System for applying preload tension to surgical instrument and related methods

Abstract

Systems and related methods of applying a preload tension for a surgical instrument are disclosed. A surgical system includes a dynamic preload tension feature for a tensioning element that actuates a distal component of a surgical instrument. The surgical instrument includes a chassis at a proximal end of the surgical instrument, a drive component mounted in the chassis, a distal component at a distal end of the surgical instrument, a flexible tensioning element coupled between a first of the drive components and the distal component, and a dynamic preload tensioner mounted in the chassis and coupled to a second of the drive components. The flexible tensioning element extends along a path. The dynamic preload tensioner is configured to be driven by the second of the drive components to move relative to the chassis and is positioned to change the path of the flexible tensioning element as the dynamic preload tensioner moves relative to the chassis.

Description

[0001] This application is a continuation of China Patent Application No. 201780063196.0 (PCT / US2017 / 056506), filed October 13, 2017, entered into the National Stage on April 12, 2019, entitled "Systems and Related Methods for Applying Pre-Load Tension for Surgical Instruments."

[0002] Cross Reference to Related Applications

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 408,242, filed October 14, 2016. The disclosure of the priority application is considered part of and is incorporated by reference into the disclosure of this application. TECHNICAL FIELD

[0004] This specification relates to systems and methods for applying pre-load tension for surgical instruments, particularly flexible tensioning elements for surgical instruments. BACKGROUND

[0005] In some cases, slack or low tension in cables of a surgical instrument can cause wobbling or unpredictable motion of an end effector of the surgical instrument. One way to ensure that there is sufficient cable tension throughout the design life of the surgical instrument is to pre-load the cable with a sufficiently high tension to resist some pre-loaded cable tension reduction, particularly when the end effector can be used for push-pull, clamping, clenching, or other actions that encounter resistance. However, the tension pre-load in the cable can increase the force that a drive system must exert to operate the surgical instrument. The pre-load can increase the friction of the cable traveling along the surface of the surgical instrument. The pre-load can also cause friction in the curved surfaces where the cable contacts openings through which the cable passes. SUMMARY

[0006] In one aspect, a computer-assisted surgical system includes a surgical instrument. The surgical instrument includes a chassis at a proximal end of the surgical instrument, drive components mounted in the chassis, a distal component at a distal end of the surgical instrument, a flexible tensioning element coupled between a first one of the drive components and the distal component, and a dynamic pre-load tensioner mounted in the chassis and coupled to a second one of the drive components. The flexible tensioning element extends along a path. The dynamic pre-load tensioner is configured to be driven by the second one of the drive components to move relative to the chassis and is positioned to change the path of the flexible tensioning element as the dynamic pre-load tensioner moves relative to the chassis.

[0007] In another aspect, a method includes moving a dynamic preload tensioner of a surgical instrument to increase tension in a flexible tensioning element of the surgical instrument. The method also includes driving the flexible tensioning element of the surgical instrument to move a distal component of the surgical instrument while maintaining a position of the dynamic preload tensioner.

[0008] In some embodiments, the system includes a manipulator on which the surgical instrument is mounted. The manipulator includes, for example, a first drive output positioned to drive a first drive component of the surgical instrument and a second drive output positioned to drive a second drive component of the surgical instrument.

[0009] In some embodiments, the system further includes a memory and a computer processor configured to execute instructions stored in the memory to perform the operations.

[0010] The operation includes, for example, driving a second drive component in the drive component to move the dynamic preload tensioner from a first position to a second position. The method includes, for example, moving the dynamic preload tensioner includes driving the first drive component in the drive component to move the dynamic preload tensioner from a first position to a second position. In some cases, the second drive component in the drive component is driven when the processor receives information indicating that the instrument is mounted to the manipulator. In some cases, the operation also includes driving the second drive component in the drive component until the processor receives information indicating that a predefined tension in the flexible tensioning element is achieved. The method includes, for example, driving the second drive component in the drive component after receiving information indicating that a predefined tension in the flexible tensioning element is achieved. In some cases, the information indicating the predefined tension in the flexible tensioning element is based on a torque of an actuator driving the second drive output.

[0011] In some embodiments, operations and / or methods include maintaining a position of a dynamic preload tensioner in response to determining that tension in the flexible tensioning element has reached a predefined tension. Operations and / or methods include, for example, detecting tension in the flexible tensioning element while moving the dynamic preload tensioner. Maintaining the position of the dynamic preload tensioner includes, for example, maintaining the position of the dynamic preload tensioner in response to the detected tension reaching the predefined tension. In some cases, moving the dynamic preload tensioner includes operating an actuator to cause the dynamic preload tensioner to move. Detecting tension in the flexible tensioning element includes, for example, detecting a torque applied by the actuator.

[0012] In some embodiments, moving the dynamic preload tensioner includes operating a second drive component among a plurality of drive components of the surgical instrument. The methods and / or operations further include, for example, operating a first drive component among the drive components to drive the flexible tensioning element to move the distal end member of the surgical instrument. In some cases, operating the first drive component among the drive components to drive the flexible tensioning element includes operating the first drive component among the drive components while maintaining a position of the dynamic preload tensioner.

[0013] In some embodiments, moving the dynamic preload tensioner includes moving the dynamic preload tensioner from a first position, wherein a first tension exists in the flexible tensioning element, to a second position, wherein a second tension exists in the flexible tensioning element. In some embodiments, in the first position of the dynamic preload tensioner, the first tension exists in the flexible tensioning element. In the second position of the dynamic preload tensioner, for example, the second tension exists in the flexible tensioning element. The second tension, for example, is greater than the first tension. In some cases, the first tension is zero.

[0014] In some embodiments, moving the dynamic preload tensioner includes moving the dynamic preload tensioner such that an adjustable preload is applied to the flexible tensioning element. In some embodiments, the dynamic preload tensioner is positioned such that the adjustable preload is applied to the flexible tensioning element when the dynamic preload tensioner is moved relative to the chassis.

[0015] In some embodiments, moving the dynamic preload tensioner includes moving the dynamic preload tensioner to change a path of each of a plurality of flexible tensioning elements of the surgical instrument. In some embodiments, the system includes a plurality of flexible tensioning elements, each coupled to a drive component mounted in a chassis. The dynamic preload tensioner is movable relative to the chassis, for example, to change the path of each of the plurality of flexible tensioning elements.

[0016] In some embodiments, the flexible tensioning element is formed from a polymer material.

[0017] In some embodiments, the dynamic preload tensioner includes an axially movable tensioning drum such that the tensioning drum engages a flexible tensioning element when the tensioning drum rotates. In some embodiments, moving the dynamic preload tensioner includes rotating the tensioning drum to cause the tensioning drum to move axially to engage the flexible tensioning element. In some cases, the dynamic preload tensioner includes a tensioning gear mounted to a base frame and rotatable along a ramp. In some cases, the ramp is defined by the base frame. In some cases, the tensioning drum is coupled to the tensioning gear such that the tensioning drum moves axially when the tensioning gear rotates along the ramp to the base frame of the surgical instrument. In some cases, the dynamic preload tensioner includes a spring engaged with the tensioning drum such that a static preload is applied to the flexible tensioning element. In some cases, the tensioning drum is movable to compress the spring such that the coils of the spring contact each other when the path changes.

[0018] In some embodiments, methods and / or operations include applying a static preload to the flexible tensioning element prior to moving the dynamic preload tensioner.

[0019] In some embodiments, moving the dynamic preload tensioner includes compressing a spring such that coils of the spring contact each other when the tension in the flexible tensioning element reaches a predefined tension.

[0020] In some embodiments, moving the dynamic preload tensioner includes rotating a lead screw of the surgical instrument to increase tension in the flexible tensioning element. In some embodiments, the dynamic preload tensioner includes a lead screw and an arm coupled to the lead screw. In some cases, rotating the lead screw includes longitudinally moving the arm of the surgical instrument to increase tension in the flexible tensioning element. In some cases, the arm is movable longitudinally along the lead screw to change its path as the lead screw rotates.

[0021] In some embodiments, moving the dynamic preload tensioner includes moving an elongated body of the surgical instrument relative to a chassis of the surgical instrument to increase tension in a flexible tensioning element. In some embodiments, the surgical instrument includes an elongated body extending distally from the chassis. The distal end of the elongated body is coupled to, for example, a distal member. The elongated body encompasses, for example, at least a portion of a path of the flexible tensioning element. The dynamic preload tensioner is configured to move the elongated body relative to the chassis to change the path as the dynamic preload tensioner moves relative to the chassis.

[0022] In some embodiments, moving the dynamic preload tensioner includes rotating a cam to engage the flexible tensioning element to increase tension in the flexible tensioning element. In some embodiments, the dynamic preload tensioner includes a cam rotatable relative to the chassis. A surface of the cam is, for example, configured to engage the flexible tensioning element to change path when the cam rotates.

[0023] In some embodiments, moving the dynamic preload tensioner includes moving the dynamic preload tensioner to one of a plurality of discrete positions to apply one of a plurality of discrete preloads to the flexible tensioning element. Maintaining the position of the dynamic preload tensioner includes, for example, locking the dynamic preload tensioner to one of the plurality of discrete positions. In some embodiments, the dynamic preload tensioner is lockable to one of the plurality of discrete positions to apply one of the plurality of discrete preloads to the flexible tensioning element.

[0024] In some embodiments, moving the dynamic preload tensioner includes operating a drive output of a surgical instrument to which the surgical instrument is mounted. In some embodiments, the system further includes an instrument drive unit to releasably support the surgical instrument. The instrument drive unit includes, for example, a drive output operably connected to the dynamic preload tensioner such that the dynamic preload tensioner moves relative to the chassis when the drive output is activated. In some cases, operating the drive output includes twisting the flexible tensioning element. In some cases, the method and / or operation further includes receiving information indicating that the surgical instrument is mounted to the surgical manipulator. In some cases, the drive output is operable to engage the dynamic preload tensioner such that the flexible tensioning element is twisted to change the path of the flexible tensioning element.

