Surgical system

Abstract

This disclosure relates to a surgical system for processing anatomical structures according to a plurality of target planes and / or axes, the surgical system comprising: - a robotic device (1) including: - an end effector (2) defining a current plane or axis; - an actuation unit (11) coupled to the end effector (2); - a tracking unit (3) configured to determine the pose of the current plane or axis; - a control unit coupled to the tracking unit and configured to control the actuation unit (11) to align the current plane or axis of the end effector (2) with each of a plurality of target planes and / or axes for processing the anatomical structure, the robotic device It can operate in at least the following modes: - working mode, in which processing is performed using the end effector while being constrained to a target plane or axis by the actuation unit, and - waiting mode, in which no processing is performed and the actuation unit is operable to move the end effector to align with another target plane or axis, wherein the control unit is also configured to: (a) determine that the robot device (1) is in waiting mode; (b) detect a triggering force applied to the end effector (2) and / or the actuation unit (11) in at least one first direction; and (c) as a result of determining (a) and detecting (b), trigger a position change of the end effector (2) by the actuation unit (11) to align the current plane or axis with the next target plane or axis.

Description

Technical Field

[0001] This disclosure relates to a surgical system including a robotic device and a method for triggering positional changes of such a robotic device. Background Technology

[0002] Some surgical procedures require multiple steps, including the manipulation of anatomical structures.

[0003] For example, total knee arthroplasty typically requires cutting both the femoral and tibial epiphyses to remove damaged bone and cartilage and install a knee prosthesis. To do this, the surgeon must use a tactile saw to make five or more cuts in the femur and one or more cuts in the tibia using a cutting block.

[0004] Figure 1 This is a schematic perspective view of a knee intended to receive a knee prosthesis comprising a femoral component (FC) and a tibial component (TC). Generally, the cuts made on the femoral F are: a distal cut along plane F1, an anterior cut along plane F2, a posterior cut along plane F3, and an anterior oblique cut (F4) and a posterior oblique cut (F5) connecting the distal plane to the anterior and posterior planes, respectively. Cuts must be made on the tibial T along plane T1.

[0005] Robotic systems have been developed to enable surgeons to accurately execute all these planes in a shorter amount of time.

[0006] For example, document WO 2018 / 103945 proposes a robotic system comprising a motorized actuation unit, a planar mechanism having a first end attached to an end segment of the actuation unit, and a second end rigidly attached to an end actuator serving as a saw. The saw includes a body, a saw blade movable relative to the body, and a handle configured to be held by a surgeon to perform cuts. The robotic system also includes trackers (not shown) attached to the saw and the patient, respectively, for determining the relative position of the saw and the bone to be cut in real time, and a control unit configured to compensate for minute movements from the patient or surgeon, for maintaining alignment of the saw blade with a defined plane that it must cut. Figures 2A-2F Perspective views of such a robotic device 1 are shown when performing tibial cuts, distal cuts, anterior cuts, posterior cuts, anterior oblique cuts, and posterior oblique cuts, respectively.

[0007] The control of the end effector position used to perform each cutting step can typically be defined as a sequence of three steps performed in a loop:

[0008] - Phase 1: The robotic device maintains the cutting position before and during the cutting process; the robotic device should not deviate from the desired cutting position as long as the bone cutting is not completed;

[0009] - Phase 2: Cutting complete; the robot awaits instructions to move to the next cutting position; meanwhile, the robot typically maintains the end effector position at the previous cutting position.

[0010] - Phase 3: After receiving instructions from the user, usually for safety reasons, the robot will move the end effector to the next cutting position.

[0011] To trigger the transition from Phase 2 to Phase 3, users may have to use a foot switch, a button located on the end effector or robot device, or a virtual button integrated into the software graphical user interface and displayed on a touchscreen.

[0012] This triggering process may require the user to locate the foot switch in an unseen area, remove his / her hand from the end effector, and / or instruct another person to activate the robot device, which is time-consuming, disrupts the user's workflow, and may cause inconvenience. Summary of the Invention

[0013] Therefore, it is desirable to determine a system and method for triggering positional changes of robotic devices that is more ergonomic for users.

