Controlling a robotic system actuator for driving an elongate flexible medical instrument

Abstract

This method (200) is intended for controlling an actuator connected kinematically to a drive member capable of coming into contact with an elongate flexible medical instrument so as to control the movement of said drive member along an axis. It comprises measuring (206) a force exerted by the medical instrument on the drive member along the axis, transmitting (214) to the actuator a primary control signal suitable for causing a speed of movement of the drive member along the axis to converge towards a predetermined speed setpoint as long as the measured force is below a predetermined threshold, and transmitting (216) to the actuator a secondary control signal suitable for causing the measured force to converge towards a predetermined force setpoint when the measured force exceeds said threshold.

Description

[0001] DESCRIPTION

[0002] CONTROL OF A ROBOTIC SYSTEM ACTUATOR FOR DRIVING AN ELONGATED FLEXIBLE MEDICAL INSTRUMENT

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to robotic systems for driving elongated flexible medical instruments such as guides, catheters, etc. used in particular in angioplasty procedures. It relates more particularly to the control of the actuators of such a robotic system.

[0005] TECHNOLOGICAL BACKGROUND

[0006] Angioplasty, which involves manually inserting an elongated, flexible medical instrument such as a catheter or guidewire into a patient, is a relatively standard medical procedure. However, since this procedure is monitored by X-ray angiography, the practitioner performing this procedure is exposed to significant radiation if performing such an operation on many patients.

[0007] In order to reduce the risks for the practitioner, it has been proposed to robotize such an insertion by means of robotic systems comprising clamping members, moved by actuators, which can move towards and away from each other to respectively grip or release said medical instrument, said clamping members, once brought together so as to grip the medical instrument, can perform: a synchronous longitudinal translation to move the medical instrument forward or backward, and / or opposite transverse translations to rotate the medical instrument around its axis of elongation.

[0008] Such a robot is known for example from FR 3 044 541.

[0009] The clamping force applied by the clamping members of these robotic systems must satisfy two opposing constraints. On the one hand, it must be sufficient to allow the medical instrument to be driven without slipping. On the other hand, it must not be too high to avoid ovalization of the medical instrument, i.e. a modification of the cross-section of said medical instrument which, from circular in the new state, would become oval or elliptical under the effect of the clamping force. Such ovalization is indeed troublesome when driving the medical instrument in rotation because it can oppose correct rotation of the medical instrument, as described in WO 2022 / 219165.

[0010] Generally, to move the clamping members from their spaced apart position to their close position, the actuators are controlled by means of a control law aimed at moving the members to a predetermined position, depending on the type of medical instrument being handled, which must have been previously entered by the robot operator. The clamping members are then held in this position as long as they are in a phase during which they must grip the medical instrument. However, this often leads to ovalization of the medical instrument.

[0011] To solve this problem, WO 2022 / 219165 proposed equipping these robotic systems with sensors that measure the clamping force and a regulator that maintains the clamping force between a minimum and a maximum threshold. Thus, when the actuators are in a close position, their clamping force is regulated.

[0012] However, this solution is not entirely satisfactory. Indeed, WO 2022 / 219165 does not detail how this control of the clamping force of the clamping members is linked to the control of the movement of the clamping members from their spaced apart position to their close position. However, the inventors realized that it was difficult to control this movement of the clamping members in such a way as to reconcile compliance with the maximum clamping force threshold and speed of movement of the clamping members.

[0013] STATEMENT OF THE INVENTION

[0014] An objective of the invention is to enable rapid movement, in a direction of movement, of a drive member intended to come into contact with an elongate flexible medical instrument while preventing the force exerted by the drive member on the elongate flexible medical instrument in the direction of movement from exceeding a predetermined threshold. Other objectives are to prevent damage to the medical instrument and to enable slip-free driving of the medical instrument by the drive member.

[0015] To this end, the invention relates, according to a first aspect, to a method for controlling a robotic system for driving, in translation and / or in rotation, an elongated flexible medical instrument, the robotic system comprising a drive member capable of coming into contact with the elongated flexible medical instrument and kinematically connected to the actuator so that the latter controls the movement of said drive member along a so-called main axis, the control method being implemented by a data processing unit and comprising the following steps: measuring a speed of movement of the drive member along the main axis, measuring a force exerted by the elongated flexible medical instrument on the drive member along the main axis, and moving the drive member along the main axis, in a first direction,with: o transmission to the actuator of a primary control signal adapted to converge the measured movement speed towards a predetermined speed setpoint as long as the measured force is below a non-zero predetermined force threshold, and o transmission to the actuator of a secondary control signal adapted to converge the measured force towards a predetermined force setpoint when the measured force exceeds said force threshold.,

[0016] According to particular embodiments of the invention, the control method also has one or more of the following characteristics, taken in isolation or in any technically possible combination(s): the main axis consists of a clamping axis of the elongated flexible medical instrument, the first direction being oriented towards the elongated flexible medical instrument; the method comprises the following additional steps: o measuring a position of the drive member along the main axis, and o moving the drive member along the main axis in a second direction opposite to the first direction, with transmission to the actuator of a tertiary control signal adapted to converge the measured position towards a predetermined position setpoint;the method comprises, between the steps of moving in the first direction and in the second direction, an additional step of immobilizing the drive member along the main axis during which a quaternary control signal is transmitted to the actuator, adapted to maintain the measured force substantially equal to the force setpoint; the method comprises, during the step of immobilizing the drive member along the main axis, moving the drive member along at least one axis orthogonal to the main axis; the steps of moving in the first direction and in the second direction are implemented one after the other, in a cyclically repeated manner; the measured position is deduced from a current position of the actuator;the method comprises an additional step of measuring a position of the drive member along the main axis, the speed setpoint having a first value as long as the measured position is below a predetermined position threshold and a second value, lower than the first value, when the measured position is beyond said position threshold; the position threshold is such that when the measured position is equal to said position threshold the drive member is not in contact with the elongated flexible medical instrument; the force setpoint is greater than the force threshold; the measured movement speed is deduced from a current speed of the actuator; the measured force is deduced from a current supply power of the actuator; the measured force is measured directly by a strain sensor; the elongated flexible medical instrument consists of a catheter or a catheter guide;the force exerted by the drive member on the elongated flexible medical instrument does not exceed a predetermined limit threshold, preferably less than or equal to 30N; and the method does not comprise a step of determining the distance between the drive member and the elongated flexible medical instrument.;

[0017] The invention also relates, according to a second aspect, to a robotic system for driving an elongated flexible medical instrument, said robotic system comprising a frame, a drive member capable of coming into contact with the elongated flexible medical instrument, an actuator kinematically connected to the drive member so as to control the movement of said drive member relative to the frame along a main axis, and a data processing unit for implementing a method according to the first aspect.

