WO2025085389A1

WO2025085389A1 - Miniature capstan actuators for surgical instruments

Info

Publication number: WO2025085389A1
Application number: PCT/US2024/051315
Authority: WO
Inventors: Bruce M. Schena
Original assignee: Intuitive Surgical Operations Inc
Current assignee: Intuitive Surgical Operations Inc
Priority date: 2023-10-16
Filing date: 2024-10-15
Publication date: 2025-04-24
Anticipated expiration: 2026-04-16

Abstract

A medical device includes one or more capstans distally spaced from a force transmission member and coupled to one or more elongate rotatable drive elements. The medical device further includes one or more tension elements that are each coupled to one of the one or more capstans and to a distal end of the medical device. A length of each of the one or more tension elements is configured to wrap around the capstan to which it is coupled, consequently exerting an axial force on the distal end of the medical device.

Description

MINIATURE CAPSTAN ACTUATORS FOR SURGICAL INSTRUMENTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Application No. 63/590,748, filed October 16, 2024, the entire contents of which are incorporated by reference herein in its entirety.

FIELD

[0002] The present disclosure is directed to miniature capstan actuators for surgical instruments.

BACKGROUND

[0003] Minimally invasive medical techniques are 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 to reach a target tissue location. Minimally invasive medical instruments include instruments such as therapeutic, diagnostic, biopsy, and surgical instruments. Medical instruments may be inserted into anatomic passageways and navigated toward a region of interest within a patient anatomy.

[0004] Some anatomic passageways, such as the gastrointestinal (GI) tract, are long and circuitous. Surgical instruments used for GI procedures such as Endoscopic Submucosal Dissection (ESD) and Endoscopic Mucosal Resection (EMR) may function through long, flexible working channels of standard or customized endoscopes or otherwise along such endoscopes, which can reach lengths exceeding 1.6 meters. Articulation of the instruments and/or the endoscopes may occur via tension elements (such as drive cables) that are wound around rotating capstans. The capstans may be operatively coupled to an external device such as a robotic manipulator and receive forces/torques from the manipulator to drive the instruments and/or the endoscope. However, with the long lengths of the instruments/endoscope and associated drive cables, capstan friction from moving tensioned cables through a tortuous path can impede actuation of the surgical instrument because capstan friction increases exponentially based on bend angle. Even small increases in bend angle can multiply the force loss to such a degree that a surgical instrument functions poorly or stops working entirely, and the cumulative bend angle to reach the cecum, for example, can exceed 360 degrees. In short, the design of flexible surgical instruments is impeded by the actuation challenges caused by capstan friction.

[0005] Instruments that can operate without unduly increasing capstan friction are needed to enable medical procedures.

SUMMARY

[0006] Consistent with some examples, a medical device may include a proximal force transmission member, an elongate shaft, one or more capstans, and one or more tension elements. The proximal force transmission member may include one or more rotatable inputs configured to receive forces or torques from an external device. The elongate shaft may have a proximal end coupled to the proximal force transmission member. The elongate shaft may house one or more elongate rotatable drive elements respectively coupled to one of the one or more rotatable inputs of the proximal force transmission member. The one or more capstans may be coupled to a distal end of the elongate shaft. The one or more capstans may each comprise a first end respectively coupled to one of the elongate rotatable drive elements. Each of the one or more capstans may be distally spaced from the force transmission member via the elongate shaft. Each of the one or more tension elements may be coupled to one of the one or more capstans and to a distal end of the medical device.

[0007] Consistent with some examples, a medical device may include a proximal force transmission member, an elongate shaft, one or more capstans, and one or more tension elements. The proximal force transmission member may include one or more rotatable inputs configured to receive forces or torques from an external device. The elongate shaft may have a proximal end coupled to the proximal force transmission member. The elongate shaft may house one or more elongate rotatable drive elements respectively coupled to one of the one or more rotatable inputs of the proximal force transmission member. The one or more capstans may be coupled to a distal end of the elongate shaft. The one or more capstans may each comprise a first end respectively coupled to one of the elongate rotatable drive elements. Each of the one or more tension elements may have a first end coupled to one of the one or more capstans, a second end directly coupled to a distal end of the medical device, and a length configured to wrap around the one of the one or more capstans. The second end of each of the one or more tension elements may be configured to exert an axial force on the distal end of the medical device as the length of the tension element is wrapped around the one of the one or more capstans. [0008] Consistent with some examples, a medical device includes a proximal force transmission member, an elongate shaft, one or more capstans, and one or more tension elements. The proximal force transmission member may include one or more rotatable inputs configured to receive forces or torques from an external device. The elongate shaft may have a proximal end coupled to the proximal force transmission member. The elongate shaft may house one or more elongate rotatable drive elements respectively coupled to the one or more rotatable inputs of the proximal force transmission member. The one or more capstans may be coupled to a distal end of the elongate shaft. The one or more capstans may each comprise a first end respectively coupled to the elongate rotatable drive elements and a capstan shaft having a capstan diameter. Each of the one or more tension elements may have a first end coupled to one of the one or more capstans, a second end coupled to a distal end of the medical device, and a tension element diameter. The ratio of the capstan diameter to the tension element diameter may be less than 10:1.

[0009] In an example, the one or more elongate rotatable drive elements may be a plurality of elongate rotatable drive elements, the one or more capstans may be a plurality of capstans, and the one or more tension elements may be a plurality of tension elements.

[0010] In an example, each of the one or more capstans may include a shaft, and each of the one or more tension elements may be configured to slide axially down the shaft of the one of the one or more capstans while being wrapped around the one of the one or more capstans.

[0011] In an example, each of the one or more tension elements may comprise a braided polymer.

[0012] In an example, each of the one or more tension elements may be lubricated.

[0013] In an example, the elongate shaft may be flexible.

[0014] In an example, the elongate shaft may be rigid.

[0015] In an example, each of the one or more tension elements may be pre- wound around the one of the one or more capstans to have an approximately constant effective gear ratio for subsequent wrapping.

[0016] In an example, at least one of the one or more capstans may have a shaft with a crosssection that changes along a longitudinal axis such that an effective gear ratio changes as one of the one or more tension elements is wrapped around the shaft of the at least one of the one or more capstans.

[0017] In an example, the medical device may be an endoscope and the change in the cross- section corresponds with a change in a bend angle of the endoscope.

[0018] In an example, the change in the cross-section may adjust an effective gear ratio to offset an increase in friction resulting from the change in the bend angle of the endoscope.

[0019] In an example, the distal end may be actuated manually when the medical device is decoupled from the external device.

[0020] In an example, the one or more capstans may be arranged in antagonistic pairs.

[0021] In an example, the elongate shaft has a length greater than or equal to one meter.

[0022] In an example, the medical device may further comprise a distal bulkhead, and the distal bulkhead may include one or more capstan pockets to each receive a respective capstan of the one or more capstans and a redirect aperture adjacent each capstan pocket for each of the one or more tension elements.

