GB2537108A

GB2537108A - Thread dispensing tool

Info

Publication number: GB2537108A
Application number: GB1505523.9A
Authority: GB
Inventors: James Randle Steven
Original assignee: Cambridge Medical Robotics Ltd
Current assignee: Cambridge Medical Robotics Ltd
Priority date: 2015-03-31
Filing date: 2015-03-31
Publication date: 2016-10-12
Anticipated expiration: 2035-03-31
Also published as: GB201505523D0; GB2537108B

Abstract

A surgical robot tool has a thread driver 66 for driving suture thread 65 from a thread holder 64 through the hollow lumen of a needle 63 at an end effector 62 disposed at a distal end of an elongate hollow shaft 60. The thread passes between a friction pad 69 and leaf spring 70 in a hollow member 60 with a flag 71 driven by a drive tab of a robot arm to pay out the thread in one direction, preferably during insertion and withdrawal of the needle during suturing operations. The robot arm has an interface fastening structure for attachment to different surgical tools and a drive mechanism with extending linkage configured to provide mechanical drive to the flag 71 of a tool fastened to the arm interface.

Description

THREAD DISPENSING TOOL

This invention relates to a tool usable for dispensing thread, for example suturing thread.

Laparoscopic surgery can be conducted manually or using surgical robots. Suturing is one action that is commonly performed as part of a laparoscopic procedure, for example to close cuts or lesions in tissue that is being operated on. The tissue to be sutured may be on the surface of a patient's body, or it may be internal to the patient. When internal suturing is being carried out by laparoscopic techniques the path to access the suturing site is normally very confined, meaning that there is limited mobility of surgical instruments at the site. This makes it difficult to perform suturing in laparoscopic surgery. When student surgeons are being taught to perform laparoscopic surgery the skills required for suturing often occupy a substantial part of the training time.

The conventional way to perform suturing in laparoscopic surgery is to pass suturing thread through the eye of a suturing needle outside the body, pass the threaded needle into the patient's body through a trocar and then work the suturing needle through the tissue to be sutured. To work the needle through the tissue it is grasped by a needle driver once it has passed through the trocar and then pushed into the tissue from the entry side of the suture. Then the needle can be released and the needle driver repositioned to pull the needle through from the exit side of the stitch, or a second instrument can be used to pull the needle without the needle driver first letting go of the needle. These manoeuvres involve a considerable amount of dexterity since the needle must be grasped in a suitable orientation and it must be kept under control as it is used when the surgeon is working using elongate tools and potentially in an awkward position.

Similar techniques are used in robotic laparoscopy, although it has been proposed that robotic suturing could be automated. See, for example: "Autonomous Suturing using Minimally Invasive Surgical Robots" (H Kang and J Wen, Proc. 2000 IEEE Int. Conf. on Control Applications).

The i-Stitch, available from AMI GmbH, is an alternative design of manual suturing device. It comprises a hollow rod. At the distal end of the hollow rod is a curved element which terminates in a thread catcher. The thread catcher is spaced from the distal end of the rod but aligned with the bore in the rod. Inside the hollow rod is a hollow needle which can move longitudinally within the rod so that its distal tip can meet the thread catcher. To perform suturing, thread is fed down the lumen of the hollow needle, the tip of the needle is aligned with the distal end of the hollow rod and the tool is positioned so that the tip of the needle is on one side of the tissue to be sutured and the thread catcher is on the other side. Then the needle is moved down the hollow rod so as to pierce the tissue and bring the suturing thread to the thread catcher. The thread catcher grips the thread extending from the tip of the needle, and the needle can be withdrawn. The fact that the thread is held by the thread catcher means that the thread is drawn through the needle as the needle is withdrawn, leaving a length of thread passing through the tissue.

There is a need for an improved way of suturing using a surgical robot.