[0018] The invention also relates, according to a third aspect, to a computer program product comprising code instructions for implementing a control method according to the first aspect when said computer program product is executed by a processor of a data processing unit of a robotic system for driving an elongated flexible medical instrument. The invention finally relates, according to a fourth aspect, to a storage means readable by computer equipment on which a computer program product according to the third aspect is recorded.

[0019] BRIEF DESCRIPTION OF THE FIGURES

[0020] Other characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which: Figure 1 is a schematic side view of an example of an angioplasty installation comprising a robotic system according to an embodiment of the invention, Figure 2 is a schematic perspective view of the robotic system of the installation of Figure 1, Figures 3A to 3E schematically represent several successive stages of rotational driving of an elongated flexible medical instrument by the robotic system of Figure 2, Figures 4A to 4G schematically represent several successive stages of translational driving of an elongated flexible medical instrument by the robotic system of Figure 2, Figure 5 is a functional diagram of a control unit of the robotic system of Figure 2,Figure 6 is a diagram illustrating a method for controlling actuators of the robotic system of Figure 2, and Figure 7 is a diagram illustrating the time evolution of various parameters of the robotic system of Figure 2 when the control method of Figure 6 is applied.,

[0021] DETAILED DESCRIPTION OF AN EXAMPLE OF IMPLEMENTATION

[0022] The angioplasty installation 1 shown in Figure 1 comprises a robot 3 for introducing an elongated flexible medical instrument 5 into an anatomical conduit of a patient 7, typically into a blood vessel of said patient 7. It also comprises an angiography system 10 for tracking the movement of the medical instrument 5 inside the body of the patient 7.

[0023] The angioplasty installation 1 is here distributed between an operating room 12 and a control room 14. In one embodiment, this control room 14 is close to the operating room 12 and is for example separated from it by a simple wall 16 opaque to X-rays. In another embodiment, the control room 14 is distant from the operating room 12. As a variant (not shown), the angioplasty installation 1 is entirely arranged in the operating room 12 alone.

[0024] The robot 3 comprises a robotic system 20 for driving the medical instrument 5, placed in the operating room 12 near the patient 7.

[0025] The robot 3 also comprises a control station 22 for controlling the robotic system 20 by an operator. Here, this control station 22 is a remote control station placed in the control room 1 and communicating with the robotic system 20 via a communication box 24 connected to the robotic system 20.

[0026] In the example shown, the robot 3 also comprises a local control box 26, arranged in the operating room 12, for the control of the robotic system 20 by an operator directly from the operating room 12.

[0027] The angiography system 10 comprises a medical imager 30, in particular an X-ray imager, comprising a source 32 and a detector 34 arranged on either side of the patient 7, possibly movable relative to the patient 7.

[0028] The angiography system 10 also comprises at least one screen 36, 38 communicating with the imager 30 for the real-time display of the images acquired by the imager 30. Here, the screens 36, 38 comprise a remote screen 36 installed in the control room 14 and a local screen 38 installed in the operating room 12. Alternatively (not shown), the angiography system 10 comprises only the remote screen 36 or the local screen 38.

[0029] The angiography system 10 further comprises at least one control 40, 42 communicating with the imager 30 to control the image capture by the imager 30. Here, the controls 40, 42 comprise a remote control 40 installed in the control room 14 and a local control 42 installed in the operating room 12. Alternatively (not shown), the angiography system 10 comprises only the remote control 40 or the local control 42.

[0030] The angiography system 10 finally comprises a contrast product injector 44 for injecting, inside the medical instrument 5, a contrast product facilitating the imaging of said medical instrument 5, a connector 46 connecting the injector 44 to the medical instrument 5 to guide the contrast product from the injector 44 to the inside of the medical instrument 5, and at least one control 47, 48 for controlling the injector 44. Here, the controls 47, 48 comprise a remote control 47 installed in the control room 14 and a local control 48 installed in the operating room 12. Alternatively (not shown), the angiography system 10 comprises only the remote control 47 or the local control 48.

[0031] The elongated flexible medical instrument 5 is elongated along an elongation axis. It consists of a medical instrument capable of being inserted into an anatomical conduit, typically a blood vessel, of the patient 7, and of being moved in said anatomical conduit through a hole providing an access opening in the patient 7. This elongated flexible medical instrument 5 is typically constituted by a catheter or by a catheter guide.

[0032] A catheter is, as is known, made up of a flexible and elongated tube, which is generally hollow over a portion close to the patient 7, or even over its entire length. Optionally, the catheter is equipped, at its distal end (opposite the robot 3), with a medical tool such as a balloon, an endoprosthesis, etc.

[0033] A guide is, as is known, a medical instrument configured to guide the catheter to an implantation site in the body of the patient 7. For this purpose, the guide is generally constituted by a cylinder with a transverse diameter smaller than that of the catheter so that the catheter can be placed around the guide and slide along the guide under the effect of a force initiated by the robot 3 or by an operator until its free end reaches the desired implantation site. Optionally, the guide has a curved end, so as to facilitate its navigation in the blood network of the patient 7.

