WO2025015163A2

WO2025015163A2 - Systems and methods for flexible medical device articulation

Info

Publication number: WO2025015163A2
Application number: PCT/US2024/037602
Authority: WO
Inventors: Miles S. Joseph; Christopher M. Major; David Solum; Adam S. WIGGINTON
Original assignee: Intuitive Surgical Operations Inc
Current assignee: Intuitive Surgical Operations Inc
Priority date: 2023-07-13
Filing date: 2024-07-11
Publication date: 2025-01-16
Anticipated expiration: 2026-01-13
Also published as: WO2025015163A3

Abstract

A counter motion mechanism comprises a flexible elongate device that includes a first articulation section including a serial flexible links bendable along a translational direction and a second articulation section including serial flexible links bendable along the translational direction. A transition section extends between the first and second articulation sections. A control member extends between the first and second articulation sections and wraps approximately 180 degrees about a central axis at the transition section. The control member bends the first articulation section in a first direction as the second articulation section bends in a second direction opposite the first direction while a first link of the first articulation section and a second link of the second articulation section are maintained in parallel. A translational distance between the first and second links includes distances for the first and second articulation sections and the transition section.

Description

SYSTEMS AND METHODS FOR FLEXIBLE MEDICAL DEVICE ARTICULATION

CROSS-REFERENCED APPLICATIONS

[0001] This application claims priority to and benefit of U.S. Provisional Application No. 63/513,505 filed July 13. 2023 and entitled “Systems and Methods for Flexible Device Articulation.” which is incorporated by reference herein in its entirety.

FIELD

[0002] Examples described herein relate to systems and methods for flexible medical device articulation. More particularly, example systems and methods may include articulation mechanisms and flexible joints in articulation sections of a flexible medical device, such as counter motion mechanisms and/or layered linkages in a catheter.

BACKGROUND

[0003] Minimally invasive medical techniques may generally be intended to reduce the amount of tissue that is damaged during medical procedures, thereby reducing patient recovery time, discomfort, and harmful side effects. Such minimally invasive techniques may be performed through natural orifices in a patient anatomy or through one or more surgical incisions. Through these natural orifices or incisions an operator may insert minimally invasive medical instruments such as therapeutic instruments, diagnostic instruments, imaging instruments, and surgical instruments. Some minimally invasive medical instruments may be flexible and may include manipulatable articulation sections. Systems and methods that improve the function, precision, and reliability of articulation sections are needed.

SUMMARY

[0004] The following presents a simplified summary of various examples described herein and is not intended to identify key or critical elements or to delineate the scope of the claims.

[0005] In some examples, a counter motion mechanism comprises a flexible elongate device that includes a first articulation section including a serial flexible links bendable along a translational direction and a second articulation section including serial flexible links bendable along the translational direction. A transition section extends between the first and second articulation sections. A control member extends between the first and second articulation sections and wraps approximately 180 degrees about a central axis at the transition section. The control member bends the first articulation section in a first direction as the second articulation section bends in a second direction opposite the first direction while a first link of the first articulation section and a second link of the second articulation section are maintained in parallel. A translational distance between the first and second links includes distances for the first and second articulation sections and the transition section.

[0006] In some examples, a counter motion mechanism comprises a flexible elongate device extending along a central axis. The flexible elongate device comprises a first articulation section including a first link, a second articulation section including a second link, and a transition section extending between the first and second articulation sections. A control member extends from a region proximal to the first articulation section to the second articulation section and wraps approximately 180 degrees about a central axis at the transition section. The control member is configured to bend the first articulation section in a first direction and the second articulation section in a second direction opposite the first direction while the control member maintains the first link and the second link in a parallel orientation. The control member maintains the parallel orientation without use of separate tension elements extending strictly between the first articulation section and the second articulation section to maintain the parallel orientation.

[0007] In some examples, a flexible elongate instrument assembly comprises a joint section including a first link movably coupled to a second link. The first link includes a first inner link member and a first outer link member surrounding the first inner link member, and the second link including a second inner link member and a second outer link member surrounding the second inner link member. The first inner link member and the second inner link member are movably engaged to form an inner link assembly. The first outer link member and the second outer link member are movably engaged to form an outer link assembly. The inner link assembly is coupled to the outer link assembly to resist axial displacement between the inner and outer link assemblies.

[0008] It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory in nature and are intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure. In that regard, additional aspects, features, and advantages of the present disclosure will be apparent to one skilled in the art from the following detailed description.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0009] FIG. 1 is a simplified diagram of a patient anatomy, according to some examples.

[0010] FIG. 2A is a side view of a medical instrument system, according to some examples. [0011] FIG. 2B is a side view of the medical instrument system of FIG. 2A in an articulated configuration.

[0012] FIG. 3A is a side view of a medical instrument system, according to some examples.

[0013] FIG. 3B is a side view of the medical instrument system of FIG. 3 A in an articulated configuration.

[0014] FIGS. 4A and 4B are cross sectional views of the medical instrument system of FIG. 3A.

[0015] FIG. 5A is a side view of a medical instrument system, according to some examples.

[0016] FIG. 5B is a side view of the medical instrument system of FIG. 5 A in an articulated configuration.

[0017] FIG. 6 is a side view of a medical instrument system, according to some examples.

[0018] FIG. 7 is a side view of a medical instrument system, according to some examples.

[0019] FIG. 8A is a side view of a medical instrument system, according to some examples.

[0020] FIG. 8B is a side view of the medical instrument system of FIG. 8A in an articulated configuration.

[0021] FIG. 9A illustrates a plurality of control members and function cables in an example arrangement, according to some examples.

[0022] FIG. 9B illustrates a plurality of control members and function cables in an example arrangement, according to some examples.

[0023] FIGS. 10A-10F illustrate in a joint section including inner and outer joint assemblies, according to some examples.

[0024] FIGS. 11 and 12 illustrate cross-sectional views of inner and outer link members with retaining systems between the inner and outer link members, according to some examples.

[0025] FIG. 13 illustrates an articulation section bendable in a single plane, according to some examples.

[0026] FIG. 14 illustrates an articulation section bendable in two planes, according to some examples. [0027] FIG. 15 illustrates a medical instrument system including an articulation section independently articulatable relative to articulatable wrist mechanism, according to some examples.

[0028] FIG. 16 illustrates a non-antagonistic control member configuration, according to some examples.

[0029] FIG. 17 illustrates a cross-sectional view of inner and outer link members with a retaining system, according to some examples.

[0030] FIG. 18A illustrates a sectional view of an articulation section, according to some examples.

[0031] FIG. 18B illustrates a cross-sectional view of inner and outer link members of FIG. 18 A.

[0032] FIG. 19A illustrates a sectional view of an articulation section, according to some examples.

[0033] FIG. 19B illustrates a cross-sectional view of inner and outer link members of FIG. 19 A.

[0034] FIG. 20 is a partially transparent view of an articulation section with a serpentine flexure joint, according to some examples.

[0035] FIG. 21 is a partially transparent view of an articulation section with a serpentine flexure joint, according to some examples.

[0036] FIG. 22 illustrates a joint section with a serpentine flexure joint and an involute joint, according to some examples.

[0037] FIG. 23A illustrates a side view of an articulation section, according to some examples.

[0038] FIG. 23B illustrates a cross-sectional view of the articulation section of FIG. 23 A.

[0039] FIG. 24 is a robotically-assisted medical system, according to some examples.

[0040] FIG. 25A is a simplified diagram of a medical instrument system according to some embodiments.

[0041] FIG. 25B is a simplified diagram of a medical instrument system with an extended medical instrument according to some embodiments.

[0042] Examples of the present disclosure and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures, wherein showings therein are for purposes of illustrating examples of the present disclosure and not for purposes of limiting the same. DETAILED DESCRIPTION

[0043] The technology described herein relates to flexible instrument systems which may include a flexible device, such as a catheter or endoscope, through which one or more flexible instruments may be extended. Various systems and methods are described providing articulation mechanisms and/or flexible joints in articulation sections of flexible instrument systems, including counter motion mechanisms and/or linkage mechanisms used to precisely control articulations. Although the examples provided herein may be used for procedures within the gastrointestinal system, it is understood that the described technology may be used in performing procedures in artificially created lumens or any endoluminal passageway or cavity, including in a patient trachea, colon, intestines, stomach, liver, kidneys and kidney calices, brain, heart, lungs, circulatory system including vasculature, fistulas, and/or the like. In some examples, flexible instrument systems may include a counter motion mechanism with a control member that wraps, jogs, or spirals approximately 180 degrees about a central axis between proximal and distal articulation sections. In some examples, flexible instrument systems may include articulation joints with linkages that include a rolling interface that allows the joint section to tolerate increased axial load and an involute interface that enforces the rolling interface by constraining the corresponding rolling interface to prevent sliding between the rolling interface surfaces.

[0044] FIG. 1 illustrates a medical instrument system 100 extending within anatomic passageways 102 of an anatomical structure 104. In some examples the anatomic structure 104 may be a stomach. The anatomic structure 104 has an anatomical frame of reference (XA, YA, ZA). A distal end portion 106 of the medical instrument system 100 may be advanced into an anatomic opening (e.g., a patient mouth) and through the anatomic passageways 102 to perform a medical procedure at or near target tissue located in a region 108 of the anatomic structure 104 using any of the methods or systems described herein. The medical instrument system 100 may include any of various tools, instruments, or end effectors. For example, the medical instrument system 100 may include a biopsy or tissue sampling tool (e.g., needle or forceps), a suturing tool, an ablation tool, an imaging tool, grasping instrument, cutting instrument, gripping instrument, a medication elivery device, and/or another type of surgical, diagnostic, or therapeutic device.

