Patent Application
20170074376
Field of the Invention
Embodiments disclosed herein relate generally to manipulators and linear motion actuators that may be employed in a manipulator or elsewhere. In particular, the manipulator may be used in laparoscopic surgery.
Description of the Related Art
Manipulators of various types are used in laparoscopic surgery. In laparoscopic or minimally invasive surgery operations are performed through one or more small incision. There can be a number of advantages to the patient with laparoscopic surgery versus an open procedure. These can include reduced pain due to smaller incisions and hemorrhaging, and shorter recovery time. At the same time, laparoscopic surgery is limited in that the small incisions only allow relatively small devices into the body and once there, there is limited space within the body. Because of these limitations and many more considerations, there is a continual need for improvement in devices, such as manipulators, for use in laparoscopic surgery.
A linear motion actuator is disclosed. The linear motion actuator can include a double-shafted motor having a first motor shaft with a first screw thread and a second motor shaft with a second screw thread. The first screw thread can have certain characteristics that are different from that of the second screw thread. For example the pitch and/or lead of the first screw thread can be different from that of the second screw thread. In addition, the pitch of the first screw thread can be inverse to the pitch of the second screw thread. The linear motion actuator is disclosed for use in an arm assembly of a laparoscopic manipulator, but can also be used in other types of devices.
According to some embodiments, a linear motion actuator can include a double-shafted motor, and first and second shaft guides. The double-shafted motor can comprise a first motor shaft having a first screw thread and a second motor shaft having a second screw thread. A pitch of the first screw thread can be different from that of the second screw thread. The first shaft guide can have a threaded hole which engages with the first screw thread. The second shaft guide can have a threaded hole which engages with the second screw thread.
The linear motion actuator may further include a housing to accommodate the motor, the first shaft guide, and the second shaft guide. One or more of the first shaft guide, second shaft guide and motor can be secured to the motor housing. In some embodiments the first shaft guide is secured to the housing and the motor and second shaft guide are free to move with respect thereto. A linear guide can be incorporated within the housing to guide the motor and the second shaft guide in the housing, and prevent the housing and the second shaft guide from rotating relative to the first shaft guide.
In some embodiments, at least one of the first motor shaft and the second motor shaft can have two or more starts. In addition or instead, the pitch of the first screw thread can be inverted from that of the second screw thread. At least one of the screw threads can be a ball screw thread or other type of screw thread. Where a ball screw thread is used, the respective shaft guide has a ball assembly.
According to some embodiments, a manipulator can have a segmented arm with two or more arm assemblies pivotally connected to one another. At least one of the two or more arm assemblies can include a linear motion actuator, a housing, and a pivot mechanism. The linear motion actuator can be any of the iterations just described. For example, the linear motion actuator can include a double-shafted motor, and first and second shaft guides. The double-shafted motor can comprise a first motor shaft having a first screw thread and a second motor shaft having a second screw thread. A pitch of the first screw thread can be different from that of the second screw thread. The first shaft guide can have a threaded hole which engages with the first screw thread. The second shaft guide can have a threaded hole which engages with the second screw thread. The pivot mechanism can be used to pivot an adjacent arm assembly of the segmented arm. The pivot mechanism can comprise a member mounted on the second shaft guide of the linear motion actuator and extending toward the adjacent arm assembly. The first shaft guide can be secured to the tubular housing with the motor and second shaft guide being movable within the housing relative to the first guide shaft.
In some embodiments, the member of the pivot mechanism can comprise a push rod and the adjacent arm assembly can have a protrusion engaged with the push rod. Alternatively, the member of the pivot mechanism can be pinned to the second shaft guide at a first end and to the adjacent arm assembly at a second end. The pivot mechanism may include a spring to bias the adjacent arm assembly to a first position. The manipulator may also include an angular encoder.
According to some embodiments, the adjacent arm assembly has a distal end configured to couple to an end effector. The end effector can be actuated by a second linear motion actuator in the adjacent arm assembly. The end the end effector can be removably coupled to the distal end of the adjacent arm assembly. The adjacent arm assembly may further comprise a rotating member configured to support an organ. The rotating member can be actuated by the second linear motion actuator in the distal arm assembly through a rack-and-pinion so as to rotate about an axis orthogonal to a longitudinal axis of a housing of the adjacent arm assembly.