[0014] The implementation scheme relates to a surgical system for processing anatomical structures according to multiple target planes and / or axes, the surgical system comprising:

[0015] - A robotic device, comprising:

[0016] - An end effector that defines the current plane or axis.

[0017] - An actuation unit, which is connected to the end effector.

[0018] - A tracking unit configured to determine the pose of the current plane or axis.

[0019] - A control unit, which is coupled to the tracking unit and configured to control the actuation unit to align the current plane or axis of the end effector with each of a plurality of target planes and / or axes used to process the anatomical structure.

[0020] The robotic device can operate in at least the following modes:

[0021] - Operating mode, in which processing is performed using an end effector while being constrained to a target plane or axis by an actuation unit, and

[0022] - Waiting mode, where no processing is performed and the actuation unit is operable to move the end effector to align with another target plane or axis.

[0023] The control unit is also configured to:

[0024] (a) Determine that the robot device is in waiting mode;

[0025] (b) Detecting the triggering force applied to the end effector and / or actuation unit in at least one first direction;

[0026] (c) As a result of determining (a) and detecting (b), the position change of the end effector is triggered by the actuation unit to align the current plane or axis with the next target plane or axis.

[0027] Thanks to the system, the triggering process is made easier and faster because the user can apply the triggering force directly to the robotic device in front of him / her.

[0028] In some implementations, the end effector includes at least one of the following: a cutting tool such as a saw, burr, or drill; a cutting guide; and a guiding tool.

[0029] In some implementations, the tracking unit includes a tracker rigidly attached to the end effector and / or actuation unit.

[0030] The implementation scheme relates to a method for triggering positional changes in a robotic device for processing anatomical structures based on multiple target planes and / or axes. The robotic device includes an end effector defining a current plane or axis and an actuation unit coupled to the end effector. The robotic system can operate in at least the following modes:

[0031] - Operating mode, in which processing is performed using an end effector while being constrained to a target plane or axis by an actuation unit, and

[0032] - Waiting mode, where no processing is performed and the actuation unit is operable to move the end effector to align with another target plane or axis.

[0033] The method includes:

[0034] (a) Determine that the robot device is in waiting mode;

[0035] (b) Detecting the triggering force applied to the end effector and / or actuation unit in at least one first direction;

[0036] (c) As a result of the determination and detection performed in steps (a) and (b), the position change of the end effector is triggered by the actuation unit to align the end effector with the next target plane or axis.

[0037] Triggering force may include at least one of linear force and torque.

[0038] In some implementations, step (b) includes sensing a current value greater than a first threshold in at least one servo motor of the actuation unit.

[0039] In some implementations, step (b) includes sensing a displacement of the end effector greater than a second threshold. This displacement of the end effector can be sensed based on tracking data from the tracking unit.

[0040] In some implementations, step (b) includes detecting a sequence of external linear forces and / or torques applied to the end effector and / or actuation unit.

[0041] In some implementations, the end effector includes a power tool with a trigger, and step (b) further includes detecting pressure applied to the trigger when the tool is in the off state.

[0042] In some implementations, the position change of the end effector is performed substantially according to the first direction.

[0043] In some implementations, the method may include stopping the triggered movement of the robot device due to the detection of an external force different from the triggering force.

[0044] In some implementations, step (a) includes using medical images and / or anatomical landmarks to determine the position of the end effector relative to anatomical structures.

[0045] In some implementations, step (b) further includes sensing the duration of the applied external force and comparing the sensed duration with a duration threshold.

[0046] In some implementations, in step (c), the control unit triggers the displacement of the end effector (2) by a determined offset magnitude in a first direction, and the offset is canceled when the triggering force is released. Attached Figure Description

[0047] Referring to the accompanying drawings, further embodiments and advantages will be described in the following detailed description, wherein:

[0048] Figure 1 The diagram illustrates the cuts that will be made in the femur and tibia for the implantation of a knee prosthesis;

[0049] Figures 2A-2F Perspective views of the robotic apparatus for performing tibial cuts, distal cuts, anterior cuts, posterior cuts, anterior oblique cuts, and posterior oblique cuts are shown respectively.

