Pulley assembly for articulating surgical instruments

Abstract

The present invention relates to a pulley device for articulating surgical instruments. The robotic surgical instrument comprises: a shaft; an end effector element; an articulation portion, the articulation portion connecting the end effector element to the shaft, the articulation portion comprising: a first joint that can be driven by a first pair of drive elements, the first joint allowing the end effector element to rotate around a first axis transverse to the longitudinal axis of the shaft; and a second joint that can be driven by a second pair of drive elements; and a pulley device, the second pair of drive elements being constrained to move around the pulley device, the pulley device comprising: a first group of pulleys that can rotate around the first axis; and a second group of pulleys that are positioned relative to the first group of pulleys so that at the extreme rotation angle, the second pair of drive elements maintain contact with both the first group of pulleys and the second group of pulleys.

Description

[0001] This application is a divisional application of a patent application with an international application date of December 9, 2016, application number 201680071617.X (PCT / GB2016 / 053900), and invention name “Pulley device for articulated surgical instruments”. Technical Field

[0002] The present application relates to a pulley assembly for articulating a surgical instrument. Background Art

[0003] It is known to use robots to assist and perform surgery. Figure 1 A typical surgical robot 100 is illustrated, consisting of a base 108, an arm 102, and an instrument 105. The base supports the robot and is itself rigidly attached to, for example, an operating room floor, an operating room ceiling, or a cart. The arm extends between the base and the instrument. The arm is articulated with a plurality of flexible joints 103 along its length, which are used to position the surgical instrument in a desired position relative to the patient. The surgical instrument is attached to the distal end 104 of the robot arm. The surgical instrument punctures the body of the patient 101 at a port 107 to access the surgical site. At its distal end, the instrument includes an end effector 106 that performs the medical procedure.

[0004] Figure 2 A typical surgical instrument 200 for performing robotic laparoscopic surgery is illustrated. The surgical instrument includes a base 201 by which the surgical instrument is connected to a robotic arm. A shaft 202 extends between the base 201 and an articulation 203. The articulation 203 terminates in an end effector 204. Figure 2 , a pair of serrated jaws are illustrated as end effector 204. Articulation 203 allows end effector 204 to move relative to shaft 202. It is desirable to provide at least two degrees of freedom to the movement of end effector 204 by means of the articulation.

[0005] Figure 3 An example of a known surgical instrument 300 is illustrated in which an end effector 204 is allowed to move relative to an axis 202 by means of a pitch joint 301 and two yaw joints 302. Joint 301 enables the end effector 204 to rotate about a pitch axis 303. Joint 302 enables each jaw of the end effector 204 to rotate about a yaw axis 304. The joints are driven by cables 306, 307 and 308. Pulley 305 is used to guide cables 307 and 308 from their channels across the pitch joints to the yaw joints. Pulley 305 is offset from the central axis of the articulated portion 203. The outer diameter of the shaft is 8 mm in order to accommodate the number, size and position of the internal elements of the articulated portion.

[0006] It is desirable to reduce the outer diameter of the instrument in order to minimize the size of the incision through the patient's skin and minimize rupture within the patient's body. It is also desirable to minimize the weight of the surgical instrument in order to minimize the size and weight of the robot base and arms required to support the instrument, thereby making the robot overall more compact and thus occupying less space in the operating room and being able to move more within the operating room.

[0007] In a typical laparoscopic procedure, the surgeon utilizes many instruments and therefore changes from one instrument to another many times. Therefore, it is desirable to minimize the time taken and maximize the ease of removing one instrument from the robotic arm and attaching a different instrument. Additionally, it is desirable to minimize the time taken to set up the instrument ready for use once it has been attached to the robotic arm. Summary of the invention

[0008] According to one aspect of the present invention, a robotic surgical instrument is provided, which includes: a shaft extending between an instrument interface located at one end and an articulated portion located at the other end; the articulated portion connects a first end effector element to the shaft, the articulated portion including: a first joint that can be driven by a first pair of drive elements, the first joint allowing the first end effector element to rotate around a first axis transverse to the longitudinal axis of the shaft; and a second joint that can be driven by a second pair of drive elements; and a pulley device, the second pair of drive elements being constrained to move around the pulley device, the pulley device including: a first group of pulleys that can rotate around the first axis; and a second group of pulleys, wherein each pulley in the second group of pulleys can rotate around an offset axis that deviates from the first axis in a direction transverse to the longitudinal direction of the shaft, and the second group of pulleys is positioned between the first group of pulleys and the instrument interface end of the shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Now, the present invention will be described by way of example with reference to the accompanying drawings. In the drawings:

[0010] Figure 1 A surgical robot performing a surgical procedure is illustrated;

[0011] Figure 2 A known surgical instrument is illustrated;

[0012] Figure 3 illustrates a known arrangement of an articulated end effector for a surgical instrument;

[0013] Figure 4 The surgical robot is illustrated;

[0014] Figure 5a and Figure 5b The distal end of the surgical instrument is illustrated;

[0015] Figure 6a and Figure 6b Shown in vertical configuration Figure 5a and Figure 5b A pulley device at the distal end of the surgical instrument;

[0016] Figure 7 Shown in various non-straight configurations Figure 5a and Figure 5b A pulley device at the distal end of the surgical instrument;

[0017] Figure 8 Pictured Figure 5a and Figure 5b An offset pulley of the pulley arrangement shown in;

[0018] Fig. 9 A non-straight configuration of the distal end of the surgical instrument is illustrated;

[0019] Fig.10 The support body and redirection pulley of the hinged portion of the surgical instrument are illustrated;

[0020] Fig.11 Pictured Fig.10 Different views of the support body and redirection pulley;

[0021] Fig.12 and Fig.13 Separately illustrated Fig.10 and Fig.11 A support body for the hinged portion;

[0022] Fig.14 Illustration of installation to Fig.12 and Fig.13 A support body having a redirecting pulley mounted with the main shaft;

[0023] Fig.15 Pictured Fig.11 and Fig.13 The inclined surface and the groove of the support body;

[0024] Fig.16a and Fig.16b The arrangement of the drive element in the instrument shaft is illustrated;

[0025] Fig.17a and Fig.17b Two views of surgical instruments are illustrated;

[0026] Fig.18 The spokes in the shaft of the instrument are illustrated;

[0027] Fig.19a , Fig.19b and Fig.19c Three views of the device interface are illustrated;

[0028] Fig.20a and Fig.20b The tensioning mechanism is illustrated;

[0029] Fig.21a , Figure 21b and Fig.21c Three views of the drive assembly interface of the robot arm are illustrated;

[0030] Fig.22a , Figure 22b and Fig.22c The configuration of the device interface components is illustrated;

[0031] Fig.23 The configuration of the interface elements of the drive assembly is illustrated;

[0032] Fig.24 illustrates an instrument interface engaged in a drive assembly interface; and

[0033] Fig.25 Another view of the instrument interface is illustrated. DETAILED DESCRIPTION

[0034] Figure 4 A surgical robot is illustrated having an arm 400 extending from a base 401. The arm comprises a plurality of rigid limbs 402. The limbs are connected by revolute joints 403. The most proximal limb 402a is connected to the base by joint 403a. It is connected in series with the other limbs by further joints 403. Suitably, a wrist 404 is formed by four separate revolute joints. The wrist 404 connects one limb (402b) of the arm to the most distal limb (402c). The most distal limb 402c carries an attachment 405 for a surgical instrument 406. Each joint 403 of the arm has: one or more motors 407 which can be operated to cause rotational movement at the corresponding joint; and one or more position and / or torque sensors 408 which provide information about the current configuration and / or load at this joint. Suitably, the motors are arranged close to the joints whose movement is driven by the motors to improve weight distribution. For clarity, Figure 4 Only some of the motors and sensors are shown.The arm may be generally described in the applicant's co-pending patent application PCT / GB2014 / 053523.

[0035] The arm terminates in an attachment 405 for docking with an instrument 406. Suitably, the instrument 406 is provided with a Figure 2The form described. The diameter of the instrument is less than 8mm. Suitably, the diameter of the instrument is 5mm. The diameter of the instrument may be less than 5mm. The instrument diameter may be the diameter of the shaft. The instrument diameter may be the diameter of the profile of the hinge. Suitably, the diameter of the profile of the hinge matches or is narrower than the diameter of the shaft. Attachment 405 includes a drive assembly for driving the hinge of the instrument. A movable interface element of the drive assembly interface mechanically engages a corresponding movable interface element of the instrument interface to transmit drive from the robotic arm to the instrument. During a typical surgery, one instrument is replaced with another instrument many times. Therefore, during surgery, the instrument can be attached to and removed from the robotic arm. Features of the drive assembly interface and the instrument interface facilitate their alignment when engaged with each other to reduce the accuracy required for the user to align them.

[0036] Instrument 406 includes an end effector for performing the procedure. The end effector may take any suitable form. For example, the end effector may be a smooth jaw, a serrated jaw, a clamp, a pair of scissors, a suture needle, a camera, a laser, a knife, a cutter, a cauterizer, or an aspirator. Figure 2 As described, the instrument includes an articulated portion located between the instrument shaft and the end effector. The articulated portion includes a plurality of joints that allow the end effector to move relative to the instrument shaft. The joints in the articulated portion are actuated by drive elements (such as cables). These drive elements are fixed to interface elements of the instrument interface at the other end of the instrument shaft. Therefore, the robot arm transmits drive to the end effector as follows: movement of the drive assembly interface element causes the instrument interface element to move, which causes the drive element to move, so that the joints of the articulated portion move, and then the end effector moves.

[0037] Controllers for motors, torque sensors, and encoders are assigned to the robot arm. The controllers are connected to a control unit 409 via a communication bus. The control unit 409 includes a processor 410 and a memory 411. The memory 411 stores software executable by the processor in a non-transient manner to control the operation of the motor 407, causing the arm 400 to operate in the manner described herein. In particular, the software can control the processor 410 to cause the motor (e.g., via the assigned controller) to be driven based on inputs from the sensor 408 and the surgeon command interface 412. The control unit 409 is connected to the motor 407 to drive the motor 407 according to the output generated by executing the software. The control unit 409 is connected to the sensor 408 to receive sensed inputs from the sensor, and is connected to the command interface 412 to receive inputs from the command interface. For example, the corresponding couplings may each be an electrical cable or an optical cable, or may be provided by a wireless connection. The command interface 412 includes one or more input devices, whereby the user can request movement of the end effector in a desired manner. For example, the input device can be a manually operable mechanical input device (such as a control handle or joystick), or a contactless input device (such as an optical gesture sensor). The software stored in the memory 411 is configured to respond to these inputs and cause the arm to be powered down and the instrument to move accordingly according to a predetermined control strategy. The control strategy may include a safety feature that regulates the movement of the arm and the instrument in response to the command input. Therefore, in summary, the surgeon at the command interface 412 can control the instrument 406 to move in a manner to perform the desired surgical procedure. The control unit 409 and / or the command interface 412 may be remote from the arm 400.

[0038] Figure 5a and Figure 5b Illustrated are opposing views of the distal end of the surgical instrument. Figure 5a and Figure 5b In the embodiment, the end effector 501 includes a pair of end effector elements 502 and 503. Figure 5a and Figure 5b504. The end effector 501 is depicted as a pair of opposed serrated jaws. It should be understood that this is for illustrative purposes only. The end effector may take any suitable form, such as the form described above. The end effector 501 is connected to the shaft 504 by a hinge 505. The hinge 505 includes a joint that allows the end effector 501 to move relative to the shaft 504. The first joint 506 allows the end effector 501 to rotate around a first axis 510. The first axis 510 is transverse to the longitudinal axis of the shaft 511. The second joint 507 allows the first end effector element 502 to rotate around a second axis 512. The second axis 512 is transverse to the first axis 510. The third joint 513 allows the second end effector element 503 to rotate around the second axis 512. Suitably, the first end effector element 502 and the second end effector element 503 can be independently rotated around the second axis 512 through the second joint and the third joint. The end effector elements can rotate in the same direction or in different directions through the second joint and the third joint. The first end effector element 502 is rotatable about the second axis, while the second end effector element 503 is not rotatable about the second axis. The second end effector element 503 is rotatable about the second axis, while the first end effector element 502 is not rotatable about the second axis.

[0039] Figure 5a and Figure 5b A straight configuration of the surgical instrument is depicted with the end effector aligned with the shaft. In this orientation, the longitudinal axis of the shaft 511 coincides with the longitudinal axis of the articulation and the longitudinal axis of the end effector. The articulation of the first joint, the second joint, and the third joint enables the end effector to assume a range of postures relative to the shaft. Fig. 9 Some configurations of the distal end of the instrument are shown in which the articulation around all of the first, second, and third joints has been adjusted relative to Figure 5a and Figure 5b A vertical configuration is driven.