[0034] To move the elongated flexible medical instrument 5 inside the body of the patient 7, it is desirable to be able to translate said instrument 5 along its axis of elongation and to be able to rotate it around said axis of elongation. Reference may be made to document FR 3 044 541 for further details regarding the usefulness of these movements.

[0035] The robotic system 20 is configured to drive the elongated flexible medical instrument 5 so as to give it at least one of these movements, here both.

[0036] For this purpose, the robotic system 20 comprises, with reference to Figure 2, a frame 50 and at least one, here two, drive module(s) 52, 52' each configured to drive the medical instrument 5 relative to the frame 50: in translation along an axis X, X' of extension of the medical instrument 5 at the level of said drive module 52, 52' here referred to as the longitudinal axis, and in rotation around said longitudinal axis X, X'.

[0037] It will be noted that said longitudinal axis X, X' is most often different from the extension axis of the medical instrument 5 at its distal end; nevertheless, a translation and / or a rotation of the medical instrument 5 along / around the longitudinal axis X, X', therefore along / around its elongation axis at the level of the robotic system 20 will cause a translation and / or a rotation of the medical instrument 5, respectively, along / around its elongation axis at its distal end.

[0038] In the example shown, each drive module 52, 52' comprises a pair of drive members 54, 56 together forming a gripper configured to grip and move the medical instrument 5 relative to the frame 50.

[0039] For this purpose, at least one of said drive members 54, 56, here each of the drive members 54, 56, is mounted to move in translation relative to the frame 50 along a clamping axis Y, Y' orthogonal to the longitudinal axis X, X' and substantially intersecting the axis of the medical instrument 5. The drive members 54, 56 are movable relative to each other along this clamping axis Y, Y' between a spaced apart position, in which the drive members 54, 56 are at a distance from each other, and a close position in which the drive members 54, 56 are close to each other.

[0040] Each drive member 54, 56 of a pair is furthermore movable in translation relative to the frame 50 along at least one other axis substantially orthogonal to the clamping axis Y, Y'. Each drive member 54, 56 of a pair is thus movable in translation relative to the frame 50 along at least one of the following axes: the longitudinal axis X, X', and a transverse axis Z, Z' substantially orthogonal to the clamping axes Y, Y' and longitudinal X, X'.

[0041] The two drive members 54, 56 of each drive module 52, 52' have in particular the same degrees of freedom along the longitudinal axis X, X', that is to say that for each drive module 52, 52' of which one of the drive members 54, 56 is movable in translation along the longitudinal axis X, X', the other drive member 54, 56 of said drive module 52, 52' is also movable in translation along said longitudinal axis X, X'. Advantageously, the two drive members 54, 56 of each drive module 52, 52' also have the same degrees of freedom along the transverse axis Z, Z'.

[0042] Here, each drive member 54, 56 of each drive module 52, 52' is movable in translation relative to the frame 50 along each of the longitudinal axes X, X' and transverse axes Z, Z'.

[0043] Preferably, the drive modules 52, 52' are arranged so that the longitudinal axes X, X' are, as shown, substantially coincident. In the following, for simplification, reference will therefore simply be made to the longitudinal axis X, the clamping axis Y and the transverse axis Z.

[0044] Each drive member 54, 56 delimits a drive surface, respectively 58, 59, configured to be spaced apart from the medical instrument 5 when the drive members 54, 56 are in the spaced apart position and in contact with the medical instrument 5 when the drive members 54, 56 are in the close position. Said drive surfaces 54, 56 face each other and are spaced apart from each other along the Y axis. Each drive surface 58, 59 has in particular a normal substantially parallel to the Y axis.

[0045] Each drive member 54, 56 is typically formed of a key holder (not shown) and a removable key (not shown) mounted on the key holder and delimiting the drive surface 58, 59. The drive surface 58, 59 in contact with the medical instrument 5 can thus be changed each time the robot 3 is used, which makes it possible to preserve the sterility of the medical instrument 5.

[0046] Each drive module 52, 52' also comprises a drive device 60 for controlling the movement of the drive members 54, 56 of said module 52, 52' along the Y axis and, where appropriate, the X and / or Z axis. This drive device 60 comprises at least one actuator 62, 63, 64, 65, 66, 67 and, for the or each actuator 62, 63, 64, 65, 66, 67, a kinematic chain, respectively 72, 73, 74, 75, 76, 77 kinematically connecting said actuator 62, 63, 64, 65, 66, 67 to at least one of the drive members 54, 56 so that the latter controls the movement of said drive member 54, 56 along at least one of the X, Y, Z axes.

[0047] According to a possible variant, as shown, each kinematic chain 72, 73, 74, 75, 76, 77 kinematically connects an actuator 62, 63, 64, 65, 66, 67 to only one of the drive members 54, 56. Each actuator 62, 63, 64, 65, 66, 67 thus controls the movement of only one of the drive members 54, 56. The drive device 60 is thus formed of two drive sub-devices 80, 82, each specific to one of the drive members 54, 56.

[0048] Here, each drive sub-device 80, 82 comprises three actuators, respectively 62, 63, 64 and 65, 66, 67. Each actuator 62, 63, 64, 65, 66, 67 contributes to the movement of the drive member, respectively 54, 56, along at least one of the axes X, Y, Z. Advantageously, each actuator 62, 63, 64, 65, 66, 67 contributes to the movement of the drive member, respectively 54, 56, along a single axis, specific to said actuator 62, 63, 64, 65, 66, 67, among the axes X, Y, Z or, failing that, has a majority contribution along an ... axes X, Y, Z, that is to say that the contribution of said actuator 62, 63, 64, 65, 66, 67 to the displacement of the drive member 54, 56 along said own axis is large compared to the contribution of the actuator 62, 63, 64, 65, 66, 67 to the displacement of the drive member 54, 56 along each of the other axes.Thus, in the example shown: the actuators 62, 65 contribute mainly or exclusively to the movement of the drive members 54, 56 along the X axis, the actuators 63, 66 contribute mainly or exclusively to the movement of the drive members 54, 56 along the Y axis, and the actuators 64, 67 contribute mainly or exclusively to the movement of the drive members 54, 56 along the Z axis.