[0023] In an example, the redirect aperture adjacent each capstan pocket may be configured to redirect one of the one or more tension elements from a wrap angle relative to a longitudinal axis of the capstan to an axial angle substantially parallel to the longitudinal axis of the capstan.

[0024] In an example, the redirect aperture adjacent each capstan pocket may include a shoulder having a smooth surface.

[0025] In an example, each of the one or more capstans may have a second end including a conical section having a spherical domed tip.

[0026] In an example, the medical device may further include a proximal bulkhead coupled to the one or more capstans, and the proximal bulkhead may include a rotary bearing for each of the one or more capstans.

[0027] In an example, the first end of each of the one or more capstans may be positioned within a respective rotary bearing of the proximal bulkhead.

[0028] In some examples, the medical device may be a surgical instrument.

[0029] In some examples, the distal end of the medical device may be an end effector actuated by the one or more tension elements.

[0030] In some examples, the medical device may include a wrist mechanism and an end effector distal to the wrist mechanism, the wrist mechanism configured to be actuated by the one or more tension elements and configured for bidirectional motional along four axes.

[0031] In some examples, the medical device may further include an elbow mechanism and an end effector distal to the elbow mechanism, the elbow mechanism configured for bidirectional motion along four axes.

[0032] It is to be understood that both the foregoing general description and the following detailed description are exemplary 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

[0033] Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

[0034] FIG. 1 is a diagram of a first robotically-assisted manipulator system, in accordance with the present disclosure.

[0035] FIG. 2A illustrates an instrument system utilizing aspects of the present disclosure.

[0036] FIG. 2B illustrates a distal portion of the instrument system of FIG. 2A with an extended example of an instrument in accordance with the present disclosure.

[0037] FIG. 3 is a perspective view of a manipulator system in accordance with the present disclosure.

[0038] FIG. 4 is a schematic view of a manipulator system in accordance with the present disclosure.

[0039] FIG. 5 is a perspective view of a medical device according to an embodiment.

[0040] FIG. 6 is a perspective view of a distal end portion of the medical device of FIG. 5.

[0041] FIG. 7 is a side view of a plurality of capstans coupled to a distal end of an elongate shaft housing a plurality of elongate rotatable drive elements.

[0042] FIG. 8 is a perspective view of a proximal bulkhead configured to connect to one or more capstans.

[0043] FIG. 9 is a perspective view of a distal bulkhead configured to connect to a plurality of capstans and a plurality of tension elements. [0044] FIG. 10 is a perspective view of a capstan including fixation apertures, a shaft, and a spherical domed tip.

[0045] FIG. 11 is a perspective view of a capstan with a tension element wrapped around the capstan.

[0046] FIG. 12 is a schematic illustration of a method of preparing a medical device including capstans by pre-winding tension elements around the capstans.

[0047] FIG. 13 is a schematic illustration of a method of using a medical device including capstans by adjusting an effective gear ratio.

[0048] 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

[0049] In the following detailed description of the aspects of the invention, numerous specific details are set forth to provide a thorough understanding of the disclosed embodiments. However, it will be obvious to one skilled in the art that the embodiments of this disclosure may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the embodiments of the invention. And, to avoid needless descriptive repetition, one or more components or actions described in accordance with one illustrative embodiment can be used or omitted as applicable from other illustrative embodiments. 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.

[0050] One or more miniature capstans are provided that allow mechanical power to be delivered to a distal end of a medical device for effective actuation of the medical device without unduly increasing capstan friction. In various examples, the medical device is a surgical instrument (where, for example, an end effector and/or optional wrist mechanism may be attached), or an a elongate flexible device, such as an endoscope. Specifically, one or more tension elements coupled to the one or more capstans allow rotational motion to be converted into cable tension at or near the distal end of the medical device. The one or more capstans are distally spaced from a force transmission member and coupled to the force transmission member by elongate rotatable drive elements. Rotation of a capstan by an elongate rotatable drive clement causes a first end of a respective tension element coupled to the capstan to wrap around the capstan, thereby causing a second end of the tension element to exert an axial force on a distal end of the medical device. When two capstans are paired, the capstans can provide controlled bidirectional motion. A typical surgical instrument distal end can require three or more axes of motion. For example, a tissue grasper may include a pitch axis and two independent yaw axes. Synchronous movement of two tension elements resulting from synchronous rotation of their respective connected capstans along the independent yaw axes in the same direction provide a pure yaw motion of the tissue grasper, while movement of the two tension elements along the independent yaw axes in opposite directions to each other resulting from opposite rotation of their respective connected capstans provides a useful grasping motion. Other types of instruments, particularly those used in GI procedures, may use multi-segmented "snake-like" bending sections which can provide pitch and yaw motions. Each of the pitch or yaw axes typically require a bidirectional pair of capstans and respective tension elements. For this style of instrument, the grasping function may be actuated independently with another pair of capstans and respective tension elements, or some other actuation means. As illustrated and described herein, four pairs of capstans and respective tension elements can be provided to impart bidirectional motion along four axes without creating undue capstan friction that may impede use of the surgical instrument.

[0051] Turning to the drawings, FIGS. 1-6 of the drawings illustrate systems and medical instruments that can be adapted for use with one or more miniature capstans, and FIGS. 7-11 illustrate implementations and features of one or more miniature capstans.

[0052] FIG. 1 illustrates an embodiment of a robotically-assisted manipulator system for use with the rotary to linear force articulation members described herein. The manipulator system may be used, for example, in surgical, diagnostic, therapeutic, biopsy, or non-medical procedures, and is generally indicated by the reference numeral 100. As shown in FIG. 1, a robotically-assisted manipulator system 100 may include one or more manipulator assemblies 102 for operating one or more medical instrument systems 104 in performing various procedures on a patient P positioned on a table T in a medical environment 101. For example, the manipulator assembly 102 may drive catheter or end effector motion, may apply treatment to target tissue, and/or may manipulate control members. The manipulator assembly 102 may be teleoperated, non- teleoperated, or a hybrid teleoperated and non-teleoperated assembly with select degrees of freedom of motion that may be motorized and/or tclcopcratcd and select degrees of freedom of motion that may be non-motorized and/or non-teleoperated. An operator input system 106, which may be inside or outside of the medical environment 101, generally includes one or more control devices for controlling manipulator assembly 102. Manipulator assembly 102 supports medical instrument system 104 and may optionally include a plurality of actuators or motors that drive inputs on medical instrument system 104 in response to commands from a control system 112. The actuators may optionally include drive systems that when coupled to medical instrument system 104 may advance medical instrument system 104 into a naturally or surgically created anatomic orifice. Other 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). The manipulator assembly 102 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.

[0053] Robotically-assisted manipulator system 100 also includes a display system 110 for displaying an image or representation of the surgical site and medical instrument system 104 generated by an imaging system 109 which may include an endoscopic imaging system. Display system 110 and operator input system 106 may be oriented so an operator O can control medical instrument system 104 and operator input system 106 with the perception of telepresence. A graphical user interface may be displayable on the display system 110 and/or a display system of an independent planning workstation.