[0040] Back to Figure 5a and Figure 5b , the distal end of the shaft terminates in a first joint 506. The articulated portion 505 comprises a support 509. At one end, the support 509 is connected to the shaft 504 by a first joint 506. At the other end, the support 509 is connected to the end effector 501 by a second joint 507 and a third joint 513. Thus, the first joint 506 allows the support 509 to rotate relative to the shaft 504 around a first axis 510; and the second joint 507 and the third joint 513 allow the end effector elements 502, 503 to rotate relative to the support 509 around a second axis 512.

[0041] In the figure, both the second joint 507 and the third joint 513 allow rotation around the same axis 512. However, the second joint and the third joint may alternatively allow the end effector elements to rotate around different axes. The rotation axis of one of the end effector elements may deviate from the rotation axis of the other end effector element in the longitudinal direction of the shaft 504. The rotation axis of one of the end effector elements may deviate from the rotation axis of the other end effector element in a direction transverse to the longitudinal direction of the shaft 504. The rotation axis of one of the end effector elements may not be parallel to the rotation axis of the other end effector element. The rotation axes of the end effector elements 502, 503 may deviate from each other in the longitudinal direction of the shaft and / or deviate and / or be at a certain angle in a direction perpendicular to the longitudinal direction of the shaft. This may be desirable because the end effector elements are asymmetric. For example, in an electrosurgical element, a first end effector element may be powered, and a second end effector element is not powered and isolated from the first end effector element. To this end, the rotation axes of the two end effector elements may deviate in a direction perpendicular to the longitudinal direction of the shaft. In another example, the first end effector element may be a blade and the second end effector element is a flat cutting surface.To facilitate use of the blade, the axes of rotation of the two end effector elements may be at an angle to each other.

[0042] The joint of the hinge is driven by a drive element. The drive element is an elongated element extending from the joint in the hinge through the shaft to the instrument interface. Suitably, each drive element can be flexed laterally over its main length at least in those areas of the internal components of the joint and the instrument interface. In other words, each drive element can be flexed in a specified area transverse to its longitudinal axis. This flexibility enables the drive element to be wound around the internal structure of the instrument (such as a joint and a pulley). The drive element can be flexed as a whole transverse to its longitudinal axis. The drive element may not be flexed along its main length. The drive element resists compression and tension applied along its length. In other words, the drive element resists compression and tension acting in the direction of its longitudinal axis. The drive element has a high modulus. The drive element remains taut during operation. The drive element is not allowed to become loose. Therefore, the drive element can transmit the drive from the instrument interface to the joint. The drive element can be a cable.

[0043] Suitably, each joint is driven by a pair of drive elements. Figure 5a and Figure 5b , the first joint 506 is driven by a first pair of drive elements A1, A2. The second joint 507 is driven by a second pair of drive elements B1, B2. The third joint is driven by a third pair of drive elements C1, C2. Suitably, each joint is driven by its own pair of drive elements. In other words, each joint is driven by a dedicated pair of drive elements. Suitably, the joints are independently driven. Figure 5a and Figure 5b As shown in the third pair of drive elements in FIG, a pair of drive elements can be constructed as a single component. In this case, the single component is fixed to the joint at one point. For example, the third pair of drive elements C1, C2 includes a ball feature 520 fixed to the third joint 513. This ensures that when the pair of drive elements is driven, the drive is transmitted to the movement of the joint around its axis. Alternatively, a pair of drive elements can be constructed as two components. In this case, each separate component is fixed to the joint.

[0044] Figure 5a and Figure 5b The surgical instrument further includes a pulley arrangement around which the second pair of drive elements and the third pair of drive elements are constrained to move. Figure 6a and Figure 6b The pulley arrangement is better illustrated. The support 509 is Figure 6a and Figure 6b 506. The pulley arrangement further comprises a second set of pulleys 602. The pulley arrangement further comprises a pair of redirecting pulleys 603.

[0045] Figure 7 The pulley arrangement is more clearly shown. The support body, the first joint and the first pair of drive elements have all been removed from the Figure 7 510. The third axis 703 deviates from the first axis 510 in both the longitudinal direction of the shaft and the direction transverse to the longitudinal direction of the shaft. The second pulley 702 can rotate around a fourth axis 704 parallel to the first axis 510. The fourth axis 704 deviates from the first axis 510 in both the longitudinal direction of the shaft and the direction transverse to the longitudinal direction of the shaft. The third axis and the fourth axis are parallel but deviate from each other. The third axis 703 and the fourth axis 704 are located in the same plane perpendicular to the longitudinal direction of the shaft. Figure 8 The distal end of the surgical instrument is illustrated from a different view, more clearly showing the offset axis of the first pulley 701 and the second pulley 702 of the second set of pulleys. By offsetting the first pulley 701 and the second pulley 702, the drive element wound around each pulley can extend along the axis after being wound around the pulleys. Figure 6aAs shown, the first pulley 701 and the second pulley 702 of the second pulley set 602 are located on opposite sides of the first joint 506 in the longitudinal direction of the shaft 504. The first pulley 701 and the second pulley 702 are located on opposite sides of the first pair of driving elements A1, A2.

[0046] The second set of pulleys is located between the first set of pulleys and the instrument interface end of the shaft. Suitably, the second set of pulleys is located within the shaft as shown in the figure. Alternatively, the second set of pulleys may be located within the hinge between the first joint 506 and the second joint 507. However, by positioning the second set of pulleys at the distal end of the shaft 508, the distance between the first joint and the second joint is reduced, thereby reducing the stiffness of the support body 509 required to maintain accurate positioning of the end effector 501, compared to the alternative arrangement of positioning the second set of pulleys in the hinge.

[0047] The first pulley group 601 includes a first pulley 705 and a second pulley 706. Both the first pulley 705 and the second pulley 706 rotate around the first axis 510. The first pulley 705 and the second pulley 706 of the first pulley group are located on opposite sides of the first joint 506 in the longitudinal direction of the shaft 504. The first pulley 705 and the second pulley 706 are located on opposite ends of the first axis 510. The first pulley 705 and the second pulley 706 are located on opposite sides of the first pair of drive elements A1, A2.

[0048] The second pair of drive elements B1, B2 is constrained to move around opposite sides of the first pulley 705 and the second pulley 706 of the first set of pulleys 601. The second pair of drive elements B1, B2 is constrained to move around opposite sides of the first pulley 701 and the second pulley 702 of the second set of pulleys 601. The second pair of drive elements is constrained to move around opposite sides of the first pulley 705 of the first set of pulleys 601 and the first pulley 701 of the second set of pulleys 602. The second pair of drive elements is constrained to move around opposite sides of the second pulley 706 of the first set of pulleys 601 and the second pulley 702 of the second set of pulleys 602.

[0049] The third pair of drive elements C1, C2 is constrained to move around opposite sides of the first pulley 705 and the second pulley 706 of the first set of pulleys 601. The third pair of drive elements C1, C2 is constrained to move around opposite sides of the first pulley 701 and the second pulley 702 of the second set of pulleys 601. The third pair of drive elements is constrained to move around opposite sides of the first pulley 705 of the first set of pulleys 601 and the first pulley 701 of the second set of pulleys 602. The third pair of drive elements is constrained to move around opposite sides of the second pulley 706 of the first set of pulleys 601 and the second pulley 702 of the second set of pulleys 602.

[0050] The second pair of drive elements and the third pair of drive elements are each constrained to extend beyond the first joint 506 so as to reach the second joint and the third joint, respectively. Therefore, the first drive element in the second pair of drive elements B1 passes through one side of the first pulley 705 of the first group of pulleys on the first joint axis 510, and the second drive element in the second pair of drive elements B2 passes through the opposite side of the second pulley 706 of the first group of pulleys on the first joint axis 510, so that no matter how the support body 509 rotates around the first joint 506, the lengths of the second pair of drive elements B1 and B2 remain the same. Similarly, the first drive element in the third pair of drive elements C1 passes through one side of the second pulley 706 of the first group of pulleys on the first joint axis 510, and the second drive element in the third pair of drive elements C2 passes through the opposite side of the first pulley 705 of the first group of pulleys on the first joint axis 510, so that no matter how the support body 509 rotates around the first joint 506, the lengths of the third pair of drive elements C1 and C2 remain the same. If the arrangement of the instrument interface is symmetrical for both the second pair of drive elements B1, B2 and the third pair of drive elements C1, C2, the length of the second pair of drive elements is the same as the length of the third pair of drive elements for all rotation angles of the support 509 around the first joint 506. In each configuration of the surgical instrument, the second and third pairs of drive elements remain taut. They never relax. Therefore, there is no rebound when any joint of the surgical instrument is articulated. Therefore, in each configuration of the surgical instrument, full control of all three degrees of freedom of movement of the surgical instrument is achieved.

[0051] Suitably, each pulley in the first set of pulleys 601 comprises a pair of pulley elements. The first pulley 705 comprises an inner pulley element 708 and an outer pulley element 709. The inner pulley element 708 is located between the outer pulley element 709 and the first pair of drive elements A1, A2. Suitably, the inner pulley element 708 abuts against the outer pulley element 709. The inner pulley element 708 can be fixed by the outer pulley element 709. The inner pulley element 708 can be formed integrally with the outer pulley element 709. The second pulley 706 comprises an inner pulley element 710 and an outer pulley element 711. The inner pulley element 710 is located between the outer pulley element 711 and the first pair of drive elements A1, A2. Suitably, the inner pulley element 710 abuts against the outer pulley element 711. The inner pulley element 710 can be fixed by the outer pulley element 711. The inner pulley element 710 may be formed integrally with the outer pulley element 711. Each pulley element includes a groove for seating a drive element.

[0052] Suitably, each pulley of the second set of pulleys 602 comprises a pair of pulley elements. The first pulley 701 comprises an inner pulley element 712 and an outer pulley element 713. The inner pulley element 712 is located between the outer pulley element 713 and the first pair of drive elements A1, A2. Suitably, the inner pulley element 712 abuts against the outer pulley element 713. The inner pulley element 712 can be fixed by the outer pulley element 713. The inner pulley element 712 can be formed integrally with the outer pulley element 713. The second pulley 702 comprises an inner pulley element 714 and an outer pulley element 715. The inner pulley element 714 is located between the outer pulley element 715 and the first pair of drive elements A1, A2. Suitably, the inner pulley element 714 abuts against the outer pulley element 715. The inner pulley element 714 can be fixed by the outer pulley element 715. The inner pulley element 714 may be integrally formed with the outer pulley element 715. Each pulley element includes a groove for seating a drive element.

[0053] The second pair of drive elements B1, B2 is constrained to move around the inner pulley element 712 of the first pulley of the second set of pulleys and the outer pulley element 715 of the second pulley of the second set of pulleys. The second pair of drive elements B1, B2 is constrained to move around the inner pulley element 708 of the first pulley of the first set of pulleys and the outer pulley element 711 of the second pulley of the first set of pulleys.

[0054] The third pair of drive elements C1, C2 is constrained to move around the outer pulley element 713 of the first pulley of the second set of pulleys and the inner pulley element 714 of the second pulley of the second set of pulleys. The third pair of drive elements C1, C2 is constrained to move around the outer pulley element 709 of the first pulley of the first set of pulleys and the inner pulley element 710 of the second pulley of the first set of pulleys.

[0055] Thus, the second pair of drive elements B1, B2 have symmetrically opposed paths around the first set of pulleys 601 and the second set of pulleys 602, rather than the third pair of drive elements C1, C2. In a straight configuration of the instrument with the end effector aligned with the shaft, the paths of the second pair of drive elements B1, B2 around the pulley arrangement are rotationally symmetrical with the paths of the third pair of drive elements C1, C2 around the pulley arrangement about the longitudinal axis of the shaft 511. The second pair of drive elements B1, B2 and the third pair of drive elements C1, C2 emerge from the second set of pulleys 602 into the distal end of the shaft in a symmetrical arrangement. As can be seen from Figure 7It is easier to see that drive elements B1 and C2 appear adjacent to each other on one side of the shaft, while drive elements C1 and B2 appear adjacent to each other on the opposite side of the shaft. The arrangement of drive elements B1 and C2 in the shaft is rotationally symmetrical relative to the arrangement of drive elements C1 and B2 in the shaft with respect to the longitudinal axis of the shaft 511. The second set of pulleys 602 redirects the second and third pairs of drive elements from the first set of pulleys 601 into the shaft in this way.

