The present invention relates to robotics and teleoperation and in particular it relates to a remotely actuated robotic wrist capable of transmitting a feedback force on an operator.
For example, the wrist can be used in Computer Aided Surgery, and particularly in mininvasive surgery, where the wrist can be mounted on a manipulator arm of a surgical robot remotely actuated by an operator (teleoperation surgery) or it can be used as distal component of a laparoscopic active instrument.
In the field of robotics and advanced teleoperation the problem is felt of a remotely actuated robotic wrist producing a feedback force on the operator. The desired features of a wrist for such an application are its easy construction, a relatively low cost and maximum operative flexibility of the wrist and of a possible distal member, in order to cover the maximum allowable degrees of freedom.
In one of the possible applications, the mininvasive surgery, it is necessary to carry out a surgical operation, for example in the abdomen or in the thorax of a patient, using small and thin instruments and an endoscope introduced in the human body, minimizing the size of the cut necessary to access the surgical site. The images detected by the endoscope are shown on a monitor where the surgeon can watch the surgical site in real time and execute the required operations.
One among the mininvasive techniques most common is the laparoscopy, whose success is due to the many advantages that it offers with respect to traditional surgery, such as less traumatic consequences on the patient, shorter hospitalization, and reduction of the risk of infections. Normally, mininvasive techniques also have the advantage of reducing the sanitary costs.
Mininvasive surgery can be effected successfully, either in a manual way, or with the aid of a robotic apparatus, also called slave, having manipulator arms remotely actuated by the surgeon through a special interface, also called master. This way, a surgeon acting on the master can carry out a surgical operation even at considerable distance from the patient where the slave holding the surgical instruments is arranged.
In the last few years different researches have developed the surgical instruments up to achieving high performances concerning reliability, precision and the safety of mininvasive operations.
In particular, surgical heads have been developed, to be mounted at the end of either an endoscope or a laparoscopic “trocar” for handling the tissues to treat in the abdomen of the patient.
Two main types exist of surgical heads for mininvasive operations.
A first type follows the principle of arranging the actuators (electric, hydraulic, pneumatic) and the possible sensorization of the head same. In this way the head is independent, so to say, from the external world, except from tendons that provide the control and feedback signals. This solution, however, is structurally complex concerning the assembling steps, is heavy and has high costs owing to the miniaturization of its components. In fact, the typical size of a head of this type is between 10 and 12 mm.
A second kind of surgical heads arranges the motors and sensors outside the head. This solution has different advantages among which a much easier assembling step owing to the lower number of components, low inertia, free choice of the actuators for the absence of housing constraints, as well as an easy sterilization, since the motors and the sensors are external. However, also the surgical robotic heads belonging to the latter kind have to be, in any case, systematically sterilized by specialized operators, and involve then high costs since the hospitals must obtain instruments in a larger amount in order not to await that the instruments to be sterilized are ready.
A milli-robotic head belonging at the second kind has been made by the Berkeley University. It has a structure very easy comprising two metal platforms united by a central spring that works as spherical hinge. The head woks with three tendons operated by corresponding motors, located out of the head same. The distal instrument extends from a central channel of the upper platform, whereas the CCD lenses, the optical fibres, and possible tubes for irrigating the tissues or for cauterization are arranged laterally. A type of robotic head of this kind has 2 degrees of freedom, and in particular two rotations with respect to axes normal to the axis of the instrument and the operation is redundant.
Various solutions have been presented for implementing also the rotation about the central axis, considered relevant by the surgeons since it allows to execute some essential manoeuvres, which otherwise would require torsions/rotations of the whole endoscope. A possible solution provides a central pulley operated by an additional tendon that causes the rotation of the upper platform. This result is achieved through a plurality of pulleys that orient the tendon. This solution, even if easy and functional, has limits due to the friction between the bushings where the tendons slide, and by the numerous pulleys necessary, which introduce relevant assembling problems given the small size of the head, about 10 mm.
A second solution provides a chain of platforms connected to each other through pivot joints. The operation of this mechanism is carried out through some tendons that pass through the holes of said platforms. Even in this case the solution is easy and reduces remarkably the costs, but friction occurs where the tendons slide on the surfaces of the holes. Normally, furthermore, the instruments presently existing do not allow the transmission of a feedback force on the surgeon, i.e. they are not capable to reflect “haptic” sensations relative to the contact. This affects the diffusion of robotic surgery, owing to the impossibility of transmitting to the surgeon such sensations, precluding control of the forces applied by the end effector on the tissues, thus increasing remarkably the risk of errors.
It is a feature of the present invention to provide a remotely actuated robotic wrist for robotic and teleoperation applications that provides a maximum flexibility.
It is a particular feature of the invention to provide such a remotely actuated robotic wrist suitable for supporting and manoeuvring an instrument for mininvasive surgical operations that is structurally easy and cost effective.