[0025] In some embodiments, moving the dynamic preload tensioner includes moving a pin mounted to a chassis of the surgical instrument. In some embodiments, the dynamic preload tensioner includes a pin movably mounted to the chassis and engageable with the flexible tensioning element to change a path of the flexible tensioning element when the pin is moved relative to the chassis.

[0026] In some embodiments, moving the dynamic preload tensioner includes pivotally mounting a plate to a chassis of the surgical instrument. In some embodiments, the dynamic preload tensioner includes a tensioning plate pivotally mounted to the chassis to change path when the tensioning plate rotates relative to the chassis.

[0027] In some embodiments, the system further includes a manually operable tensioning tool.

[0028] The foregoing advantages may include, but are not limited to, those advantages described below and elsewhere herein. A flexible tensioning element, enabling the transfer of a load from a first end to a second end, may require an initial load, which causes the flexible tensioning element to be tensioned. When the flexible tensioning element is tensioned, it is able to transfer additional load from its first end to its second end. The path of the flexible tensioning element can be adjusted to apply a preload to the flexible tensioning element. A flexible tensioning element having a preload can transfer a greater proportion of the input load toward its distal end to drive a distal component to which the flexible tensioning element is physically coupled. In this regard, the input load is not used to pull the flexible tensioning element, but rather to steer the distal component to which the flexible tensioning element is coupled.

[0029] The adjustable path of the flexible tensioning element can further improve the adaptability of the surgical instrument as the conditions of the surgical instrument change. In some cases, during the manufacture of the surgical instrument, the flexible tensioning element is provided with an initial preload to inhibit relative movement of the surgical instrument's components prior to use during a surgical procedure. As time passes between the completion of the surgical instrument's manufacture and its operation during a surgical procedure, the initial preload can decrease over time, for example due to instrument aging, creep, stress relaxation, relative movement between instrument components, and other mechanisms that can reduce the initial preload. The path of the flexible tensioning element can be adjusted so that the preload in the flexible tensioning element can be precisely controlled, for example, to maintain the preload within a desired range, to maintain the preload above a predefined threshold, etc. The preload can be adjusted to inhibit excessive friction between the flexible tensioning element and the surface subjected to the flexible tensioning, while also reducing the likelihood that the flexible tensioning element will become unstuck during operation of the surgical instrument.

[0030] Additionally, because the preload can be adjusted after the surgical instrument is manufactured, the initial preload set during manufacturing can be smaller, as the preload can be further adjusted (e.g., increased) after manufacturing is complete. When the initial preload is smaller, the likelihood of material changes in the flexible tensioning element (e.g., due to creep or stress relaxation) can be lower.

[0031] The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other potential features, aspects, and advantages will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic side view of a surgical instrument including a dynamic tensioner.

[0033] Figure 2 is a side view of a surgical instrument mounted to a manipulator.

[0034] Figure 3A It is a side view of a surgical instrument.

[0035] Figure 3B yes Figure 3A A perspective view of a transmission unit for a surgical instrument.

[0036] Figure 4 It is the process of operating the dynamic tensioner.

[0037] Figure 5A is a top perspective view of the dynamic tensioner.

[0038] Figure 5B yes Figure 5A Top view of a dynamic tensioner.

[0039] Figure 5C yes Figure 5A Top perspective view of the tensioning drum of a dynamic tensioner.

[0040] Figure 5D yes Figure 5C Top perspective exploded view of the tensioning drum of a dynamic tensioner.

[0041] Figure 5E yes Figure 5A Schematic side view of a dynamic tensioner including the spring in the deployed position.

[0042] Figure 5F yes Figure 5E Schematic side view of a dynamic tensioner with the spring in a compressed position.

[0043] Figure 6 is a top perspective view of an example of a dynamic tensioner.

[0044] Figure 7A is a side sectional view of a dynamic tensioner.

[0045] Figure 7B yes Figure 7A Schematic side view of a rotatable member of a dynamic tensioner in a first position and in a second position.

[0046] Figure 7C yes Figure 7A An example of a rotatable member of a dynamic tensioner.

[0047] Figure 8 is a top view of an example of a dynamic tensioner.

[0048] Figure 9A and Figure 9B are left and right perspective side views, respectively, of an example of a dynamic tensioner.

[0049] Figure 10 is a schematic side view of an example of a dynamic tensioner.

[0050] Figure 11A is a top view of a dynamic tensioner in a first position.

[0051] Figure 11B is Figure 11A a top view of a dynamic tensioner in a second position.

[0052] Figures 12A-12E is a diagram of a drive component coupled to a flexible tensioning element.

[0053] Figure 13A and Figure 13B is a diagram of a dynamic tensioner and a flexible tensioning element.

[0054] The same reference numbers and designations in the various drawings represent the same elements. DETAILED DESCRIPTION

[0055] Flexible tensioning elements (e.g., cables, cable-hypotube combinations, etc.) of surgical instruments include a preload tension that enables an input tension load to be transmitted through the flexible tensioning element from a first end to a second end. The preload tension can also inhibit the flexible tensioning element from becoming slack when another flexible tensioning element is loaded such that the flexible tensioning element is slack. The preload tension corresponds to, for example, a tension present in the flexible tensioning element in the absence of an input tension load to drive a distal component coupled to the flexible tensioning element, a tension present in the flexible tensioning element prior to an input tension load being applied to drive the distal component, a tension present in the flexible tensioning element to reduce slack of the flexible tensioning element, etc. As described herein, the preload tension can be adjusted, for example, after manufacturing of the surgical instrument is complete, to improve operability and adaptability of the surgical instrument.

[0056] As described herein, an instrument tensioning element initially experiences a first preload tension, which may be zero or another value sufficient to maintain the mechanical integrity of the instrument during transport, storage, etc. Prior to or during instrument operation, a controller increases the first preload tension of the instrument tensioning element to a second preload tension that is greater than the first preload tension. During operation, the tensioning element experiences two types of tension—the second preload tension and an actuation tension load used to drive the distal component of the instrument to which the tensioning element is coupled. Following operation, the second preload tension of the instrument tensioning element is optionally reduced to a value less than the second preload tension, such as the first preload tension. This reduction in preload tension can be controlled by the controller or manually or mechanically when the instrument is removed from its instrument carrier after operation. This cycle of dynamically increasing and decreasing the preload tension of the instrument tensioning element can optionally be repeated during one or more subsequent instrument operations or uses. Thus, in addition to applying changes in the actuation tension load used to move or permit movement of the distal component, the instrument tensioning element experiences dynamic changes in preload tension that are at least partially controlled by the controller.

[0057] Figure 1 An example of a surgical system 100 is depicted, including a surgical instrument 101, which includes a chassis 102, drive components 104a, 104b, a flexible tensioning element 106, and a distal component 108. Drive component 104b is, for example, a dynamic preload tensioner drive component that is driven to operate a dynamic preload tensioner 116. Drive component 104a is, for example, a flexible tensioning element drive component that is driven to drive flexible tensioning element 106. Chassis 102 is located at a proximal end portion 110 of surgical instrument 101, and distal component 108 is located at a distal end portion 111 of surgical instrument 101. Drive components 104a, 104b are mounted in chassis 102, i.e., near or at proximal end portion 110 of surgical instrument 101. The drive components 104a, 104b include, for example, mechanical components that bear mechanical loads from the drive system 112. The drive components 104a, 104b are, for example, driven components that move when driven by the drive system 112. The flexible tensioning element 106 is coupled between the drive component 104a and the distal component 108. The flexible tensioning element 106 extends along a path, for example, between the drive component 104a and the distal component 108. The drive component 104a transfers an actuation load applied to the drive component 104a to the flexible tensioning element 106.

[0058] The surgical instrument 101 also includes a dynamic preload tensioner 116. In some cases, the dynamic preload tensioner 116 is mounted in the chassis 102. In some embodiments, the dynamic preload tensioner 116 is at least partially mounted in the chassis 102 and / or completely contained within the chassis 102. The dynamic preload tensioner 116 is coupled to the drive component 104b. In some cases, the drive component 104a is coupled to a drive mechanism to transfer a load applied to the drive component 104b to the flexible tensioning element 106. The dynamic preload tensioner 116 is configured to be driven by the drive component 104b to move relative to the chassis 102. In this regard, the dynamic preload tensioner 116 can be controllably positioned to change the path of the flexible tensioning element 106 when the dynamic preload tensioner 116 moves relative to the chassis 102.

[0059] In some embodiments, when drive component 104a is driven, drive component 104a applies an axial (e.g., lengthwise) actuation load to flexible tensioning element 106. The axis of the axial load is, for example, parallel to the axis of tension in flexible tensioning element 106. When drive component 104b is driven, drive component 104b operates dynamic preload tensioner 116 to apply a transverse (e.g., crosswise) load to flexible tensioning element 106. For example, the transverse load bends flexible tensioning element 106 in a manner that induces tension in flexible tensioning element 106. In this regard, when drive component 104b is not driven to operate dynamic preload tensioner 116, a first tension exists in flexible tensioning element 106. When driven, drive component 104b induces a second tension to exist in the flexible tensioning element. The first tension corresponds to the preload tension in flexible tensioning element 106 absent operation of dynamic preload tensioner 116, and the second tension corresponds to the preload tension in flexible tensioning element 106 after drive component 104b is operated. Due to the operation of the dynamic preload tensioner 116 , the second tension is greater than the first tension.