[0056] Figure 7 The distal end of the surgical instrument in five different configurations is illustrated. Configuration (c) is the straight configuration mentioned above, in which the end effector is aligned with the instrument axis. In configurations (a), (b), (d) and (e), rotation around the first joint occurs relative to configuration (c). In configurations (a), (b), (d) and (e), no rotation around any of the second joint or the third joint occurs relative to configuration (c). Starting from configuration (c), the drive element A2 (not shown) is pulled to cause rotation around the first axis 510, thereby causing the arrangement of configuration (b). Further pulling the drive element A2 to cause further rotation around the first axis 510, thereby causing the arrangement of configuration (a). Starting from configuration (c), pulling the drive element A1 (not shown) to cause rotation around the first axis 510 in the opposite direction to configurations (a) and (b), thereby causing the arrangement of configuration (d). Further pulling the drive element A1 to cause further rotation around the first axis 510, thereby causing the arrangement of configuration (e).

[0057] The rotation of the end effector 501 about the first axis 510 is defined by the maximum travel of the first pair of drive elements A1, A2 about the first joint 506. Configuration (a) shows the end effector 501 at maximum rotation in one direction about the first axis 510, and configuration (e) shows the end effector 501 at maximum rotation in the opposite direction about the first axis 510. The maximum rotation angle relative to the longitudinal axis of the shaft 511 in both configurations is angle The second set of pulleys 602 are positioned relative to the first set of pulleys 601 so that even at the maximum rotation angle The second and third pairs of drive elements are also ensured to remain in contact with both the first set of pulleys 601 and the second set of pulleys 602. For all rotation angles of the end effector 501 about the first axis 510, the end effector 501 is always located within the cone defined by the tangent connecting the first pulley 701 of the second set of pulleys and the first pulley 705 of the first set of pulleys. This tangent is the path taken by the drive elements. When the second and third joints are held in Figure 5a and Figure 5b When in the straight configuration, the end effector 501 is located in the cone, such as Figure 7All configurations are shown in the table below. Figure 7 As can be seen, without the second set of pulleys 602, drive elements B2 and C1 will lose contact with the first set of pulleys 601 in configuration (a). Without the second set of pulleys 602, drive elements B1 and C2 will lose contact with the first set of pulleys 601 in configuration (e).

[0058] The second pair of drive elements and the third pair of drive elements remain in contact with the first set of pulleys and the second set of pulleys for all rotation angles of the end effector relative to the longitudinal axis of the shaft. Therefore, regardless of the rotation around the first joint 506, the length of the second pair of drive elements B1, B2 will remain the same. In addition, regardless of the rotation around the first joint 506, the length of the third pair of drive elements C1, C2 will remain the same. Therefore, regardless of how the first joint 506 is driven around the first axis 510, the second set of pulleys enables tension to be maintained in the second drive element and the third drive element. Therefore, control of the second drive element and the third drive element is maintained regardless of how the first joint 506 is driven around the first axis 510.

[0059] The pulley arrangement further comprises a pair of redirection pulleys 716, 717. These redirection pulleys are located in the articulation 505 between the first joint 506 and the second joint 507 and the third joint 513. The redirection pulleys are positioned to redirect the second pair of drive elements B1, B2 from the first set of pulleys 601 to the second joint 507 and to redirect the third pair of drive elements C1, C2 from the first set of pulleys 601 to the third joint 513.

[0060] The second pair of drive elements B1, B2 is constrained to move around the first redirection pulley 716. The first redirection pulley 716 rotates around the first redirection pulley axis 718. The first redirection pulley axis 718 is at an angle θ to the first axis 510. The angle θ causes the first drive element of the second pair of drive elements B1 to be redirected from the lead-out point of the first pulley 705 of the first set of pulleys 601 to the pick-up point 721 on the second joint 507. Suitably, the first redirection pulley 716 comprises a recess for seating the drive element B1. The third pair of drive elements C1, C2 is not constrained to move around the first redirection pulley 716. However, the second drive element of the third pair of drive elements C2 is passed between the lead-out point of the third joint 513 and the pick-up point on the first pulley 705 of the first set of pulleys 601 by the first redirection pulley 716. The drive element C2 may be partially surrounded by the first redirection pulley 716. For example, the drive element C2 may partially pass between the two wings of the groove of the first redirecting pulley 716 , but the drive element C2 is not disposed in the groove of the first redirecting pulley 716 .

[0061] The third pair of drive elements C1, C2 is constrained to move around the second redirection pulley 717. The second redirection pulley 717 rotates around the second redirection pulley axis 719. The second redirection pulley axis 719 makes an angle ψ with the first axis 510. The angle ψ redirects the first drive element of the third pair of drive elements C1 from the lead-out point 720 of the second pulley 706 of the first set of pulleys 601 to a pick-up point on the third joint 513. Suitably, the second redirection pulley 717 comprises a recess for seating the drive element C1. The second pair of drive elements B1, B2 is not constrained to move around the second redirection pulley 717. However, the second drive element of the second pair of drive elements B2 is passed between the lead-out point 720 of the second joint 507 and the pick-up point on the second pulley 706 of the first set of pulleys 601 by the second redirection pulley 717. The drive element B2 may be partially surrounded by the second redirection pulley 717. For example, the drive element B2 may partially pass between the two wings of the groove of the second redirecting pulley 717 , but the drive element B2 is not disposed in the groove of the second redirecting pulley 717 .

[0062] The lead-out point is the point where the drive element loses contact with the pulley. The pick-up point is the point where the drive element first contacts the pulley. For a drive element passing directly from a first pulley to a second pulley, the lead-out point of the drive element from the first pulley and the pick-up point of the drive element on the second pulley are points on a tangent to both the first pulley and the second pulley, the lead-out point being where this tangent intersects the first pulley, and the pick-up point being where this tangent intersects the second pulley. This is for illustrative purposes only and is negligible depending on the thickness of the drive element. Thus, in practice, the thickness of the tangent is equal to the thickness of the drive element, the lead-out point being where one side of the tangent meets the first pulley, and the pick-up point being where the other side of the tangent meets the second pulley.

[0063] The redirection pulley 716 causes the drive element B1 to wrap more completely around the second joint 507 than would occur if the redirection pulley 716 were not there, thereby increasing the engagement length between the drive element B1 and the second joint 507. As a result, the drive element B1 has a greater stroke around the second joint 507 and can therefore cause the end effector element 502 to rotate about the second axis 512 more than would occur without the redirection pulley 716. The redirection pulley 716 causes the pick-up point of the drive element B1 on the second joint 507 to change relative to the situation without the redirection pulley 716.

[0064] The redirection pulley 717 causes the drive element C1 to wrap more completely around the third joint 513 than would occur if the redirection pulley 717 were not there, thereby increasing the engagement length between the drive element C1 and the third joint 513. As a result, the drive element C1 has a greater stroke around the third joint 513 and can therefore cause the end effector element 503 to rotate about the second axis 512 more than would occur without the redirection pulley 717. The redirection pulley 717 causes the pick-up point of the drive element C1 on the third joint 513 to change relative to the situation without the redirection pulley 717.

[0065] The redirecting pulleys are each positioned on opposite sides of the hinge towards the outer edge of the hinge. Figure 5a It is easier to see. Figure 6a As can be seen in , each redirection pulley is located between the longitudinal axis of the hinge and the outer contour of the hinge, on opposite sides of the hinge. Suitably, the diameter of each redirection pulley maximizes the available space. In other words, the redirection pulley is as large as possible while enabling one drive element to engage the pulley on one side of the pulley and another drive element to approach the pulley unhindered on the opposite side of the pulley, the pulley and the two drive elements being enclosed within the contour of the hinge.

[0066] The first redirection pulley 716 lies in a plane defined by: (i) the desired take-off point of the drive element B1 from the first pulley 705 of the first set of pulleys 601; (ii) the desired pick-up point of the drive element B1 on the second joint 507; and (iii) a point on the boundary of the hinge that allows the first redirection pulley 716 to be enclosed within the boundary of the hinge when lying in the plane. Suitably, the first redirection pulley 716 is as large as possible while still lying in the plane, being enclosed within the contour of the hinge, not obstructing the path of the drive element C2, and allowing the drive element B1 to move freely around it.

[0067] The second redirection pulley 717 lies in a plane defined by: (i) the desired take-off point of the drive element C1 from the second pulley 706 of the first set of pulleys 601; (ii) the desired pick-up point of the drive element C1 on the third joint 513; and (iii) a point on the boundary of the hinge that enables the second redirection pulley 717 to be enclosed within the boundary of the hinge when located in the plane. Suitably, the second redirection pulley 717 is as large as possible while still lying in the plane, being enclosed within the contour of the hinge, not obstructing the path of the drive element B2, and enabling the drive element C1 to move freely around it.

[0068] The desired lead-out point and the desired pick-up point are determined to allow a desired travel of the drive element about the second joint and the third joint to allow a desired maximum rotation of the end effector element about the second axis.

[0069] The first redirection pulley and the second redirection pulley are located in different planes. Figure 6a As can be seen in FIG. 5 , these planes may be symmetric about a plane perpendicular to the first axis 510. These planes may be rotationally symmetric about a plane perpendicular to the first axis 510. Specifically, these planes may be rotationally symmetric about a line in a plane perpendicular to the first axis 510. When the instrument is in Figure 6a 511. When in the straight configuration illustrated in FIG. 51 , these planes are rotationally symmetric about the longitudinal axis of shaft 511. This is second-order rotational symmetry. These planes can be a reflection of each other in a plane perpendicular to the first axis 510. In the illustrated example, the end effector elements 502 and 503 are rotationally symmetric, and the path of the drive element around the joints 507 and 513 is rotationally symmetric. Alternatively, the axes of the end effector elements 502 and 503 can be rotationally asymmetric, and / or the path of the drive element around the joints 507 and 513 can be asymmetric. The path of the drive element around the joints 507 and 513 can be asymmetric due to the joints having different diameters (to achieve different tensioning ratios) and / or being positioned at different places away from the centerline of the support body 509. In any of these alternative examples, the first redirection pulley 716 and the second redirection pulley 717 will not be rotationally symmetric. The first redirection pulley 716 and the second redirection pulley 717 will have different sizes and / or different positions in order to cause the drive element to have a desired take-off point and a desired pick-up point as previously described.

[0070] Suitably, the entire pulley arrangement including the first set of pulleys, the second set of pulleys and the redirecting pulley is symmetrical about a plane perpendicular to the first axis 510. In particular, a first partial arrangement including the first pulley of the first set of pulleys 705, the first pulley of the second set of pulleys 701 and the first redirecting pulley 716 is rotationally symmetrical with a second partial arrangement including the second pulley of the first set of pulleys 706, the second pulley of the second set of pulleys 702 and the second redirecting pulley 717 about a plane perpendicular to the first axis 510. Suitably, the first partial arrangement is a reflection of the second partial arrangement in the mentioned plane perpendicular to the first axis 510. The second pair of drive elements B1, B2 is constrained to move around the pulley arrangement in a rotationally symmetrically opposite manner to the third pair of drive elements C1, C2 being constrained to move around the pulley arrangement. Because the pulley arrangement has the described symmetry, the second drive element and the third drive element constrained to move symmetrically around the pulley arrangement also have the same symmetry. Therefore, the path of the second pair of drive elements B1 , B2 around the pulley arrangement is rotationally symmetrical to the path of the third pair of drive elements C1 , C2 around the pulley arrangement.

[0071] In the exemplary embodiment, the first redirection pulley and the second redirection pulley are mounted on a support body 509 . Fig.10 The support body 509 and the redirection pulleys are shown separately. Each redirection pulley is mounted to the surface of the support body 509 by a spindle. Spindle 1001 fixes the first redirection pulley 716 to the support body 509. Spindle 1102 also fixes the second redirection pulley 717 to the support body 509.

[0072] like Fig.11 As more clearly shown in the view shown, the support body 509 has an inclined surface 1101 to which the first redirection pulley 716 is mounted. The first redirection pulley 716 has a mounting surface 1104 facing the inclined surface 1101 of the support body 509. The mounting surface 1104 is flush with the inclined surface 1101.

[0073] The first redirection pulley has an opposing surface 1105 that is opposite to the mounting surface 1104. The opposing surface 1105 is parallel to the mounting surface 1104. The support body 509 has another inclined surface, and the second redirection pulley 717 is mounted on the other inclined surface through the main shaft 1103. The second redirection pulley 717 has a mounting surface 1106, and the mounting surface 1106 faces the inclined surface 1102 of the support body 509. The mounting surface 1106 is flush with the inclined surface 1102. The second redirection pulley has an opposing surface 1107 that is opposite to the mounting surface 1102. The opposing surface 1107 is parallel to the mounting surface 1102.

