BACKGROUND
This invention relates to a surgical robot calibration device. 5
Figure 1 shows a surgical robotic system 100 performing a minimally invasive procedure on a patient 102. The patient 102 is positioned on an operating table 103. In Figure 1, the procedure is being performed through a natural orifice of the patient 102. The natural orifice is the patent’s mouth. A minimally invasive procedure 10 performed through the mouth is typically termed a transoral surgery, and is often performed, for example, to remove tumours from the throat.
The surgical robot 100 comprises a robotic arm 101. The robotic arm 101 comprises a plurality of joints 104 by which the configuration of that robotic arm can be altered. 15 The robotic arm 101 comprises an attachment for a surgical instrument 106 at its distal end. The surgical instrument has an end effector at its distal end for performing aspects of the minimally invasive procedure. The surgical instrument could, for example, be a cutting or grasping device, or an imaging device (such as an endoscope). 20
The configuration of the robotic arm 101 may be remotely controlled in response to inputs received at a remote surgeon console 120. A surgeon may provide inputs to the remote console 120. The remote surgeon console comprises one or more surgeon input devices. For example, these may take the form of a hand controller and/or foot 25 pedal.
A control system 124 connects the surgeon console 120 to the surgical robotic arm 101. The control system receives inputs from the surgeon input device(s) and converts these to control signals to move the joints 104 of the robotic arm and the surgical 30 instrument 106. The control system 124 sends these control signals to the robot, where the corresponding joints are driven accordingly. In order for the control system to control the surgical robotic arm correctly and safely, the surgical robot must be calibrated.
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SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a surgical robot calibration device for calibrating a surgical robotic system to perform a minimally invasive 5 procedure through a natural orifice, the surgical robotic system comprising a surgical robotic arm and a surgical instrument having a rigid linear shaft, the surgical robot calibration device comprising a resistive spacer configurable to hold a calibration port in a fixed position spaced from the natural orifice, such that when the calibration port is held in the resistive spacer, the surgical instrument is insertable into the natural 10 orifice via the calibration port.
The resistive spacer may be configured to be received at one end in the natural orifice, and comprise an aperture at an opposing end for receiving the calibration port.
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The resistive spacer may be configured to be received at one end in the natural orifice and comprise a surface spaced from that end having one or more apertures each configured to receive a calibration port.
The resistive spacer may be configured to be received at one end in the natural orifice 20 and comprise a surface spaced from that end that is pierceable so as to receive a calibration port.
The resistive spacer may be curved so as to define a substantially domed three-dimensional shape. 25
The resistive spacer may be configured to bridge the natural orifice.
The resistive spacer may comprise a calibration port attachment that is movably mounted with respect to the resistive spacer. 30
The moveably mounted calibration port attachment may be mounted on one or more moveable rails such that, when the resistive spacer is bridging the natural orifice, the calibration port attachment is moveable in a plane above the natural orifice.
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The calibration port attachment may be securable in position relative to the resistive spacer such that, in use, the calibration port is held in the fixed position.
The resistive spacer may comprise a surface having one or more apertures each 5 configured to receive a calibration port.
The resistive spacer may comprise a surface that is pierceable so as to receive a calibration port.
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The natural orifice may be a patient’s mouth and the resistive spacer may be configured to bridge the patient’s head so as to bridge the mouth.
The resistive spacer may extend from a base at its proximal end, comprise a plurality of joints by which the configuration of that resistive spacer can be altered and comprise 15 an attachment for the calibration port at its distal end.
According to a second aspect of the invention there is provided a surgical robot calibration device for calibrating a surgical robotic system to perform a minimally invasive procedure through a natural orifice, the surgical robotic system comprising a 20 surgical robotic arm and a surgical instrument having a rigid linear shaft, the surgical robot calibration device comprising a resistive spacer having formed integrally therewith a calibration port, the resistive spacer being configured to retain the calibration port at a fixed position spaced from the natural orifice, such that the surgical instrument is insertable into the natural orifice via the calibration port. 25
The resistive spacer may be configured to be received at one end in the natural orifice, and the calibration port may be formed integral therewith at an opposing end.
