Collaborative medical robot to guide the insertion of instruments

Abstract

The invention relates to a medical robot (10) for assisting a practitioner during a minimally invasive medical procedure. The medical robot comprises a robotic arm (13) equipped with a tool guide (14) to guide the insertion of a medical instrument (15) into the body of a patient (20) along a planned trajectory. A control unit (12) of the medical robot is configured to perform a sequence of movements of the robotic arm (13) comprising successively an automatic movement to move the tool guide (14) to a remote position (102), and a cooperative manual movement to move the tool guide (14) from the remote position to an insertion position (103). The only possible movements of the tool guide (14) during the cooperative manual movement are translation along a principal axis of the tool guide (14) and optionally rotation around the axis of the planned trajectory (41).This sequence of movements allows for the precise and safe repositioning of the tool guide to re-engage a medical instrument already partially inserted into the patient's body. Figure for the abbreviation: Fig. 10.

Description

Title of the invention: Collaborative medical robot to guide the insertion of instruments Scope of the invention

[0001] The present invention belongs to the field of robotic devices for assisting a practitioner during a medical procedure. In particular, the invention relates to a collaborative medical robot for guiding the insertion of a medical instrument during a minimally invasive medical procedure. State of the art

[0002] Medical interventions performed by minimally invasive or percutaneous means may require the insertion by a practitioner of one or more medical instruments (for example a needle, a probe, a catheter, etc.) into a patient's body to a certain depth to reach a target anatomical area (for example a tumor in the liver, a lung, a kidney or a bone).

[0003] To improve the precision of the insertion procedure and limit radiation doses to the patient, automatically controlled robotic arms can be used. The robotic arm can be equipped with a tool guide to guide a medical instrument. For example, the practitioner indicates on a pre-procedure medical image a trajectory that the medical instrument must follow to reach a target area of ​​the patient's anatomy of interest, and the robotic arm automatically moves into a position such that the tool guide allows the medical instrument to be guided along the planned trajectory.

[0004] In order to verify that the medical instrument follows the planned trajectory, it may be necessary to acquire one or more control medical images during insertion. Indeed, the trajectory of the medical instrument may be deviated when it pierces the patient's skin at the entry point or the surface of an organ (for example, the liver capsule) or when it passes through cortical bone.

[0005] When the medical instrument is inserted, it is held in place by the tool guide. To acquire the control medical images, it is necessary to release the medical instrument from the guide. After acquiring the control images, if the instrument follows the planned trajectory, or if the deviation of the instrument from the planned trajectory can be corrected by slightly modifying the planned trajectory, the insertion can be continued, which requires repositioning the medical instrument in the tool guide. To perform this repositioning, it is possible to automatically send the robotic arm to the insertion position while manually moving the medical instrument away to avoid a Collision between the tool guide and the medical instrument. This solution is not optimal because it can cause the medical instrument to deviate from the planned trajectory.

[0006] Another solution could be to use a free manual movement mode for the robotic arm to reposition the medical instrument in the tool guide. This solution is also not optimal because it requires a very high degree of ease (transparency) in the manual movement of the robotic arm (particularly for adjusting the orientation of the tool guide) and it does not guarantee sufficient positioning accuracy for the tool guide.

[0007] French patent application FR3120777A1 describes various control methods for a robotic arm, including a cooperative manual control method for releasing and returning the tool guide to a predetermined insertion position. In this control method, it is necessary for the patient to be returned exactly to the position they were in relative to the robot before the tool guide was released. If the robot or the patient moves between the release and repositioning of the tool guide, it is not possible to return the guide to a correct insertion position relative to the patient. Furthermore, it is not possible to replan a new path if the trajectory deviates. Description of the invention

[0008] The solution presented in this application aims to remedy all or part of the disadvantages of the prior art, in particular those set out above.

[0009] To this end, and according to a first aspect, a medical robot is proposed to assist a practitioner during a minimally invasive medical procedure on a patient's anatomy of interest. The medical robot comprises a robotic arm, the distal end of which is equipped with a tool guide designed to guide the insertion of at least part of a medical instrument into the patient's body along a planned trajectory. The tool guide is coupled to a force sensor. The medical robot includes a control unit configured to control the robotic arm in order to move the tool guide. The control unit is configured to determine, from the planned trajectory, an insertion position and an offset position of the tool guide, and to perform a sequence of movements of the robotic arm comprising successively: - an automatic movement to move the tool guide to the offset position, - a cooperative manual movement to move the tool guide from the offset position to the insertion position.

[0010] The cooperative manual movement is servo-controlled to constrain the displacement of the tool guide on a plane orthogonal to the planned trajectory and passing through the pose insertion, such that the only possible movements of the tool guide during the cooperative manual movement are a translation along a principal axis of the tool guide and optionally a rotation around the axis of the planned trajectory, the speed of movement of the tool guide during the cooperative manual movement being determined as a function of an effort exerted by the practitioner on the tool guide, said effort being measured by the force sensor.

[0011] This specific sequence of movements allows the tool guide to be repositioned precisely and safely to re-engage a medical instrument already partially inserted into the patient's body (for example, after capturing control images). The automatic movement maintains the tool guide at a certain distance from the medical instrument to limit the risk of collision between the tool guide and the instrument. The final approach of the tool guide to re-engage the partially inserted medical instrument is performed by the user through a cooperative manual movement mode. The robot ensures accurate positioning along the planned trajectory axis. The axis of the tool guide is constrained during the cooperative manual movement.