[0074] The inclined surface 1101 of the support body 509 is not parallel to the longitudinal axis of the support body. The inclined surface 1101 of the support body 509 lies in a plane 1108, which is parallel to the plane 1109 in which the first redirecting pulley 716 lies. In other words, the inclined surface 1101 lies in a plane 1108 parallel to the plane 1109, and the plane 1109 is defined by the following three points: (i) the desired lead-out point of the drive element B1 from the first pulley 705 of the first set of pulleys 601; (ii) the desired pick-up point of the drive element B1 on the second joint 507; and (iii) a point on the boundary of the hinge that causes the first redirecting pulley 716 to be enclosed within the boundary of the hinge when it is located in the plane 1109. The plane 1108 of the inclined surface 1101 is half the width of the first redirecting pulley 716 (at Fig.11 The deviation from the plane 1109 defined by these points is shown as d1).

[0075] The inclined surface 1102 of the support body 509 lies in a plane 1110 that is parallel to a plane 1111 in which the second redirecting pulley 717 lies. In other words, the inclined surface 1102 lies in a plane 1110 that is parallel to the plane 1111, and the plane 1111 is defined by the following three points: (i) the desired extraction point of the drive element C1 from the second pulley 706 of the first set of pulleys 601; (ii) the desired pickup point of the drive element C1 on the third joint 513; and (iii) a point on the boundary of the hinge that allows the second redirecting pulley 717 to be enclosed within the boundary of the hinge when it lies in the plane 1111. The plane 1110 of the inclined surface 1101 is half the width of the second redirecting pulley 717 (at Fig.11 The first redirection pulley 716 and the second redirection pulley 717 are of the same shape and size. In this case, d1 = d2.

[0076] As discussed above, each redirection pulley is mounted to a corresponding inclined surface of the support body by a spindle. The spindle includes a spindle body and a spindle head. The spindle body passes through the central aperture of the redirection pulley. The central aperture is a through hole extending vertically between the mounting surface and the opposing surface of the redirection pulley. The spindle body passes through the central aperture of the redirection pulley and enters the hole of the support body. Fig.12 and Fig.13 The support body 509 is illustrated separately. An exemplary embodiment of a hole in the support body is depicted in these figures. The hole is a recess in the support body that tapers to a point. The spindle body passes through the initial opening of the hole and is securely stored in the tapered section. The spindle head is larger than the central aperture of the redirection pulley and cannot pass through the central aperture of the redirection pulley. Therefore, the spindle head fixes the redirection pulley flush on the inclined surface of the support body. The spindle head contacts at least a portion of the opposing surface of the redirection pulley and, by this contact, holds the redirection pulley against the inclined surface.

[0077] Reference Fig.14, the diameter of the hole 1401 through the support body is greater than the diameter of the spindle body 1403. The diameter of the central aperture 1402 of the redirection pulley may be greater than the diameter of the spindle body 1403. Therefore, the spindle body may fit loosely through the central aperture of the redirection pulley. In the example above the tapered section, the spindle body fits loosely through the hole of the support body (except for the area where it is fixed to the hole). Typically, the hole through the support body is created during manufacturing by drilling through the bevel of the support body. Because the diameter of the opening of the hole in the bevel is greater than the spindle body, the accuracy of the angle at which the support body is drilled to create the hole is not important. The spindle is located in the hole at the correct angle to make the redirection pulley flush with the bevel. It will be important that the angle of the hole is drilled very accurately if the fit of the spindle body through the hole is a tight fit and as a means of causing the redirection pulley to rotate around the redirection pulley axis 718, 719. In this case, the pulley will fit tightly onto the spindle, and the spindle will fit tightly into the hole, preventing the pulley from traveling. Therefore, there will be no room for manufacturing deviations in the angle of the hole drilled through the support body. However, in the described embodiment, the redirection pulley is caused to rotate about the redirection pulley axis 718, 719 by holding the redirection pulley flush against the inclined surface of the support body 509 that is perpendicular to the redirection pulley axis 718, 719. Therefore, in the described implementation, a larger manufacturing accuracy variation in the angle of the hole drilled through the support body is acceptable.

[0078] The inclined surfaces 1101 and 1102 of the support body are not parallel to each other. The inclined surface may be symmetrical about a plane perpendicular to the first axis 510. The inclined surface may be rotationally symmetrical about a plane perpendicular to the first axis 510. Specifically, the inclined surface may be rotationally symmetrical about a line in a plane perpendicular to the first axis 510. When the instrument is in Figure 5a In the straight configuration shown in FIG. 5 , the inclined planes are rotationally symmetric about the longitudinal axis of the shaft 511. This is second-order rotational symmetry. The inclined planes can be reflections of each other in a plane perpendicular to the first axis 510.

[0079] Reference Fig.15 In one example, the support body 509 includes a groove adjacent to each ramp for seating a drive element. The support body includes a groove 1501 adjacent to the ramp 1101 for seating a second drive element C2 of the third pair of drive elements. The drive element C2 is seated in the groove 1501 and is partially surrounded by the first redirecting pulley 716. The support body includes a groove 1502 adjacent to the ramp 1102 for seating a second drive element B2 of the second pair of drive elements. Fig.11 A groove 1502 is shown. The drive element B2 is positioned in the groove 1502 and is partially surrounded by the second redirecting pulley 717 .

[0080] The first pair of drive elements, the second pair of drive elements, and the third pair of drive elements extend through the instrument shaft from a distal end of the shaft connected to the hinge portion to a proximal end of the shaft connected to a drive mechanism of the instrument interface. Fig.17a and Fig.17b Two views of a first pair of drive elements, a second pair of drive elements, and a third pair of drive elements extending from the depicted articulation to an exemplary instrument interface 1701 are illustrated. In the exemplary embodiment, the second pair of drive elements and the third pair of drive elements overlap in the shaft, emerging from the proximal end of the shaft in a different arrangement than they would be in the distal end of the shaft. Fig.16a and Fig.16b A cross section of the shaft is shown, depicting the location of the drive elements.

[0081] Fig.16a A cross section of the shaft at the distal end of the shaft is shown. In other words, Fig.16a The position of the drive elements just after leaving the second set of pulleys 602 is shown. Drive elements A1 and A2 are located at opposite sides of the shaft after leaving the first joint 506. Drive elements C1 and B2 are also adjacent to each other on the side of the shaft opposite to drive elements B1 and C2 (adjacent to each other). Drive elements C1 and B2 are offset from drive elements B1 and C2 with respect to an axis 1601 which is transverse to axis 1602 connecting drive elements A1 and A2. This is a result of the offset axis of the two pulleys of the second set of pulleys.

[0082] Fig.16b A cross section of the shaft at the proximal end of the shaft is shown. In other words, Fig.16b The position of the drive element is shown when the shaft is about to exit and enter the instrument interface. The first pair of drive elements A1 and A2 are connected to Fig.16a A similar arrangement is located on opposite sides of the shaft. The first pair of drive elements can be brought closer together by virtue of the fact that the first pair of drive elements have been slightly moved toward each other as they pass through the shaft. Fig.16b In the example, the drive element B1 is located at the axis of Fig.16a On the side opposite to the position in Fig.16b In the example, the driving element C1 is located at the axis of Fig.16a For this purpose, the drive element B1 and the drive element C1 do not extend parallel to the longitudinal axis of the shaft 511 along the shaft. Instead, the drive element B1 and the drive element C1 overlap each other within the range of the shaft. This overlap occurs without the drive elements B1 and C1 colliding, because they are Fig.16a The offset position is caused by the pulleys of the second set of pulleys 602 having an offset axis. The drive element B2 moves slightly in the shaft, but remains in contact with the shaft. Fig.16a The drive element C2 moves slightly in the shaft but remains at the same side of the shaft as the drive element B1. Fig.16a on the same side of the shaft as in the embodiment of the present invention, so as to appear at the proximal end of the shaft adjacent to the drive element C1.

[0083] The instrument interface includes another pulley arrangement about which the first pair of drive elements, the second pair of drive elements, and the third pair of drive elements are constrained to move. The drive elements A1, A2, B1, B2, C1, and C2 are configured to enable them to directly engage with components of the instrument interface. In one embodiment, the drive elements are present at the proximal end of the shaft (e.g., Fig.16b The shaft is preferably provided with a plurality of first, second and third drive elements, each of which is actuated by a plurality of pulleys (shown in the drawings) for direct engagement with another pulley arrangement of an instrument interface described herein. Suitably, the first, second and third drive elements extend from the pulley arrangement at the distal end of the shaft to the instrument interface without winding around any intervening pulleys. Suitably, there are no intervening pulleys in the shaft around which the first, second and / or third pair of drive elements are constrained to move.

[0084] like Fig.17a and Fig.17b As can be seen in the figure, the device interface is relatively flat. Most of the device interface is Fig.17a Suitably, the instrument axis 504 is rigidly attached to the instrument interface 1701. The instrument axis 504 does not rotate or otherwise move relative to the instrument interface 1701. Suitably, the second axis 512 about which the end effector elements 502, 503 rotate is perpendicular to the central plane of the instrument interface. This is Fig.17a and Fig.17b The situation in the straight configuration of the instrument is shown. Thus, in the straight configuration of the instrument, the jaws of the end effector can move in the center plane of the instrument interface.

[0085] The drive element can be a uniform component of the same shape and size along its length and composed of the same material along its length. Alternatively, the drive element can be composed of different parts. In one example, the portion of the drive element that engages with the components of the instrument interface (such as pulleys and interface elements) is flexible. Similarly, the portion of the drive element that engages with the components of the distal end of the surgical instrument (such as pulleys and joints in the hinge) is flexible. Between these two flexible portions is Fig.17a and Fig.17b1702 as shown in the figure. Thus, each pair of drive elements includes two spokes and two flexible portions. Each pair of drive elements forms a loop. The loop includes alternating spokes and flexible portions. The two spokes are mainly or completely enclosed in the instrument shaft. One end of the distal flexible portion terminates in the distal end of one spoke, and the other end terminates in the distal end of the other spoke. The distal flexible portion engages a component of the hinge. One end of the proximal flexible portion terminates in the proximal end of one spoke, and the other end terminates in the proximal end of the other spoke. The proximal flexible portion engages a component of the instrument interface. The spokes are stiffer than the flexible portion. Suitably, the spokes are rigid. The spokes can be hollow. Typically, the diameter of the spokes is greater than the diameter of the flexible portion. Thus, the flexible portion can be a cable, and the spokes are hollow tubes. The flexible portion can terminate where it meets the spokes. Alternatively, the spokes can encapsulate the material of the flexible portion. For example, the spokes can be a rigid sheath covering a flexible cable.

[0086] The spokes are stiffer than the flexible portion. Thus, by forming a pair of drive elements from the spokes as well as the flexible portion, the likelihood of the drive elements stretching is reduced. For this reason, it is preferred to maximize the proportion of spokes in each drive element while ensuring that the spokes do not contact components of the hinge or instrument interface, and also ensuring that adjacent drive elements do not collide. The spokes are stronger than the flexible portion and are therefore more resilient than the flexible portion to compression and tension forces applied in any direction. Thus, by integrating the spokes, the drive element as a whole is stiff and less likely to stretch. Thus, the life of the drive element before needing to be re-tensioned or replaced is extended.

[0087] exist Fig.18 In FIG. 5 , the spokes of drive elements A1 , A2 , B1 , and C1 are visible, labeled A1s, A2s, B1s, and C1s, respectively. Fig.18 A straight configuration of the surgical instrument is depicted with end effector 501 aligned with axis 504. Fig.18 As can be seen in , the distal flexible portion of the drive element A1 terminates in the spoke A1s at a point 1801 along the longitudinal direction x of the shaft. The longitudinal direction x is the direction of the longitudinal axis 511 of the shaft. The distal flexible portion of the drive element A2 terminates in the spoke A2s at a point 1802 along the longitudinal direction x of the shaft. The distal flexible portion of the drive element B1 terminates in the spoke B1s at a point 1803 along the longitudinal direction x of the shaft. The distal flexible portion of the drive element C1 terminates in the spoke C1s at a point 1804 along the longitudinal direction x of the shaft. Fig.17a As can be seen in FIG. 1 , the distal flexible portions of drive elements B2 and C2 terminate in their respective spokes further toward the proximal end of the shaft.

