WO2025087793A1 - Tool-changing system for robotic minimally invasive medical procedures - Google Patents

Abstract

The invention relates to a tool-changing system (50) for a robotic arm (13) of a medical robot. The tool-changing system comprises a fixed portion (60) intended to be positioned permanently at one end of the robotic arm, and a removable portion (70) comprising a tool (80) suitable for assisting a practitioner during a minimally invasive medical procedure. The removable portion can be replaced to change tools. The tool-changing system is configured such that, when the fixed portion (60) and the removable portion (70) are assembled with each other, a rotational movement of an actuation ring of the removable portion with respect to a locking pin of the fixed portion allows passage from an unlocked position to a locked position by the actuation ring pushing a locking element into a recess of the locking pin.

Description

Tool changing system for minimally invasive robotic medical interventions

Field of invention

The present application belongs to the field of robotic devices for assisting a practitioner during a medical intervention. More particularly, the application relates to a tool changing system for a robotic arm of a medical robot.

State of the art

In order to perform a minimally invasive medical intervention aimed at reaching a target anatomical area (for example to perform a biopsy or ablation of a tumor in an organ, to perform a vertebroplasty, a cementoplasty or to stimulate an anatomical area) in an anatomy of interest of a patient (for example a lung, a kidney, the liver, the brain, the tibia, the knee, a vertebra, etc.), an operator can be assisted by a medical robot comprising a robotic arm at the end of which is coupled a tool (for example a guide for a medical instrument such as a needle, an electrode, a probe, a trocar, etc.).

Advantageously, the tool can be coupled to the robotic arm via a tool changer allowing the tool to be changed during an intervention or between two interventions. Patent applications EP3939532A1, US20140066944A1, US20220409303A1 and CN114176737A give different examples of embodiments of a tool changer for a robotic arm of a medical robot.

It is important that the tool changer allows for quick and easy tool changes. In addition, the tool changer must allow for reliable tool mounting on the robotic arm. This means that the tool mounting is repeatable every time, and that it is not possible to unintentionally disassemble the tool. Also, the tool changer must limit errors introduced into the calculation of tool positioning during the medical procedure.

A sterile drape should generally be placed to isolate the robotic arm from the patient (the robotic arm is generally not sterilizable). The tool changer must then not compromise the sterility of the equipment used for the medical procedure. In addition, the positioning of the sterile drape should not cause any difficulty in mounting the tool on the robotic arm. Prior art tool changers do not provide an optimal guarantee of rapid, simple and reliable tool change with a sufficient level of sterility.

Description of the invention

The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above.

For this purpose, and according to a first aspect, the present invention provides a tool changing system for a robotic arm of a medical robot. The tool changing system comprises a fixed part intended to be permanently positioned at a distal end of the robotic arm and a removable part comprising a tool suitable for assisting a practitioner during a minimally invasive medical procedure. The removable part can be replaced to change the tool. The fixed part comprises:

- a chassis,

- a locking stud of generally cylindrical shape, the surface of which includes at least one recess,

- at least one positioning pin,

The removable part includes:

- a connecting piece comprising a tubular wall adapted to receive the locking stud, the tubular wall comprising at least one radial opening, the connecting piece comprising at least one orifice intended to cooperate with said at least one positioning pin,

- an actuating ring comprising at least one slope on its internal surface,

- at least one locking element housed at the level of said at least one radial opening between the internal surface of the actuating ring and the tubular wall of the connecting piece.

The tool changing system is configured such that, when the fixed part and the removable part are assembled with each other so that said at least one positioning pin is housed in said at least one orifice, a rotational movement of the actuating ring relative to the locking stud allows a passage from an unlocked position to a locked position by a push of the locking element by said at least one slope of the ring actuating, along a radial axis, in said at least one recess of the locking stud.

The tool changing system according to the invention allows simple and rapid mounting of a tool on the robotic arm. The system is designed to allow the user to assemble or disassemble a tool on the robotic arm by a simple rotational movement of the actuating ring.

Furthermore, the assembly is particularly reliable. Thanks to the irreversible geometry of the locking mechanism, the tool cannot be unintentionally detached from the robotic arm: only a rotational movement of the actuating ring around the locking pin allows the removable part to be detached.

In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in any technically possible combination.

In particular embodiments, the fixed part and the removable part each comprise at least one visual marker indicating the locked position or the unlocked position when the fixed part and the removable part are assembled with each other and said visual markers are opposite each other.

In particular embodiments, the tool and the actuating ring each comprise at least one optical marker.

In particular embodiments, the removable part comprises at least one NFC tag, and the fixed part comprises at least one NFC reader configured to receive information transmitted by said at least one NFC tag of the removable part when the fixed part and the removable part are assembled with each other and the actuating ring is in the locked position.

