsic Actuation Sensing. In 2011 IEEE International Conference on Robotics and Automation (Shanghai, China, 2011), pp. 1126-1132.
Bajo, A., Dharamsi, L., Netterville, J. L., Garrett, G. C., and Simaan, N (2013). Robotic-Assisted Micro-Surgery of the Throat: the Trans-Nasal Approach. In Accepted for publication in IEEE International Conference on Robotics and 4utomation (ICRA'2013).
A. Kapoor, M. Li, and R. H. Taylor, “Spatial Motion Constraints for Robot Assisted Suturing using Virtual Fixtures,” 2005, vol. 3750, pp. 89-96.
A. Kapoor and R.H. Taylor, A Constrained Optimization Approach to Virtual Fixtures for Multi-Handed Tasks. In IEEE International Conference on Robotics and Automation (Pasadena, CA, 2008), pp. 3401-3406.
Agrawal, V., Peine, W. J., Yao, B., and Choi, S. Control of Cable Actuated Devices using Smooth Backlash Inverse. In 2010 IEEE International Conference on Robotics and Automation (Anchorage, AK, 2010), pp. 1074-1079.
Angeles, J. Automatic Computation of the Screw Parameters of Rigid-Body Motions. Part II: Infinitesimally-Separated Positions. Journal of Dynamic Systems, Measurement, and Control 108, Mar. (1986), 32-38.
Baki, P., Szekely, G., and Kosa, G. Miniature tri-axial force sensor for feedback in minimally invasive surgery. In 2012 4th IEEE RAS & EMBS In-ternational Conference on Biomedical Robotics and Biomechatronics (BioRob) (Roma, Italy, Jun. 2012), IEEE, pp. 805-810.
Bhattacharyya, S. (2011). Motion Planning and Constraint Exploration for Robotics Surgery. Master Thesis, Vanderbilt University, Nashville, TN.
Bhattacharyya, S. & Simaan, N (2013). Characterization of Constraints in Flexible Unknown Environments. In Accepted for publication in IEEE International Conference on Robotics and Automation (ICRA2013).
Birkfellner, W., Watzinger, F., Wanschitz, F., Ewers, R., and Bergmann, H. Calibration of tracking systems in a surgical environment. IEEE Transactions on Medical Imaging 17,5 (Oct. 1998), 737-42.
Bokelberg, E. H., Hunt, K. H., and Ridley, P. R. Spatial Motion-I: Points of inflection and the differential geometry of screws. Mechanism and Machine Theory 27,1 (1992), 1-15.
Burgner, J., Swaney, P. J., Rucker, D. C., Gilbert, H. B., Nill, S. T., Russell III, P. T. R., Weaver, K. D., Iii, R. J. W., Russell, P. T., and Webster, R. J. A Bimanual Teleoperated System for Endonasal Skull Base Surgery. In 2011 IEEE International Conference on In-telligent Robots and Systems (San Francisco, CA, Sep. 2011), IEEE, pp. 2517-2523.
Camarillo, D. B., Carlson, C. R., and Salisbury, J. K. Configuration Tracking for Continuum Manipulators With Coupled Tendon Drive. IEEE Transactions on Robotics 25,4 (Aug. 2009), 798-808.
Camarillo, D. B., Milne, C. F., Carlson, C. R., Zinn, M. R., and Salisbury, J. K. Mechanics Modeling of Tendon-Driven Continuum Manipulators. IEEE Transaction on Robotics 24,6 (2008), 1262-1273.
Camarillo, D. B., Loewke, K., Carlson, C. R., and Salisbury, J. K Vision based 3-D shape sensing of flexible manipulators. In 2008 IEEE International Conference on Robotics and Automation (Pasadena, CA, 2008), pp. 2940-2947.
Cauberg, E. C., de la Rosette, J. J., and de Reijke, T. M. How to improve the effectiveness of transurethral resection in nonmuscle invasive bladder cancer? Current Opinion in Urology 2 19,5 (2009), 504-510.
Chan, T. F., and Dubey, R. V. A Weighted Least-Norm Solution Based Scheme for Avoiding Joint Limits for Redundant Joint Manipulators. IEEE Transaction on Robotics and Automation 11,2 (1995), 286-292.
Chirikjian, G. S., and Burdick, J. W. A Modal Approach to Hyper-Redundant Manipulator Kinematics. IEEE Transaction on Robotics and Au-tomation 10, 3 (1994), 343-354.
Chirikjian, G. S., and Burdick, J. W. An obstacle avoidance algorithm for hyper-redundant manipulators. In Jroceedings., IEEE International Conference on Robotics and Automation (1990), IEEE Comput. Soc. Press, pp. 625-531.
