Apparatus and method for assisting tool use

Abstract

Apparatus and related methods for assisting tool use includes one or more motors, a wrist support and a shaft coupled to the one or more motors. The shaft includes a coupling to couple to a tool to enable a user resting a hand with the wrist on the wrist support to hold and manipulate the tool with one or more fingers. The apparatus can include a controller configured to: receive position data indicative of a position of an active end of the tool; receive constraint data indicative of one or more regions of space in which the active end should not be positioned; and process the position and constraint data to control the one or more motors to bias the active end out of a region indicated by the constraint data when a position indicated by the position data is within the region indicated by the constraint data.

Claims

1. Apparatus for assisting tool use, the apparatus comprising: one or more motors; a wrist support; a shaft coupled to the one or more motors at a first end of the shaft; a coupling disposed on the shaft at a second end of the shaft and configured to accept a tool to enable a user resting a hand with the wrist on the wrist support to hold and manipulate the tool with one or more fingers of the hand; and a controller configured to: receive position data indicative of a position of an active end of a tool coupled to the coupling; receive constraint data indicative of one or more regions of space in which the active end of the tool should not be positioned; and process the position and constraint data to control the one or more motors to bias the active end of the tool out of the region when a position indicated by the position data is within a region indicated by the constraint data wherein the one or more motors, wrist support and shaft coupling define an integrated apparatus.

2. Apparatus according to claim 1, wherein the shaft has at least one linear and at least one rotational degree of freedom.

3. Apparatus according to claim 2, wherein the at least one linear degree of freedom comprises a degree of freedom along a direction towards and away from the wrist support.

4. Apparatus according to claim 1, wherein the tool accepted by the coupling comprises a surgical tool.

5. Apparatus according to claim 1, wherein the constraint and position data are in a coordinate system registered to an object to be worked on with the tool.

6. Apparatus according to claim 1, wherein the one or more motors are back driveable, thereby enabling a user to move a tool attached to the coupling without energising the one or more motors.

7. Apparatus according to claim 1, wherein the one or more regions are configured to constrain a range of movement of the active end and wherein a largest distance between two positions of the active end within the range of movement is less than 10 cm, optionally less than 5 cm, 4 cm or 3 cm.

8. Apparatus according to claim 1, wherein the apparatus is configured to mechanically constrain a range of movement of the coupling and wherein a largest distance between two positions of the coupling within the range of movement is less than 10 cm, optionally less than 5 cm, 4 cm or 3 cm.

9. Apparatus according to claim 1, wherein the one or more motors are disposed in a housing and the wrist support is secured in relation to or is part of the housing.

10. Apparatus according to claim 1 comprising one or more position encoders, wherein each of the one or more motors is associated with a position encoder from which a configuration of the shaft along a corresponding degree of freedom can be determined and wherein receiving position data comprises: receiving encoder data from the one or more position encoders; receiving calibration data indicative of a relationship between data from the one or more position encoders and the active end of the tool; and using the encoder and calibration data to obtain the position data.

11. Apparatus according to claim 1, wherein the tool accepted by the coupling comprises one or more of a cutting tool, a drilling tool, a burring tool, a heating tool and a measuring tool.

12. Apparatus according to claim 5, wherein the object is part of a patient.

13. Apparatus according to claim 1, wherein the apparatus is configured as a surgical robot.

14. Apparatus according to claim 1, wherein the controller is configured to: process the position and constraint data to cause generation of a control signal for the tool to deactivate the active end when a position indicated by the position data is within a region indicated by the constraint data.

15. Apparatus for assisting tool use, the apparatus comprising: one or more motors disposed in a housing; a wrist support on the housing; a shaft extending through the housing, the shaft coupled to the one or more motors at a first end of the shaft; a coupling disposed on the shaft at a second end of the shaft and configured to accept a tool to enable a user resting a hand with the wrist on the wrist support to hold and manipulate the tool with one or more fingers of the hand; and a controller configured to: receive position data indicative of a position of an active end of a tool coupled to the coupling; receive constraint data indicative of one or more regions of space in which the active end of the tool should not be positioned; and process the position and constraint data to control the one or more motors to bias the active end of the tool out of the region when a position indicated by the position data is within a region indicated by the constraint data.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) A specific embodiment is now described by way of example to illustrate the described aspects and embodiments, with reference to the accompanying drawings, in which:

(2) FIGS. 1 to 3 illustrate a device to assist tool use;

(3) FIG. 4 illustrates a view of the device with part of its housing removed;

(4) FIG. 5 illustrates a controller for the device; and

(5) FIG. 6 illustrates a method of using the device.