In particular embodiments, the tool comprises a device for guiding a medical instrument such as a needle, a probe, an electrode, a catheter, a screw, a drill or a trocar.

In particular embodiments, the tubular wall of the connecting piece of the removable part comprises at least one additional radial opening to promote sterilization of the removable part.

In particular embodiments, the tool changing system further comprises a sterile drape intended to cover at least the robotic arm of the medical robot. The sterile drape comprises a circular opening whose periphery is formed by a ring intended to enclose a shoulder of the frame of the fixed part. The shoulder is configured to be covered by the actuating ring when the fixed part and the removable part are assembled with each other, the ring being then held between the shoulder and the actuating ring.

Advantageously, the placement of the sterile drape at the tool change system does not add an additional interface that could cause difficulties in locking the system. Indeed, the placement of the sterile drape is done radially relative to the main axis of the tool change system. In this way, no interface is added at the contact plane between the fixed part and the removable part. This last point ensures better repeatability of mounting a tool on the robotic arm.

In particular embodiments, the sterile sheet comprises an NFC tag, the fixed part comprises an NFC reader configured to receive information transmitted by the NFC tag of the sterile sheet when the ring of the sterile sheet encloses the shoulder of the frame of the fixed part.

According to a second aspect, the present invention relates to a medical robot comprising a robotic arm and a tool changing system according to any of the preceding embodiments.

In particular embodiments, the medical robot comprises a control unit for the robotic arm, and the fixed part of the tool changing system comprises a display screen connected to the control unit and taking the form of a flexible strip wrapped around the frame of the fixed part.

In particular embodiments, the control unit is configured to display on the display screen an indication relating to the control of the robotic arm.

In particular embodiments, the tool and the actuating ring of the removable part of the tool changing system each comprise at least one optical marker, and the control unit is configured to:

- receive information from an optical navigation system relating to the positions of the optical markers of the tool and the actuation ring,

- check, based on the position information from the optical markers, whether the actuating ring is in the locked position.

In particular embodiments, the control unit is configured to check, depending on whether or not the information transmitted by the NFC tag of the sterile sheet is received, whether the sterile sheet is correctly positioned on the fixed part of the tool changing system.

In particular embodiments, the control unit is configured to check, based on the information transmitted by said at least one NFC tag of the removable part, whether the tool is suitable for a minimally invasive medical intervention. planned and stored by the control unit.

In particular embodiments, calibration data previously determined for different removable parts are stored in the control unit or are accessible by the control unit. The information transmitted by the NFC tag of the removable part comprises an identifier of the removable part. The control unit is configured to select, from said identifier, calibration data to be used to control the robotic arm.

Each removable part is measured and calibrated after assembly of the various parts. Thanks to this calibration, the system is free from positioning errors linked to the assembly of the parts of the removable part during its manufacture.

Presentation of figures

The invention will be better understood by reading the following description, given as a non-limiting example, and made with reference to figures 1 to 13 which represent:

[Fig. 1] a schematic representation of an example of the realization of a medical robot,

[Fig. 2] an exemplary embodiment of a tool changing system for the robotic arm of the medical robot shown in Figure 1,

[Fig. 3] an example of the realization of the fixed part of the tool change system shown in figure 2,

[Fig. 4] an example of the embodiment of the removable part of the tool changing system shown in figure 2,

[Fig. 5] another view of the embodiment of the removable part shown in Figure 4, highlighting the parts encircled by the actuating ring, [Fig. 6] a representation, according to a sectional view, of the removable part assembled on the fixed part in an unlocked position,

[Fig. 7] a representation, according to a sectional view, of the removable part assembled on the fixed part in a locked position,

[Fig. 8] a representation of the actuating ring in an unlocked position,

[Fig. 9] a representation of the actuating ring in a locked position, [Fig. 10] an illustration of the placement of a sterile drape at the fixed part of the tool changing system to cover the robotic arm,

[Fig. 11] a schematic representation of the placement of the sterile drape at the level of the fixed part of the tool change system,

[Fig. 12] a representation of the connecting piece of the removable part intended to receive the locking pin of the fixed part,

[Fig. 13] Another view of the connecting piece illustrated in Figure 12.

In these figures, identical references from one figure to another designate identical or similar elements. For reasons of clarity, the elements represented are not necessarily to the same scale, unless otherwise indicated.

Detailed description of an embodiment of the invention

Figure 1 schematically represents an exemplary 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 intervention table 21.

This type of intervention generally requires the practitioner to insert one or more medical instruments 15 into the patient's body 20 from an entry point located at the patient's skin to a certain depth to reach a target point in or near a region of the anatomy of interest to be treated.

The intervention may in particular aim to perform the ablation or biopsy of a tumor in an organ or in a 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 or a bone, for example the liver, a lung, a kidney, the brain, a vertebra, the tibia, the femur, the hip, the knee, the bones of the pelvis, the pelvis, etc. The medical instrument 15 may be a needle, an electrode, a probe, a drill, a trocar, a screw, etc.