Croom, J. M., Rucker, D. C., Romano, J. M., and Webster, R. J. I. Visual Sensing of Continuum Robot Shape Using Self-Organizing Maps. in 2010 IEEE International Conference on Robotics and Automation (Anchorage, AK, 2010), pp. 4591-4596.
De Luca, A., Haddadin, S., and Hirzinger, G. Collision Detection and Safe Reaction with the DLR-III Lightweight Manipulator Arm. In 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems (Beijing, China, 2006), pp. 1623-1630.
De Luca, A., and Manes, C. Modeling of Robots in Contact with a Dynamic Environment. IEEE Transaction on Robotics and Automation 10,4 (1994), 542-548.
Degani, A., Choset, H., Wolf, A., and Zenati, M. A. Highly Artic-ulated Robotic Probe for Minimally Invasive Surgery. In 2006 IEEE Inter- national Conference on Robotics and Automation (Orlando, FL, USA, 2006), pp. 4167-4172.
Dimaio, S. da Vinci and Beyond. In 2010 IEEE International Conference on Robotics and Automation Workshop on Vledical Cyber-Physical Systems (Anchorage, AK, 2010).
Ding, J., Goldman, R. E., Xu, K., Allen, P. K, Fowler, D. L., and Simaan, N. Design and Coordination Kinematics of an Insertable Robotic Effectors Platform for Single-Port Access Surgery. Ieeeiasme Transactions on Vlechatronics (2012), 1-13.
Dupont, P., Lock, J., Itkowitz, B., and Butler, E. Design and Control of Concentric-Tube Robots. IEEE Transaction on Robotics 26,2 (2010), 209-225.
Eberman, B. S., and Salisbury, J. K. Determination of Manipulator Contact Information from Joint Torque Vleasurements. In Experimental Robotics I, vol. 139. Springer, 1990, pp. 463-473.
Featherstone, R. Modeling and Control of Contact Between Constrained Rigid Bodies. IEEE Transaction on Robotics and Automation 20,1 (2004), 82-92.
Featherstone, R., Thiebaut, S. S., and Khatib, O. A General Contact Model for Dynamically-Decoupled Force/Motion Control. In 1999 IEEE International Conference on Robotics and Automation (1999), no. May, pp. 3281-3286.
Fine, H., Wei, W., Simaan, N., “Could Robots Ever Do Retina Surgery? ,” Review of Ophthalmology, vol. 17, No. 5, Issue: May 1, 2010.
Fine, H., Wei, W., Chang, S. & Simaan, N (2009). A novel dual-arm dexterous ophthalmic microsurgical robot: applications for retinal vascular cannulation and stent deployment. In American Society of Retinal Specialists, Retina congress 2009, New York, NY, Sep. 4-Oct. 4.
Garty, G., Randers-Pehrson, G., Simaan, N., Salerno, A., A., D., J., N. et al (2007). Development of an ultrahigh-throughput robotically-based biodosimetry workstation using in-situ assays. In 13th International Congress of Radiation Research, San Francisco, California, Jul. 8-12, 2007.
J. Zhang and N. Simaan, “Optimal Design of Under-actuated Steerable Electrode Arrays for Optimal Insertions,” ASME Journal on Mechanisms and Robotics, Submitted, 2010.
J. Zhang, K. Xu, N. Simaan, and S. Manolidis, “A Pilot Study of Robot-Assisted Cochlear Implant Surgery Using Steerable Electrode Arrays,” in International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI '06), 2006, pp. 33-40.
Goldman, R. E. (2011). Analysis, Algorithms, and Control for Intelligent Surgical Exploration and Intervention. Phd Thesis, Columbia University (graduated with distinction).
Goldman, R. E., Bajo, A., Suh, L., Benson, M. & Simaan, N (2011). Rapidly Deployable Telerobotic Slave for Transurethral Exploration and Intervention. In presented in the 2011 Annual Engineering and Urology Society annual meeting, May 14, Washington, DC.
Goldman, R. E., Bajo, A. & Simaan, N. (2013). Algorithms for Autonomous Exploration and Estimation in Compliant Environments. Robotica, 31(1), 71-88.
Goldman, R. E., Bajo, A., MacLachlan, L. S., Pickens, R., Herrell, S. D. & Simaan, N. (2013). Design and Performance Evaluation of a Minimally Invasive Telerobotic Platform for Transurethral Surveillance and Intervention. IEEE Transactions on Biomedical Engineering, 60(4), 918-925.
