DEVICE FOR IMPROVING THE ACCURACY OF MANUAL OPERATIONS

Abstract

A hand held robotic system that remains stiff so long as it is operating within allowed limits, but which become actively controlled once the operator exceeds those limits. The system thus corrects deviations by more than a predetermined amount of the operator's hand motions, so that the tool remains in the allowed region even when the operator's hand deviates from the planned trajectory. The pose and path of the robotic operating head is ascertained by means of a navigation or tracking system, or by means of a proximity device to measure the closeness of the operating head to a damage sensitive feature. As the tool deviates from its predetermined path or pose, or comes too close to the hazardous area, the robot control acts to move the tool back to its predetermined pose or path, or away from the hazardous region, independently of user's hand movement.

Claims

1. A surgical robotic system, comprising: a robotic operating head having a robotic mechanism configured to engage a surgical tool; and a controller that controls the robotic mechanism according to one or more signals received from a tracking system, the tracking system comprising: a tracking target configured to be mounted on an external object and to indicate a pose of the external object when mounted thereon; and a tracker head mounted on the robotic operating head, the tracker head configured to detect the tracking target and enable the tracking system to provide information regarding a pose of the surgical tool relative to the external object.

2. The surgical robotic system according to claim 1, wherein the external object is a bone of a patient and the surgical tool is configured to operate on the bone.

3. The surgical robotic system according to claim 1, wherein a proximity of the tracker head to the tracking target enables the tracking system to provide the information while reducing line of sight issues between the tracker head and the tracking target.

4. The surgical robotic system according to claim 1, wherein a proximity of the tracker head to the tracking target enables the tracking system to provide the information, the information having a higher accuracy than corresponding pose information from a system having a remote tracker head.

5. The surgical robotic system according to claim 1, wherein the robotic operating head includes a platform, and wherein the tracker head is mounted on the platform.

6. The surgical robotic system according to claim 5, wherein the platform forms part of a distal end portion of the robotic mechanism.

7. The surgical robotic system according to claim 6, wherein the surgical tool engages with the robotic mechanism at the distal end portion of the robotic mechanism.

8. The surgical robotic system according to claim 1, wherein the robotic operating head comprises a handle that enables an operator to hold the robotic operating head.

9. The surgical robotic system according to claim 8, wherein the tracker head is mounted on the handle.

10. The surgical robotic system according to claim 1, wherein the tracking system comprises a proximity sensor for determining a distance of the surgical tool from a damage-sensitive region of the external object.

11. The surgical robotic system according to claim 10, wherein the proximity sensor comprises a blood flow sensor or a neural monitor.

12. The surgical robotic system according to claim 1, wherein the tracking system detects a position of at least one of a platform of the robotic operating head or the surgical tool.

13. The surgical robotic system according to claim 1, wherein the robotic operating head includes a platform attached to the robotic mechanism and configured to engage the surgical tool.

14. The surgical robotic system according to claim 13, wherein the controller is configured to control the robotic mechanism to selectively move the platform.

15. The surgical robotic system according to claim 14, wherein the one or more signals correspond to a position of the surgical tool relative to an allowed region, wherein: (i) when the one or more signals indicate that the surgical tool is within the allowed region, the robotic mechanism remains in an inactive rigid mode in which the robotic mechanism does not move the platform relative to a handle of the robotic operating head; and (ii) when the one or more signals indicate that the surgical tool has reached a forbidden region, the controller automatically causes the robotic mechanism to move the platform relative to the handle such that the surgical tool remains in the allowed region.

16. The surgical robotic system according to claim 15, wherein, in (ii), the controller causes the robotic mechanism to move the platform relative to the handle to maintain an axis of the surgical tool while an axis of the handle varies, to keep the surgical tool in the allowed region.

17. A surgical robotic system, comprising: a tracking system comprising: a tracking target configured to be mounted on an external object and to indicate a pose of the external object when mounted thereon; and a tracker head mounted on a robotic operating head configured to engage a surgical tool, the tracker head configured to detect the tracking target and enable the tracking system to provide information regarding a pose of the surgical tool relative to the external object; and a controller that controls the robotic operating head according to one or more signals received from the tracking system.