[0054] In some examples, the endoscopic imaging system components of the imaging system 109 may be integrally or removably coupled to medical instrument system 104. However, in some examples, a separate endoscope, attached to a separate manipulator assembly may be used with medical instrument system 104 to image the surgical site. The endoscopic imaging system 109 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 112.

[0055] Robotically-assisted manipulator system 100 may also include a sensor system 108. The sensor system 108 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 system 104. The sensor system 108 may also include temperature, pressure, force, or contact sensors or the like.

[0056] Robotically-assisted manipulator system 100 may also include a control system 112. Control system 112 includes at least one memory 116 and at least one computer processor 114 for effecting control between medical instrument system 104, operator input system 106, sensor system 108, and display system 110. Control system 112 also includes programmed instructions (e.g., a non-transitory machine-readable medium storing the instructions) to implement a procedure using the robotically-assisted manipulator system including for navigation, steering, imaging, engagement feature deployment or retraction, applying treatment to target tissue (e.g., via the application of energy), or the like.

[0057] Control system 112 may optionally further include a virtual visualization system to provide navigation assistance to operator O when controlling medical instrument system 104 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 112 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, including an optimal first location for performing treatment. The pre-operative plan may include, for example, a planned size to expand an expandable device, a treatment duration, a treatment temperature, and/or multiple deployment locations.

[0058] FIG. 2A is a simplified diagram of a medical instrument system 200 according to some embodiments. In some embodiments, medical instrument system 200 may be used in an image- guided medical procedure. In some examples, medical instrument system 200 may be used for non-teleoperational exploratory procedures or in procedures involving traditional manually operated medical instruments, such as endoscopy. [0059] Medical instrument system 200 includes elongate flexible device 202, such as a flexible catheter or endoscope, coupled to a drive unit 204. Elongate device 202 includes a flexible body 216 having proximal end 217 and distal end, or tip portion, 218. In some embodiments, flexible body 216 has an approximately 8-20 mm outer diameter. Other flexible body outer diameters may be larger or smaller. The entire length of flexible body 216, between distal end 218 and proximal end 217, may be effectively divided into segments 224.

[0060] Medical instrument system 200 optionally includes a tracking system 230 for determining the position, orientation, speed, velocity, pose, and/or shape of distal end 218 and/or of one or more segments 224 along flexible body 216 using one or more sensors and/or imaging devices. Tracking system 230 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 112 in Fig. 1.

[0061] Tracking system 230 may optionally track distal end 218 and/or one or more of the segments 224 using a shape sensor 222. In some embodiments, tracking system 230 may optionally and/or additionally track distal end 218 using a position sensor system 220, such as an electromagnetic (EM) sensor system. In some examples, position sensor system 220 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.

[0062] Flexible body 216 includes one or more channels 221 sized and shaped to receive one or more medical instruments 226. In some embodiments, flexible body 216 includes two channels 221 for separate instruments 226, however, a different number of channels 221 may be provided. FIG. 2B is a simplified diagram of flexible body 216 with medical instrument 226 extended according to some embodiments. In some embodiments, medical instrument 226 may be used for procedures such as surgery, biopsy, ablation, illumination, irrigation, or suction. Medical instrument 226 can be deployed through channel 221 of flexible body 216 and used at a target location within the anatomy. Medical instrument 226 may include, for example, image capture devices, biopsy instruments, ablation instruments, catheters, 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 226 may be advanced from the opening of channel 221 to perform the procedure and then retracted back into the channel when the procedure is complete. Medical instrument 226 may be removed from proximal end 217 of flexible body 216 or from another optional instrument port (not shown) along flexible body 216. The medical instrument 226 may be used with an image capture device (e.g., an endoscopic camera) also within the flexible steerable body 216. Alternatively, the medical instrument 226 may itself be the image capture device.

[0063] Medical instrument 226 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 226. Flexible body 216 may also house cables, linkages, or other steering controls (not shown) that extend between drive unit 204 and distal end 218 to controllably bend distal end 218 as shown, for example, by broken dashed line depictions 219 of distal end 218. In some examples, at least four cables are used to provide independent “up-down” steering to control a pitch motion of distal end 218 and “left-right” steering to control a yaw motion of distal end 218. In embodiments in which medical instrument system 200 is actuated by a robotically- assisted assembly, drive unit 204 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 200 may include gripping features, manual actuators, or other components for manually controlling the motion of medical instrument system 200. The information from tracking system 230 may be sent to a navigation system 232 where it is combined with information from visualization system 231 and/or the preoperatively obtained models to provide the physician or other operator with real-time position information.

[0064] Other configurations of teleoperated manipulator systems are also contemplated, such as systems configured for multi-port or single-port procedures. For example, the embodiments described herein may be used with a da Vinci® Surgical System, such as the da Vinci X®, Xi®, or SP® Surgical Systems, all commercialized by Intuitive Surgical, Inc., of Sunnyvale, California. [0065] FIG. 3 illustrates an example embodiment of a manipulator system 300 that may be used as part of the manipulator system 100. The manipulator system 300 includes a base 320, a main column 340, and a main boom 360 connected to main column 340. Manipulator system 300 also includes a plurality of manipulator arms 310, 31 1 , 312, 313, which are each connected to main boom 360. The manipulator arms 310, 311, 312, and 313, may be used as the manipulator assemblies 102. Manipulator arms 310, 311, 312, 313 each include an instrument mount portion 322 to which an instrument 330 may be mounted, which is illustrated as being attached to manipulator arm 310. While the manipulator system 300 depicts four manipulator arms, various embodiments may include more or fewer manipulator arms.

[0066] Instrument mount portion 322 may include a drive assembly 323 and a cannula mount 324, with a transmission mechanism 334 of the instrument 330 connecting with the drive assembly 323, according to an embodiment. Cannula mount 324 is configured to hold a cannula 336 through which a shaft 332 of instrument 330 may extend to a surgery site during a surgical procedure. Drive assembly 323 contains a variety of drive and other mechanisms that are controlled to respond to input commands at the operator input system 106 and transmit forces to the transmission mechanism 334 to actuate the instrument 330. Although the embodiment of FIG. 3 shows an instrument 330 attached to only manipulator arm 310 for ease of viewing, an instrument may be attached to any and each of manipulator arms 310, 311, 312, 313.

[0067] FIG. 4 illustrates an example embodiment of a manipulator system 400 that may be used as part of the manipulator system 100. In FIG. 4, a portion of a manipulator arm 440 of the manipulator system 400 is shown with two instruments 408, 410 in an installed position. The schematic illustration of FIG. 4 depicts only two instruments for simplicity, but more than two instruments may be mounted in an installed position at the manipulator system 400 as those having ordinary skill in the art are familiar. Each instrument 408, 410 includes a shaft 420, 430 having at a distal end a moveable end effector or an endoscope, camera, or other sensing device, and may or may not include a wrist mechanism (not shown) to control the movement of the distal end.

