Cooperative medical robot for ensuring insertion of medical device

Abstract

The invention relates to a medical robot (10) for assisting a physician during a medical intervention. The medical robot comprises a robot arm (13) provided at one end with a tool guide (14) for guiding a medical instrument (15) along a planned trajectory. The medical robot (10) comprises a control unit (12) configured to control the movement of the robotic arm (13). A'co-axial control 'mode allows the tool guide (14) to move along the axis of the planned trajectory from an insertion position to a patient body (20) and then back to the insertion position. This makes it possible to partially insert the medical instrument (15) when the tool guide is close to the patient, and then complete the insertion of the medical instrument when the tool guide is in the inserted position. This prevents the medical device from bending at the beginning of insertion.

Description

Technical Field

[0001] The present application relates to the field of robotic devices for assisting doctors during medical interventions. More specifically, the present application relates to a medical robot comprising a robotic arm equipped with a tool guide for holding, guiding and releasing a medical device during a minimally invasive medical intervention. Background Art

[0002] Minimally invasive or percutaneous medical interventions may require a doctor to insert one or more medical devices (such as needles, probes, catheters, etc.) into a patient's body to a certain depth to reach a target point within a target anatomical structure (such as a tumor in the liver, lung, kidney or bone).

[0003] When the process of inserting a medical device is performed entirely by a doctor, the outcome of the intervention depends to a large extent on the doctor's skills. With the aid of a remotely controlled medical robot, the precision of the process can be improved. Here, the success of the intervention still depends partly on the doctor's skills and may require continuous acquisition of medical images of the patient, which involves subjecting the patient to a high dose of radiation.

[0004] To further improve the precision of the insertion process and limit the radiation dose to which the patient is subjected, an automatically controlled robotic arm can be used. For example, the doctor indicates on pre-interventional medical images the trajectory that the medical device must follow, which starts from the entry point at the patient's skin level until it reaches the target point within the patient's target anatomical structure. The robotic arm can be equipped with a tool guide for guiding the medical device along an axis corresponding to the planned trajectory. Then, the robotic arm can be controlled to automatically select the insertion position (placement and orientation) at which the tool guide allows the medical device to be guided along the planned trajectory until it reaches the target point within the target anatomical structure.

[0005] When the robotic arm is in the insertion position, the tool guide is typically located at a considerable distance from the patient's skin (several centimeters or ten centimeters or more, etc.). This distance depends on the length of the medical device and the depth at which the medical device is inserted into the patient's body (the insertion depth corresponds to the distance between the entry point at the skin level and the target point). Then, when the medical device penetrates the patient's skin at the entry point, it deviates from the planned trajectory. This is because medical devices generally have a certain flexibility, and the greater the distance between the tool guide and the entry point during insertion, the greater the risk of the medical device deviating from the planned trajectory.

[0006] The deviation (curvature) problem of medical devices is known, and one of the most common solutions to solve this problem is to calculate the deviation from the planned trajectory (for example, see paragraphs

[0188] to

[0190] of patent application US2022 / 0265355A1). For example, mathematical models can be used to determine the potential bending or distortion of medical devices (depending on their length, diameter, material used, etc.). Due to the accuracy error of deviation estimation, this solution is not ideal.

[0007] Another solution is to check whether the instrument deviates from the trajectory after insertion and correct the positioning of the instrument accordingly if necessary. This solution is also not ideal because it may require additional medical images to be taken (the patient is exposed to more radiation), and the medical device needs to be inserted into the patient's body multiple times (lengthening the duration of the intervention). In addition, in the case of percutaneous ablation of tumors, this solution may also increase the risk of tumor spread.

[0008] International patent application WO2022 / 195210A1 describes a medical robot with a robotic arm provided with a tool guide. The medical robot is configured to control the movement of the robotic arm in a collaborative mode, in which the movement speed of the tool guide is determined as the force applied by the doctor on the tool guide changes. The movement of the tool guide can also be restricted in a specific direction. However, the document does not solve the problem of deviation of medical devices when inserted into the patient's body.

[0009] Patent application US2016 / 242849A9 describes a medical robot that includes a robotic arm provided with an actuator coupled to the distal end of the arm. The actuator can include a surgical instrument.

[0010] Patent application US2019 / 282301A1 describes an image-based guidance system that can define the trajectory of a needle by setting the positions of the insertion point and the target point. Summary of the Invention

[0011] The object of the present application is to make up for all or part of the deficiencies of the prior art, especially the deficiencies mentioned above, by proposing a solution that can more reliably ensure the insertion angle and insertion depth of medical devices during minimally invasive interventions.

[0012] To this end, according to a first aspect, a medical robot is proposed for assisting a doctor during a minimally invasive medical intervention on a target anatomical structure of a patient. The medical robot includes a robotic arm, and a tool guide is provided at the distal end of the robotic arm. The tool guide is configured to guide the insertion of at least a part of a medical device into the patient's body along a planned straight-line trajectory between an entry point located at the patient's skin level and a target point located within the target anatomical structure. The medical robot includes a control unit configured to control the robotic arm to move the tool guide. The control unit is configured to determine and store an insertion position according to the planned trajectory. In the "automatic control" mode, the control unit is configured to automatically move the tool guide to the insertion position. In the "coaxial control" mode, the control unit is configured to determine the force exerted by the doctor on the tool guide by means of a force sensor coupled to the tool guide, and to move the tool guide as the determined force changes. In the coaxial control mode, the movement of the tool guide is restricted so as to only adopt:

[0013] - allowing translational movement of the tool guide along the axis of the planned trajectory, or

[0014] - allowing translational movement of the tool guide along the axis of the planned trajectory, and rotational movement of the tool guide about the axis of the planned trajectory.

[0015] In the coaxial control mode, the control unit is configured to provide haptic feedback to the doctor when the tool guide returns to the insertion position.

