Method for controlling an articulated end effector actuated by one or more actuation tendons of a surgical instrument of a surgical robotic system with compensation for elastic-plastic elongation of the tendons, and related robotic system

Abstract

A method for controlling an articulated end effector actuated by an actuation tendon of a surgical instrument of a robotic surgical system during a motion phase of the surgical instrument is provided. The robotic surgical system includes an articulated end effector, an actuation tendon configured to actuate the articulated end effector, and an electric actuator that imparts motion to the actuation tendon. During the motion phase, the method estimates a desired target force related to a predicted elastic elongation of the actuation tendon when the electric actuator is in contact with the actuation tendon, detects an actual force the electric actuator imparts to the actuation tendon, estimates and / or calculates a length change due to plastic or elasto-plastic elongation of the actuation tendon based on a difference between the detected actual force and the desired target force, and uses the length change as a corrective input for controlling the electric actuator. A surgical robotic system configured to perform and / or be controlled by the method is provided.

Description

[Technical Field]

[0001] The present invention relates to a method for controlling an articulated end effector actuated by one or more actuation tendons of a surgical instrument of a surgical robotic system.

[0002] In particular, the present invention relates to a control method that includes compensation for plastic or elastoplastic elongation of actuated tendons.

[0003] Thus, the present specification relates more generally to the technical field of motion control of telesurgical robotic systems. [Background technology]

[0004] Known robotic systems for medical and / or surgical applications typically comprise at least one articulated terminal end (or "articulated end effector" or "end effector") intended to interact with a patient's anatomy to perform surgical or microsurgical procedures such as suturing, anastomosis, dissection, etc., or to obtain images or diagnostic information.

[0005] Articulated end effectors are typically actuated by actuation cables (tendons) that transmit traction motion to the articulated end effector.

[0006] Medical and surgical robotic systems can operate according to a master-slave control architecture, where the master can be operated by being handheld by a surgeon, or the master can operate in an autonomous mode, performing a series of programmed operations.

[0007] Anthropomorphic robotic systems are also known in which the articulated end effectors comprise anthropomorphic joints, such as the joints of the phalanges of a robotic hand, which are actuated by applying traction to actuation tendons.

[0008] The motor of the robotic system can be located upstream of the articulated end effector, and the actuation tendon is operatively connected to both the motor and the articulated end effector, the pose of the articulated end effector being determined by the motion of the motor of the robotic system transmitted by the actuation tendon.

[0009] The number of actuating tendons for multiple degrees of freedom of movement can vary, but typically two antagonistic tendons are connected to the same degree of freedom of an articulated end effector to move the articulated end effector in opposite directions.

[0010] Furthermore, for miniaturized articulated end effectors, the size and material of the actuation tendon become crucial in transmitting the motor's motion to the articulated end effector. In fact, as the scale decreases, it becomes increasingly important that the tendon undergoes precise longitudinal deformation (whether recoverable or not).

[0011] To facilitate miniaturization of articulated end effectors, it is possible to use polymer actuated tendons, as shown, for example, in International Publication WO 2022 / 137052 by the same applicant.

[0012] This type of actuated tendon reduces friction and diameter of the tendon, allowing movement over a very small connection radius.

[0013] Additionally, a small, articulating end effector is typically located at the distal end of a positioning shaft, which may be rigid, flexible, or articulating, allowing the actuating tendon to extend over a relatively long distance compared to the range of extension of the tendon along only the articulating end effector device at the distal end of the shaft.

[0014] During the operating phase, the tendons of the small articulating end effector are stressed under very large traction forces, which provides a gripping force suitable for clinical applications despite the small distal wrap radius of the tendon.

[0015] By having such long and thin tendons, the likelihood of longitudinal deformation of the tendon increases during the operating phase.

[0016] For example, in winch transmission systems, tendons are wound onto rotating spools and can cross or entangle during winding, which can increase localized friction and cause breakage when the motor motion is transmitted.

[0017] Similarly, when tendons are entangled, i.e., when they are intertwined within the extension of the shaft of a medical and / or surgical instrument, increased friction occurs locally, which affects transmission.

[0018] Furthermore, handheld surgical instruments can be used to grasp and cut tissue. The force required for the grasping action is provided by a motor via actuated tendons. The force provided by the motor, i.e., the force applied to the tendons when grasping, is much greater than the force used when not grasping. For example, in a specific instrument configuration such as that shown in commonly assigned International Publication WO 2022 / 137052 A1, each tip is actuated by two different tendons, one for each tip: a closed tendon and one for each tip.

[0019] When the tips are closed, the gripping force exerted by the tips on the object, provided by the motor thrust, acts on the two tendons, causing both tips to close. As a direct result, therefore, a significantly increased average force load is observed on the "closed" tendon.

[0020] Generally, all cords (or tendons) elongate when subjected to a load.

[0021] New or previously unstressed cords typically exhibit high elastic-plastic elongation when loaded. This is due, at least in part, to the slack in the fibers that make up the braided cord itself. For this reason, before installing a new cord into a surgical instrument, it is common to subject it to a high initial load to remove some of the residual plasticity from the stretching and braiding processes or the material itself.

[0022] In practice, braided cords usually have three elongation elements: (1) Elastic elongation deformation that recovers when the tensile load is stopped, and (2) Recoverable deformation, i.e., a relatively small deformation that gradually recovers over a period of time, which is often due to the braiding process, and which usually takes several minutes to a day to fully recover; (3) irreversible permanent elongation deformation; Includes:

[0023] It is understandable that the tendons used during closure and gripping are subjected to much higher average forces than other tendons, and therefore these tendons will undergo much larger or more pronounced recoverable and non-recoverable extensional deformations.

[0024] Therefore, during surgery, the surgical instrument may experience asymmetric extension between the closed tendon and the other tendons, and this difference, particularly between the closed and open tendons, may change the correspondence between the actuation piston and the tip orientation.

[0025] As the transmission tendon stretches, the motion transmitted by the motor to the articulating end effector of the surgical instrument differs, resulting in reduced efficiency and inconsistent operation. In effect, as the tendon stretches, some of the motion transmitted by the motor is not transmitted to the instrument due to the stretch in the tendon.

[0026] This inconvenience can also lead to reduced performance and maneuverability, in other words, a mismatch between the operation of the motor and the movement of the articulated end effector of the surgical instrument. Summary of the Invention [Problem to be solved by the invention]

[0027] To mitigate these problems, several known solutions propose adding sensors to the articulated end-effector, such as placing "encoder" type sensors at the joints or integrating Bragg fibers into the kinematic chain of the articulated end-effector to monitor its pose and orientation in real time.

[0028] Such detection of information about the pose of the articulated end effector does not completely solve the aforementioned problems because it requires the addition of additional sensor elements to the articulated end effector. The addition of additional sensor elements not only increases the size of the articulated end effector but also inevitably leads to imbalances in the weight and size distribution within the articulated end effector, which may pose design challenges. Furthermore, it may also impose mechanical constraints that limit the number and complexity of positions that the articulated end effector can actually reach during the motion phase.

[0029] This disadvantage is a significant obstacle to miniaturization of articulated end effectors.

[0030] Miniature articulated end effectors are in demand in the medical-surgical field, in the anthropomorphic robotics field, in microelectronics, micromechanics, precision mechanics, watchmaking, gems and costume jewelry, and in general in the automation field.

[0031] Particularly in the medical-surgical field, since the articulated end effector is a sterile component of the system and operates in a sterile field during the operational phase, it is often not possible or desirable to place an active sensor system on the articulated end effector so that the robotic system can detect the pose of the articulated end effector itself in real time.

[0032] At the same time, there is a strong movement in the field towards extreme miniaturization of articulated end effectors, which requires precise control over the position of the articulated end effector and the actions performed by the articulated end effector to ensure safety and ease of use.

[0033] In a teleoperated robotic system with a master-slave control architecture, motor movements are controlled based on user-provided movements to a master control device, which may take the form of a joystick, a mechanical appendage cantilevered from the master operating console, and may include an electromotive force feedback system that provides haptic feedback to the user based on information detected by a sensor system in the articulated end effector.

[0034] Teleoperated robotic systems are also known in which the master controller may be "ungrounded", i.e. not fixed to the ground, and therefore may not provide a haptic feedback system.

[0035] Therefore, there is a strong need in various fields to devise a solution that avoids installing a sensor system on the articulated end effector itself and ensures a more accurate correspondence between the motions imparted by the motors of the robotic system and the motions performed by the articulated end effector.