18. The surgical robotic system according to claim 17, wherein the robotic operating head comprises: a robotic mechanism; and a platform attached to the robotic mechanism and configured to engage the surgical tool.

19. The surgical robotic system according to claim 18, wherein the controller is configured to control the robotic mechanism to selectively move the platform.

20. A surgical robotic system, comprising: a handheld robotic operating head comprising: a platform configured to engage a surgical tool; a robotic mechanism configured to selectively move the platform; and a handle that enables an operator's hand to grip and maneuver the robotic operating head; and a base positioned between the robotic mechanism and the handle, wherein the platform is moveable relative to the base; and a tracking system comprising: a tracking target configured to be mounted on an external object and to indicate a pose of the external object when mounted thereon; and a tracker head mounted on the robotic operating head, the tracker head configured to detect the tracking target and enable the tracking system to provide information regarding a pose of the surgical tool relative to the external object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0037] FIG. 1 shows an exemplary hand-held robotic surgical system as described in this disclosure, for shaping a subject's bone;

[0038] FIG. 2 shows the operation of the robotic controller in correcting for deviation of the surgeon's hand from a predetermined surgical plan for shaping of the bone;

[0039] FIG. 3 shows an application of the hand-held robot of FIG. 1, for performing a targeted procedure in soft tissue of a subject close to a sensitive anatomical structure, and

[0040] FIG. 4 shows an exemplary compact robotic operating head for hand held use by the surgeon.

DETAILED DESCRIPTION

[0041] Reference is now made to FIG. 1 which illustrates an exemplary hand-held robotic system using the principle described hereinabove. The system described herewithin is a surgical system, illustrated here for shaping a bone, but it is to be understood that this is only one exemplary application of such a system and it can equally well be used for other applications where a hand guided operation is to be controlled to ensure that the operator does not deviate from predetermined bounds. Another such example is shown hereinbelow.

[0042] The robotic system includes a hand held robotic operating head 10, which is constructed of two parts. An upper part 11 is in the form of a gripping handle which is shaped so that it can be comfortably held in the hand 12 of the surgeon performing the operation. The surgeon uses a preoperative plan to decide in which pose (spatial position and angular orientation) to hold the head and which path to follow. Whereas in prior art surgical operating heads, the operating tool, whether a drill, a milling head, or any other surgical tool would be connected directly to the gripping handle, in this system, the tool 13 is connected to the gripping handle, and hence to the surgeon's hand, only through a controlled robot 14. The base 15 of the robot is attached to the gripping handle 11, while the operating tool 13 is held in the robotically controlled platform 16 of the robot. The robot can be of any type, and is illustrated in this disclosure as a Stewart-Gough parallel robot type, which has 6-extendible operating links between the base and the moveable platform. Such a robot is used to illustrate the implementation shown in the drawings and it clearly shows the operating action of the robot to correct the surgeon's deviation from the allowed path. However, it is to be understood that the robotic structure used can be of any suitable type, and in particular, a robot with actuating motors incorporated within the handle above the output platform may provide a more compact configuration. Compact dimensions are an important characteristic for such a hand-held application.

[0043] In FIG. 1, the operating head 10 is shown being used by the surgeon in a unicodyler knee replacement procedure, to mill the surface of a bone 18 with the operating tool 13, so that the milled bone head matches a preselected unicompartmental implant. Preoperatively the surgeon has planned the optimal location of the implant, and from this plan, the milled shape of the knee surface is calculated. This shape is input to the controller 8 as the preoperative plan which the surgeon has to adhere to accurately in order to ensure compliance with the planned operation, and hence a good fit of the implant on the bone.