[0060] Despite Figure 1 Although a single flexible tensioning element 106 is described and illustrated in the drawings, the examples described herein are applicable to surgical instruments having a dynamically preloaded tensioner that simultaneously changes the path of one flexible tensioning element and the path of another flexible tensioning element. The two flexible tensioning elements may be coupled to the same drive component, such as drive component 104a, or the flexible tensioning elements may be coupled to independently operable drive components.

[0061] Figures 12A to 12EVarious examples of configurations of actuating components for driving flexible tensioning elements 1202a and 1202b are depicted. When flexible tensioning element 1202a is actuated, the distal component to which flexible tensioning element 1202a is connected moves in a first direction of freedom. When flexible tensioning element 1202b is actuated, the distal component to which flexible tensioning element 1202b is also connected moves in a second direction of freedom. In this regard, flexible tensioning elements 1202a and 1202b are actuated in a manner that precisely controls, for example, bidirectional movement of the distal component in the aforementioned degrees of freedom.

[0062] Figures 12A to 12C Depicted is a mechanism in which the flexible tensioning elements 1202a, 1202b are driven by separate drive components. In some embodiments, as Figure 12A As shown, drive system 112 applies forces to drive components 1204a, 1204b. The first and second drive components are configured to translate when a force is applied thereto, for example, to apply tension to flexible tensioning elements 1202a, 1202b. For example, drive system 112 translates a first drive input to apply force 1206a to flexible tensioning element 1202a and translates a second drive input to apply force 1206b to flexible tensioning element 1202b. By applying force 1206a, drive system 112 drives drive component 1204a proximally to apply tension to flexible tensioning element 1202a. By applying force 1206b, drive system 112 drives drive component 1204b proximally to apply tension to flexible tensioning element 1202b. The drive system 112 applies forces 1206a, 1206b in a manner to control the movement of the distal member, such as applying force 1206a to move the distal member in a first degree of freedom and applying force 1206b to move the distal member in a second degree of freedom.

[0063] In some cases, such as Figure 12B As shown, the drive components 1208a, 1208b do not translate due to the force applied by the drive system 112, but rather rotate about rotation centers 1210a, 1210b, respectively, in response to the force applied by the drive system 112. The drive components 1208a, 1208b are, for example, rods that are rotatable about rotation centers 1210a, 1210b, respectively. Flexible tensioning elements 1202a, 1202b are attached to the drive components 1208a, 1208b, respectively, such that a distally directed force 1211a, 1211b applied to the rods causes a proximally directed force (e.g., tension) to be applied to the flexible tensioning elements 1202a, 1202b, respectively. When the drive component 1208a rotates, for example, as Figure 12BAs shown, when rotating counterclockwise about the center of rotation 1210a, the drive component 1208a applies tension 1212a to the flexible tensioning element 1202a. The drive component 1208a rotates in response to the force 1211a applied by the drive system 112 and thus applies tension 1212a. When the drive component 1208b rotates, for example, Figure 12B As shown, drive member 1208b applies tension 1212b to flexible tensioning element 1202b when rotated clockwise about center of rotation 1210b. Drive member 1208b rotates in response to force 1211b applied by drive system 112 and thereby applies tension 1212b.

[0064] In some cases, such as Figure 12C As shown, rather than applying a force to rotate the drive components, drive system 112 applies torques 1216a, 1216b to rotate drive components 1218a, 1218b, respectively. Drive components 1218a, 1218b are, for example, rotatable capstans to which flexible tensioning elements 1202a, 1202b are attached. When rotated by torques 1216a, 1216b, the capstans apply tension 1219a, 1219b to flexible tensioning elements 1202a, 1202b, respectively. Drive component 1218a rotates in response to drive system 112 applying torque 1216a, and drive component 1218b rotates in response to drive system 112 applying torque 1216b. As the drive members 1218a, 1218b rotate, the flexible tensioning elements 1202a, 1202b are wrapped around the drive members 1218a, 1218b such that tensioning forces 1219a, 1219b are applied to the flexible tensioning elements 1202a, 1202b.

[0065] In some cases, the flexible tensioning elements 1202a, 1202b are attached to separate drive components, e.g., as described with respect to Figures 12A-12C As described, to move the distal component in a first direction, one of the drive components is driven to apply tension to one of the flexible tensioning elements, while the other drive component is operated to maintain minimum tension in the other flexible tensioning element. Minimum tension is applied to the other flexible tensioning element to prevent slack. Tension is applied to the flexible tensioning element to move the distal component in the first direction. Furthermore, slack is applied to the other flexible tensioning element to prevent obstruction of movement of the distal component in the first direction. On the other hand, to move the distal component in a second direction, the other flexible tensioning element is driven. Slack is applied to the flexible tensioning element to prevent obstruction of movement of the distal component in the second direction.

[0066] In some embodiments, the flexible tensioning element is not attached to a separate drive component, but is attached to the same drive component. These examples areFigure 12D and Figure 12E In some cases, such as Figure 12D As shown, drive system 112 applies forces 1220a, 1220b to a single drive member 1222 to apply tension to flexible tensioning elements 1202a, 1202b attached to drive member 1222. When drive member 1222 is driven by forces 1220a, 1220b, thereby rotating in a first direction in response to force 1220a and in a second direction in response to force 1220b, drive member 1222 rotates about a rotation center 1223. Force 1220a drives flexible tensioning element 1202b and relaxes flexible tensioning element 1202a, and force 1220b drives flexible tensioning element 1202a and relaxes flexible tensioning element 1202a. The drive member is, for example, a rod to which the flexible tensioning elements 1202a, 1202b are attached, and the flexible tensioning elements 1202a, 1202b are attached to opposite lever arms of the rod, for example lever arms extending in opposite directions away from the rotation center 1223.

[0067] In some cases, such as Figure 12E As shown, instead of applying force to move the drive component, drive system 112 applies torque 1224 to a single drive component 1226 to drive flexible tensioning element 1202b. Torque 1224 causes flexible tensioning element 1202a to relax. Drive system 112 applies torque to drive component 1226 in the opposite direction of torque 1224 to drive flexible tensioning element 1202a. This torque causes flexible tensioning element 1202b to relax. For example, single drive component 1226 is a rotatable capstan.

[0068] Return to reference Figure 1 If the drive component 104a is coupled to a plurality of flexible tensioning elements, when the drive component 104a is driven in a first direction, the drive component 104a applies an actuation tension load to one of the flexible tensioning elements to move the distal end effector in the first direction. In some cases, the other of the flexible tensioning elements is relaxed. When the drive component 104a is driven in a second direction, the drive component 104a applies an actuation tension load to another of the flexible tensioning elements to move the distal end effector in the second direction. The two flexible tensioning elements are, for example, wound around the drive component 104a in opposite directions. In some embodiments, the flexible tensioning elements, when driven, apply a load to move the distal end component at the joint, thereby causing the distal end component to move in a clamping motion, a pitch motion, a yaw motion, a roll motion, etc.

[0069] To prevent the relaxed flexible tensioning element from experiencing unacceptably low tension or slack when one of the flexible tensioning elements is actuated while the other is relaxed, the flexible tensioning element can be preloaded with tension such that an acceptable minimum tension always exists on the tensioning element during instrument operation. For example, the acceptable minimum tension can be equal to or greater than the minimum tension used in the flexible tensioning element during steering of the distal component. As a result, when actuation tension is applied in one flexible tensioning element, the other flexible tensioning element relaxes but does not slack due to the actuation tension applied to the opposing tensioning element.

[0070] In some examples, surgical system 100 includes controller 117. Controller 117 is configured to execute instructions stored on memory 119 to perform operations, for example, to control drive system 112. Controller 117 operates dynamic preload tensioner 116, causing it to move, for example, relative to chassis 102, to adjust the path of flexible tensioning element 106. This path adjustment, i.e., an increase in path length, adjusts the tension in flexible tensioning element 106. In some cases, controller 117 operates an actuator of drive system 112 to move dynamic preload tensioner 116. Drive system 112 applies a load to drive component 104b, which in turn applies a load to dynamic preload tensioner 116. Under the load applied by drive component 104b, dynamic preload tensioner 116 moves relative to chassis 102.

[0071] The flexible tensioning element 106 is, for example, a cable, a cable and hypotube combination, a thread, a filament, a bundle of filaments, a braided filament, a thread, a rope, a twisted filament, or other element in which tension can exist. In some cases, the flexible tensioning element 106 is susceptible to creep, stress relaxation, or other changes in the material properties of the flexible tensioning element 106. The flexible tensioning element 106 is formed, for example, from a metal or a polymer. When the flexible tensioning element 106 is formed from a polymer, for example, the flexible tensioning element 106 is polyethylene, a liquid crystal polymer, a polyester, or the like.

[0072] In some embodiments, distal component 108 is located at a distal portion of a tubular member 115 attached to base 102. Tubular member 115, for example, is a shaft of a minimally invasive surgical instrument. Tubular member 115, for example, is an elongated body through which flexible tensioning element 106 extends. Tubular member 115 extends distally from base 102. The distal end of tubular member 115 is coupled to distal component 108. Tubular member 115 encompasses at least a portion of the path of flexible tensioning element 106. For example, tubular member 115 encompasses flexible tensioning element 106 as it extends from base 102 to distal component 108. In some instances, when a load is applied to flexible tensioning element 106 to cause distal component 108 to deflect, tubular member 115 supports distal component 108 to secure its position relative to base 102.