DETAILED DESCRIPTION

(6) With reference to FIGS. 1 to 3, a device 2 for assisting manipulations of a tool 4 by a user using his or her hand 6 comprises a housing 8. A wrist support 10 is provided on a surface 12 of the housing 8, which, in use, is on top of the device 2. The wrist support may comprise a pad of resilient foam material, for example memory foam, to comfortably support the wrist. The tool 4 has body 14 and an active end 16, for example configured as a burr. In some embodiments, the tool is a measurement tool that can be used to gather data from a workpiece or patient, for example the size of a bone or joint. The device 2 comprises a shaft 18 extending through a slot 20 in the surface 12 of the housing 8. The shaft 18 forms a coupling 22 at one end, for engaging the body 14 of the tool 4. For example, in some embodiments the coupling 22 is configured as a ring for accepting the body 14 and comprises one or more set screws (not shown) to secure the body 14 inside the coupling 22. Of course various other embodiments of the coupling 22 to secure the body 14 will be apparent to a person skilled in the art.

(7) The slot 20 is elongate in a direction generally along the forearm when a user rests a hand on the wrist support 10, to allow movement fore and aft of the shaft 18 by, respectively, extension and flexion of fingers of the user's hand holding the body 14 of the tool 4. The slot 20 also has extent perpendicular to the fore/aft direction to enable side to side movement of the shaft 18, as described in detail below. In some embodiments, the slot mechanically limits a range of motion of the shaft. The shaft 18 is inclined in a direction aft to fore, rising in a forwards direction away from the wrist support 10, to accommodate the slope of the user's palm when resting the wrist on the wrist support 10, in particular in an aft position when the fingers are flexed.

(8) The housing 8 comprises a weighted base or a clamping arrangement (not shown) to dispose the housing in a substantially fixed position relative to the object to be worked on, during operation. The device 2 may also comprise a mechanically or motorised moveable positioning arrangement to aid positioning of the device 2.

(9) With reference to FIG. 4, the shaft 18 is coupled to three motors to control three corresponding degrees of freedom of the shaft 18: yaw, pitch and aft/fore movement, as illustrated in FIG. 4. A first motor arrangement 24 is secured to a base 26 of the housing 8 and controls yaw motion and torques. The output of the first motor arrangement 24 is connected to a platform 28 carrying a second motor arrangement 30, which controls pitch motion and torques. An output of the second motor arrangement 30 is secured to a platform 32 carrying a third motor arrangement 34, which controls fore and aft motion and forces. An output of the motor arrangement 34 is coupled to the shaft 18. The motor arrangements 24, 30, 34 comprise an electric motor and a low friction gearbox transmitting the torque of the electric motor to the output. In the case of the third motor arrangement 34, the gearbox comprises a worm gear or recirculating ball screw, for example, to transform the torque output to a linear motion/force output in the fore and aft direction. Of course other arrangements to generate the linear output may be used in other embodiments, including a linear motor.

(10) The motor arrangements 24, 30, 34 are sufficiently low-friction to be back-driveable by a user exerting a force or torque on the tool 4 and hence the coupling 22, so that the user can manipulate the tool without forces or torques having to be generated by the electric motors. To this end, the force required at the coupling to overcome the back drive resistance of the motor arrangements 24, 30, 34 is less than 0.4N, preferably less than 0.3N, 0.2N, 0.1N or 0.05N. The axes of rotation of the motor arrangements 24 and 30 intersect in a point aligned (subject to tolerances) with the linear axis of translation of the motor arrangement 34, in some embodiments.

(11) With reference to FIG. 5, a controller 36 for the motor arrangements 24, 30, 34 comprises a position module 36. The position module 36 is configured to receive position data and to derive data indicative of the position of the active end 16 of the tool 4. The position data is, in some embodiments, received from encoders associated with the motor arrangements 24, 30, 34 and a position of the active end 16 is derived from this data based on knowledge of the configuration of the device 2 and tool 4, possibly after a calibration routine, if required, as is well known to a person skilled in the art. In some embodiments optical markers on the tool 4 and/or shaft 18 are detected in space using an optical detection system to measure the position and orientation of the tool 4 in place of the use of encoders.

(12) A constraint module 40 defines one or more regions of space into which the active end 16 of the tool 4 should not enter, in some embodiments taking a model of an object to be worked on and a user input defining one or more regions as an input.

(13) A registration module 42 contains information regarding the relative position and orientation of the device 2 and object to be worked on so that the position and constraint data can be defined in or transformed into a common coordinate system. The information may be derived using calibration during a set-up procedure, for example using a calibration tool of known configuration to acquire points on the object in device coordinates, as is well known to the person skilled in the art. For example, in case of the device being used in a surgical procedure, the points on the object may be anatomical landmarks that can be used for registration with a model of an anatomical region to be worked on with the tool 4.