[0012] In particular embodiments, the control unit is configured to determine an approach pose, and the automatic movement successively comprises: - a free automatic movement to move the tool guide to the approach position, - a predictable automatic movement to move the tool guide from the approach position to the offset position.

[0013] Decomposing the automatic movement into a free movement and a predictable movement provides added safety. Due to its repeatable nature, the user can intuitively anticipate the predictable automatic movement that will be performed between the approach position and the offset position. At the end of the free movement (when the tool guide is in the approach position), the practitioner can anticipate the predictable movement that will follow, and if they realize that an obstacle is preventing it, they can decide not to initiate it.

[0014] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in all technically possible combinations.

[0015] In particular embodiments, the predictable automatic movement comprises a linear movement contained in a plane comprising the planned trajectory and the approach pose.

[0016] In particular embodiments, the predictable automatic movement is a linear movement parallel to the planned trajectory.

[0017] In particular embodiments, the predictable automatic movement comprises a linear movement contained in a plane orthogonal to the axis of the planned trajectory and passing through the insertion pose.

[0018] In particular embodiments, during the cooperative manual movement, the speed of movement of the tool guide is determined as a function of a gain factor applied to the effort exerted by the practitioner, and the gain factor is also calculated as a function of the effort exerted by the practitioner.

[0019] In particular embodiments, the value of the gain factor is calculated as follows: [00201 gM=ax(i + 4^].«e,,, ; "s

[0021] where G(f) is the gain factor, K is a constant, Ifl is the effort exerted by the practitioner on the tool guide, Emin and Emax correspond respectively to a minimum value and a maximum value for the effort exerted by the practitioner.

[0022] In particular embodiments, the speed of movement of the tool guide is determined as a function of a distance between a current position of the tool guide and the insertion position.

[0023] In particular embodiments, the control unit is configured to prohibit any movement of the tool guide for at least a predetermined time when the insertion position is reached.

[0024] In particular embodiments, the robotic arm is an articulated arm having at least six degrees of freedom.

[0025] In particular embodiments, the insertion position and / or the planned trajectory is determined from a control medical image on which the partially inserted medical instrument 15 is visible.

[0026] In particular embodiments, the medical robot includes a user interface configured to provide information indicating whether the tool guide is correctly positioned to follow the planned trajectory

[0027] In particular embodiments, the medical robot includes a user interface configured to provide information indicating which movement, from a set of predefined movements, is currently in progress or ready to be triggered by a user command. The set of predefined movements includes free automatic movement, predictable automatic movement, and cooperative manual movement. Presentation of the figures

[0028] The invention will be better understood upon reading the following description, given by way of non-limiting example, and made with reference to Figures 1 to 14, which represent:

[0029] [Fig. 1] a schematic representation of an example of an embodiment of a medical robot according to the invention,

[0030] [Fig.2] a schematic representation of a trajectory that a medical instrument must follow from an entry point on the patient's skin to a target point in or near a treatment area in the patient's anatomy of interest,

[0031] [Fig.3] a schematic representation of an example of the embodiment of a robotic arm,

[0032] [Fig.4] a schematic representation of an example of an embodiment of a tool guide intended to be fixed to a distal end of the robotic arm,

[0033] [Fig.5] an illustration of the tool guide highlighting a device for holding a medical instrument at one end of the tool guide,

[0034] [Fig.6] an illustration of the tool guide highlighting the positioning of the medical instrument on the tool guide as well as markers detectable by a navigation system,

[0035] [Fig.7] an illustration of an example embodiment of the tool guide retention system,

[0036] [Fig.8] a schematic representation of the system for holding the system in a closed position,

[0037] [Fig.9] a schematic representation of the holding system in an open position,

[0038] [Fig. 10] an illustration of the determination of an insertion pose, an offset pose and an approach pose for the tool guide,

[0039] [Fig. 11] an illustration of the medical robot with the tool guide in the approach position,

[0040] [Fig. 12] an illustration of the medical robot with the tool guide in remote position,

[0041] [Fig. 13] an illustration of the medical robot with the tool guide at the insertion position,

[0042] [Fig. 14] an example of the implementation of a servo loop for a admittance control of cooperative manual movement of the tool guide.

[0043] In these figures, identical reference numerals from one figure to another designate identical or analogous elements. For clarity, the elements shown are not necessarily to the same scale, unless otherwise stated. Detailed description of the invention

[0044] Fig. 1 schematically represents an example of an embodiment of a medical robot 10. The medical robot 10 is used to assist a practitioner during a minimally invasive medical intervention on an anatomy of interest of a patient 20 positioned on an operating table 21. This type of intervention generally requires the insertion by the practitioner of one or more medical instruments 15 into the body of the patient 20.

[0045] As illustrated in [Fig.2], the medical instrument 15 is inserted into the patient's body 20 following a straight trajectory 41 from an entry point 43, located at the level of the patient's skin, to a certain depth to reach a target point 44 in or near a treatment area of ​​the anatomy of interest 45.

[0046] The procedure may, in particular, aim to remove or biopsy a tumor in an organ or bone, to treat a bone pathology (for example, by vertebroplasty or cementoplasty), or to stimulate a particular anatomical area. The anatomy of interest may correspond to an organ (for example, the liver, a lung, a kidney, or the brain) or to a bone (for example, a vertebra, a tibia, a femur, a hip, a pelvic bone, the pelvis, etc.). The medical instrument 15 may be a needle, an electrode, a probe, a drill, a trocar, a screw, etc.