[0016] In the present application, the term "position" should be understood as "placement and orientation". The "insertion position" corresponds to the position of the tool guide at which the tool guide has a guide tube for guiding the medical device along the axis of the planned trajectory and to the exact depth required to reach the target point. During insertion, the medical device is translated by being guided by the guide tube until it reaches a stop position (then a part of the medical device starts to abut against the tool guide and prevents further insertion). The insertion position is defined such that when the stop position is reached, the distal end of the part of the device penetrating the patient's body is located at the target point. When the part of the medical device intended to penetrate the patient's body has axial symmetry along the axis of the guide tube, different positions of the tool guide obtained by rotating about this axis correspond to the same insertion position.

[0017] The coaxial control mode allows the tool guide to move from the insertion position to a position as close as possible to the patient's skin at the entry point while maintaining the axis of the planned trajectory. Then, when the tool guide is as close as possible to the patient's skin, the medical device can be placed in the tool guide and partially inserted into the patient to avoid bending and deviation of the medical device from the planned trajectory. Then, the coaxial control mode and haptic feedback allow the tool guide to be precisely repositioned to the insertion position (with the medical device still partially inserted). Once the tool guide is repositioned to the insertion position, the insertion of the medical device can be completed at the stop position to reach the target point.

[0018] When repositioning the tool guide to the insertion position in the coaxial control mode, with the medical device in place, the robotic arm or the doctor may potentially obstruct the line of sight of the optical navigation system used to determine the position of the tool guide. Since the insertion position has been previously recorded in the reference frame of the medical robot, the medical robot can automatically reposition the tool guide to the insertion position without using the optical navigation system.

[0019] Haptic feedback allows the doctor to sense the exact moment of reaching the insertion position. Optionally, haptic feedback can also allow the doctor to sense the approach to the insertion position. This makes it easy and intuitive to return to the insertion position. When the tool guide reaches the insertion position, haptic feedback gives the user a feeling of a virtual incision.

[0020] In a specific embodiment, the present invention may also include one or more of the following features alone or in any technically possible combination.

[0021] In a specific embodiment, in the coaxial control mode, when the distance between the current position of the tool guide and the insertion position is less than a first threshold, the control unit is configured to calculate the moving speed of the tool guide, and the moving speed varies with a gain factor applied to the force exerted by the doctor on the tool guide, and the value of the gain factor gradually decreases as the distance between the current position and the insertion position changes.

[0022] The decrease in the moving speed of the tool guide enables the doctor to sense the approach to the insertion position.

[0023] In a specific embodiment, in the coaxial control mode, when the distance between the current position of the tool guide and the insertion position is less than a second threshold, regardless of the force exerted by the doctor on the tool guide, the control unit is configured to limit or maintain the moving speed of the tool guide at a predetermined speed.

[0024] In a specific embodiment, in the coaxial control mode, the control unit is configured to prohibit any movement of the tool guide when the insertion position is reached, within a predetermined time period.

[0025] The sudden stop of the movement of the tool guide enables the doctor to sense the exact moment of reaching the insertion position.

[0026] Specifically, the insertion position can be determined with the aid of a navigation system (such as an optical navigation system) and pre-interventional medical images. Thus, in a specific embodiment, the tool guide includes at least one marker that can be detected by the navigation system, and the control unit is configured to:

[0027] - Receive a first information item related to the position of the tool guide in the reference frame of the navigation system from the navigation system,

[0028] - Receive a second information item related to the insertion position that the tool guide must adopt in the reference frame of the navigation system from the navigation system, in order to guide the medical device along the planned trajectory until the target point is reached,

[0029] - Determine the insertion position in the reference frame of the medical robot based on the first information item and the second information item.

[0030] In a specific embodiment, the second information item corresponds to the position of a patient reference in the reference frame of the navigation system, the patient reference being for placement on the patient to approach the target anatomical structure. The patient reference includes at least one marker and at least one radiopaque marker that can be detected by the navigation system. The control unit is configured to determine the insertion position based on the position of the patient reference and the planned trajectory. The planned trajectory is defined with the aid of pre-interventional medical images and relative to the position of the patient reference, and the target anatomical structure of the patient and the at least one radiopaque marker of the patient reference can be seen on the pre-interventional medical images.

[0031] In a specific embodiment, the part of the medical device for penetrating the patient's body has axial symmetry along an axis, and during the insertion of the medical device, the axis corresponds to the axis of the planned trajectory. In the coaxial control mode, the movement of the tool guide is restricted to translational movement of the tool guide along the axis of the planned trajectory and rotational movement of the tool guide around the axis of the planned trajectory.

[0032] With such an arrangement, when the instrument rotates about the axis of symmetry, the part of the instrument for penetrating the patient's body does not change. In such a case, the coaxial control mode can operate with translation and rotation about the axis of the trajectory. This makes it possible to modify the position of the tool guide without modifying the axis of the trajectory (the axis of the trajectory coincides with the axis of the guide tube, and the guide tube remains unchanged during the rotation of the tool guide about this axis).

[0033] When the tool guide approaches the patient's skin, the rotation control mode allows the position of the tool guide to be modified while keeping the guide tube along the axis of the trajectory. For example, this can avoid the tool guide colliding with an obstacle (such as the patient or a mark on the patient's body). At the insertion position, the rotation control allows the position of the tool guide to be modified without changing the insertion position (since the guide tube remains unchanged, any rotation of the tool guide about the axis of the trajectory corresponds to the same insertion position). This particularly helps to provide the doctor with a free available workspace.

[0034] In a specific embodiment, the tool guide includes two jaws. Each jaw includes a groove. The jaws can be driven between a closed position and an open position. In the closed position, the grooves are continuous and define a guide tube for holding the medical device and guiding the medical device for translation. In the open position, the grooves are spaced apart from each other to place or release the medical device. The guide tube adopts a position coaxial with the planned trajectory at the insertion position. The doctor can achieve a change from the closed position to the open position by pressing a lever formed by the support surface of one of the jaws. In the coaxial control mode, the control unit is configured to transfer the force applied by the doctor on the tool guide at a virtual application point, and the virtual application point is positioned such that the axis of the pressure applied on the lever forms an angle less than 20 degrees with the axis passing through the actual application point and the virtual application point of the pressure.