[0045] In some examples, a medical system may include a counter motion mechanism (which also may be referred to as a parallel motion mechanism) that allows a position of a reference frame at a distal end portion of the mechanism to be changed with respect to a position of a reference frame at a proximal end portion of the mechanism, without changing an orientation of the distal reference frame. FIG. 2A provides a schematic view of a distal portion of a medical instrument system 200 (e.g., the medical instrument system 100) which may include a proximal body 201, counter motion mechanism 202, a wrist mechanism 204, and an end effector 206. In some embodiments, the wrist mechanism 204 may be omitted. The counter motion mechanism 202 includes link body 207 extending between a first joint 208 (e.g., a proximal joint) that couples to the proximal body 201 and between a second joint 210 (e.g., a distal joint) that couples to the wrist mechanism 204 or end effector 206 in examples that omit the wrist mechanism 204. In some examples, the link body 207 may include a single rigid tubular member that may, for example, have a length of approximately 2-3 cm. The first joint 208 includes a proximal link 208a and a distal link 208b, and the second joint 210 includes a proximal link 210a and a distal link 210b. In an unarticulated configuration as shown in FIG. 2A. an axis Al extending through the proximal body 201 and the link 208a may be generally collinear with an axis Bl extending through the link 210b and wrist 204. In this configuration, a flexible longitudinal axis LI is aligned with the axes Al, Bl.

[0046] A set of tension elements 220a, 220b are positioned on opposite sides of the counter motion mechanism 202 and couple the proximal link 208a in the first joint 208 to the distal link 210b in the second joint 210. A set of control cables 222a. 222b are coupled to the distal link 208b of the first joint 208 and extend proximally through proximal body 201 to a transmission mechanism (e.g., drive unit 1004). A set of function cables 224a, 224b couple to the w rist mechanism 204 and/or the end effector 206 and extend proximally to the transmission mechanism to control the operation of the wrist mechanism 204 and/or the end effector 206. The tension elements, control cables, and function cables may include any type of elongated actuation member including tendons, wires, Bowden cables, hypotubes, or any other structures that are able to transfer force from steering transmission mechanism.

[0047] As shown in FIG. 2B, when the transmission mechanism applies a tensile force on control cable 222a (control cable 222b is allowed to pay out), first joint 208 bends in a first direction. The tension elements 220a. 220b coupling between the proximal link 208a of the first joint 208 and the distal link 210b of the second joint 210 causes second joint 210 to bend an equal amount in a second direction opposite to the first direction. Consequently, wrist 204 and end effector 206 are laterally displaced away from axis Al of proximal body segment 201, but the orientation of wrist 204 and end effector 206 remain unaffected (i.e.. axis Bl remains substantially parallel to the axis Al). Further details are disclosed in U.S. Pat. No. 7,942,868, which is incorporated by reference herein in its entirety. Since the joints 208 and 210 are coupled together via the constraint and control cables, they do not operate independently of one another. Therefore, in joint space the entire counter motion mechanism 202 may be considered a single joint with one degree of freedom (i.e., pitch or yaw) if joints 208, 210 each have a single bending degree of freedom. Thus, the position of the distal end of the mechanism may change only in 2D Cartesian space. In this example, a lateral displacement DI extends between the link 208a and the link 210b (and the axes Al. Bl) in a direction generally perpendicular to the axes Al, Bl. The lateral displacement DI results from the rigid link body 207 and the tension elements 220a, 220b that restrict motion of the link 210b relative to link 208a. In alternative embodiments, the joints may have two orthogonal bends and accordingly, two degrees of freedom (i.e.. pitch and yaw) so that the position of the distal end of the mechanism may change in 3D Cartesian space. The counter motion mechanism’s motion may be considered “parallel motion” because the relative orientations of the proximal and distal end portions (frames) of the mechanism remain constant as the mechanism changes the distal end portion's (frame's) position.

[0048] For some medical procedures, a counter motion mechanism may be comprised of a plurality of links that provide greater flexibility’ while achieving the same parallel motion. In the more flexible examples (e.g., FIGS. 3A, 3B, 4A, 4B), the rigid link body of the counter motion mechanism may have a reduced length compared to the rigid link body 207 of FIGs. 2A/2B or may be eliminated entirety in favor of a series of flexible links. Further, the tension elements that constrain the motion of the counter motion mechanism may be omitted in the more flexible examples. FIG. 3A provides a schematic view of a distal portion of a medical instrument system 300 which includes a flexible counter motion mechanism 302, a proximal body 301, a wrist mechanism 304, and an end effector 306. In some embodiments, the wrist mechanism 304 may be omitted. The counter motion mechanism 302 includes a flexible elongate device comprising a transition section 307 extending between a proximal articulation section 330 that couples to the proximal body 301 and between a distal articulation section 332 that couples to the wrist mechanism 304 or end effector 306 in examples that omit the wrist mechanism 304. The proximal articulation section 330 includes a proximal link 308 and a series of links 309 coupled between the proximal link 308 and the transition section 307. The distal articulation section 332 includes a distal link 310 and a series of links 311 coupled between the distal link 310 and the transition section 307. In an unarticulated configuration as shown in FIG. 3A. an axis A2 through the link 308 may be generally collinear with an axis Bl through the link 310. In this configuration a flexible central longitudinal axis L2 is aligned with the axes A2, B2. The series of links 309 and 311 may be coupled by articulating joints including, for example, flexure joints, hinge or pivoting joints, and/or rolling joints. In some examples, the transition section 307 may include a single rigid tubular member that may be shorter than the link body 207 of FIGS. 2A/2B, such that a full lateral displacement D2 does not result entirely from the length and angle of the transition section 307, and instead lateral displacement includes articulation of at least portions of the proximal articulation section 330 and/or the distal articulation section 332. For example, the transition section 307 may have a length of approximately 1 cm compared to the length of 2-3 cm for the link body 207 of FIGS. 2A/2B. In other examples, the transition section may omit a rigid tubular member and instead may include a continuous series of links, as described in FIGS. 5 A and 5B below. A minimized or omitted rigid tube length at the transition section may allow the medical instrument system 300 to navigate tortuous anatomic passageways that may be impassable by a longer rigid tube. For example, a transition section with a rigid tube having a minimized length or with a series of links of a length similar to links 309 may allow for greater flexibility' of the medical instrument as it navigates the anatomy.

[0049] In some examples, the proximal articulation section 330, the distal articulation section 332, and the transition section 307 may be cut (e.g., laser cut) from a continuous thinwalled tube, such as a nitinol hypotube. In some examples, struts or other structural members may be retained between the links as the tube is cut. At a later stage of the manufacturing process or before the medical instrument is deployed, the struts or structural members may then be removed to allow for bending at the joints.

[0050] A set of function cables 324a, 324b couple to the wrist mechanism 304 and/or the end effector 306 and extend proximally to the transmission mechanism to control the operation of the wrist mechanism 304 and/or the end effector 306. A control member 334 is coupled to the distal link 310 of the distal articulation section 332 and extends proximally along the links 311 along a first lateral side 340 of the counter motion mechanism 302, as shown in the cross- sectional view of FIG. 4A. At the transition section 307, the control member 334 wraps or jogs approximately 180 degrees around the axis L2 to extend proximally along the links 309 along a second lateral side 342 of the counter motion mechanism 302 to the link 308, as shown in the cross-sectional view of FIG. 4B. A central axis of the control member 334 further extends proximally through the proximal body 301 to a transmission mechanism (e.g., drive unit 1004). The control member 334 may extend a distance R1 from the longitudinal axis L2. The transition section 307 may resolve or support the load generated by the control member 334 to prevent motion outside of the expected articulation. The function cables and control member may be any type of elongated actuation member including a tendon, wire, Bowden cable, hypotube, or any other structures that are able to transfer force from steering transmission mechanism.

[0051] As shown in FIG. 3B, when the transmission mechanism applies a tensile force on control member 334, the proximal articulation section 330 bends in a first direction Fl and the distal articulation section 332 bends in an approximately equal amount in an opposite second direction F2. The bending of the proximal articulation section 330 and the distal articulation section 332 may be constrained to the same plane (e.g., in a yaw plane or a pitch plane). Consequently, wrist 304 and end effector 306 are laterally displaced away from axis A2 of link 308, but the orientation of wrist 304 and end effector 306 remain unaffected (i.e., axis B2 remains parallel to the axis A2). Since the proximal articulation section 330 is coupled to the distal articulation section 332 and motion is controlled by the control member 334, the articulation sections do not operate independently of one another. In this example, a lateral displacement D2 extends between the link 308 and the link 310 (and the axes A2, B2) in a direction generally perpendicular to the axes A2, B2. The full lateral displacement D2 includes a translation displacement T 1 through the transition section 307 and a translation displacement T2 through each of the articulation sections 330 and 332. Thus, the full lateral displacement D2 of the links 308, 310 is a total of the translation displacements (T1 + 2xT2) of the articulation sections 330, 332 and the transition section 307 that result from the 180 degree wrap of the control cable. The translational displacements Tl, T2 may be in a common direction, generally perpendicular to the axes A2, B2. In various embodiments, the relative amount of translation displacement T2 for each of the articulation sections 330, 332 may be the same or different from each other (e.g., displacement for the articulation section 330 may be greater than, equal to, or less than the articulation section 332). In some embodiments, the total translation displacement T2 may be entirely via articulation section 330 or entirely via articulation section 332.

[0052] As compared to the counter motion mechanism example of FIGS. 2A/2B, in which approximately all of the lateral displacement DI may be due to the length and angle of the rigid link body 207. the lateral displacement D2 may be a result of the length and angle of the transition section 307 as well as the bends in the articulation sections 330, 332. Further as compared to the counter motion mechanism example of FIGS. 2A/2B, the control member 334 wrapped approximately 180 degrees provides the bending constraint, so that tension elements that extend through the rigid body may be omitted. In alternative examples, the articulation sections may have orthogonally pivoting joint pairs and accordingly, two degrees of freedom (i.e., pitch and yaw- planes) so that the position of the distal end of the mechanism may change in 3D Cartesian space. The counter motion mechanism’s motion may be considered “parallel motion” because the relative orientations of the proximal and distal ends (frames) of the mechanism remain constant as the mechanism changes the distal end's (frame's) position.