[0044] A tracking system is used intra-operatively, to enable dynamic referencing of the bone 18 on which the operation is being performed with the robotic operating head 10. This is performed in order to link the locations of the bone and the robotic operating head 10 to the same coordinate system, so that movements of the robotic operating head can be correlated with the position of the bone. The tracking system may utilize a tracker 6 surveilling the operating site, and determining the pose of the robotic operating head 10 and of the subject's bone 18 by means of referencing targets 2, 4, attached to these items. If an optical tracking system is used, the referencing targets may conveniently be constructed of a plurality of light emitting diodes (LEDs) arranged in a predetermined pattern. The tracker 6 may then include optical sensors which are able to determine the pose of the referencing targets, such as by means of triangulation. Alternative configurations may include the use of retro-reflectors in the referencing targets 2, 4, in which case the tracker 6 would include both the light emitting sources (usually LED's) and the detectors for receiving the light retro-reflected from the referencing targets. Additionally, trackers are now available which operate in a completely passive mode, requiring no light emitting sources, and relying solely on high reflection coatings on the referencing targets, to reflect the ambient light to the tracker detector 6. The tracking system transfers the positional data relating to the robotic operating head and to the bone to the system controller 8, which also contains the preoperative plan data. Although the system has been described herewithin using optical tracking, it is to be understood that any other form of tracking may be equally well used, such as RF, sonic, ultrasonic or magnetic tracking or even a contact tracker like a digitizer.

[0045] As long as the surgeon manipulates the robotic operating head such that the surgical tool 13 follows the preoperative plan within an allowed deviation region, as ascertained by the tracker inputs to the system controller, the robot 14 remains locked and the entire robotic operating head 10 is manipulated as one rigid body. Once the surgeon deviates from the allowed path or pose, this deviation is detected by the tracked position of the referencing target 4 on the robotic operating head 10, and the controller is programmed to send a correction signal to the robot 14 to alter its pose, such that the tool tip 13 is brought back into the allowed region, even though the surgeon's hand has directed the robotic operating head 10 beyond those limits.

[0046] This situation is shown in FIG. 2, where it is seen that the surgeon's hand 12 has deviated, as shown by the axis 19 of the hand grip, from the angle which would maintain the axis 17 of the cutting tool 13 in the correct position and pose relative to the bone 18. However, this deviation has been sensed by the navigation 6 and control system 8, and the pose of the robot 14 has been changed in order to maintain the cutting tool 13 in the correct position and pose relative to the bone 18, despite the surgeon's hand deviation.

[0047] The robot 14 thus compensates for the surgeon's deviation and provides accurate compliance with the preoperative plan. In order to accomplish this successfully, the robot must react in real-time, which means that the system should have a response time sufficiently short that even with the most rapid movement the surgeon may make, the system will correct departure from the allowed preoperative plan before any damage is done. Typically, this means that the system should have a response bandwidth of the order of at least 10 Hz in order to follow the fastest human hand movements expected in such operations. Furthermore, the surgeon should not make movements much further from the allowed region that would cause the robot to exceed its working envelope. In general, both of these limitations should be achievable with the available robotic actuating motors and robotic control systems. The robotic actuators used can be of any type that can supply the required forces and the required speed, such that not only suitable electro-magnetic motors but also piezoelectric, hydraulic or pneumatic actuators may be used.

[0048] Furthermore some warning signal may be incorporated in the system, to advise the surgeon when his hand motion approaches the borders of the allowed region of operation according to the preoperative plan. Such a warning signal may be generated by the robot control, and could also be graduated, such as in intensity, tone or frequency, to indicate the extent of deviation of the surgeon from the preoperative plan. Possible implementations of this warning signal could be by an audible signal, or by a visual signal, or by some form of tactic feedback provided by the robot to the surgeon's hand.

[0049] Reference is now made to FIG. 3, which shows an additional exemplary application of the hand-held robot of FIG. 1, for performing a targeted procedure in a region 20 of soft tissue of a subject close to a sensitive anatomical structure, such as a nerve or a critical blood vessel 25. Contact with the sensitive anatomical structure could be damaging to the subject. Examples of such a procedure could be in tumor removal, biopsy performance, precise drug delivery, and others. The surgeon or physician can be warned of the presence of the hazardous feature either by an imaging system, such as a fluoroscopic system or by an ultrasonic imaging system, a probe of which 24 is shown in FIG. 3, or by means of a proximity sensor 29 attached to the needle 22 or surgical tool, which provides a warning signal when the sensor approaches the hazardous feature by a predetermined distance. Techniques such as Doppler ultrasound flow detection can be used to detect blood vessels by the flow of blood therein, and neuro-monitors can be used to detect the presence and position of nerve structures. The proximity sensor can advantageously deliver its warning signal by radio transmission to the control unit 8. Even for open surgical procedures, where the surgeon or physician could see the damage-sensitive feature, the robotically controlled system of this disclosure enables him to perform the desired procedure close to the damage-sensitive feature without fear that he will cause damage to the feature by a careless and unintentional movement of the hand.