[0036] At the same time, there is a need to reduce the size of the articulated end effector of the robotic system without reducing control of the articulated end effector itself.

[0037] There is also a strongly felt need to optimize the control of small articulated instruments actuated by cables that undergo elastic-plastic deformation during use. [Means for solving the problem]

[0038] It is an object of the present invention to provide a method for controlling an articulated end effector actuated by an actuation tendon of a surgical instrument of a surgical robotic system, thereby at least partially overcoming the above-mentioned drawbacks of the prior art and, in particular, addressing the aforementioned needs felt in the art. Such an object is achieved by a method as set forth in claim 1.

[0039] Further embodiments of such a method are defined by claims 2 to 30.

[0040] It is a further object of the present invention to provide a surgical robotic system adapted to perform and / or be controlled by the aforementioned method. This object is achieved by a robotic system according to claim 31.

[0041] Further embodiments of such a robot system are defined by claims 32-57.

[0042] Such a method and such a robotic system provide a solution to the aforementioned technical problems.

[0043] In fact, the proposed solution makes it possible to generate a position control method for a motor (or pair of motors) of a robot manipulator intended to actuate a small articulated end effector, using a motion model of the operating conditions of the actuating tendons.

[0044] Information about the transmitted force can be detected by a load cell mounted on the motor that interfaces with the transmission unit.

[0045] For example, the transmission unit may comprise a rigid element, such as a piston, that interfaces with the motor, and an actuation tendon connected to the articulating end effector, the actuation tendon being rigidly connectable to the rigid element, e.g., glued to the piston, such that the force sensed at the interface between the motor and the rigid element of the transmission unit that is rigidly connectable to the actuation tendon is substantially equal to the traction force applied to the actuation tendon.

[0046] If the connection between the motor and the actuating tendon is not fixed, the method can take into account the yielding of the connection between the motor and the tendon.

[0047] Information about the motor movement is used to estimate in real time the force produced by the elastic extension of the actuated tendon and compared to the actual force read by the sensor. Comparing these two forces allows an estimation of the observed elasto-plastic extension of the tendon.

[0048] The proposed solution allows to ensure correspondence between the motor movement and the pose of the articulated end-effector, avoiding the need for additional sensors in the articulated end-effector and placing the sensors as "upstream" as possible to detect information useful for the control method, e.g., in medical-surgical applications, this allows to keep the sensors away from the sterile field.

[0049] When providing a teleoperated master-slave robotic system, the proposed solution helps to ensure correspondence between the motion of the master device and the pose of the articulated end effector of the slave device, minimizing tracking delay.

[0050] Importantly, the proposed solution makes it possible to compensate for the elastic-plastic mismatch between the motor motion and the pose of the articulated end-effector.

[0051] The proposed solution allows for the use of long, slender actuated tendons in a precise and controlled manner, which undergo high elastic-plastic deformations based on the forces applied by the motor.

[0052] The proposed solution allows to accurately estimate the current pose of the articulated end effector based on the detected forces applied to the transmission unit and using a model of the transmitted motion performed by the transmission unit.

[0053] Although the method according to the present invention is specifically adapted for controlling surgical robotic systems, it is not intended to control only surgical robotic systems, nor is the system to which it is adapted necessarily a master-slave robotic system.

[0054] The method according to the invention is adapted to control an anthropomorphic robotic system, which does not necessarily include a robotic phalange actuated by an actuation tendon.

[0055] Further characteristics and advantages of the method according to the invention will become apparent from the following description of preferred embodiments given by way of example and not of limitation, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0056] [Figure 1] 1 is an axonometric view showing a remote surgical robot system according to an embodiment; [Figure 2] Figure 1 shows an axonometric view of a portion of the telesurgery robotic system. [Figure 3] 1 is an axonometric view showing a distal portion of a robotic manipulator according to an embodiment. [Figure 4]FIG. 1 is an axonometric view of a surgical instrument according to an embodiment, in which tendons are shown schematically in dashed lines. [Figure 5] 1 illustrates an electric actuator, a transmission element, and a tendon of a surgical instrument, according to an embodiment. [Figure 6] FIG. 1 is an axonometric view, partially sectioned for clarity, of an articulating end effector of a surgical instrument according to an embodiment; [Figure 7] FIG. 1 illustrates a motor-piston-tendon assembly included in an embodiment of a robotic system of the present invention, with the motor and piston moved by a stroke Δx relative to the zero point in the absence of elastic-plastic elongation. [Figure 8] A simplified diagram illustrating the effect of elastic-plastic elongation Δl on the operation of the motor-piston-tendon assembly of FIG. [Figure 9] FIG. 1 illustrates a pair of antagonistic tendons of a motor-piston-tendon assembly that determine the rotational motion in one direction and the other of the end of a surgical instrument included in one embodiment of the robotic system of the present invention. [Figure 10] FIG. 1 shows a pair of two antagonistic tendons that determine the rotational movement of the ends of a surgical instrument, the antagonistic tendons including two ends and adapted to control the open and closed grasping / cutting degrees of freedom of the end effector of the surgical instrument. [Figure 11] FIG. 1 is a simplified diagram illustrating the structure and function of a portion of a robotic system (motor-piston-tendon-end effector assembly of a surgical instrument) according to one embodiment of the present invention. [Figure 12] FIG. 1 is a simplified diagram illustrating the structure and function of a portion of a robotic system (motor-piston-tendon-antagonist tendon pair of a surgical instrument end effector assembly) according to one embodiment of the present invention. [Figure 13] 1 illustrates an embodiment of a method and system according to the present invention. [Figure 14] Diagram showing some details about the typical behavior of an actuated tendon using an exemplary "strain-stress" curve. DETAILED DESCRIPTION OF THE INVENTION

[0057] 1-14, a method for controlling an articulated end effector 40 actuated by one or more actuation tendons of a surgical instrument 20 of a surgical robotic system is described.

[0058] The articulated end effector is also referred to below as an "articulated end device" or "end effector."

[0059] Advantageously, the method can be performed during the operating phase of the surgical instrument.

[0060] The method is applied to a surgical instrument (20) that includes an articulating end effector (40) and at least one actuation tendon (31, 32, 33, 34, 35, 36) configured to actuate the articulating end effector (40).

[0061] The method is applied to a surgical robotic system that, in addition to the surgical instrument 20, comprises a control means 9 and at least one electric actuator 11, 12, 13, 14, 15, 16. The electric actuators 11, 12, 13, 14, 15, 16 are operatively connected to the at least one actuation tendon 31, 32, 33, 34, 35, 36, respectively, and are configured to impart a movement to the respective actuation tendon that is controlled by the control means 9. This determines a unique correlation between a movement of at least one of the one or more electric actuators 11, 12, 13, 14, 15, 16 and a movement of at least one of the articulated end effectors 40.

[0062] In the method, during the aforementioned operating phase, when at least one electric actuator 11, 12, 13, 14, 15, 16 is in contact with at least one actuating tendon 31, 32, 33, 34, 35, 36, respectively, the following steps are performed.

[0063] The method, in the aforementioned operational steps, a known stroke and / or a known position Δ given by the control means 9 to the at least one electric actuator 11, 12, 13, 14, 15, 16 relative to a reference zero position; x and / or as a function thereof, a desired target force F(Δ) related to the predicted elastic elongation of at least one actuated tendon 31, 32, 33, 34, 35, 36. x ) and Detecting an actual force F exerted by at least one of the at least one electric actuators 11, 12, 13, 14, 15, 16 on a corresponding at least one of the at least one actuating tendons 31, 32, 33, 34, 35, 36; The detected actual force F and the desired target force F(Δ x ) based on the difference between the length change Δ due to plastic elongation or elastic-plastic elongation of at least one of the actuating tendons 31, 32, 33, 34, 35, 36 l estimating and / or calculating Perform steps including:

[0064] Finally, the method uses the estimated and / or calculated length change Δ l as a correction input (in particular an elastic-plastic correction) for controlling at least one electric actuator 11, 12, 13, 14, 15, 16.

[0065] It should be noted that the aforementioned technical effect of reducing or canceling errors caused by elastic elongation includes or corresponds to "correcting" such errors and / or "minimizing" such errors.