[0053] FIGS. 5A and 5B provide a schematic view of a distal portion of a medical instrument system 400 which includes a flexible counter motion mechanism 402 with a continuous series of links. The medical instrument system also includes a proximal body 401, a wrist mechanism 404, and an end effector 406. In some embodiments, the wrist mechanism 404 may be omitted. The counter motion mechanism 402 includes a flexible elongate device comprising a proximal articulation section 430 that couples to the proximal body 401 and a distal articulation section 432 that couples to the wrist mechanism 404 or end effector 406 in examples that omit the wrist mechanism 404. The proximal articulation section 430 includes a proximal link 408 and a series of links 409. The distal articulation section 432 includes a distal link 410 and a series of links 411. A transition section 407 includes links from the proximal articulation section 430 and the distal articulation section 432. In an unarticulated configuration as shown in FIG. 5A, an axis A3 through the link 408 may be generally collinear with an axis B3 through the link 410. In this configuration, a flexible longitudinal axis L3 is aligned with the axes A3, B3. The series of links 409 and 411 may be coupled by articulating joints including, for example, flexure j oints, hinge or pivoting joints, and/or rolling joints. In this example, the transition section may omit a rigid tubular member, allowing the medical instrument system 400 to navigate tortuous anatomic passageways that may be impassable by a longer rigid tube.

[0054] A set of function cables 424a, 424b couple to the wrist mechanism 404 and/or the end effector 406 and extend proximally to the transmission mechanism to control the operation of the wrist mechanism 404 and/or the end effector 406. A control member (e.g.. cable, pull wire) 434 is coupled to the distal link 410 of the distal articulation section 432 and extends proximally along the links 411 along a first lateral side 440 of the counter motion mechanism 402. At the transition section 407, the control member 434 wraps approximately 180 degrees around the axes A3, B3 to extend proximally along the links 409 along a second lateral side 442 of the counter motion mechanism 402 to the link 408. The control member 434 further extends proximally through the proximal body 401 to a transmission mechanism (drive unit 1004). Similarly to the control member 334, the control member 434 may be coupled to the links 409, 411 at approximately the distance from the central longitudinal axis L3, but on opposite sides (432, 340. respectively) of the central longitudinal axis L3. The transition section 407 may resolve or support the load generated by the control member 434 to prevent motion outside of the expected articulation.

[0055] As shown in FIG. 5B, when the transmission mechanism applies an actuating force, such as a tensile force, on control member 434, the proximal articulation section 430 bends in a first direction Fl and the distal articulation section 432 bends in an approximately equal amount in an opposite second direction F2. The bending of the proximal articulation section 430 and the distal articulation section 432 may be constrained to the same plane (e.g.. in a yaw plane or a pitch plane). Consequently, wrist 404 and end effector 406 are laterally displaced away from axis A3 of link 408, but the orientation of wrist 404 and end effector 406 remain unaffected (i.e., axis B3 remains parallel to the axis A3). Since the proximal articulation section 430 is coupled to the distal articulation section 432 and motion is controlled by the control member 434, the articulation sections do not operate independently of one another. In this example, a lateral displacement D3 extends between the link 408 and the link 410 (and the axes A3. B3) in a direction generally perpendicular to the axes A2, B2. The full lateral displacement D3 includes a translation displacement T3 through the transition section 407 and a translation displacement T4 through each of the articulation sections 430 and 432. Thus, the full lateral displacement D3 of the links 408, 410 is a total of the translation displacements (T3 + 2xT4) of the articulation sections 430, 432 and the transition section 407 that result from the 180 degree wrap of the control cable. The translational displacements T3, T4 may be in a common direction, generally perpendicular to the axes A3, B3. In various embodiments, the relative amount of translation displacement T4 for each of the articulation sections 430, 432 may be the same or different from each other (e.g., displacement for the articulation section 430 may be greater than, equal to, or less than the articulation section 432). In some embodiments, the total translation displacement T4 may be entirely via articulation section 430 or entirely via articulation section 432.

[0056] As compared to the counter motion mechanism example of FIGS. 2A/2B, in which approximately all of the lateral displacement DI may be due to the length and angle of the rigid link body 207. the lateral displacement D2 may be a result of the bends in the articulation sections 430. 432. Further as compared to the counter motion mechanism example of FIGS. 2A/2B, the control member 434 wrapped approximately 180 degrees provides the bending constraint, so that tension elements may be omitted. In alternative examples, the articulation sections may have orthogonally pivoting joint pairs and accordingly, two degrees of freedom (i.e., pitch and yaw planes) so that the position of the distal end of the mechanism may change in 3D Cartesian space. The counter motion mechanism’s motion may be considered “parallel motion” because the relative orientations of the proximal and distal ends (frames) of the mechanism remain constant as the mechanism changes the distal end's (frame’s) position.

[0057] FIG. 6 illustrates a side view of a medical instrument system 500 that may be substantially similar to medical instrument system 300, with differences as described. In this example, a counter motion mechanism 502 includes the flexible elongate device comprising a transition section 307 extending between the proximal articulation section 330 and the distal articulation section 332. A flexible central longitudinal axis L4 extends through the counter motion mechanism. A control member 534 may be coupled to interior surfaces of the links 309 of the proximal articulation section 330 by one or more flexible guide tubes 536, to interior surfaces of the links 311 of the distal articulation section 332 by one or more flexible guide tubes 538, and to interior surfaces of the transition section 307 by one or more flexible guide tubes 540. In the proximal articulation section 330, the flexible guide tubes 536 may extend along the lateral side 342 of the counter motion mechanism 502. In the distal articulation section 332, the flexible guide tubes 538 may extend along the lateral side 340 of the counter motion mechanism 502, at an approximately 180 degree offset from the flexible guide tubes 536. In an unarticulated configuration, the flexible guide tubes 536, 538 may extend generally linearly along the interior wall of a single link 309, 311 or across the interior of a joint formed by consecutive links 309 or consecutive links 311. At the transition section 307, the one or more flexible guide tubes 540 may be arranged to wrap approximately 180 degrees around the axis L4. In some examples, the flexible guide tubes may be flexible sections of elastomeric or metal tubing. In some examples, the flexible guide tubes may include coil pipes or springs that are welded or adhesively coupled to the links or transition section. At the articulation sections 330, 332, the flexible guide tubes may allow the articulation sections to bend. In examples (e.g., FIGS. 5A/5B) in which the transition section includes a plurality of serial links, the flexible guide tubes may be coupled to interior walls of the transition section links and may permit at least limited bending in the transition section. In some examples, the flexible guide tube (e.g., springs) may be welded to adjacent links and may serve as both a flexure joint and a conduit to route the control member.

[0058] The control member 534 may be fixed directly to the link 310 or may be fixed to the flexible guide tube 538 that is fixed to the link 310. In some examples the control member 534 may be welded, soldered, brazed, or crimped to the link 310. The control member 534 may extend through the guide tubes 538 of the articulation section 332 along the side 340 of the counter motion mechanism 502. At the transition section 307. the control member 534 may extend through the flexible guide tubes 540, causing the control member 534 to wrap approximately 180 degrees about the central axis L4. The control member 534 may further extend through the guide tubes 536 of the articulation section 330 along the side 342 of the counter motion mechanism 502. Thus, the flexible guide tubes 536, 540, 538 may maintain a predetermined radial orientation of the control member 534 about the axis L4, while also allowing the articulation sections 330, 332 to bend, as previously described for FIG. 3B, when an actuation force, such as a tension, is applied to the control member 534.

[0059] FIG. 7 illustrates a side view of a medical instrument system 600 that may be substantially similar to medical instrument system 300, with differences as described. In this example, a counter motion mechanism 602 includes three control members 634, 636, 638 extending through the counter motion mechanism 602 along paths spaced radially approximately 120 degrees. A flexible central longitudinal axis L5 extends through the counter motion mechanism. Flexible guide tubes 610, 612, 614 may be coupled to interior surfaces of the links 309 of the proximal articulation section 330 and may be spaced approximately 120 degrees apart about the axis L5. Flexible guide tubes 616, 618, 620 may be coupled to interior surfaces of the links 311 of the distal articulation section 332 and may be spaced approximately 120 degrees apart about the axis L5. Flexible guide tubes 622, 624, 626 may be coupled to interior surfaces of the transition section 307 and may be spaced approximately 120 degrees apart about the axis L5. At the transition section 307, the flexible guide tubes 622, 624, 626 may also be arranged to wrap approximately 180 degrees around the axis L5. The flexible control members of the medical instrument system 600 may be substantially similar in structure and attachment as the flexible control members of the medical instrument system 300. The control member 634 may extend through the flexible guide tubes 616, 622, 610. The control member 636 may extend through the flexible guide tubes 618, 624, 612. The control member 638 may extend through the flexible guide tubes 620, 626, 614. The three control members may be independently tensioned, allowing each articulation section to bend in three planes. The three-dimensional bend of the proximal articulation section 330 is of approximately the same magnitude but in the opposite direction as the three-dimensional bend of the distal articulation section 332. In alternative examples two control members or four or more control members may be used to provide other options for freedom of motion of the counter motion mechanism. [0060] FIG. 8 A illustrates a side view of a medical instrument system 700 that may be substantially similar to the medical instrument 600, with differences as described. As show n in this example, function cables 324a, 324b, 324c are spaced radially approximately 120 degrees apart and extend through the links of the counter motion mechanism 602 to couple at a wrist mechanism 702. The function cables 324a, 324b, 324c may be coupled to the links of the wrist mechanism 702 by flexible guide tubes 704. As shown in FIG. 8B. the control members 634, 636, 638 may be tensioned to bend the counter motion mechanism 602 as previously described, and the function cables 324a, 324b, 324c may be tensioned independently of the control members to cause three-dimensional motion of the wrist mechanism 702 while the counter motion mechanism 602 remains held in a fixed configuration.

[0061] In the example of FIGS. 8A and 8B, at a transition section 706, the function cables 324a. 324b, 324c may extend through a passage bounded by the control members 634. 636. 638. In other words, the control members are wrapped, at least partially, over or around the function cables. In this example, because the function cables are relatively close to the central axis, the coil pipes of the function cables may experience less sliding than if they w ere spaced farther from the central axis. The diameter of the function cables may be limited by the boundary' of the control members and the overall diameter of the medical instrument. The examples of FIGS. 9A and 9B provides alternative examples for arranging the function cables with respect to the control members. In FIG. 9A, function cables 324d extend axially outside the wrapped control members 634, 636, 638. In this example, the control members may be wrapped closer to the central axis (thus potentially requiring less length of control member material), creating a smaller through passage, since the passage does not need to accommodate passage of the function cables. In FIG. 9B, function cables 324e are arranged next to or interleaved with the control members 634, 636, 638 and wrap or spiral at the transition section. In this example, the function cables may have a larger diameter, as compared to the other examples, while maintaining the same size outer diameter of the medical instrument.