According to one aspect of the present invention there is provided a surgical robot system comprising: a robot arm having an arm interface thereon for attachment to surgical tools, the arm interface having a fastening structure whereby a tool can be fastened to the arm interface and a drive mechanism configured to provide mechanical drive to a tool fastened to the arm interface; a first surgical tool having: (i) an end effector comprising at least one mobile external member for performing a surgical procedure, (ii) a first tool interface configured for fastening to the arm interface, and (iii) a linkage extending from the first tool interface to the mobile external member, the first tool interface having a first drive coupling operably connected to the linkage such that motion of the mobile member can be driven from the drive coupling; and a second surgical tool having: (i) an elongate hollow shaft, (ii) an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, (iii) a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle and (iv) a second tool interface configured for fastening to the arm interface, the second tool interface having a second drive coupling operably connected to the thread driver such that motion of the mobile member can be driven from the drive coupling; the first and second tool interfaces being configured such that when either tool interface is fastened to the arm interface its drive coupling can couple to the drive mechanism of the arm whereby the respective drive coupling can be driven from the drive mechanism of the arm.

The drive mechanism may comprise a first connector member mounted on a segment of the arm. Each drive coupling may comprise a respective second connector member configured for physically mating with the first connector member when the respective tool interface is fastened to the arm interface.

The first connector member may be linearly moveable with respect to the said segment. The first connector member may be rotationally moveable with respect to the said segment. The first connector member may be both linearly and rotationally moveable with respect to the said segment.

The thread driver may be configured such that reciprocal linear motion of the thread driver with respect to the shaft of the second tool causes thread to be driven through the interior of the shaft in a direction towards the distal end of the needle. The thread driver may be configured such that reciprocal linear motion of the thread driver with respect to the shaft of the second tool causes thread to undergo net motion through the interior of the shaft in a direction towards the distal end of the needle.

The shaft of the second tool may comprise a cavity containing a length of thread The mobile external member may be a jaw.

The drive mechanism may comprise a drive unit for generating motion to be conveyed to the tool.

The drive mechanism may be an electric motor.

The surgical robot system may comprise a controller for controlling motion of the arm and the drive mechanism. The controller may be configured for a mode of operation in which, when the second tool is held on the arm and the arm is being operated so as to move the needle in a direction away from the distal end of the needle, it controls the drive mechanism to cause the thread driver automatically to advance thread through the needle at the same rate as the distal end of the needle is being moved.

According to a second aspect of the present invention there is provided a method for operating a surgical robot having an articulated arm and a surgical tool mounted to the arm, the surgical tool having an elongate hollow shaft, an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, and a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle, the method comprising, with the needle passing into a bodily tissue operating the arm so as to withdraw the distal tip of the needle through the tissue, and simultaneously operating the thread driver to advance thread through the distal tip of the needle at substantially the same rate as the distal tip is being withdrawn.

The surgical robot may comprises a controller. The method may comprise causing the controller to automatically operate the thread driver to advance thread at the said rate.

The controller may compute the said rate in dependence on the motion of the arm and/or information defining one or more dimensions of the tool. Those dimensions may include information defining the distance of the distal tip of the needle from one or more joints of the arm.

The surgical robot may comprise a user interface. The robot is responsive to operation of the user interface, e.g. manually, by an operator to guide motion of the arm. The method may comprise guiding the arm to withdraw the distal tip of the needle through the tissue by means of that user interface.

According to a third aspect of the present invention there is provided a surgical robot having: an articulated arm; a surgical tool mounted to the arm, the surgical tool having an elongate hollow shaft, an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, and a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle; and a controller, the controller being configurable to, with the needle passing into a bodily tissue and the being operated so as to withdraw the distal tip of the needle through the tissue, simultaneously operate the thread driver to advance thread through the distal tip of the needle at substantially the same rate as the distal tip is being withdrawn.

The controller may be configured to compute the said rate in dependence on the motion of the arm and information defining one or more dimensions of the tool.