[0066] As used herein, the term "elastoplastic elongation" refers to recoverable elongation deformations (i.e., relatively small deformations that recover gradually over a period of time, typically varying from a few minutes to a day before full recovery) and / or irrecoverable permanent elongation deformations (strictly speaking, "plastic deformations").

[0067] Thus, the plastic or elastoplastic deformations corrected by this method are deformations that do not recover immediately when the tensile load is stopped.

[0068] Therefore, the above definition of "elastic-plastic elongation" excludes only elastic deformation (deformation that recovers immediately when the tensile load is removed) from all possible deformations.

[0069] According to one embodiment of the method, the aforementioned step of detecting the actual force F is performed by detecting the aforementioned known stroke and / or known position Δ of the at least one electric actuator 11, 12, 13, 14, 15, 16. x and detecting an instantaneous actual force Ft applied by at least one electric actuator 11, 12, 13, 14, 15, 16 at a time corresponding to the time at which the predicted elastic force is estimated.

[0070] According to an implementation option of such an embodiment, the elastic-plastic length change Δ l The aforementioned step of estimating and / or calculating the elasto-plastic length change Δ l This includes calculating

[0071]

number

[0072] where k plis the elastic modulus according to the simplified model representing elongation, and α is a parameter related to the elastic-plastic correction function.

[0073] According to the given implementation options, k pl is equal to k, i.e., the known elastic modulus of at least one tendon, and α is equal to −1. In this case, we obtain

[0074]

number

[0075] According to one embodiment of the method, the aforementioned step of detecting the actual force F is performed by detecting the aforementioned known stroke and / or known position Δ of at least one actuating tendon 31, 32, 33, 34, 35, 36. x and detecting an instantaneous actual force F(t-1) applied by at least one electric actuator 11, 12, 13, 14, 15, 16 at a known time interval before the time at which the predicted elastic force is estimated.

[0076] According to one embodiment of the method, said controlling of at least one electric actuator comprises controlling the position of at least one electric actuator 11, 12, 13, 14, 15, 16, said position control being based on a change in length Δ of at least one actuated tendon due to an elastic-plastic elongation of the actuated tendon. l , which involves applying a movement to at least one electric actuator 11, 12, 13, 14, 15, 16 in consideration of an estimate of the force F(t) acting on the articulated end effector 40 and the desired nominal force of the articulated end effector 40, as described above, due to the elastic-plastic length change Δ l It is possible to reduce or cancel the error caused by

[0077] According to an implementation option, the aforementioned position control is performed by calculating an estimated and / or calculated length change Δ lThe corrected kinematic zero position P is calculated by adding the value of 0-mod This includes defining

[0078]

number

[0079] According to an embodiment, the aforementioned steps of the method are carried out iteratively in a discrete sequence of steps of estimating, in particular, the length change Δ due to plastic or elasto-plastic elongation of the actuated tendon at time t. l (t) is calculated based on the actual force F(t-1) detected at the previous time.

[0080] According to an implementation option, the step of detecting the force Fm is performed dynamically at discrete detection times with predefined detection and control frequencies.

[0081] According to an implementation option of the aforementioned embodiment, the position of at least one electric actuator at time t is determined by a corrected kinematic zero position P 0-mod or the initial reference kinematic zero position P0 and the length change Δ due to plastic or elasto-plastic elongation of the actuated tendon l (t) and the instantaneous position of the electric actuator Δ x It is calculated as a function of (t) according to the following series of equations:

[0082]

number

[0083] According to one embodiment, the method is applied to a master-slave system in which, depending on the control mode, the surgical instrument is a slave device controlled by a master device of the robotic system, and in the absence of external forces, the method can minimize the error between the pose controlled by the master device and the pose reached by the articulated end effector 40 of the slave device within a finite time.

[0084] According to one embodiment, the method is applied to a robotic system in which a surgical instrument 20 comprises a plurality of actuating tendons 31, 32, 33, 34, 35, 36 and a plurality of electric actuators 11, 12, 13, 14, 15, 16 respectively.

[0085] According to such an embodiment, the method comprises: x the aforementioned step of estimating the actual force F is performed with reference to a plurality or all of the actuated tendons 31, 32, 33, 34, 35, 36; the aforementioned step of detecting the actual force F is performed with reference to a plurality or all of the electric actuators 11, 12, 13, 14, 15, 16; and the length change Δ due to the plastic or elasto-plastic elongation of the actuated tendons. l the aforementioned steps of estimating and / or calculating are performed with reference to a plurality or all of the electric actuators 11, 12, 13, 14, 15, 16, and the length change Δ l for position control are performed with reference to several or all of the electric actuators 11, 12, 13, 14, 15, 16.

[0086] Depending on the possible mounting options, the length change (Δ l ) can be estimated based on a linear model or on a more complex nonlinear model.

[0087] According to one embodiment, particularly the embodiment shown in Figures 9 to 12, the method is applied to a robotic system in which the master device of the robotic system is a handheld, unconstrained master device configured to be moved and manipulated by an operator according to degrees of freedom associated with opening, closing, and / or cutting the grip of the slave surgical instruments.

[0088] Each of the one or more actuating tendons 31, 32, 33, 34, 35, 36 is operably connected to both a respective electric actuator of the robotic surgical system and to the articulated end effector 40, and actuates a respective one or more degrees of freedom of the articulated end effector 40.

[0089] The aforementioned actuating tendons 31, 32, 33, 34, 35, 36 comprise one or more antagonistic tendon pairs, for example two antagonistic tendon pairs configured to respectively control the opening, closing and / or cutting of the grasp performed by the two tips or ends or tweezers 43, 44 of the articulating end effector 40 of the surgical slave instrument.

[0090] According to such an embodiment, the method comprises: l The aforementioned step of using the tendons in the antagonistic tendon pair as corrective inputs for controlling the gripping degree of freedom is performed with reference to the tendons in the antagonistic tendon pair, thereby controlling the gripping degree of freedom and / or the cutting degree of freedom.

[0091] According to one embodiment, this method is carried out only during the grasping sub-phase of the two tips or tweezers or ends 43, 44 during the aforementioned operating phase of the surgical instrument.

[0092] According to an implementation option of such an embodiment, during the operation phase of the surgical instrument, the orientation and opening and closing of the articulated end effector 40 of the surgical instrument are position-controlled, with elastic-plastic compensation being enabled only during the aforementioned grasping sub-phase, and the correction contribution of the elastic-plastic compensation being added to the position control.

[0093] According to an embodiment, the method further comprises calculating and performing in real time an elastic correction of the elastic extension experienced by the at least one actuated tendon, where either an elasto-plastic correction or an elastic correction or both are performed and applied. The position control is performed by calculating the corrective contribution due to the elastic correction (Δx e ) and the correction contribution due to elastic-plastic correction (Δx ep ) together determine the compensated position (X(t)) added to the nominal position (Xc).

[0094]

number

[0095] According to one embodiment, the method includes performing subsequent corrections at a series of subsequent times during an operational phase of the surgical instrument, the subsequent corrections being additive over time during the operational phase and being non-recoverable.

[0096] Depending on the implementation options, both elasto-plastic and elastic corrections are implemented and applied simultaneously.

[0097] In another implementation option, the elastic and elasto-plastic corrections are applied in different configurations, with either one being enabled or disabled, in which case the correction contribution from the temporarily disabled (elastic or elasto-plastic) correction remains fixed and is then updated when that correction is enabled.

[0098] According to an implementation, when a closing force is recognized during the operating phase, elastic-plastic compensation control of the actuator closing the articulated end effector is enabled and elastic compensation control is disabled.

[0099] According to an embodiment, the method determines the respective nominal stroke Δ at which the tip or end of the articulated end effector 40 is expected to contact and lock the grasping and / or cutting degrees of freedom. x,j and actuating the powered actuators associated with the tendons in the antagonistic tendon pair in accordance with

[0100] Furthermore, in such a case, the step of estimating the desired target force may be performed by calculating the nominal stroke Δ x,j Desired target force F(Δ x,j ) is estimated.

[0101] The aforementioned step of detecting the actual force F includes determining the target actual force F based on the actual force applied by the activated one or more electric actuators.

[0102] At least one length change Δ l The aforementioned step of estimating and / or calculating the length change Δ due to plastic or elasto-plastic elongation of the tendons included in the antagonistic tendon pair is based on the respective predicted elastic forces and the determined target actual force F. l,j This includes calculating

[0103] The step of controlling the position of at least one electric actuator includes controlling the electric actuator associated with the tendon in the antagonistic tendon pair to reach the target actual force F.