[0062] As described in the examples above, articulation sections, transition sections and wrist mechanisms of the medical instrument systems may include series of connected links. A pair of connected links may be referred to as a joint section. When a control member of the medical instrument is actuated (e.g., tensioned), the joint section may experience compressive and moment loads. The moment load may result in the desired angular deflection, but the compressive load may be resolved longitudinally, resulting in undesirable compression of the joint sections. High axial stiffness may be preferred for articulated medical instruments to prevent shortening or compression of the flexible links and joint sections under compressive loads, thus allowing more of the tensile force to be applied to articulating the joint section, rather than compressing the joint sections. Reducing or preventing axial shortening may make the medical instrument system more responsive to robotcally-assisted control, may allow for more repeatable and predictable control, and may cause the joint section to be more durable. [0063] Various types of joint sections may be used in medical instrument systems. Flexure joints, for example, include a bending member or strut that connects two links. The physical connection of the links may prevent joint separation, and long series of links may be cut from a single thin-walled tube. Flexure joints may, in some cases, be prone to buckling or fatigue failures. Hinge or pivot joints may include two links connected by a hinge (e.g., rivets, dovetailed cups, ball and socket) that prevent or resist separation. Hinge j oints may be durable than flexure joints but sliding friction may occur at the interfacing hinge surfaces. Hinge joints may also pinch or trap nearby materials such jackets, braids, or inner members like cables and sensors. Rolling joints may include two links that rotate and translate with respect to each other with minimal or no sliding friction between the links. Rolling joints may be more durable than flexure joints since there is no stmt under repeated bending. A rolling joint may be able to resolve much higher loads than flexure and hinge joints. With rolling joints, as the joint articulates, the neutral axis may move closer to the inside of the bend which may reduce the moment arm between the actuation member (e.g., cable) and the rolling contact point.

[0064] Small diameter thin-walled flexible devices such as catheters and endoscopes through which one or more flexible instruments may be extended may use flexure joints or hinge joints because they may be made from thin-walled, laser cut tubes, and axial forces for those applications may be relatively low. Rolling joints may be used in other types of instruments, such as laparoscopic instruments, where axial forces (e.g.. tensile forces) may be higher and the load bearing surface and rolling constraint may be machined or injection molded. Still other types of instruments, such as flexible endo-surgery instruments, need to be small, thin-walled, and flexible but also withstand high axial forces to manipulate tissue, including pulling, pushing, and cutting tissue. Flexure joints may experience buckling and fatigue failures under high axial forces, and hinge joints may experience large amounts of friction under high axial forces. In the examples provided below, joint sections may include rolling joints that may be used, for example, with flexible endo-surgery instruments that apply high axial forces, and may additionally be used for flexible devices such as catheters and endoscopes.

[0065] FIGS. 10A-10F illustrate ajoint section 800 in various unarticulated and articulated configurations. The joint section 800 may be used alone or in series, for example in the articulation section 330 or the transition section 407. FIGS. 10A, 10C, and 10E illustrate outer views of the joint section 800, and FIGS. 10B, 10D, and 10F illustrate cross-sectional views of the joint section 800. The joint section 800 may include a first link 802 in contact with a second link 804. The link 802 may include an inner link member 806 and an outer link member 808 surrounding the inner link member 806. The link 804 may include an inner link member 810 and an outer link member 812 surrounding the inner link member 810. The inner link members 806, 810 may form an inner link layer or assembly 814, and the outer link members 808, 812 may form an outer link layer or assembly 816. The inner link assembly 814 may be coupled to and extend within the outer link assembly 816. In an unarticulated configuration, as shown in FIGS. 10A and 10B, the joint section 800 may be aligned along a central longitudinal axis Cl. In a bent configuration, as shown in FIGS. 10C and 10D. the joint section 800 may be bent in a direction Gl. In a bent configuration, as shown in FIGS. 10E and 10F, the joint section 800 may be bent in a direction G2.

[0066] The links 808, 812 of the outer link assembly 816 may be coupled by an involute interface coupling which includes a projection or tooth 820 of the outer link member 808 engaged with a recess 822 betw een involute surfaces or teeth of the outer link member 812. The projection 820 and the recess 822 may have involute curved surfaces that contact each other and permit rolling involute motion when the joint section 800 is bent in the direction Gl or G2. The links 806, 810 of the inner link assembly 814 may include curved projections 824, 826, respectively, that may interface in a rolling motion when the joint section 800 is bent in the direction Gl or G2. The inner and outer links members 806, 808 of link 802 may be fixedly attached to each other by retaining members 828, and the inner and outer link members 810, 812 of link 804 may be fixedly attached to each other by retaining member 830. The inner and outer link members may additionally or alternatively be coupled by laser welding or other adhesion techniques or materials. When the actuation of an actuation member (e.g., tension on a control member) causes the joint section 800 to bend in the direction Gl or G2, the inner link assembly 814, with the rolling contact surfaces, may accommodate high axial or compressive loads placed on the joint section while the outer link layer 816, with the involute contact surfaces, may constrain the rolling contact of the inner link assembly 814 and prevent the projections 824, 826 from sliding relative to each other.

[0067] In alternative examples, the outer link assembly may include the rolling surface contact links and the inner link assembly may include the involute contact links. Including the involute contact links in the outer layer, however, may provide a visual confirmation during assembly, repair, or other inspection to confirm that the involute teeth surfaces are interlocked. [0068] FIGS. 11 and 12 illustrate cross-sectional views of link members 840, 842 with retaining members (e.g., retaining members 828, 830) which, in this example, may capture and provide a motion restraint to control cables, function cables, tension elements, or other flexible elements extending through the joint section. In some examples, the retaining members may also provide a mechanical coupling between the inner link members to the outer link members as an addition or alternative to other fixation techniques such as laser welding. As shown in the example of FIG. 11 , an outer link member 840 may couple to an inner link member 842 with a retaining member 844. In this example, the retaining member 844 may include a projection formed by distended or stamped portion of a wall of the outer link member 840 that extends into an opening or aperture 846 in a wall of the inner link member 842. The retaining member 844 may have a passage 843 through which control cables, function cables, tension elements, or other elongate elements may extend. In this example, the outer link member 840 is coupled to the inner link member 842 by four retaining members, but more or few er retaining members may be used to keep the inner link member 842 fixed with respect to the outer link member 840. As shown in the example of FIG. 12, an outer link member 850 may couple to an inner link member 852 with a retaining member 854 which, in this example, may capture and provide a motion restraint to control cables, function cables, tension elements, or other flexible elements extending through the joint section. In some examples, the retaining members may also provide a mechanical coupling between the inner link members to the outer link members as an addition or alternative to other fixation techniques such as laser welding. In this example, the retaining member 854 may include a compressible, snap-in eyelet with a compressible section 855 that may be compressed to extend into an opening or aperture 856 in a wall of the inner link member 852. When compressible section 855 returns to an expanded state (e.g., a partial uncompressed state or fully uncompressed state) inside the wall of the inner link member 852, the compressible section 855 retains the outer link member 850 to the inner link member 852. The retaining member 854 may have a passage 853 through which control cables, function cables, tension elements, or other elongate elements may extend. In this example the outer link member 850 is coupled to the inner link member 852 by four retaining members, but more or fewer retaining members may be used to keep the inner link member 852 fixed with respect to the outer link member 850. In some examples, a combination of the retaining members 842, 852 may be used to couple outer and inner link members.

[0069] FIG. 13 illustrates an articulation section 860 (e.g., 330) that may include a series of links 861 to achieve greater bending range. In this example, the link 861 may be similar to the links 802, 804, but the rolling surface and involute surface geometries may be repeated such that each outer link member 862 in the series includes both involute projections 864 and recesses 866. and each inner link member 868 includes rolling surfaces (not visible) on both ends of the link member. In this example, the articulating geometries are repeated, without rotation, about the central axis C2 so that the articulation section 860 is bendable in a single plane (either direction).

[0070] FIG. 14 illustrates an articulation section 870 (e.g., 330) that may include a series of links 871 to achieve greater bending range. In this example, the link 871 may be similar to the links 802, 804, but the rolling surface and involute surface geometries may be repeated such that each outer link member 872 in the series includes both involute projections 874 and recesses 876. and each inner link member 878 includes rolling surfaces 879 on both ends of the link member. In this example, the articulating geometries are repeated, with 90 degree rotation, about the central axis C2 so that the articulation section 870 is bendable in a two planes (four directions) or able to articulate in combined adjacent directions to achieve omnidirectional steering.

[0071] FIG. 15 illustrates a medical instrument system 880 which may include a distal articulation section 882 and an optional wrist mechanism 884. Each of the articulation section 882 and the wrist mechanism 884 may be articulated independently with dedicated articulation members. For examples, four articulation members may actuate four-direction steering of the articulatio section 882 and four separate articulation members may actuate four-direction steering of the wrist mechanism 884.

[0072] In some examples, the layered series of links may be cut (e.g., laser cut) from nested, thin-walled tubes. In particular, detailed features such as the involute surfaces may be carefully cut with laser cutting. A relatively stiff material such as a stainless steel hypotube may be suitable to reduce material deformation under the high axial loads. In some examples, struts or other structural members may be retained between the links as the tube is cut. At a later stage of the manufacturing process or before the medical instrument is deployed, the struts or structural members may then be removed to allow for bending at the joints.