Gravagne, I. A., and Walker, I. D. Kinematic Transformations for Remotely-Actuated Planar Continuum Robots in 2000 IEEE International Conference on Robotics & Automation (San Francisco, 2000), no. April, pp. 19-26.
Guthart, G., and Salisbury, K. The IntuitiveTM Telesurgery System: Overview and Application. In 2000 IEEE International Conference on Robotics and Automation (2000), pp. 618-621.
Haddadin, S., De Luca, A., and Hirzinger, G. Collision Detection and Reaction: A Contribution to Safe Physical Human-Robot Interaction. In 2008 Ieeejrsj International Conference on Intelligent Robots and Systems (Nice, France, 2008), pp. 3356-3363.
Herrell SD, Kwartowitz DM, Milhoua PM, Galloway RL. Toward Image-Guided Robotic Surgery: System Validation. J Urol. Feb. 2009; 181(2): 783-9 Discussion 789-90. Epub Dec. 16, 2008.
Ho, S. C., Hibberd, R. D., and Davies, B. L. Robot Assisted Knee Surgery. IEEE Engineering in Medicine and Biology Magazine 14, 3 (1995), 292-299.
Howell, L L. Compliant Mechanisms. Wiley-Interscience, 2001.
Ikits, M., Brederson, J. D., Hansen, C. D., and Hollerbach, J. M. An Improved Calibration Framework for Electromagnetic Tracking Devices. In 2001 IEEE Virtual Reality (Yokohama, Japan, 2001), IEEE Comput. Soc, pp. 63-70.
Ikuta, K., Yamamoto, K., and Sasaki, K Development of remote micro- surgery robot and new surgical procedure for Jeep and narrow space. In 2003 IEEE International Conference on Robotics and Automation (Taipei, Taiwan, 2003), vol. 1, IEEE, pp. 1103-1108.
J. Zhang, S. Manolidis, T. J. Roland, and N. Simaan, “Path Planning and Workspace Determination for Robot-Assisted nsertion of Steerable Electrode Arrays for Cochlear Implant Surgery,” 2008.
J. Zhang, T. J. Roland, S. Manolidis, and N. Simaan, “Optimal Path Planning for Robotic Insertion of Steerable Electrode Arrays in Cochlear Implant Surgery,” ASME Journal of Medical Devices, vol. 3, no. 1, 2009.
Zhang, J., Wei, W., Ding. J., Rolant, T.J., Manolidis, S., Simaan, N., “Inroads towards Robot-Assisted Cochlear Implant Surgery using Steerable Electrode Arrays”, Otology & Neurology special issue on Cochlear Implants, doi: 1097/MAO.0b013e3181e7117e, 2010.
Zhang, J. (2010). Design of Steerable Electrode Arrays and Optimal Insertion Path Planning for Robot-Assisted Cochlear Implant Surgeries. Phd Thesis, Department of Mechanical Engineering, Columbia University, New York City, NY.
Jones, B. A., and Walker, I. D. Kinematics for Multisection Continuum Robots. IEEE Transactions on Robotics 22, 1 (Dec. 2006), 43-57.
K. Xu and N. Simaan, “Intrinsic Wrench Estimation and Its Performance Index for Multisegment Continuum Robots,” IEEE Transactions on Robotics, vol. 26, No. 3, pp. 555-561, Jun. 2010.
Xu, K. (2009). Design, Modeling and Analysis of Continuum Robots as Surgical Assistants with Intrinsic Sensory Capabilities. Phd Thesis, Columbia University).
Xu, K., Qiu, D. & Simaan, N (2011). A Pilot Investigation of Continuum Robots as a Design Alternative for Upper Extremity Exoskeletons. In IEEE International Conference on Robotics and Biomimmetics (ROBIO'2011), pp. 656-662.
Kesner, S. B., and Howe, R. D. Design and Control of Motion Compensation Cardiac Catheters. In 2010 IEEE ntemational Conference on Robotics and Automation (Anchorage, AK, 2010), pp. 1059-1065.
Kesner, S. B., and Howe, R. D. Force Control of Flexible Catheter Robots for Beating Heart Surgery. In 2011 IEEE ntemational Conference on Robotics and Automation (Shanghai, China, Jan. 2011), pp. 1589-1594.
Kesner, S. B., Howe, R. D., and Member, S. Position Control of Motion Compensation Cardiac Catheters. IEEE Transaction on Robotics 27, 6 (2011), 1045-1055.
Khatib, O. A Unified Approach for Motion and Force Control of Robot Manipulators: The Operational Space Formulation. IEEE Journal of Robotics and Automation 3,1 (1987), 43-53.