[0049] For this purpose, each sub-drive device 80, 82 is typically constituted by a drive device as described in WO 2022 / 144267, the content of which is incorporated herein by reference.

[0050] Each actuator 62, 63, 64, 65, 66, 67 consists for example of an electric motor comprising a rotor and a stator (not shown), the stator being fixed relative to the frame 50 and the rotor forming the part of the actuator 62, 63, 64, 65, 66, 67 kinematically connected to the drive member 54, 56.

[0051] The robotic system 20 also comprises sensors 84, 85 for measuring a clamping force, a speed of movement and a position of the drive members 54, 56 of each module 52, 52' along the Y axis. Here, the robotic system 20 additionally comprises sensors 87, 88 for also measuring a position of the drive members 54, 56 of each module 52, 52' along each of the X and Z axes.

[0052] The sensors 84, 85, 87, 88 are here indirect sensors, that is to say they provide data representative of the clamping force, the speed of movement along the Y axis and the position of the drive members 54, 56 of each module 52, 52' by indirect measurements, here by measurements on the actuators 62, 63, 64, 65, 66, 67. These indirect measurements are for example a measurement of the supply current of the actuators 62, 63, 64, 65, 66, 67 and a measurement of the position of the actuators 62, 63, 64, 65, 66, 67 (typically, in the case of electric motors, the position of the rotor relative to the stator).It is indeed known that there are transfer functions linking: the electrical power consumed by an actuator to the force exerted by a member driven by said actuator, the speed of an actuator to the speed of movement of a member driven by said actuator, and the position of an actuator to the position of a member driven by said actuator, these transfer functions depending on the kinematic chain linking the actuator to the member that it drives. Those skilled in the art will easily be able to find these transfer functions to deduce the clamping force, the speed of movement along the Y axis and the position of the drive members 54, 56 of each module 52, 52' from the measurements provided by the sensors 84, 85, 87, 88.

[0053] Alternatively (not shown), the sensors 84, 85, 87, 88 are direct sensors, i.e. they directly measure the clamping force, the speed of movement along the Y axis and the position of the drive members 54, 56 of each module 52, 52'.

[0054] The robotic system 20 also comprises a unit 90 for controlling the actuators 62, 63, 64, 65, 66, 67 of each drive module 52, 52', capable of transmitting to each of said actuators 62, 63, 64, 65, 66, 67 a control signal for the latter.

[0055] This control unit 90 is here produced in the form of a data processing unit comprising a processor or CPU (“Central Processing Unit” in English) 92, a memory 94 of the RAM (“Random Access Memory” in English) and / or ROM (“Read Only Memory” in English) type, and a storage module 96 of the internal storage type.

[0056] The storage module 96 is for example of the HDD (“Hard Disk Drive”) or SSD (“Solid-State Drive”) type, or of the external storage media reader type, such as an SD (“Secure Digital”) card reader.

[0057] The processor 92 is configured to record data, or information, in the memory 94 or in the storage module 96 and / or read data recorded in the memory 94 or in the storage module 96.

[0058] The processor 92 is configured to execute instructions loaded into the memory 94, for example from the storage module 96. When the robotic system 20 is powered on, the processor 92 is capable of reading instructions from the memory 94 and executing them. These instructions form a computer program causing the implementation, by the processor 92, of all or part of a method 200 for controlling the actuators 62, 63, 64, 65, 66, 67 which will be described later. Thus, all or part of the method 200 can be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller.

[0059] Alternatively (not shown), the control unit 90 is produced in the form of a data processing unit consisting at least in part of a machine or a dedicated component, such as an FPGA (“Field-Programmable Gate Array”) or an ASIC (“Application-Specific Integrated Circuit”), to implement all or part of the method 200.

[0060] It will be noted that, although represented here in the form of a single unit common to all the actuators 62, 63, 64, 65, 66, 67, the control unit 90 can alternatively be produced in the form of several units distributed at the level of each drive device 60 or at the level of each sub-device 80, 82, or even at the level of each actuator 62, 63, 64, 65, 66, 67, said distributed units then being synchronized by means of a shared synchronization signal.

[0061] The control unit 90 is in particular configured to control the actuators 62, 63, 64, 65, 66, 67 so as to drive the rotation of the medical instrument 5 around its elongation axis by simultaneous movement, in opposite directions, of the drive members 54, 56 of the same pair along the Z axis. For this purpose, the control unit 90 is typically configured to control the implementation of the following steps, illustrated in Figures 3A to 3E: positioning the drive members 54, 56 in the spaced-apart position, their respective drive surfaces 58, 59 not being in contact with the medical instrument 5 (Figure 3A); bringing together the drive members 54, 56 by translation of said members 54, 56 in opposite directions along the Y axis, until their respective drive surfaces 58, 59 grip the medical instrument 5 (Figure 3B);displacement of the drive members 54, 56 in translation along the Z axis, in opposite directions to each other, so as to rotate the medical instrument 5 around its axis in one direction or the other, the drive surfaces 58, 59 keeping the medical instrument 5 gripped during this displacement (Figure 3C); moving the drive members 54, 56 away from the medical instrument 5 by translation of said members 54, 56 in opposite directions along the Y axis, until reaching a predetermined position in which the drive surfaces 58, 59 release the medical instrument 5 and then cease to be in contact with the medical instrument 5 (Figure 3D);and repositioning the drive members 54, 56 by translation of said members 54, 56 in opposite directions along the Z axis, their respective drive surfaces 58, 59 remaining distant from the medical instrument 5 so as not to drive the medical instrument 5 in rotation, until the drive members 54, 56 return to their original position (Figure 3E). The control unit 90 is in particular configured to control the cyclic repetition of these steps, so as to allow a complete rotation of the medical instrument 5 in one direction as in the other.;