[0073] In addition to the load bearing properties previously described, the dual layer rolling architecture of the link section 800 and articulation sections constructed of such link sections may be particularly suitable for non-antagonistic drive designs, as compared to pivoting or flexure joints. FIG. 16 illustrates an articulation section 890 in a non-antagonistic drive design. The articulation section 890 includes a plurality of serially coupled links 891 (e.g., links 802. 804 with the nested layer, rolling design) and two opposing control members 892, 893 be wrapped around a common drive capstan 894. A common drive capstan may be used, for example, to reduce the number of motors on a robotic manipulator without reducing the degrees of freedom of motion. A non-antagonistic design may inherently give as much pay-out on the control member 892 as it pulls in on the control member 893 because the two control members are fixed to the same capstan and are thus forced to pay-in and pay-out in the same amounts. For flexible medical instrument systems with long series of links, such as articulation section 890, slack in the non-tensioned control member 893 may develop due to stretching of the tensioned control member 892 and compression of the joints under compressive load. Thus, as the tensioned control member 892 pulls in an extra length to account for the cable stretch and joint compression, it also pays out the same amount of the opposing control member 893. Because the opposing control member 893 is not under the same or any load, it is therefore not experiencing the same stretch and compression as the tensioned control member 892. This causes slack to form in the opposing control member 893. Excess slack on the opposing control member 893 may affect control responsiveness and joint stability . With the rolling design of the joint section 800, as the joint bends, the neutral axis of the joint may shift in the direction of the tensioned control member 892. As the distance between the control member 892 and the neutral axis is reduced, less control member travel is required on the tensioned side and more payout is required on the opposing control member 893. The design of the rolling geometry' of joint section 800 may be tuned to the expected articulation forces of the joint, and thus the extra control member length in control member 893 created on the outside of the bend can be sufficient to neutralize or take up any extra slack caused by the non-antagonistic design.

[0074] FIG. 17 illustrates a cross-sectional view of an outer link member 1200 and an inner link member 1202 with a retaining system 1204. The inner and outer link members 1200, 1202 and the retaining system 1204 may be components of a link 1205. The retaining system 1204 may include retaining members 1206 and a curved yoke member 1208 joining the retaining members. The yoke member 1208 may include an opening 1209 and may extend in an arc approximately 270 degrees. The yoke member 1208 may have a curved profde or shape in some embodiments but may have alternative shapes depending on the desired overall profile of the link 1205. Optionally, the outer and inner link members may be coupled at fixation locations 1210 by. for example, laser welding. To assemble the retaining system 1204 to the outer and inner links 1200, 1202, the curved yoke member 1208 may be flexed to expand the opening 1209 and extend around the outside of outer link member 1200. The retaining members 1206 may be aligned with openings 1211 through the outer and inner link members 1200, 1202 and snapped into the openings. With the retaining member 1206 inserted through the link members 1200, 1202, the curved yoke member 1208 may relax to its original unexpanded shape or to a slightly expanded shape that continues to apply a light force that presses the yoke member 1208 toward the outer link member 1200. A control cable, function cable, tension element, or other flexible element may extend through a passage 1207 in each of the retaining members 1206. In some examples, the retaining members may provide a mechanical coupling between the inner link members to the outer link members as an addition or alternative to other fixation techniques such as laser welding. In some examples, the outer link member 1200 may include a circumferential recess or channel into which the yoke member 1208 may extend so the yoke member is flush with the outer surface of the outer link member 1200. In some examples, a recess may be omitted and the yoke member may extend around the outer surface of the outer link member 1200. In some examples, a braid, woven sleeve, or other retaining sheath may be applied around the outer link member 1200, after the retaining system 1204 is installed, to further secure the retaining system to the outer link member. In some examples, the retaining system may be formed of a metal (e.g., stainless steel), a shape-memory alloy (e.g., nitin ol), or a polymer. A polymer construction may further serve to reduce friction between the retaining members and the cables extending therethrough. In some examples, lubricant or polytetrafluoroethylene (PTFE) coating on the retaining members may further serve to reduce friction. In this example, the retaining system 1204 includes four retaining members 1206, but more or fewer retaining members may be used, depending on the number of cables to be retained and the permissible longitudinal spacing between retraints. In some examples, the retaining system may be a two-piece system with two retaining members connected by, for example, a 90 degree or 180 degree yoke member in each piece of the system. A two-piece system may reduce the amount of outer wall material removed to accommodate an inset yoke member. In some examples, each link may include two retaining members 1206 spaced 180 degrees apart and the pattern of the retaining members may be rotated 90 degrees in each successive layer (e g., parallel planes) of links.

[0075] FIG. 18A illustrates a sectional view of an articulation section 1300. The articulation section 1300 may be similar to the articulation section 870 that is bendable in a two planes (four directions) or able to articulate in combined adjacent directions to achieve omnidirectional steering. In this example, the articulation section 1300 includes ajoint section 1302 including a link 1304 in contact with a link 1306. The link 1304 may include an inner link member 1308 and an outer link member 1310 surrounding the inner link member. The link 1306 may include an inner link member 1312 and an outer link member 1314 surrounding the inner link member 1312. The inner link members 1308, 1312 may form an inner link layer or assembly, and the outer link members 1310, 1314 may form an outer link layer or assembly. The inner link assembly may be coupled to and extend within the outer link assembly. In this example, the inner link assembly may form a pivot joint 1316 (e.g., a ball and socket joint) which may constrain torsional movement and axial tension, thus minimizing longitudinal separation and relative twist. The outer link assembly may form a rolling joint 1318. supporting compressive stiffness in the articulation section and providing compression and friction relief to the inner pivot joint. In this example, the outer link member 1310 may be lanced to form retaining members 1320 that extends radially inward.

[0076] In some examples, the articulation section 1300 may be formed from two tubes (e.g.. hypotubes) sized such that one may extend within a lumen of the other. The features of the joints and retaining members may be machined from the tubes, for example by laser cutting. For example, outer link members 1310, 1314, the rolling joint 1318, and the retaining member 1320 may be formed by cutting a first single continuous outer tube, and the inner link members 1308, 1312 may be formed by cutting a second single continuous inner tube. After the tubes are cut and the features formed, the inner tube may be inserted into the outer tube and fixed, for example by laser welding. To maintain sufficient structural integrity during the handling and fixation, sacrificial members 1313 (e.g., FIG. 18B) may be cut in one or both of the tubes and removed after the outer tube is fixed to the inner tube. In some examples, removal of the sacrificial members may separate portions of the cut tube into a plurality of discrete sections such that the walls of the inner and/or outer tubes are no longer continuous. For example, the pivot joint 1316 may be formed from the same inner tube as a pivot joint 1317. The amount of maximum articulation of the pivotjoint 1316 may be determined by the spacing 1319 (e.g., the amount of material removed) between the machined ball and socket components. With the joint portions of the inner tube fixed to the outer tube and the sacrificial members of the inner tube removed, the two pivot joints 1316, 1317 may be separate and no longer connected by contiguous portions of the inner tube. In some examples, removal of the sacrificial member(s) may be accomplished by vibrating the welded tube structure to separate the material. In other examples, a tool may be applied to separate each sacrificial member.

[0077] Removal of the sacrificial members of the inner tube may allow space for insertion of elongate accessory components such as electrical cabling, illumination fibers, imaging devices, and/or optical fiber sensors and thus may reduce the overall diameter of the instrument. In examples where minimizing instrument diameter and maximization of internal working space is less critical, the use of sacrificial members may be avoided.

[0078] FIG. 18B illustrates a cross-sectional view of the link 1304. The sacrificial members

1313, which may be removed after the inner tube is fixed to the outer tube, are shown in dotted lines. A flexible working channel 1322 may extend axially through the articulation section 1300 to accommodate passage of various instruments. [0079] In any of the examples provided herein, the contact or joint configuration of the inner and outer link assemblies may be swapped. For example, in an alternative example of articulation section 1300, the outer link assembly or layer may include ball and socket components and the inner link assembly or layer may include a rolling joint.

[0080] FIG. 19A illustrates a partial sectional view of an articulation section 1400. The articulation section 1400 may be similar to the articulation section 870 that is bendable in a two planes (four directions) or able to articulate in combined adjacent directions to achieve omnidirectional steering. In this example, the articulation section 1400 includes a joint section 1402 including a link 1404 in contact with a link 1406. The link 1404 may include an inner link member 1408 and an outer link member 1410 surrounding the inner link member. The link 1406 may include an inner link member 1412 and an outer link member 1414 surrounding the inner link member 1412. The inner link members 1408, 1412 may form an inner link layer or assembly, and the outer link members 1410, 1414 may form an outer link layer or assembly. The inner link assembly may be coupled to and extend within the outer link assembly. In FIG. 19A, the outer link layer is shown in cross-section with the inner link layer made visible. In this example, the inner link assembly may form a rolling joint 1416 which may support compressive stiffness in the articulation section and provide compression and friction relief to the outer pivot joint. The outer link assembly may form a pivot joint (e.g., a ball and socket joint) 1418, constraining torsional movement and axial tension, thus minimizing longitudinal separation and relative twist. In this example, the inner link member 1408 may be lanced to form retaining members 1420 that extends radially inward.