The surgical robot may comprise a user interface and the robot may be responsive to operation of the user interface by an operator to guide motion of the arm.

The present invention will now be described by way of example with reference to the accompanying drawings.

Figure 1 illustrates a surgical robot arm.

Figure 2 shows an instrument mount of the arm of figure 1. Figure 3 shows an end view of the instrument mount of figure 2. Figure 4 shows a drive mechanism of the arm of figure 1. Figure 5 shows a first instrument operable with the arm of figure 1.

Figure 6 shows a second instrument operable with the arm of figure 1.

Figure 7 is a cut away partial view of the tool of figure 6.

Figure 8 shows an alternative configuration for the needle of the instrument of figure 6.

Figure 1 shows the arm of a surgical robot. Figures 5 and 6 show tools that can be attached to a tool interface of the arm. The tool of figure 5 has a pair of jaws that are movable, e.g. for carrying out surgical procedures when the working end of the tool is in a patient. The tool of figure 6 has a hollow needle and a thread driver that is operable to feed thread in a distal-going direction through the lumen of the needle, e.g. when the needle is in a patient. The tools of figures 5 and 6 are configured so that either of them can be attached to the same tool interface on the arm and so that (a) when the tool of figure 5 is attached to the arm a driving element on the tool interface of the arm can actuate motion of at least one of the jaws, and (b) when the tool of figure 6 is attached to the arm the same driving element on the tool interface of the arm can actuate the thread driver to advance thread through that tool. In a surgical procedure multiple arms of the type shown in figure 1 may be engaged simultaneously, each with a respective tool attached.

Figure 1 shows an arm of a surgical robot. The arm has a base 1 which can be positioned at a suitable location near an operating table for performing a surgical procedure on a patient. The arm has a number of rigid members or segments 2, 3, 4, 17 along its length, and a number of joints 5-12 which allow the rigid members to be moved relative to each other to position the distal end 13 of the arm in a desired location. An instrument 14 is mounted to the distal end of the arm. The instrument comprises an end effector 15 at the distal end of an elongate shaft 16. In use, the instrument can be inserted into the body of a patient and a surgical task can be performed by the end effector. A surgeon can operate the joints of the robot and the end effector from an operating station 84 which is communicatively linked to motors and position/force sensors provided at the joints of the arm.

Figures 2 and 3 show the distal end 13 of the arm in more detail. Member 4 of the arm is attached by a wrist joint 11 to a mounting block 17 which constitutes the terminal member or segment of the arm. The mounting block is configured to attach to a surgical instrument. In this example the wrist joint is a simple rotational joint, but it could be a more complex arrangement, for example as described in our co-pending application PCT/GB2014/053523. The mounting block 17 defines a channel 18 of U-shaped cross-section. The channel is intended to receive the proximal end of a surgical instrument. A number of drive tabs 19 protrude into the channel. In this example there are three drive tabs arranged circumferentially around the side wall of the channel. Each drive tab extends into the channel 18 through a window 21 in the side wall. The window is elongate along the length of the channel. Inside the body of the mounting block, each drive tab is attached to a linear actuator which can drive the tab to move in the direction of elongation of the windows, as indicated by arrow 20. Claws 22 extend into the channel for mechanically engaging a tool to retain the tool in the channel.

Figure 4 illustrates an example of the mechanical actuator arrangement that can be used to drive linear motion of the drive tabs. It comprises a lead screw 30 which can be driven about its longitudinal axis 31 by a motor 32. A nut structure 33 is threaded on to the lead screw and the tab 19 is attached to the nut structure. Since the tab is restrained from rotating about the axis of the lead screw by the lateral edges of the window 21, through which it protrudes, the tab moves longitudinally with respect to the lead screw as the lead screw rotates. The drive tabs could be driven linearly by other means, for example pneumatic or hydraulic pistons.