[0104] According to an implementation option, the aforementioned step of determining the target actual force F includes determining the arithmetic mean of the forces detected at two of the aforementioned antagonist tendons as the target actual force F.

[0105] According to another implementation option, the step of determining the target actual force F includes determining the maximum force among the forces detected at two of the antagonist tendons as the target actual force F.

[0106] According to another implementation option, the method steps are performed iteratively, and the step of determining the target actual force F comprises determining as the target actual force F a time average of the actual forces detected at two of the antagonist tendons at at least two previous times.

[0107] According to a specific embodiment, the aforementioned step of determining the target's actual force F(t-1) at time t-1 is performed by one of the following equations:

[0108]

number

[0109]

number

[0110]

number

[0111]

number

[0112] where y is an index representing time, and F1 and F2, F3 and F4 represent the actual forces detected at the two antagonistic tendon pairs.

[0113] According to an embodiment, the method calculates a corrected kinematic zero position P for the gripping and / or cutting control based on the stroke and / or position of the electric actuator at a target actual force F. 0-mod and further defining:

[0114] Advantageously, this embodiment allows for a consistent closing / cutting force / torque to be delivered each time the tip or end of the end effector of the surgical instrument is closed / cut by compensating for errors due to non-recoverable or very slowly recovering elongation of the tendon, which is desirable because such closing / cutting force / torque can be repeatedly achieved without interrupting remote operation to allow the tendon to recover.

[0115] The above-described calibration of robotic systems and surgical tools is also useful, for example, when gripping or cutting a surgical needle with the same force (in this case, the closure / cutting force / torque is a cutting force that must not exceed a threshold, otherwise the blade may slip).

[0116] As noted above, it is important to note that the optimal closing / cutting force / torque values ​​to be delivered are unknown and are not actually measured in real time at the end effector of the surgical instrument. This method embodiment ensures that the closing / cutting force / torque remains constant at each closing or cutting event because it compensates for errors due to tendon lengthening, or possibly shortening (in which case the motor backs off to compensate, reducing the force to achieve the expected target force) at each closing or cutting event.

[0117] According to an implementation option, the method further comprises estimating the elastic modulus of the one or more tendons as a function of time, k(t).

[0118] According to another implementation option, this method step is applied only if the target actual force F takes a value within a predefined range of values ​​that are considered acceptable.

[0119] According to one embodiment of the method, the aforementioned steps of detecting the forces exerted by the electric actuators 11, 12, 13, 14, 15, 16 are performed by respective force or torque sensors operatively connected to the respective electric actuators.

[0120] According to one embodiment, this method is applied when the aforementioned surgical instrument 20 further comprises at least one transmission element 21, 22, 23, 24, 25, 26 (e.g., a piston), which is operably connected to a corresponding at least one actuating tendon 31, 32, 33, 34, 35, 36 and operably connectable to a corresponding electric actuator 11, 12, 13, 14, 15, 16.

[0121] Thus, in such cases, the surgical instrument comprises a plurality of "transmission units", each unit including an actuating tendon and a piston, and in each unit, preferably, the tendon is fixed to the piston, and the respective electric actuator is actuated by imparting movement to the piston of the transmission unit.

[0122] According to an implementation option, the surgical instrument comprises six transmission units, namely six tendons, six electric actuators and six pistons.

[0123] According to the implementation option, each transmission unit (i.e. each motor-piston-tendon chain) is managed separately.

[0124] According to another implementation option, the antagonistic transmission units (and antagonistic tendons) are managed in pairs.

[0125] According to one embodiment of this method, the length change correction parameters are determined in a controlled and variable manner depending on the pose of the articulated end effector 40 to account for different frictions associated with different poses.

[0126] According to one embodiment of the method, said actuating tendon is a polymer tendon, preferably formed from braided polymer fibers.

[0127] Referring again to Figures 1 to 14, the surgical system described herein comprises a surgical instrument 20, a control means 9, at least one actuating tendon 31, 32, 33, 34, 35, 36, and at least one electrically powered actuator 11, 12, 13, 14, 15, 16.

[0128] The surgical instrument 20 includes an articulating end effector 40 .

[0129] At least one actuation tendon 31 , 32 , 33 , 34 , 35 , 36 is configured to actuate the articulated end effector 40 .

[0130] At least one electric actuator 11, 12, 13, 14, 15, 16 is operatively connectable to each of said at least one actuating tendon 31, 32, 33, 34, 35, 36 and configured to impart a movement to the respective actuating tendon that is controlled by the control means 9, thereby determining a unique correlation between at least one movement of one of the one or more electric actuators 11, 12, 13, 14, 15, 16 and a corresponding at least one movement of the articulated end effector 40.

[0131] The control means 9 of the robot system is configured to perform the following actions when at least one electric actuator 11, 12, 13, 14, 15, 16 is in contact with at least one actuating tendon 31, 32, 33, 34, 35, 36, respectively, during the operating phase of the robot system:

[0132] The control means 9 of the robot system, during the operation stage of the robot system, a known stroke and / or a known position Δ given by the control means 9 to the at least one electric actuator 11, 12, 13, 14, 15, 16 relative to a reference zero position; x and / or as a function thereof, a desired target force F(Δ) related to the predicted elastic elongation of at least one actuated tendon 31, 32, 33, 34, 35, 36.x ) and - detecting an actual force F exerted by at least one of said at least one electric actuator 11, 12, 13, 14, 15, 16; The detected actual force F and the desired target force F(Δ x ) based on the difference between the length change Δ due to plastic elongation or elastic-plastic elongation of at least one of the actuating tendons 31, 32, 33, 34, 35, 36 l estimating and / or calculating is configured to execute

[0133] The control means 9 of the robot system controls the length change Δ l Taking into account the estimated value of the aforementioned estimated and / or calculated length change Δ l as a corrective input for controlling at least one electric actuator 11, 12, 13, 14, 15, 16.

[0134] According to one embodiment, the robotic system is a master-slave system and the surgical instrument is a slave device that is controlled by the master device of the robotic system depending on the control mode.

[0135] In such a case, the control means 9 of the robotic system is configured to control the system such that, in the absence of external forces, the error between the pose commanded by the master device and the pose reached by the articulated end effector 40 of the slave device is minimized within a finite time.

[0136] According to one embodiment of the robotic system, the surgical instrument 20 comprises a plurality of actuating tendons 31, 32, 33, 34, 35, 36 and the surgical robotic system comprises a corresponding plurality of powered actuators 11, 12, 13, 14, 15, 16.

[0137] In such cases, depending on several possible implementation options: Desired target force F(Δ xThe above operations of estimating ) are performed with reference to several or all of the actuated tendons 31, 32, 33, 34, 35, 36. The above-described operation of detecting the actual force F is performed for several or all of the electric actuators 11, 12, 13, 14, 15, 16. Length change Δ l The above operations of estimating and / or calculating are performed with reference to several or all of the electric actuators 11, 12, 13, 14, 15, 16. Length change Δ l The above operations using as a corrective input are performed with reference to several or all of the electric actuators 11, 12, 13, 14, 15, 16.

[0138] According to one embodiment of the robotic system, the master device of the robotic system is a handheld, untethered master device configured to be moved by an operator and manipulated by the operator with degrees of freedom associated with opening, closing, and / or cutting the grip of the surgical slave instruments.

[0139] Furthermore, each of the one or more actuating tendons 31, 32, 33, 34, 35, 36 is operatively connected to both a respective electric actuator of the robotic surgical system and the aforementioned articulated end effector 40 to actuate a corresponding one of the one or more degrees of freedom of the articulated end effector 40.

[0140] Furthermore, the aforementioned actuating tendons 31, 32, 33, 34, 35, 36 may comprise one or more antagonistic tendon pairs, for example consisting of two antagonistic tendon pairs, which are configured to control the opening / closing degrees of freedom of the grasping and / or cutting degrees of freedom performed by the two tips or ends or tweezers 43, 44 of the articulated end effector 40 of the surgical slave instrument, respectively.

[0141] In such an embodiment, the change in length Δ las a corrective input are performed with reference to the tendons in the antagonistic tendon pair, thereby controlling the grasping and / or cutting degrees of freedom.