[0062] The control unit 90 is also configured to control the actuators 62, 63, 64, 65, 66, 67 so as to drive the translation of the medical instrument 5 along its axis by simultaneous movement, in the same direction, of the drive members 54, 56 of the same pair along the X axis. For this purpose, the control unit 90 is typically configured to control the implementation of the following steps, illustrated in Figures 4A to 4G: positioning the drive members 54, 56 of each drive module 50, 50' in the spaced-apart position, their respective drive surfaces 58, 59 not being in contact with the medical instrument 5 (Figure 4A);bringing together the drive members 54, 56 of a first drive module 50 by translation of said members 54, 56 in opposite directions along the Y axis, until their respective drive surfaces 58, 59 grip the medical instrument 5, the drive members 54, 56 of the second drive module 50' remaining away from the medical instrument 5 (Figure 4B); displacement of the drive members 54, 56 of the first drive module 50 in translation along the X axis, synchronously and in the same first direction, so as to drive the medical instrument 5 in translation along its axis in said first direction, the drive surfaces 58, 59 of the first drive module 50 keeping the medical instrument 5 gripped during this displacement, while the drive members 54, 56 of the second drive module 50' remain stationary away from the medical instrument 5 (Figure 4G);moving the drive members 54, 56 of the first drive module 50 away from the medical instrument 5 by translation of said members 54, 56 in opposite directions along the Y axis, until reaching a predetermined position in which the drive surfaces 58, 59 of said members 54, 56 release the medical instrument 5 and then cease to be in contact with the medical instrument 5, and simultaneously moving the drive members 54, 56 closer to the second drive module 50' by translation of said members 54, 56 in opposite directions along the Y axis, until their respective drive surfaces 58, 59 grip the medical instrument 5 (Figure 4D);displacement of the drive members 54, 56 of the second drive module 50' in translation along the X axis, synchronously and in the first direction, so as to drive the medical instrument 5 in translation along its axis in the first direction, the drive surfaces 58, 59 of the second drive module 50' keeping the medical instrument 5 gripped during this displacement, and simultaneous displacement of the drive members 54, 56 of the first drive module 50 in translation along the X axis, synchronously and in the second direction, their respective drive surfaces 58, 59 remaining distant from the medical instrument 5 so as not to drive the medical instrument 5, until the drive members 54, 56 of the first drive module 50 return to their original position (Figure 4E);moving the drive members 54, 56 of the second drive module 50' away from the medical instrument 5 by translation of said members 54, 56 in opposite directions along the Y axis, until reaching a predetermined position in which the drive surfaces 58, 59 of said members 54, 56 release the medical instrument 5 and then cease to be in contact with the medical instrument 5, and simultaneously moving the drive members 54, 56 closer to the first drive module 50 by translation of said members 54, 56 in opposite directions along the Y axis, until their respective drive surfaces 58, 59 grip the medical instrument 5 (Figure 4F);displacement of the drive members 54, 56 of the first drive module 50 in translation along the X axis, synchronously and in the first direction, so as to drive the medical instrument 5 in translation along its axis in the first direction, the drive surfaces 58, 59 of the first drive module 50 keeping the medical instrument 5 gripped during this displacement, and simultaneous displacement of the drive members 54, 56 of the second drive module 50' in translation along the X axis, synchronously and in the second direction, their respective drive surfaces 58, 59 remaining distant from the medical instrument 5 so as not to drive the medical instrument 5, until the drive members 54, 56 of the second drive module 50' return to their original position (Figure 4G).;

[0063] The control unit 90 is preferably configured to control the cyclic repetition of the steps of Figures 4D to 4G, so as to allow the lengthening of the movement stroke of the medical instrument 5 along the X axis.

[0064] The control unit 90 is in particular configured so that, when the drive members 54, 56 are brought together, that is to say during the steps illustrated by Figures 3B, 4B, 4D and 4F, the clamping force exerted by the drive members 54, 56 does not exceed a predetermined limit threshold. Preferably, the limit threshold is less than or equal to 3ON, thus reducing the risk of damaging the medical instrument 5, in particular when the medical instrument 5 is a catheter.

[0065] For this purpose, the control unit 90 comprises, for each drive sub-device 80, 82, a sub-unit 98 for controlling said sub-device 80, 82. With reference to Figure 5, this control sub-unit 98 comprises a module 100 for controlling the actuators 62, 63, 64, 65, 66, 67 in position, a module 102 for controlling the actuators 62, 63, 64, 65, 66, 67 in speed and a module 104 for controlling the actuators 62, 63, 64, 65, 66, 67 in force.

[0066] The position control module 100 comprises a first input 110 for receiving a predetermined position setpoint along each of the displacement axes of the drive member 54, 56 driven by the sub-device 80, 82 (therefore here along each of the X, Y and Z axes) and a second input 112 for receiving a measurement of the position of said drive member 54, 56 along each of its displacement axes (therefore here along each of the X, Y and Z axes). The position control module 100 is configured to generate, as a function of these inputs, for each of the displacement axes of the drive member 54, 56, a position control signal adapted to converge the measured position along said displacement axis towards the corresponding position setpoint.It further comprises, for each axis of movement of the drive member 54, 56, a respective output 114, 116, 188 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned (i.e. to each actuator acting on the movement of the drive member along said axis of movement) this position control signal.Thus, in the example shown, said outputs 114, 116, 118 comprise: a first output 114 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned a position control signal adapted to converge the position measured along the X axis towards the position setpoint along the X axis, a second output 116 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned a position control signal adapted to converge the position measured along the Y axis towards the position setpoint along the Y axis, and a third output 118 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned a position control signal adapted to converge the position measured along the Z axis towards the position setpoint along the axis Z.The speed control module 102 comprises a first input 120 for receiving a speed setpoint along the clamping axis Y and a second input 122 for receiving a measurement of the speed of the drive member 54, 56 driven by the sub-device 80, 82 along the clamping axis Y. The speed control module 102 is configured to generate, as a function of these inputs, a speed control signal adapted to converge the measured speed towards the speed setpoint. It further comprises an output 124 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned (i.e. to each actuator acting on the movement of the drive member along the clamping axis Y) this speed control signal.