[0081] In some examples, the articulation section 1400 may be formed from two tubes (e.g., hypotubes) sized such that one may extend within a lumen of the other. The features of the joints and retaining members may be machined from the tubes, for example by laser cutting. F or example, outer link members 1410, 1414 and the pivot j oint 1418 may be formed by cutting a first single continuous outer tube, and the inner link members 1408, 1412, the rolling joint 1416, and the retaining member 1420 may be formed by cutting a second single continuous inner tube. After the tubes are cut and the features formed, the inner tube may be inserted into the outer tube and fixed, for example by laser welding. To maintain sufficient structural integrity during the handling and fixation, sacrificial members 1413 may be cut in one or both of the tubes and removed after the outer tube is fixed to the inner tube. In some examples, removal of the sacrificial members may separate portions of the cut tube so that the walls of the inner or outer tubes are no longer continuous. For example, the rolling joint 1416 may be formed from the same inner tube as a rolling joint 1417. In some examples, removal of the sacrificial member(s) 1413 may be accomplished by vibrating the welded tube structure to separate the material. In other examples, a tool may be applied to separate each sacrificial member. Optionally, portions of the inner tube may be removed to allow space for insertion of elongate components such as electrical cabling, illumination fibers, imaging devices, and/or optical fiber sensors and thus may reduce the overall diameter of the instrument. FIG. 19B illustrates a cross-sectional view of the link 1404. A flexible working channel 1422 may extend axially through the articulation section 1400 to accommodate passage of various instruments. [0082] FIG. 20 illustrates a partially transparent view of an articulation section 1500 with a serpentine flexure joint 1518. The articulation section 1500 may be similar to the articulation section 870 that is bendable in a two planes (four directions) or able to articulate in combined adjacent directions to achieve omnidirectional steering. In this example, the articulation section 1500 includes a joint section 1502 including a link 1504 in contact with a link 1506. The link 1504 may include an inner link member 1508 and an outer link member 1510 (partially transparent) surrounding the inner link member. The link 1506 may include an inner link member 1512 and an outer link member 1514 (partially transparent) surrounding the inner link member 1512. The inner link members 1508, 1512 may form an inner link layer or assembly, and the outer link members 1510, 1514 may form an outer link layer or assembly. The inner link assembly may be coupled to and extend within the outer link assembly. In this example, the inner link assembly may form a rolling joint 1516 which may support axial compressive stiffness in the articulation section and provide compression relief to the outer serpentine flexure joint 1518. The rolling joint 1516 may experience less friction than a pivot joint (e.g., a ball and socket joint), but may provide less tensile and torsional integrity than a pivot joint. The outer link assembly may be coupled by the serpentine flexure joint (e.g., a ball and socket joint) 1518. The serpentine flexure joint 1518 may allow for some axial alignment tolerance and may provide some bending stiffness that biases the joint toward a straighten configuration when bending forces are reduced. As compared to a simple, hinge flexure joint, the serpentine shape may add length to the flexing beam without extending the overall length of the articulation section and may distribute strain while keeping the strain below the plastic limit for the material. The serpentine flexure may be formed of any material, including polymers or metal materials. For example, the articulation section 1500 may be formed from stainless steel, which may be economical and may allow for welding of the inner and outer tubes. Stainless steel may, however, yield more quickly than other materials. The use of a serpentine flexure joint may distribute strains and promote longer instrument life. In some examples, the serpentine shape, thickness, and/or number of switchbacks may be varied axially at a particular serpentine flexure or at successive serpentine joints in an articulation section to create variable bending stiffness. For example, flexure joints at a proximal region of an articulation section may be less flexible than flexure joints at a distal region. Optionally, a portion of the inner tube may be removed to allow space 1515 for insertion of elongate components such as electrical cabling, illumination fibers, imaging devices, and/or optical fiber sensors and thus may reduce the overall diameter of the instrument. In alternative examples, the serpentine flexure joint may join the inner link members and another type of joint may join the outer link members.

[0083] FIG. 21 illustrates a partially transparent view of an articulation section 1600 with a serpentine flexure joint 1618. The articulation section 1600 may be similar to the articulation section 1500 with the difference that an inner link member 1608 and an inner link member 1612 may be connected by a pivot joint 1616 (e.g., a ball and socket joint). In some examples, although a pivot joint may experience greater friction than a rolling j oint, the pivot joint may provide greater tensile integrity and greater torsional strength than a rolling j oint.

[0084] FIG. 22 illustrates a joint section 1702 with a serpentine flexure joint 1718 and an involute joint 1716. The joint section 1702 includes a link 1704 in contact with a link 1706. The links 1704, 1706 may be multi-layer or single layer links. The links 1704, 1706 may form a link assembly. In this example, the link assembly may include multiple joint forms. For example, the involute joint 1716 may support axial compressive stiffness and torsional stiffness in the articulation section and provide compression relief to the serpentine flexure joint 1718. The serpentine flexure joint 1718 may extend without the projection of the involute joint 176 and may allow for some axial alignment tolerance. The serpentine flexure joint 1718 may also provide some bending stiffness that biases the joint toward a straighten configuration when bending forces are reduced. As compared to a simple, hinge flexure joint, the serpentine shape may add length to the flexing beam without extending the overall length of the articulation section and may distribute strain while keeping the strain below the plastic limit for the material. The serpentine flexure may be formed of any material, including polymers or metal materials. The use of a serpentine flexure joint may distribute strains and promote longer instrument life. The length of the serpentine flexure joint may be chosen based on the anticipated amount of articulation and the material properties. In some examples, the serpentine shape, thickness, and/or number of switchbacks may be varied. In some examples, the serpentine flexure joint 1718 may include one or more projections 1720 that may prevent over compression of the serpentine joint and help reduce friction in the involute joint 1716. In some examples, the inner curves 1722 of the serpentine flexure joint 1718 may be rounded to provide stress relief at these bending locations. [0085] FIG. 23 A illustrates a side view of an articulation section 1800, and FIG. 23B illustrates a cross-sectional view of the articulation section 1800. In this example, the articulation section 1800 includes an inner link member 1808 and an inner link member 1812. The inner link members 1808, 1812 may form an inner link layer or assembly. In this example, the inner link assembly may form a rolling joint 1816. An outer flexible layer 1804 may be fixed to the inner link assembly. For example, the inner link assembly may extend within the outer link assembly and may be welded or otherwise fixed at fixation locations 1805. The outer flexible layer 1804 may include a tubular member 1806 with a helical or spiral slot 1807. The width and length of the slot 1807 may be selected to impart a desired bending stiffness to the outer flexible layer 1804. For example, a wide slot leaving less material of the tubular member may result in a more flexible articulation section than a narrow slow leaving more material. In some examples, the width of the slot may vary along the axial length of the articulation section. For example, the slot may be wider at a distal portion of the articulation section and narrower at a proximal portion of the articulation section to impart greater stiffness (less flexibility) at the proximal portion and less stiffness (greater flexibility’) at the distal portion. In this example, the tubular member 1806 may be lanced to form retaining members 1820 that extend radially inward.

[0086] In some examples, the articulation section 1800 may be formed from two tubes (e.g., hypotubes) sized such that one may extend within a lumen of the other. An inner tube may form the inner link members 1808, 1812 and an outer tube may form the outer flexible layer 1804. In this example, arcuate spacing 1818 between the outer flexible layer 1804 and the link members 1808, 1812 may house, for example electrical cabling 1814, elongate sensors 1819, illumination fibers, and/or imaging devices. In some examples the remaining space in the arcuate spacing 1818 may be filled with flexible filler material, such as elongate, flexible polymer rods, nitinol rods, or radiopaque material. The filler material may help maintain the position of the housed components.

[0087] FIG. 24 illustrates a robotically-assisted medical system, according to some examples. As shown in FIG. 24, a robotically-assisted medical system 900 may include a manipulator assembly 902 for operating a medical instrument system 904 (e.g., instrument system 200, 300, 400, 500 or any of the instrument systems or instrument system components described herein) in performing various procedures on a patient P positioned on a table T in a surgical environment 901. The manipulator assembly 902 may be teleoperated, nonteleoperated, or a hybrid teleoperated and non-tel eoperated assembly with select degrees of freedom of motion that may be motorized and/or teleoperated and select degrees of freedom of motion that may be non-motorized and/or non-teleoperated. A master assembly 906, which may be inside or outside of the surgical environment 901, generally includes one or more control devices for controlling manipulator assembly 902. Manipulator assembly 902 supports medical instrument 904 and may optionally include a plurality of actuators or motors that drive inputs on medical instrument 904 in response to commands from a control system 912. The actuators may optionally include transmission or drive systems that when coupled to medical instrument 904 may advance medical instrument 904 into a naturally or surgically created anatomic orifice. Other transmission or drive systems may move the distal end of medical instrument in multiple degrees of freedom, which may include three degrees of linear motion (e.g., linear motion along the X, Y, Z Cartesian axes) and in three degrees of rotational motion (e.g., rotation about the X. Y, Z Cartesian axes). For example, the transmission systems may actuate control members of the instrument system 300, 400, 500 or other instrument systems described herein. The manipulator assembly 902 may support various other systems for irrigation, treatment, or other purposes. Such systems may include fluid systems (including, for example, reservoirs, heating/cooling elements, pumps, and valves), generators, lasers, interrogators, and ablation components.

[0088] Robotically-assisted medical system 900 also includes a display system 910 for displaying an image or representation of the surgical site and medical instrument 904 generated by an imaging system 909 which may include an endoscopic imaging system. Display system 910 and master assembly 906 may be oriented so an operator O can control medical instrument 904 and master assembly 906 with the perception of telepresence. Any of the previously described graphical user interfaces may be display able on a display system 910 and/or a display system of an independent planning workstation.

[0089] In some examples, the endoscopic imaging system components of the imaging system 909 may be integrally or removably coupled to medical instrument system 904. However, in some examples, a separate endoscope, attached to a separate manipulator assembly may be used with medical instrument system 904 to image the surgical site. The endoscopic imaging system 909 may be implemented as hardware, firmware, software, or a combination thereof which interact with or are otherwise executed by one or more computer processors, which may include the processors of the control system 912.

[0090] Robotically-assisted medical system 900 may also include sensor system 908. The sensor system 908 may include a position/location sensor system (e.g., an actuator encoder or an electromagnetic (EM) sensor system) and/or a shape sensor system (e.g., an optical fiber shape sensor) for determining the position, orientation, speed, velocity, pose, and/or shape of the medical instrument 904. The sensor system 908 may also include temperature, pressure, force, or contact sensors or the like.

[0091] Robotically-assisted medical system 900 may also include control system 912. Control system 912 includes at least one memory 916 and at least one computer processor 914 for effecting control between medical instrument 904, master assembly 906, sensor system 908, and display system 910. Control system 912 also includes programmed instructions (e.g., a non-transitory machine-readable medium storing the instructions) to implement instrument actuation using the robotically-assisted medical system including for navigation and steering.

[0092] Control system 912 may optionally further include a virtual visualization system to provide navigation assistance to operator O when controlling medical instrument 904 during an image-guided surgical procedure. Virtual navigation using the virtual visualization system may be based upon reference to an acquired pre-operative or intra-operative dataset of anatomic passageways. The virtual visualization system processes images of the surgical site imaged using imaging technology such as computerized tomography (CT), magnetic resonance imaging (MRI), fluoroscopy, thermography, ultrasound, optical coherence tomography (OCT), thermal imaging, impedance imaging, laser imaging, nanotube X-ray imaging, and/or the like. The control system 912 may use a pre-operative image to locate the target tissue (using vision imaging techniques and/or by receiving user input) and create a pre-operative plan.