[0142] According to the implementation options of the robot system, the control means 9 may determine the respective nominal stroke Δ at which the tip or end of the articulated end effector 40 is expected to contact and lock the grasping and / or cutting degrees of freedom. x,j and further configured to actuate the electric actuators associated with the tendons in said antagonistic tendon pair in accordance with

[0143] Furthermore, in such cases, The operation of estimating the desired target force is carried out by calculating the nominal stroke Δ x,j Desired target force F(Δ x,j ) is estimated. The act of detecting the actual force F includes determining the target actual force F based on the actual force applied by the one or more actuated electric actuators. At least one length change Δ l The operation of estimating and / or calculating the length change Δ due to plastic elongation or elasto-plastic elongation of the tendons included in the antagonistic tendon pair is based on the respective predicted elastic forces and the determined target actual force F. l,j This includes calculating The operation of controlling the position of the at least one electric actuator includes controlling the electric actuator associated with the tendon in the antagonistic tendon pair to reach the target actual force F as described above.

[0144] According to one embodiment, the robotic system is a microsurgery teleoperated robotic system and the surgical instrument is a microsurgical instrument.

[0145] According to a possible embodiment, a robotic system is configured to perform and / or be controlled by a method according to any of the aforementioned method embodiments.

[0146] Referring again to FIGS. 1 to 14, the operating principles and some specific embodiments of the method and system according to the present invention will now be described in further detail, by way of non-limiting example.

[0147] As shown in Figure 7, the system includes a motor acting on a piston connected to one end of a tendon that slides freely on a pulley, while the opposite end of the tendon is blocked.

[0148] The motor and piston can move linearly along the same axis. A sensor (e.g., a load cell) is attached to the motor to measure the contact force between the motor and the piston.

[0149] Let us first assume that the motor contacts the piston at position P0 (which denotes the initial position of the motor in contact with the piston) and exerts a null force F=0.

[0150] Assuming that the tendon is modeled as an ideal spring (massless, with negligible thickness when fully compressed, and without friction or other dissipative phenomena), applying a motion offset (i.e., stroke) Δx applied by the motor will result in a change in tension according to Hooke's Law. The elastic force of a spring stressed in traction or compression in the longitudinal direction along TIFF2026501603000011.tif64 is expressed by the following formula:

[0151]

number

[0152] Therefore, the force F with which the spring reacts to the stress is the extension of the spring Δ x(i.e., the elongation of the tendon in this case) e represents the longitudinal elastic modulus of the spring (tendon) and is expressed in [N / m].

[0153] Now, considering only the elastic component of the tendon, when the motor returns to position P0, the piston contacts the motor with a force F=0.

[0154] Therefore, if the tendon can be modeled by Hooke's law, the motor acts on the piston and for any resulting motion acting on the tendon, there will be the same contact force between the motor and the piston.

[0155] In fact, due to the dissipative deformation effect, repeated application of the same movement to the tendon (by the action of the corresponding pistons controlled by the respective motors) leads to deformation of the tendon, in particular to elongation that cannot be instantly recovered.

[0156] This effect results in the piston being at a different position P1 (see Figure 8) when the motor returns to the initial position P0 at time t. The extension at time t is therefore defined as:

[0157]

number

[0158] If the motor movement does not take this amount into account, the same movement (or stroke) Δ x , the force available at the end of the travel will be lower than the force available before the tendon deformation. Because part of the motor movement is used to cover the distance range that brings the motor into contact with the piston (as shown in Figure 8), the final extension of the tendon results in a lower tension being applied to the tendon.

[0159] If Hooke's Law and a constant modulus of elasticity over time are considered valid, Hooke's Law can be used to estimate the tendon elongation, since the force generated while the motor is moving is known in advance when the load cell reads a value greater than 0, indicating that the motor is in contact with the piston.

[0160] As a result, the tendon elongation at any time t in the motor's movement when contact with the piston occurs can be estimated by the following equation:

[0161]

number

[0162] According to the implementation options already explained above, the method inserts an additional displacement of the motor to compensate for the previously calculated elongation. The new zero position of the motor is therefore defined by the following formula:

[0163]

number

[0164] Therefore, the elongation Δ l is the motor movement required to maintain contact with the piston with zero force F=0.

[0165] To reiterate, the position of the motor at time t is given by the equation already mentioned above:

[0166]

number

[0167] Information about the applied forces is used to estimate the elastic-plastic elongation of the actuated tendons in real time.

[0168] When using an articulated end effector, the tendon is connected to a rotary joint rather than a fixed terminal (as exemplified in Figure 9).

[0169] In such an embodiment, the system converts linear motion generated by the motor into rotational motion of the terminal member.

[0170] When the piston deviates from the zero position, the correspondence between the linear displacement and the position of the end member is no longer valid. The extension of the tendon causes the piston to move from its initial position, which makes the piston-motor system have a zero kinematic correspondence. Therefore, it is very important to compensate for the extension of the tendon.

[0171] Consider now an embodiment in which the end effector of the surgical instrument is constituted by two tips or ends or forceps 43, 44 as shown in FIG.

[0172] The two tips or ends or tweezers are movable on a rotary joint, are coaxial, and are actuated by two independent motor-piston-tendon assemblies, as shown in Figure 12. In such a case, the two tips or ends or tweezers are free to rotate but are coaxially positioned so that they can close over one another.

[0173] Assuming that rotational friction is zero, or in any case negligible, when the tip rotates freely the load cell will read zero force and there will be no elongation of the tendon.

[0174] As shown in Figures 10 and 12, when the two tips (or ends of the tweezers) overlap, a closing force can be applied created by the movement of two motors that rotate the two tips or ends inward.

[0175] In other words, in such cases, the motor's motion is completely converted into a force exerted by one end on the other. The motor transmits the force exerted by the tendon according to Hooke's law. The same law as described in the previous paragraph allows for the introduction of an extension recovery offset.

[0176] Depending on the implementation option, this occurs independently in two "motor-piston-tendon-tip" assemblies.

[0177] Now, when modeling the dynamic case with internal mechanical friction, one end transmits a force to the other end due to contact, so it is necessary to consider that the degrees of freedom do not exist independently of each other.

[0178] Due to the internal geometry of the surgical instrument, in accordance with this embodiment and the above assumptions, the motor motion, and therefore the applied force, is partially transferred between one degree of freedom and another.

[0179] According to implementation options, the combination of forces applied by different motors can be considered as a good approximation and a good index of the force F(t-1) contained in the equation shown above and is effective for the extension recovery of one or more tendons.

[0180] Such an index can be used as a proportional expression of the force applied between the tips.

[0181] In the system shown in Figure 10, the lower extremity is actuated by tendon 1 when "open" and tendon 2 when "closed." The upper extremity is actuated by tendon 3 when "closed" and tendon 4 when "open."

[0182] Depending on the different implementation options, the force combination used as the force F(t-1) is expressed by one of the following formulas (the force subscripts refer to the exemplary numbering of the tendons described above):

[0183]

number

[0184]

number

[0185]

number

[0186]

number

[0187] In another embodiment, the above method is implemented as shown in FIG.

[0188] In such a case, the position control of the articulated end effector includes an elastic compensation controller and an elastic-plastic compensation controller.

[0189] It should be noted that several elasticity compensation controllers (not the subject of this patent application) can be used.

[0190] For example, according to an implementation option of the embodiment shown in FIG. 13, the elastic compensation controller can operate based on an elastic stretch compensation method described in the following steps.

[0191] - detecting a force exerted by at least one of said one or more electric actuators 11, 12, 13, 14, 15, 16 during an operating phase of the surgical instrument; Based on the detected force Fm, a length change of at least one of the one or more actuated tendons 31, 32, 33, 34, 35, 36 due to elastic extension of the actuated tendon is estimated by a predefined mathematical model, and the estimated length change is used to control the position of the one or more electric actuators 11, 12, 13, 14, 15, 16.

[0192] Such position control involves imparting movement to said at least one electrically operated actuator 11, 12, 13, 14, 15, 16 to account for the estimated change in length of at least one actuating tendon 31, 32, 33, 34, 35, 36 to reduce or cancel the error caused by elastic stretching between the position reached by the articulated end effector 40 and the desired nominal position of the articulated end effector 40. The desired nominal position refers here to elastic correction only and may, for example, be the position that would be obtained in the absence of elastic stretching.

[0193] According to an embodiment of the elasticity controller, the aforementioned steps of using the estimated length change in position control and imparting movement to the respective electric actuators are performed based on the following equation:

[0194]

number

[0195] Such formulas are specific to each electric actuator and therefore determine the specific control of each electric actuator.