(14) A process module 44 is configured to combine information indicative of the position of the active end 16 and information indicative of the one or more regions to generate forces/torques biasing the tool 4 so that the active end 16 is moved out of the one or more regions into a region where presence of the active end 16 is undesirable, that is providing active constraints or a “virtual wall” to guide tool use. In some embodiments, the process module further or instead deactivates the active end if the active end enters one of the one or more regions. In the latter case, motors may not be required and the device may omit the motors (but retain the encoders, where applicable).

(15) In some specific embodiments, active constraints, including the generation and definition of the one or more regions, are implemented using the techniques disclosed in any one or more of S. A. Bowyer, B. L. Davies, F. Rodriguez y Baena, IEEE Transactions on Robotics, Vol. 30, No. 1, page 138, February 2014; WO2002/060653; WO2003/043515; S. C. Ho, R. D. Hibberd and B. L. Davies, IEEE Engineering in Medicine and Biology, May/June 1995, page 292; all incorporated herein by reference. Registration techniques used in some embodiments are described in WO2003/04515 and/or WO2006/048651, both incorporated by reference herein, are used. In some embodiments, planning of the tool use using simulation as disclosed in WO2002/061688, incorporated herein by reference, is employed.

(16) With reference to FIG. 6, a method of operating the device 2 is now described in the context of surgery. However, it will be apparent that this disclosure equally applies to tool use on objects other than body parts of a patient.

(17) At step 46, the object to be worked on, typically a body part of a patient in the case of surgery, is located relative to the device 2. The body part may be clamped in place, as is well known. The patient may be placed on a motorised bed that is moved relative to the device 2, or in some embodiments the device 2 may simply be placed next to the patient and held in place by friction or by a clamping arrangement. If not already present, a tool 4 is coupled to the device 2. These preparations may, for example, be carried out by a theatre nurse. At step 48, the frame of reference/coordinate system of the device 2 is registered with the object, as is well known and briefly described above, and constraint regions are loaded into the controller 36.

(18) At step 50, the surgeon performs the surgery by placing a wrist on the wrist support 10 and manipulating the tool 4 with two or more fingers (or with one finger in a stall or sleeve fixed to the tool, to modify, for example cut or ablate, tissue as required by the surgery. While the surgeon performs the surgery, the position of the active end 16 of the tool is obtained, for example as described above, and the constraints are applied to urge the active end of the tool to remain in a desired region for the surgery and avoid injury to surrounding tissue. Position is obtained and constraints are applied as long as the surgeon performs the procedure with the tool 4.

(19) The various methods executed by or in relation to the device 2 described above may be implemented by a computer program. The computer program may include computer code arranged to instruct a computer to perform the functions of one or more of the various methods described above. The computer program and/or the code for performing such methods may be provided to an apparatus, such as a computer, on one or more computer readable media or, more generally, a computer program product. The computer readable media may be transitory or non-transitory. The one or more computer readable media could be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, or a propagation medium for data transmission, for example for downloading the code over the Internet. Alternatively, the one or more computer readable media could take the form of one or more physical computer readable media such as semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disc, and an optical disk, such as a CD-ROM, CD-R/W or DVD.

(20) In an implementation, the modules, components and other features described herein can be implemented as discrete components or integrated in the functionality of hardware components such as ASICS, FPGAs, DSPs or similar devices.

(21) A “hardware component” is a tangible (e.g., non-transitory) physical component (e.g., a set of one or more processors) capable of performing certain operations and may be configured or arranged in a certain physical manner. A hardware component may include dedicated circuitry or logic that is permanently configured to perform certain operations. A hardware component may be or include a special-purpose processor, such as a field programmable gate array (FPGA) or an ASIC. A hardware component may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations.

(22) Accordingly, the phrase “hardware component” should be understood to encompass a tangible entity that may be physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein.

(23) In addition, the modules and components can be implemented as firmware or functional circuitry within hardware devices. Further, the modules and components can be implemented in any combination of hardware devices and software components, or only in software (e.g., code stored or otherwise embodied in a machine-readable medium or in a transmission medium).

(24) A computing device implementing the disclosed methods may be integrated within the housing 8 or the disclosed apparatus may include the computing device as a separate component or separate distributed components. The computing device may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The computing device may be a personal computer (PC), a tablet computer, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single computing device has been referenced, the term “computing device” shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein.

(25) Unless specifically stated otherwise, as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as ‘processing’, ‘receiving’, ‘deriving’, ‘combining’ or the like, refer to the actions and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

(26) It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific example implementations, it will be recognized that the disclosure is not limited to the implementations described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.