[0050] Figure 3 A perspective view of a surgical system according to one implementation scheme;

[0051] Figure 4A perspective view of a robotic device according to one embodiment;

[0052] Figure 5 A flowchart illustrating a method for triggering position changes in a robotic device is shown. Detailed Implementation

[0053] The robotic device includes a base, an end effector defining a current plane or axis, and a motor actuation unit coupled to the end effector to move the end effector relative to the base.

[0054] In some implementations, the end effector may be a bone-cutting tool, such as a saw, burr, or drill. If the tool is a surgical saw, the end effector defines a current plane, which is the plane in which the saw blade oscillates. If the tool is a burr or drill, the end effector defines a current axis, which is the longitudinal axis of the burr or drill.

[0055] In other embodiments, the end effector may include a cutting guide, which is a rigid block including at least one through hole in the form of a slot (defining the current plane) or a cylindrical hole (defining the current axis), configured to guide a bone cutting tool that can be freely moved by a user according to the current plane or axis.

[0056] In other embodiments, the end effector may include a guiding tool for guiding an implant insertion tool, such as an implant impactor or screwdriver, according to the current axis.

[0057] In some implementations, the end effector can be connected to the actuation unit via a planar mechanism configured to restrict the movement of the cutting tool within the cutting plane.

[0058] Advantageously, the cutting tool can be separated from the planar mechanism. Preferably, especially when the cutting tool is not intended to receive a tracker, the attachment device for the cutting tool provides reproducible fixation.

[0059] Several different architectures exist for implementing planar mechanisms. For example, a planar mechanism may consist of only a rotational axis and then a translational axis that carries the cutting tool along its longitudinal direction. Alternatively, a planar mechanism may consist of two orthogonal translational axes and then a rotational axis. According to another embodiment, the planar mechanism may be an arched slider that includes a rotational axis and then a translational axis that carries the cutting tool.

[0060] According to one implementation, the planar mechanism is passive, meaning it is not motorized and can be freely manipulated by the user. One advantage of this passive mechanism is that it preserves all the user's perception when manipulating the saw within bone. For example, surgeons use it to freely manipulate the saw within a cutting block and detect when the saw blade has reached the back of the bone by sensing changes in bone resistance, and this perception is fully preserved using a passive planar mechanism with very low friction at its joint.

[0061] Alternatively, the planar mechanism may be at least partially effective, i.e., including at least one degree of motion. If the planar mechanism is movable, i.e., it has at least two degrees of motion, cutting can be performed automatically. It should be noted that all degrees of motion are configured to move the cutting tool within the cutting plane.

[0062] Regardless of the implementation, the planar mechanism may include a locking system that locks each of its degrees of freedom once the cutting plane is aligned with the target plane.

[0063] The actuation unit may have a serial architecture consisting of multiple moving segments. In some embodiments, the actuation unit has three rotational degrees of freedom for adjusting the position and orientation of the cutting plane relative to each target plane. In other embodiments, the actuation unit has two rotational degrees of freedom and one or two translational degrees of freedom. Generally, the actuation unit includes three to five degrees of freedom, of which at least two are rotational degrees of freedom orthogonal to each other. The segments and their components are integrated in an optimal manner so that the robotic device remains as compact and lightweight as possible, while maintaining sufficient strength to hold the planar mechanism and surgical instruments, as well as to resist some normal pressure exerted by the user when he / she manipulates the surgical instruments.

[0064] In some implementations, the architecture of the actuation unit consists of three rotational degrees of freedom.

[0065] In some implementations, the segments are arranged such that the first axis of rotation and the third axis of rotation are substantially parallel to each other, and the second axis is substantially orthogonal to the first axis and the third axis.

[0066] In other embodiments, the first axis and the second axis, or the second axis and the third axis, are substantially parallel to each other, and the first axis is substantially orthogonal to the third axis.

[0067] When used in knee arthroplasty (TKA, UKA, etc.), the robotic device can be placed on the medial (internal) or lateral (external) side of the leg of interest. The first axis of rotation is intended to be substantially orthogonal to the sagittal plane of the knee. For any application of the robotic system, it is possible to define some easily identifiable anatomical landmarks and use them to align the actuating units in the spherical region.