[0088] like Fig.18, when the instrument is in the depicted straight configuration, the longitudinal positions 1801, 1802, 1803, and 1804 where the distal flexible portions of the drive elements terminate in the distal ends of the spokes do not coincide. Instead, the longitudinal positions 1801, 1802, 1803, and 1804 are offset from one another. In other words, when the instrument is in the straight configuration, the distal ends of the spokes of the drive elements are offset along the longitudinal direction of the shaft. Specifically, in the straight configuration, the distal ends of adjacent spokes are offset along the longitudinal direction of the shaft. In the straight configuration, the distal ends of spokes that are not adjacent to one another may coincide along the longitudinal direction of the shaft. For example, in Fig.18 , both non-adjacent spokes A1s and A2s terminate at the same point 1801, 1802 along the longitudinal direction of the shaft. Suitably, in each configuration of the surgical instrument, the distal ends of the spokes of the drive element are offset along the longitudinal direction of the shaft. Specifically, suitably, in each configuration of the surgical instrument, the distal ends of adjacent spokes are offset along the longitudinal direction of the shaft.

[0089] As previously mentioned Fig.16a and Fig.16b In the embodiments discussed, in which the drive elements pass directly from the pulley arrangement at the distal end of the shaft to the pulley arrangement in the instrument interface without moving around any intermediate pulleys, the drive elements do not all extend parallel to each other in the shaft. The first drive element A1 of the first pair of drive elements extends in the shaft substantially parallel to the second drive element A2 of the first pair of drive elements. The drive elements A1 and A2 can move slightly closer to each other within the length of the shaft in the direction from the hinge to the instrument interface. The first drive element B1 of the second pair of drive elements extends in the shaft at an angle to the second drive element B2 of the second pair of drive elements. The drive element B1 also extends along the shaft at an angle to the drive elements A1, A2, C1 and C2. The drive element B2 extends along the shaft at an angle to the drive elements A1, A2, C1 and C2. The first drive element C1 of the third pair of drive elements extends in the shaft at an angle to the second drive element C2 of the third pair of drive elements. The drive element C1 also extends along the shaft at an angle to the drive elements A1, A2, B1 and B2. Drive element C2 extends along the axis at an angle to drive elements A1 , A2 , B1 , and B2 .

[0090] The longitudinal position of the distal ends of the spokes is selected so that the spokes will not collide when the instrument is articulated. Because the diameter of the spokes is greater than the diameter of the flexible portion, while the flexible portion can extend along the length of the shaft without colliding, the spokes cannot. Suitably, the longitudinal position of the distal ends of the spokes in the straight configuration of the instrument is such that for any configuration of the end effector, no part of any drive element contacts part of another drive element. Suitably, the position of the proximal and distal ends of the spokes in the straight configuration is selected to maximize the length of the spokes while satisfying the condition that the drive elements will not contact. The spokes are stiffer than the flexible portion. Therefore, this maximizes the stiffness of the drive element while enabling the drive element to be wound around components in the hinge and the instrument interface. This maximizes the strength of the drive element while enabling the drive element to be wound around components in the hinge and the instrument interface.

[0091] exist Fig.19a In FIG. 5 , the spokes of drive elements A1 , A2 , B1 , and C1 are visible, labeled A1s, A2s, B1s, and C1s, respectively. Fig.19a A non-straight configuration of the surgical instrument is depicted, wherein the end effector 501 is not aligned with the axis 504. Fig.19a As can be seen in , the proximal flexible portion of drive element A1 terminates in spoke A1s at point 1901 along the longitudinal direction x of the shaft. The longitudinal direction x is the direction of the longitudinal axis 511 of the shaft. The proximal flexible portion of drive element A2 terminates in spoke A2s at point 1904 along the longitudinal direction x of the shaft. The proximal flexible portion of drive element B1 terminates in spoke B1s at point 1902 along the longitudinal direction x of the shaft. The proximal flexible portion of drive element C1 terminates in spoke C1s at point 1903 along the longitudinal direction x of the shaft. Fig.17a As can be seen in the , the proximal flexible portions of drive elements B2 and C2 terminate in their respective spokes further toward the distal end of the shaft. The spokes may terminate in the proximal flexible portion on the inner side of the shaft, as in the examples shown for drive elements B2 and C2. The spokes may terminate in the proximal flexible portion on the inner side of the instrument interface, as in the examples shown for drive elements A1, A2, B1, and C1. Some spokes may terminate in the proximal flexible portion on the inner side of the shaft, and some spokes may terminate in the proximal flexible portion on the inner side of the instrument interface. Fig.19a In the depicted design of the instrument interface, drive elements B2 and C2 engage pulleys as they enter the instrument interface from the shaft, so the spokes of drive elements B2 and C2 terminate in the shaft (not shown) in their proximal flexible portions to enable the proximal flexible portions to engage the pulleys. Drive elements A1, A2, B1, and C1 all extend some distance into the instrument interface before engaging with components of the instrument interface, so the spokes of drive elements A1, A2, B1, and C1 can extend into the instrument interface.

[0092] like Fig.19a As can be seen in the figure, the longitudinal positions 1901, 1902, 1903 and 1904 where the proximal flexible portion of the drive element terminates in the proximal ends of the spokes do not coincide. Instead, the longitudinal positions 1901, 1902, 1903 and 1904 are offset from one another. In other words, when the instrument is in the configuration shown, the proximal ends of the spokes of the drive element are offset in the longitudinal direction of the shaft. Suitably, for a straight configuration of the instrument, the proximal ends of the spokes of the drive element are offset in the longitudinal direction of the shaft. Specifically, in the straight configuration, the proximal ends of adjacent spokes are offset in the longitudinal direction of the shaft. In the straight configuration, the proximal ends of spokes that are not adjacent to one another may coincide in the longitudinal direction of the shaft. For example, in Fig.19a In the embodiment of the present invention, both non-adjacent spokes B1s and C1s terminate at the same point 1902, 1903 along the longitudinal direction of the shaft. Suitably, in each configuration of the surgical instrument, the proximal ends of the spokes of the drive element are offset along the longitudinal direction of the shaft. Specifically, suitably, in each configuration of the surgical instrument, the distal ends of adjacent spokes are offset along the longitudinal direction of the shaft.

[0093] The longitudinal position of the proximal ends of the spokes is selected so that the spokes do not collide when the instrument is articulated. Suitably, the longitudinal position of the proximal ends of the spokes in the straight configuration of the instrument is such that for any configuration of the end effector, no part of any drive element contacts part of another drive element.

[0094] Each pair of drive elements engages a single instrument interface element in the instrument interface. Each drive element engages an instrument interface element in the instrument interface. Fig.19a , Fig.19b and Fig.19c In the example illustrated in , each drive element engages its own instrument interface element. A single instrument interface element drives a pair of drive elements. Each drive element is independently driven by a single instrument interface. In alternative arrangements, there may be a compound drive motion in which more than one instrument interface element drives a single drive element, a single instrument interface element drives more than a pair of drive elements, or multiple instrument interface elements together drive multiple drive elements.

[0095] Fig.19b A first instrument interface element 1905 is illustrated engaging a first pair of drive elements A1, A2. A second instrument interface element 1906 engages a second pair of drive elements B1, B2. A third instrument interface element 1907 engages a third pair of drive elements C1, C2. Suitably, each drive element is secured to its associated instrument interface element. In other words, each drive element is secured with its associated instrument interface element.

[0096] The instrument interface 1701 has a significantly larger profile than the instrument shaft 504. Typically, the instrument shaft has a circular cross-section with a diameter less than or equal to 5 mm, while the corresponding cross-section through the instrument interface may be larger than the circular cross-section. The instrument interface includes an inner portion and an outer portion. The inner portion is composed of ( Fig.19a and Fig.19b The outer portion is defined by dashed line 1950 (shown in ). The outer portion is the remaining portion of the instrument interface that is not within the inner portion. The inner portion is within the projected contour of the shaft. In other words, the inner portion is the portion of the instrument interface that would be enclosed if the contour of the shaft continued within the instrument interface. The outer portion is outside the projected contour of the shaft. In the illustrated example, the shaft has a constant circular cross-section and is therefore divided into cylinders having the same circular cross-section as the shaft and having the same longitudinal axis 511 as the shaft. In other words, the inner portion is an extrapolation of the constant cross-section of the shaft in the instrument interface. Fig.19a from the side and in Fig.19b The inner portion 1950 is shown from the top.

[0097] The instrument interface elements 1905, 1906 and 1907 are dispersed across the width of the instrument interface, such as Fig.19b As shown. Fig.19b In the depicted arrangement, one instrument interface element 1905 is within the interior portion 1950 of the instrument interface. Specifically, the portion of the instrument interface element 1905 that engages the drive element is within the interior portion 1950 of the instrument interface. The entirety of the instrument interface element 1905 may be substantially within the interior portion 1950 of the instrument interface, such as Fig.19b As shown. The instrument interface element 1905 as a whole can be completely within the inner portion 1950 of the instrument interface. Suitably, the instrument interface element 1905 is aligned with the longitudinal axis 511 of the shaft 504. In the exemplary arrangement, only one instrument interface element is located within the inner portion of the instrument interface. The remaining instrument interface elements 1906, 1907 are within the outer portion of the instrument interface. These other instrument interface elements 1906, 1907 are located on either side of the aligned instrument interface element 1905. Specifically, the other instrument interface elements 1906, 1907 are located on both sides of the aligned instrument interface element 1905 in a direction perpendicular to the longitudinal axis of the shaft 511. The instrument interface elements 1906 and 1907 are not aligned with the longitudinal axis 511 of the shaft 504. The instrument interface elements 1906 and 1907 are constrained to move parallel to the longitudinal axis 511 of the shaft 504 because the instrument interface elements 1906 and 1907 are constrained to move along the tracks 1929 and 1930, respectively.

[0098] The instrument interface element 1905 engages the first pair of drive elements A1, A2. Fig.19a19, between the proximal end of the shaft and the instrument interface element 1905, the pair of drive elements A1, A2 are completely within the inner portion 1950. Between the proximal end of the shaft and the instrument interface element 1905, the pair of drive elements A1, A2 are completely parallel to the longitudinal axis of the shaft 511. Suitably, there are no intervening pulleys or other structures in the instrument interface that constrain the pair of drive elements A1, A2 to move thereabout between the proximal end of the shaft and the instrument interface element 1905. Suitably, only the instrument interface element 1905 engages its pair of drive elements A1, A2 in the inner portion 1950 of the instrument interface.

[0099] The instrument interface element 1906 engages the second pair of drive elements Bl, B2. The instrument interface element 1906 engages the second pair of drive elements Bl, B2 in an outer portion of the instrument interface.

[0100] The instrument interface element 1907 engages the third pair of drive elements C1 , C2. The instrument interface element 1907 engages the third pair of drive elements C1 , C2 in an outer portion of the instrument interface.

[0101] The pulley arrangement is used to transfer the drive elements to engage with the instrument interface elements in the outer portion. Each pair of drive elements engages the first pair of pulleys to transfer it from the proximal end of the shaft 504 to the corresponding instrument interface element, and engages the second pair of pulleys to move it from alignment with the instrument interface element back to alignment with the shaft 504.

[0102] In the arrangement shown, the second pair of drive elements B1, B2 emerges from the proximal end of the shaft in a direction aligned with the shaft. Fig.16a and Fig.16b 1904. The second pair of drive elements B1, B2 are then constrained to move about pulley pairs 1908 and 1909 to transition from where they emerge from the shaft 504 to engage the second instrument interface element 1906. The second pair of drive elements B1, B2 emerge from the pulley pairs 1908 and 1909 in a direction that is parallel to and offset from the direction in which the second pair of drive elements B1, B2 emerge from the proximal end of the shaft. The second pair of drive elements B1, B2 are constrained to move about pulley pairs 1910 and 1911 to transition from alignment with the second instrument interface element 1906 to alignment with the shaft 504.

[0103] In the arrangement shown, the third pair of drive elements C1, C2 emerges from the proximal end of the shaft in a direction aligned with the shaft. Fig.16a and Fig.16b504. The third pair of drive elements C1, C2 are then constrained to move about pulley pairs 1912 and 1913 to transition from where they emerge from the shaft 504 to engage the third instrument interface element 1907. The third pair of drive elements C1, C2 emerge from the pulley pairs 1912 and 1913 in a direction that is parallel to and offset from the direction in which the third pair of drive elements C1, C2 emerge from the proximal end of the shaft. The third pair of drive elements C1, C2 are constrained to move about pulley pairs 1914 and 1915 to transition from alignment with the third instrument interface element 1907 to alignment with the shaft 504.