[0035] When the tool guide is as close as possible to the patient's skin, the doctor presses the lever to open the jaws in order to place the medical device in position. Then, the doctor releases the lever so that the tool guide continues to partially insert the medical device while holding the medical device. Before bringing the tool guide to the insertion position to complete the insertion of the medical device, the doctor presses the lever again to open the jaws of the tool guide.

[0036] In the control law, the specific position of the force application point is such that when the doctor presses the lever to open the jaws of the tool guide, untimely rotation of the tool guide can be avoided, and then the tool guide can be repositioned to the insertion position. This allows for an intuitive switch from translational control to rotational control: pressing the lever does not cause the tool guide to rotate; on the contrary, pressure applied on another part of the tool guide causes the tool guide to rotate.

[0037] In a specific embodiment, the robotic arm has at least six degrees of freedom.

[0038] Using at least six degrees of freedom advantageously enables the tool guide to be positioned at any location in three-dimensional space. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be better understood by reading the following description given as a non-limiting example and with reference to the following drawings:

[0040] Figure 1 shows a schematic diagram of an embodiment of a medical robot according to the present invention,

[0041] Figure 2 shows a schematic diagram of the trajectory followed by a medical device from the entry point at the patient's skin level to the target point within or near the treatment area within the patient's target anatomical structure,

[0042] Figure 3 shows Figure 1 a schematic diagram of the robotic arm of the medical robot shown,

[0043] Figure 4 shows Figure 3 a schematic diagram of a tool guide connected to the distal end of the robotic arm shown,

[0044] Figure 5 shows Figure 3 a detailed schematic of the tool guide shown,

[0045] Figure 6 shows another representation of the tool guide when holding a medical device,

[0046] Figure 7 shows a schematic diagram of an embodiment of a patient reference,

[0047] Figure 8 shows a schematic diagram of a coaxial control mode with the tool guide in the insertion position,

[0048] Figure 9 shows a schematic diagram of a coaxial control mode in which the tool guide has been translated axially along the axis of the planned trajectory from the insertion position to approach the entry point, thereby allowing partial insertion of the medical device,

[0049] Figure 10 shows a schematic diagram of a coaxial control mode in which the tool guide has been repositioned to the insertion position to complete the insertion of the medical device until it reaches the target point,

[0050] Figure 11 ​​​​​​​​​​​shows a schematic view of an embodiment of a retention system for a tool guide

[0051] Figure 12 shows a schematic view of a force being applied to one of the jaws of the retention system in Figure 11 to move it to the open position

[0052] Figure 13 shows a schematic view of a force being applied to one of the jaws of the retention system in Figure 11 to hold it in the open position

[0053] Figure 14 shows a schematic illustration of a specific implementation example where, with a constant force applied by a doctor on the tool guide, the movement speed of the tool guide varies as a function of the distance between the current position of the tool guide and the insertion position

[0054] In these figures, the same reference numerals from one figure to another denote the same or similar elements. For clarity, unless otherwise stated, the elements shown are not necessarily to the same scale DETAILED DESCRIPTION OF THE INVENTION

[0056] Figure 1 shows a schematic view of an example of an embodiment of a medical robot 10 according to the present invention. The medical robot 10 is used to assist a doctor during a minimally invasive medical intervention on a target anatomical structure of a patient 20 on an intervention table 21

[0057] This type of intervention typically requires the doctor to insert one or more medical devices 15 from an entry point at the patient's skin level into the patient 20's body to a certain depth to reach a target point within or near the area of the target anatomical structure to be treated

[0058] Specifically, the purpose of the intervention can be to ablate or biopsy a tumor in an organ or bone, treat a bone pathology (e.g., by vertebroplasty or kyphoplasty), or stimulate a specific anatomical area. The target anatomical structure can correspond to an organ or bone, such as the liver, lung, kidney, brain, spine, tibia, femur, hip joint, knee, pelvic bones, pelvis, etc. The medical device 15 can be a needle, electrode, probe, drill, trocar, screw, etc

[0059] Figure 2 shows the straight trajectory 41 that the medical device 15 needs to follow, i.e., starting from the entry point 43 at the patient 20's skin level, to the target point 44 within or near the treatment area within the patient 20's target anatomical structure 45

[0060] In Figure 1 ​​​In the illustrated example, the medical robot 10 includes a base 11. The base 11 of the medical robot 10 is equipped with electric wheels, which allow the medical robot 10 to move in different directions by translation and / or rotation.

[0061] The medical robot 10 further includes a robotic arm 13, one end of which is connected to the base 11. The other end of the robotic arm 13 is connected to a tool guide 14, which is used to guide a medical device 15 (such as a needle, a probe, an electrode or a trocar).

[0062] The medical robot 10 is used to assist a doctor in positioning, holding the position of the medical device 15 or guiding the medical device 15 during a medical intervention. In this way, the medical robot 10 can act as a third hand of the doctor.

[0063] As Figure 1 illustrated, the medical robot 10 includes a control unit 12, which is configured to control the movement of the robotic arm 13 (and thus control the tool guide 14). The control unit 12 includes at least one processor 122 and at least one memory 121 (magnetic hard disk, electronic memory, optical disc, etc.), and a computer program product is stored in the memory 121 in the form of a set of program code instructions to be executed to implement different steps of a method for positioning the robotic arm 13, particularly the tool guide 14.

[0064] The robotic arm 13 is also as Figure 3 illustrated. In Figure 1 and Figure 3 the illustrated example, the robotic arm 13 includes six rotary joints 131 - 136, which provide six degrees of freedom, such that the medical device 15 can be placed and / or moved to any position in three-dimensional space. Advantageously, the joints 131 - 135 of the robotic arm 13 are not aligned and are offset relative to each other, which gives the robotic arm 13 more possible configurations. Each joint includes at least one encoder, such that its angular position can be known in real time. Then, the configuration of the robotic arm 13 corresponds to the set of parameter values taken by the joints 131 - 136 (such as the rotation angle values of each joint). The rotary joint 136 corresponds to the rotation about the main axis of the tool guide 14.

[0065] It should be noted that when the part of the medical device 15 used to penetrate the patient's body has axial symmetry, it is not necessary to be able to rotate about the axis of symmetry (in such a case, five degrees of freedom are actually sufficient to guide and position the medical device). This additional degree of freedom allows the robotic arm 13 to be in a redundant situation for a given position of the tool guide 14, and to have an infinite number of possible configurations. This redundant situation is particularly useful for adapting to constraints related to the patient 20 positioning or the operating room configuration.