[0093] FIG. 25 A is a simplified diagram of a medical instrument system 1000 according to some embodiments. In some embodiments, medical instrument system 1000 may be used as the medical instrument systems 100, 200, 300, 400, 500, 600, 700, 880, 904 in an image-guided medical procedure. In some examples, medical instrument system 1000 may be used for non- teleoperational exploratory procedures or in procedures involving traditional manually operated medical instruments, such as endoscopy.

[0094] Medical instrument system 1000 includes elongate flexible device 1002, such as a flexible catheter or endoscope, coupled to a drive unit 1004. Elongate device 1002 includes a flexible body 1016 having proximal end 1017 and distal end, or tip portion, 1018. In some embodiments, flexible body 1016 has an approximately 14-20 mm outer diameter. Other flexible body outer diameters may be larger or smaller. Any of the counter motion mechanisms and rolling joints described in the examples above may be used in the construction for the flexible device 1002. [0095] Medical instrument system 1000 optionally includes a tracking system 1030 for determining the position, orientation, speed, velocity, pose, and/or shape of distal end 1018 and/or of one or more segments 1024 along flexible body 1016 using one or more sensors and/or imaging devices. The entire length of flexible body 1016, between distal end 1018 and proximal end 1017, may be effectively divided into segments 1024. Tracking system 1030 may optionally be implemented as hardware, firmware, software or a combination thereof which interact with or are otherwise executed by one or more computer processors, which may include the processors of control system 912 in FIG. 12.

[0096] Tracking system 1030 may optionally track distal end 1018 and/or one or more of the segments 1024 using a shape sensor 1022. In some embodiments, tracking system 1030 may optionally and/or additionally track distal end 1018 using a position sensor system 1020, such as an electromagnetic (EM) sensor system. In some examples, position sensor system 1020 may be configured and positioned to measure six degrees of freedom, e.g., three position coordinates X, Y, Z and three orientation angles indicating pitch, yaw, and roll of a base point or five degrees of freedom, e.g., three position coordinates X. Y, Z and two orientation angles indicating pitch and yaw of a base point.

[0097] Flexible body 1016 includes one or more channels 1021 sized and shaped to receive one or more medical instruments 1026. In some examples, the counter motion mechanism and rolling joints described in the examples above may be used in the construction for the instruments 1026. In some embodiments, flexible body 1016 includes two channels 1021 for separate instruments 1026, however, a different number of channels 1021 may be provided. FIG. 25B is a simplified diagram of flexible body 1016 with medical instrument 1026 extended according to some embodiments. In some embodiments, medical instrument 1026 may be used for procedures such as surgery, biopsy, ablation, illumination, irrigation, or suction. Medical instrument 1026 can be deployed through channel 1021 of flexible body 1016 and used at a target location within the anatomy. Medical instrument 1026 may include, for example, image capture probes, biopsy instruments, laser ablation fibers, and/or other surgical, diagnostic, or therapeutic tools. Medical tools may include end effectors having a single working member such as a scalpel, a blunt blade, an optical fiber, an electrode, and/or the like. Other end effectors may include, for example, forceps, graspers, scissors, clip appliers, and/or the like. Other end effectors may further include electrically activated end effectors such as electrosurgical electrodes, transducers, sensors, and/or the like. Medical instrument 1026 may be advanced from the opening of channel 1021 to perform the procedure and then retracted back into the channel when the procedure is complete. Medical instrument 1026 may be removed from proximal end 1017 of flexible body 1016 or from another optional instrument port (not shown) along flexible body 1016.

[0098] Medical instrument 1026 may additionally house cables, linkages, or other actuation controls (not shown) that extend between its proximal and distal ends to controllably the bend distal end of medical instrument 1026. Flexible body 1016 may also house cables, linkages, or other steering controls (not shown) that extend between drive unit 1004 and distal end 1018 to controllably bend distal end 1018 as shown, for example, by broken dashed line depictions 1019 of distal end 1018. In some examples, at least four cables are used to provide independent “up-do wn” steering to control a pitch of distal end 1018 and “left-right'’ steering to control a yaw of distal end 1018. In embodiments in which medical instrument system 1000 is actuated by a robot-assisted assembly, drive unit 1004 may include drive inputs that removably couple to and receive power from drive elements, such as actuators, of the teleoperational assembly. In some embodiments, medical instrument system 1000 may include gripping features, manual actuators, or other components for manually controlling the motion of medical instrument system 1000. The information from tracking system 1030 may be sent to a navigation system 1032 where it is combined with information from visualization system 1031 and/or the preoperatively obtained models to provide the physician or other operator with real-time position information. In the description, specific details have been set forth describing some examples. Numerous specific details are set forth to provide a thorough understanding of the examples. It will be apparent, however, to one skilled in the art that some examples may be practiced without some or all these specific details. The specific examples disclosed herein are meant to be illustrative but not limiting. One skilled in the art may realize other elements that, although not specifically described here, are within the scope and the spirit of this disclosure.

[0099] Elements described in detail with reference to one example, implementation, or application optionally may be included, whenever practical, in other examples, implementations, or applications in which they are not specifically shown or described. For example, if an element is described in detail with reference to one example and is not described with reference to a second example, the element may nevertheless be claimed as included in the second example. Thus, to avoid unnecessary repetition in the description, one or more elements shown and described in association with one example, implementation, or application may be incorporated into other examples, implementations, or aspects unless specifically described otherwise, unless the one or more elements would make an example or implementation non-functional, or unless two or more of the elements provide conflicting functions. Not all the illustrated processes may be performed in all examples of the disclosed methods. Additionally, one or more processes that are not expressly illustrated in may be included before, after, in between, or as part of the illustrated processes. In some examples, one or more of the processes may be performed by a control system or may be implemented, at least in part, in the form of executable code stored on non-transitory, tangible, machine- readable media that when run by one or more processors may cause the one or more processors to perform one or more of the processes.

[0100] Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In addition, dimensions provided herein are for specific examples and it is contemplated that different sizes, dimensions, and/or ratios may be utilized to implement the concepts of the present disclosure. To avoid needless descriptive repetition, one or more components or actions described in accordance with one illustrative example can be used or omitted as applicable from other illustrative examples. For the sake of brevity, the numerous iterations of these combinations will not be described separately. For simplicity, in some instances the same reference numbers are used throughout the drawings to refer to the same or like parts.

[0101] The systems and methods described herein may be suited for imaging and treatment , via natural or surgically created connected passageways, in any of a variety of anatomic systems, including the lung, colon, the intestines, the stomach, the liver, the kidneys and kidney calices, the brain, the heart, the circulatory⁷ system including vasculature, and/or the like. While some examples are provided herein with respect to medical procedures, any reference to medical or surgical instruments and medical or surgical methods is non-limiting. For example, the instruments, systems, and methods described herein may be used for non-medical purposes including industrial uses, general robotic uses, and sensing or manipulating non-tissue work pieces. Other example applications involve cosmetic improvements, imaging of human or animal anatomy, gathering data from human or animal anatomy, and training medical or nonmedical personnel. Additional example applications include use for procedures on tissue removed from human or animal anatomies (without return to a human or animal anatomy) and performing procedures on human or animal cadavers. Further, these techniques can also be used for surgical and nonsurgical medical treatment or diagnosis procedures.

[0102] One or more elements in examples of this disclosure may be implemented in software to execute on a processor of a computer system such as control processing system. When implemented in software, the elements of the examples of this disclosure may be code segments to perform various tasks. The program or code segments can be stored in a processor readable storage medium or device that may have been downloaded by way of a computer data signal embodied in a carrier wave over a transmission medium or a communication link. The processor readable storage device may include any medium that can store information including an optical medium, semiconductor medium, and/or magnetic medium. Processor readable storage device examples include an electronic circuit; a semiconductor device, a semiconductor memory device, a read only memory (ROM), a flash memory, an erasable programmable read only memory' (EPROM); a floppy diskette, a CD-ROM, an optical disk, a hard disk, or other storage device. The code segments may be downloaded via computer networks such as the Internet, Intranet, etc. Any of a wide variety of centralized or distributed data processing architectures may be employed. Programmed instructions may be implemented as a number of separate programs or subroutines, or they may be integrated into a number of other aspects of the systems described herein. In some examples, the control system may support wireless communication protocols such as Bluetooth. Infrared Data Association (IrDA), HomeRF, IEEE 802.11, Digital Enhanced Cordless Telecommunications (DECT), ultra-wideband (UWB), ZigBee, and Wireless Telemetry.

[0103] Note that the processes and displays presented might not inherently be related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the operations described. The required structure for a variety of these systems will appear as elements in the claims. In addition, the examples of the invention are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein.

[0104] This disclosure describes various instruments, portions of instruments, and anatomic structures in terms of their state in three-dimensional space. As used herein, the term position refers to the location of an object or a portion of an object in a three-dimensional space (e.g., three degrees of translational freedom along Cartesian x-, y-, and z-coordinates). As used herein, the term orientation refers to the rotational placement of an object or a portion of an object (e.g., in one or more degrees of rotational freedom such as roll, pitch, and/or yaw). As used herein, the term pose refers to the position of an object or a portion of an object in at least one degree of translational freedom and to the orientation of that object or portion of the object in at least one degree of rotational freedom (e.g., up to six total degrees of freedom). As used herein, the term shape refers to a set of poses, positions, or orientations measured along an object.

[0105] While certain illustrative examples of the invention have been described and shown in the accompanying drawings, it is to be understood that such examples are merely illustrative of and not restrictive on the broad invention, and that the examples of the invention are not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.

Claims

CLAIMS What is claimed is:

1. A counter motion mechanism comprising: a flexible elongate device extending along a central axis, the flexible elongate device comprising: a first articulation section including a first plurality of serial flexible links bendable along a translational direction, a second articulation section including a second plurality of serial flexible links bendable along the translational direction, and a transition section extending between the first and second articulation sections; and a control member extending between the first articulation section and the second articulation section and wrapping approximately 180 degrees about a central axis at the transition section, wherein the control member is configured to bend the first articulation section in a first direction as the second articulation section bends in a second direction opposite the first direction while a first link of the first articulation section and a second link of the second articulation section are maintained in a parallel orientation, wherein a translational distance extends in the translational direction, between an axis of the first link and an axis of the second link, and wherein the translational distance includes a first distance component associated with the bent first articulation section, a second distance component associated with the bent second articulation section, and a third distance component associated with the transition section.