[0047] In the example considered and illustrated in [Fig. 1], the medical robot 10 comprises a base 11. The base 11 of the medical robot 10 is equipped with motorized wheels, which allows the medical robot 10 to move in different directions by translational and / or rotational movements. The medical robot 10 further comprises a robotic arm 13, one end of which is connected to the base 11. At the other end of the robotic arm 13 is attached a tool guide 14 to guide the medical instrument 15. The medical robot 10 is thus used to position, hold, and guide the medical instrument 15; it acts as a third hand for the practitioner.

[0048] As illustrated in [Fig. 1], the medical robot 10 includes a control unit 12 configured to control the movement of the robotic arm 13 (and therefore of the tool guide 14 carried by the robotic arm 13). The control unit 12 includes at least one processor 122 and at least one memory 121 (magnetic hard drive, electronic memory, optical disk, etc.) in which a computer program product is stored, in the form of a set of program code instructions to be executed to implement the control of the robotic arm 13.

[0049] In the example considered, and as illustrated in [Fig. 3], the robotic arm 13 comprises six revolute joints 131 to 136 providing six degrees of freedom, allowing the medical instrument 15 to be positioned and / or moved in any pose in three-dimensional space. The revolute joint 136 corresponds to a rotation about a principal axis of the tool guide 14. Each joint includes an encoder for real-time measurement of its angular position. Advantageously, the joints of the robotic arm are not aligned and are offset from one another, which allows for better accessibility (a greater number of possible configurations of the robotic arm 13).

[0050] When the medical instrument 15 has axial symmetry for the part of the instrument intended to penetrate the patient's body (this is the case, for example, for a needle), five degrees of freedom are sufficient to guide and insert the medical instrument. The additional degree of freedom allows for redundancy and an infinite number of possible configurations of the robotic arm, enabling the tool guide to steer the medical instrument 15 along the desired trajectory 41. This redundancy is particularly useful for adapting to the patient's external contours or for ensuring the visibility of markers cooperating with a navigation system.

[0051] Figures 4 to 6 show an example of an embodiment of the tool guide 14. In the example considered, and as illustrated in [Fig. 4], the tool guide 14 is fixed to the robotic arm 13 by means of a flange 17. The tool guide 14 is coupled to a force sensor 16 to allow the control unit 12 to determine a force exerted on the tool guide 14. This force can, in particular, be exerted by the practitioner when manually moving the robotic arm 13. The term "practitioner" should be interpreted broadly: the medical robot can be operated by a surgeon, or by a medical operator acting under the supervision of a surgeon.

[0052] As illustrated in Figures 5 and 6, the tool guide 14 comprises a body 141 with a base 142 for attachment to the flange 17 by means of screws 143, and a retaining system 50 comprising two parts movable relative to each other. These two movable parts form a clamp enabling the retaining system 50 to hold the medical instrument 15 at the end of the body 141 of the tool guide 14 opposite the base 142. The two movable parts of the retaining system 50 can be actuated by a drive system such as a gear, a cam, a reverse-threaded screw, and / or a linear actuator, in order to lock or release the medical instrument 15. The tool guide 14 allows, for example, the guidance of medical instruments of different diameters. For example, such a guide can guide medical instruments with a diameter between 8 and 21 gauges (8 gauges corresponds to an external diameter of 4.191 mm; 21 gauges correspond to an external diameter of 0.812 mm). The holding system 50 defines a guide axis XX' orthogonal to a main axis ZZ' of the tool guide 14 (the main axis of the tool guide is in the direction from the base to the holding system 50).

[0053] Figures 7 to 9 illustrate an example of an embodiment of the tool guide 14 retaining system 50. This embodiment of the retaining system is similar to that described with reference to Figures 7 and 8 of patent application FR3094627A1. In this example, the tool guide 14 retaining system 50 comprises two jaws 51, 55. The jaws 51 and 55 can be moved between a closed position (as illustrated in [Fig. 8]) or an open position (as illustrated in [Fig. 9]). Each jaw has a groove 52, 56. The grooves 52, 56 extend transversely with respect to teeth 53, 57 arranged so as to interpenetrate when the retaining system 50 is in the closed position (each tooth 53, 57 has a segment of a grooves 52, 56). In the closed position, grooves 52 and 56 are adjacent and define a guide channel 59 to hold the medical instrument 15 and guide its translation. In the open position, grooves 52 and 56 are separated to position or release the medical instrument 15. The transition from the closed to the open position can be initiated by pressure from the practitioner on a lever 58 formed by a bearing surface of one of the jaws (jaw 55 in the example illustrated in Figures 11 to 13).

[0054] A navigation system (not shown in the figures) can be used to provide the control unit 12 of the medical robot 10 with information relating to a pose of the tool guide 14 or to a particular pose that the tool guide 14 must reach. In particular, an "insertion pose" is defined as the pose of the tool guide 14 in which it allows the medical instrument 15 to be guided along the desired trajectory 41 and to the exact depth to reach the target point 44 in the anatomy of interest 45. A pose of the tool guide is, for example, initially defined in a reference frame of the navigation system and then transformed into a pose in a reference frame of the medical robot 10 by the control unit 12.

[0055] In this application, the term "pose" should be understood as meaning "position and orientation". The pose of an object is defined with respect to a reference point corresponding to the origin of an orthonormal coordinate system (the reference point defines the position of the object and the orthonormal coordinate system defines the orientation of the object).