The resistive spacer may be configured to be received at one end in the natural 30 orifice and comprise a surface spaced from that end having one or more calibration ports formed integral therewith.
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The resistive spacer may be curved so as to define a substantially domed three-dimensional shape.
The resistive spacer may be configured to bridge the natural orifice.
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The calibration port may be movable with respect to the resistive spacer.
The calibration port may be formed integrally with a moveable rail such that, when the resistive spacer is bridging the natural orifice, the calibration port is moveable in a plane above the natural orifice. 10
The calibration port may be securable in position relative to the resistive spacer such that, in use, the calibration port is held in the fixed position.
The resistive spacer may comprise a surface having one or more calibration ports 15 formed integrally therewith.
The natural orifice may be a patient’s mouth and the resistive spacer may be configured to bridge the patient’s head so as to bridge the mouth.
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The resistive spacer may extend from a base at its proximal end, comprise a plurality of joints by which the configuration of that resistive spacer can be altered and have the calibration port formed integrally therewith at its distal end.
The natural orifice may be a mouth and the resistive spacer may comprise an 25 attachment for a mouth retractor.
The mouth retractor may be detachable from the attachment.
The resistive spacer may be elastically deformable, and the attachment may comprise 30 a lip, such that: with the resistive spacer in a first configuration, the lip attaches the mouth retractor to the resistive spacer; and with the resistive spacer in a second, deformed, configuration, the mouth retractor can pass over the lip in order to detach the mouth retractor from the resistive spacer.
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The resistive spacer may be capable of resisting external forces applied to the calibration port by the surgical instrument such that, in use, the calibration port is maintained in the fixed position.
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The resistive spacer may be capable of resisting external forces of at least 2 Newtons applied to the calibration port by the surgical instrument.
According to a third aspect of the invention there is provided a method of calibrating a surgical robotic system to perform an invasive procedure via a natural orifice using the 10 surgical robot calibration device as claimed in any preceding claim, the surgical robotic system comprising a surgical robotic arm having a series of joints by which the configuration of the robotic arm can be altered, the series of joints extending from a base at a proximal end of the surgical robotic arm to a surgical instrument having a rigid linear shaft attached at a distal end of the surgical robotic arm, and the method 15 comprising determining a fulcrum about which the surgical instrument pivots when the configuration of the robotic arm is altered whilst the surgical instrument is inserted into the calibration port.
BRIEF DESCRIPTION OF THE DRAWINGS 20
The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:
Figure 1 shows a surgical robotic system. 25
Figure 2 shows an example of a surgical robotic arm.
Figure 3 is a flow diagram showing the steps of a surgical robot calibration process.
Figure 4a shows a first example surgical robot calibration device.
Figure 4b shows a second example surgical robot calibration device.
Figure 4c shows a third example surgical robot calibration device. 30
Figure 4d shows the first example surgical robot calibration device.
Figure 4e shows a fourth example surgical robot calibration device.
Figure 4f shows a fifth example surgical robot calibration device.
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Figures 5a, 5b and 5c show an example resistive spacer comprising an attachment for a detachable mouth retractor.
Figure 6a shows a sixth example surgical robot calibration device.
Figure 6b shows a seventh example surgical robot calibration device.
Figure 7 shows a eighth example surgical robot calibration device. 5
DETAILED DESCRIPTION OF THE DRAWINGS
The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application. 10 Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.
The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, 15 the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
Surgical robotic arm 20
Figure 2 shows an example of a robotic arm 201. The robotic arm 201 may be comprised within a surgical robotic system, such as the surgical robotic system shown in Figure 1. Although the surgical robotic system shown in Figure 1 comprises one surgical robotic arm, it is to be understood that a surgical robotic system may comprise 25 a plurality of surgical robotic arms.