[0073] In some embodiments, the dynamic preload tensioner 116 may be in a first position 118 (at Figure 1 ) and a second position 120 (shown in solid lines in FIG. Figure 1 The dynamic preload tensioner 116 can be moved between a first position 118 and a second position 120, for example. In some cases, the first position 118 corresponds to an initial position of the dynamic preload tensioner 116, e.g., the position of the dynamic preload tensioner 116 after manufacturing of the surgical instrument 101 is complete, or when the dynamic preload tensioner 116 is not in operation. In the first position 118 of the dynamic preload tensioner 116, a first preload tension exists in the flexible tensioning element 106. In the second position 120 of the dynamic preload tensioner 116, a second preload tension exists in the flexible tensioning element 106. The second preload tension is greater than the first preload tension. In some cases, the first tension is zero. In some cases, the first tension corresponds to an initial preload tension set during manufacturing of the surgical instrument 101. For example, the first tension is a portion of the preload tension that exists in the flexible tensioning element 106 after the dynamic preload tensioner 116 is operated to induce the second tension.

[0074] In some embodiments, dynamic preload tensioner 116 is positioned to apply an adjustable preload tension to flexible tensioning element 106 as dynamic preload tensioner 116 moves to adjust the path of flexible tensioning element 106. If an initial preload tension exists in flexible tensioning element 106, the adjustable preload tension applied to flexible tensioning element 106 results in a total preload tension in flexible tensioning element 106 that corresponds to, for example, the sum of the adjustable preload tension and the initial preload tension portion in flexible tensioning element 106.

[0075] ReferenceFigure 2 In some embodiments, the surgical instrument 101 is mounted to a manipulator 200. The manipulator 200 is, for example, a remotely controllable manipulator that can be operated by a surgeon at a location remote from the manipulator 200. For example, the surgeon operates a control input on a console that communicates with the manipulator 200, and the console generates a control signal for a drive system of the manipulator 200 to control the movement of a joint (e.g., joint 202) of the manipulator 200. For example, the control signal selectively activates an actuator of the drive system of the manipulator 200. Such surgical system structures are known and can be found in, for example, a device commercialized by Intuitive Surgical, Inc. of Sunnyvale, California. Surgical systems and are seen in various patents, such as U.S. Patent Nos. US 6,246,200 Bl (filed August 3, 1999), US 6,331,181 Bl (filed October 15, 1999) and US 6,788,018 Bl (filed December 20, 2001), all of which are incorporated herein by reference.

[0076] Manipulator 200 includes, for example, an instrument holder 204 to which surgical instrument 101 may be mounted. Instrument holder 204 may, for example, releasably support surgical instrument 101. Instrument holder 204 includes one or more actuators that are part of a drive system for manipulator 200. For example, instrument holder 204 is a mechanical interface that connects the drive system of manipulator 200 to a driven component of the surgical instrument. In some cases, when surgical instrument 101 is mounted to instrument holder 204, the drive system of manipulator 200 engages with drive components 104a, 104b of surgical instrument 101 such that activation of the drive system drives drive components 104a, 104b. For example, the drive system of manipulator 200 may include multiple independently controllable drive outputs that are connected to drive components 104a, 104b of surgical instrument 101. In some examples, when surgical instrument 101 is mounted to instrument holder 204 , one drive output is positioned to drive drive component 104 a and another of the drive outputs is positioned to drive drive component 104 b .

[0077] In some examples, the drive system of manipulator 200 corresponds to Figure 1 As a result, the drive system of the manipulator 200 can operate in conjunction with the drive components 104a, 104b to apply a load to the flexible tensioning element 106 and / or cause movement of the dynamic preload tensioner 116. For example, a drive output of the drive system of the manipulator 200 can be operatively connected to the dynamic preload tensioner 116 such that the dynamic preload tensioner 116 moves relative to the chassis 102 when the drive output is activated.

[0078] Figure 3A Another example of a surgical instrument 300 that can be mounted to manipulator 200 is depicted. Surgical instrument 300 includes a driven interface assembly 302, e.g., a mechanical interface that mechanically couples a drive component 304 of surgical instrument 300 with a drive system of manipulator 200. Drive component 304 of surgical instrument 300 includes, for example, a driven disk of surgical instrument 300 that can be rotated by the drive system of manipulator 200.

[0079] Surgical instrument 300 also includes a transmission unit 306, a tubular member 308 (e.g., an instrument shaft), a joint 310, and a distal end member 312. Transmission unit 306 transmits the load applied by the drive system of manipulator 200 to move distal end member 312. Distal end member 312 is, for example, an end effector operated during a surgical procedure. Joint 310 is, for example, a wrist joint that is movable to control the orientation of distal end member 312.

[0080] In some embodiments, the surgical instrument 300 includes a flexible tensioning element coupled to a drive component 304 mounted in a chassis 313 of the surgical instrument 300. Figure 1 As described with reference to the flexible tensioning elements 106 , each flexible tensioning element extends along a path between the drive member and the distal member. In some cases, multiple flexible tensioning elements extend from a single drive member to the distal member 312 to control the movement of the distal member 312 along the degrees of freedom.

[0081] The surgical instrument 300 includes one or more dynamic tensioners. In some embodiments, the surgical instrument includes a single dynamic tensioner. One of the drive components 304 is coupled to the dynamic tensioner, and another of the drive components is coupled to a flexible tensioning element, such as a proximal end of the flexible tensioning element. In embodiments where the surgical instrument includes multiple flexible tensioning elements, the single dynamic tensioner can be moved relative to the chassis 313 to change the path of one, some, or all of the flexible tensioning elements.

[0082] In other embodiments, the surgical instrument includes multiple dynamic tensioners. In these embodiments, the surgical instrument includes a dynamic tensioner for each flexible tensioning element of surgical instrument 300, for example. Alternatively or additionally, the surgical instrument includes a dynamic tensioner associated with each drive component. Each dynamic tensioner adjusts the path of its associated flexible tensioning element when its associated drive component is driven. For example, one separate dynamic tensioner is positioned to controllably change the tension in a first flexible tensioning element, and a second separate dynamic tensioner is positioned to controllably change the tension in a second flexible tensioning element.

[0083] like Figure 13A As shown, in some embodiments, a first dynamic tensioner 1302a is positioned to engage a flexible tensioning element 1304a, and a second dynamic tensioner 1302b is positioned to engage a flexible tensioning element 1304b. The flexible tensioning elements 1304a, 1304b are driven to move the distal portion 1307 along a single degree of freedom, e.g., along a first degree of freedom if the flexible tensioning element 1304a is driven, and along a second degree of freedom if the flexible tensioning element 1304b is driven. For example, the first dynamic tensioner 1302a and the second dynamic tensioner 1302b are independently driven, e.g., operated by different drive components 1306a, 1306b, and driven by different actuators of the drive system 112. In this regard, the preload tension applied to the first flexible tensioning element 1304a can be set in a manner independent of the preload tension applied to the second flexible tensioning element 1304b. Conversely, in a configuration such as Figure 13B In some embodiments shown, a single dynamic tensioner 1308 is positioned to engage both flexible tensioning elements 1304a, 1304b. The dynamic tensioner 1308 is operated by a single drive component (not shown) and is driven by a single actuator of the drive system 112. In this regard, the drive system 112 operates the single dynamic tensioner 1308 to apply a preload tension to the flexible tensioning elements 1304a, 1304b.

[0084] The transmission unit 306 includes mechanical components, such as gears, rods, universal joints, cables, etc., to transfer loads from the drive component 304 of the surgical instrument 300 to the distal component 312. The mechanical components of the transmission unit 306, for example, form a mechanism in the proximal portion of the surgical instrument 300 that mechanically couples the flexible tensioning element of the surgical instrument 300 with the drive component 304 of the driven interface assembly 302.

[0085] In some embodiments, a mechanical component aligns the proximal end of the flexible tensioning element with one of the drive components (e.g., Figure 1 Alternatively or additionally, the mechanical component is mechanically coupled to a portion of the flexible tensioning element between the distal end and the proximal end of the flexible tensioning element and one of the drive components, for example, Figure 1 In this case, the drive component, when driven, moves the dynamic tensioner to adjust the path of the flexible tensioning element (eg, by applying a lateral load on the flexible tensioning element).

[0086] If the drive component 304 includes a driven capstan, rotation of the driven capstan exerts a tension load on the flexible tension member, e.g., pulling the flexible tension member. The flexible tension member then exerts a load on a mechanical linkage in the distal component 312 to move the distal component 312, e.g., to reposition or reorient the linkage of the distal component 312.

[0087] In some cases, the tubular member 308 is rigid. In some implementations, the tubular member 308 is bendable relative to the transmission unit 306. The tubular member 308 may, for example, be elastically bendable such that the tubular member 308 returns to its original shape upon removal of the force that caused the tubular member 308 to bend. In other cases, however, the tubular member is flexible but does not return to its initial shape after being bent until the controller generates a command to the manipulator to cause the tubular member to return to the initial shape.

[0088] Figure 4 A flowchart depicting a process 400, e.g., performed by the controller 117 to operate a dynamic tensioner, is shown. The process 400 is performed, for example, by the controller 117 in conjunction with the surgical system 100 described with reference to Figure 1 The process 400 is performed, for example, by the controller 117 in conjunction with the surgical system 100 described with reference to

[0089] At operation 402, the controller 117 moves a dynamic tensioner (e.g., the dynamic preload tensioner 116) of a surgical instrument (e.g., the surgical instrument 101) to increase tension in a flexible tension member (e.g., the flexible tension member 106) of the surgical instrument.

[0090] At operation 404, the controller 117 drives the flexible tension member to move a distal component, e.g., the distal component 108, while maintaining the position of the dynamic tensioner.

[0091] In some implementations, prior to moving the dynamic tensioner to increase tension, the controller 117 receives information indicating that the surgical instrument has been installed. For example, the information indicates that the surgical instrument has been installed onto a manipulator. In some examples, the controller 117 moves the dynamic tensioner when the controller 117 receives the information indicating that the surgical instrument has been installed. In some implementations, the controller 117 receives information indicating a predefined tension, e.g., a target value for the tension in the flexible tension member. In some cases, the controller 117 determines when the tension in the flexible tension member has reached the predefined tension. The controller 117 maintains the position of the dynamic tensioner in response to determining that the tension in the flexible tension member has reached the predefined tension.