In the example considered and illustrated in Figure 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 fixed a tool changing system 50. As will be detailed later, the tool changing system 50 comprises a removable part comprising a tool adapted to assist the practitioner during the minimally invasive intervention. This tool is for example intended to guide the medical instrument 15 (for example a needle, a probe, a electrode, or a trocar). The medical robot 10 thus plays the role of a third hand for the practitioner.

As illustrated in Figure 1, the medical robot 10 comprises a control unit 12 configured to control the movement of the robotic arm 13 (and therefore of the tool carried by the robotic arm 13). The control unit 12 comprises at least one processor 122 and at least one memory 121 (magnetic hard disk, 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.

In the example considered and illustrated in Figure 1, the robotic arm 13 comprises six rotoid joints 131 to 136 providing six degrees of freedom allowing the medical instrument 15 to be positioned and/or moved in any pose in the three-dimensional space (in the present application, the term “pose” must be understood as meaning “position and orientation”).

As illustrated in FIG. 1, a navigation system 30 may be used to provide the control unit 12 of the medical robot 10 with information relating to a current pose of the tool 80 and an insertion pose that the tool 80 must reach. The current pose and the insertion pose are for example initially defined in a reference frame of the navigation system 30 and then transformed into poses in a reference frame of the medical robot 10 by the control unit 12. The control unit 12 may then be configured to automatically move the robotic arm 13 so that it reaches the insertion pose. The insertion pose corresponds to a pose of the tool 80 at which it allows the medical instrument 15 to be guided along a planned trajectory and at the exact depth to reach the target point in the anatomy of interest.

The navigation system 30 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 30 is an optical navigation system. As illustrated in FIG. 4, the tool 80 comprises pads 82 intended to accommodate optical markers. All of the optical markers present on the tool 80 correspond to a robot reference 14. 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 thus makes it possible to determine the pose of the reference frame formed from the optical markers which represent the tool 80.

As illustrated in Figure 1, a patient reference 22 is placed on the patient 20 near the anatomy of interest. In the example considered, the patient reference 22 also comprises at least three optical markers, such that the pose of the patient reference 22 can be determined in the three spatial dimensions of the reference frame of the navigation system 30.

The insertion position that the tool 80 must reach can in particular be defined from the position of the patient reference 22. For this purpose, the patient reference 22 also includes radiopaque markers which are visible on a medical image acquired by a medical imaging device (for example by computed tomography, magnetic resonance, ultrasound, tomography, positron emission, etc.).

It is thus possible to plan the medical intervention from a pre-interventional medical image 40 acquired on the patient provided with the patient reference 22. This pre-interventional 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-interventional medical image 40, to define the insertion position that the tool 80 must take to guide the medical instrument 15 to carry out the medical intervention.

The planning comprises determining, on the pre-interventional image 40, the trajectory 41 to be followed by the medical instrument 15 (for example a needle) between an entry point 43 located at the skin of the patient 20 and a target point 44 located in or near a region to be treated (for example a tumor) in the anatomy of interest 45 (for example the liver) of the patient 20. The patient reference 22 (more precisely the radiopaque elements of the patient reference 22) is visible on the pre-interventional image 40. The pose of the patient reference 22 can therefore be defined in the medical image. The insertion pose of the tool 80 for following the trajectory 41 can then be defined relative to the pose of the patient reference 22.

Using the navigation system 30, the medical robot 10 can determine the pose of the tool 80 (or more precisely the pose of the robot reference 14) and the pose of the patient reference 22. Thanks to the pre-interventional image 40, the medical robot 10 knows the insertion pose that the tool 80 must reach in relation to the pose of the patient reference 22. The control unit 12 can then be configured to automatically move the robotic arm 13 so that it reaches the insertion pose.

It is important to be able to change tools easily, quickly and reliably during a medical procedure (for example, when several different medical instruments need to be inserted into the patient's body during a single procedure), or between two medical procedures. It is also important to ensure a sufficient level of sterility of the equipment used during a medical procedure. Figure 2 illustrates an exemplary embodiment of a tool changing system 50 for the robotic arm 13 of the medical robot 10 described above with reference to Figure 1. The tool changing system 50 comprises a fixed part 60 intended to be positioned permanently (i.e. permanently) at the distal end of the robotic arm 13, and a removable part 70 comprising a tool 80 adapted for the envisaged medical intervention. The removable part 70 can be replaced to change the tool.

Figure 3 represents an exemplary embodiment of the fixed part 60 of the tool changing system 50. The fixed part 60 comprises a chassis 61, preferably made of electrically insulating material, for example plastic, in order to allow electrical insulation with the tool 80 (or with the medical instrument 15 carried by the tool 80 if the tool is a guide).