[0068] In some implementations, the architecture of the actuation unit can enable additional movement within the cutting plane—which can be motorized or non-motorized.

[0069] As will be explained in more detail below, the actuation unit is controlled by a control unit. The control unit can be integrated into the robotic device or located remotely.

[0070] The system may include an articulated, lockable retaining arm that supports the base of the robotic device and is adapted to connect to a mechanical support, such as an operating table, a leg retainer, or to be mounted on a wheel-blocking trolley. The leg retainer is an adjustable mechanism configured to hold the legs in a given flexed position when the patient is lying on the operating table.

[0071] The retaining arm can be made of several articulated sections using ball joints, swivel joints, and / or translation joints.

[0072] The retaining arm can be manually locked by a knob (mechanical locking system) or actively locked by a dedicated actuator of the locking system. The locking system can be an electrical system, piezoelectric system, hydraulic system, pneumatic system, or a combination of these systems (e.g., a hydraulic cylinder driven by an electric motor). For example, Smith & Nephew sells an actively lockable passive retaining arm named Spider. TM Actuators can be buttons, foot switches, remote buttons, etc. In order to operate the robot device, the user must keep the actuators activated until the desired pose of the robot device has been achieved.

[0073] The arm supports the weight of the robotic device and keeps it in approximate position relative to the anatomical structure to be treated. When operating the device, it restricts the user's movement—and in an advantageous embodiment, also blocks movement of the user and / or patient, vibrations of the cutting tool, and reactive forces caused by movement of the actuator.

[0074] According to one implementation scheme, the arm is kept passive.

[0075] Advantageously, the retaining arm can be gradually braked based on the distance between the robotic device and its target position relative to a tracker fixed to the patient. For example, the braking force can be inversely proportional to the distance of the robotic device from its target position. Alternatively, one or more concentric volumes (e.g., cubes or spheres) can be defined around the target position of the robotic device. The braking force can be adjusted based on the presence of the robotic device in one of these volumes. Thus, as the robotic device approaches the target position, the retaining arm is braked and the user can receive force feedback information. Alternatively, the feedback information can be provided in the form of light or sound signals. For example, a variable flash frequency and / or the intensity of the light signal can indicate the distance between the robotic device and its target position. Similarly, a variable frequency, repetition rate, and / or amplitude of an acoustic signal can indicate this distance. In any case, incomplete braking allows the user to always be able to manipulate the robotic device until it reaches the final desired position. The retaining arm is then locked upon user action (e.g., by operating an actuator, such as releasing or pressing a button). If the user wants to move the robotic device again, he / she must operate the actuator again, which releases the retaining arm – possibly with the braking force described above. If a new target position for the robotic device is defined, a new braking amount is defined, and the braking is adjusted based on the new volume.

[0076] Preferably, the connection between the retaining arm and the actuation unit is placed as close as possible to the first segment of the actuation unit or the center of gravity of the robot device to minimize any lever arm effect. The portion of the actuation unit attached to the retaining arm is referred to as the base of the robot device.

[0077] According to one embodiment, the base of the robotic device can be fixed relative to the retaining arm. This architecture is advantageous because it minimizes the weight of the moving parts of the actuation unit. As a result, the robotic device can be more responsive, which is beneficial for real-time control of the cutting plane or axis.

[0078] The system also includes a tracking unit configured to determine the pose of the saw relative to the anatomical structure to be cut in real time.

[0079] The tracking unit may include a tracking system that is known in itself.

[0080] Tracking systems commonly used in computer-assisted surgery employ various technologies (passive optics, active optics, electromagnetic, inertial with gyroscope measurement, ultrasound, etc.), which can be used individually or in combination. According to a preferred embodiment, the tracking system is based on passive optics technology.

[0081] The tracking unit includes at least one tracker that can be attached to any component of the actuation unit, such as to a moving segment within a moving segment.

[0082] Because of the encoders or sensors of the servo motors and the calibration model of the robot device (including all axes and distances of the actuation unit segments), the position of each segment of the actuation unit is known in real time. Using this model and well-known geometric modeling techniques in robots, it is possible to calculate the relative positions of all segments. Therefore, if a measurement is known in a coordinate system attached to the base of the robot device using an external tracker, the position of any segment is also known in the same coordinate system. Furthermore, if a tracker is attached to the base of the actuation unit and a second tracker is attached to the anatomical structure, the pose of any segment of the actuation unit is known in the coordinate system of the tracker attached to the anatomical structure.