[0092] In some embodiments, the controller 117 moves the dynamic tensioner of the surgical instrument by commanding the drive system 112 to drive a corresponding drive component (e.g., drive component 104b) to move the dynamic tensioner from a first position to a second position. In response to determining that the tension in the flexible tensioning element 106 has reached a predefined tension, the controller 117 maintains the position of the dynamic preload tensioner 116 such that the tension in the flexible tensioning element 106 remains at or above the predefined tension. If the controller 117 drives the drive component to move the dynamic tensioner, the controller 117 drives the drive component until the controller 117 receives information indicating that the predefined tension has been reached.

[0093] Alternatively or additionally, controller 117 moves the dynamic tensioner of the surgical instrument while simultaneously monitoring the tension in the flexible tensioning element. For example, controller 117 determines the tension in flexible tensioning element 106 by monitoring the tension in flexible tensioning element 106 during movement of dynamic preload tensioner 116. In some embodiments, to monitor the tension in the flexible tensioning element, controller 117 receives information indicating the tension in the flexible tensioning element. This information is received, for example, from a sensor configured to measure the tension in the flexible tensioning element. The sensor is, for example, a torque sensor associated with an actuator that drives a drive component to drive the dynamic tensioner. The torque sensor generates a signal indicating the torque applied by the actuator, and in some cases, controller 117 determines the tension in the flexible tensioning element based on the torque. In some cases, the sensor is a torque sensor associated with an actuator that drives a drive component to drive the flexible tensioning element. In one example, when controller 117 drives a first drive component to move the dynamic tensioner, thereby increasing the tension in the flexible tensioning element, controller 117 determines when the torque is measured by a torque sensor associated with a second drive component configured to drive the flexible tensioning element. After determining that the torque measured by the torque sensor indicates that the tension in the flexible tensioning element has reached a predefined tension, the controller maintains the position of the first drive component. Various other sensors (such as various types of strain or torque sensors mounted on corresponding drive components or other components in a drive train associated with the flexible tensioning element) can be used to sense the tension in the flexible tensioning element.

[0094] In some embodiments, the controller 117 drives the flexible tensioning element by driving a drive member (e.g., drive member 104a). In this regard, in some cases, the controller 117 drives one drive member to move the dynamic tensioner and drives a second drive member to drive the flexible tensioning element to move the distal member.

[0095] Figures 5A-11BVarious examples of dynamic tensioners are described that, when operated, change the path of a flexible tensioning element of a surgical instrument. In each of these examples and other examples described herein, the path of the flexible tensioning element is changed by operating the dynamic tensioner via a controller. In some cases, the dynamic tensioner applies a transverse load to the flexible tensioning element, which adjusts the path of the flexible tensioning element. In some cases, the dynamic tensioner causes an axial load to be applied to the flexible tensioning element to adjust the path of the flexible tensioning element. This axial load is independent of the axial load applied to the flexible tensioning element to steer the distal component. The change in the path of the flexible tensioning element causes the flexible tensioning element to experience a tension force, such as a preload tension. The dynamic tensioner is operable to generate an adjustable preload tension on the flexible tensioning element, allowing the preload tension to be applied or released. When the adjustable preload tension reaches a desired level, the preload tension can be locked to maintain the adjustable dynamic preload tension at the desired level while simultaneously actuating the flexible tensioning element to steer the distal component. This tension locking can be accomplished by holding the dynamic preload tensioner in place after the desired preload tension value is established in the tensioning element, or by actively sensing the tension in the tensioning element and continuing to dynamically adjust the dynamic tensioner to maintain the desired preload tension.

[0096] As about Figure 1 As described in the examples of the present invention, the path of the flexible tensioning element is altered to apply preload tension to the flexible tensioning element. In some embodiments, the path is extended by longitudinally extending a portion of the path. In some embodiments, the path is extended by adjusting the angle between a first portion of the path and a second portion of the path. In some embodiments, the path is extended by adding a bend in the path (e.g., by bending the flexible tensioning element).

[0097] Figure 5A and Figure 5B An example of a dynamic tensioner 500 for a surgical instrument is depicted, comprising a tensioning drum 502 positioned to engage a flexible tensioning element 504a. The tensioning drum 502 is axially movable so that it engages the flexible tensioning element 504a and changes the path of the flexible tensioning element 504a. In some examples, the tensioning drum 502 is axially movable relative to a chassis of the surgical instrument. The tensioning drum 502 is, for example, a cylindrical member movable along its central axis and positioned to engage the flexible tensioning element 504a as it moves along the central axis.

[0098] In some embodiments, to change the path of the flexible tensioning element 504a, the tensioning drum 502 redirects the path of the flexible tensioning element 504a when the tensioning drum 502 moves to engage the flexible tensioning element 504a. The flexible tensioning element 504a extends along a first portion of its path from the drive member 506 to the tensioning drum 502. The flexible tensioning element 504a then abuts the tensioning drum 502, such as the top surface 508 of the tensioning drum 502, causing the path of the flexible tensioning element 504a to be redirected. Specifically, the path is redirected toward the distal end of the surgical instrument. In some cases, the tensioning drum 502 includes an aperture 510 through which the flexible tensioning element 504a passes. The path of the flexible tensioning element 504a extends from the drive member 506 toward the aperture 510, and then through the aperture 510 while the flexible tensioning element 504a abuts the top surface 508 of the tensioning drum 502. The path of the flexible tensioning element 504a then extends toward the joint of the distal component.

[0099] As the tensioning drum 502 moves axially, the tensioning drum 502 (e.g., the top surface 508 of the tensioning drum 502) engages the flexible tensioning element 504a and causes the flexible tensioning element 504a to move with the tensioning drum 502. Because the flexible tensioning element 504a abuts the tensioning drum 502, the movement of the tensioning drum 502 causes the path of the flexible tensioning element 504a to change. In some embodiments, the movement of the tensioning drum 502 causes the path change by relocating a bend point in the path (e.g., the point at which the path of the flexible tensioning element 504a is redirected).

[0100] In some embodiments, to move the tensioning drum 502, the dynamic tensioner 500 includes a drive mechanism 512 that, when driven, causes axial movement of the tensioning drum 502. The drive mechanism 512 includes a drive component 506 that is driven by, for example, a drive system of the manipulator 200. The drive component 506 transmits a load through a gear system. In some examples, when the drive component 506 is driven to rotate, a gear 516 coupled to the drive component 506 is driven to rotate a gear 518, which in turn rotates a tensioning gear 520. The tensioning gear 520, when rotated, drives the tensioning drum 502 to move axially relative to the tensioning gear 520. Gears 516, 518, and the tensioning gear 520 are all rotatably mounted to the chassis of the surgical instrument.

[0101] Reference Figure 5C and Figure 5D For example, the tensioning gear 520 abuts against a ramp 522 defined by the chassis of the surgical instrument, for example, a ramp formed on a surface 524 of the chassis of the surgical instrument. The ramp 522 increases in height relative to the surface 524 in a clockwise direction, as shown in FIG. Figure 5DAs shown in FIG. 1 , the top surface of ramp 522 follows a helical path that extends away from a surface 524 of the chassis. As tensioning gear 520 rotates along ramp 522, tensioning gear 520 follows this helical path. Tensioning drum 502 is coupled to tensioning gear 520 so that tensioning drum 502 moves axially as tensioning gear 520 rotates along ramp 522 of the chassis of the surgical instrument.

[0102] In some embodiments, the tensioning drum 502 is keyed to the chassis so that the tensioning drum 502 does not rotate when the tensioning gear 520 rotates. Figure 5D The tension drum 502 is secured to the chassis by a locking element 525 that engages a corresponding locking element on the bottom surface of the tension drum 502. The locking element 525 is, for example, a protrusion that extends through the tensioning gear 520 and engages with a corresponding bore on the bottom surface of the tension drum 502. Alternatively, the locking element 525 is a bore that engages with a corresponding protrusion on the bottom surface of the tension drum 502. The engagement between the locking element 525 and the corresponding locking element on the tension drum 502 inhibits relative rotation of the chassis and the tension drum 502, such that when the tensioning gear 520 rotates, the tension drum 502 does not rotate. Conversely, when the tensioning gear 520 rotates, both the tensioning gear 520 and the tension drum 502 move axially.

[0103] The axial position of the tension drum 502 relative to the chassis surface 524 depends on the rotational position of the tension gear 520 relative to the chassis surface 524. When the tension gear 520 rotates in the first direction 526, the length of the path of the flexible tensioning element 504a increases, and the tension present in the flexible tensioning element 504a increases. Because the inclined surface of the ramp 522 abuts the tension gear 520, when the tension gear 520 rotates in the first direction, the tension gear 520 and the tension drum 502 move axially away from the chassis surface 524. Conversely, when the tension gear 520 rotates in the second direction 528, the tension drum 502 and the tension gear 520 move axially toward the chassis surface 524. In this regard, when the tension gear 520 rotates in the second direction 528, the tension present in the flexible tensioning element 504a decreases.