[0066] As Figure 3 and Figure 4 shown, the tool guide 14 is connected to the robotic arm 13 via a flange 17. The tool guide has a spindle 145, which is shown in dashed lines in Figure 4 . The tool guide 14 is coupled to a force sensor 16 to allow the control unit 12 to determine the force applied to the tool guide. When the robotic arm 13 is manually moved, this force can be applied, specifically, by a doctor.

[0067] As Figure 5 and Figure 6 shown, the tool guide 14 includes a body 141 and a holding system 50; the body 141 has a base 142 for connection to the flange 17 using screws 143, and the holding system 50 includes two parts that are movable relative to each other. The holding system 50 is used to hold the medical device 15 at the end of the body 141 of the tool guide 14 opposite the base 142. The two movable parts of the holding system 50 can be driven by a drive system (such as gears, cams, screws with reverse threads, and / or linear actuators) to block or release the medical device 15. The tool guide 14 enables, for example, guiding medical devices of different diameters. For example, such a guide can guide medical devices with diameters between 11 gauge and 21 gauge. Gauge is a unit of measurement commonly used to define the outer diameter of medical devices such as needles, probes, or catheters (11 gauge corresponds to an outer diameter of 2.946 mm; 21 gauge corresponds to an outer diameter of 0.812 mm).

[0068] As Figure 1 shown, a navigation system 30 can be used to provide the control unit 12 of the medical robot 10 with information related to the current position of the tool guide 14 and the insertion position that the tool guide needs to reach. The current position and the insertion position are initially defined, for example, in the reference frame of the navigation system 30 and then converted by the control unit 12 to positions in the reference frame of the medical robot 10. Then, the control unit 12 can be configured (in a so-called "automatic control" mode, without doctor intervention) to automatically move the robotic arm 13 so that the robotic arm 13 reaches the insertion position. The navigation system 30 and the control unit 12 of the medical robot 10 can exchange data via a communication device (wired or wireless).

[0069] The insertion position corresponds to the position of the tool guide 14 at which the tool guide 14 can guide the medical device 15 along the axis of the planned trajectory 41 to an exact depth in order to reach the target point 44 within the target anatomical structure 45. The holding system 50 of the tool guide 14 forms, for example, a guide tube through which at least a part of the medical device 15 will slide during the insertion of the medical device 15 into the body of the patient 20. At the insertion position, the axis of the trajectory 41 coincides with the axis of the guide tube.

[0070] The insertion position is defined as varying with the length of the medical device 15 and the insertion depth corresponding to the planned trajectory 41. During insertion, the medical device is translated under the guidance of the guide tube until it reaches a stop position (whereupon a part of the medical device starts to abut against the tool guide, preventing any further insertion). The insertion position is defined such that, when this stop position is reached, the distal end of the part of the device penetrating the patient's body is located at the target point.

[0071] When the part of the medical device used to penetrate the patient's body has axial symmetry along the guide tube (i.e., along the planned trajectory), different positions of the tool guide obtained by rotation about this axis correspond to the same insertion position (in other words, when the tool guide 14 is in the position for inserting the medical device 15, the insertion position corresponds to the position adopted by the guide tube formed by the holding system 50 of the tool guide 14).

[0072] In the example considered, the navigation system 30 is an optical navigation system. The navigation system 30 includes at least two optical sensors 31, for example, two sensors corresponding to a stereo camera operating in the infrared radiation range or the visible light range.

[0073] As Figure 5 and Figure 6 shown, the tool guide 14 includes a stub 144 for receiving an optical marker 147. Advantageously, the tool guide 14 includes at least three optical markers 147 so that the position of the tool guide can be determined in three spatial dimensions of the reference frame of the navigation system 30. The navigation system 30 and / or the control unit 12 know a priori the respective positions of the optical markers 147 of the tool guide relative to each other. Advantageously, the geometry of each optical marker 147 can also be known a priori. In Figure 6 the example shown, the shape of the optical marker 147 is spherical.

[0074] As Figure 6As shown, the tool guide 14 holds the medical device 15 in the holding system 50, and the medical device 15 abuts against the tool guide 4 (which corresponds to the position when the medical device reaches the target point 44).

[0075] The optical marker 147 can be passive or active. A passive optical marker reflects light radiation emitted by another element (such as the navigation system 30). For example, a passive optical marker can correspond to a reflective sphere detectable by an infrared stereo camera (e.g., manufactured by Northern Digital Inc., used in the navigation system), or a black-and-white pattern visible to the stereo camera (e.g., used in the navigation system of ClaroNav). An active optical marker itself emits light radiation detectable by the navigation system 30, such as infrared radiation.

[0076] As Figure 1 shown, all the markers 147 present on the tool guide 14 correspond to the robot reference 18.

[0077] Using at least three optical markers 147 can define a plane, thereby defining a direct orthogonal three-dimensional reference system with a z-axis perpendicular to the plane and x and y axes on the plane, such that the reference system is direct. Thus, the position of the reference system formed by the optical markers 147 representing the tool guide 14 can be determined. The three axes x, y, and z can define six degrees of freedom, namely translation along the x, y, or z axis and rotation about these axes. However, it should be noted that a single optical marker with a three-dimensional characteristic geometry can be used instead of a set of spherical optical markers 147.

[0078] As Figure 1 shown, the patient reference 22 is placed on the patient 20 and close to the target anatomical structure. Figure 7 A schematic diagram of the patient reference 22 is shown. The patient reference 22 includes at least three optical markers 221, such that the position of the patient reference 22 can be determined in three spatial dimensions of the reference system of the navigation system 30. The respective positions of the optical markers 221 of the patient reference 22 relative to each other are known a priori by the navigation system 30 and / or the control unit 12. Advantageously, the geometry of each optical marker 221 can also be known a priori. In Figure 7In the illustrated example, the patient reference 22 includes three spherical optical markers 221. The spherical shape can optimize the reflection of light radiation. The above description regarding the optical markers 147 of the active or passive type of the tool guide 14 also applies to the optical markers 221 of the patient reference 22. Here, it is also conceivable to use a single optical marker with a three-dimensional characteristic geometry instead of the three spherical optical markers 221.