[0068] In the embodiment of FIG. 4, the distal end portions of the instruments 408, 410 are received through a single port structure 480 to be introduced into the patient. As shown, the port structure includes a cannula and an instrument entry guide inserted into the cannula. Individual instruments are inserted into the entry guide to reach a surgical site.

[0069] Transmission mechanisms 485, 490 are disposed at a proximal end portion of each shaft 420, 430 and connect through a sterile adaptor 450, 460 with drive assemblies 470, 475, which contain a variety of internal mechanisms (not shown) that are controlled by a controller (e.g., at a control cart of a surgical system) to respond to input commands at a surgeon side console of a surgical system to transmit forces to the force transmission mechanisms 485, 490 to actuate instruments 408, 410.

[0070] The manipulator systems described herein are not limited to the embodiments of FIGS. 1, 2, 3, and 4, and various other teleoperated, computer-assisted manipulator configurations may be used with the embodiments described herein. The diameter or diameters of an instrument shaft and end effector are generally selected according to the size of the cannula with which the instrument will be used and depending on the surgical procedures being performed.

[0071] FIGS. 5 and 6 are various views of a medical device 500, according to an embodiment. In some embodiments, the medical device 500 or any of the components therein are optionally parts of an instrument for a surgical system that performs surgical procedures, and which surgical system can include a manipulator unit, a series of kinematic linkages, a series of cannulas, or the like. The medical device 500 (and any of the instruments described herein) can be used in any suitable surgical system, such as the manipulator system 100 or the manipulator system 200 shown and described above. The medical device 500 may be used as the medical instruments 226, 330, 408, and 410 described above. As shown in FIG. 5, the medical device 500 defines (or is included within) a distal boundary (or footprint) 502 that corresponds to a cannula size, or a size to fit within a working channel of an elongate flexible device (such as a flexible catheter or endoscope), or other size dictated by the surgical environment. The distal boundary 502 can be a cylindrical shape having any suitable nominal diameter (e.g., 8 mm, 5 mm or any size therebetween). The medical device 500 includes a force transmission mechanism 504, a shaft 506, an optional distal wrist assembly 508, a distal end effector 510, and a set of tension elements 512 (which can be, for example, a cable, band, or the like).

[0072] The medical device 500 can include multiple tension elements 512. For example, in some embodiments, the medical device 500 can include two tension elements 512 with each tension element 512 having two segments extending along the shaft 506 of the instrument, thereby forming four proximal end portions. Referring to FIG. 6, respective tension elements 512 may be routed through a wrist assembly 514 and wrapped about respective pulleys 516 or 517 of the tool members 518, 519. Each tension element 512 has two tension element segments along the shaft 506 with two proximal end portions that, when moved in opposite directions, can (among other things) cause rotation of the respective tool member 518 or 519 about the axis Al. This arrangement can be referred to as a “four cable” wrist and changing the pitch, yaw, or grip of the medical device 500 can be performed by manipulating the four proximal end portions of the tension elements 512 in a manner similar to that shown and described in U.S. Patent Publication No. 2020/0390430 incorporated herein by reference above. In other embodiments, the medical device 500 can include four separate tension elements 512 with two separate tension elements coupled to the pulley 516 of the tool member 518 and two separate tension elements coupled to the pulley 517 of the tool member 518, thereby creating four proximal tension element end portions. In some embodiments, the medical device 500 can include more than two or four tension elements 512 and more than four proximal tension element end portions. The tension elements 512 can be, for example, cables, bands, or the like that couple the force transmission mechanism 504 to the distal wrist assembly 508 and end effector 510. In some embodiments, the tension elements 512 can be constructed from a polymer.

[0073] The medical device 500 is configured such that movement of one or more of the tension elements 512 produces rotation of the end effector 510 about a first rotation axis Al (see FIG. 6, which functions as a yaw axis, the term yaw is arbitrary), rotation of the wrist assembly 508 about a second rotation axis A2 and/or optionally about a third rotation axis A3 (which functions as a pitch axis, the term pitch is arbitrary), a cutting rotation of the tool members of the end effector 510 about the first rotation axis Al, or any combination of these movements. Changing the pitch or yaw of the medical device 500 can be performed by manipulating the tension elements 512 in a similar’ manner as that described with reference to the device 2400 described in copending International Patent Application Serial No. PCT/US2022/039942, entitled “Surgical Instrument Cable Control and Routing Structures,” the disclosure of which is incorporated herein by reference in its entirety.

[0074] As shown in FIG. 5, the proximal force transmission mechanism 504 includes a set of drive components such as capstans 522 and 524 that rotate or “wind” a proximal portion of any of the tension elements 512 to produce the desired tension element movement. In some embodiments, two proximal ends of a tension element 512, which are associated with opposing directions of a single degree of freedom, are connected to two independent drive capstans 522 and 524. This arrangement, which is generally referred to as an antagonist drive system, allows for independent control of the movement of (e.g., pulling in or paying out) each of the ends of the tension elements 512. The force transmission mechanism 504 produces movement of the tension elements 512, which operates to produce the desired articulation movements (pitch, yaw, or grip) at the wrist assembly 508 and end effector 510. Accordingly, the force transmission mechanism 504 includes components to move a first proximal end portion of the tension clement 512 via the first capstan 522 in a first direction (e.g., a proximal direction) and to move a second proximal end portion of the tension element 512 via the second capstan 524 in a second opposite direction (e.g., a distal direction). The force transmission mechanism 504 can also move both proximal end portions of the tension element 512 in the same direction. In this manner, the force transmission mechanism 504 can maintain the desired tension within the tension elements 512.

[0075] In some embodiments, the force transmission mechanism 504 can include any of the assemblies or components described in International Patent Application Serial No. PCT/US2022/039942, entitled “Surgical Instrument Cable Control and Routing Structures,” the disclosure of which is incorporated herein by reference in its entirety. In other embodiments, however, any of the medical devices described herein can have the two ends of a tension elements wrapped about a single capstan. This alternative arrangement, which is generally referred to as a self-antagonist drive system, operates the two ends of the tension element using a single drive motor.

[0076] Moreover, although the force transmission mechanism 504 is shown as including capstans, in other embodiments, a force transmission mechanism can include one or more linear actuators that produce translation (linear motion) of a portion of the cables. Such force transmission mechanisms can include, for example, a gimbal, a lever, or any other suitable mechanism to directly pull (or release) an end portion of any of the cables. For example, in some embodiments, the proximal force transmission mechanism 504 can include any of the proximal force transmission mechanisms or components described in U.S. Patent Application Pub. No. US 2015/0047454 Al (filed Aug. 15, 2014), entitled “Lever Actuated Gimbal Plate,” or U.S. Patent No. US 6,817,974 B2 (filed Jun. 28, 2001), entitled “Surgical Tool Having Positively Positionable Tendon-Actuated Multi-Disk Wrist Joint,” each of which is incorporated herein by reference in its entirety.