The fixed part 60 also comprises a locking stud 62 of generally cylindrical shape, the surface of which comprises at least one recess 63 (for example a groove, a furrow, a groove or a hollow). The recess or recesses are arranged circumferentially on the cylindrical surface of the locking stud 62. In the example considered and illustrated in FIG. 3, the recess 63 corresponds to a groove which occupies the entire circumference of the locking stud 62. However, nothing would prevent, according to another exemplary embodiment, having several separate grooves along the circumference of the locking stud 62.

The fixed part 60 also comprises at least one positioning pin 64. As will be seen later, this positioning pin 64 serves as a reference for correctly assembling the removable part 70 on the fixed part 60. In the example considered and illustrated in FIG. 3, the fixed part 60 comprises two positioning pins 64 on the chassis 61.

The frame 61 serves as a support for the locking stud 62 and the positioning pin(s) 64.

Figures 4 and 5 represent an exemplary embodiment of the removable part 70 of the tool changing system 50.

In the example considered, and as illustrated in Figure 4, the removable part 70 comprises a tool 80 which comprises a guide device 81 with two parts movable relative to each other. The guide device 81 is intended to hold and guide the medical instrument 15 (for example a needle, a probe, an electrode, a catheter, a screw, a drill or a trocar) at the level of a clamp formed by the two movable parts. The two movable parts of the guide device 81 can be driven by a system such as a gear, a cam, a screw with reverse threads and/or linear actuator, in order to block or release the medical instrument 15. The tool 80 makes it possible, for example, to guide medical instruments of different diameters. For example, it makes it possible to guide medical instruments whose diameter is between 11 and 21 gauges. The guiding device 81 may in particular follow one of the embodiments described in patent application FR3094627A1.

As illustrated in Figure 5, the removable part 70 comprises a connecting piece 74 comprising a tubular wall 75 adapted to receive the locking stud 62 (in other words, the locking stud 62 is intended to be housed in the space formed inside the tubular wall 75 of the connecting piece 74 when the removable part 70 is assembled on the fixed part 60). The connecting piece 74 comprises at least one orifice 77 intended to cooperate with a positioning pin 64 of the fixed part 60. In the example considered and illustrated in Figure 5, the connecting piece 74 comprises two orifices 77 intended to receive the two positioning pins 64 of the fixed part 60. The tubular wall 75 also comprises one or more radial openings 76 arranged circumferentially around the tubular wall 75 of the connecting piece 74.

As illustrated in Figure 5, the removable part 70 also comprises an actuating ring 71 and at least one locking element 78 housed at a radial opening 76, between the internal surface of the actuating ring 71 and the tubular wall 75 of the connecting part 74. In the example considered and illustrated in Figure 5, there are three radial openings 76 and three locking elements 78 (only two are visible in the figure). Each locking element 78 takes the form of a ball. Each radial opening 78 takes the form of a circular opening whose diameter is smaller than that of the ball it accommodates, in order to prevent the ball from being able to pass through the opening.

The tool changing system 50 is configured so that, when the fixed part 60 and the removable part 70 are assembled with each other so that the positioning pins 64 are housed in their respective orifices 77, a rotational movement of the actuating ring 71 relative to the locking stud 62 allows a passage from an unlocked position to a locked position by a push of each locking element 78 by a slope of the internal surface of the actuating ring 71, along a radial axis, in the recess 63 of the locking stud 62 (the internal surface 72 of the actuating ring 71 and the slope 73 of the internal surface 72 are visible in FIGS. 8 and 9 which will be described later).

The recess 63 therefore has a shape suitable for accommodating the locking elements 78. In other words, the shape of the recess 63 allows the locking elements 78 to fit into the recess 63 when the fixed part 60 and the removable part 70 are assembled in the locked position. The fitting of each locking element 78 into the recess 63 makes it possible to maintain the tool changing system 50 in the locked position.

As stated previously, nothing would prevent, in a variant, arranging several distinct recesses 63 circumferentially on the cylindrical surface of the locking stud 62 (instead of a single recess along the entire circumference of the locking stud 62), such that each recess 63 is adapted to accommodate a locking element 78.

In the example considered and illustrated in the figures, a fraction of a turn (for example one sixth of a turn) of the actuating ring 71 in one direction allows the passage from the unlocked position to the locked position. A fraction of a turn of the actuating ring 71 in the opposite direction allows the passage from the locked position to the unlocked position.

Figures 6 to 9 illustrate the assembly of the removable part 70 with the fixed part 60, and the transition from the unlocked position to the locked position.

Figure 6 shows the assembly of the removable part 70 on the fixed part 60 in the unlocked position. It can be seen in particular in Figure 6 that the locking element 78 is not fitted into the recess 63 of the locking stud 62. In this position, the locking element 78 rests at the bottom of a slope 73 hollowed out in the internal surface 72 of the actuating ring 71.