2. The counter motion mechanism of claim 1 , further comprising a flexible guide tube coupled to the transition section, wherein the control member extends through the flexible guide tube to wrap the approximately 180 degrees about the central axis.

3. The counter motion mechanism of claim 2, wherein the flexible guide tube includes a spring.

4. The counter motion mechanism of claim 1, further comprising a flexible guide tube coupled to the first articulation section, wherein the control member extends through the flexible guide tube along the first articulation section.

5. The counter motion mechanism of claim 4, wherein the flexible guide tube includes a spring.

6. The counter motion mechanism of claim 1, further comprising a flexible guide tube coupled to the second articulation section, wherein the control member extends through the flexible guide tube along the second articulation section.

7. The counter motion mechanism of claim 6, wherein the flexible guide tube includes a spring.

8. The counter motion mechanism of claim 1, wherein the first articulation section, the second articulation section, and the transition section are formed from a single continuous tube.

9. The counter motion mechanism of claim 1, wherein the control member is a first control member of a plurality of control members extending between the first articulation section and the second articulation section and wrapping 180 degrees about the central axis at the transition section.

10. The counter motion mechanism of claim 1, wherein the first articulation section includes a joint that includes the first link and a third link, the first link including a first inner link member and a first outer link member surrounding the first inner link member, and the third link including a third inner link member and a third outer link member surrounding the third inner link member, wherein the first inner link member and the third inner link member are pivotally engaged to form an inner link assembly, wherein the first outer link member and the third outer link member are pivotally engaged to form an outer link assembly, and wherein the inner link assembly is coupled to the outer link assembly to resist axial displacement between the inner and outer link assemblies.

11. The counter motion mechanism of claim 10 wherein one of the inner or outer link assemblies is pivotably engaged by a rolling joint and the other of the inner or outer link assemblies is pivotably engaged by an involute contact joint.

12. The counter motion mechanism of claim 11. wherein the inner link assembly is pivotably engaged by the rolling joint and wherein the outer link assembly is pivotably engaged by the involute contact joint.

13. The counter motion mechanism of claim 10, wherein the first inner link member is coupled to the first outer link member by a retaining member.

14. The counter motion mechanism of claim 13, wherein the retaining member includes a distended portion of a wall of the first outer fink member that interfaces with an aperture in a wall of the first inner link member.

15. The counter motion mechanism of claim 13, wherein the retaining member includes a compressible eyelet configured to extend through an aperture in a wall of the first inner link member.

16. A counter motion mechanism comprising: a flexible elongate device extending along a central axis, the flexible elongate device comprising: a first articulation section including a first link, a second articulation section including a second link, and a transition section extending between the first and second articulation sections; and a control member extending from a region proximal to the first articulation section to the second articulation section and wrapping approximately 180 degrees about a central axis at the transition section, wherein the control member is configured to bend the first articulation section in a first direction and the second articulation section in a second direction opposite the first direction while the control member maintains the first link and the second link in a parallel orientation, and wherein the control member maintains the parallel orientation without use of separate tension elements extending strictly between the first articulation section and the second articulation section to maintain the parallel orientation.

17. The counter motion mechanism of claim 16, further comprising a flexible guide tube coupled to the transition section, wherein the control member extends through the flexible guide tube to wrap the approximately 180 degrees about the central axis.

18. The counter motion mechanism of claim 17, wherein the flexible guide tube includes a spring.

19. The counter motion mechanism of claim 16. further comprising a flexible guide tube coupled to the first articulation section, wherein the control member extends through the flexible guide tube along the first articulation section.

20. The counter motion mechanism of claim 19. wherein the flexible guide tube includes a spring.

21. The counter motion mechanism of claim 16, further comprising a flexible guide tube coupled to the second articulation section, wherein the control member extends through the flexible guide tube along the second articulation section.

22. The counter motion mechanism of claim 21, wherein the flexible guide tube includes a spring.

23. The counter motion mechanism of claim 16, wherein the first articulation includes a first plurality⁷ of links including the first link, and the second articulation section includes a second plurality⁷ of links, including the second link.

24. The counter motion mechanism of claim 16. wherein the first articulation section, the second articulation section, and the transition section are formed from a single continuous tube.

25. The counter motion mechanism of claim 16. wherein the control member is a first control member of a plurality of control members extending between the first articulation section and the second articulation section and wrapping 180 degrees about the central axis at the transition section.

26. The counter motion mechanism of claim 16, wherein the first articulation section includes a joint that includes the first link and a third link, the first link including a first inner link member and a first outer link member surrounding the first inner link member, and the third link including a third inner link member and a third outer link member surrounding the third inner link member, wherein the first inner link member and the third inner link member are pivotally engaged to form an inner link assembly, wherein the first outer link member and the third outer link member are pivotally engaged to form an outer link assembly, and wherein the inner link assembly is coupled to the outer link assembly to resist axial displacement between the inner and outer link assemblies.

27. The counter motion mechanism of claim 26 wherein one of the inner or outer link assemblies is pivotably engaged by a rolling joint and the other of the inner or outer link assemblies is pivotably engaged by an involute contact joint.

28. The counter motion mechanism of claim 27. wherein the inner link assembly is pivotably engaged by the rolling joint and wherein the outer link assembly is pivotably engaged by the involute contact joint.

29. The counter motion mechanism of claim 26. wherein the first inner link member is coupled to the first outer link member by a retaining member.

30. The counter motion mechanism of claim 29, wherein the retaining member includes a distended portion of a wall of the first outer link member that interfaces with an aperture in a wall of the first inner link member.

31. The counter motion mechanism of claim 29, wherein the retaining member includes a compressible eyelet configured to extend through an aperture in a wall of the first inner link member.

32. A flexible elongate instrument assembly comprising: a joint section including a first link movably coupled to a second link, the first link including a first inner link member and a first outer link member surrounding the first inner link member, and the second link including a second inner link member and a second outer link member surrounding the second inner link member, wherein the first inner link member and the second inner link member are movably engaged to form an inner link assembly. wherein the first outer link member and the second outer link member are movably engaged to form an outer link assembly, and wherein the inner link assembly is coupled to the outer link assembly to resist axial displacement between the inner and outer link assemblies.

33. The flexible elongate instrument assembly of claim 32, wherein one of the inner or outer link assemblies is movably engaged by a rolling joint and the other of the inner or outer link assemblies in movably engaged by an involute contact joint.

34. The flexible elongate instrument assembly of claim 33, wherein the inner link assembly is movably engaged by the rolling joint and wherein the outer link assembly is movably engaged by the involute contact joint.

35. The flexible elongate instrument assembly of claim 32, wherein one of the inner or outer link assemblies is movably engaged by a rolling joint and the other of the inner or outer link assemblies in movably engaged by a serpentine flexure joint.

36. The flexible elongate instrument assembly of claim 32, further comprising a first retaining member extending radially inward of the flexible elongate instrument assembly, the first retaining member including a passage.

37. The flexible elongate instrument assembly of claim 36, wherein the passage is sized to receive a control member.

38. The flexible elongate instrument assembly of claim 37, further comprising the control member.

39. The flexible elongate instrument assembly of claim 36, further including a plurality of retaining members, including the first retaining member, wherein the plurality of retaining members are coupled by a yoke.

40. The flexible elongate instrument assembly of claim 36, wherein the first retaining member includes a distended portion of a wall of the first outer link member that interfaces with an aperture in a wall of the first inner link member.

41. The flexible elongate instrument assembly of claim 36, wherein the first retaining member includes a compressible eyelet configured to extend through an aperture in a wall of the first inner link member.

42. The flexible elongate instrument assembly of claim 32, wherein the inner link assembly is formed from a first continuous tube and the outer link assembly is formed from a second continuous tube.

43. The flexible elongate instrument assembly of claim 32, wherein the first inner link member includes a plurality of sections coupled to the outer link assembly and separated from each other.

44. The flexible elongate instrument assembly of claim 43, wherein a spacing between the plurality of sections is sized to receive an accessory component.

45. The flexible elongate instrument assembly of claim 32, further comprising a control member extending between the first and second joints.

46. The flexible elongate instrument assembly of claim 32, further comprising a counter motion mechanism including: a first articulation section including a first plurality of serial flexible links, a second articulation section including a second plurality⁷ of serial flexible links, a transition section extending between the first and second articulation sections; and a control member extending between the first articulation section and the second articulation section and wrapping approximately 180 degrees about a central axis at the transition section, wherein the joint section is included in the first articulation, and wherein the control member is configured to bend the first articulation section in a first direction as the second articulation section bends in a second direction opposite the first direction while a first link of the first articulation section and a third link of the second articulation section are maintained in a parallel orientation.

47. The flexible elongate instrument assembly of claim 46, wherein a translational distance extends between the first link and the third link, and wherein the translational distance includes a first distance component associated with the bent first articulation section, a second distance component associated with the bent second articulation section, and a third distance component associated with the transition section.

48. A flexible elongate instrument assembly comprising: an articulation section including an inner link assembly and an outer flexible layer surrounding the inner link assembly, wherein the inner link assembly includes a first inner link member movably engaged with a second inner link member, wherein the outer flexible layer includes a tubular member in which a helical slot is formed, and wherein the inner link assembly is coupled to the outer flexible layer to resist axial displacement between the inner link assembly and the outer flexible layer.

49. The flexible elongate instrument assembly of claim 48, wherein the outer flexible layer includes a retaining member extending radially inward.

50. The flexible elongate instrument assembly of claim 49, wherein the inner link assembly is fixed to the retaining member.

51. The flexible elongate instrument assembly of claim 48, wherein an arcuate spacing extends between the outer flexible layer and the inner link assembly.

52. The flexible elongate instrument assembly of claim 51, further comprising an accessory’ component extending through the arcuate spacing.

53. The flexible elongate instrument assembly of claim 52, further comprising a filling material extending within the arcuate spacing to control a position of the accessorycomponent.