[0056] The "insertion position" corresponds to a position of the tool guide in which the tool guide 14 has a guide channel 59 that guides the medical instrument 15 along the axis of the planned trajectory 41 and to the exact depth to reach the target point 44. In [Fig. 1], the axis of the planned trajectory is represented by the axis TT'. In Figures 4, 5, and 7, the axis of the guide channel 59 of the tool guide 14 is represented by the axis XX'. In the insertion position, the guide axis XX' coincides with the axis TT' of the planned trajectory.

[0057] During insertion, the medical instrument 15 is guided in translation by the guide channel until it reaches a stop position (a portion of the medical instrument then abuts against the tool guide and prevents further insertion). The insertion position is defined such that when this stop position is reached, the distal end of the medical instrument 15 is at the target point 44. In the example illustrated in [Fig. 6], the tool guide 14 holds the medical instrument 15 in the holding system 50, and the medical instrument 15 is abutting the tool guide 14; this corresponds to the position of the medical instrument when it reaches the target point 44.

[0058] When the part of the medical instrument 15 intended to penetrate the patient's body has axial symmetry along the axis of the guide conduit, the different The tool guide 14 positions obtained by rotation around this axis correspond to the same insertion position. In this application, the expression "the positioning of the tool guide 14" must therefore be interpreted as corresponding to "the positioning of the guide conduit 59 of the tool guide 14".

[0059] The navigation system and the control unit 12 of the medical robot 10 can exchange data via communication means (wired or wireless). In the example considered, the navigation system is an optical navigation system (for example, an infrared stereoscopic camera). As illustrated in Figures 5 and 6, the tool guide 14 has studs 144 designed to accommodate optical markers 147. All the optical markers 147 present on the tool guide 14 correspond to a robot reference. The use of at least three optical markers makes it possible to define a plane and therefore a direct orthonormal three-dimensional reference frame. This allows the pose of the reference frame formed from the optical markers 147 that represent the tool guide 14 to be determined.

[0060] As illustrated in [Fig. 1], a patient reference 22 is placed on patient 20 near the anatomy of interest. In the example considered, the patient reference 22 also has at least three optical markers, so that the position of the patient reference 22 can be determined in the three spatial dimensions of the navigation system's reference frame.

[0061] The insertion position that the guide tool 14 must reach can be defined from the position of the patient reference 22. For this purpose, the patient reference 22 also includes radio-opaque markers that are visible on a medical image acquired by a medical imaging device (for example by computed tomography, magnetic resonance imaging, ultrasound, tomography, positron emission tomography, etc.).

[0062] As illustrated in [Fig.1], it is possible to plan the medical intervention from a pre-intervention medical image 40 acquired on the patient with the patient reference 22. This pre-intervention medical image 40 is stored in the memory 121 of the control unit 12. It is then possible for the control unit 12, from the pre-intervention medical image 40, to define the insertion position that the guide-tool 14 must take to guide the medical instrument 15 to perform the medical intervention. The planning of the medical intervention includes the determination, on the pre-intervention image 40, of the trajectory 41 to be followed by the medical instrument 15 (for example a needle) between the entry point 43 located at the level of the patient's skin 20 and the target point 44 located in or near the area to be treated (for example a tumor) in the anatomy of interest 45 (for example the liver).

[0063] The radiopaque elements of patient reference 22 are visible on the pre-intervention image 40. The placement of patient reference 22 can therefore be defined in The medical image. The planned trajectory 41 is also visible on the medical image. The insertion position of the guide-tool 14, which allows following trajectory 41, can then be defined relative to the patient reference position 22.

[0064] Using the navigation system 30, the medical robot 10 can determine the current position of the tool guide 14 and the position of the patient reference 22. Thanks to the pre-intervention image 40, the medical robot 10 knows the insertion position that the tool guide 14 must reach relative to the position of the patient reference 22. The control unit 12 can then be configured to automatically move the robotic arm 13 so that the tool guide 14 reaches the insertion position.

[0065] It is advantageous to verify, after partial insertion of the medical instrument, that the medical instrument is indeed following the planned trajectory 41 (it sometimes happens that the trajectory of the medical instrument is deviated when it pierces the patient's skin at the point of entry, or when it passes through a particular anatomical structure). To do this, it may be necessary to acquire one or more control medical images during insertion.

[0066] When the medical instrument 15 is inserted, it is held in place by the retention system 50 of the tool guide 14. Therefore, to acquire the control medical images, it is necessary to release the medical instrument from the guide. After acquiring the control images, it is necessary to reposition the medical instrument 15 in the retention system 50 of the tool guide 14.

[0067] To reposition the medical instrument 15 accurately and safely in the tool guide 14, the control unit 12 is configured to determine, from the planned trajectory 41, at least two specific positions of the tool guide 14: an insertion position and an offset position. The control unit 12 is also configured to implement a specific sequence of movements of the robotic arm 13 comprising successively: - an automatic movement to move the tool guide 14 to the offset position, - a cooperative manual movement to move the tool guide 14 from the offset position to the insertion position.

[0068] Advantageously, the control unit can be configured to determine a third specific pose, namely an approach pose, and the automatic movement can successively include: - a free automatic movement to move the tool guide 14 to the approach position, - a predictable automatic movement to move the tool guide 14 from the approach position to the offset position.