[0050] Either the imaging system or the proximity sensor provides a signal input to the control system 8, which then provides a feedback to the robot 10 to prevent the needle 22 or surgical tool from approaching the sensitive feature, even if the surgeon or physician's hand movement would have directed it to do so. This is illustrated in FIG. 3, where, although the axis 26 of the handle would have directed the needle 22 straight at the blood vessel 25, the robotic control has changed the pose of the robot so as to divert the needle away from the blood vessel 25 and back to its intended target 20. This implementation differs from that shown in FIG. 2, in that the control system does not limit the operating head to operation within a predefined envelope, but rather prevents the operating head from getting too close to a forbidden region of operation. However, both implementations share the common feature that the robotic control uses a warning signal provided by a position detection system in order to prevent the operating head from operating in a region where the operator's hand movement would have directed it to do so.

[0051] The use of this robotic compensation system has the advantage over prior art free-hand manual proximity warning systems in that the accuracy of the procedure can be increased compared to that of prior art systems having no active control of the surgeon's hand position. It is possible to provide greater precision and thus to operate closer to hazardous locations than using manual proximity warning systems, and thus to achieve a better operational result.

[0052] Reference is now made to FIG. 4, which shows a schematic cut-away representation of a complete robotic operating head 30 with a robot of sufficiently compact design that it can be incorporated into the body profile of the head. The head thus becomes much more compact and readily handled by the surgeon than that shown schematically in FIGS. 1 to 3. A schematic outline of a robot is shown in dotted lines within the body of the head. The surgical tool 13, shown in the example of FIG. 4 with a milling bur on its working extremity may be rotated by means of a motor 38 mounted on the moving platform 32 of the robot, or by a shaft driven by a motor located remotely. If the tool is of the type that does not require motion, such as scalpel ablation, coagulation, laser cutting, or similar procedures, the need for providing motion to the tool is obviated. The moving platform 32 may be actuated by means of robotically actuating arms 34 which are affixed at the end remote from the driven platform to the robotic base, 36, which is fixed relative to the complete robotic operating head 30. As previously mentioned, any other suitable robot structure may equally well be used, with its base attached to the robotic operating head 30 and with its driven output element bearing the surgical tool.

[0053] For those implementations using a tracking system, the set-up described in FIG. 1 illustrates only one possible arrangement by which the mutual motion of the robotic operating head 10 and the bone 18 are correlated. As an alternative to, or in addition to the tracking target 4 mounted on the gripping part 11 of the robotic operating head 10, a tracking target 5 can be mounted on the robotic moving platform 16 of the robot 14, such that the actual position of the surgical tool 13 is tracked directly. Since the system controller 8 knows the pose of the robot 14 and hence the positional relation between the gripping portion 11 of the robotic operating head and the surgical tool 13, the use of both of these tracking targets 4, 5, provides a level of redundancy which may be used for increasing the safety of the system.

[0054] Since both the bone and the robotic operating head are situated very close to each other, it may be disadvantageous to use a conventional external navigating or tracking system, which is generally disposed above the operating table and at some distance from the operating site, with its concomitant problems of accuracy at such a distance, and of the need to maintain a clear line of sight between the tracker and the tracking targets. According to an alternative implementation of the present system, the tracking could advantageously be performed locally, such as by mounting the tracker on the bone 18 and the tracking target or targets on the robotic operating head, either on the gripper part 11 or on the robotically directed tool holder platform 16, or on both, or vice versa with the tracker on the robotic operating head (whether the gripper part 11 or the moveable platform 16, or on both) and a tracking target on the bone 18.

[0055] It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.