[0079] In the remainder of this description, by way of non-limiting example, the optical sensor 31 of the navigation system 30 and the various optical markers 147, 221 are considered to be designed to operate with infrared light radiation. The optical markers 147, 221 are further considered to be passive markers. The optical sensor 31 of the navigation system 30 is configured to emit infrared radiation. This infrared radiation is reflected by the various optical markers 147, 221 towards the optical sensor 31. The optical sensor 31 is configured to receive the reflected infrared radiation. Then, the navigation system 30 can determine the distance between the optical markers 147, 221 and the optical sensor 31 by measuring the time taken for the infrared light to travel to and fro between the optical sensor 31 and the optical markers 147, 221. By knowing the distance between each optical marker 147, 221 and each optical sensor 31, and by knowing a priori the relative arrangement of the optical markers 147, 221 on the tool guide 14 and the patient reference 22 with respect to each other, the position of the tool guide 14 and the patient reference 22 in the reference frame of the navigation system 30 can be determined.

[0080] Specifically, the insertion position that the tool guide 14 needs to reach can be defined according to the position of the patient reference 22. For this purpose, as Figure 7 shown, the patient reference 22 further includes radiation-impermeable markers 222 that are visible on medical images acquired by a medical imaging device (such as by computed tomography, magnetic resonance, ultrasound, tomography, positron emission, etc.). The navigation system 30 and / or the control unit 12 knows a priori the respective positions of the radiation-impermeable markers 222 with respect to each other. Advantageously, the geometry of the radiation-impermeable markers 222 can also be known a priori. Preferably, the patient reference 22 includes at least three radiation-impermeable markers 222. For example, the radiation-impermeable markers 222 can be ceramic beads. However, it should be noted that a single radiation-impermeable marker with a three-dimensional characteristic geometry can be used instead of the three spherical radiation-impermeable markers 222.

[0081] Thus, a medical intervention can be planned based on pre-interventional medical images 40 (which can in particular be three-dimensional images) obtained on a patient with the patient reference 22. The pre-interventional medical images 40 are stored in the memory 121 of the control unit 12. Then, the control unit 12 can define the insertion position that the tool guide 14 needs to adopt based on the pre-interventional medical images 40 in order to guide the medical device 15 for a medical intervention. Then, the insertion position can be stored by the control unit 12.

[0082] The planning includes determining, on the pre-interventional image 40, the entry point 43 of the medical device 15 (such as a needle) at the level of the patient 20's skin and the trajectory 41 to be followed between a target point 44 in or near a treatment area (such as a tumor) within the target anatomical structure 45 (such as the liver) of the patient 20. The patient reference 22 (more precisely, the radiopaque element 222 of the patient reference 22) is visible on the pre-interventional image 40. Thus, the position of the patient reference 22 can be defined in the medical image. Then, relative to the position of the patient reference 22, the insertion position of the tool guide 14 for following the trajectory 41 can be defined.

[0083] The entry point 43, the target point 44 and the patient reference 22 can be determined automatically (such as using an automatic segmentation algorithm), semi-automatically (with the help of a doctor) or manually by a doctor on the image.

[0084] It should be noted that the trajectory can also be determined on preoperative images obtained a few days before the intervention (images obtained without providing the patient reference to the patient). Then, the preoperative images can be registered with the pre-interventional images 40, where the patient reference 22 is visible on the pre-interventional images, to obtain the relative position of the patient reference 22 with respect to the trajectory, and thus the relative position of the patient reference 22 with respect to the insertion position of the tool guide 14.

[0085] In the example considered, the navigation system 30 is configured to provide the control unit 12 of the medical robot 10 with the current position of the tool guide 14 in the reference frame of the navigation system 30 (or more precisely, the position of the robot reference 18). However, the control unit 12 of the medical robot 10 knows the current position of the tool guide 14 in the reference frame of the medical robot 10 (through the encoders of the joints 131 - 136). The control unit 12 can thus determine the transformation to be performed to define the position in the reference frame of the medical robot 10 based on the position in the reference frame of the navigation system 30.

[0086] The navigation system 30 is also configured to provide the control unit 12 of the medical robot with the position of the patient reference 22 in the reference frame of the navigation system 30. Then, the control unit 12 can define the position of the patient reference 22 in the reference frame of the medical robot 10. Now, with the pre-intervention image 40, the control unit 12 of the medical robot 10 knows the insertion position that the tool guide 14 needs to reach relative to the position of the patient reference 22. Therefore, the control unit 12 can determine the insertion position that the tool guide 14 needs to reach in the reference frame of the medical robot based on the information provided by the navigation system 30. Then, the control unit 12 can be configured to automatically move (in the so-called "automatic control" mode) the robotic arm 13 so that the robotic arm 13 reaches the insertion position.

[0087] For example, the movement of the robotic arm 13 is adjusted by selecting a control mode on the user interface of the medical robot 10 and activating the selected mode by the control pedal 19.

[0088] The automatic control mode corresponds to the mode in which the robotic arm 13 is completely controlled by the control unit 12. Then, the robotic arm 13 moves automatically without doctor intervention.

[0089] In the so-called "cooperative control" mode, the control unit 12 is configured to use the force sensor 16 to determine the force applied by the doctor on the tool guide 14 and move the tool guide according to the determined force. This corresponds to the mode in which the doctor can manually move the robotic arm 13 by himself, but the movement of the robotic arm 13 is controlled by the control unit 12 (for example, to limit the movement speed and / or possible movement directions of the robotic arm 13). There can be multiple "cooperative control" modes.

[0090] For example, the "cooperative approach control" mode corresponds to the mode in which the doctor moves the robotic arm 13 to bring the tool guide 14 closer to the patient, so that the robotic arm 13 enters the field of view of the optical navigation system 30. In this mode, it makes sense to control the movement speed of the robotic arm 13 as the force applied by the doctor on the robotic arm 13 changes. In this mode, the robotic arm 13 is usually allowed to move in all directions. Then, the robotic arm can move automatically (in the automatic control mode) to the insertion position.