Figure 8 shows the actuating ring 71 and the locking elements 78 in the unlocked position. It can be seen from this figure that, in the unlocked position, each locking element 78 rests at the bottom of a slope 73 cut into the inner surface 72 of the actuating ring 71.

Figure 7 shows the assembly of the removable part 70 on the fixed part 60 in a locked position. It can be seen in particular in Figure 7 that the locking element 78 is fitted into the recess 63 of the locking stud 62. In this position, the locking element 78 rests at the top of the slope 73 hollowed out in the internal surface 72 of the actuating ring 71.

Figure 9 shows the actuating ring 71 and the locking elements 78 in the locked position. It can be seen from this figure that, in the locked position, each locking element 78 rests at the top of a slope 73 cut into the inner surface 72 of the actuating ring 71.

When moving from the unlocked position (figures 6 and 8) to the locked (figures 7 and 9), the rotational movement of the actuating ring 71 relative to the locking stud 62 causes the locking elements 78 to be pushed by the slopes 73 of the internal surface 72 of the actuating ring 71, along a radial axis, towards the recess 63 of the locking stud 62, through the radial openings 76. The locking elements 78 then fit into the recess 63 and maintain the tool changing system 50 in the locked position. Only a reverse rotational movement of the actuating ring 71 can then allow the passage from the unlocked position to the locked position. During this reverse rotational movement, the locking elements 78 move away from the recess 63 by reaching the bottom of the slopes 73, thus allowing the fixed part 60 and the removable part 70 to be separated.

The inclination of the slopes 73 is preferably very small (less than a few degrees of angle, for example less than 5° degrees) in order to ensure the irreversibility constraint of the system. An irreversible mechanism is a system that can be actuated only by a single component, called a driving member. In the case of the tool changing system 50 according to the invention, the driving member is the actuating ring 71. Each ball (locking element 78) moves in contact with the slope 73 during a rotational movement of the actuating ring 71. These balls cannot under any circumstances open the mechanism by applying a force to the balls other than that caused by a rotational movement of the actuating ring 71. This phenomenon ensures that the tool changing system 50 cannot open during an intervention, without the activation of the actuating ring 71.

In particular embodiments, and as illustrated in FIG. 3, the fixed part 60 of the tool changing system 50 comprises a display screen 66 connected to the control unit 12. The display screen 66 takes, for example, the form of a flexible strip wrapped around the frame 61 of the fixed part 60. The control unit 12 can then be configured to display on the display screen 66 an indication relating to the control of the robotic arm 13 (for example to indicate whether the robotic arm 13 is moving, whether the tool 80 has reached the insertion position, whether the tool 80 is approaching an obstacle or is in contact with an obstacle, and/or whether an urgent action must be carried out by the practitioner). The display screen 66 thus allows the practitioner to have feedback on the intervention in progress without having to look away from the operating field.

To detect whether the tool 80 is approaching an obstacle, the tool changing system 50 may include a distance sensor, such as a ultrasonic sensor or a retro-reflective photoelectric sensor. To detect whether the tool 80 is in contact with an obstacle, the tool changing system 50 may include a force sensor 68 (see Figure 3). When the tool 80 encounters an obstacle, the force sensor 68 detects a discontinuity in the perceived forces and moments.

As illustrated in Figure 2, the fixed part 60 and the removable part 70 may each comprise at least one visual marker 65a, 65b indicating the locked position or the unlocked position when the fixed part 60 and the removable part 70 are assembled with each other and said visual markers 65a, 65b are opposite each other. For example, the assembly ring 71 of the removable part 70 comprises a visual marker 65b taking the form of an arrow and the fixed part 60 comprises a first visual marker 65a taking the form of an open padlock and a second visual marker taking the form of a closed padlock. When the fixed part 60 and the removable part 70 are assembled with each other, with the positioning pins 64 housed in their respective holes 77, if the arrow points to the open padlock, this means that the tool changing system 50 is in the unlocked position (the removable part 70 can then be freely removed from the fixed part 60), and if the arrow points to the closed padlock, this means that the tool changing system 50 is in the locked position (the removable part 70 cannot then be removed from the fixed part 60 without performing a rotational movement on the actuating ring 71).

It may be advantageous to automatically detect whether the tool changing system 50 is in the locked position. For this purpose, the actuating ring 71 may include an optical reference formed by one or more optical markers similar to those of the tool 80. The navigation system 30 may then allow the control unit 12 of the medical robot 10 to determine the position of the actuating ring 71 relative to the position of the tool 80, and to deduce therefrom whether the tool changing system 50 is in the locked position or not. Advantageously, an indication of whether the tool changing system 50 is in the locked position or not may be displayed on the display screen 66.