[0104] Although described with respect to a single flexible tensioning element 504a, in some embodiments, as Figure 5A and Figure 5B As shown, the tensioning drum 502 is positioned to engage with a plurality of flexible tensioning elements 504a-504d. In this regard, axial movement of the tensioning drum 502 changes the path of each flexible tensioning element 504a-504d. In some embodiments, as shown Figure 5AAs shown, in addition to the drive component 506 being driven to operate the dynamic tensioner 500, the drive component 530 is driven to apply a load to the flexible tensioning element 504a, for example, to steer the distal end component. As described herein, the drive system of the remotely controllable manipulator can drive the drive component 530. In some cases, the drive component 530 is coupled to multiple flexible tensioning elements, such as flexible tensioning elements 504a, 504b. When the drive component 530 is driven, the drive component 530 applies tension to one of the flexible tensioning elements 504a, 504b while releasing tension on the other of the flexible tensioning elements 504a, 504b. The load applied to the flexible tensioning elements 504a, 504b controls the movement of the distal end component along a single degree of freedom, for example. In some examples, drive component 530 drives flexible tensioning element 504b, causing flexible tensioning element 504a to relax when flexible tensioning element 504b is driven, and causing flexible tensioning element 504b to relax when flexible tensioning element 504a is driven. The preload tension applied to flexible tensioning elements 504a, 504b by dynamic tensioner 500 is sufficiently large that flexible tensioning elements 504a, 504b relax but do not become slack during operation of drive component 506.

[0105] The drive component 506 is, for example, a capstan that can be rotated by an actuator of the manipulator's drive system. In some embodiments, the torque on the capstan is determined, for example, by the controller 117 based on the current applied to the actuator to rotate the capstan. The controller 117 then determines the force applied by the tension drum 502 on the flexible tensioning element 504a.

[0106] In some examples of a dynamic tensioner, the dynamic tensioner includes a spring to apply a static preload tension to the flexible tensioning element. The static preload tension is, for example, a non-adjustable preload tension applied to the flexible tensioning element that maintains the relative positions, e.g., mechanical integrity, of components of a surgical instrument. During a surgical procedure, the dynamic tensioner is operated to set an adjustable preload tension to the flexible tensioning element, which is in addition to the preload tension caused by the spring. In some embodiments, the spring is configured such that forces on the dynamic tensioner from the flexible tensioning element (e.g., due to a load applied to the flexible tensioning element to steer the distal component) are not absorbed by the spring. When an actuation tension load is applied to the flexible tensioning element to steer the distal component, the actuation load on the flexible tensioning element is not absorbed by the spring, but is instead transmitted to the distal component, e.g., to move the distal component. In some cases, the dynamic tensioner, when operated, compresses the spring so that the coils of the spring contact one another, such that when the dynamic tensioner is used to apply an adjustable preload tension, the spring is unable to further absorb the force applied by the flexible tensioning element during steering of the distal component. Similarly, in some cases, the dynamic tensioner, when operated, causes the spring to disengage from a portion of the dynamic tensioner (e.g., a portion resting against the flexible tensioning element), such that the force of the flexible tensioning element on that portion of the dynamic tensioner is not absorbed by compression of the spring.

[0107] Reference Figure 5E In examples of a dynamic tensioner 500 that includes a tensioning drum 502 , in some examples, the dynamic tensioner 500 includes a spring 532 that applies a static preload tension. Figure 5E The spring 532 is shown in a deployed position, wherein the spring 532 applies a static preload tension to the flexible tensioning element. For example, the spring 532 is positioned between the tensioning drum 502 and the tensioning gear 520. When the tensioning gear 520 rotates, the tensioning gear 520 advances toward the tensioning drum 502 to compress the spring 532. Figure 5F , spring 532 is shown in a compressed position. During movement of the tensioning drum 502, the tensioning gear 520 compresses the spring 532 beyond its linear elastic range, e.g., causing the coils of the spring 532 to contact one another. When the spring 532 is compressed in this manner, the static preload tension in the flexible tensioning element 504a caused by the spring 532 is not increased by axial movement of the tensioning drum 502 to increase the adjustable preload tension. When the coils of the spring 532 contact one another, the tensioning drum 502 moves to change the path of the flexible tensioning element 504a.

[0108] refer to Figure 6, in some embodiments, the dynamic tensioner 600 includes a lead screw 602 that is rotatable to adjust the path of a flexible tensioning element. The dynamic tensioner 600 includes an arm 604 having a first end 606 coupled to the lead screw 602. The first end 606 of the arm 604 is movable, for example, along the longitudinal axis of the lead screw 602. A nut 607, movable axially along the lead screw 602, couples the lead screw 602 to the first end 606 of the arm 604. A second end 608 of the arm 604 includes a guide 610 that includes a hole 612 through which the flexible tensioning element extends. The arm 604 is pivotally mounted to a chassis 614 of the surgical instrument at a pin 616.

[0109] For example, the lead screw 602 is coupled to a drive component to be driven by a drive system of a manipulator to which the surgical instrument is mounted. An input load (e.g., torque) applied to the lead screw 602 causes the arm 604 to rotate relative to the chassis, for example, causing the arm 604 to pivot about a pin 616 on the chassis. When driven, the lead screw 602 rotates. In some embodiments, the nut 607 moves axially as the lead screw 602 rotates, thereby causing the first end 606 of the arm 604 to rotate about the pin 616. The pivoting motion of the arm 604 then moves the second end 608 of the arm 604. In particular, the second end 608 rotates, thereby adjusting the path of a flexible tensioning element (not shown) passing through a guide 610. The guide 610, for example, abuts the flexible tensioning element, such that movement of the guide 610 causes the path of the flexible tensioning element to be adjusted. Rotating the lead screw 602 to adjust the path of the flexible tensioning element increases the tension in the flexible tensioning element. In some cases, arm 604 applies tension to the flexible tensioning element that increases non-linearly with torque applied to lead screw 602 .

[0110] The flexible tensioning elements are attached, for example, to the drive member 603a. In some cases, multiple flexible tensioning elements are attached to the drive member 603a and pass through holes 612 in the guide 610. The arm 604, when pivoted, causes the guide 610 to pivot and move proximally away from the distal member, thereby adjusting the path of each flexible tensioning element. When rotated, the lead screw 602 applies a preload tension to each flexible tensioning element by manipulating the guide 610. In some embodiments, another set of flexible tensioning elements is attached to the drive member 603b. When pivoted, the guide 610 adjusts the path of each flexible tensioning element. In some cases, a first set of flexible tensioning elements attached to the drive member 603a controls movement of the distal member in one degree of freedom, and a second set of flexible tensioning elements attached to the drive member 603b controls movement of the distal member in another degree of freedom.

[0111] In some examples of a dynamic tensioner, the dynamic tensioner is driven by a drive component that, when operated, causes movement of the distal member along the degrees of freedom. For example, the drive component is a multifunctional drive component that is actuatable to apply an adjustable preload tension and also actuatable to apply a load to steer the distal member. In this case, the manipulator to which the surgical instrument is mounted does not require a drive input to actuate the dynamic tensioner independently of the drive input that steers the distal member on the surgical instrument.

[0112] Figure 7A An assembly for mounting a tubular member 704 of a surgical instrument to a chassis of the surgical instrument (e.g., mounting tubular member 115 to chassis 102) is depicted. The assembly includes an assembly housing 701 housing an example of a dynamic preload tensioner 700. In some cases, assembly housing 701 is part of the chassis of the surgical instrument. Dynamic tensioner 700 is associated with a mechanism for controlling movement of a distal component along a roll degree of freedom (e.g., rotation of the distal component about a longitudinal axis 710 of tubular member 704). In some examples, the roll drive mechanism of the surgical instrument includes a gear 702 that, when driven, is rotationally coupled to the tubular member 704 of the distal component. The distal component rotates in response to rotation of the tubular member 704, e.g., rolls about the longitudinal axis 710 of the tubular member 704. Gear 702 is driven by a drive component, e.g., coupled to a drive system of a manipulator.

[0113] Also refer to Figure 7B Dynamic tensioner 700 includes a rotatable member 706. When gear 702 is rotated to a predefined orientation, gear 702 engages rotatable member 706, causing rotatable member 706 to rotate relative to assembly housing 701, for example, about longitudinal axis 710 of tubular member 704. As rotatable member 706 rotates relative to assembly housing 701, it moves along longitudinal axis 710. As rotatable member 706 rotates, gear 702 and tubular member 704 move axially. As tubular member 704 moves axially, the distal component moves axially.

[0114] As described herein, tubular member 704 supports the distal component and includes a portion of the path of a flexible tensioning element 707 coupled to the distal component. In this regard, when tubular member 704 is moved axially distally, the path of flexible tensioning element 707 changes, e.g., the length of the path increases. Specifically, in response to the axial movement of tubular member 704, the distal component moves away from assembly housing 701, thereby lengthening the path of flexible tensioning element 707. Specifically, the length of the portion of the path of flexible tensioning element 707 between assembly housing 701 and the distal component is extended due to the axial movement of tubular member 704. Rotating rotatable member 706 thus causes tension to be applied to flexible tensioning element 707.

[0115] In some embodiments, when the rotatable member 706 rotates, it follows a ramp 708 (e.g., a spiral path), causing the rotatable member 706 to move along the longitudinal axis 710. In some examples, the ramp 708 is formed on a delimiting member 712 in the assembly housing 701. The rotatable member 706 can rotate relative to the delimiting member 712. The delimiting member 712 includes a delimiting portion 709 that, when engaged with the rotatable member 706, inhibits further rotation of the rotatable member 706. The rotatable member 706 rotates about the longitudinal axis 710 along the ramp 708 and then contacts the delimiting portion 709, which inhibits further rotation of the rotatable member 706. Because the rotatable member 706 is rotated by the gear 702 that is driven to roll the distal component, the delimiting portion 709, when engaged with the rotatable member 706, inhibits rotation of the gear 702 and thereby inhibits further tumbling movement of the distal component, such as rotation of the distal component about the longitudinal axis 710 of the tubular member 704.