It is another feature of the present invention to provide a remotely actuated robotic wrist that allows three degrees of freedom of orientation of the instrument, or two degrees of freedom with the maximum coverage of the field of action of the same.
It is also a feature of the present invention to provide a robotic wrist that allows, in addition to the orientation, to manoeuvre the opening-closing action of the end effector, such as a gripper, a cutter, etc.
It is, furthermore, a feature of the present invention to provide a robotic wrist with a sufficiently precise feedback of the forces applied by the end effector through a return force on the operator, raising the rate of precision of the operation.
It is a further feature of the present invention to provide a robotic wrist suitable for a production of plastic material for a disposable application.
These and other features are accomplished with one exemplary remotely actuated robotic wrist according to the invention, whose characteristic is that it comprises:
Further characteristics of the invention are defined by the attached claims, according to independent claim 1.
The invention will now shown with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings wherein:
figures from 9 to the 12 show diagrammatically a perspective view of four possible positions of the robotic wrist of
figures from 13 to 16 show a perspective top plan view side view of a possible exemplary embodiment for generating the force and transmission of the movement used for operating the device of
In figures from 21 to 25 a diagrammatical view is shown of the kinematic operation of an alternative exemplary embodiment of the remotely actuated robotic wrist according to the invention;
In
A robotic wrist 1 comprises a distal member as an end effector 3 mounted on a support 2 pivotally connected to a central post 5 integral to a fixed base 4, for example by a ball joint 10 that allows three rotational degrees of freedom (
In particular, support 2 can be oriented with respect to central post 5 with a redundant actuating system, by arranging four forces F1-F4 in eccentric points P1-P4, for example by means of tendons 8, and causing support 2 to rotate about central post 5 by ball joint 10 (
The direction of application of forces F1-F4 is determined by connecting arms 7 (
In the exemplary embodiment of
In case the instrument mounted on the robotic wrist 1 has an opening/closing mechanism, such as a surgical gripper 3, between the instrument and the elongated portion 13 of ball joint 10 means with controlled yield 15a and 15b are provided (
More in detail, when tendons 8 are subject to a tension higher than a determined value, the resultant of the reaction force of the ball joint 10 on support 2, and in particular its component R in the orthogonal direction to the plane of points P1-P4, causes a controlled deformation (bending) of the means 15a and 15b (
The robotic wrist 1, as above described, can be mounted on a trocar 16 of known art, where tendons 8 extend and transmit the force F′, generated by a motor 40 and suitably deflected by connecting arms 7, to the robotic wrist of a device 20, which can carry out mininvasive surgical operations (
In figures from 9 to 12 four possible orientations are shown of robotic wrist 1 obtained acting onto tendons 8a-8d and then onto the respective connecting arms 7a-7d, following predetermined kinematic schemes.
In particular, tendons 8a-8d are subject to a tension, and changing each respective tension it is possible to cause the rotation of robotic wrist 1 in one of the three planes corresponding to the degrees of freedom of ball joint 10.
In figures from 13 to 16 the interface of connection 40 is shown of Tendons 8 to the respective motors 42. It provides a pulley 41 having a stem 43 directly fitted on the shaft of the respective motor 42. In particular, each pulley 41 is mounted on a bearing and is associated to a spring 44 to it co-axial suitable for pre-tensioning tendons 8. Sensors of position, for example encoders, can be mounted integral to the shafts of motors 42, with which it is possible to determine the position of the robotic wrist 10 and of connecting arms 7. In another preferred embodiment it is possible to provide a releasable connection between the shafts of the motors 42 and the stems 43 of the pulleys by means of clutches, for example. This way a device 20 is obtained for mininvasive surgical operations completely passive reducing the costs and reducing the sterilization problems.
In figures from 21 to 25 a diagrammatical kinematical view is shown of an alternative exemplary embodiment of the remotely actuated robotic wrist shown in figures from 1 to 20. As shown in
In
What above described represents the operation of an exemplary embodiment of the remotely actuated robotic wrist 101, whose practical implementation is shown as an alternative exemplary embodiment in
In particular, the rolling movement of sphere 161 on sphere 162 is split in two contributions in two respective orthogonal planes, using the mechanism described hereafter. More in detail, in the exemplary embodiment of
The independent forces F1 and F2 that are transmitted through each kinematical chain to support 102 are generated by respective remote motors, not shown, and are applied to the relative kinematical chain at points 151 and 157 respectively. This produces the motion of the kinematical chain with respect to fixed points 171 and 172 of device 101, which points belong, along with fixed pivot O2, to the fixed member of the device. In an exemplary embodiment of
In
The two exemplary embodiments of
Another practical embodiment of the mechanism of
The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
Number | Date | Country | Kind |
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P2003A000107 | Nov 2003 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB04/03731 | 11/15/2004 | WO | 00 | 6/6/2006 |