[0083] The control unit is coupled to the tracking unit and configured to control the actuation unit to align the current plane or axis of the end effector with each of the multiple target planes and / or axes used to process the anatomical structure.

[0084] Figure 3 This illustrates a general overview of the surgical system. In an exemplary embodiment of the robotic device, the end effector 2 includes a burr. However, other components of the system can be used with other end effectors as described above.

[0085] The robotic device 1 includes a base 10, a motorized actuation unit 11, and an end effector 2 serving as a surgical burr. The burr is connected to the actuation unit via a planar mechanism 12, wherein a first end is attached to the end section of the actuation unit, and a second end is rigidly attached to the burr 2.

[0086] Especially if the burr head is very small (e.g., with a diameter on the order of three mm), the operation of the burr, confined to the cutting plane, allows for planar cutting. The burr tip can be spherical or cylindrical. Typically, a cylindrical burr tip with a diameter of three mm is confined by a planar mechanism to remain in a plane parallel to the cylindrical axis. This cylindrical burr tip has sufficient rigidity for large cuts and is small enough to perform rapid cuts.

[0087] Base 10 can be attached to a lockable retaining arm (not in) Figure 3 (as shown in the image).

[0088] Tracker 30 is attached to the bone B to be cut.

[0089] Tracker 31 is attached to end effector 2, and another tracker 32 is attached to the base 10 of the robotic device for determining the relative position of the end effector and the bone to be cut in real time.

[0090] In the illustrated embodiment, trackers 30, 31, and 32 are optical trackers and are tracked via positioning camera 3. In other embodiments, the tracker may be an electromagnetic tracker that is tracked via an electromagnetic tracking unit.

[0091] The control unit (not shown) controls the actuation unit to keep the current axis of the burr along the target axis to compensate for minute real-time movements from the patient or surgeon.

[0092] The tracker 32 attached to the base 10 is sufficient to control the robot device because the model of the robot device and the position of the servo motor of the actuator are known, but the tracker 31 attached to the end effector provides additional information about the position and orientation of the burr.

[0093] Figure 4 Another embodiment of the robotic device is shown, wherein the end effector includes a saw. Figure 3 Components with the same label have the same function and therefore do not need to be described again.

[0094] The robotic device 1 includes a base 10, a motorized actuation unit 11, and an end effector 2 that serves as a surgical saw. The saw is connected to the actuation unit 11 via a planar mechanism 12.

[0095] The base 10 is rigidly attached to the end of the lockable retaining arm 13. Figure 4 The opposite ends of the invisible arm 13 can be rigidly attached to the operating table or rigidly attached to a trolley placed near the operating table.

[0096] Although not shown, the tracker (e.g., an optical or electromagnetic tracker) is attached to the patient's anatomy and the robotic device (e.g., attached to the base and advantageously also to the end effector).

[0097] Figure 5 A flowchart illustrating an implementation scheme of the method carried out by the control unit.

[0098] Before implementing the method, the user can plan multiple target planes or axes. This planning step can be accomplished using techniques known per se and will not be described herein. Typically, the user determines not only the position and orientation of each target plane or axis relative to the anatomical structure, but also the order in which they will be cut. Therefore, planning may include a sequence of at least two cuts based on the different target planes or axes to be cut in the determined order. The plan may be generated by the control unit itself, or it may be generated by another device and transferred to the control unit.

[0099] For safety reasons, the end effector cannot be moved to another position when cutting is being performed.

[0100] Therefore, in the first step (step 100), the control unit must determine that the robot device is waiting for an instruction to align the end effector with the target plane or axis (waiting mode).

[0101] This determination can be made through different techniques that can be combined.

[0102] For example, if the end effector is a power tool (e.g., a surgical saw, drill, or deburr), then the tool being in the off state can be an indication that a previous cutting step has been completed and the end effector must be aligned with the next target plane or axis. In practice, the end effector cannot be moved during the processing (operating mode).