The robotic arm 201 comprises a base 209. The robotic arm has a series of rigid arm members. Each arm member in the series is joined to the preceding arm member by a respective joint 204a-g. Joints 204a-e and 204g are revolute joints. Joint 204f is 30 composed of two revolute joints whose axes are orthogonal to each other, as in a Hooke’s or universal joint. Joint 204f may be termed a “wrist joint”. A robotic arm could be jointed differently from the robotic arm of Figure 2. For example, joint 204d could be omitted and/or joint 204f could permit rotation about a single axis. The robotic arm
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could include one or more joints that permit motion other than rotation between respective sides of the joint, such as a prismatic joint by which an instrument attachment can slide linearly with respect to more proximal parts of the robotic arm.
The joints are configured such that the configuration of the robotic arm can be altered 5 allowing the distal end 230 of the robotic arm to be moved to an arbitrary point in a three-dimensional working volume illustrated generally at 235. One way to achieve that is for the joints to have the arrangement illustrated in Figure 2. Other combinations and configurations of joints could achieve a similar range of motion, at least within the zone 235. There could be more or fewer arm members. 10
The robotic arm 201 comprises a series of motors 210a-h. With the exception of the compound joint 204f, which is served by two motors, each motor is arranged to drive rotation about a respective joint of the robotic arm. The motors are controlled by a control system (such as control system 124 shown in Figure 1). The control unit 15 comprises a processor and a memory. The memory stores, in a non-transient way, software code that can be executed by the processor to cause the processor to control the motors 210a-h in the manner described herein.
The robotic arm 201 may comprise a series of sensors 207a-h and 208a-h. These 20 sensors may comprise, for each joint, a position sensor 207a-h for sensing the rotational position of the joint and a force sensor 208a-h for sensing forces (such as torque) applied about the joint’s rotation axis. Compound joint 204f may have two pairs of sensors. One or both of the position and force sensors for a joint may be integrated with the motor for that joint. The outputs of the sensors are passed to the control 25 system where they form inputs for the processor.
The distal end of the robotic arm 230 has an attachment 216 by means of which a surgical instrument 206 can be releasably attached. The surgical instrument has a rigid linear shaft 261. The surgical instrument has an end effector 262 at the distal end 30 of the shaft. The end effector 262 consists of a device for engaging in a procedure, for example a cutting, grasping or imaging device. As described herein, terminal joint 204g may be a revolute joint. The surgical instrument 206 and/or the attachment 216 may be configured so that the instrument extends linearly parallel with the rotation axis
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of the terminal joint 204g of the robotic arm. In this example the instrument extends along an axis coincident with the rotation axis of joint 204g.
Joints 204e and 204f of the robotic arm are configured so that with the distal end of the robotic arm 230 held at an arbitrary location in the working volume 235 the surgical 5 instrument 206 can be directed in an arbitrary direction within a cone. Such a cone is illustrated generally at 236. One way to achieve that is for the terminal part of the arm to comprise the pair of joints 204e and 204f whose axes are mutually arranged as described above. Other mechanisms can achieve a similar result. For example, joint 204g could influence the attitude of the instrument if the instrument extends in a 10 direction which is not parallel to the axis of joint 204g.
For some types of minimally invasive procedure, the surgical instrument 206 may be inserted into the patient’s body through a synthetic port 217. For example, the minimally invasive procedure may be performed within the patient’s abdomen. The 15 port 217 may comprise a passageway 217a. The passageway 217a may pass through the outer tissues 202 of the patient so as to limit disruption to those tissues as the surgical instrument is inserted and removed, and as the instrument is manipulated within the patient’s body. The port 217 may comprise a collar 217b. The collar 217b may prevent the port 217 being inserted too far through the outer tissues 202 of the 20 patient.
For other types of minimally invasive procedure, the surgical instrument may be inserted directly into the patient’s body through a natural orifice. For example, the minimally invasive procedure may be performed in the patient’s throat, and the natural 25 orifice may be the patient’s mouth (e.g. as shown in Figure 1).