[0067] The force control module 104 comprises a first input 130 for receiving a predetermined force setpoint along the clamping axis Y and a second input 132 for receiving a measurement of the force exerted by the medical instrument 5 on the drive member 54, 56 driven by the sub-device 80, 82 along the clamping axis Y. The force control module 104 is configured to generate, as a function of these inputs, a force control signal adapted to converge the measured force towards the force setpoint. It further comprises an output 134 for transmitting to each actuator 62, 63, 64, 65, 66, 67 concerned (i.e. to each actuator acting on the movement of the drive member along the clamping axis Y) this force control signal.

[0068] The force setpoint is strictly lower than the limit threshold. For example, it is lower than 90% of the limit threshold, preferably between 80 and 90% of the limit threshold.

[0069] The control sub-unit 98 also comprises a switch 140 for switching the control of the actuators 62, 63, 64, 65, 66, 67 in clamping between position control, speed control and force control. For this purpose, the switch 140 comprises a first input 142 for receiving the position control signal, a second input 143 for receiving the speed control signal, and a third input 144 for receiving the force control signal. It further comprises an output 145 for transmitting a clamping control signal to each actuator 62, 63, 64, 65, 66, 67 concerned (i.e. to each actuator acting on the movement of the drive member along the clamping axis Y). The switch 140 further comprises a fourth input 146 for receiving a measurement of the force exerted by the medical instrument 5 on said drive member 54,56 along the clamping axis Y and a fifth input 147 for receiving information regarding the current movement phase along the clamping axis Y (approaching or separating the drive members 54, 56). The switch 140 is configured to connect the output 145 selectively to the first, second or third input 142, 143, 144 depending on the fourth and fifth inputs 146, 147. In particular, the switch 140 is configured to switch between three configurations: a first configuration in which it connects the output 145 to the first input 142, i.e. it transmits as a clamping signal the position control signal to the actuators 62, 63, 64, 65, 66, 67 concerned, when the fifth input 147 indicates that the current movement phase along the clamping axis Y is a phase of separation of the drive members 54, 56 (i.e. typically during the steps illustrated by Figures 3D, 4D and 4F),whatever the value of the fourth input 146; a second configuration in which it connects the output 145 to the second input 143, that is to say it transmits as a clamping signal the speed control signal to the actuators 62, 63, 64, 65, 66, 67 concerned, when the fifth input 147 indicates that the current movement phase along the clamping axis Y is a phase of bringing the drive members 54, 56 together and that the measured clamping force received on the fourth input 146 is less than or equal to a predetermined switching threshold; and a third configuration in which it connects the output 145 to the third input 144, that is to say it transmits as a clamping signal the force control signal to the actuators 62, 63, 64, 65, 66, 67 concerned, when the fifth input 147 indicates that the current movement phase along the clamping axis Y is a phase of bringing the drive members 54 together,56 and that the measured clamping force received on the fourth input 146 is strictly greater than the predetermined switching threshold.

[0070] The predetermined switching threshold is strictly lower than the force setpoint.

[0071] The clamping signal is typically constituted by an electrical signal controlling, for each actuator 62, 63, 64, 65, 66, 67 concerned, the switching of the power switches of a current supply member of said actuator 62, 63, 64, 65, 66, 67.

[0072] The control sub-unit 98 further comprises a speed setpoint generator 150. This generator 150 comprises an input 152 for receiving a measurement of the position of the drive member 54, 56 driven by the sub-device 80, 82 along the clamping axis Y and an output 154 for transmitting the speed setpoint to the speed control module 102. The generator 150 is configured to compare the measured position to a predetermined position threshold and to give the speed setpoint a first predetermined value when the measured position is less than or equal to the position threshold and a second predetermined value, strictly less than the first value, when the measured position is strictly greater than the position threshold.

[0073] The second value of the speed setpoint is preferably less than 90% of the first value, for example less than 60%, advantageously between 60 and 40% of the first value. Furthermore, the second value is preferably less than the movement speed achievable by the drive member 54, 56 when it moves from its original position to the position threshold.

[0074] The position threshold is such that when the measured position is equal to said position threshold, the drive member 54, 56 is not in contact with the medical instrument 5. The position threshold is preferably obtained from the maximum diameter of the different medical instruments that the drive member 54, 56 is capable of handling. Indeed, knowing the maximum diameter of the medical instrument 5 that the drive member 54, 56 can receive, it is possible to determine that before a given position it is not possible for the drive member 54, 56 to come into contact with the medical instrument 5. This makes it possible in particular to dispense with the measurement of the distance separating the drive member 54, 56 and the medical instrument 5, a measurement that may require a visual control device.

[0075] The method 200 implemented by the control unit 90 will now be described, with reference to Figures 6 and 7. For simplification, the description given here concerns the control of only the actuators 62, 63, 64 of the same drive sub-device 80 driving a single drive member 54. Those skilled in the art will easily be able to deduce the control of the other actuators.

[0076] This method 200 firstly comprises a force measurement step 202, a speed measurement step 204 and a position measurement step 206.

[0077] The force measurement step 202 comprises measuring the force exerted by the medical instrument 5 on the drive member 54 along the clamping axis Y. This force is typically deduced, as described above, from the power supply to the actuators 62, 63, 64. Alternatively, this force is measured directly by a strain sensor.

[0078] The speed measurement step 204 comprises measuring the speed of movement of the drive member 54 along the clamping axis Y. This speed is typically deduced, as described above, from the current speed of at least one of the actuators 62, 63, 64. For example, the speed of movement of the drive member 54 along the clamping axis Y is deduced from the current speed of the actuator 63 (i.e., of the actuator contributing mainly or exclusively to the movement of the drive member 54 along the Y axis). The position measurement step 206 comprises measuring the position of the drive member 54 along the clamping axis Y. This position is typically deduced, as described above, from the current position of at least one of the actuators 62, 63, 64.For example, the position of the drive member 54 along the clamping axis Y is deduced from the current position of the actuator 63 (i.e. of the actuator contributing mainly or exclusively to the movement of the drive member 54 along the Y axis).