[0103] However, this closed state alone may not be sufficient and can be supplemented by other information, such as calculations of the cutting completion degree by an algorithm implemented by the control unit. These calculations may be based, for example, on the geometry of the bone and the path or position of the end effector.

[0104] Another possibility is to use medical images and / or anatomical landmarks to determine the position of the end effector relative to the anatomical structure. In practice, when a cut is complete, the user or robotic device can retract the end effector from the bone to await the next cut. Therefore, a given distance between the end effector and the anatomical structure can indicate the robotic device's waiting status.

[0105] Based on the anatomical structure and the positioning data of the end effector provided by the tracker, the control unit can calculate the distance between the surface of the anatomical structure and the end effector.

[0106] If medical images of the anatomical structure are available, the distance between the surface of the anatomical structure and the end effector from the processed image can also be determined. The medical image may be a preoperative 3D image (e.g., a CT scan or MRI image) used for navigating the end effector. Alternatively, the medical image may be a 2D or 3D intraoperative image.

[0107] In image-free systems, intraoperative acquisition of anatomical landmarks via pointer trackers by the tracking unit can also allow for determination of the distance between the surface of the anatomical structure and the end effector.

[0108] In the second step (step 200), the control unit must detect the external force applied to the end effector or actuation unit in at least one first direction. If applicable, the force may also be applied to a planar mechanism. More generally, the force may be applied to any part of the robotic device that is not rigidly connected to the retaining arm.

[0109] Such external forces can be applied by the user to the end effector to indicate the desired position change.

[0110] The external force (also referred to herein as the “triggering force”) may be in the form of a linear force and / or torque.

[0111] For safety reasons, it may be preferable that the triggering force combines at least one linear force and at least one torque, or combines at least two linear forces, in different directions or in the same direction within a given time period, or combines at least two torques in different directions or in the same direction within a given time period. In other words, the triggering force can combine at least two forces or torques according to a predetermined sequence. The sequence can preferably be defined by predetermined spatial parameters (e.g., one or more directions) and temporal parameters (e.g., the duration of the applied force or torque and / or the time period between the application of consecutive forces or torques), which together constitute a predetermined signal that will be understood by the control unit as a sequence for moving the end effector to a new position. In this way, the risk of triggering undesirable position changes can be minimized.

[0112] Preferably, the sequence can be designed to make it less likely to occur involuntarily. For example, the sequence may include at least one positive torque and one negative torque continuously applied to the end effector in a first direction. Alternatively, the sequence may include at least one torque applied about a first axis and a force applied along a second axis perpendicular to the first axis. In another example, a force may be applied to the actuation unit, and the end effector may oscillate back and forth with a large amplitude due to a planar mechanism.

[0113] Trigger force detection can be accomplished through a combination of techniques. These techniques typically involve components already present in the system.

[0114] In some implementations, the trigger force can be detected by sensing a current value greater than a first threshold in at least one servo motor. In practice, applying an external force to the actuation unit or end effector causes a force or torque to be generated by at least one servo motor to act under the applied force and hold the end effector in its current waiting position. The force or torque applied by the servo motor results in an increase in current consumption in the servo motor. This current can be measured (in amperes) by sensors of the servo motor, sensors of the control unit, and / or sensors of the unit powering the servo motor.

[0115] Depending on the direction of the external force applied to the actuator or end effector, the current can be increased in one or more motors of the actuator. A specific threshold can be defined for each associated servo motor.

[0116] Advantageously, the direction of the expected triggering force can be monitored more precisely, for example by requiring a smaller threshold for servo motors that can apply counterforce or torque in these directions.

[0117] In some implementations, the trigger force can be detected by sensing a displacement of the end effector greater than a second threshold.

[0118] The displacement can be sensed based on tracking data from a tracker attached to the end effector.

[0119] Advantageously, the direction of the expected triggering force can be monitored more precisely, for example, by requiring smaller displacement thresholds in these directions.

[0120] In addition to the direction of the force applied by the user, detection may also include sensing the duration of the applied triggering force, and detecting the triggering force only if the duration exceeds a third threshold. This is intended to prevent the end effector from being triggered to move to a new position by shocks or accidental pressure applied to the end effector or actuator unit.