[0116] In some embodiments, the rotatable member 706 is movable between a first axial position 714 and a second axial position 716. As the rotatable member 706 moves from the first axial position 714 (proximal) to the second axial position 716 (distal), the tubular member 704 moves axially. The axial movement of the tubular member 704 to the second axial position 716 extends the path of the flexible tensioning element 707. In some embodiments, when the rotatable member 706 is in the first axial position 714, an initial preload tension is applied to the flexible tensioning element 707, and when the rotatable member 706 is in the second axial position 716, an operational preload tension greater than the initial preload tension is applied to the flexible tensioning element 707. The operational preload tension is, for example, a preload tension that facilitates a one-to-one transfer of an actuation tension load from the proximal end of the flexible tensioning element 707 to the distal end of the flexible tensioning element 707 (e.g., to a distal component).

[0117] In some cases, the rotatable member 706 can be locked to the delimiting member 712. When the rotatable member 706 is moved to the second axial position 716, the rotatable member 706 can, for example, be locked to the delimiting member 712. The rotatable member 706 includes, for example, a locking portion 715 that engages a corresponding locking portion 717 of the delimiting member 712. When the locking portion 715 of the rotatable member 706 engages the corresponding locking portion 717 on the delimiting member 712, the rotatable member 706 is locked to the delimiting member 712, such that further rotation of the rotatable member 706 is inhibited. Although a first position and a second position are described, in other embodiments, the rotatable member 706 can be locked into one of a plurality of discrete positions. In this regard, depending on the selected discrete position of the rotatable member 706, one of a plurality of discrete preload tensions is applied to the flexible tensioning element 707.

[0118] In some embodiments, gear 702 can rotate within a first predefined range to roll the distal component. Gear 702 can also rotate beyond the first predefined range to a second predefined range. When gear 702 rotates within the second predefined range, gear 702 engages rotatable member 706 to rotate rotatable member 706 relative to delimiting member 712. In this regard, when gear 702 rotates within the first predefined range, gear 702 does not rotate rotatable member 706. The first predefined range is, for example, 180 degrees. For example, gear 702 rotates 90 degrees clockwise and 90 degrees counterclockwise from its initial position. The second predefined range is, for example, 20 to 40 degrees beyond the first predefined range. For example, when gear 702 rotates within the second predefined range, gear 702 rotates 20 to 40 degrees beyond the first predefined range.

[0119] In some cases, the first predefined range is a controller-enforced range. In some cases, the controller (e.g., controller 117) inhibits the gear 702 from moving beyond the first predefined range after the gear 702 rotates, such that the rotatable member 706 is locked in the second axial position 716 to apply the preload tension.

[0120] In some embodiments where the rotatable member 706 is lockable to the delimiting member 712, when the rotatable member 706 is locked to the delimiting member 712, the gear 702 moves from the second predefined range back to the first predefined range, so that the gear 702 can be driven to roll the distal component. As a result, the gear 702 can be driven to cause the distal component to roll while a preload tension is applied to the flexible tensioning element 707.

[0121] Reference Figure 7CIn some implementations, the gear 702 contacts the first lateral portion 718 of the rotatable member 706 to rotate the rotatable member 706 from the first position toward its second position. The gear 702 contacts the second lateral portion 720 of the rotatable member 706 to rotate the rotatable member 706 back from the second position toward the first position. In such examples, the gear 702 engages the rotatable member 706 to reposition the rotatable member 706 toward the second position to apply the operating preload tension to the flexible tension member 707. The gear 702 is also able to engage the rotatable member 706 to move the rotatable member back toward the first position such that the preload tension is released.

[0122] Figure 8 Another example of a dynamic preload tensioner 800 is depicted. The dynamic tensioner 800 includes a rotatable cam 802. The rotatable cam 802 is coupled to a drive component of a surgical instrument, for example, such that the rotatable cam 802 rotates when the drive component is driven. In some cases, the rotatable cam 802 rotates relative to a chassis of the surgical instrument. As the rotatable cam 802 rotates, a surface 804 of the rotatable cam 802 engages a flexible tension member 806b to change a path of the flexible tension member 806b. In some implementations, as the rotatable cam 802 rotates, the surface 804 of the rotatable cam 802 engages each of a plurality of flexible tension members 806a-806d (i.e., for any angle of rotation of the cam, the shape of the cam surface that engages elements 806a and 806d results in the same change in path length as the shape of the cam surface that engages elements 806b and 806c causes). The rotatable cam 802 exerts a transverse load on the flexible tension members 806a-806d to deflect the flexible tension members 806a-806d, thereby adjusting the path of the flexible tension members 806a-806d. In some cases, the surface 804 of the rotatable cam 802 is elliptical.

[0123] FIG. 9 depicts an example of a dynamic preload tensioner 900 that includes a tension plate 902 pivotably mounted to a chassis 904 of a surgical instrument. The tension plate 902 is rotatable about a pin 905 on the chassis 904, for example. As the tension plate 902 rotates relative to the chassis 904, the path of a flexible tension member changes.

[0124] In some implementations, the flexible tension member passes from the universal joint 910 inward and through a hole in the tension plate 902, and then into a tubular member 912 to a distal component of the surgical instrument. The flexible tension member abuts a side of the hole in the tension plate 902, and as the tension plate 902 rotates upward, the point at which the tension member abuts the side of the hole moves upward, thus the path of the flexible tension member is adjusted.

[0125] In some embodiments, the flexible tensioning element passes through a universal joint. In this respect, the universal joint changes the path length as it rotates and thus applies the actuation tension to the desired tensioning element.

[0126] In some embodiments, rather than passing through universal joint 910, the flexible tensioning element is connected to universal joint 910. In this regard, as universal joint 910 rotates, the proximal end of the flexible tensioning element moves away from the distal member, thereby increasing the length of the path of the tensioning element required to actuate the distal member.

[0127] Regardless of whether the flexible tensioning element passes through or is connected to the universal joint 910, the dynamic preload tensioner 900 can be operated to adjust the path of the flexible tensioning element and adjust the preload tension on the tensioning element. To rotate the tensioning plate 902 about the pin 905, the dynamic tensioner 900 includes, for example, Figure 9B 905, engaging a rotatable member 914 with tensioning plate 902. As rotatable member 914 rotates, a ramp formed on rotatable member 914 engages tensioning plate 902, causing tensioning plate 902 to pivot about pin 905, thereby extending the path of the flexible tensioning element. In some cases, a drive component 915 of the surgical instrument is driven by the manipulator's drive system to rotate rotatable member 914.

[0128] In some embodiments, to steer the distal component, a drive system, such as a manipulator, operates lead screws 916a, 916b, and 916c. When operated, lead screws 916a, 916b, and 916c rotate arms 918a, 918b, and 918c, respectively, causing gimbal 910 to pivot relative to chassis 904. As gimbal 910 pivots, gimbal 910 abuts against a flexible tensioning element to adjust the path of the flexible tensioning element, thereby subjecting the flexible tensioning element to tension. Multiple flexible tensioning elements can be driven by lead screws 916a, 916b, and 916c to move the distal component with multiple degrees of freedom. Alternatively or additionally, the drive system drives gear system 920 to roll the distal component.

[0129] A number of embodiments have been described, however, it will be understood that various modifications may be made.

[0130] In some embodiments, a preload tension applied to a flexible tensioning element is controlled during a surgical procedure. For example, while a distal member is being steered during a surgical procedure using a subset of drive outputs of a manipulator's drive system, another drive output can be operated to adjust the preload tension applied to the flexible tensioning element without steering the distal member. The surgical instrument includes one of the dynamic preload tensioners described herein, for example, and applies the preload tension before the distal member is steered for surgical purposes.

[0131] In some embodiments, the pre-load tension is adjusted during a surgical procedure when the load applied to the distal component varies during the surgical procedure. For example, the pre-load tension is increased when the load on the distal component increases due to contact with patient tissue. Where the load on the distal component is lower, for example, when the distal component is steered in space without contact with patient tissue, the dynamically adjustable pre-load tension is decreased. In some embodiments, the surgical instrument is a surgical stapler system and the dynamically adjustable pre-load tension is increased when the stapler system is to be clamped.

[0132] In some embodiments, a dynamic pre-load tensioner for a flexible tensioning element includes a drive component operable to steer a distal component by using the flexible tensioning element. The flexible tensioning element is, for example, twisted to change the path of the flexible tensioning element. In some embodiments, the dynamic pre-load tensioner includes a first portion having a first diameter and a second portion having a second diameter, the first diameter being smaller than the second diameter. The flexible tensioning element is, for example, wound around the first portion and the second portion. Figure 10 In the illustrated example, the dynamic pre-load tensioner 1000 includes a first portion 1004 and a second portion 1006. The dynamic tensioner 1000 is, for example, a rotatable winch, where the first portion 1004 has a first diameter and the second portion 1006 has a second diameter, the first diameter being smaller than the second diameter. At a distal end, the flexible tensioning element 1008 is attached to a distal component. At a proximal end, the flexible tensioning element 1008 is attached to the dynamic tensioner 1000 so that it can be driven by the dynamic tensioner 1000 and so that it can be selectively wound around the different portions 1004, 1006. The dynamic tensioner 1000 includes a drive component 1010, for example, drive component 104a, which can be driven to apply tension to the flexible tensioning element 1008 to steer the distal component to which the flexible tensioning element 1008 is coupled.

[0133] When the drive assembly 1010 is driven by a drive system such as a manipulator, the dynamic tensioner 1000 rotates. To steer the distal assembly, the dynamic tensioner 1000 rotates to apply tension to the flexible tensioning element 1008. To apply an adjustable preload tension to the flexible tensioning element 1008, the flexible tensioning element 1008 is wrapped around a selected portion of a capstan. As the flexible tensioning element 1008 is wrapped around the second portion 1006, the path of the flexible tensioning element 1008 is adjusted so that the preload tension is applied to the flexible tensioning element 1008. In some cases, in the initial state of the surgical instrument, the flexible tensioning element 1008 is wrapped around the first portion 1004. To add preload tension to the flexible tensioning element, the flexible tensioning element 1008 is wrapped around the second portion 1006. In some cases, to add preload tension to flexible tensioning element 1008, flexible tensioning element 1008 is moved from an initial state in which it is wrapped around first portion 1004 to an operational state in which it is wrapped around both first portion 1004 and second portion 1006. In some embodiments, if flexible tensioning element 1008 is actuated to move the distal effector along a degree of freedom in a first direction, and another flexible tensioning element is actuated to move the distal effector along a degree of freedom in a second direction, the other flexible tensioning element is attached to a separate actuation component and the dynamic tensioner.