[0104] exist Fig.19a , Fig.19b and Fig.19c In the arrangement shown, a pair of drive elements A1, A2 engages with a first instrument interface element 1905 within the inner portion. The pair of drive elements A1, A2 drives the articulated portion and thus drives the end effector about a first axis 510 (see Figure 5a ) rotation. The range of motion about first joint 506 is less than the range of motion about second joint 507 and third joint 513. As described below, first instrument interface element 1905 can be linearly displaced through a maximum distance d1 minus the length of first instrument interface element 1905, which is less than the maximum displacement d2 of second instrument interface element 1906 minus the length of second instrument interface element 1906, and less than the maximum displacement d3 of third instrument interface element 1907 minus the length of third instrument interface element 1907. Because motion about first joint 506 is controlled via a shorter range of instrument interface element travel than the second and third joints, greater sensitivity of this motion is preferred. The cable may slide and / or be pulled through the pulley. Therefore, it is preferred to utilize the simplest wiring scheme to transmit motion between the first instrument interface element and first joint 506.

[0105] By positioning first instrument interface element 1905 within the inner portion on the longitudinal axis of shaft 511 , the first pair of drive elements are not constrained to transmit about any intervening pulleys between first joint 506 and first instrument interface element 1905 .

[0106] Each instrument interface element is displaceable within the instrument interface. Because each instrument interface element is fixed to a corresponding pair of drive elements, displacement of the instrument interface element is transmitted to displacement of the pair of drive elements. Suitably, each instrument interface element is displaceable along the same line as the fixed line of the pair of drive elements. Each instrument interface element engages with a corresponding drive assembly interface element of the robot arm. Therefore, displacement of the instrument interface element is driven by the robot arm. In this way, the robot arm drives the paired drive elements.

[0107] Each pair of drive elements engages with an instrument interface element in the instrument interface. This pair of drive elements also engages with a tensioning mechanism and an alignment mechanism. When the instrument is manufactured, the tensioning mechanism is used to achieve the desired tension of a pair of drive elements. When the end effector has a predetermined configuration, the alignment mechanism is used to set the instrument interface element to a predetermined alignment position in the longitudinal direction of the shaft. Each instrument interface element has a displacement range within which it can be displaced. The predetermined alignment position can be the midpoint of the displacement range of each instrument interface element. The predetermined configuration of the end effector can be a straight configuration, in which the end effector elements are closed together (e.g., the jaws are closed), and the longitudinal axis of the hinge and the longitudinal axis of the end effector are aligned with the longitudinal axis of the shaft 511. When the end effector has a predetermined configuration, by setting the instrument interface element to a predetermined alignment position, when the instrument is replaced during surgery, the time taken to prepare for use of a new instrument can be reduced. In fact, when the instrument is removed from the robot arm, the robot arm assembly can be configured to enter an arrangement ready to receive the instrument interface element in a predetermined alignment position. For example, the robot arm assembly interface element may be brought into a default position in which the robot arm assembly interface element is arranged to receive each instrument interface element at the midpoint of its displacement range. The instrument is then manually placed into a predetermined configuration and then inserted into the robot arm. For example, a technician moves the articulated portion and the end effector into a straight configuration and then inserts the instrument into the robot arm. Because it is known that the instrument interface element has a predetermined alignment position when the instrument is in the predetermined configuration, the instrument interface element engages directly with the robot arm assembly interface element. Because the end effector is known to be in the predetermined configuration, the control system does not need to perform additional calibration or software setup procedures in order to map the position and orientation of the end effector.

[0108] The following describes a tensioning mechanism and an alignment mechanism that are independent of each other. By isolating the tensioning mechanism from the alignment mechanism, the process of achieving the desired tension and the desired alignment is simplified. Therefore, the time taken to achieve the desired tension and the desired alignment during manufacturing is reduced.

[0109] Fig.19a , Fig.19b and Fig.19c A tensioning mechanism utilizing pulleys is illustrated. Each pair of drive elements is tensioned independently. Each pair of drive elements is constrained to move around a displaceable pulley. Fig.19a , Fig.19b and Fig.19c Depicted are two different exemplary pulley arrangements for tensioning a pair of drive elements. In both examples, the pulleys can be displaced linearly.

[0110] Reference is first made to the tensioning mechanism shown for the pair of drive elements B1, B2 and C1, C2. First take a pair of drive elements B1, B2, the pulley 1911 is used to tension the pair of drive elements B1, B2. The pulley 1911 can be linearly displaced along a displacement axis 1920, which is parallel to the longitudinal axis 511 of the shaft. The displacement axis 1920 is offset from the longitudinal axis 511 of the shaft. Fig.19b A displacement axis 1920 is shown. The tension pulley 1911 is mounted to a block 1918, which can slide along a track 1919. Sliding the block 1918 along the track 1919 causes the pulley 1911 to be displaced along the displacement axis 1920. When the block 1918 moves away from the shaft, the tension of the second pair of drive elements B1, B2 increases. When the block 1918 moves toward the shaft, the tension of the second pair of drive elements B1, B2 decreases. Any suitable mechanism can be used to move the block. For example, a screw adjustment mechanism can be used. Fig.19a , Fig.19b and Fig.19c The screw adjustment mechanism in which screw 1921 is screwed into block 1918 is shown. Fig.19a 19. Screw 1921 is constrained by portion 1922 of the instrument interface such that screw 1921 can rotate but cannot be linearly displaced. Thus, as the screw rotates, the screw threads engage threads on the inside of block 1918, causing the block and, therefore, pulley 1911 to be linearly displaced. When screw 1921 is tightened, pulley 1911 moves in one linear direction. When screw 1921 is loosened, pulley 1911 moves in the opposite linear direction. Fig.19a , Fig.19b and Fig.19c The tensioning mechanism of the drive elements C1 , C2 depicted in FIG. 8 operates in a manner corresponding to that described with respect to the drive elements B1 , B2 .

[0111] Now refer to Fig.19a1 and 2. The tensioning mechanism shown for the first pair of drive elements A1, A2 in FIG. Pulley 1923 is used to tension the first pair of drive elements A1, A2. Pulley 1923 can be linearly displaced along a displacement axis 1924. Displacement axis 1924 is at a certain angle to the longitudinal axis 511 of the shaft. Suitably, displacement axis 1924 can be at a 45° angle to the longitudinal axis 511 of the shaft. Tensioning pulley 1923 is mounted to a block 1925 captured in a socket 1926 of the instrument interface. Block 1925 and tensioning pulley 1923 can slide through socket 1926. Sliding block 1925 through socket 1926 causes the pulley to shift along displacement axis 1924. When block 1925 slides further into the socket, the tension of the first pair of drive elements A1, A2 increases. When block 1925 slides out of the socket, the tension of the first pair of drive elements A1, A2 decreases. Any suitable mechanism may be used to move block 1925. For example, a screw adjustment mechanism as described above with respect to block 1918 may be used. Because the first pair of drive elements A1, A2 are wound almost completely around the tensioning pulley 1923 so that they extend nearly parallel to each other, more tension is applied per unit displacement of the tensioning pulley compared to the tensioning mechanisms described with respect to the second and third pairs of drive elements.

[0112] Although Fig.19a , Fig.19b and Fig.19c A first pair of drive elements are shown using an angled tensioning mechanism and a second and third pair of drive elements are shown using a linear tensioning mechanism, but any pair of drive elements may be tensioned using any suitable mechanism so long as the mechanism fits into the instrument interface.

[0113] Fig.20a An alternative tensioning mechanism is shown. Each pair of drive elements terminates in lugs 1927 of the instrument interface element (see Fig.19c ). Fig.20a Pictured Fig.19c An alternative arrangement of lugs 1927 is shown. Fig.20a In the arrangement, the lugs are used in the tensioning mechanism. Fig.20aThe lug has a pair of lug elements 2001 and 2002. One of the pair of drive elements terminates in one lug element, while the other of the pair of drive elements terminates in the other lug element. The first drive element C1 of the third pair of drive elements is depicted as terminating in the lug element 2001, and the second drive element C2 of the third pair of drive elements is depicted as terminating in the lug element 2002. A pair of lug elements are connected to be linearly displaceable relative to each other. Suitably, a pair of lug elements can be linearly displaced along the direction y of the pair of drive elements attached thereto. Suitably, a pair of lug elements can be displaced along a displacement axis that is parallel to and deviates from the longitudinal axis 511 of the shaft. The lug elements 2001 and 2002 can be connected by any suitable mechanism that can move the lug elements relative to each other along the displacement axis. For example, the lug elements can be connected together by screws 2003. The screw 2003 is captured in the first lug element 2002 and constrained by the first lug element 2002 to prevent the screw 2003 from being linearly displaced with respect to the first lug element 2002. For example, Fig.20a As shown, the screw can pass through a hole in the first lug element through which the screw can rotate, and is constrained by two parts 2004 and 2005 having a larger diameter than the hole through the first lug element to prevent linear displacement through the first lug element. The screw 2003 is screwed through the second lug element 2001. Therefore, the lug elements 2001 and 2002 are linearly displaced toward each other when the screw is tightened, and are linearly displaced away from each other when the screw is loosened.

[0114] Fig.20b Another alternative tensioning mechanism is illustrated. Fig.20b Pictured Fig.19c Another alternative arrangement of lugs 1927 is shown in FIG. Fig.20b In the arrangement, the lugs are used in the tensioning mechanism. Fig.20bThe lug has a pair of lug elements 2006 and 2007. One of the pair of drive elements terminates in one lug element, while the other of the pair of drive elements terminates in the other lug element. The first drive element C1 of the third pair of drive elements is depicted as terminating in the lug element 2006, and the second drive element C2 of the third pair of drive elements is depicted as terminating in the lug element 2007. A pair of lug elements are connected to be linearly displaceable relative to each other. Suitably, a pair of lug elements can be linearly displaced along the direction y of the pair of drive elements attached thereto. Suitably, a pair of lug elements can be displaced along a displacement axis that is parallel to and offset from the longitudinal axis 511 of the shaft. The lug elements 2006 and 2007 can be connected by any suitable mechanism that can move the lug elements relative to each other along the displacement axis. For example, the lug elements can be connected together by screws 2008. The screw 2008 is captured in the first lug element 2007 and constrained by the first lug element 2007 to prevent the screw 2008 from being linearly displaced relative to the first lug element 2007. Fig.20b As shown, the screw can pass through a hole in the first lug element that enables the screw to rotate, and is constrained by two parts 2009 and 2010 that have a larger diameter than the hole through the first lug element to prevent linear displacement through the first lug element. Screw 2008 is screwed through the second lug element 2006. Therefore, lug elements 2006 and 2007 are linearly displaced toward each other when the screw is tightened, and are linearly displaced away from each other when the screw is loosened.

[0115] Reference Fig.19c , each instrument interface element 1905, 1906 and 1907 can be linearly displaced parallel to the longitudinal axis of shaft 511. The instrument interface elements can slide along a linear track. For example, the first instrument interface element 1905 can slide along track 1928, the second instrument interface element 1906 can slide along track 1929, and the third instrument interface element 1907 can slide along track 1930. Each instrument interface element can be displaced within a displacement range between a minimum displacement position and a maximum displacement position. For example, the minimum displacement position and the maximum displacement position can be determined by the two ends of the track along which the instrument interface element slides in the longitudinal direction x of the shaft. The minimum displacement position and the maximum displacement position of the second instrument interface element 1906 and the third instrument interface element 1907 are within a range of displacements between the minimum displacement position and the maximum displacement position. Fig.19b and Fig.19c The minimum displacement position and the maximum displacement position of the first instrument interface element 1905 are marked as 1931 and 1932. Fig.19bare labeled 1931 and 1943 therein. The first instrument interface element can be linearly displaced in the direction x by a maximum distance d1 minus the length of the first instrument interface element. The second instrument interface element can be linearly displaced in the direction x by a maximum distance d2 minus the length of the second instrument interface element. The third instrument interface element can be linearly displaced in the direction x by a maximum distance d3 minus the length of the third instrument interface element. Suitably, d1 < d2 and d1 < d3. Suitably, d2 = d3.

[0116] Suitably, in the straight configuration of the instrument where the end effector is aligned with the shaft, the first instrument interface element 1905, the second instrument interface element 1906, and the third instrument interface element 1907 are all located in the same plane perpendicular to the longitudinal axis of the shaft. Alternatively, in the straight configuration of the instrument, the plane in which the first instrument interface element 1905 is centered may be different from the plane in which the second instrument interface element 1906 and the third instrument interface element 1907 are centered. This is because the midpoint of the travel of the first instrument interface element 1905 on d1 is offset from the midpoints of the travel of the second instrument interface element 1906 and the third instrument interface element 1907 on d2, d3.