[0079] These steps 202, 204, 206 are repeated throughout the implementation of the method 200, at a predetermined sampling frequency, possibly variable but preferably constant.

[0080] The method 200 then comprises a step 210 of clamping the medical instrument 5. During this step 210, the control unit 90 controls the actuators 62, 63, 64 so as to bring the drive member 54 closer to the drive member 56. This step 210 is typically implemented during the steps illustrated by Figures 3B, 4B, 4D and 4F.

[0081] Step 210 firstly comprises the comparison 212 of the measured force with the switching threshold. If the measured force is less than or equal to said threshold, this comparison 212 is followed by the transmission 214 to the actuators 62, 63, 64 of a first control signal. If the measured force is strictly greater than said threshold, this comparison 212 is followed by the transmission 216 to the actuators 62, 63, 64 of a second control signal.

[0082] During the transmission step 214, the switch 140 is in the second configuration: the first control signal is therefore constituted by the speed control signal. The first control signal is thus adapted to converge the measured movement speed towards the speed setpoint provided by the generator 150.

[0083] This transmission step 214 comprises the comparison 217 of the measured position of the drive member 54 along the Y axis with the position threshold. If the measured position is less than or equal to said threshold, this comparison 217 is followed by the allocation 218 of the first value to the speed setpoint; in other words, the generator 150 confers the first value to the speed setpoint. If the measured position is strictly greater than said threshold, this comparison 217 is followed by the allocation 219 of the second value to the speed setpoint; in other words, the generator 150 confers the second value to the speed setpoint.

[0084] After the implementation of the transmission step 214, the method 200 returns to the force comparison 212. During the transmission step 216, the switch 140 is in the third configuration: the second control signal is therefore constituted by the force control signal. The second control signal is thus adapted to converge the measured force towards the force setpoint.

[0085] The temporal implementation of this tightening step 210 is illustrated by Figure 7. Step 210 begins at a time to. At this time, the drive member 54 is still in its initial position along the Y axis; the measured position P has therefore not yet reached the position threshold SP. In addition, the drive member 54 is still away from the medical instrument 5; the measured force F is therefore zero. It is therefore the first control law which is transmitted, with a speed setpoint Cv at the first value Vi. The measured speed V therefore increases progressively, tending to converge towards the speed setpoint Cv.

[0086] However, at time ti, here even before the speed V has reached the setpoint Cv, the measured position P reaches the threshold SP. The drive member 54 is then still away from the medical instrument 5, so that the measured force F is still zero. The first control law therefore remains transmitted, but the value of the speed setpoint Cv is reduced to the second value V2. This being here lower than the value reached by the measured speed V at time ti, the speed V gradually decreases so as to tend towards the new value of the speed setpoint Cv. This initiates braking of the drive member 54.

[0087] It is during this slowing down phase that the drive member 54 comes into contact with the medical instrument 5, which causes an increase in the measured force F which then reaches the switching threshold SF at a time tz. This has the effect of stopping the transmission of the first control law to the actuators 62, 63, 64, and it is then the second control law which is transmitted, with a force setpoint CF equal to a value Fc which, as can be seen in this Figure 7, is strictly lower than a limit threshold Fmax which one does not wish to exceed. Under the effect of this new control law, the measured force F briefly exceeds the value Fc but without crossing the threshold F ma x then stabilizes at the CF force setpoint value.

[0088] The implementation of step 210 thus allows rapid movement of the drive member along the clamping axis Y, without crossing the limit threshold F ma x.

[0089] Returning to Figure 6, step 210 is followed by a step 220 of holding the medical instrument 5 clamped, during which the drive member 54 is substantially immobilized along the Y axis. This step 220 is typically implemented during the steps illustrated in Figures 3C, 4C, 4E and 4G.

[0090] This step 220 comprises the transmission 222 to the actuators 62, 63, 64 of a third control signal adapted to maintain the measured force substantially equal to the force setpoint. For this purpose, the switch 140 is typically maintained in its third configuration during this step 220.

[0091] Optionally, step 220 also comprises the displacement 224 of the drive member 54 along the longitudinal axis X and / or the displacement 226 of the drive member 54 along the transverse axis Z. This displacement is typically obtained by superimposing on the third control signal a position control signal along the X axis and / or along the Z axis provided by the position control module 100.

[0092] Step 220 is itself followed by a step 230 of loosening the medical instrument 5. During this step 220, the control unit 90 controls the actuators 62, 63, 64 so as to move the drive member 54 away from the drive member 56. This step 220 is typically implemented during the steps illustrated by Figures 3D, 4D and 4F.

[0093] Step 230 comprises the transmission 232 of a fourth control signal to the actuators 62, 63, 64. During step 230, the switch 140 is informed by its fifth input 147 that it is in a phase of separation of the drive members 54, 56 and is therefore switched to its first configuration. Thus, the fourth control signal consists of the position control signal. In other words, the fourth control signal is adapted to converge the measured position towards the position setpoint.

[0094] Step 230 is followed by a step 240 of holding the medical instrument 5 loose, during which the drive member 54 is substantially immobilized along the Y axis. This step 240 is typically implemented during the steps illustrated in Figures 3E, 4E and 4G.

[0095] This step 240 comprises the transmission 242 to the actuators 62, 63, 64 of a fifth control signal adapted to maintain the measured position along the Y axis substantially equal to the position setpoint. For this purpose, the switch 140 is typically maintained in its first configuration during this step 240.

[0096] Optionally, step 240 also comprises the displacement 244 of the drive member 54 along the longitudinal axis X and / or the displacement 246 of the drive member 54 along the transverse axis Z. This displacement is typically obtained by superimposing on the fifth control signal a position control signal along the X axis and / or along the Z axis provided by the position control module 100.