[0196] In the above equation, Fm is the sensed force, u is the position controlled by the electric actuator, Kel is the elastic modulus of the actuating tendon, and Ω is a multiplicative parameter.

[0197] Returning to Figure 13, it should be noted that the elastic position controller and the elastic-plastic force controller are configured to act in parallel on the position control (when enabled) to overcome deformations of the tendon during the operating phase when the tendon is under stress.

[0198] The elastic and elasto-plastic controllers can be used in different configurations by enabling or disabling their operation, providing different correction contributions. During the phase of operation when a controller is disabled, its absolute contribution remains fixed and is updated the next time it is enabled.

[0199] Depending on the implementation options, the elasto-plastic controller is used complementary to the elastic controller. For example, if a closing force is detected during the operating phase, the elasto-plastic compensation control of the closing motor is activated and the elastic compensation control is deactivated. In fact, maintaining the elastic compensation is deactivated, since it works against the target value of the force required when closing the tip. This maintains the closing force (e.g., the force according to the formula above) that is used as the basis for the deformation calculation.

[0200] The elastic-plastic compensation allows for a constant gripping force to be maintained and prevents displacement due to tendon elongation during use.

[0201] Another implementation option involves operating according to the above implementation option, except that the elastoplastic controller is disabled only at the closure tendons.

[0202] Referring to FIG. 14, a more detailed description of the typical behavior of an actuating tendon (and the material from which it is made) is provided by a "strain-stress" curve.

[0203] In the curves shown in FIG. 14, the following phases are highlighted: (1) Elastic phase, (2) a plastic phase, in which forces no longer act elastically; (3) A return phase operating in such a way as to approach the elastic mode (according to the method of the present invention, such a phase already includes a position offset determined by the control described above). (4) A further moving phase is first developed along the elastic curve and then, when a greater force / stress is applied by the control, continues in the part of the curve corresponding to the plastic region.

[0204] From the foregoing, it will be appreciated that the objects of the present invention are fully achieved by the above-described method and system in accordance with the features detailed above and broadly disclosed in the preceding section, "Summary of the Invention."

[0205] Those skilled in the art can make changes and adaptations to the above method embodiments and substitute functionally equivalent elements for other elements to meet their foreseeable needs without departing from the scope of the claims. Each feature described above as belonging to a possible embodiment can be implemented independently of other embodiments.

Claims

1. 1. A method for controlling an articulated end effector (40) actuated by one or more actuation tendons of a surgical instrument (20) of a robotic surgical system, the method being performed during an operating phase of the surgical instrument, the method comprising: The surgical instrument (20) comprises an articulated end effector (40) and at least one actuation tendon (31, 32, 33, 34, 35, 36) configured to actuate the articulated end effector (40); the robotic surgical system includes: The surgical instrument (20); Control means (9); at least one electric actuator (11, 12, 13, 14, 15, 16) operably connectable to each of the at least one actuating tendon (31, 32, 33, 34, 35, 36) and configured to impart a movement to each actuating tendon controlled by the control means (9), the at least one electric actuator (11, 12, 13, 14, 15, 16) determining a respective unambiguous correlation between at least one movement of the one or more electric actuators (11, 12, 13, 14, 15, 16) and at least one movement of the articulated end effector (40); Equipped with The method comprises, during the operating stage, when at least one of the electric actuators (11, 12, 13, 14, 15, 16) is in contact with at least one of the actuating tendons (31, 32, 33, 34, 35, 36), A control means (9) provides at least one of the electric actuators (11, 12, 13, 14, 15, 16) with a respective known stroke and / or known position (Δ ｘ ) and / or at each known stroke and / or known position (Δ ｘ a desired target force (F(Δ)) related to the predicted elastic elongation of at least one of said actuated tendons (31, 32, 33, 34, 35, 36) as a function of ｘ ) estimating detecting an actual force (F) exerted by at least one of the at least one electrically-driven actuators (11, 12, 13, 14, 15, 16) on one of the corresponding at least one actuating tendons (31, 32, 33, 34, 35, 36); The detected actual force (F) and the desired target force (F(Δ ｘ )) based on the difference between the length change (Δ ｌ estimating and / or calculating The estimated and / or calculated length change (Δ ｌ ) as a corrective input for controlling at least one of said electric actuators (11, 12, 13, 14, 15, 16); performing the steps including: method.

2. The step of detecting the actual force (F) is carried out by using the known stroke and / or known position (Δ ｘ Detecting an instantaneous actual force (F(t)) applied by at least one of the electric actuators (11, 12, 13, 14, 15, 16) at a time corresponding to the time when a desired target force is estimated. The method of claim 1.

3. The change in length (Δ ｌ The step of estimating and / or calculating the change in length (Δ) due to plastic or elasto-plastic elongation of the actuated tendon may be performed using the following equation: ｌ ), [Equation 1] Here, k ｐｌ is the elastic modulus according to the simplified model representing elongation, and α is a parameter related to the elastic-plastic correction function. The method of claim 2.

4. The step of detecting the actual force (F) may be performed by detecting the known stroke and / or known position (Δ ｘ Detecting an instantaneous actual force (F(t-1)) applied by at least one of the electric actuators (11, 12, 13, 14, 15, 16) at a known time interval prior to the time at which the desired target force is estimated. The method of claim 1.

5. The control of the at least one electric actuator includes position control of the at least one electric actuator (11, 12, 13, 14, 15, 16); The position control is The change in length (Δ) of at least one of the actuated tendons due to plastic elongation or elastic-plastic elongation of the at least one actuated tendon. ｌ ), to impart movement to at least one of the electric actuators (11, 12, 13, 14, 15, 16) to determine the change in length (Δx) between the force F(t) exerted on the articulated end effector and the desired nominal force F(Δx) of the articulated end effector. ｌ ) reducing or cancelling errors caused by 5. The method according to any one of claims 1 to 4.

6. The position control is The estimated and / or calculated length change (Δ l ) is set to the initial reference kinematic zero position (P ０ ) to obtain the corrected kinematic zero position (P ０－ｍｏｄ ), [Equation 2] The method of claim 5.

7. The steps of the method are carried out iteratively in a discrete sequence of steps to estimate, in particular, the length change (Δ ｌ (t)) is calculated based on the actual force F(t-1) detected at the previous time, 7. The method according to any one of claims 4 to 6.

8. The position of at least one of the electric actuators at time t is calculated by the corrected kinematic zero position (P ０－ｍｏｄ ) or as a function of the initial reference kinematic zero position (P ０ ) and the length change due to plastic or elasto-plastic elongation of the actuated tendon (Δ ｌ (t)) and the instantaneous position (Δ ｘ (t)) according to the following formula: [Equation 3] The method of claim 7.

9. the robotic surgical system is a master-slave system, and the surgical instrument is a slave device controlled by a master device of the robotic surgical system according to a control mode; The method allows minimizing, in a finite time, the error between the pose commanded by the master device and the pose reached by the articulated end effector (40) of the slave device in the absence of external forces.

9. The method according to any one of claims 1 to 8.

10. the surgical instrument (20) comprises a plurality of actuating tendons (31, 32, 33, 34, 35, 36), and the robotic surgical system comprises a corresponding plurality of electrically powered actuators (11, 12, 13, 14, 15, 16); The desired target force (F(Δ ｘ ) is performed with reference to several or all of the actuated tendons (31, 32, 33, 34, 35, 36), the step of detecting the actual force (F) is performed for a plurality or all of the electric actuators (11, 12, 13, 14, 15, 16); The length change (Δ ｌ ) is performed with reference to several or all of the electric actuators (11, 12, 13, 14, 15, 16), The estimated and / or calculated length change (Δ ｌ ) as a corrective input for controlling is performed with reference to several or all of the electric actuators (11, 12, 13, 14, 15, 16), 10. The method according to any one of claims 1 to 9.