[0117] Suitably, each instrument interface element includes bodies 1933, 1934, 1935 and lugs 1927, 1936, 1937. The bodies 1933, 1934, 1935 can be linearly displaced between the minimum displacement position and the maximum displacement position of the instrument interface element. A pair of drive elements that engage the instrument interface element are fixed to the lugs of the instrument interface element. The lugs can be linearly displaced within the bodies parallel to the direction along which the bodies are displaced. Suitably, the lugs can be linearly displaced along the longitudinal direction x of the shaft (parallel to the longitudinal axis 511 of the shaft). The alignment mechanism adjusts the displacement position of the body without displacing the lugs. For example, the alignment mechanism may include a screw adjustment mechanism coupled to the body and the lugs, which can move the body without moving the lugs. Fig.19c Such a screw adjustment mechanism is depicted. The bodies 1933, 1935 include slots 1938, 1939 that are aligned with the direction along which the bodies are displaced. Screws 1940, 1941 are screwed into the lugs via the slots 1938, 1939. The screws 1940, 1941 are constrained to slide along the slots. For example, the screw heads may be too large to pass through the slots, and the screw bodies fit loosely through the slots. Thus, when the screws are loose, the bodies can be displaced relative to the lugs along the width of the slots. When the screws are tightened, the bodies remain fixed using the lugs. Thus, the relative position of the bodies and the lugs can be adjusted by the width of the slots.

[0118] The steps to be performed during manufacturing after the instrument is assembled are described below in order to set the tension of the drive elements and the alignment of the instrument interface elements.

[0119] Initially, the instrument interface is released from the drive elements. The instrument interface elements are set to alignment positions. For example, if the alignment positions are the midpoints of travel of each instrument interface element over its displacement range, the instrument interface elements are aligned to these positions. This initial step may be a rough alignment of the instrument interface elements with their alignment positions. Alternatively, this initial step may not be performed. Next, the end effector is placed in a predetermined configuration. Next, the paired drive elements are tensioned. This can be accomplished using any of the tensioning mechanisms described herein, such as by sliding a tensioning pulley along a track or through a socket or by displacing a pair of lug elements. Once tensioned, the alignment mechanism is used to set the displacement positions of the instrument interface elements to predetermined alignment positions. For example, in Fig.19a , Fig.19b and Fig.19c In the illustrated embodiment, screws 1940, 1941 are loosened and the body 1933, 1935 of the instrument interface element is displaced along tracks 1930, 1929 relative to lugs 1938, 1937 until the body of the instrument interface element is in a predetermined alignment position. The end effector may be maintained in a predetermined configuration while the pair of drive elements are tensioned. Alternatively or additionally, the end effector may be returned to a predetermined configuration after the pair of drive elements have been tensioned. Then, the screws are tightened.

[0120] Fig.21a , Figure 21b and Fig.21c The drive assembly interface 2100 is illustrated. The drive assembly interface is located at the terminal end of the terminal link of the robot arm. This terminal link is connected to the link adjacent to it by a rolling joint. The rolling joint allows the terminal link to rotate around the longitudinal axis 2104 of the terminal link. The drive assembly interface 2100 includes drive assembly interface elements 2101, 2102 and 2103. The drive assembly interface elements are configured to receive instrument interface elements 1905, 1906 and 1907. The first drive assembly interface element 2102 is configured to receive the first instrument interface element 1905. The second drive assembly interface element 2101 is configured to receive the second instrument interface element 1906. The third drive assembly interface element 2102 is configured to receive the third instrument interface element 1907.

[0121] Each drive assembly interface element can be displaced in a direction parallel to the longitudinal axis 2104 of the drive assembly. Each drive assembly interface element can be displaced within a displacement range. When the instrument interface is placed in the drive assembly, such as Fig.24 As shown, each drive assembly interface element is displaceable in the same direction as the direction of displacement of the engaged instrument interface element.

[0122] The first drive assembly interface element 2102 engages the first instrument interface element 1905 at the longitudinal axis 2104 of the drive assembly. Thus, the first drive assembly interface element 1905 drives the first instrument interface element 1905 along the longitudinal axis of the drive assembly and hence along the longitudinal axis of the terminal link of the robotic arm. Suitably, among all drive assembly interface elements in the drive assembly, only the first drive assembly interface element 2102 is displaceable along the longitudinal axis 2104 of the terminal link. The first instrument interface element 1905 drives the first pair of drive elements A1, A2 to drive rotation of the distal end of the instrument about a first axis 510 perpendicular to the instrument shaft axis 511. When the instrument interface 1701 is disposed in the drive assembly 2100, the longitudinal axis 511 of the instrument shaft is parallel to the longitudinal axis 2104 of the terminal link. Suitably, the longitudinal axis 511 of the instrument shaft coincides with the longitudinal axis 2104 of the terminal link.

[0123] The second drive assembly interface element 2101 engages the second instrument interface element 1906 on an axis parallel to but offset from the longitudinal axis 2104 of the drive assembly. The second drive assembly interface element 2101 is displaceable along the axis to drive the second instrument interface element 1906 along the axis. The second instrument interface element 1906 drives the second pair of drive elements B1, B2 to drive the rotation of the end effector element 502 around the second joint 507.

[0124] The third drive assembly interface element 2103 engages the third instrument interface element 1907 on an axis parallel to but offset from the longitudinal axis 2104 of the drive assembly. The third drive assembly interface element 2103 is displaceable along the axis to drive the third instrument interface element 1907 along the axis. The third instrument interface element 1907 drives the third pair of drive elements C1, C2 to drive the rotation of the end effector element 503 about the third joint 513.

[0125] Suitably, the drive assembly interface element releasably engages a corresponding instrument interface element.

[0126] Fig.21a , Figure 21b and Fig.21cIllustrated is an exemplary mechanism for driving a linear shift of the drive assembly interface element within the drive assembly. Each drive assembly interface element 2101, 2102, 2103 is driven by a respective threaded drive shaft 2105, 2106, 2107. Suitably, the first drive assembly interface element, the second drive assembly interface element, and the third drive assembly interface element are driven independently by the drive shafts. The guiding structure constrains each drive assembly interface element, thereby preventing the drive assembly interface element from rotating as the corresponding drive shaft rotates. For example, the guide rail constrains each drive assembly interface element, thereby preventing the drive assembly interface element from rotating as the corresponding drive shaft rotates. The guide rail constrains the drive assembly interface element such that the only movement allowed for the drive assembly interface element is to linearly move parallel to the guide rail. For example, the drive assembly interface element can slide along the guide rail. In the illustrated embodiment, both the first drive assembly interface element 2102 and the second drive assembly interface element 2101 are constrained by the same guide rail 2108. The third drive assembly interface element 2103 is constrained by a different guide rail 2109. In an alternative arrangement, both the first drive assembly interface element 2102 and the third drive assembly interface element 2103 are constrained by the same guide rail 2109. The second drive assembly interface element 2101 is constrained by the guide rail 2108. In yet another alternative arrangement, each drive assembly interface element is constrained by its own guide rail. In another example, the guiding structure is a guiding groove that constrains the movement of the drive assembly interface element such that the drive assembly interface element can only linearly move parallel to the guiding groove. Like the guide rail, the guiding groove is parallel to the longitudinal direction 2104 of the drive assembly interface. The first drive assembly interface element 2102 can linearly shift through a maximum distance s1. The second drive assembly interface element 2101 can linearly shift through a maximum distance s2. The third drive assembly interface element 2103 can linearly shift through a maximum distance s3. Suitably, s1 < s2 and s1 < s3. Suitably, s2 = s3.

[0127] Suitably, in one configuration of the drive assembly, the first drive assembly interface element 2101, the second drive assembly interface element 2102, and the third drive assembly interface element are all located in the same plane perpendicular to the longitudinal axis 2104 of the terminal link. This configuration is Fig.21a 、 Figure 21b and Fig.21c. All drive assembly interface elements are centered on a single cross-section of the terminal link perpendicular to the longitudinal axis 2104. Suitably, in this configuration, each drive assembly interface element is located at the midpoint of a linear displacement within its displacement range. Suitably, this configuration is the default configuration adopted by the assembly interface when the instrument has been removed from the robot arm. The configuration is arranged to receive the instrument interface elements into the above-mentioned predetermined alignment position. The predetermined alignment position may be the position when each drive assembly interface element is at the midpoint of its stroke. The predetermined alignment position may be the position when the center points of all drive assembly interface elements are located on the same plane.

[0128] In all configurations of the drive assembly, both the second drive assembly interface element 2101 and the third drive assembly interface element 2103 are centered on a second plane that is perpendicular to the Fig.21a , Figure 21b and Fig.21c The depicted configurations are centered on a plane for the first drive assembly interface element 2102, the second drive assembly interface element 2102, and the third drive assembly interface element 2103. The second plane does not intersect the longitudinal axis 2104 of the terminal link. In all configurations, the first drive assembly interface element 2102 is centered on a third plane that is parallel to but offset from the second plane.

[0129] Fig.21a , Figure 21b and Fig.21c The drive assembly depicted in FIG. 1 can drive Fig.19a , Fig.19b and Fig.19c The device interface depicted in Fig.19a , Fig.19b and Fig.19c The device interface depicted in the figure also drives Figure 5a and Figure 5bThe first joint, second joint, and third joint depicted therein such that the first drive assembly interface element 2102 drives the first joint 506, the second drive assembly interface element 2101 drives the second joint 507, and the third drive assembly interface element 2103 drives the third joint 513. In an alternative arrangement, the drive assembly interface elements can drive different joints. For example, if the first pair of drive elements A1, A2 are connected to the second instrument interface element 1906, then the second drive assembly interface element 2101 drives the first joint 506. If the second pair of drive elements B1, B2 are connected to the first instrument interface element 1905, then the first drive assembly interface element 2102 drives the second joint 507. In this example, the third pair of drive elements C1, C2 are connected to the third instrument interface element 1907 such that the third drive assembly interface element 2103 drives the third joint 513. In this example, the first drive assembly interface element 2102 can linearly displace a maximum distance s1. The second drive assembly interface element 2101 can linearly displace through a maximum distance s2. The third drive assembly interface element 2103 can linearly displace a maximum distance s3. Suitably, s2 < s1 and s2 < s3. Suitably, s1 = s3.

[0130] Each instrument interface element includes a body that can be received in a corresponding socket of the drive assembly interface element. The body and the socket are shaped to correspond such that when the drive assembly interface element is displaced, the displacement is transferred to the instrument interface element without any slippage. Thus, the body fits snugly into the socket along at least one line in the displacement direction. Suitably, the instrument interface element can be displaced within the same displacement range as its corresponding drive assembly interface element.

[0131] Fig.22a An exemplary arrangement of the portion of the body of the instrument interface element that is received in the socket of the drive assembly interface element is illustrated. The body includes lower sidewalls 2201 and 2202 that are separated by the length of the body in the displaceable direction x. The lower sidewalls are perpendicular to the displaceable direction x of the body. Upper sidewalls 2203 and 2204 taper from the lower sidewalls to a point 2205. Suitably, the upper sidewalls taper symmetrically to a point. When the instrument interface engages the drive assembly interface, the point 2205 is first inserted into the drive assembly interface element, followed by the remainder of the upper sidewalls 2203, 2204, and finally the lower sidewalls 2201, 2202. The angle α at which the upper sidewalls converge is preferably less than or equal to 80°. By choosing α ≤ 80°, even if the body and the socket are not perfectly aligned along the displaceable direction x, as long as the point is inside the socket, the body will slide into the socket when a force is applied in the direction F. The direction F is perpendicular to the displaceable direction x. In other words, the direction F is perpendicular to the longitudinal axis of the shaft 504 and perpendicular to the longitudinal axis of the drive assembly.

[0132] Figure 22bAnother exemplary arrangement of the portion of the body of the instrument interface that is received in the receptacle of the drive assembly of the drive assembly interface element is shown. The body is similar to the reference except that the body has a roller 2206 located at the point where the two upper side walls meet. Fig.22a The body described is the same. The roller 2206 is configured to rotate about an axis perpendicular to the displaceable direction x. The angle β at which the upper side walls meet can be greater than 80°. This is because the roller 2206 assists in placing the body in the socket even if the body and the socket are not fully aligned along the displaceable direction x when a force is applied in the direction F.