Figure 5 shows a first tool that can be attached to the arm. The tool of figure 5 is a grasping tool. The tool comprises an elongate shaft 40. At the proximal end of the shaft is an attachment structure shown generally at 41 for mating with the mounting block of the arm. At the distal end of the shaft is an end effector shown generally at 42. The end effector comprises a pair of opposable jaws 43, 44 which can be operated to grip an object therebetween. Each jaw can pivot relative to the shaft 40 about a respective pivot 45, 46, allowing the jaws to meet. The position of each jaw is controlled by a respective endless loop of filament 47, 48. Each loop of filament passes around a tensioning pulley 49, 50 at the proximal end of the shaft, and then around a spool attached to the respective jaw at the jaw's rotation axis. Each filament loop is attached to a respective flag 51, 52 which protrudes radially out of the exterior wall of the shaft at its proximal end. Motion of the flag along the longitudinal axis of the shaft causes the loop to turn around the pulley, also turning the spool. To ensure the spool's rotation is linked to the position of the filament the filament can be wound multiple times around the spool, or can be bonded to it. Thus, the rotational position of jaw 43 is dependent on the longitudinal position of flag 51 and the rotational position of jaw 44 is dependent on the longitudinal position of flag 52.

The tool comprises recesses in the outer surface of its distal end into which claws 22 can clip to retain the tool in place in the mounting block.

Flags 51 and 52 are sized and positioned so that when the tool is mounted in the mounting block, clipped into the claws 22 so as to be held in place, the flags will fit snugly into recesses 23 in the drive tabs. In this way, the longitudinal position of each flag is dependent on the position of the respective drive tab, and each jaw can be moved to a desired position by the drive means of its respective drive tab.

A further filament loop (not shown) extends from a third flag 53 to a mechanism associated with a joint 54 at the distal end of the shaft. The joint 54 separates the majority of the length of the shaft from a tip portion 55 of the shaft and enables the tip portion to be rotated about the longitudinal axis of the shaft in dependence on the position of the flag 53. Flag 53 can also mate with a drive tab on the arm, allowing the rotational configuration of the tip portion to be controlled by the drive means to which that drive tab is coupled.

In summary, therefore, the elongate grasping tool of figure 5 can be attached to the mounting block in such a way that its mechanical configuration and operation can be controlled by drives in the arm.

Figure 6 shows a second tool. The tool of figure 5 is a threading tool. The tool comprises an elongate shaft 60. At the proximal end of the shaft is an attachment structure shown generally at 61 for mating with the mounting block of the arm. At the distal end of the shaft is an end effector 62. The end effector comprises a hollow needle 63 which extends from the distal tip of the shaft 60. In the example of figure 6 the needle is straight, but it could be curved as shown in figure 8. A hollow lumen extends the length of the needle.

Inside the second tool is a thread holder 64. The thread holder holds a length of suturing thread 65. The thread holder could be a receptacle such as a box or chamber into which the thread can be coiled or looped. Alternatively the thread holder could be a spool onto which the thread is wound. The thread 65 extends from the thread holder through a thread driver 66 (see figure 7) and then through a hollow passage along the interior of the shaft until it reaches the proximal end of needle 63. The thread passes through the lumen of the needle and is exposed at the distal end of the needle, as illustrated at 67.

The tool of figure 6 comprises recesses in the outer surface of its distal end into which the claws 22 can clip to retain the tool in place in the mounting block.

Figure 7 is a cut-away view of the tool of figure 6, showing the thread holder 64 and the thread driver 66. The thread driver comprises a hollow member 68 which surrounds the thread 65. Inside the hollow member is a friction pad 69 and a spring 70. The spring 70 is a leaf spring which extends from the interior wall of the hollow member 68 and presses against the friction pad 69. The thread passes between the spring 70 and the friction pad 69. A flag 71 is attached to the hollow member 68 and extends through a window 72 in the outer wall of the tool. As with the flags of the tool of figure 5, flag 71 is sized and positioned so that when the tool is mounted in the mounting block 17 of the arm, and held by clasps 22, the flag 71 will fit snugly into a pocket 23 in one of the drive tabs 19, whereby the flag 71 can be driven along the longitudinal axis of the tool.