[0069] Figures 10 to 13 illustrate the three particular poses (the insertion pose 103, the offset position 102, and the approach position 101), as well as the successive movements allowing the tool guide 14 to reach the insertion position 103 from any initial position 100 by successively passing through the approach position 101 and the offset position 102.

[0070] In particular, [Fig. 10] illustrates the determination of the three specific poses (the insertion pose 103, the offset pose 102, and the approach pose 101). [Fig. 11] illustrates the free automatic movement of the tool guide 14 from any initial position 100 to the approach pose 101. [Fig. 12] illustrates the predictable automatic movement of the tool guide 14 from the approach pose 101 to the offset pose 102. [Fig. 13] illustrates the cooperative manual movement of the tool guide 14 from the offset pose 102 to the insertion pose 103.

[0071] As previously stated, the insertion pose 103 corresponds to a pose of the tool guide 14 in which the tool guide 14 has a guide channel 59 allowing the medical instrument 15 to be guided along the axis of the planned trajectory 41 and to the exact depth to reach the target point 44 (at the insertion pose, the XX' guide axis coincides with the TT' axis of the planned trajectory).

[0072] The insertion position 103 can be exactly the same as the initial insertion position used to perform the partial insertion of the medical instrument 15 before taking the control images. This is the case if the control images show that the medical instrument 15 is following the planned trajectory 41 correctly. However, the insertion position 103 can also correspond to a correction of the initial insertion position. This is the case, for example, if the control images show that the medical instrument 15 has deviated slightly from the initially planned trajectory, and it is necessary to slightly correct the planned trajectory to continue the procedure. The insertion position 103 corresponds to the position in which the guide tool 14 will re-engage the medical instrument 15, which is partially inserted into the patient's body.This is also the position in which the tool guide 14 allows the insertion of the medical instrument 15 to be finalized up to the target point (up to the stop position). As detailed previously, the insertion position 103 can be determined by the control unit 12 from a medical image on which the patient reference 22 is visible and on which the trajectory 41 can be defined.

[0073] The offset position 102 can be defined from the insertion position 103. As illustrated in [Fig. 10], the offset position 102 lies in a plane 104 orthogonal to the planned trajectory 41 and passing through the insertion position 103. The offset position 102 has the same orientation as the insertion position 103 (in other words, the guide channel 59 of the tool guide 14 is oriented along the same guide axis XX' for both the insertion position 103 and the offset position 102). The offset position 102 is defined to be sufficiently far from the insertion position 103 to avoid a collision between the The guide tool 14 and the medical instrument 15 move during the predictable automatic movement. The distance between the insertion position 103 and the offset position 102 is, for example, between 25 mm and 100 mm (between twenty-five and one hundred millimeters). In the example considered, the distance between the insertion position 103 and the offset position 102 is 50 mm (fifty millimeters).

[0074] The approach position 101 can be defined based on the offset position 102. In the example considered, and as illustrated in [Fig. 10], the approach position 101 is, for example, located on an axis 105 parallel to the planned trajectory 41 and passing through the offset position 102. The approach position 101 has the same orientation as the insertion position 103 and the offset position 102 (in other words, the guide channel 59 of the tool guide 14 is oriented along the same guide axis XX' at the insertion position 103, the offset position 102, and the approach position 101). Here again, the approach position 101 is defined to be sufficiently far from the medical instrument 15 and the patient 20 to avoid any risk of collision during the free automatic movement. The distance between the approach landing 101 and the offset landing 102 is, for example, between 25 mm and 100 mm. In the example considered, the distance between the approach landing 101 and the offset landing 102 is equal to 50 mm.

[0075] The term “automatic movement” means that the movement of the robotic arm 13 is performed autonomously by the medical robot 10, without intervention from the practitioner during the movement (the practitioner may initiate the movement, but does not intervene during the movement). This is the case for the free automatic movement that allows the tool guide 14 to be moved from any initial position 100 to the approach position 101 (see [Fig. 11]) and for the predictable automatic movement that allows the tool guide 14 to be moved from the approach position 101 to the offset position 102 (see [Fig. 12]).

[0076] The expression "predictable movement" means that the movement is repeatable. In particular, the movement of the tool guide 14 from the approach pose 101 to the offset pose 102 (as in [Fig. 12]) is always the same relative to these two poses. Conversely, the movement of the tool guide 14 from any initial pose 100 to the approach pose 101 (as in [Fig. 11]) is not necessarily predictable (it may consist of one or more elementary movements between the initial pose 100 and the approach pose 101 that may vary from one time to the next relative to these two poses).

[0077] By its repeatable aspect, the user can intuit the predictable automatic movement that will be carried out between the approach pose 101 and the offset pose 102. At the end of the free movement (when the tool guide is at the approach pose 101), the practitioner can imagine the predictable movement that will follow, and if he realizes that an obstacle prevents it, he can decide not to trigger it.

[0078] Advantageously, the predictable automatic movement can be defined such that the orientation of the guide axis XX' of the tool guide 14 is maintained throughout the movement of the tool guide 14 between the approach pose 101 and the offset pose 102.

[0079] The predictable automatic movement includes, for example, a linear movement contained within a plane comprising the planned trajectory 41 and the approach pose 101. In the example considered and illustrated in [Fig. 12], the predictable automatic movement is a linear movement parallel to the planned trajectory 41. During this movement, the guide axis XX' of the tool guide 14 remains parallel to the axis TT' of the planned trajectory 41. In this case, this corresponds to a "top-down" approach.