[0097] After step 240, the method 200 finally returns to step 210, the steps 210, 220, 230, 240 being thus repeated cyclically one after the other, as described above in connection with Figures 3A to 3E 4A to 4G. Thus, thanks to the exemplary embodiment described above, it is possible to move the drive members 54, 56 quickly along the clamping axis Y, while preventing the force exerted by the drive members 54, 56 on the medical instrument 5 along the Y axis from exceeding the limit threshold F ma x, which prevents damage to the medical instrument 5. Furthermore, the clamping force is maintained and controlled during the step 220 of holding the medical instrument 5 clamped, which again prevents damage to the medical instrument 5 and further ensures slip-free driving of the medical instrument 5 by the drive members 54, 56.

[0098] According to an additional embodiment variant, the drive members are rollers rotating around the Z axis, the rotation of said rollers around the Z axis making it possible to drive the medical instrument 5 in translation along the X axis. In addition, these rollers are movable in translation along the clamping axis Y in order to clamp or release the medical instrument 5. In addition, the rollers can be movable in translation along the Z axis in order to drive the medical instrument 5 in rotation around the X axis. Such a solution for the drive members is for example described in the patent application filed on April 26, 2022 under the number FR2203874. The clamping management described above when the drive members are key holders on which single-use keys are attached can be applied in a similar manner when the drive members are rotating rollers.

Claims

CLAIMS 1. Method (200) for controlling an actuator (62, 63, 64, 65, 66, 67) of a robotic system (20) for driving, in translation and / or in rotation, an elongate flexible medical instrument (5), the robotic system (20) comprising a drive member (54, 56) capable of coming into contact with the elongate flexible medical instrument (5) and kinematically connected to the actuator (62, 63, 64, 65, 66, 67) so that the latter controls the movement of said drive member (54, 56) along a so-called main axis (Y), the control method (200) being implemented by a data processing unit (90) and comprising the following steps: measuring (204) a speed of movement (V) of the drive member (54, 56) along the main axis (Y), measurement (206) of a force (F) exerted by the elongated flexible medical instrument (5) on the drive member (54, 56) along the main axis (Y), and displacement (210) of the drive member (54, 56) along the main axis (Y),in a first sense, with:, • transmission (214) to the actuator (62, 63, 64, 65, 66, 67) of a primary control signal adapted to converge the measured movement speed (V) towards a predetermined speed setpoint (Cv) as long as the measured force (F) is below a predetermined non-zero force threshold (SF), and • transmission (216) to the actuator (62, 63, 64, 65, 66, 67) of a secondary control signal adapted to converge the measured force (F) towards a predetermined force setpoint (CF) when the measured force (F) exceeds said force threshold (SF).

2. Control method (200) according to claim 1, wherein the main axis (Y) consists of a clamping axis of the elongated flexible medical instrument (5), the first direction being oriented towards the elongated flexible medical instrument (5).

3. Control method (200) according to claim 1 or 2, comprising the following additional steps: measurement (202) of a position (P) of the drive member (54, 56) along the main axis (Y), and movement (230) of the drive member (54, 56) along the main axis (Y) in a second direction opposite to the first direction, with transmission (232) to the actuator (62, 63, 64, 65, 66, 67) of a tertiary control signal adapted to converge the measured position (P) towards a predetermined position setpoint.

4. Control method (200) according to claim 3, comprising between the steps of movement in the first direction and in the second direction (210, 230) an additional step (220) of immobilizing the drive member (54, 56) along the main axis (Y) during which a quaternary control signal is transmitted to the actuator (62, 63, 64, 65, 66, 67) adapted to maintain the measured force (F) substantially equal to the force setpoint (CF).

5. Control method (200) according to claim 4, comprising during the step of immobilizing (220) the drive member (54, 56) along the main axis (Y) the displacement (224, 226) of the drive member (54, 56) along at least one axis (X, Z) orthogonal to the main axis (Y).

6. Control method (200) according to any one of claims 3 to 5, wherein the steps of moving in the first direction and in the second direction (210, 230) are implemented one after the other, in a cyclically repeated manner.

7. Control method (200) according to any one of claims 3 to 6, in which the measured position (P) is deduced from a current position of the actuator (62, 63, 64, 65, 66, 67).

8. Control method (200) according to any one of the preceding claims, comprising an additional step (202) of measuring a position (P) of the drive member (54, 56) along the main axis (Y), the speed setpoint (Cv) having a first value (Vi) as long as the measured position (P) is below a predetermined position threshold (SP) and a second value (V2), lower than the first value (V1), when the measured position (P) is beyond said position threshold (SP).

9. Control method (200) according to claim 8, wherein the position threshold (SP) is such that when the measured position (P) is equal to said threshold of position (SP) the drive member (54, 56) is not in contact with the elongated flexible medical instrument (5).

10. Control method (200) according to any one of the preceding claims, in which the force setpoint (CF) is greater than the force threshold (SF).

11. Control method (200) according to any one of the preceding claims, in which the measured displacement speed (V) is deduced from a current speed of the actuator (62, 63, 64, 65, 66, 67).

12. Control method (200) according to any one of the preceding claims, wherein the measured force (F) is deduced from a current supply power of the actuator (62, 63, 64, 65, 66, 67).

13. A control method (200) according to any preceding claim, wherein the elongate flexible medical instrument (5) consists of a catheter or a catheter guide.

14. Robotic system (20) for driving an elongated flexible medical instrument (5), said robotic system (200) comprising a frame (50), a drive member (54, 56) capable of coming into contact with the elongated flexible medical instrument (5), an actuator (62, 63, 64, 65, 66, 67) kinematically connected to the drive member (5) so as to control the movement of said drive member (54, 56) relative to the frame (5) along a main axis (Y), and a data processing unit (90) for implementing a method (200) according to any one of the preceding claims.

15. Computer program product comprising code instructions for implementing a control method (200) according to any one of claims 1 to 13 when said computer program product is executed by a processor (92) of a data processing unit (90) of a robotic system (20) for driving an elongated flexible medical instrument (5).

Images