[0091] The "coaxial control" mode corresponds to the mode in which the doctor can manually move the robotic arm 13, but only in such a way that when the medical device 15 slides in the tool guide 14, the position of the tool guide 14 can be kept on the planned trajectory 41, that is to say, in such a way that the axis of the guide tube formed by the holding system 50 of the tool guide 14 is kept consistent with the axis of the planned trajectory 41.

[0092] In other words, in the coaxial control mode, the control unit 12 is configured to prohibit any movement that may cause a change in the position of the tool guide 14, and such a movement makes it no longer follow the trajectory 41 when the medical device 15 slides in the tool guide.

[0093] In a specific embodiment, the movement of the tool guide 14 in coaxial control is restricted to only allow a movement that enables the tool guide 14 to translate along the axis of the planned trajectory 41.

[0094] In the coaxial control mode, the control unit 12 is configured to provide haptic feedback to the doctor when the tool guide 14 returns to the insertion position. Such an arrangement can make it easy and intuitive to return to the insertion position.

[0095] Figures 8 - 10 Shows the coaxial control mode, in which the tool guide 14 translates close to the body of the patient 20 so as to partially insert the medical device 15 into the patient's body, and then the tool guide 14 is returned to the insertion position. In Figure 8 In, the tool guide is in the insertion position. In Figure 9 In, the tool guide 14 has translated along the axis of the planned trajectory 41 so as to be closer to the patient's body at the entry point 43 and as close as possible to the patient's skin 20. As Figure 9 As shown, then, the medical device 15 can be placed in the tool guide 14 and partially inserted into the body of the patient 20 when the tool guide 14 is as close as possible to the patient's skin, so as to avoid the medical device 15 bending and deviating from the planned trajectory 41. The coaxial control mode and the haptic feedback can accurately reposition the tool guide 14 to the insertion position (then the medical device is still partially inserted). Figure 10 Shows the situation where the tool guide 14 is repositioned to the insertion position. Once the tool guide 14 is repositioned to the insertion position, the insertion of the medical device 15 can be completed to reach the target point 44.

[0096] It is possible that the line of sight between the navigation system 30 and the reference (patient reference 22 or robotic reference 18) is blocked, which may impede obtaining information related to the reference position. Specifically, when the tool guide 14 is repositioned to the insertion position in the coaxial control mode, the medical device 15 is in place and may potentially block the line of sight between the navigation system 30 and the robotic reference 18. The recorded insertion position (in the reference frame of the medical robot) enables the tool guide 14 to be repositioned to the insertion position without using the navigation system 30.

[0097] In another specific embodiment, the movement of the tool guide 14 in coaxial control is restricted to permit not only translational movement of the tool guide 14 along the axis of the planned trajectory 41 but also rotational movement of the tool guide 14 about the axis of the planned trajectory 41 (any other movement of the tool guide is prohibited). In fact, when the part of the medical device 15 for penetrating the body of the patient 20 has axial symmetry along the axis of the trajectory 41, both the translation and the rotation about the axis of the trajectory 41 that the coaxial control mode can perform are advantageous. Thus, when the tool guide 14 approaches the skin of the patient 20, the rotational control enables the position of the tool guide to be modified while keeping the guide tube along the axis of the trajectory 41 (the axis of the trajectory coincides with the axis of the guide tube and the guide tube remains unchanged during rotation of the tool guide 14 about this axis). This makes it possible, for example, to avoid collision of the tool guide 14 with an obstacle (such as the patient reference 22 or the actual patient 20). At the insertion position, the rotational control mode enables the position of the tool guide 14 to be modified without modifying the insertion position (any rotation of the tool guide 4 about the axis of the trajectory 41 corresponds to the same insertion position since the guide tube remains unchanged). Specifically, this can provide the doctor with a free and available working space.

[0098] The haptic feedback allows the doctor to sense the exact moment of reaching the insertion position. The haptic feedback may also optionally allow the doctor to sense the approach of the insertion position. This makes it easy and intuitive to return to the insertion position.

[0099] For example, in a specific embodiment, the control unit 12 may be configured to reduce the movement speed of the tool guide 14 when the tool guide 14 approaches the insertion position. Such an arrangement enables the doctor to sense the approach of the insertion position.

[0100] Specifically, the moving speed of the tool guide 14 can be controlled according to the change in the distance between the current position of the tool guide and the insertion position. For example, the moving speed of the tool guide 14 is controlled according to the change in the gain factor of the force applied by the doctor on the tool guide, and the control unit is configured to gradually decrease the value of the gain factor according to the change in the distance between the current position and the insertion position. Such a gradual decrease in the gain factor may start only when the distance between the current position and the insertion position is less than a first threshold.

[0101] Optionally and / or additionally, when the distance between the current position of the tool guide and the insertion position is less than a second threshold, regardless of the force applied by the doctor on the tool guide 14, the control unit 12 can be configured to limit or maintain the moving speed of the tool guide 14 at a predetermined speed.

[0102] When the tool guide 14 reaches the insertion position, such an arrangement gives the user a feeling of a virtual incision.

[0103] The reduction of the moving speed of the tool guide to a particularly low speed corresponds to such a haptic feedback that enables the doctor to sense the proximity of the insertion position.

[0104] Optionally and / or additionally, the control unit 12 can also be configured to prohibit any movement of the tool guide 14 for a predetermined period of time when the insertion position is reached. The sudden stop of the movement of the tool guide corresponds to the haptic feedback, allowing the doctor to sense the exact moment of reaching the insertion position.

[0105] Figure 14 Specific implementation examples are shown. For a constant force applied by the doctor on the tool guide 14, the moving speed v of the tool guide changes according to the change in the distance d between the current position and the insertion position. In regions 61 and 62, the moving speed of the tool guide 14 is determined by applying a gain factor to the force applied by the doctor. When the distance between the current position and the insertion position is greater than a first threshold d1, the gain factor is constant (region 61 in the figure). When the distance is between the first threshold d1 and a second threshold d2 less than d1, the gain factor gradually decreases with the distance (region 62 in the figure). When the distance is less than the second threshold d2, the moving speed of the tool guide 14 is forced to a predetermined value (region 63 in the figure). When the distance becomes zero, the moving speed of the tool guide 14 becomes zero within a predetermined period of time.