[0080] According to another example, the predictable automatic movement may include a linear movement contained in a plane orthogonal to the axis TT' of the planned trajectory 41, and passing through the insertion pose 103. In this case, this corresponds to a "side" approach.

[0081] The cooperative manual movement for moving the tool guide 14 from the offset position 102 to the insertion position 103 (see [Fig. 13]) is not an automatic movement. This movement is not performed entirely autonomously by the medical robot 10. In fact, this movement requires collaboration between the medical robot 10 and the practitioner.

[0082] In particular, the speed of movement of the tool guide 14 during the cooperative manual movement is controlled by the control unit 12 as a function of an effort exerted by the practitioner on the tool guide 14. The effort exerted by the practitioner is measured by the force sensor 16 (it corresponds to the resultant of the forces and torques applied at the level of the tool guide 14).

[0083] Furthermore, the cooperative manual movement is servo-controlled to constrain the displacement of the tool guide 14 on a plane 104 orthogonal to the planned trajectory 41 and passing through the insertion position 103 (see Figures 10 and 13). The only movements permitted for the tool guide 14 during the cooperative manual movement are a translation along the principal axis ZZ' of the tool guide 14 and optionally a rotation around the axis TT' of the planned trajectory 41 (in a first embodiment, only translation is permitted; in another embodiment, only translation and rotation are permitted).

[0084] Rotation around the TT' axis of the planned trajectory 41 can help avoid collisions, optimize the visibility of the tool guide markers 14 for the navigation system, or satisfy any other criterion at the practitioner's discretion during cooperative manual movement.

[0085] Figure 14 schematically represents an example of the implementation of a loop servo control for admittance control of cooperative manual movement of tool guide 14.

[0086] In the example considered and illustrated in Figure 14, the force measured by the force sensor 16 and the position of the tool guide 14 are input data for the servo loop. The servo loop is, for example, clocked at a frequency of 125 Hz. The servo loop provides as output a Cartesian velocity V4 == [ vy H'v Wy H'- ] of displacement of the tool guide 14. This servo loop includes the calculation of a velocity V\ corresponding to free cooperative manual guidance, to which constraints are applied (in particular a velocity control, a selection of allowed directions and a haptic law) to arrive at the velocity V4 to be applied to the tool guide to obtain a servo-controlled cooperative manual movement in the plane 104 orthogonal to the planned trajectory 41.

[0087] To obtain free cooperative manual guidance that would allow free movement in the six dimensions of space, the algorithm calculates a speed of movement for the robotic arm that cancels the force felt by the force sensor 16. In other words, the difference (also called the error) between the value of the force at a given instant (i.e., the force measured by the force sensor 16 at each iteration of the control loop) and the desired force value must tend towards zero. The algorithm's objective is to calculate a speed Vj that makes the error tend towards zero. For this, a PID controller (Proportional, Integral, Differentiator) is used. The error (i.e., the difference between the current force and the desired force) is the input to the PID controller, which outputs a speed V of the robotic arm 13 that allows the force error to tend towards zero.

[0088] The speed of the tool guide 14 is determined based on a gain factor applied to the force measured by the force sensor 16. When the practitioner exerts low-amplitude forces, jerky movements (tremors) are produced. To prevent the robotic arm 13 from reproducing these jerky movements, it is advantageous for the gain factor to also be calculated based on the force exerted by the practitioner. For this purpose, the PID controller has a constant proportional component and a variable proportional component. The values ​​of these two components are determined by a person skilled in the art and according to the equipment. The variable component varies proportionally with the force exerted by the practitioner on the robotic arm within a certain range of values ​​and with the constant proportional component.The forces due to the variable noise of the force sensor depending on its current position are not considered because taking these forces into account would lead to the robot moving even when no force is actually exerted by the practitioner. The value of the gain factor is, for example, calculated as follows:

[0089] [Math.l] 6( / ) = K x ( 1 + ) if E„„ < | / | s E,„ x

[0090] where G(f) is the gain factor, K is a constant, Ifl is the effort exerted by the practitioner on the tool guide (14), Emin and Emax correspond respectively to a minimum value and a maximum value for the effort exerted by the practitioner.

[0091] The velocity value Vi obtained at the output of the PID controller is then multiplied by a selection matrix. This selection matrix allows the allowed and prohibited directions to be chosen during movement. As a reminder, the only movements allowed for the tool guide 14 during the cooperative manual movement are a translation along the principal axis ZZ' of the tool guide 14 and optionally a rotation around the axis TT' of the planned trajectory 41. A velocity is then obtained. V2 = [0 0v, w^OO]

[0092] The speed V2 corresponds to a speed at the insertion pose position (w = [W H'~ ]T is the rotational component of the speed at the insertion position 103). It is necessary to transfer the speed V2 at the level of the tool guide 14, using a transfer matrix, according to the following formula:

[0093] [Math.2] Zîcly ' [o / 3] 2

[0094] where J3 is the 3x3 identity matrix, and dx is the position of the insertion pose 103 expressed in the reference frame of the tool guide 14. This product allows the linear speed of the tool guide 14 to be calculated due to the rotation around the insertion position which keeps the main axis ZZ' of the tool guide 14 aligned with the insertion position.

[0095] Haptic behavior rules can then be applied to the resulting velocity V3. In particular, it is advantageous for the movement speed of the tool guide 14 to be determined as a function of the distance between the current position of the tool guide 14 and the insertion position 103.