[0134] like Figure 11A and Figure 11B As shown, in some embodiments, a dynamic preload tensioner 1100 includes a horizontal portion 1102 having an ellipsoidal, oval, and / or non-circular profile, rather than having multiple portions with different diameters. The dynamic tensioner 1100 is mounted to a chassis of a surgical instrument such that the dynamic tensioner 1100 is rotatable about a center of rotation 1104. A drive assembly (not shown) can be driven by a drive system of a surgical manipulator as described above to rotate the dynamic preload tensioner 1100. The horizontal portion 1102 includes, for example, a first region 1106 and a second region 1108. The first region 1106 has a profile whose distance from the center of rotation 1104 varies along its length. For example, the second region 1108 has a circular profile with a constant distance between the profile and the center of rotation 1104 of the horizontal portion 1102.

[0135] A flexible tensioning element 1110 is attached to the dynamic tensioner 1100 so that it wraps around the horizontal portion 1102 of the capstan. To add preload tension to the flexible tensioning element 1110, the flexible tensioning element 1110 is wrapped around a first region 1106. As the flexible tensioning element 1110 wraps around the first region 1106, the path of the flexible tensioning element 1110 changes, e.g., the length of the path decreases. In an initial operation, the flexible tensioning element 1110 wraps around the first region 1106 to increase the preload tension from a first value to a second value. In an operating state in which the preload tension has been added to the flexible tensioning element 1110, the flexible tensioning element 1110 wraps around both the first region 1106 and the second region 1108. The flexible tensioning element 1110 begins extending away from the dynamic tensioner 1100 at the second region 1108, such that the length of the flexible tensioning element 1110 wrapped around the dynamic tensioner 1100 is proportional to the rotation of the dynamic tensioner 1100. Conversely, as the flexible tensioning element 1110 extends away from the dynamic tensioner 1100 from the first region, a greater length of the flexible tensioning element is wound onto the dynamic tensioner 1100 for a given amount of rotation of the dynamic tensioner 1100. The dynamic tensioner 1100 rotates to drive the flexible tensioning element from the initial state to the operational state. In some embodiments, if the flexible tensioning element 1110 is driven to move the distal end effector in a first direction along a degree of freedom, and another flexible tensioning element is driven to move the distal end effector in a second direction along a degree of freedom, the other flexible tensioning element is attached to a separate drive component and the dynamic tensioner.

[0136] While the manipulator's drive system has been described as operating a dynamic preload tensioner, in some embodiments, a manually operable preload tensioning tool, such as one operated by a nurse, clinician, or surgeon, operates the dynamic tensioner. The tensioning tool, for example, is a switch, knob, or other device on an outer surface of a chassis of the surgical instrument, and the operator manually operates the dynamic tensioner to adjust the path of the flexible tensioning element. When operated, the tensioning tool can be locked in position so that the preload tension provided by the adjustable path of the flexible tensioning element is maintained. In some cases, the tensioning tool is coupled to the mechanism for the dynamic tensioner described in the examples herein. For example, the tensioning tool replaces the drive component, such that the preload tension is applied by manual operation of the tensioning tool rather than by operation of an actuator coupled to the drive component.

[0137] In some embodiments, a dynamic preload tensioner includes a pin movably mounted to a chassis and engageable with a flexible tensioning element to change the path of the flexible tensioning element when the pin moves relative to the chassis. For example, the pin applies a transverse load to the flexible tensioning element, which causes the flexible tensioning element to bend at the location where the pin contacts the flexible tensioning element. This bending of the flexible tensioning element changes the path of the flexible tensioning element, for example, increasing the path length. Thus, the change in path adds preload tension to the flexible tensioning element.

[0138] Examples presented herein demonstrate that a dynamic tensioner can be locked in certain circumstances, allowing the preload tension applied using the dynamic tensioner to be maintained. In some embodiments, the dynamic tensioner can be locked in one of several discrete positions. For example, the dynamic tensioner includes a ratchet mechanism that, when advanced, applies preload tension to the flexible tensioning element. In some cases, the ratchet mechanism can be reset to reduce the preload tension on the flexible tensioning element.

[0139] In some embodiments, the dynamic preload tensioner rotates the tubular member relative to the chassis. Figure 1 , an alternative dynamic tensioner rotates tubular member 115 relative to chassis 102 about the point at which tubular member 115 and chassis 102 are connected. At the location where flexible tensioning element 106 enters tubular member 115, surgical instrument 101 includes, for example, a bearing surface that flexible tensioning element 106 engages when tubular member 115 rotates relative to chassis 102. The engagement between the bearing surface and flexible tensioning element 106 changes the path of flexible tensioning element 106, for example, increasing the path length.

[0140] In some embodiments, preload tension is added to the flexible tensioning element only when a surgical instrument is mounted to the manipulator. For example, the controller operates the drive system of the manipulator only upon detecting that the surgical instrument has been mounted to the manipulator. In some cases, a slave interface assembly of the manipulator engages an actuator rod on the surgical instrument. The actuator rod, when actuated, activates a dynamic preload tensioner to add preload tension to the flexible tensioning element. In some embodiments, the slave interface assembly of the manipulator includes a sensor for detecting engagement with the surgical instrument. Upon detecting engagement of the slave interface assembly of the manipulator with the surgical instrument, the sensor sends a signal to the controller, which in turn operates an actuator to drive a drive component coupled to the dynamic tensioner.

[0141] While lock mechanisms and techniques have been described with respect to some embodiments, in some cases, a controller of the manipulator operates a drive output to maintain a position of a dynamic tensioner and thus a preloaded tension in the flexible tensioning element. In cases where the dynamic tensioner is coupled to a drive component that is driven by the drive output of the manipulator, the controller locks the actuator to inhibit rotation of the drive component. For example, the controller locks the actuator in response to determining that the tension in the flexible tensioning element is above a predefined threshold.

[0142] Thus, other embodiments are within the scope of the following claims.

Claims

1. A surgical instrument comprising: a chassis located at the proximal end; a distal component located at the distal end; a tubular member coupled to the chassis and extending between the chassis and the distal member, the tubular member having a longitudinal axis; a drive component mounted in the chassis; a flexible tensioning element coupled to the drive member, extending through the tubular member, and coupled to the distal member; a first rotatable member configured to be rotated to cause rotation of the tubular member and the distal component; and a dynamic preload tensioner comprising a second rotatable member engaged with the tubular member, the second rotatable member engaged with the first rotatable member and movable along the longitudinal axis in response to rotation of the first rotatable member, the dynamic preload tensioner being configured to move the tubular member along the longitudinal axis of the tubular member and relative to the chassis to change a path of the flexible tensioning element in response to movement of the second rotatable member along the longitudinal axis.

2. The surgical instrument of claim 1 , wherein: The dynamic preload tensioner is located on the proximal end of the tubular member.

3. The surgical instrument of claim 1, wherein the flexible tensioning element extends through the first rotatable member.

4. The surgical instrument of claim 1 , wherein: The first rotatable member includes a gear portion.

5. The surgical instrument of claim 3, wherein: In a position in which the first rotatable member is rotated to a predefined orientation, the first rotatable member engages the second rotatable member; and Movement of the second rotatable member along the longitudinal axis of the tubular member and relative to the chassis causes the first rotatable member to move axially relative to the chassis.

6. The surgical instrument of claim 1 , wherein: When the second rotatable member rotates relative to a portion of the chassis, the second rotatable member is movable along a slope formed on the portion of the chassis.

7. The surgical instrument of claim 1 , wherein: The second rotatable member includes a locking portion configured to engage a corresponding locking portion on a portion of the chassis to lock the position of the second rotatable member.

8. The surgical instrument of claim 7, wherein: The second rotatable member is lockable into one of a plurality of discrete positions.

9. The surgical instrument according to any one of claims 1, 6 and 7, wherein: The first rotatable member is configured to engage the second rotatable member to cause the second rotatable member to move from a first axial position to a second axial position to change the path of the flexible tensioning element, and the first rotatable member is further configured to engage the second rotatable member to move the second rotatable member from the second axial position to the first axial position.

10. The surgical instrument according to any one of claims 1 to 7, wherein: Rotation of the first rotatable member within a first predefined range causes rotation of the tubular member and the distal component, and Rotation of the first rotatable member within a second predefined range causes distal movement of the tubular member and the distal component to change the path of the flexible tensioning element.

11. The surgical instrument according to any one of claims 1 to 7, wherein: Movement of the second rotatable member along the longitudinal axis includes movement of the second rotatable member along a helical path.

12. A method of controlling preload tension in the surgical instrument of claim 1, the method comprising: moving the second rotatable member along the longitudinal axis to cause the tubular member to move along the longitudinal axis of the tubular member and relative to the chassis to adjust tension to a predefined preload tension in the flexible tensioning element of the surgical instrument; and In response to detecting the predefined preload tension in the flexible tensioning element, the position of the tubular member is maintained by maintaining the position of the second rotatable member.

13. The method according to claim 12, wherein: Moving the second rotatable member includes rotating the second rotatable member relative to the chassis of the surgical instrument.

14. The method of claim 12, further comprising moving the distal component of the surgical instrument while maintaining the position of the tubular member.

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