In particular embodiments, the removable part 70 comprises an NFC tag, and the fixed part 60 comprises an NFC reader configured to receive information transmitted by the NFC tag of the removable part 70 when the fixed part 60 and the removable part 70 are assembled with each other and the actuating ring 71 is in the locked position. The term “NFC” corresponds to the English acronym for “Near Field Communication”, in French “communication near-field communication”. This is a short-range (in the order of centimeters) and high-frequency wireless communication technology.

The control unit 12 can then be configured to check, based on the information transmitted by the NFC tag of the removable part 70, whether the tool changing system 50 is in the locked position or not. Indeed, for the NFC reader to be able to receive information from the NFC tag, the reader and the tag must be facing each other (they must be sufficiently close to each other). The reader and the tag can be arranged such that when the NFC tag of the removable part 70 is facing the NFC reader of the fixed part 60, this means that the tool changing system 50 is in the locked position. Thus, when the NFC reader receives information from the NFC tag, this means that the removable part 70 is correctly assembled to the fixed part 60 in the locked position. This offers another way to automatically detect whether the tool changing system 50 is in the locked position. Again, an indication of whether the tool changing system 50 is locked or not can be displayed on the display screen 66.

It is also possible to use two NFC readers at the fixed part 60 and one NFC tag at the removable part 70. The readers and the NFC tag can be arranged such that when the NFC tag of the removable part 70 is opposite a first NFC reader of the fixed part 60 this means that the tool changing system 50 is in the unlocked position, and when the NFC tag of the removable part 70 is opposite a second NFC reader of the fixed part 60 this means that the tool changing system 50 is in the locked position.

It is also possible to use two NFC tags at the removable part 70 and an NFC reader at the fixed part 60. The tags and the NFC reader can be arranged such that when a first NFC tag of the removable part 70 is opposite the NFC reader of the fixed part 60 this means that the tool changing system 50 is in the unlocked position, and when a second NFC tag of the removable part 70 is opposite the NFC reader of the fixed part 60 this means that the tool changing system 50 is in the locked position.

The control unit 12 can also be configured to check, based on the information transmitted by the NFC tag of the removable part 70, whether the tool 80 is suitable for the minimally invasive medical intervention planned and stored by the control unit 12. The information transmitted by the NFC tag of the removable part 70 can in fact correspond to an identifier of the tool 80 carried by the removable part 70, and the control unit 12 can store data associating for each identifier tool one or more types of intervention that can be implemented with the corresponding tool.

In particular embodiments, calibration data previously determined for different removable parts are stored in the control unit 12 (or are accessible by the control unit 12, for example via communication with a data server). If the information transmitted by the NFC tag of the removable part 70 comprises an identifier of the removable part 70, the control unit 12 can be configured to select, from said identifier, calibration data to be used to control the robotic arm 13.

Advantageously, the various parts of the removable part 70 (in particular the actuating ring 71, the connecting part 74, the locking elements 78 and the tool 80) are assembled by the manufacturer and cannot be disassembled by the user. This allows calibration of the entire removable part 70 to ensure better accuracy of the entire component. The calibration consists of the metrological measurement, using a three-dimensional measuring machine (CMM), of the functional geometries of the component formed by the removable part 70. For example, the calibration consists of measuring:

- of the contact plane 85 between the fixed part 60 and the removable part 70 (see figure 11),

- from the hole 77 housing the positioning pin 64,

- of the axis of the medical instrument 15 intended to be guided by the guiding device 81,

- a mechanical stop allowing the medical instrument 15 to stop in translation during its insertion.

With the knowledge of this unique calibration data for each component, the position of each of the parts is transparent in the positioning of the assembly through the robotic arm 13. In other words, all the interfaces between the different elements of the component do not generate a positioning error, because the component (i.e. the set of parts forming the component) is measured after assembly. The positioning error of the medical instrument 15 is then limited to:

- the accuracy of the calibration measurement,

- the error linked to the repeatability of the assembly of the removable part 70 on the fixed part 60,

- the error linked to the repeatability of the positioning of the medical instrument in the guiding device 80. Conversely, if the component (the removable part 70) was not calibrated as a whole, then the manufacturing precision of each of the parts would have to be taken into account in the overall positioning error of the medical instrument 15.

As previously indicated, the tool changing system 50 must not compromise the sterility of the equipment used for the medical intervention. It is advantageous to use a sterile sheet to cover the robotic arm 13 or even the entire medical robot 10. The removable part 70 is sterilized before each intervention.