11. the master device of the robotic surgical system is a handheld, unconstrained master device adapted to be moved by an operator and manipulated by the operator with degrees of freedom associated with opening, closing, and / or cutting the grasp of the surgical slave instruments; each of the one or more actuation tendons (31, 32, 33, 34, 35, 36) is operatively connected to both the respective electric actuators and the articulated end effector (40) of the robotic surgical system to actuate a respective degree of freedom of the one or more degrees of freedom of the articulated end effector (40); said actuating tendons (31, 32, 33, 34, 35, 36) comprise one or more pairs of antagonistic tendons, configured to control, for example, opening, closing and / or cutting, respectively, the grasping performed by the two tips or tweezers or ends (43, 44) of the articulated end effector (40) of the slave surgical instrument; The estimated and / or calculated length change (Δ ｌ ) as a corrective input for controlling the tendon of the antagonistic tendon pair, thereby controlling the gripping degree of freedom of opening, closing, and / or cutting.

11. The method according to claim 9 or 10.

12. the method being carried out only during the sub-step of grasping the two tips or tweezers or ends (43, 44) during the operating step of the surgical instrument, The method of claim 11.

13. During the operating phase of the surgical instrument, the orientation and opening and closing of the articulated end effector (40) of the surgical instrument are position-controlled; the elastic-plastic correction is activated only during the grasping sub-phase, and the correction contribution of the elastic-plastic correction is added to the position control. The method of claim 12.

14. further comprising calculating and performing in real time an elastic correction for the elastic elongation experienced by at least one of the actuated tendons; Either or both of the elasto-plastic correction and the elastic correction are performed and applied, and the position control is performed based on the correction contribution of the elastic correction (Δx ｅ ) and the correction contribution due to elastic-plastic correction (Δx ｅｐ ) together determine the compensated position (X(t)) added to the nominal position (Xc), 14. The method according to claim 12 or 13.

15. subsequent corrections are performed at a series of subsequent times during the operational phase of the surgical instrument, the subsequent corrections being additive over time during the operational phase and non-recoverable; 15. The method according to any one of claims 12 to 14.

16. The elasto-plastic correction and the elastic correction are applied simultaneously.

16. The method of claim 14 or 15.

17. The elastic correction and the elasto-plastic correction are applied in different configurations, one of which is enabled or disabled, and the correction contribution of the disabled correction is fixed and maintained, and is subsequently updated when the corresponding correction is enabled.

16. The method of claim 14 or 15.

18. and enabling elastic-plastic compensation control and disabling elastic compensation control of an actuator that closes the articulated end effector when a closing force is recognized during the operation phase.

18. The method of claim 17.

19. The respective nominal strokes (Δ ｘ，ｊ activating electric actuators associated with the tendons in the antagonistic tendon pair according to The step of estimating the desired target force may include calculating the nominal stroke (Δ ｘ，ｊ ) desired target force F(Δ ｘ，ｊ ) detecting the actual force (F) includes determining a target actual force (F) based on an actual force applied by the one or more actuated electric actuators; The at least one length change (Δ ｌ The step of estimating and / or calculating the length change (Δ) due to plastic elongation or elasto-plastic elongation of the tendons included in the antagonistic tendon pair is based on the respective predicted elastic forces and the determined target actual force (F). ｌ，ｊ ), and controlling the position of the at least one electric actuator includes controlling an electric actuator associated with a tendon in an antagonist tendon pair to reach the target actual force (F).

19. The method of any one of claims 11 to 18.

20. determining the target actual force (F) includes determining an arithmetic average of the forces detected at two of the antagonist tendons as the target actual force (F); 20. The method of claim 19.

21. determining the target actual force (F) includes determining a maximum force among the forces detected at two of the antagonist tendons as the target actual force (F); 20. The method of claim 19.

22. The steps of the method are performed iteratively, and the step of determining the target actual force (F) includes determining the target actual force (F) as a time average of actual forces detected at two of the antagonist tendons at at least two previous times.

22. The method of any one of claims 11 to 21.

23. The step of determining the target's actual force F(t-1) at time t-1 is performed according to an equation selected from the following equations: [Equation 4] [Equation 5] [Equation 6] [Equation 7] where y is an index representing the time, and F １ and F ２ , F ３ and F ４ denotes the actual forces detected at the two antagonistic tendon pairs, 22. The method of any one of claims 11 to 21.

24. Based on the stroke and / or position of the electric actuator at the target actual force (F), a corrected kinematic zero position P for gripping and / or cutting control is calculated. ０－ｍｏｄ further comprising defining 24. The method of any one of claims 11 to 23.

25. estimating the elastic modulus of the one or more tendons as a function of time (k(t)); 24. The method of any one of claims 11 to 23.

26. the steps of the method are applied only if the target actual force (F) is within a predefined range of values ​​that are considered acceptable; 24. The method of any one of claims 11 to 23.

27. the step of detecting the force exerted by said electric actuators (11, 12, 13, 14, 15, 16) is performed by a respective force sensor or torque sensor operatively connected to each said electric actuator; 27. The method of any one of claims 1 to 26.

28. The surgical instrument (20) further comprises at least one transmission element (21, 22, 23, 24, 25, 26), wherein at least one of the transmission elements (21, 22, 23, 24, 25, 26) is operably connected to a corresponding at least one of the actuating tendons (31, 32, 33, 34, 35, 36) and is operably connectable to a corresponding electric actuator (11, 12, 13, 14, 15, 16); 28. The method of any one of claims 1 to 27.

29. the length change correction parameter is determined in a controlled and variable manner depending on the pose of the articulated end effector (40) to account for different frictions associated with different poses; 29. The method of any one of claims 1 to 28.

30. The actuating tendon is preferably a polymer tendon formed by braided polymer fibers; 30. The method of any one of claims 1 to 29.

31. 1. A robotic system comprising: a surgical instrument (20) having an articulated end effector (40); Control means (9); at least one actuation tendon (31, 32, 33, 34, 35, 36) configured to actuate the articulated end effector (40); at least one electric actuator (11, 12, 13, 14, 15, 16) operably connectable to each of the at least one actuating tendon (31, 32, 33, 34, 35, 36) and configured to impart a movement to each actuating tendon controlled by the control means (9), the at least one electric actuator (11, 12, 13, 14, 15, 16) determining a respective unambiguous correlation between at least one movement of the one or more electric actuators (11, 12, 13, 14, 15, 16) and at least one movement of the articulated end effector (40); Equipped with The control means (9) of the robot system, during an operating phase of the robot system, when at least one of the electric actuators (11, 12, 13, 14, 15, 16) is in contact with at least one of the actuating tendons (31, 32, 33, 34, 35, 36), respectively, A control means (9) provides at least one of the electric actuators (11, 12, 13, 14, 15, 16) with a respective known stroke and / or known position (Δ ｘ ) and / or at each known stroke and / or known position (Δ ｘ a desired target force (F(Δ)) related to the predicted elastic elongation of at least one of said actuated tendons (31, 32, 33, 34, 35, 36) as a function of ｘ ) and an operation of estimating detecting an actual force (F) exerted by at least one of said at least one electric actuator (11, 12, 13, 14, 15, 16); The detected actual force (F) and the desired target force (F(Δ ｘ )) based on the difference between the length change (Δ ｌ estimating and / or calculating configured to run The control means (9) of the robot system The estimated and / or calculated length change (Δ ｌ ) as a corrective input for controlling at least one of the electric actuators (11, 12, 13, 14, 15, 16). Robot system.

32. The operation of detecting the actual force (F) is performed by detecting the known stroke and / or known position (Δ ｘ Detecting an instantaneous actual force (F(t)) applied by at least one of the electric actuators (11, 12, 13, 14, 15, 16) at a time corresponding to the time when a desired target force is estimated.

32. The robotic system of claim 31.

33. The change in length (Δ ｌ The operation of estimating and / or calculating the length change (Δ) due to plastic or elasto-plastic elongation of the actuated tendon is performed using the following equation: ｌ ), [Equation 8] Here, k ｐｌ is the elastic modulus according to the simplified model representing elongation, and α is a parameter related to the elastic-plastic correction function.

33. The robotic system of claim 32.

34. The operation of detecting the actual force (F) is performed by detecting the known stroke and / or known position (Δ ｘ Detecting an instantaneous actual force (F(t-1)) applied by at least one of the electric actuators (11, 12, 13, 14, 15, 16) at a known time interval prior to the time at which the desired target force is estimated.

32. The robotic system of claim 31.

35. The control of the at least one electric actuator includes position control of the at least one electric actuator (11, 12, 13, 14, 15, 16); The position control is The change in length (Δ) of at least one of the actuated tendons due to plastic elongation or elastic-plastic elongation of the at least one actuated tendon. ｌ ), to impart movement to at least one of the electric actuators (11, 12, 13, 14, 15, 16) to determine the change in length (Δx) between the force F(t) exerted on the articulated end effector and the desired nominal force F(Δx) of the articulated end effector. ｌ ) reducing or cancelling errors caused by 35. The robot system of any one of claims 31 to 34.