Kragic, D., Marayong, P., Li-Ming Su, Okamura, A. M., and Hager, G. D. Human-Machine Collaborative Systems for Microsurgical Applications. The International Journal of Robotics Research 24, 9 (Sep. 2005), 731-741.
Kwartowitz DM, Miga MI, Herrell SD, Galloway RL. Towards Image Guided Robotic Surgery: Multi-Arm Tracking Through Hybrid Localization. Int J Comput Assist Radio! Surg. May 2009;4(3):281-6. Epub Mar. 19, 2009.
L. B. Rosenberg, “Virtual fixtures: Perceptual tools for telerobotic manipulation,” in Proceedings of IEEE Virtual Reality Annual International Symposium, 1993, pp. 76-82.
Lawson, G., Matar, N., Remade, M., Jamart, J., and Bachy, V. Transoral robotic surgery for the management of head and neck tumors: learning curve. European archives of oto-rhino-laryngology: official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS): affiliated with the German Society for Oto-Rhino-Laryngology—Head and Neck Surgery 268, 12 (Dec. 2011), 1795-801.
Lipkin H., and Duffy, J. Hybrid Twist and Wrench Control for a Robotic Manipulator. Transaction of the ASME 110 (1988), 138-144.
Lock, J., and Dupont, P. E. Friction Modeling in Concentric Tube Robots. In 2011 IEEE International Conference on Robotics and Automation (Shanghai, China, Jan. 2011), pp. 1139-1146.
Lumelsky V. J., and Cheung, E. Real-Time Collision Avoidance in Tele-operated Whole-Sensitive Robot Arm Manipulators. IEEE Transactions on Systems, Man, and Cybernetics 23,1 (1993), 194-203.
M. Li and R. H. Taylor, “Spatial Motion Constraints in Medical Robot Using Virtual Fixtures Generated by Anatomy,” 2004, pp. 1270-1275.
Ma, S., and Konno, M. An obstacle avoidance scheme for hyper-redundant manipulators-global motion planning in posture space. In Proceedings of Inter- national Conference on Robotics and Automation (1997), vol. 1, IEEE, pp. 161-166.
Mahvash, M., and Okamura, A. M. Friction Compensation for a Force-Feedback Telerobotic System. In 2006 IEEE International Conference on Robotics and Automation (Orlando, FL, 2006), no. May, pp. 3268-3273.
Mahvash, M., and Dupont, P. E. Mechanics of dynamic needle insertion into a biological material. IEEE transactions on bio-medical engineering 57, 4 (Apr. 2010), 934-43.
Mahvash, M., and Dupont, P. E. Stiffness Control of Surgical Continuum Manipulators. IEEE Transaction on Robotics 27, 2 (2011), 334-345.
Mason, M. T. Compliance and Force Control for Computer Controlled Manipulators. IEEE Transaction on Systems, Vlan, and Cybernetics smc-11, 6 (1981), 418-432.
Mason, M. T., and Salisbury, J. K Robot Hands and the Mechanics of Manipulation. MIT Press, Cambridge, MA, 1985.
Matsumoto, T., and Kosuge, K. Collision Detection of Manipulator Based on Adaptive Control Law. In 2001 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (Como, Italy, 2001), pp. 177-182.
N. Simaan, R. Taylor, and P. Flint, “A Dexterous System for Laryngeal Surgery—Multi-Backbone Bending Snake-like Slaves for Teleoperated Dexterous Surgical Tool Manipulation.” pp. 351-357, 2004.
N. Simaan, R. Taylor, P. Flint, and A. Hillel, “Minimally Invasive Surgery of the Upper Airways: Addressing the Challenges of Dexterity Enhancement in Confined Spaces,” Nova Scien, R. Faust, Ed. 2007, pp. 261-280.
N. Simaan, W. Wei, R. Goldman, H. Fine, and S. Chang, “A Dual-Arm Workstation for Intraocular Dexterity-Enhanced Microsurgery of the Eye and In-Organ Dexterity Enhancement and Manipulation of Suspended Organs,” 2006.
N. Simaan and M. Shoham, “Geometric Interpretation of the Derivatives of Parallel Robot's Jacobian Matrix with Application to Stiffness Control” ASME Journal of Mechanical Design, vol. 125, pp. 33-42., doi: 10.1115/1.1539514, 2003.
N. Simaan and M. Shoham, “Singularity Analysis of a Class of Composite Serial In-Parallel Robots,” IEEE transactions on Robotics and Automation, vol. 17, No. 3, pp. 301-311, doi:10.1109/70.938387 Jun. 2001.