[0077] The shaft 506 can be any suitable elongated shaft that is coupled to the force transmission mechanism 504 and to the optional wrist assembly 508 (when present) or the end effector 510. Specifically, the shaft 506 includes a proximal portion 526 that is coupled to the force transmission mechanism 504, and a distal portion 528 that is coupled to the optional wrist assembly 508 or to the end effector 510. The shaft 506 defines a passageway or series of passageways through which the tension elements 512 and other components (e.g., electrical wires, ground wires, or the like) can be routed from the force transmission mechanism 504 to the wrist assembly 508. In some embodiments, the shaft 506 may be a substantially rigid member, while in other embodiments, the shaft 506 may be a flexible member.

[0078] FIG. 7 is a side view of a plurality of miniature capstans 600 for use in a medical instrument or instrument system, such as medical instrument system 104, medical instrument system 200, medical instruments 330, 408, and 410, and medical device 500. The medical device may be a surgical instrument, may optionally include a wrist mechanism (such as distal wrist assembly 508) that is actuated by the capstans 600 and configured for bidirectional motion along four axes, or may be an elongate flexible device (such as an endoscope).

[0079] Implementation of the one or more capstans 600 is discussed herein specifically with respect to medical device 500, but the one or more capstans 600 could be used with any number of medical devices including those previously discussed. The medical device 500 disclosed above, while suitable for many applications, may have decreased performance within an extended tortuous path such as the GI system for the reasons described in the background section above. Specifically, the set of tension elements 512 may generate too much capstan friction when the capstans 522, 524 are rotated to linearly move the tension elements 512 in the flexible medical device. By utilizing the plurality of miniature capstans 600 (which are distally spaced from force transmission mechanism 504, unlike capstans 522 and 524) along with implementing the changes described herein, the medical device 500 can be used reliably even when the medical device has a flexible shaft (e.g., shaft 506) with a length of one meter or more and is routed through highly tortuous anatomy.

[0080] The one or more capstans 600 shown in FIG. 7 are each coupled to one of one or more elongate rotatable drive elements 601 at a first end 604 of each of the one or more capstans 600. The elongate rotatable drive elements 601 are respectively coupled to rotatable inputs 605 of a proximal force transmission member 603 that is configured to receive forces or torques from an external device 607. The external device 607 may be outputs from a manipulator assembly of a robotically-assisted manipulator system such as described above. The elongate rotatable drive elements 601 may be housed within an elongate shaft 609, comparable to shaft 506 of FIG. 5, that has a proximal end 611 coupled to the proximal force transmission member 603. The one or more capstans 600 are coupled to the distal end 613 of the elongate shaft 609. As a result, each of the one or more capstans 600 is distally spaced from the force transmission member 603 via the elongate shaft 609. The elongate shaft 609 may be rigid or may be flexible. In some arrangements, the elongate shaft 609 may have a length greater than or equal to one meter to enable, for example, use in procedures in the gastrointestinal tract.

[0081] As shown in FIG. 7, each of the one or more tension elements 602 has a first end 604 coupled to one of the one or more capstans 600 and a second end 608 directly coupled to a distal end portion 610 of the medical device (such as medical device 500). Specifically, in FIG. 7, each of the one or more tension elements 602 is coupled to the distal end portion 610 of a medical device that includes a coil pipe bending section 612, an elbow mechanism 614, and a wrist mechanism 616. The wrist mechanism 616 and/or the elbow mechanism 614 may be actuated by the one or more tension elements 602. For example, the wrist mechanism 616 may be actuated by the one or more tension elements 602 for bidirectional motion along four axes. The medical device may be a surgical instrument. The distal end portion 610 of the medical device may be an end effector actuated by the one or more tension elements 602. Further, the distal end portion 610 may be actuated manually when the medical device is decoupled from the external device, for example in the event of a power outage.

[0082] A length 618 of each of the one or more tension elements 602 is configured to wrap around one of the one or more capstans 600, and (as best shown in FIG. 11) specifically around a capstan shaft 619 of each of the one or more capstans 600. As the length 618 of a tension element 602 is wrapped around the capstan shaft 619, the second end 608 of the tension element 602 exerts an axial force on the distal end portion 610 of the medical device. Each capstan shaft 619 has a capstan diameter De (shown in FIG. 10), and the length 618 of each tension element 602 has a tension element diameter Dte (shown in FIG. 11). The ratio of the capstan diameter De to the tension element diameter Dte is less than 10:1, which illustrates the miniature size of the one or more capstans 600 given that traditional capstans such as capstans 522 and 524 typically have a ratio as large as 400:1 (e.g., when considering an individual cable) or 20:1 to 40:1 (e.g., for a bundle of braided cables). In order to bend around the miniature size of the one or more capstans 600 and to reduce friction, the one or more tension elements 602 may comprise a braided polymer, such as high density polyethylene (HDPE), PBO, or Vectran. The capstan shaft 619 may comprise stainless steel. To reduce the coefficient of friction, the one or more tension elements 602 may be lubricated. [0083] Turning to FIGS. 8 and 9, the one or more capstans 600 are configured to connect to a proximal bulkhead 620 and a distal bulkhead 622. As shown in FIG. 8, the proximal bulkhead 620 includes a rotary bearing 624 for each of the one or more capstans 600. The first end 604 of each of the one or more capstans 600 can be positioned within a respective rotary bearing 624. As shown in FIG. 8, the distal bulkhead 622 includes a capstan pocket 626 for each of the one or more capstans 600 and a redirect aperture 628 adjacent each capstan pocket 626 for each of the one or more tension elements 602. As shown in FIG. 9, the redirect aperture 628 is configured to redirect a respective tension element 602 of the one or more tension elements 602 from a wrap angle W relative to a longitudinal axis L to an axial angle A substantially parallel to the longitudinal axis L (as shown in FIG. 9). The transition from the wrap angle W to the axial angle A may be approximately 90 degrees. To facilitate this transition, as shown in FIG. 8, the redirect aperture 628 adjacent each capstan pocket 626 includes a shoulder 630 having a smooth surface.

[0084] Turning to FIGS. 10 and 11, each of the one or more capstans 600 may have a second end 632 including a conical section 634 having a spherical domed tip 636 as shown in FIG. 11. The spherical domed tip 636 bears on the bottom of the capstan pocket 626 in the distal bulkhead 622, creating a low cost, low friction rotary bearing. The proximal bulkhead 620 and/or the distal bulkhead 622 may comprise machined or molded Acetal plastic or Carbon-filled PEEK to minimize friction. Each of the one or more capstans 600 may further include a connection feature 633, such as a recessed area or apertures, to which a tension element 602 can be secured by physical engagement, adhesive, and/or heat. The connection feature may have a plurality of apertures or other guide features forming a high friction path for the tension element 602 that resists movement of the tension element 602 relative to the connection feature. The tension element 602, when routed around the high friction path, retains the tension element 602 into connection with the connection feature and thereby the capstan 600.