[0106] The haptic feedback can consider other options (as an alternative and / or supplement to the above options), such as the vibration of the tool guide 14 when the insertion position is reached.

[0107] The control unit 12 may also be configured to provide a visual indication of the distance between the current position and the insertion position of the tool guide 14, or a visual indication that the tool guide has reached the insertion position. For example, the distance between the current position and the insertion position of the tool guide 14 can be displayed in numerical or gauge form on a user interface (e.g., on a monitor-type display screen, or on the screen of an augmented reality mask). When the insertion position is reached, i.e., when the distance between the current position and the insertion position of the tool guide 14 becomes zero, a marker (e.g., a green circle) can also be displayed.

[0108] The control unit 12 may also be configured to provide an audible indication of the distance between the current position and the insertion position of the tool guide 14, or an audible indication that the tool guide has reached the insertion position. For example, the frequency at which the audible signal repeats can increase as the distance between the current position and the insertion position of the tool guide 14 decreases. For example, when the insertion position is reached, the audible signal can become a continuous sound. Alternatively, a specific sound can be emitted when the insertion position is reached.

[0109] Thus, the control unit 12 can be configured to use one or more of tactile, visual, and audible indications to provide information about the distance between the current position and the insertion position of the tool guide 14, or to provide information that the tool guide 14 has reached the insertion position, and even to provide information when the tool guide has exceeded the insertion position.

[0110] Figures 11 - 13 An exemplary embodiment of the holding system 50 for the tool guide 14 is shown. Referring to Figures 7 - 8 of the present application, this embodiment of the holding system is similar to the embodiment described in patent application WO 2020 / 20286A1. In this exemplary embodiment, the holding system 50 for the tool guide 14 includes two jaws 51, 55. The jaws 51, 55 can be in a closed position (as Figure 12 shown) and an open position (as Figure 13is driven between the positions (as shown). Each jaw has grooves 52, 56. The grooves 52, 56 extend transversely with respect to the teeth 53, 57, which are arranged to engage with each other when the holding system 50 is in the closed position (each tooth 53, 57 has a part of the grooves 52, 56). In the closed position, the grooves 52, 56 are continuous and define a guide tube 59 for holding the medical device 15 and guiding its translation. In the open position, the grooves 52, 56 are spaced apart from each other for placing or releasing the medical device 15. Thus, the closed position corresponds to the position of guiding the medical device, and the open position corresponds to the position of releasing the medical device. In the insertion position, the guide tube 59 takes a position coaxial with the planned trajectory 41. The pressure applied by the doctor on the lever 58 formed by the support surface of one of the jaws ( Figures 11 - 13 the jaw 55 in the illustrated example) can cause a change from the closed position to the open position.

[0111] As Figures 12 - 13 shown, in the coaxial control mode, the control unit 12 is configured to transfer the force applied by the doctor on the tool guide 14 to a virtual application point A', and the virtual application point A' is positioned such that the pressure applied on the lever 58 axis, forms a particularly small angle θ, for example less than 20 degrees, even less than 10 degrees, with the axis (AA') passing through the actual application point A and the virtual application point A' of the pressure .

[0112] When the tool guide is very close to the patient's skin, the doctor presses the lever 58 to open the jaws 51, 55 in order to place the medical device 15 in place. Then, the doctor releases the lever 58, enabling the tool guide to hold the medical device 15 (while allowing it to slide along the guide tube 59). Then, the doctor can continue to partially insert the medical device 15. Before returning the tool guide 14 to the insertion position to complete the insertion of the medical device 15, the doctor can press the lever 58 again to open the jaws 51, 55 of the tool guide. Alternatively, without pressing the lever 58, the jaws of the tool guide close during the sliding of the guide along the needle.

[0113] The specific position of the virtual application point A' of the force considered in the control law enables the doctor to avoid untimely rotation of the tool guide 4 when pressing the lever 58 to open the jaws 51, 55 of the tool guide, and then reposition the tool guide 14 to the insertion position.

[0114] In fact, due to the small angle θ, the pressure applied on the lever 58 The torque is very small, which allows the doctor to avoid (or at least greatly limit) untimely rotation of the tool guide 14 when pressing the lever to open the jaws 51, 55 of the tool guide.

[0115] This configuration allows for an intuitive transition from a translation control mode to a rotation control mode: pressure on the lever 58 does not cause rotation of the tool guide 14; conversely, pressure applied on another part of the tool guide 14 causes rotation of the tool guide 14.

[0116] This intuitive transition from translation control to rotation control is implemented by combining the design of the tool guide 14 and the definition of the virtual application point A' of the force in the control law. Specifically, the doctor does not need to use a user interface (control pedal 19, dedicated physical buttons, virtual buttons on the control screen, etc.) to switch from translation control to rotation control.

[0117] The pressure applied on the lever 58 has a torque that depends not only on the cosine of the angle θ but also on the distance AA' between the virtual application point A' and the actual application point A of the pressure. Therefore, it is also advantageous to position the virtual application point A' at a shorter distance from the support surface of the lever 58 (e.g., less than 5 cm).

[0118] It should be noted that examples of other embodiments of the holding system 50 of the tool guide 14 can be compatible with the idea of advantageously positioning the virtual application point A' with respect to the pressure applied by the doctor on the lever 58 of the holding system 50 (e.g., referring to the Figures 2 - 6 embodiment of the holding system described in patent application WO 2020 / 201286A1 of this application).

[0119]

[0120] The above description clearly shows that, through its various features and advantages, the present invention achieves the set goal. The proposed solution actually allows the medical device 15 to be inserted without deviating from the planned trajectory 41. With the collaborative axial control mode, the doctor can easily achieve bringing the tool guide 14 as close as possible to the patient's skin to perform partial insertion of the medical device 15, and then reposition the tool guide 14 to the planned insertion position. The haptic feedback allows returning to the insertion position to be easy and intuitive. The specific design of the tool guide 14 combined with the specific position of the virtual application point A' considered in the control law also enables the tool guide to be intuitively switched from translation control to rotation control.