The leaf spring 70 is directed with its free end towards the distal end of the instrument. As a result, when the flag 71 is driven by the arm towards the distal end of the tool the tip of the leaf spring will dig to some extent into the thread 65, gripping the thread and causing it to move towards the distal end of the tool. The strength of the spring 70 is selected so that when the flag 71 is driven by the arm towards the proximal end of the tool the leaf spring will slip over the thread 65 and will not draw it towards the proximal end of the tool. Thus, reciprocal motion of the thread driver can draw out the thread 65 from the thread holder 64 and cause the thread to pay out of the distal tip of the needle 63. Other designs of one-way drive mechanism for the thread could be used.

The thread holder 64 could be mounted inside the shaft of the instrument of figures 6 and 7, or could be attached to the outside of the shaft. The free thread could just be loose inside the shaft of the instrument, in which case the outer wall of the tool shaft itself could act as the thread holder.

To control the motion of the thread 65 through the tool, and in particular to prevent it from buckling when driven by the thread driver, it may be confined in a narrow guide tube. The narrow tube may have an internal diameter less than 10 or more preferably less than 5 or 3 times the external diameter of the thread. The guide tube may extend substantially along the full extent of the shaft 60 between the thread driver 66 and the needle 63.

The same mechanical interface can be used to hold either of the tools of figures 6 and 8. The same drive mechanism on the arm can be used to drive the motion of either of the tools of figures 6 and 8. In the example shown in the figures, drive is transferred to the tools by linear motion of the drive elements 19 on the arm. Such linear motion could be parallel locally to an interface between the tool and the arm, as shown in the figures, or perpendicular: i.e. into or out of the tool. In other examples the motion could be transferred by rotational drive. The motion could be transferred by positive engagement between the drive mechanisms on the arm, as shown in the figures, or by frictional engagement or by contactless force transfer, for example by magnetic engagement.

The instrument shown in figure 5 has a single thread driver which can be reciprocated to advance thread through the needle. A second thread driver which is similar to the first but reversed could also be provided, in series with the first. The second thread driver is arranged so that it can be reciprocated to retract thread in the direction from the distal end of the needle.

The tool of figure 6 can be used for performing suturing in a laparoscopic procedure. The tool is introduced into the body of a patient through a port/trocar and inserted until the end effector reaches the surgical site. At the surgical site it may be desired to form a suture in one or more elements of tissue. The needle 63 is manipulated by means of the surgical arm to which it is attached so as to pass through the tissue to be sutured. Once the needle has passed through the tissue to be sutured the distal end of the needle will be free of that tissue and protruding into a body cavity of the patient. At that point either of two methods can be used to lay the thread in the pathway formed by the needle.

1. In a first method the thread driver can be operated to advance the suture thread, if necessary, so that it extends out of the distal end of the needle and into the body cavity. A tool of the type shown in figure 5 may be attached to a second robot arm and also inserted into the patient's body so that its end effector is at the surgical site.

That tool can be used to grasp the free end of the thread. Then the needle can be withdrawn from the tissue by operating the arm to which it is attached so as to reverse the needle along the pathway formed in the tissue to be sutured. Since the free end of the thread is held by the grasping tool, the action of withdrawing the needle from the pathway pulls further thread from the thread holder. Once the needle is withdrawn from the pathway a length of thread is left in the pathway. The thread can then be cut, using a suitable tool, at a point between the tissue and the distal end of the needle.