36. The position control is The estimated and / or calculated length change (Δ l ) is set to the initial reference kinematic zero position (P ０ ) to obtain the corrected kinematic zero position (P ０－ｍｏｄ ), [Equation 9] 36. The robotic system of claim 35.

37. The operations are performed iteratively in a discrete sequence of operations to estimate, in particular, the length change (Δ ｌ (t)) is calculated based on the actual force F(t-1) detected at the previous time, 37. The robot system of any one of claims 34 to 36.

38. The position of at least one of the electric actuators at time t is calculated by the corrected kinematic zero position (P ０－ｍｏｄ ) or as a function of the initial reference kinematic zero position (P ０ ) and the length change due to plastic or elasto-plastic elongation of the actuated tendon (Δ ｌ (t)) and the instantaneous position (Δ ｘ (t)) according to the following formula: [Equation 10] 38. The robotic system of claim 37.

39. the robotic system is a master-slave system, and the surgical instrument is a slave device controlled by a master device of the robotic system according to a control mode; a control means (9) of the robot system configured to control the system in such a way that, in the absence of external forces, the error between the pose commanded by the master device and the pose reached by the articulated end effector (40) of the slave device is minimized within a finite time; 39. The robotic system of any one of claims 31 to 38.

40. the surgical instrument (20) comprises a plurality of actuating tendons (31, 32, 33, 34, 35, 36), and the robotic system comprises a corresponding plurality of electric actuators (11, 12, 13, 14, 15, 16); The desired target force (F(Δ ｘ ) is performed with reference to several or all of the actuated tendons (31, 32, 33, 34, 35, 36), The operation of detecting the actual force (F) is performed for a plurality or all of the electric actuators (11, 12, 13, 14, 15, 16), The change in length (Δ ｌ ) is performed with reference to several or all of the electric actuators (11, 12, 13, 14, 15, 16), The change in length (Δ ｌ ) as a correction input is performed with reference to several or all of the electric actuators (11, 12, 13, 14, 15, 16), 40. The robotic system of any one of claims 31 to 39.

41. a master device of the robotic system is a handheld, unconstrained master device adapted to be moved by an operator and manipulated by the operator with degrees of freedom associated with opening, closing, and / or cutting the grip of a surgical slave instrument; each of the one or more actuating tendons (31, 32, 33, 34, 35, 36) is operatively connected to both the respective electric actuators and the articulated end effector (40) of the robot system to actuate a respective degree of freedom of the one or more degrees of freedom of the articulated end effector (40); said actuating tendons (31, 32, 33, 34, 35, 36) comprise one or more pairs of antagonistic tendons, configured to control, for example, opening, closing and / or cutting, respectively, the grasping performed by the two tips or tweezers or ends (43, 44) of the articulated end effector (40) of the slave surgical instrument; The change in length (Δ ｌ ) as a corrective input, the operation is performed with reference to the tendons in the antagonistic tendon pair, thereby controlling the gripping opening / closing degree of freedom and / or cutting degree of freedom; 41. The robot system according to claim 39 or 40.

42. the control means (9) of the robotic system are configured to perform the operations according to any one of claims 31 to 41 during the operation phase of the surgical instrument only during the sub-phase of grasping the two tips or tweezers or ends (43, 44), During the operating phase of the surgical instrument, the orientation and opening and closing of the articulated end effector (40) of the surgical instrument are position-controlled; the elastic-plastic correction is activated only during the grasping sub-phase, and the correction contribution of the elastic-plastic correction is added to the position control.

42. The robotic system of claim 41.

43. the control means (9) of the robotic system is further adapted to calculate and perform in real time an elastic correction of the elastic elongation experienced by at least one of the actuated tendons; Either or both of the elasto-plastic correction and the elastic correction are performed and applied, and the position control is performed based on the correction contribution of the elastic correction (Δx ｅ ) and the correction contribution due to elastic-plastic correction (Δx ｅｐ ) together determine the compensated position (X(t)) added to the nominal position (Xc), 43. The robotic system of claim 42.

44. subsequent corrections are performed at a series of subsequent times during the operational phase of the surgical instrument, the subsequent corrections being additive over time during the operational phase and non-recoverable; 44. The robot system of any one of claims 42 to 43.

45. the elasto-plastic correction and the elastic correction are applied simultaneously, and / or The elastic correction and the elasto-plastic correction are applied in different configurations, one of which is enabled or disabled, and the correction contribution of the disabled correction is fixed and maintained, and is subsequently updated when the corresponding correction is enabled.

45. A robotic system according to claim 43 or 44.

46. and enabling elastic-plastic compensation control and disabling elastic compensation control of an actuator that closes the articulated end effector when a closing force is recognized during the operation phase.

46. ​​The robotic system of claim 45.

47. The control means (9) further comprises a nominal stroke (Δ) at which the tip or end of the articulated end effector (40) is expected to contact and lock the gripping and / or cutting degrees of freedom. ｘ，ｊ and actuating electric actuators associated with the tendons in the antagonistic tendon pair according to The operation of estimating the desired target force is to calculate the nominal stroke (Δ ｘ，ｊ ) desired target force F(Δ ｘ，ｊ ) the act of detecting the actual force (F) includes determining a target actual force (F) based on an actual force applied by the one or more actuated electric actuators; The at least one length change (Δ ｌ The operation of estimating and / or calculating the length change (Δ) due to plastic or elasto-plastic elongation of the tendons included in the antagonistic tendon pair is based on the respective predicted elastic forces and the determined target actual force (F). ｌ，ｊ ), and controlling the position of the at least one electric actuator includes controlling an electric actuator associated with a tendon in an antagonist tendon pair to reach the target actual force (F).

47. The robotic system of any one of claims 41 to 46.

48. the act of determining the target actual force (F) includes determining an arithmetic average of the forces detected at two of the antagonist tendons as the target actual force (F); or and determining the target actual force (F) includes determining a maximum force among the forces detected at two of the antagonist tendons as the target actual force (F).

48. The robotic system of claim 47.

49. the control means (9) of the robot system is configured to repeatedly execute the operation, and the operation of determining the target actual force (F) comprises determining as the target actual force (F) a time average of actual forces detected by two of the antagonist tendons at at least two previous times.

49. The robotic system of any one of claims 41 to 48.

50. The operation of determining the actual force F(t-1) of the target at time t-1 is performed according to an equation selected from the following equations: [0011] [0012] [0013] [0014] where y is an index representing the time, and F １ and F ２ , F ３ and F ４ denotes the actual forces detected at the two antagonistic tendon pairs, 49. The robotic system of any one of claims 41 to 48.

51. The control means (9) of the robot system calculates a corrected kinematic zero position P for gripping and / or cutting control based on the stroke and / or position of the electric actuator at the target actual force (F). ０－ｍｏｄ further configured to define 51. The robotic system of any one of claims 41 to 50.

52. the control means (9) of the robotic system is configured to perform a further operation of estimating the elastic modulus of one or more tendons as a function of time (k(t)).

51. The robotic system of any one of claims 41 to 50.

53. the control means (9) of the robot system is configured to execute the action only if the actual force (F) of the target is within a predefined range of values ​​considered acceptable, 51. The robotic system of any one of claims 41 to 50.

54. detecting the force exerted by said electric actuators (11, 12, 13, 14, 15, 16) is performed by a respective force sensor or torque sensor operatively connected to each said electric actuator; 54. The robotic system of any one of claims 41 to 53.

55. The surgical instrument (20) further comprises at least one transmission element (21, 22, 23, 24, 25, 26), wherein at least one of the transmission elements (21, 22, 23, 24, 25, 26) is operably connected to a corresponding at least one of the actuating tendons (31, 32, 33, 34, 35, 36) and is operably connectable to a corresponding electric actuator (11, 12, 13, 14, 15, 16); 55. The robotic system of any one of claims 41 to 54.

56. the length change correction parameter is determined in a controlled and variable manner depending on the pose of the articulated end effector (40) to account for different frictions associated with different poses; 56. The robotic system of any one of claims 41 to 55.

57. The actuating tendon is preferably a polymer tendon formed by braided polymer fibers; 56. The robotic system of any one of claims 41 to 55.

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