N. Simaan and M. Shoham, “Stiffness Synthesis of a Variable Geometry Six Degrees-of-Freedom Double Planar Parallel Robot,” International Journal of Robotics Research (IJRR), vol. 22, No. 9, pp. 757 —775, doi: 10.1177/02783649030229005, Sep. 2003.
N. Simaan, K. Xu, W. Wei, A. Kapoor, P. Kazanzides, R. Taylor, P. Flint, “Design and Integration of a Telerobotic System for Minimally Invasive Surgery of the Throat,” International Journal of Robotics Research (IJRR) special issue on medical robotics. doi: 10.1177/0278364908104278, vol. 28, No. 9, 1134-1153, 2009.
Simaan, N., Manolidis, S. & Roland, J. T (2009). Inroads towards a robotically inserted CI electrode development. In 9th European Symposium of Paediatric Cochlear Implantation.
Simaan, N., Zhang, J., Roland, J. T. & Manolidis, S (2010). Steerable Continuum Robot Design for Cochlear Implant Surgery. In IEEE International Conference on Robotics and Automation Workshop on Snakes, Worms and Catheters: Continuum and Serpentine Robots for Minimally Invasive Surgery, May 3.
Simaan, N., Zhang, J., Roland, J. T. & Manolidis, S (2010). Robotic Study Shows that Insertion Speed Affects cochlear Implant Electrode Insertion Forces. In the 11th International Conference on Cochlear Implants and other Implantable Auditory Technologies, Stockholm, Sweden, Jun. 30-Jul. 3rd.
Simaan, N., Zhang, J., Roland, J. T. & Manolidis, S (2011). Robotic System for Steerable Cochlear Implant Insertion. In 2011 National Congress of the Italian Society of Audiology & Phoniatrics in Bari, Italy.
Simaan, N (2012). Design Considerations and Lessons Learned in Developing Systems for Single Port Access Surgery and Natural Orifice Surgery. In 34th international Conference on Engineering in Medicine and Biology Society (mini-symposium on Robotic Single-Port Surgery and Notes). San Diego, Aug. 27-31, 2012.
Simaan, N., Bajo, A., Reiter, A., Long, W., Allen, P. & Fowler, D. (2013). Lessons learned using the insertable robotic effector platform (IREP) for single port access surgery. Journal of Robotic Surgery.
Nakamura, Y. Advanced Robotics: Redundancy and Optimization. Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA, 1990.
Park, J., and Khatib, O. Robot Multiple Contact Control. Robotica 26, 05 (2008), 667-677.
Penning, R. S., Jung, J., Borgstadt, J. A., Ferrier, N. J., and Michael, R. Towards Closed Loop Control of a Continuum Robotic Manipulator for Medical Applications. In 2011 IEEE International Conference on Robotics and Automation (Shanghai, China 2011), pp. 4822-4827.
Petrovskaya, A., Park, J., and Khatib, O. Probabilistic Estimation of Whole Body Contacts for Multi-Contact Robot Control. In 2007 IEEE International Conference on Robotics and Automation (Rome, 2007), no. c, pp. 568-573.
Phee, S. J., Low, S. C., Sun, Z. L, Ho, K. Y., Huang, W. M., and Thant, Z. M. Robotic system for no-scar gastrointestinal surgery. The international journal of medical robotics + computer assisted surgery: MRCAS 4, 1 (Mar. 2008), 15-22.
Piccigallo, M., Scarfogliero, U., Quaglia, C., Petroni, G., Val-dastri, P., Menciassi, A., and Dario, P. Design of a Novel Bimanual Robotic System for Single-Port Laparoscopy. IEEE/ASME Transaction on Mechatronics 15, 6 (2010), 871-878.
Pile, J., Tsay, I. A., Dalton, J., Balachandran, R., Labadie, R. F. & Simaan, N (2012). Speed Dependence of Insertion Forces During CI Electrode Insertion. In Presented at the 12th Annual Conference on Cochlear Implants and other Implantable Auditory Technologies CI'2012, Baltimore, MD, May 3-5, 2012.
Pile, J. & Simaan, N (2013). Characterization of Friction and Speed Effects and Methods for Detection of Cochlear Implant Electrode Tip Fold-over. In Accepted for publication in IEEE International Conference on Robotics and Automation (ICRA'2013).
R.H. Sturges Jr and S. Laowattana, “A flexible, tendon-controlled device for endoscopy,” 1991, vol. 3, pp. 2582-2591.
Raibert, M. H., and Craig, J. J. Hybrid Position/Force Control of Manipulators. Journal of Dynamic Systems, Measurement, and Control 103, 2 (1981), 126.
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Provisional Applications (1)
Number Date Country
61819808 May 2013 US