[0120] It should be noted that the present invention has been described using an optical navigation system. However, in a variant, there is no limitation to using an electromagnetic navigation system instead of the optical navigation system. In this case, the various "markers" (markers appearing on the patient reference 22, markers appearing on the tool guide 14) detectable by the navigation system will correspond to electromagnetic sensors, the positions of which can be determined by the navigation system in the generated electromagnetic field.

Claims

1. A medical robot (10) for assisting a physician during minimally invasive medical intervention on a target anatomical structure (45) of a patient (20), The medical robot (10) comprises a robotic arm (13), wherein a tool guide (14) is provided at a distal end of the robotic arm (13), wherein the tool guide (14) is used to guide at least a portion of a medical instrument (15) to be inserted into a body of a patient (20) along a planned straight line trajectory (41) between an entry point (43) located at the level of the patient's skin and a target point (44) located within a target anatomical structure (45), The medical robot (10) comprises a control unit (12) configured to control the robot arm (13) to move a tool guide (14). The control unit (12) is configured to determine and store an insertion position based on the planned trajectory (41), the insertion position corresponding to the placement and orientation that the tool guide (14) is to maintain as the physician continues to insert the medical instrument into the target point, In the "automatic control" mode, the control unit (12) is configured to automatically move the tool guide (14) to the insertion position, In the "cooperative axial control" mode, the control unit (12) is configured to determine the force applied by the physician on the tool guide (14) by means of a force sensor (16) coupled to the tool guide (14), and to determine the movement speed of the tool guide (14) as a function of the force thus determined, the movement of the tool guide (14) being constrained so as to adopt only: - allowing translational movement of the tool guide (14) along the axis of the planned trajectory (41), or - allowing translational movement of the tool guide (14) along the axis of the planned trajectory (41), and rotational movement of the tool guide (14) around the axis of the planned trajectory (41), In the coordinated axial control mode, the control unit (12) is configured to provide tactile feedback to the physician when the tool guide (14) returns to the insertion position.

2. The medical robot (10) according to claim 1, wherein in the collaborative axial control mode, when the distance between the current position of the tool guide and the insertion position is less than a first threshold value, the control unit (12) is configured to calculate the moving speed of the tool guide (14), and the moving speed changes with a gain factor applied to the force applied by the doctor on the tool guide (14), and the value of the gain factor gradually decreases with the change of the distance between the current position and the insertion position.

3. The medical robot (10) according to any one of claims 1 and 2, wherein in the collaborative axial control mode, when the distance between the current position of the tool guide and the insertion position is less than a second threshold, regardless of the force applied by the doctor on the tool guide (14), the control unit (12) is configured to limit or maintain the movement speed of the tool guide (14) at a predetermined speed.

4. The medical robot (10) according to any one of claims 1 to 3, wherein in the collaborative axial control mode, the control unit (12) is configured to prohibit any movement of the tool guide (14) within a predetermined time period when the insertion position is reached.

5. The medical robot (10) according to any one of claims 1 to 4, wherein the tool guide (14) comprises at least one marker (147) detectable by a navigation system (30), and the control unit (12) is configured to: - receiving from the navigation system (30) a first item of information relating to the position of the tool guide (14) in the reference system of the navigation system (30), - receiving from the navigation system (30) a second information item relating to the insertion position that the tool guide (14) must adopt in the reference system of the navigation system (30) in order to guide the medical instrument (15) along the planned trajectory (41) until the target point is reached, - determining the insertion position in the reference system of the medical robot (10) based on the first information item and the second information item.

6. The medical robot (10) according to claim 5, wherein the second information item corresponds to a position of a patient reference (22) in a reference system of the navigation system (30), the patient reference (22) being used to be placed on the patient (20) to approach a target anatomical structure, the patient reference (22) comprising at least one marker (221) detectable by the navigation system (30) and at least one radiopaque marker (222), and the control unit (12) being configured to determine the insertion position based on the position of the patient reference (22) and the planned trajectory (41), the trajectory (41) being defined with the aid of a pre-interventional medical image (40) and relative to the position of the patient reference (22), the target anatomical structure of the patient and the at least one radiopaque marker (222) of the patient reference (22) being visible on the pre-interventional medical image (40).

7. The medical robot (10) according to any one of claims 1 to 6, wherein the part of the medical instrument (15) for penetrating the patient's body has axial symmetry along an axis, during the insertion of the medical instrument (15), the axis corresponds to the axis of the planned trajectory, and in the collaborative axial control mode, the movement of the tool guide (14) is constrained to limit the tool guide to translational movement along the axis of the planned trajectory (41) and rotational movement of the tool guide (14) around the axis of the planned trajectory (42).

8. The medical robot (10) according to claim 7, wherein: The tool guide (14) comprises two jaws (51, 55), each jaw comprising a groove (52, 56), the jaws being able to be driven between a closed position and an open position, in which the grooves (52, 56) are continuous and define a guide tube (59) for holding the medical device (15) and guiding the medical device (15) in translation, and in which the grooves (52, 56) are spaced apart from each other to place or release the medical device (15), the guide tube adopting a position coaxial with the planned trajectory in the insertion position, the doctor being able to achieve the change from the closed position to the open position by pressing a lever (58) formed by a support surface of one of the jaws (55), In the coordinated axial control mode, the control unit (12) is configured to transfer the force applied by the surgeon on the tool guide (14) at a virtual application point (A'), the virtual application point (A') being positioned such that the pressure applied on the lever (58) The axis passes through the pressure The axis (AA') of the actual application point (A) and the virtual application point (A') forms an angle (θ) less than 20 degrees.

9. The medical robot (10) according to any one of claims 1 to 8, wherein the robotic arm (13) comprises at least six degrees of freedom.

10. The medical robot (10) according to any one of claims 1 to 9, wherein the control unit (12) is configured to provide a visual indication and / or an auditory indication when the tool guide (14) returns to the insertion position or when the tool guide (14) exceeds the insertion position.

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