[0085] In the arrangement shown in FIGS. 10 and 11, the capstan shaft 619 has a constant capstan diameter De (illustrated in FIG. 10). A tension element 602 is configured to slide axially down the capstan shaft 619 while being wrapped around the capstan shaft 619 when the capstan shaft 619 is rotated. As shown in FIG. 10, the length 618 of the tension element 602 that is wrapped around the capstan shaft 619 has a tension element diameter Dte. An effective gear ratio is the amount of wrap or unwrap of the tension element 602 onto or off the capstan shaft 619 per revolution of the capstan shaft 619. When the capstan shaft 619 has a constant capstan diameter De, the effective gear ratio will typically be constant because one revolution of the capstan shaft 619 will cause a consistent amount of wrap or unwrap of the tension element 602. However, at the start of wrapping, the effective gear ratio may change because the amount of wrap or unwrap of the tension element 602 per revolution may be nonlinear due to a changing wrap angle W (discussed above and illustrated in FIG. 9). Pre-winding the tension element 602 around the capstan shaft 619 until a substantially constant wrap angle W is achieved ensures an approximately constant effective gear ratio (e.g., an effective gear ratio that is fixed and/or varies by no more than 20% from a baseline effective gear ratio).

[0086] In other arrangements, at least one of the one or more capstans 600 may have a capstan shaft 619 with a cross-section that changes along the longitudinal axis L such that the effective gear ratio changes as a tension element 602 is wrapped around the capstan shaft 619 because the amount of wrap or unwrap of the tension element 602 around the capstan shaft 619 will depend on the capstan diameter De of the changing cross-section . This may be beneficial to adjust the force provided to the distal end portion 610 of the medical device based on operation of the medical device. For example, the medical device may be an endoscope and the change in the cross-section of the capstans 600 may correspond with a change in a bend angle of the endoscope. The change in the cross-section adjusts the effective gear ratio to offset an increase in friction resulting from the change in the bend angle of the endoscope.

[0087] FIG. 12 illustrates schematically a method 700 of preparing a medical device with distally spaced capstans by pre-winding tension elements around the capstans. At box 702, the method 700 includes providing a medical device (such as medical device 500) comprising a proximal force transmission member 603, one or more elongate rotatable drive elements 601 coupled to the proximal force transmission member 603, one or more capstans 600 distally spaced from the force transmission member 603 and each respectively coupled to one of the one or more elongate rotatable drive elements 601, and one or more tension elements 602, each of the one or more tension elements 602 coupled to one of the one or more capstans 600 and to a distal end portion 610 of the medical device. At box 704, the method 700 includes actuating the proximal force transmission member 603 to rotate the one or more elongate rotatable drive elements 601 and the one or more capstans 600. At box 706, the method 700 includes wrapping the one or more tension elements 602 around the one or more capstans 600 until the one or more tension elements 602 have an approximately constant effective gear ratio for subsequent wrapping. [0088] FIG. 13 illustrates schematically a method 800 of using a medical device having capstans distally spaced from a proximal force transmission member. At box 802, the method 800 includes providing a medical device (such as medical device 500) comprising a proximal force transmission member 603, one or more elongate rotatable drive elements 601 coupled to the proximal force transmission member 603, one or more capstans 600 distally spaced from the force transmission member 603 and each respectively coupled to one of the one or more elongate rotatable drive elements 601, and one or more tension elements 602, each of the one or more tension elements 602 coupled to one of the one or more capstans 600 and to a distal end portion 610 of the medical device. At box 804, the method 800 includes actuating the proximal force transmission member 603 to rotate the one or more elongate rotatable drive elements 601 and the one or more capstans 600. At box 806, the method 800 includes wrapping the one or more tension elements 602 around the one or more capstans 600 to operate a distal end portion 610 of the medical device. At box 808, the method 800 includes changing an effective gear ratio to correspond with a change in a force needed to operate the distal end portion 610 of the medical device.

[0089] In the description, specific details have been set forth describing some examples. Numerous specific details are set forth in order 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 of 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.

[0090] Elements described in detail with reference to one example, 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 foregoing description, one or more elements shown and described in association with one example, implementation, or application may be incorporated into other examples, implementations, or application 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. Similarly, it should be understood that any particular element, including a system component or a method process, is optional and is not considered to be an essential feature of the present disclosure unless expressly stated otherwise.

[0091] 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 particular, it is fully contemplated that the features, components, and/or steps described with respect to one example may be combined with the features, components, and/or steps described with respect to other examples of the present disclosure. 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.

[0092] While some examples are provided herein in the context of 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 may also be used for surgical and nonsurgical medical treatment or diagnosis procedures.

[0093] The methods described herein are illustrated as a set of operations or processes. Not all the illustrated processes may be performed in all examples of the methods. Additionally, one or more processes that are not expressly illustrated or described may be included before, after, in between, or as part of the example processes. In some examples, one or more of the processes may be performed by the control system (e.g., control system 112) 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 (e.g., processors of control system 112) may cause the one or more processors to perform one or more of the processes.

[0094] 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 the present disclosure are essentially the code segments to perform the necessary 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 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 one example, the control system supports wireless communication protocols such as Bluetooth, IrDA, HomeRF, IEEE 802.11, DECT, and Wireless Telemetry.

[0095] Note that the processes and displays presented may 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 present disclosure 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 present disclosure.

[0096] 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 (three degrees of rotational freedom - e.g., roll, pitch, and yaw). The “pitch” direction and “yaw” direction are not necessarily limited to vertical and horizontal movement, respectively, but rather may be arbitrary directions orthogonal to one another. 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 (up to six total degrees of freedom). As used herein, the term “shape” refers to a set of poses, positions, or orientations measured along a length of an object. As used herein, the term “about” when used in connection with a referenced numeric indication means the referenced numeric indication plus or minus up to 10 percent of that referenced numeric indication. For example, the language “about 50” covers the range of 45 to 55. Similarly, the language “about 5” covers the range of 4.5 to 5.5.

[0097] As used in this specification and the appended claims, the word “distal” refers to direction towards a work site, and the word “proximal” refers to a direction away from the work site. Thus, for example, the end of a medical device that is closest to the target tissue would be the distal end of the medical device, and the end opposite the distal end would be the proximal end of the medical device.

[0098] Further, specific words chosen to describe one or more embodiments and optional elements or features are not intended to limit the invention. For example, spatially relative terms — such as “beneath”, “below”, “lower”, “above”, “upper”, “proximal”, “distal”, and the like — may be used to describe the relationship of one element or feature to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., translational placements) and orientations (i.e., rotational placements) of a device in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. Thus, the term “below” can encompass both positions and orientations of above and below. A device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Likewise, descriptions of movement along (translation) and around (rotation) various axes include various spatial positions and orientations. The combination of a body’s position and orientation defines the body’s pose.