2. In a second method, the thread driver can be operated synchronously with the withdrawal of the needle from the pathway. Preferably a control system of the robot is configured to cause the thread driver to operate automatically so as to advance thread at the same rate that the needle is being withdrawn. This process leaves the thread in the pathway without the need for the free end of the thread to be held by another tool. A further advantage of this process is that an exposed length of the thread is not held under tension in the pathway, which could result in it damaging tissue around the pathway, particularly if the pathway is curved. Once the needle has been withdrawn from the pathway the thread can be cut, using a suitable tool, at a point between the tissue and the distal end of the needle. The instrument may comprise an identifier, for example an RFID chip, which is readable by the robot so as to identify the instrument. The identifier may directly specify the dimensions and configuration of the instrument, or it may provide information that specifies the model of the instrument, from which the controller can look up the dimensions and the configuration of the instrument. Once the details of the instrument are known by the controller the controller can compute the rate of travel of the tip of the needle as the arm and/or any articulation of the instrument are moved. The thread can then be dispensed at the same rate. The controller may be configured to automatically dispense thread in this way only when the tip is being moved in a direction opposite the direction in which it is pointing.

After the thread has been cut, leaving a length of thread passing through the tissue, the ends of the thread can be knotted together, attached together with a coupler, or interengaged by means of barbs built into the thread.

In the processes discussed above, the thread to be passed through the tissue can be fully within the threading tool, when it is passed through the tissue. This can help to minimise the size of the channel through the tissue that is formed when the needle is inserted, and avoid disruption to the sides of the channel from the thread. This is especially significant when the thread is a barbed thread.

As indicated above, the surgical robot could be configured to automatically pay out thread from the tool of figure 5 at the same rate as the tool is being withdrawn from a passageway in a patients tissue. In figure 1 unit 80 indicates a control system for the robot arm. The control system comprises a control unit 81 having a processor 82 and a non-volatile memory 83; and a user interface 84 comprising a motion input device 85 and a number of configuration switches 86. The non-volatile memory 83 stores in a non-transient way code that can be executed by the processor 82 to cause it to control the arm to operate in a desired manner. Outputs from the processor 82 drive (i) motors (e.g. 87) which move the joints of the arm and (H) the actuators which move the drive tabs 19. The motion input device 85 could be a joystick or the like. A surgeon can use the motion input device to provide inputs to the processor which indicate desired motions of the arm. By executing code stored in memory 83 the processor 82 interprets those inputs and controls the arm accordingly. The configuration switches enable the surgeon to select various operating modes of the arm. In one operating mode of the arm the processor determines the speed of movement of the arm in a direction following the path of the needle (which may be straight or curved) with a sense towards the proximal end of the needle, and automatically operates the thread driver to advance thread from the needle at that same speed. In another operating mode of the arm the processor could be responsive to a first operation of one of the configuration switches to store the position of the arm, and to a second operation of a configuration switch to automatically withdraw the arm to that stored position with along a path aligned with the needle, whether straight or curved whilst simultaneously advancing the thread at the same rate as the needle is withdrawn. With this system, the operator positions the needle near the location at which it is to penetrate the tissue and make the first operation of a switch. Then the surgeon advances the needle through the tissue until its tip is exposed on the far side of the tissue. Then the surgeon makes the second operation of a switch and the controller automatically withdraws the needle through the passage in the tissue and pays out the thread at the same rate.

Other tools having mobile elements could substitute for, or be used in addition to, the tool of figure 5. These could include cutting tools having an articulated cutting element such as a blade, single-jawed tools, and articulated tools adapted for pushing or pulling body tissue.

The instrument of figure 5 could be used for non-surgical purposes. For example, it could be used for passing dental floss between teeth in a cosmetic procedure.