According to some embodiments, a manipulator can have a segmented arm with a distal arm assembly and a proximal arm assembly pivotally connected to the distal arm assembly. The distal arm assembly can have a distal end configured to couple to an end effector. The proximal arm assembly can include a linear motion actuator, a housing, and a pivot mechanism. The linear motion actuator can be any of the iterations just described. For example, the linear motion actuator can include a double-shafted reduction drive comprising first and second reduction drive shafts. The first reduction drive shaft can have a first screw thread and the second reduction drive shaft can have a second screw thread. Each of the first and second screw threads are threaded on first and second spindles, respectively. The linear motion actuator may further include a first reduction drive shaft guide having a threaded hole which engages with the first screw thread and a second reduction drive shaft guide having a threaded hole which engages with the second screw thread. The pivot mechanism can be configured to pivot the distal arm assembly. The pivot mechanism can comprise a member mounted on the second shaft guide of the linear motion actuator and extending toward the distal arm assembly. The first shaft guide can be secured to the housing, and the motor and the second shaft guide are movable within the housing relative to the first guide shaft.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. While the following detailed description is related to manipulators and linear motion actuators that may be employed in a manipulator, it is to be appreciated that the concepts described herein are also applicable to many other devices and methods.
A manipulator 100 can include an arm assembly 2 and an end effector 4. The end effector 4 can be any type of tool, for example in the surgery context, example end effectors can include, but are not limited to: probes, graspers, scissors, forceps, clip appliers, scalpels, electro cautery probes, and retractors. In other contexts, an end effector may include screwdrivers, suction, grabbers, hooks, etc. The manipulator may be stationary or moveable in position and can be positioned in such a way to allow use of the end effector 4 or other tool. The end effector 4 may be permanently or removably attached to the distal end of the manipulator.
In some embodiments, a manipulator 100 may include a segmented arm with two or more arm assemblies 2 connected to one another. The manipulator can be used to control the end effector 4, but also the relationship between the arm assemblies. For example, as will be described in more detail below, the two or more arm assemblies 2 can be connected pivotally, telescopically, etc. The illustrated embodiment of
The manipulator 100 can include any of a number of additional features. For example,
An actuation mechanism as part of the manipulator 100 can control one or more of the end effector(s) 4, other tool(s), and the relationship between arm assemblies 2. The manipulator 100 as illustrated has two linear motion actuators 200. A linear motion actuator 200 can provide linear motion which the manipulator can use for linear movement or the linear motion can be converted into another type of motion such as rotational movement, scissor movement, etc. The linear motion actuator 200 can include a motor 22 having one or more shafts 24A, 24B. The shaft(s) can have a screw thread engaging a shaft guide 28A, 28B that can cause linear movement with rotation of the shaft. In the illustrated embodiment, the linear movement can cause movement of the arm assemblies and/or movement of the forceps being used as an end effector 4.
It will be appreciated that a screw thread (or thread) is a helical structure often used to translate rotational motion to linear motion, known in some instances as a lead-screw or power screw. A screw thread is generally in the form of a ridge extending around a cylinder or cone in the form of a helix. The mechanical advantage of a screw thread can depend on various factors including the screw thread's lead (the linear distance the screw travels in one revolution) and the pitch (the distance from the crest of one thread to the next). It is possible to obtain a higher torque by reducing the thread pitch. However, the fine threading which results from the reduction of the pitch may not have adequate mechanical strength to exert the desired (high) torque. Materials capable of fine threading to exert high torque are also limited and can add to the already higher manufacturing cost associated with fine threading.
In the case where several gears are used for a small manipulator, the gear teeth must be made extremely small during manufacture, and even in the case of a usual helical channel or screw thread, the helical channel pitch must be made very small to obtain a large reduction ratio. Accordingly, mechanical strength becomes a significant issue and leads to limitations in the selection of materials. However, as shown above, it is not necessary to make the helical channel pitch very small in order to obtain a reduction ratio by means of the pitches of the two channels, thus increasing the number of viable materials.
Types of screw thread can include, but are not limited to, triangular thread, square thread, trapezoidal thread, or ball thread. When a ball thread is used, the first shaft guide 28A and second shaft guide 28B can further comprise a ball assembly. In addition, the screw thread can include a multi-start thread, such as a two, three or more start thread which can change the lead of the screw.
Turning now to
A linear motion actuator 200 can include a double-shafted motor 22 having a first motor shaft 24A with a first screw thread 26A and a second motor shaft 24B with a second screw thread 26B. A first shaft guide 28A can have a threaded hole 30A which engages with the first screw thread 24A and a second shaft guide 28B can have a threaded hole 30B which engages with the second screw thread 26B. One of the first shaft guide 28A, second shaft guide 28B, and motor 22 can be fixed in relation to the others so as to cause linear movement from rotation of the motor shafts.