[0099] Similarly, geometric terms, such as “parallel”, “perpendicular”, “round”, or “square”, are not intended to require absolute mathematical precision, unless the context indicates otherwise. Instead, such geometric terms allow for variations due to manufacturing or equivalent functions. For example, if an element is described as “round” or “generally round,” a component that is not precisely circular (e.g., one that is slightly oblong or is a many-sided polygon) is still encompassed by this description.

[0100] In addition, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. The terms “comprises”, “includes”, “has”, and the like specify the presence of stated features, steps, operations, elements, components, etc. but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, or groups.

[0101] Unless indicated otherwise, the terms apparatus, medical device, medical instrument, and variants thereof, can be interchangeably used.

[0102] While certain exemplary examples of the present disclosure 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 disclosure herein, and that the examples of the present disclosure should not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the ail.

Claims

What is claimed is:

1. A medical device comprising: a proximal force transmission member including one or more rotatable inputs configured to receive forces or torques from an external device; an elongate shaft having a proximal end coupled to the proximal force transmission member, the elongate shaft housing one or more elongate rotatable drive elements respectively coupled to one of the one or more rotatable inputs of the proximal force transmission member; one or more capstans coupled to a distal end of the elongate shaft, the one or more capstans each comprising a first end respectively coupled to one of the one or more elongate rotatable drive elements, each of the one or more capstans being distally spaced from the proximal force transmission member via the elongate shaft; and one or more tension elements, each of the one or more tension elements respectively coupled to one of the one or more capstans and to a distal end of the medical device.

2. The medical device of claim 1, wherein the one or more elongate rotatable drive elements are a plurality of elongate rotatable drive elements, the one or more capstans are a plurality of capstans, and the one or more tension elements are a plurality of tension elements.

3. The medical device of claim 1, wherein each of the one or more capstans includes a shaft, and wherein each of the one or more tension elements is configured to slide axially down the shaft of the one of the one or more capstans while being wrapped around the one of the one or more capstans.

4. The medical device of claim 1, wherein each of the one or more tension elements comprises a braided polymer.

5. The medical device of claim 1, wherein each of the one or more tension elements are lubricated.

6. The medical device of claim 1, wherein the elongate shaft is flexible.

7. The medical device of claim 1 , wherein the elongate shaft is rigid.

8. The medical device of any one of claims 1 to 7, wherein each of the one or more tension elements is pre-wound around the one of the one or more capstans to have an approximately constant effective gear ratio for subsequent wrapping.

9. The medical device of any one of claims 1 to 7, wherein at least one of the one or more capstans has a shaft with a cross-section that changes along a longitudinal axis such that an effective gear ratio changes as one of the one or more tension elements is wrapped around the shaft of the at least one of the one or more capstans.

10. The medical device of claim 9, wherein the medical device is an endoscope and the change in the cross-section corresponds with a change in a bend angle of the endoscope.

11. The medical device of claim 10, wherein the change in the cross-section adjusts an effective gear ratio to offset an increase in friction resulting from the change in the bend angle of the endoscope.

12. The medical device of any one of claims 1 to 7, wherein the distal end of the medical device can be actuated manually when the medical device is decoupled from the external device.

13. The medical device of any one of claims 1 to 7, wherein the one or more capstans are arranged in antagonistic pairs.

14. The medical device of any one of claims 1 to 7, wherein the elongate shaft has a length greater than or equal to one meter.

15. The medical device of any one of claims 1 to 7, further comprising a distal bulkhead coupled to the one or more capstans, the distal bulkhead including one or more capstan pockets to receive a respective capstan of the one or more capstans and a redirect aperture adjacent each capstan pocket for each of the one or more tension elements.

16. The medical device of claim 15, wherein the redirect aperture adjacent each capstan pocket is configured to redirect one of the one or more tension elements from a wrap angle relative to a longitudinal axis of the capstan to an axial angle substantially parallel to the longitudinal axis of the capstan.

17. The medical device of claim 16, wherein the redirect aperture adjacent each capstan pocket includes a shoulder having a smooth surface.

18. The medical device of any one of claims 1 to 7, each of the one or more capstans having a second end including a conical section having a spherical domed tip.

19. The medical device of any one of claims 1 to 7, further comprising a proximal bulkhead coupled to the one or more capstans, the proximal bulkhead including a rotary bearing for each of the one or more capstans.

20. The medical device of claim 19, wherein the first end of each of the one or more capstans is positioned within a respective rotary bearing of the proximal bulkhead.

21. The medical device of any one of claims 1 to 7, wherein the medical device is a surgical instrument.

22. The medical device of claim 21, wherein the distal end of the medical device is an end effector actuated by the one or more tension elements.

23. The medical device of any one of claims 1 to 7, wherein the medical device includes a wrist mechanism and an end effector distal to the wrist mechanism, the wrist mechanism configured to be actuated by the one or more tension elements and configured for bidirectional motion along four axes.

24. The medical device of claim 23, wherein the medical device further includes an elbow mechanism and an end effector distal to the elbow mechanism, the elbow mechanism configured for bidirectional motional along four axes.

25. A medical device comprising: a proximal force transmission member including one or more rotatable inputs configured to receive forces or torques from an external device; an elongate shaft having a proximal end coupled to the proximal force transmission member, the elongate shaft housing one or more elongate rotatable drive elements respectively coupled to one of the one or more rotatable inputs of the proximal force transmission member; one or more capstans coupled to a distal end of the elongate shaft, the one or more capstans each comprising a first end respectively coupled to one of the elongate rotatable drive elements; and one or more tension elements, each of the one or more tension elements having a first end coupled to one of the one or more capstans, a second end directly coupled to a distal end of the medical device, and a length configured to wrap around the one of the one or more capstans, the second end of each of the one or more tension elements configured to exert an axial force on the distal end of the medical device as the length of the respective tension element is wrapped around the one of the one or more capstans.

26. The medical device of claim 25, wherein the one or more elongate rotatable drive elements are a plurality of elongate rotatable drive elements, the one or more capstans arc a plurality of capstans, and the one or more tension elements are a plurality of tension elements.

27. The medical device of claim 25, wherein each of the one or more capstans includes a shaft, and wherein each of the one or more tension elements is configured to slide axially down the shaft of the one of the one or more capstans while being wrapped around the one of the one or more capstans.

28. The medical device of claim 25, wherein the one or more tension elements comprises braided polymer.

29. The medical device of claim 25, wherein the one or more tension elements are lubricated.

30. The medical device of claim 25, wherein the elongate shaft is flexible.

31. The medical device of claim 25, wherein the elongate shaft is rigid.

32. The medical device of any one of claims 25 to 31, wherein each of the one or more tension elements is pre-wound around the one of the one or more capstans to have an approximately constant effective gear ratio for subsequent wrapping.