To facilitate the assembly of the removable part 70 with the fixed part 60 despite the presence of the sterile sheet, it is advantageous to use a sterile sheet specially adapted to the tool changing system 50. For this purpose, and as illustrated in FIG. 10, the tool changing system 50 may comprise a sterile sheet 90 which has a circular opening whose periphery is formed by a ring 91 intended to grip a shoulder 67 of the frame 61 of the fixed part 60. The ring 91 may be made of a rigid material in order to be forcefully positioned on the shoulder 67. Alternatively, the ring 91 may be made of an elastic material to facilitate its positioning on the shoulder 67. Advantageously, the shoulder 67 is configured to be covered by the actuating ring 71 when the fixed part 60 and the removable part 70 are assembled with each other. The ring 91 is then held between the shoulder 67 and the actuating ring 71 (the ring 91 is sandwiched between the shoulder 67 and the actuating ring 71). The ring 91 may also include a positioning element (groove, pin, flat) intended to cooperate with the shoulder 67 to prevent the ring 91 from rotating around the shoulder 67 once the sterile drape is positioned.

With such arrangements, an operator does not have to touch a non-sterile part of the robotic arm 10 when assembling the removable part 70 or when removing the removable part 70 to install another in order to change the tool 80.

Since the ring 91 is held between the shoulder 67 and the actuating ring 71, the risk of the sterile drape 90 moving from its attachment point during a movement of the robotic arm 13 is limited. In other words, once assembled, the sterile drape can no longer be moved or reveal a non-sterile part.

Furthermore, the circular opening in the sterile drape 90 makes it possible to prevent the sterile drape from obstructing the assembly of the fixed part 60 with the removable part 70. As can be seen in Figure 11, when positioning the sterile drape 90, no interface is added at the contact plane 85 between the fixed part 60 and the removable part 70 (in particular, the sterile drape 90 does not come into contact with the fixed part 60). house at the level of this contact plane 85). This makes it possible to guarantee better repeatability of assembly of the removable part 70 on the fixed part 60 of the tool change system 50.

In particular embodiments, the sterile drape 90 comprises an NFC tag, and the fixed part 60 comprises an NFC reader configured to receive information transmitted by the NFC tag of the sterile drape 90 when the ring 91 of the sterile drape encloses the shoulder 67 of the frame 61 of the fixed part 60.

The control unit 12 can then be configured to check, depending on whether or not the information transmitted by the NFC tag of the sterile sheet 90 is received, whether the sterile sheet 90 is correctly positioned on the fixed part 60 of the tool changing system 50.

Indeed, for the NFC reader to be able to receive information from the NFC tag, the reader and the tag must be facing each other (they must be sufficiently close to each other). The reader and the tag can be arranged in such a way that when the NFC tag of the sterile drape 90 is facing the NFC reader of the fixed part 60, this means that the sterile drape 90 is correctly positioned on the fixed part 60 of the tool changing system 50.

The NFC reader used to read information from the NFC tag of the sterile drape may correspond to the same NFC reader as that used to read information from a tag of the removable part 70 of the tool changing system 50. Alternatively, different NFC readers may be used.

Advantageously, the information transmitted by the NFC tag of the sterile sheet 90 may include an identifier (for example a serial number) of the sterile sheet 90. It then becomes possible to automate the traceability of the material (sterile sheet 90 and/or tool 80) used during the medical intervention and the management of the stocks of the hospital in which the intervention takes place.

As illustrated in Figures 5, 12 and 13, to promote the sterilization of the removable part 70, the tubular wall 75 of the connecting piece 74 of the removable part 70 may comprise one or more additional radial openings 79. These additional radial openings 79 are not associated with locking elements 78. The presence of the additional radial openings 79 has the objective of allowing the passage of a sterilizing product (fluid) into the space which separates the tubular wall 75 of the connecting piece 74 and the internal surface 72 of the actuating ring 71.

Furthermore, the base of the connecting piece 74 is designed with particular geometric shapes 86 in order to limit the interface surface between this base and the actuating ring 71 when fixing the connecting piece 74 on the actuating ring 71. Again, this helps to promote sterilization of the removable part 70. This in fact optimizes access and flow of the sterilizing product on the actuating ring 71. Indeed, the autoclave is a hot steam bath and it is important not, particularly during drying, for the steam to remain trapped in the mechanism. This can cause condensation of the fluid and form a pocket of liquid inside the system (a liquid that cannot escape quickly turns into stagnant water and is therefore unsuitable for medical use).