[0121] To this end, the control unit may include a timer that is triggered by detecting a first event that may represent a desired signal. For example, an external force may need to be long enough to trigger movement of the robotic device. In that case, the control unit may trigger the timer when the current of a given servo motor is above a first threshold, and if the current remains above the first threshold for a duration greater than a third threshold, the control unit detects that the applied force is a signal. In some embodiments, the triggering force may be a sequence of different individual forces applied in the same or different directions. In that case, the control unit may determine the duration of each individual force and check whether each duration is within a given range.

[0122] When the triggering force to be detected is a combination of individual forces or torques, the time interval between the application of consecutive individual forces or torques can also be measured and compared with a predetermined range. Therefore, the control unit can detect the triggering force only if the time interval between the application of consecutive individual forces or torques is within the predetermined range.

[0123] As described above, the aforementioned detection techniques can be combined. For example, a user can first wiggle the end effector according to a defined pattern (e.g., left / right or right / left) due to the planar mechanism. This movement triggers an alarm in the control unit; the control unit can then trigger a timer to measure the time interval between this first event and the next event in the form of an applied triggering force. Thus, the user can apply the force to the end effector or actuation unit in a defined direction, which will be detected by the control unit.

[0124] In some implementations, the control unit and robotic device can be configured to provide a "button" feel to the user. In that case, applying a triggering force in a first direction causes the control unit to trigger displacement of the end effector by a defined magnitude in that first direction, resulting in an offset of the end effector relative to its initial position. For example, if the user applies a linear force, the end effector may typically translate 1 mm to 10 mm; if the user applies torque, the end effector may rotate 0.5° to 5°. This offset of the end effector can be canceled when the triggering force is released.

[0125] The "button" effect can be short, such that displacement of the end effector begins as soon as the user releases the trigger force, or displacement begins when the trigger force is applied, and the trigger force can then be released at any time after the movement has begun. The effect can also be long, such that displacement of the end effector begins and continues as soon as the user applies the trigger force. In the latter case, during the displacement, the instantaneous position of the end effector is offset compared to its position if this "button" action were not used. Once the trigger force is released, the offset is canceled.

[0126] The force applied to the end effector and / or actuation unit may not be the only parameter to be considered in the detection step. For example, if the end effector is a power tool, the detection of the trigger force can be combined with the detection of the user pressing on the tool's trigger. If the robot is in a standby state, pressing the trigger may not activate the tool, but it can generate an electrical signal that can be detected by the control unit. Therefore, the combined detection of the trigger force applied to the end effector and / or actuation unit in a given direction and the electrical signal in the power tool's trigger can be understood as the desired signal.

[0127] As a result of the first and second detection steps, the control unit triggers a position change of the end effector through the actuation unit to align the current plane or axis with the next target plane or axis (step 300).

[0128] In some implementations, the next target plane or axis can be the one spatially closest to the current plane or axis, meaning the plane or axis that needs to have the minimum displacement relative to the current position of the end effector. This minimum displacement can be considered in the direction of application of the trigger force.

[0129] In other implementations, the next target plane or axis may be the next or previous plane or axis according to the planned surgical workflow. If the cut must be redone or improved, for example, it may be necessary to return to the previous target plane or axis. Advantageously, the direction relative to the planned workflow (i.e., relative to the next or previous target plane or axis) can be indicated by the opposite direction of the triggering force. For example, an upward force may trigger a transition to the next step in the planned workflow, and a downward force may trigger a transition to the previous step in the planned workflow.

[0130] In some implementations, an external force other than the triggering force – or a sequence of forces and / or torques – can be used to stop the movement of the end effector, for example, by canceling a signal previously detected by the control unit.

[0131] Advantageously, the control unit is configured to record the status of a given cutting step. In other words, the control unit may be able to determine whether a cut according to a given plane or axis has been performed.

[0132] For example, after a previous cut has finished, the user might want to return to the distal cut to inspect the plane created by the saw blade. In this case, the robot will remain in waiting mode when it is back on the distal plane, since the cut has already been performed. If the user only wants to inspect the cut made by the saw blade, he can directly apply a trigger force to move the robot to the next cut without performing another cut.