[0096] For example, for a constant effort by the practitioner, when the distance between the current position of the tool guide 14 and the insertion position 103 is less than a threshold, it is possible to consider decreasing the gain factor proportionally with the distance.

[0097] According to another example, when the distance between the current position of the tool guide 14 and the insertion position 103 is less than a threshold, an attractive spring behavior can be simulated by forcing the velocity to be proportional to the distance, independently of the effort exerted by the practitioner. For example, when the distance dz between the current position of the tool guide 14 and the insertion position 103 is less than 5 mm, the L- component of the velocity V3 can be defined by the formula:

[0098] [Math.3] vz = - k'dz

[0099] According to another example, when the distance between the current position of the tool guide and the insertion position is less than a threshold, the speed becomes constant (independently of the effort exerted by the practitioner, and independent of the distance between the current position of the tool guide and the insertion position).

[0100] It is also possible to configure the control unit 12 to prohibit any movement of the tool guide 14 for at least a predetermined time when the insertion pose 103 is reached (i.e. when the distance between the current pose of the tool guide 14 and the insertion pose 103 is small enough to consider that the insertion pose 103 is reached).

[0101] One or more of the rules cited above can be used to provide one or more haptic indications enabling the practitioner to feel the approach and attainment of the insertion pose 103. In particular, prohibiting any movement of the tool guide 14 for at least a predetermined time when the insertion pose 103 is reached provides the practitioner with a “virtual notch” effect.

[0102] The different movements of the robot arm 13 can be conditioned by the selection of a particular control mode on a user interface (for example on a touch display screen of the medical robot 10) and by the activation of the selected mode using a control pedal 19.

[0103] The control unit 12 can optionally be configured to automatically switch from one control mode to another at the end of a particular movement (for example, automatic switching to "predictable automatic mode" at the end of "free automatic mode," or automatic switching to "cooperative manual mode" at the end of "predictable automatic mode"). In this case, the user can simply activate the different movements successively using the foot pedal 19. The control unit 12 can be configured to automatically exit "cooperative manual mode" when the tool guide 14 reaches the insertion position 103.

[0104] The control unit 12 can be configured to display (for example, on a touchscreen display of the medical robot 10 or on an augmented reality headset connected to the medical robot 10) information on the position of the tool guide 14. In particular, the displayed information can indicate whether the position of the tool guide 14 cannot be verified (for example, if one or more optical markers 147 of the tool guide 14 are not visible to the navigation system). The displayed information can also indicate whether the tool guide has reached a particular position (approach position 101, offset position 102, or insertion position 103).

[0105] When the tool guide 14 has reached the insertion position 103, the practitioner can finalize the insertion of the medical instrument 15 into the anatomy of interest.

[0106] An example of implementation of the medical robot 10 will now be described.

[0107] Initially, at the practitioner's command, the control unit 12 of the medical robot 10 moves the robotic arm 13 to automatically position the tool guide 14 in an initial insertion pose. The initial insertion pose corresponds to a position of the tool guide 14 in which the tool guide 14 has a guide channel 59 allowing the medical instrument 15 to be guided along an initial trajectory planned on a pre-intervention medical image. The practitioner can then place the medical instrument 15 in the tool guide 14 and proceed with a partial insertion of the medical instrument 15 into the patient's body.

[0108] In a second step, the practitioner opens the tool guide clamp 14 to release the medical instrument 15. On command of the practitioner, the medical robot 10 goes into a cooperative manual release control mode to move the tool guide 14 away from the medical instrument.

[0109] In a third step, one or more control medical images are taken to verify that the partially inserted medical instrument 15 has not deviated from its planned trajectory. The operating table on which the patient is positioned may optionally be moved to take these control images, and then repositioned within the working area of ​​the medical robot 10.

[0110] If necessary, the insertion pose and / or the planned trajectory can be corrected using the control images (i.e., a new insertion pose different from the initial insertion pose and / or a new trajectory different from the initial trajectory can be determined). The actual position of the partially inserted medical device can be taken into account for calculating the insertion pose, which allows for precise repositioning of the medical device after a possible update of the planning data using the control images.

[0111] The production of the control image is thus facilitated and allows for the early detection and correction of any deviation of the medical instrument.

[0112] In a fourth step, the robotic arm 13 is controlled to move the tool guide 14 according to the specific sequence of movements proposed by the invention. This specific sequence of movements allows the tool guide 14 to re-engage the partially inserted medical instrument 15 accurately and safely. The sequence of movements comprises successively a free automatic movement to move the tool guide 14 to the approach position 101, a predictable automatic movement to move the tool guide 14 from the approach position 101 to the offset position 102, and a cooperative manual movement to move the tool guide 14 from the offset position 102 to the insertion position 103.

[0113] During cooperative manual movement, the displacement of the tool guide 14 is constrained on a plane orthogonal to the axis of the medical instrument 15 and the main axis The tool guide 14 is constrained in the direction of the medical instrument (it is only possible to move closer to or further away from the medical instrument and to rotate around it). When the tool guide 14 is at a certain distance from the medical instrument (for example, a distance less than or equal to 30 mm), the movement of the tool guide 14 is slowed to allow the practitioner to feel the approach of the insertion position and to limit the risk of collision between the tool guide and the medical instrument. The practitioner can then open the gripper of the tool guide 14 and continue to move the tool guide closer to the medical instrument. The constrained manual behavior is sufficiently stable and intuitive that the practitioner can move the tool guide with only one hand while keeping the gripper open. If the alignment is not perfect, the practitioner can adjust the position of the medical instrument using their other hand (the one not manipulating the tool guide).