Calibration process
The surgical robot is calibrated prior to performing a minimally invasive procedure. 30 During calibration, the control system (e.g. such as control system 124 shown in Figure 1) of the robotic arm 201 determines the fulcrum about which the surgical instrument pivots when the configuration of the robotic arm is altered whilst the surgical instrument is inserted into the port or the natural orifice. The control system determines said
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fulcrum by means of a calibration process that is performed whilst the surgical instrument 206 is inside the port or natural orifice. Figure 3 is a flow diagram showing the steps of such a calibration process.
Whilst the surgical instrument is inside the port or natural orifice, the configuration of 5 the robotic arm is altered 301. The configuration of the robotic arm 301 is altered by the application of external forces directly onto the robotic arm. For example, a member of the bedside team (e.g. an operating room nurse) may apply forces directly to the robotic arm (e.g. by pushing a joint of the robotic arm). During calibration, the control system (such as control system 124 shown in Figure 1) controls the robotic arm to 10 maintain a position in which it is placed by means of external forces applied directly to the robotic arm.

CLAIMS
1. A surgical robot calibration device configured to be used when calibrating a surgical robotic system to perform a minimally invasive procedure through a natural orifice, the surgical robotic system comprising a surgical robotic arm and a surgical 5 instrument having a rigid linear shaft, the surgical robot calibration device comprising a resistive spacer configurable to hold a calibration port in a fixed position spaced from the natural orifice, such that when the calibration port is held in the resistive spacer, the surgical instrument is insertable into the natural orifice via the calibration port to enable a fulcrum about which the surgical instrument pivots whilst the surgical 10 instrument is inserted into the calibration port to be determined.
2. A surgical robot calibration device as claimed in claim 1, wherein the natural orifice is a mouth.
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3. A surgical robot calibration device as claimed in claim 1 or 2, wherein the resistive spacer is configured to be received at one end in the natural orifice, and comprises an aperture at an opposing end for receiving the calibration port.
4. A surgical robot calibration device as claimed in any of claims 1to 3, wherein 20 the resistive spacer is configured to be received at one end in the natural orifice and comprises a surface spaced from that end having one or more apertures each configured to receive a calibration port.
5. A surgical robot calibration device as claimed in any preceding claim , wherein 25 the resistive spacer is configured to be received at one end in the natural orifice and comprises a surface spaced from that end that is pierceable so as to receive a calibration port.
6. A surgical robot calibration device as claimed in claim 4 or 5, wherein the 30 resistive spacer is curved so as to define a substantially domed three-dimensional shape.
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7. A surgical robot calibration device as claimed in claim 1 or 2, wherein the resistive spacer is configured to bridge the natural orifice.
8. A surgical robot calibration device as claimed in claim 7, wherein the resistive spacer comprises a calibration port attachment that is movably mounted with respect 5 to the resistive spacer.
9. A surgical robot calibration device as claimed in claim 8, wherein the moveably mounted calibration port attachment is mounted on one or more moveable rails such that, when the resistive spacer is bridging the natural orifice, the calibration port 10 attachment is moveable in a plane above the natural orifice.
10. A surgical robot calibration device as claimed in claims 8 or 9, wherein the calibration port attachment is securable in position relative to the resistive spacer such that, in use, the calibration port is held in the fixed position. 15
11. A surgical robot calibration device as claimed in claim 7, wherein the resistive spacer comprises a surface having one or more apertures each configured to receive a calibration port.
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12. A surgical robot calibration device as claimed in claim 7, wherein the resistive spacer comprises a surface that is pierceable so as to receive a calibration port.
13. A surgical robot calibration device as claimed in any of claims 7 to 12, wherein the natural orifice is a patient’s mouth and the resistive spacer is configured to bridge 25 the patient’s head so as to bridge the mouth.
14. A surgical robot calibration device as claimed in claim 1 or 2, wherein the resistive spacer extends from a base at its proximal end, comprises a plurality of joints by which the configuration of that resistive spacer can be altered and comprises an 30 attachment for the calibration port at its distal end.