The suturing tool may be sold as a disposable unit with the thread sealed inside it. Alternatively, the thread could be sold in disposable sealed canisters that clip to the instrument, with each canister lasting either one procedure or longer.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

CLAIMS1. A surgical robot system comprising: a robot arm having an arm interface thereon for attachment to surgical tools, the arm interface having a fastening structure whereby a tool can be fastened to the arm interface and a drive mechanism configured to provide mechanical drive to a tool fastened to the arm interface; a first surgical tool having: (i) an end effector comprising at least one mobile external member for performing a surgical procedure, (ii) a first tool interface configured for fastening to the arm interface, and (iii) a linkage extending from the first tool interface to the mobile external member, the first tool interface having a first drive coupling operably connected to the linkage such that motion of the mobile member can be driven from the drive coupling; and a second surgical tool having: (i) an elongate hollow shaft, (ii) an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, (iii) a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle and (iv) a second tool interface configured for fastening to the arm interface, the second tool interface having a second drive coupling operably connected to the thread driver such that motion of the mobile member can be driven from the drive coupling; the first and second tool interfaces being configured such that when either tool interface is fastened to the arm interface its drive coupling can couple to the drive mechanism of the arm whereby the respective drive coupling can be driven from the drive mechanism of the arm.
2. A surgical robot system as claimed in claim 1, wherein the drive mechanism comprises a first connector member mounted on a segment of the arm, and each drive coupling comprises a respective second connector member configured for physically mating with the first connector member when the respective tool interface is fastened to the arm interface.
3. A surgical robot system as claimed in claim 2, wherein the first connector member is linearly moveable with respect to the said segment.
4. A surgical robot system as claimed in claim 2, wherein the first connector member is rotationally moveable with respect to the said segment.
5. A surgical robot system as claimed in claim 3, wherein the thread driver is configured such that reciprocal linear motion of the thread driver with respect to the shaft of the second tool causes thread to be driven through the interior of the shaft in a direction towards the distal end of the needle.
6. A surgical robot system as claimed in any preceding claim, wherein the shaft of the second tool comprises a cavity containing a length of thread
7. A surgical robot system as claimed in any preceding claim, wherein the mobile external member is a jaw.
8. A surgical robot system as claimed in any preceding claim, wherein the drive mechanism comprises a drive unit for generating motion to be conveyed to the tool.
9. A surgical robot system as claimed in claim 8, wherein the drive mechanism is an electric motor.
10. A surgical robot system as claimed in any preceding claim, comprising a controller for controlling motion of the arm and the drive mechanism, the controller being configured for a mode of operation in which, when the second tool is held on the arm and the arm is being operated so as to move the needle in a direction away from the distal end of the needle, it controls the drive mechanism to cause the thread driver automatically to advance thread through the needle at the same rate as the distal end of the needle is being moved.
11. A surgical robot system substantially as herein described with reference to the accompanying drawings.
12. A method for operating a surgical robot having an articulated arm and a surgical tool mounted to the arm, the surgical tool having an elongate hollow shaft, an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, and a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle, the method comprising, with the needle passing into a bodily tissue operating the arm so as to withdraw the distal tip of the needle through the tissue, and simultaneously operating the thread driver to advance thread through the distal tip of the needle at substantially the same rate as the distal tip is being withdrawn.
13. A method as claimed in claim 12, wherein the surgical robot comprises a controller and the method comprises causing the controller to automatically operate the thread driver to advance thread at the said rate.
14. A method as claimed in claim 13, comprising the controller computing the said rate in dependence on the motion of the arm and information defining one or more dimensions of the tool.
15. A method as claimed in any of claims 12 to 14, wherein the surgical robot comprises a user interface and the robot is responsive to operation of the user interface by an operator to guide motion of the arm, and the method comprises guiding the arm to withdraw the distal tip of the needle through the tissue by means of that user interface.