[0114] Optionally, once the tool guide 14 is very close to the insertion point (for example, at a distance of 3 mm or less), its movement automatically stops at the insertion point, and the cooperative manual movement ceases. The practitioner can then release the forceps so that the medical instrument 15 is again held by the tool guide 14. The practitioner can then proceed with the insertion of the medical instrument 15 to the target point.

[0115] Throughout the procedure, the navigation system tracks the current position of the tool guide 14 and / or the patient reference 20. Information indicating whether the tool guide 14 is correctly positioned to follow the planned trajectory 41 can be provided via a user interface. This information can be visual (e.g., information displayed on a screen of the medical robot or on an augmented reality headset connected to the medical robot), auditory (e.g., via a sound or message spoken by a speaker of the medical robot 10), or haptic (e.g., via a vibration of the tool guide 14). The user interface can also indicate to the user which particular movement (free automatic movement, predictable automatic movement, or cooperative manual movement) is currently in progress or ready to be triggered by a user command (e.g., by pressing the pedal 19).In particular, at the end of the predictable automatic movement, the user interface can indicate to the practitioner that it is up to him to move the tool guide 14 to grasp the partially inserted medical instrument 15.

Claims

Demands

1. A medical robot (10) for assisting a practitioner during a minimally invasive medical procedure on an anatomy of interest (45) of a patient (20), the medical robot (10) comprises a robotic arm (13) the distal end of which is equipped with a tool guide (14) intended to guide the insertion of at least a part of a medical instrument (15) into the body of the patient (20) along a planned trajectory (41), said tool guide (14) being coupled to a force sensor (16), the medical robot (10) comprises a control unit (12) configured to control the robotic arm (13) in order to move the tool guide (14), characterized in that the control unit (12) is configured to determine, from the planned trajectory (41), an insertion position (103) and a remote position (102) of the tool guide (14),and to perform a sequence of movements of the robotic arm (13) comprising successively: - an automatic movement to move the tool guide (14) to the offset position (102), - a cooperative manual movement to move the tool guide (14) from the offset position (102) to the insertion position (103), the cooperative manual movement being controlled to constrain the movement of the tool guide (14) on a plane (104) orthogonal to the planned trajectory (41) and passing through the insertion position (103), such that the only possible movements of the tool guide (14) during the cooperative manual movement are a translation along a principal axis (ZZ') of the tool guide (14) and optionally a rotation around the axis (TT') of the planned trajectory (41), the speed of movement of the tool guide (14) during the cooperative manual movement being determined as a function of a force exerted by the practitioner on the tool guide (14),said force being measured by the force sensor (16).

2. A medical robot (10) according to claim 1 wherein the control unit (12) is configured to determine an approach pose (101), and the automatic movement successively comprises: - a free automatic movement to move the tool guide (14) to the approach position (101), - a predictable automatic movement to move the tool guide (14) from the approach position (101) to the offset position (102).

3. Medical robot (10) according to claim 2 wherein the predictable automatic movement comprises a linear movement contained in a plane comprising the planned trajectory (41) and the approach pose (101).

4. Medical robot (10) according to claim 3 wherein the predictable automatic movement is a linear movement parallel to the planned trajectory (41).

5. Medical robot (10) according to claim 2 wherein the predictable automatic movement comprises a linear movement contained in a plane orthogonal to the axis (TT') of the planned trajectory (41), and passing through the insertion pose (103).

6. Medical robot (10) according to any one of claims 1 to 5 wherein, during cooperative manual movement, the speed of movement of the tool guide (14) is determined as a function of a gain factor applied to the effort exerted by the practitioner, said gain factor also being calculated as a function of the effort exerted by the practitioner.

7. Medical robot (10) according to claim 6 wherein the value of the gain factor is calculated as follows: GM = K x ( 1 + ) if Emi„ < | / | i E,m where G(f) is the gain factor, K is a constant, Ifl is the force exerted by the practitioner on the tool guide (14), Emin and Emax correspond respectively to a minimum value and a maximum value for the force exerted by the practitioner.

8. Medical robot (10) according to any one of claims 1 to 7 wherein the speed of movement of the tool guide (14) is determined as a function of a distance between a current pose of the tool guide (14) and the insertion pose (103).

9. A medical robot (10) according to any one of claims 1 to 8 wherein the control unit (12) is configured to prohibit any movement of the tool guide (14) for at least a predetermined duration. completed when the insertion position (103) is reached.

10. Medical robot (10) according to any one of claims 1 to 9 wherein the robotic arm (13) is an articulated arm having at least six degrees of freedom.

11. Medical robot (10) according to any one of claims 1 to 10 wherein the insertion pose (103) and / or the planned trajectory (41) is determined from a medical control image on which the partially inserted medical instrument 15 is visible.

12. Medical robot (10) according to any one of claims 1 to 11 comprising a user interface configured to provide information indicating whether the tool guide (14) is correctly positioned to follow the planned trajectory (41).

13. Medical robot (10) according to any one of claims 1 to 12 comprising a user interface configured to provide information indicating which movement, from a set of predefined movements, is currently in progress or ready to be initiated by a user command, said set of predefined movements comprising free automatic movement, predictable automatic movement and cooperative manual movement.

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