[0133] Although the previous description focused on robotic devices with fewer than six degrees of freedom—distinguished from large surgical robots by lower inertia (particularly according to the first axis) and therefore greater responsiveness (especially for real-time compensation of bone movement)—this disclosure is also applicable to surgical robots with six degrees of freedom. In fact, these robots also integrate servo motors or other devices that allow the detection of triggering forces applied to the robot or end effector and control unit, which can be configured to trigger positional changes in the end effector in response to such triggering forces.

[0134] References

[0135] WO 2018 / 103945

Claims

1. A surgical system for processing anatomical structures according to multiple target planes and / or axes, the surgical system comprising: - Robotic device (1), the robotic device comprising: - End effector (2), which defines the current plane or axis, - Actuation unit (11), which is connected to the end effector (2). - Tracking unit (3), the tracking unit being configured to determine the pose of the current plane or axis, - A control unit, which is coupled to the tracking unit and configured to control the actuation unit (11) to align the current plane or axis of the end effector (2) with each of the plurality of target planes and / or axes for processing the anatomical structure. The robotic device is capable of operating in at least the following modes: - Operating mode, wherein processing is performed using the end effector while being constrained to a target plane or axis by the actuation unit, and - Waiting mode, where no processing is performed, and the actuation unit is operable to move the end effector to align with another target plane or axis. The control unit is further configured to: (a) Determine that the robot device (1) is in the waiting mode; (b) Detecting a triggering force applied to the end effector (2) and / or the actuation unit (11) in at least one predetermined first direction; (c) As a result of determining (a) and detecting (b), the position change of the end effector (2) is triggered by the actuation unit (11) to align the current plane or axis with the next target plane or axis.

2. The surgical system of claim 1, wherein the end effector (2) comprises a cutting tool.

3. The surgical system of claim 2, wherein the cutting tool is a saw, a burr, or a drill.

4. The surgical system of claim 1, wherein the end effector (2) includes a cutting guide.

5. The surgical system of claim 1, wherein the end effector (2) includes a guiding tool.

6. The surgical system according to any one of claims 1 to 5, wherein the tracking unit (3) comprises a tracker (31, 32) rigidly attached to the end effector (2) and / or the actuation unit (11).

7. The surgical system according to any one of claims 1 to 5, wherein the triggering force comprises at least one of linear force and torque.

8. The surgical system according to any one of claims 1 to 5, wherein in step (b), the control unit is configured to sense a current value greater than a first threshold in at least one servo motor of the actuation unit (11).

9. The surgical system according to any one of claims 1 to 5, wherein in step (b), the control unit is configured to sense a displacement of the end effector (2) greater than a second threshold.

10. The surgical system of claim 9, wherein the control unit is configured to sense the displacement of the end effector (2) based on tracking data from the tracking unit (3).

11. The surgical system according to any one of claims 1 to 5, wherein in step (b), the control unit is configured to detect a sequence of external linear forces and / or torques applied to the end effector and / or the actuation unit.

12. The surgical system according to any one of claims 1 to 5, wherein the end effector comprises a power tool having a trigger, and in step (b), the control unit is further configured to detect pressure applied to the trigger when the tool is in a closed state.

13. The surgical system according to any one of claims 1 to 5, wherein the actuation unit (11) is configured to change the position of the end effector substantially according to the first direction.

14. The surgical system according to any one of claims 1 to 5, wherein the control unit is further configured to stop the triggering movement of the robotic device upon detecting an external force different from the triggering force.

15. The surgical system according to any one of claims 1 to 5, wherein in step (a), the control unit is configured to use medical images and / or anatomical landmarks to determine the position of the end effector (2) relative to the anatomical structure (B).

16. The surgical system according to any one of claims 1 to 5, wherein in step (b), the control unit is further configured to sense the duration of applying the triggering force and compare the sensed duration with a duration threshold.

17. The surgical system according to any one of claims 1 to 5, wherein in step (c), the control unit is configured to trigger displacement of the end effector (2) by a determined offset magnitude in the first direction, and to cancel the offset upon release of the triggering force.

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