33. The medical device of any one of claims 25 to 31, wherein at least one of the one or more capstans has a shaft with a cross-section that changes along a longitudinal axis such that a effective gear ratio changes as one of the one or more tension elements is wrapped around the shaft of the at least one of the one or more capstans.

34. The medical device of claim 33, wherein the medical device is an endoscope and the change in the cross-section corresponds with a change in a bend angle of the endoscope.

35. The medical device of claim 34, wherein the change in the cross-section adjusts a effective gear ratio to offset an increase in friction resulting from the change in the bend angle of the endoscope.

36. The medical device of any one of claims 25 to 31, wherein the distal end of the medical device can be actuated manually when the medical device is decoupled from the external device.

37. The medical device of any one of claims 25 to 31, wherein the one or more capstans are arranged in antagonistic pairs.

38. The medical device of any one of claims 25 to 31, wherein the elongate shaft has a length greater than or equal to one meter.

39. The medical device of any one of claims 25 to 31 , further comprising a distal bulkhead coupled to the one or more capstans, the distal bulkhead including one or more capstan pockets to each receive a respective capstan of the one or more capstans and a redirect aperture adjacent each capstan pocket for each of the one or more tension elements.

40. The medical device of claim 39, wherein the redirect aperture adjacent each capstan pocket is configured to redirect one of the one or more tension elements from a wrap angle relative to a longitudinal axis of the capstan to an axial angle substantially parallel to the longitudinal axis of the capstan.

41. The medical device of claim 40, wherein the redirect aperture adjacent each capstan pocket includes a shoulder having a smooth surface.

42. The medical device of any one of claims 25 to 31, each of the one or more capstans having a second end including a conical section having a spherical domed tip.

43. The medical device of any one of claims 25 to 31, further comprising a proximal bulkhead coupled to the one or more capstans, the proximal bulkhead including a rotary bearing for each of the one or more capstans.

44. The medical device of claim 43, wherein the first end of each of the one or more capstans is positioned within a respective rotary bearing of the proximal bulkhead.

45. The medical device of any one of claims 25 to 31, wherein the medical device is a surgical instrument.

46. The medical device of claim 45, wherein the distal end of the medical device is an end effector actuated by the one or more tension elements.

47. The medical device of any one of claims 25 to 31, wherein the medical device includes a wrist mechanism and an end effector distal to the wrist mechanism, the wrist mechanism configured to be actuated by the one or more tension elements and configured for bidirectional motion along four axes.

48. The medical device of claim 47, wherein the medical device further includes an elbow mechanism and an end effector distal to the elbow mechanism, the elbow mechanism configured for bidirectional motional along four axes.

49. A medical device comprising: a proximal force transmission member including one or more rotatable inputs configured to receive forces or torques from an external device; an elongate shaft having a proximal end coupled to the proximal force transmission member, the elongate shaft housing one or more elongate rotatable drive elements respectively coupled to the one or more rotatable inputs of the proximal force transmission member; and one or more capstans coupled to a distal end of the elongate shaft, the one or more capstans each comprising a first end respectively coupled to the elongate rotatable drive elements and a capstan shaft having a capstan diameter; one or more tension elements, each of the one or more tension elements having a first end coupled to one of the one or more capstans, a second end coupled to a distal end of the medical device, and a tension element diameter; wherein a ratio of the capstan diameter to the tension element diameter is less than 10:1.

50. The medical device of claim 49, wherein the one or more elongate rotatable drive elements are a plurality of elongate rotatable drive elements, the one or more capstans are a plurality of capstans, and the one or more tension elements are a plurality of tension elements.

51. The medical device of claim 49, wherein each of the one or more capstans includes a shaft, and wherein each of the one or more tension elements is configured to slide axially down the shaft of the one of the one or more capstans while being wrapped around the one of the one or more capstans.

52. The medical device of claim 49, wherein the one or more tension elements comprises braided polymer.

53. The medical device of claim 49, wherein the one or more tension elements are lubricated.

54. The medical device of claim 49, wherein the elongate shaft is flexible.

55. The medical device of claim 49, wherein the elongate shaft is rigid.

56. The medical device of any one of claims 49 to 55, wherein each of the one or more tension elements is pre-wound around the one of the one or more capstans to have a approximately constant effective gear ratio for subsequent wrapping.

57. The medical device of any one of claims 49 to 55, wherein at least one of the one or more capstans has a shaft with a cross-section that changes along a longitudinal axis such that a effective gear ratio changes as one of the one or more tension elements is wrapped around the shaft of the at least one of the one or more capstans.

58. The medical device of claim 57, wherein the medical device is an endoscope and the change in the cross-section corresponds with a change in a bend angle of the endoscope.

59. The medical device of claim 58, wherein the change in the cross-section adjusts a effective gear ratio to offset an increase in friction resulting from the change in the bend angle of the endoscope.

60. The medical device of any one of claims 49 to 55, wherein the distal end can be actuated manually when the medical device is decoupled from the external device.

61. The medical device of any one of claims 49 to 55, wherein the one or more capstans are arranged in antagonistic pairs.

62. The medical device of any one of claims 49 to 55, wherein the elongate shaft has a length greater than or equal to one meter.

63. The medical device of any one of claims 49 to 55, further comprising a distal bulkhead coupled to the one or more capstans, the distal bulkhead including one or more capstan pockets to each receive a respective capstan of the one or more capstans and a redirect aperture adjacent each capstan pocket for each of the one or more tension elements.

64. The medical device of claim 63, wherein the redirect aperture adjacent each capstan pocket is configured to redirect one of the one or more tension elements from a wrap angle relative to a longitudinal axis of the capstan to an axial angle substantially parallel to the longitudinal axis of the capstan.

65. The medical device of claim 64, wherein the redirect aperture adjacent each capstan pocket includes a shoulder having a smooth surface.

66. The medical device of any one of claims 49 to 55, each of the one or more capstans having a second end including a conical section having a spherical domed tip.

67. The medical device of any one of claims 49 to 55, further comprising a proximal bulkhead coupled to the one or more capstans, the proximal bulkhead including a rotary bearing for each of the one or more capstans.

68. The medical device of claim 67, wherein the first end of each of the one or more capstans is positioned within a respective rotary bearing of the proximal bulkhead.

69. The medical device of any one of claims 49 to 55, wherein the medical device is a surgical instrument.

70. The medical device of claim 69, wherein the distal end of the medical device is an end effector actuated by the one or more tension elements.

71 . The medical device of any one of claims 49 to 55, wherein the medical device includes a wrist mechanism and an end effector distal to the wrist mechanism, the wrist mechanism configured to be actuated by the one or more tension elements and configured for bidirectional motion along four axes.

72. The medical device of claim 71, wherein the medical device further includes an elbow mechanism and an end effector distal to the elbow mechanism, the elbow mechanism configured for bidirectional motion along four axes.