16. A surgical robot having: an articulated arm; a surgical tool mounted to the arm, the surgical tool having an elongate hollow shaft, an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, and a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle; and a controller, the controller being configurable to, with the needle passing into a bodily tissue and the being operated so as to withdraw the distal tip of the needle through the tissue, simultaneously operate the thread driver to advance thread through the distal tip of the needle at substantially the same rate as the distal tip is being withdrawn.
17. A surgical robot as claimed in claim 16, the controller being configured to compute the said rate in dependence on the motion of the arm and information defining one or more dimensions of the tool.
18. A surgical robot as claimed in claim 16 or 17, the surgical robot comprising a user interface and the robot being responsive to operation of the user interface by an operator to guide motion of the arm.Amendments to the claims have been made as follows:CLAIMS1. A surgical robot system comprising: a robot arm having an arm interface thereon for attachment to surgical tools, the arm interface having a fastening structure whereby a tool can be fastened to the arm interface and a drive mechanism configured to provide mechanical drive to a tool fastened to the arm interface; a first surgical tool having: (i) an end effector comprising at least one mobile external member for performing a surgical procedure, (ii) a first tool interface configured for fastening to the arm interface, and (iii) a linkage extending from the first tool interface to the mobile external member, the first tool interface having a first drive coupling operably connected to the linkage such that motion of the mobile external member can be driven from the first drive coupling; and a second surgical tool having: (i) an elongate hollow shaft, (ii) an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, (iii) a cr) thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle and (iv) a second tool interface configured for fastening to O the arm interface, the second tool interface having a second drive coupling operably 0C3) connected to the thread driver such that motion of the thread driver can be driven from the second drive coupling; the first and second tool interfaces being configured such that when either tool interface is fastened to the arm interface its drive coupling can couple to the drive mechanism of the arm whereby the respective drive coupling can be driven from the drive mechanism of the arm.2. A surgical robot system as claimed in claim 1, wherein the drive mechanism comprises a first connector member mounted on a segment of the arm, and each drive coupling comprises a respective second connector member configured for physically mating with the first connector member when the respective tool interface is fastened to the arm interface.3. A surgical robot system as claimed in claim 2, wherein the first connector member is linearly moveable with respect to the said segment.4. A surgical robot system as claimed in claim 2, wherein the first connector member is rotationally moveable with respect to the said segment.5. A surgical robot system as claimed in claim 3, wherein the thread driver is configured such that reciprocal linear motion of the thread driver with respect to the shaft of the second tool causes thread to be driven through the interior of the shaft in a direction towards the distal end of the needle.6. A surgical robot system as claimed in any preceding claim, wherein the shaft of the second tool comprises a cavity containing a length of thread 7. A surgical robot system as claimed in any preceding claim, wherein the mobile external member is a jaw. cr)mechanism comprises a drive unit for generating motion to be conveyed to the tool.O 9. A surgical robot system as claimed in claim 8, wherein the drive mechanism is an electric motor.O10. A surgical robot system as claimed in any preceding claim, comprising a controller for controlling motion of the arm and the drive mechanism, the controller being configured for a mode of operation in which, when the second tool is held on the arm and the arm is being operated so as to move the needle in a direction away from the distal end of the needle, it controls the drive mechanism to cause the thread driver automatically to advance thread through the needle at the same rate as the distal end of the needle is being moved.11. A surgical robot system substantially as herein described with reference to the accompanying drawings.8. A surgical robot system as claimed in any preceding claim, wherein the drive 12. A surgical robot having: an articulated arm; a surgical tool mounted to the arm, the surgical tool having an elongate hollow shaft, an end effector comprising a needle having a hollow lumen disposed at a distal end of the shaft, and a thread driver for driving thread through the interior of the shaft in a direction towards the distal end of the needle; and a controller, the controller being configurable to, with the needle passing into a bodily tissue and the being operated so as to withdraw the distal tip of the needle through the tissue, simultaneously operate the thread driver to advance thread through the distal tip of the needle at substantially the same rate as the distal tip is being withdrawn.13. A surgical robot as claimed in claim 12, the controller being configured to compute the said rate in dependence on the motion of the arm and information defining one or more dimensions of the tool.14. A surgical robot as claimed in claim 12 or 13, the surgical robot comprising a user O interface and the robot being responsive to operation of the user interface by an a) operator to guide motion of the arm.