In the illustrated example, the first shaft guide 28A is fixed in position with relation to both the second shaft guide 28B and the motor 22. Rotation of the motor shafts thereby causes one or both of the second shaft guide 28B and motor 22 to move away from or closer to the first shaft guide 28A. Though the screw threads can be the same, differences between them can be used to control the movement in a desired manner. For example, the pitch and/or lead of the first screw thread 26A can be different from that of the second screw thread 26B. In addition, the first screw thread 26A can be inverse to the second screw thread 26B (left-handed versus right-handed).
A net travel distance (or in this instance, increase in total length) (T2-T1) of the second shaft guide 28B with relation to the first shaft guide 28A can be obtained by calculating (L3-L1)-(L2-L4). The illustrated linear motion actuator 200 can beneficially provide a desired net travel distance of the second shaft guide 28B based on a number of rotations of the shafts. The respective pitch and/or lead of the first and second screw threads 26A, 26B can be set accordingly. For example, one can select a desired net travel distance of the second shaft guide 28B with respect to a number of rotations by selecting different pitches between the first screw thread 26A and the second screw thread 26B. In addition, the first screw thread 24A can be inverse to the second screw thread 24B. This can allow the linear motion actuator 200 to create an smaller overall linear movement without requiring fine threading. In addition, a large reduction ratio can be obtained, and it is possible to obtain a large torque with a small motor. If the screw threads are not inverse, than a larger overall linear movement can be made with finer threading and higher torque than a comparable single screw thread.
The conceptual diagram of
Returning to
In some embodiments, the double-shafted motor 22 can further include one or more spindles (not shown). The spindles can be coupled to the first motor shaft 24A and/or the second motor shaft 24B. In such embodiments, flexible couplers may be used to couple the spindles to the motor shafts so that the alignment between the double-shaft motor 22, and the shaft guides 28A, 28B need not be tight. Accordingly, it will be appreciated that the manufacturing cost can be reduced. Rigid couplers may also be used. In some embodiments, a spindle can include the motor shaft, bearings, and/or other element attached to the motor shaft, such as a clamp or a chuck. It will also be understood that the double-shafted motor 22, first motor shaft 24A and second motor shaft 24B can be made of a single continuous rod protruding from both ends of the motor.
A linear motion actuator 200 can further include a housing to accommodate the double-shafted motor. In the illustrated embodiments, such in
In some embodiments, the housing can further include a linear guide 34 to facilitate linear movement of the motor 22, first shaft guide 28A and/second shaft guide 28B. The linear guide 34 can comprise a groove (
As shown in
By employing the linear motion actuator in accordance with the non-limiting embodiments described above, a manipulator for a laparoscope or other device having improved performance can be achieved.
In some embodiments, the pivot mechanism 36 can include a linkage system, such as that shown in
In
Turning now to
In the illustrated linear motion actuator 200′, it can be seen that the double shaft 24 is not in the center of the arm assembly. It should be understood that all of the linear motion actuators 200, 200′ discussed herein can be centered or off-center within their respective housings.
Many of the conventional laparoscopic manipulators use one or more of a plurality of cables, a reduction drive, or a miniature motor to achieve controlled movement of the manipulator arms and/or end effectors.
In situations in which the target sites for laparoscopic procedures are performed on the reverse side of an internal organ, the manipulator arm(s) may need to re-position and/or support the weight of the internal organ—thereby facilitating access to the target site.
Another problem encountered with conventional laparoscopic manipulators 170 relates to the use of a miniature motor 72 (
One solution to the reduction ratio and “backlash” issues has been the use of a planetary reduction drive 70 as seen in
The manipulators and linear motion actuators as described herein provide many benefits and advantages over the conventional devices. For example, sufficient torque to drive the manipulator arm can be obtained even when using a small motor. The number of reduction gears can be reduced, and a high-precision manipulator can be realized. A large load can be supported with a simple structure as the disclosed linear motion actuator can naturally resist backdriving. Manufacturing costs can also be controlled because the number of components is substantially reduced and the need for high tolerances, such as with fine threading, is also reduced.
The helical shaft system of the linear motion actuator can provide a greater reduction ratio with fewer parts than the typical circular gear based systems. For example, this can be done by providing two helical channels which are inverted from one another and on the same axis. In addition, a difference in pitch between the helical channels can be used to provide greater control of the linear movement to be converted into radial or other types of movement to be used by a manipulator.
As detailed above, a small manipulator can be equipped with a high-torque running gear, allowing delicate operations. It can be used in laparoscopies and will contribute to the development of medical apparatuses with lower production costs. Two types of helical gear can be used to achieve large reduction ratio. Precise angle setting is possible. A large reduction ratio can be achieved with few precision parts. Large loads can be supported because of the few precision gears. In addition, if a larger reduction ratio is needed, a motor with a reduction gear can be used.
The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.
As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.
From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/36830 | 5/5/2014 | WO | 00 |