Claims

Claims 1. Tool changing system (50) for a robotic arm (13) of a medical robot (10), the tool changing system (50) comprising a fixed part (60) intended to be permanently positioned at a distal end of the robotic arm (13) and a removable part (70) comprising a tool (80) adapted to assist a practitioner during a minimally invasive medical intervention, the removable part (70) being able to be replaced to change the tool, the tool changing system (50) being characterized in that the fixed part (60) comprises: - a chassis (61), - a locking stud (62) of generally cylindrical shape, the surface of which comprises at least one recess (63), - at least one positioning pin (64), the removable part (70) comprises: - a connecting piece (74) comprising a tubular wall (75) adapted to receive the locking stud (62), the tubular wall (75) comprising at least one radial opening (76), the connecting piece (74) comprising at least one orifice (77) intended to cooperate with said at least one positioning pin (64), - an actuating ring (71) comprising at least one slope (73) on its internal surface (72), - at least one locking element (78) housed at said at least one radial opening (76) between the internal surface (72) of the actuating ring (71) and the tubular wall (75) of the connecting piece (74), the tool changing system (50) is configured so that, when the fixed part (60) and the removable part (70) are assembled with each other so that said at least one positioning pin (64) is housed in said at least one orifice (77), a rotational movement of the actuating ring (71) relative to the locking stud (62) allows a passage from an unlocked position to a locked position by a thrust of the locking element (78) by said at least one slope (73) of the actuating ring (71), along a radial axis, in said at least one recess (63) of the locking stud (62). 2. Tool changing system (50) according to claim 1 wherein the fixed part (60) and the removable part (70) each comprise at least one visual marker (65a, 65b) indicating the locked position or the unlocked position. when the fixed part (60) and the removable part (70) are assembled with each other and said visual markers (65a, 65b) are opposite each other. 3. Tool changing system (50) according to one of claims 1 to 2 in which the tool (80) and the actuating ring (71) each comprise at least one optical marker. 4. Tool changing system (50) according to one of claims 1 to 3 in which the removable part (70) comprises at least one NFC tag, and the fixed part (60) comprises at least one NFC reader configured to receive information transmitted by said at least one NFC tag of the removable part (70) when the fixed part (60) and the removable part (70) are assembled with each other and the actuating ring (71) is in the locked position. 5. Tool changing system (50) according to one of claims 1 to 4 in which the tool (80) comprises a guiding device (81) for a medical instrument (15) such as a needle, a probe, an electrode, a catheter, a screw, a drill or a trocar. 6. Tool changing system (50) according to one of claims 1 to 5 in which the tubular wall (75) of the connecting part (74) of the removable part (70) comprises at least one additional radial opening (79) to promote sterilization of the removable part (70). 7. Tool changing system (50) according to one of claims 1 to 6, further comprising a sterile sheet (90) intended to cover at least the robotic arm (13) of the medical robot (10), the sterile sheet (90) comprising a circular opening whose periphery is formed by a ring (91) intended to enclose a shoulder (67) of the frame (61) of the fixed part (60), said shoulder (67) being configured to be covered by the actuating ring (71) when the fixed part (60) and the removable part (70) are assembled with each other, the ring (91) then being held between the shoulder (67) and the actuating ring (71). 8. Tool changing system (50) according to claim 7 wherein the sterile sheet (90) comprises an NFC tag, the fixed part (60) comprises an NFC reader configured to receive information transmitted by the NFC tag of the sterile sheet (90) when the ring (91) of the sterile sheet encloses the shoulder (67) of the frame (61) of the fixed part (60). 9. Medical robot (10) comprising a robotic arm (13) and a tool changing system (50) according to any one of claims 1 to 8. 10. Medical robot (10) according to claim 9 comprising a control unit (12) of the robotic arm (13), and in which the fixed part (60) of the tool changing system (50) comprises a display screen (66) connected to the control unit (12) and taking the form of a flexible strip wrapped around the frame (61) of the fixed part (60). 11. Medical robot (10) according to claim 10 wherein the control unit (12) is configured to display on the display screen (66) an indication relating to the control of the robotic arm (13). 12. Medical robot (10) according to any one of claims 9 to 11, in which the tool (80) and the actuating ring (71) of the removable part (70) of the tool changing system (50) each comprise at least one optical marker, and in which the control unit (12) is configured to: - receive information from an optical navigation system (30) relating to the positions of the optical markers of the tool (80) and of the actuating ring (71), - check, based on the position information of the optical markers, whether the actuating ring (71) is in the locked position. 13. Medical robot (10) according to claim 9, in which the tool changing system (50) is according to claim 8, and the control unit (12) is configured to check, depending on whether or not the information transmitted by the NFC tag of the sterile sheet (90) is received, whether the sterile sheet (90) is correctly positioned on the fixed part (60) of the tool changing system (50). 14. Medical robot (10) according to claim 9, wherein the tool changing system (50) is according to claim 4, and the control unit (12) is configured to check, based on the information transmitted by said at least an NFC tag of the removable part (70), if the tool (80) is suitable for a minimally invasive medical intervention planned and stored by the control unit (12). 15. Medical robot (10) according to claim 9, wherein the tool changing system (50) is according to claim 4, calibration data previously determined for different removable parts are stored in the control unit (12) or are accessible by the control unit (12), the information transmitted by the NFC tag of the removable part (70) comprises an identifier of the removable part (70), and the control unit (12) is configured to select, from said identifier, calibration data to be used to control the robotic arm (13).