15. A surgical robot calibration device configured to be used when calibrating a surgical robotic system to perform a minimally invasive procedure through a natural
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orifice, the surgical robotic system comprising a surgical robotic arm and a surgical instrument having a rigid linear shaft, the surgical robot calibration device comprising a resistive spacer having formed integrally therewith a calibration port, the resistive spacer being configured to retain the calibration port at a fixed position spaced from the natural orifice, such that the surgical instrument is insertable into the natural orifice 5 via the calibration port to enable a fulcrum about which the surgical instrument pivots whilst the surgical instrument is inserted into the calibration port to be determined.
16. A surgical robot calibration device as claimed in claim 15, wherein the natural orifice is a mouth. 10
17. A surgical robot calibration device as claimed in claim 15 or 16, wherein the resistive spacer is configured to be received at one end in the natural orifice, and the calibration port is formed integral therewith at an opposing end.
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18. A surgical robot calibration device as claimed in any of claims 15 to 17, wherein the resistive spacer is configured to be received at one end in the natural orifice and comprises a surface spaced from that end having one or more calibration ports formed integral therewith.
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19. A surgical robot calibration device as claimed in claim 18, wherein the resistive spacer is curved so as to define a substantially domed three-dimensional shape.
20. A surgical robot calibration device as claimed in claim 15 or 16, wherein the resistive spacer is configured to bridge the natural orifice. 25
21. A surgical robot calibration device as claimed in claim 20, wherein the calibration port is movable with respect to the resistive spacer.
22. A surgical robot calibration device as claimed in claim 21, wherein the 30 calibration port is formed integrally with a moveable rail such that, when the resistive spacer is bridging the natural orifice, the calibration port is moveable in a plane above the natural orifice.
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23. A surgical robot calibration device as claimed in claim 21 or 22, wherein the calibration port is securable in position relative to the resistive spacer such that, in use, the calibration port is held in the fixed position.
24. A surgical robot calibration device as claimed in claim 20, wherein the resistive 5 spacer comprises a surface having one or more calibration ports formed integrally therewith.
25. A surgical robot calibration device as claimed in any of claims 20 to 24, wherein the natural orifice is a patient’s mouth and the resistive spacer is configured to bridge 10 the patient’s head so as to bridge the mouth.
26. A surgical robot calibration device as claimed in claim 15 or 16, wherein the resistive spacer extends from a base at its proximal end, comprises a plurality of joints by which the configuration of that resistive spacer can be altered and has the 15 calibration port formed integrally therewith at its distal end.
27. A surgical robot calibration device as claimed in any of claims 1 to 6 or 15 to 19, wherein the natural orifice is a mouth and the resistive spacer comprises an attachment for a mouth retractor. 20
28. A surgical robot calibration device as claimed in claim 27, wherein the mouth retractor is detachable from the attachment.
29. A surgical robot calibration device as claimed in claim 28, wherein the resistive 25 spacer is elastically deformable, and the attachment comprises a lip, such that:
with the resistive spacer in a first configuration, the lip attaches the mouth retractor to the resistive spacer; and
with the resistive spacer in a second, deformed, configuration, the mouth retractor can pass over the lip in order to detach the mouth retractor from the resistive 30 spacer.
30. A surgical robot calibration device as claimed in any preceding claim, wherein the resistive spacer is capable of resisting external forces applied to the calibration
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port by the surgical instrument such that, in use, the calibration port is maintained in the fixed position.
31. A surgical robot calibration device as claimed in claim 30, wherein the resistive spacer is capable of resisting external forces of at least 2 Newtons applied to the 5 calibration port by the surgical instrument.
32. A method of calibrating a surgical robotic system to perform an invasive procedure via a natural orifice using the surgical robot calibration device as claimed in any preceding claim, the surgical robotic system comprising a surgical robotic arm 10 having a series of joints by which the configuration of the robotic arm can be altered, the series of joints extending from a base at a proximal end of the surgical robotic arm to a surgical instrument having a rigid linear shaft attached at a distal end of the surgical robotic arm, and the method comprising determining a fulcrum about which the surgical instrument pivots when the configuration of the robotic arm is altered whilst 15 the surgical instrument is inserted into the calibration port.