[0133] Fig.22c Another exemplary arrangement of the portion of the body of the instrument interface that is received in the receptacle of the drive assembly of the drive assembly interface element is shown. The body is similar to the reference except that the body has rollers 2207, 2208 located on each upper side wall. Fig.22a The bodies described are identical. The rollers 2207, 2208 are configured to rotate about an axis perpendicular to the displaceable direction x. The angle γ at which the upper side walls meet can be greater than 80°. This is because the rollers 2207, 2208 help to seat the body in the socket even if the body and the socket are not perfectly aligned along the displaceable direction x when a force is applied in the direction F.

[0134] Fig.23 An exemplary arrangement of a socket of a drive assembly interface element is illustrated. The body includes side walls 2301 and 2302 separated by the length of the body in a displaceable direction x. The side walls are perpendicular to the displaceable direction x of the body. The side walls each terminate in a roller 2303, 2304. The rollers 2303, 2304 are configured to rotate around an axis perpendicular to the displaceable direction x. The rollers 2303, 2304 help to place the body in the socket even if the body and the socket are not fully aligned along the displaceable direction x when the instrument interface is applied to the drive assembly interface.

[0135] In one example, the length A of the body in the displaceable direction x is greater than the maximum distance that the body can travel in the displaceable direction x within the displacement range. Suitably, the length A of the body in the displaceable direction x is greater than the maximum distance that the socket of the drive assembly interface element can travel in the displaceable direction within its displacement range. Therefore, no matter what displacement position the body has and no matter what displacement position the socket has, when the instrument interface is engaged with the drive assembly interface, the body is placed in the socket. Therefore, there is no need for the instrument interface element and the drive assembly interface element to pre-align to cause the instrument interface and the drive assembly interface to match. Suitably, the maximum distance that the body can travel in its displacement range is half the length A / 2 of the body. A is the length of the body. Suitably, the maximum distance that the socket can travel in its displacement range is half the length A / 2 of the body.

[0136] In one example, the length B of the socket in the displaceable direction x is greater than the maximum distance that the main body can travel in the displaceable direction x within the displacement range. Suitably, the length B of the socket in the displaceable direction x is greater than the maximum distance that the socket of the drive assembly interface element can travel in the displaceable direction within its displacement range. Therefore, no matter what displacement position the main body has and no matter what displacement position the socket has, when the instrument interface is engaged with the drive assembly interface, the main body is placed in the socket. Therefore, there is no need for the instrument interface element and the drive assembly interface element to pre-align to cause the instrument interface and the drive assembly interface to match. Suitably, the maximum distance that the main body can travel in its displacement range is half the length B / 2 of the socket. B is the length of the socket. Suitably, the maximum distance that the socket can travel in its displacement range is half the length B / 2 of the socket.

[0137] Suitably, the length A of the body in the displaceable direction is equal to the length B of the socket in the displaceable direction.

[0138] The instrument interface may have a guide rod, which helps to align and place the instrument interface into the drive assembly interface when the instrument interface engages with the drive assembly interface. The guide rod is located on the outer surface of the instrument interface that faces the drive assembly interface when the instrument interface engages with the drive assembly interface. The guide rod is received in the drive assembly interface before the instrument interface element. Suitably, the guide rod is the first part of the instrument interface that is received in the drive assembly interface when the instrument interface and the drive assembly interface contact each other. Once the guide rod has been received in the drive assembly interface, it constrains the relative orientation that the instrument interface and the drive assembly interface can engage to adjust their longitudinal posture. Suitably, the guide rod only allows the instrument interface to be fully placed into the drive assembly interface when the longitudinal axis 511 of the instrument shaft is aligned with the longitudinal axis 2104 of the terminal link of the robot arm.

[0139] Suitably, the guide rod is elongated, straight and parallel to the longitudinal axis 511 of the instrument shaft. The guide rod may extend integrally across the instrument interface. For example, the guide rod may extend in the longitudinal direction x from the end of the instrument interface that abuts the instrument shaft 504 to the opposite end of the instrument interface. Alternatively, the guide rod may extend along the longitudinal direction x only within the longitudinal range defined by the minimum displacement position 1931 and the maximum displacement position 1932 of the instrument interface elements 1905, 1906, 1907. If the drive assembly interface and the instrument interface are arranged so that both adopt their default predetermined alignment positions before engagement, the guide rod may extend along the longitudinal direction x only within the longitudinal range defined by the displacement of the instrument interface elements when they are in the predetermined alignment position. If in the predetermined alignment position, the instrument interface elements are all aligned in the same plane perpendicular to the longitudinal axis 511 of the instrument shaft, the guide rod may extend along the longitudinal direction x only on the instrument interface element itself. Suitably, the guide rod is narrower than the diameter of the instrument shaft 504. The drive assembly receives a guide rod parallel to the longitudinal axis 2104 of the drive assembly.

[0140] The guide rod may be formed from a single part, such as Fig.19a 1960 is shown in FIG. The illustrated guide rod extends across the entire length of the instrument interface. The guide rod partially or entirely surrounds the drive elements A1, A2, B1, and C1. In this manner, the drive elements are not exposed to the exterior of the instrument interface when the instrument interface is engaged with the drive assembly interface. The guide rod 1960 also strengthens the instrument interface.

[0141] Alternatively, the guide rod may comprise more than two parts. Fig.25 A view of the surface of the instrument interface first engaged with the drive assembly interface is shown. Here, two guide rod portions 2501, 2502 are shown. The guide rod extends in the longitudinal direction x across the portion of the longitudinal range defined by the minimum displacement position and the maximum displacement position of the instrument interface element.

[0142] Both the guide rod and the first instrument interface element 1905 are received in the first drive assembly interface element 2102. The first instrument interface element includes two main body parts 1905a and 1905b, one main body part is located on one side of the guide rod, and the other main body part is located on the opposite side of the guide rod. The first drive assembly interface element includes two socket parts 2101a and 2101b on either side of the longitudinal axis 2104 of the drive assembly. When the instrument interface and the drive assembly interface are engaged, the guide rod is first received in the first drive assembly interface element. The guide rod is placed between the two socket parts 2101a and 2101b along the longitudinal axis 2104 of the shaft. Since the guide rod is received in the first drive assembly interface element 2101, the guide rod prevents the instrument interface from twisting when it is located in the drive assembly interface. When the drive assembly interface and the instrument interface are engaged, the guide rod causes the attitude of the drive assembly interface and the instrument interface to remain aligned. As the instrument interface is lowered further into the drive assembly interface, the first body portion 1905a engages the first socket portion 2101a on one side of the guide rod and the second body portion 1905b engages the second socket portion 2101b on the opposite side of the guide rod.

[0143] It will be appreciated that the drive assembly interface described herein can be modified to include other drive assembly interface elements for transmitting drive to other instrument interface elements. The instrument interface described herein can be modified to include other instrument interface elements for transmitting drive to other joints of the articulation at the distal end of the instrument shaft. The articulation itself can also be modified to include other joints.

[0144] It will also be appreciated that the end effector may have only one end effector element. In this case, the articulated portion does not include the third joint 513, the instrument interface does not include an instrument interface element for driving the third joint, and the drive assembly does not include a drive assembly interface element for driving this instrument interface element.

[0145] The device may be used for non-surgical purposes. For example, the device may be used in a cosmetic procedure.

[0146] Applicants hereby independently disclose each individual feature described herein and any combination of two or more such features, as long as these features or combinations can be implemented based on the entirety of this specification according to the common knowledge of those skilled in the art, regardless of whether these features or combinations of features solve any problem disclosed herein, and are not limited to the scope of the claims. Applicants point out that various aspects of the present invention may consist of any such individual features or combinations of features. In view of the foregoing description, it will be apparent to those skilled in the art that various modifications may be made within the scope of the present invention.

Claims

1. A robotic surgical instrument, comprising: a shaft extending between an instrument interface at one end and an articulation at another end; The articulated portion connects a first end effector element to the shaft, the articulated portion comprising: a first joint drivable by a first pair of drive elements, the first joint allowing the first end effector element to rotate about a first axis transverse to the longitudinal axis of the shaft; and a second joint drivable by a second pair of drive elements; and and a second set of pulleys, wherein each pulley in the second set of pulleys is rotatable about an offset axis that is offset from the first axis in a direction transverse to a longitudinal direction of the shaft when the surgical instrument is in a straight configuration in which the first end effector element is aligned with the shaft, and the second set of pulleys is positioned between the first set of pulleys and an instrument interface end of the shaft, wherein the length of the second pair of drive elements remains the same regardless of rotation of the end effector element about the first joint.

2. The robotic surgical instrument according to claim 1, wherein: The second joint allows the first end effector element to rotate about a second axis that is transverse to the first axis.

3. The robotic surgical instrument according to claim 1 or 2, wherein: Each pulley of the second set of pulleys is rotatable about the offset axis parallel to the first axis.

4. The robotic surgical instrument according to claim 3, wherein: The second set of pulleys includes a first pulley rotatable about a third axis and includes a second pulley rotatable about a fourth axis, the third axis being offset from the fourth axis.

5. The robotic surgical instrument according to claim 1 or 2, wherein: The distal end of the shaft is connected to the hinge, and the proximal end of the shaft is connected to a drive mechanism for driving the first and second pairs of drive elements, wherein the second set of pulleys is located between the first set of pulleys and the proximal end of the shaft.

6. The robotic surgical instrument according to claim 5, wherein: The second set of pulleys is located inside the shaft.

7. The robotic surgical instrument according to claim 5, wherein: The hinge includes the second set of pulleys.

8. The robotic surgical instrument according to claim 1 or 2, wherein: The first set of pulleys includes a first pulley and a second pulley located on opposite sides of the first joint; and The second set of pulleys includes a first pulley and a second pulley located on opposite sides of the first joint.

9. The robotic surgical instrument according to claim 8, wherein: The second pair of drive elements is constrained to move about opposite sides of the first and second pulleys of the first set of pulleys.

10. The robotic surgical instrument according to claim 8, wherein: The second pair of drive elements is constrained to move about opposite sides of the first and second pulleys of the second set of pulleys.

11. The robotic surgical instrument according to claim 1 or 2, further comprising a second end effector element, wherein: The articulated portion further comprises a third joint drivable by a third pair of drive elements, the third pair of drive elements being constrained to move about the pulley arrangement; The rotation of the first end effector element about the first axis is defined by a limiting rotation angle relative to the longitudinal axis, the limiting rotation angle being the angle at which the first pair of drive elements are at maximum travel about the first joint; and The second set of pulleys is positioned relative to the first set of pulleys such that at the extreme rotational angles, the third pair of drive elements remain in contact with both the first and second sets of pulleys.

12. The robotic surgical instrument according to claim 11, wherein: The third joint allows the second end effector element to rotate about a second axis.

13. The robotic surgical instrument according to claim 11, wherein: Each pulley in the first and second pulley groups includes a pair of pulley elements, the pair of pulley elements including an inner pulley element and an outer pulley element, the inner pulley element is located between the outer pulley element and the first joint, and each pulley element includes a groove for accommodating a drive element.

14. The robotic surgical instrument according to claim 13, wherein: the second pair of drive elements being constrained to move about the inner pulley element of the first pulley of the second set of pulleys and the outer pulley element of the second pulley of the second set of pulleys; and The third pair of drive elements is constrained to move about the outer pulley element of the first pulley of the second set of pulleys and the inner pulley element of the second pulley of the second set of pulleys.

15. The robotic surgical instrument of claim 13, wherein: the second pair of drive elements being constrained to move about the inner pulley element of the first pulley of the first set of pulleys and the outer pulley element of the second pulley of the first set of pulleys; and The third pair of drive elements is constrained to move about the outer pulley element of the first pulley of the first set of pulleys and the inner pulley element of the second pulley of the first set of pulleys.

16. The robotic surgical instrument according to claim 15, wherein: For each pulley, one pulley element of the pair of pulley elements abuts the other pulley element of the pair of pulley elements.

17. The robotic surgical instrument according to claim 11, wherein: The second pair of drive elements and the third pair of drive elements have the same length for all rotational angles of the first end effector element relative to the longitudinal axis.

18. The robotic surgical instrument according to claim 11, wherein: The first and second end effector elements are opposed first and second jaws of an end effector.

19. The robotic surgical instrument according to claim 1 or 2, wherein: These pairs of drive elements include flexible portions and spokes.

20. The robotic surgical instrument according to claim 1 or 2, wherein: These pairs of driving elements are cables.

21. The robotic surgical instrument according to claim 1 or 2, wherein: These resist compression and tension forces on the drive elements.

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