Robotic ultrasonic scalpel clamping force adaptive control system method

Abstract

A kind of robot ultrasonic scalpel clamping force self-adapting control system and method, the control system includes initialization setting module, current acquisition module, standard current judging module, limit angle judging module and control module.Initialization setting module is used to initially set the clamping force conversion coefficient of the robot ultrasonic scalpel, maximum clamping force, maximum current value and the limit angle when ultrasonic scalpel is used.When the instant current value is less than the maximum current value, the control module drives the motor to work.When the instant current value is greater than or equal to the maximum current value, the control module drives the motor to stop working.When the limit angle judging module obtains completion cutting work, the control module drives the motor to stop working.The present control system can guarantee cutting off entire muscle tissue, and also can guarantee that blood vessels in muscle tissue are all sintered closed by ultrasonic wave.

Description

Technical Field

[0001] This invention relates to the field of surgical instrument technology, and in particular to an adaptive control method for the clamping force of a robotic ultrasonic scalpel. Background Technology

[0002] An ultrasonic scalpel (or ultrasonic blade) uses an ultrasonic frequency generator to drive the handle and blade to vibrate at an ultrasonic frequency (55.5kHz) to perform surgical cutting. During cutting, it breaks the hydrogen bonds in the proteins within the contacted tissue cells, coagulates ruptured blood vessels to stop bleeding, and simultaneously achieves cutting and closure, thus offering high reliability and surgical safety. Currently, ultrasonic surgical systems are the most advanced basic auxiliary instruments for minimally invasive surgery worldwide, and are essential medical equipment in large and medium-sized hospitals globally and in China, widely used in general surgery, obstetrics and gynecology, urology, and other surgeries. When ultrasound waves propagate through a certain medium, they produce mechanical, thermal, and acoustic responses. Ultrasonic surgical systems utilize these characteristics to exert mechanical, thermal, and cavitation effects on tissues, performing related tissue cutting and closure, thereby achieving clinical applications.

[0003] Current ultrasonic scalpels all involve the doctor manually pulling a trigger to close the jaws. The clamping force between the jaws and the guide rod is dynamically adjusted by the doctor's trigger pull. Simultaneously, a spring inside the handle limits the maximum clamping force, ensuring that the clamping force at the tip does not exceed a certain limit. Therefore, the doctor can manually and adaptively adjust the clamping force to meet the different tissue and application conditions required in clinical practice.

[0004] However, with the development of automated control, the surgical control of ultrasonic scalpels is also performed by robots. After the ultrasonic scalpel is connected to the robot, the clamping and other actions of the ultrasonic scalpel are indirectly controlled by the robotic arm of the surgical robot's patient operating table after receiving instructions from the doctor's worktable, and then linked through communication. Therefore, the entire feedback loop of the clamping force is interrupted, meaning that the doctor cannot accurately perceive the clamping force at the end of the instrument.

[0005] Currently, existing methods for controlling the gripping force of robots are based on fixed motor rotation angles, without any force-related control. Therefore, in cases with significant differences in tissue volume, such as thin or thick muscles, the gripping force at the distal end will vary greatly, requiring surgeons to visually identify tissue changes. This is particularly problematic in delicate surgical procedures, hindering the effective clinical application of ultrasonic scalpels.

[0006] Therefore, there is a disadvantage to using a robot to control an ultrasonic scalpel. The surgeon can no longer directly sense the force exerted by the surgical robot's end effector, and the clamping force of the ultrasonic scalpel is a crucial control parameter in clinical surgical applications. Insufficient clamping force prolongs the surgical time, hindering rapid operation. Excessive clamping force causes muscle tissue to rupture not through ultrasonic cutting, but rather by the ultrasonic scalpel's jaws clamping the muscle tissue instead of ultrasonically cutting it, rendering the ultrasonic scalpel ineffective. This is because when the ultrasonic scalpel cuts, it simultaneously acts as a hemostatic agent, closing blood vessels and achieving hemostasis. Summary of the Invention

[0007] In view of this, the present invention provides an adaptive control system and control method for clamping force of a robotic ultrasonic scalpel that can solve the above-mentioned technical problems.

[0008] An adaptive clamping force control system for a robotic ultrasonic scalpel, the robotic ultrasonic scalpel being driven by a motor. The adaptive clamping force control system includes an initialization setting module, a current acquisition module, a standard current judgment module, a limit angle judgment module, and a control module. The initialization setting module is used to initially set the clamping force conversion coefficient, maximum clamping force, maximum current value, and limit angle of the ultrasonic scalpel during use. The clamping force conversion coefficient is used to calculate the correspondence between the torque output by the motor and the clamping force of the ultrasonic scalpel. The motor drives the robotic ultrasonic scalpel to output clamping force. The maximum current value is used to limit the maximum current that can be loaded, and this maximum current value is calculated from the maximum clamping force. The limit angle is used to limit whether the ultrasonic scalpel completes a surgical cut. The current acquisition module is used to acquire the value of the current loaded by the motor in real time. The standard current judgment module is used to determine whether the acquired real-time current value is less than the maximum current value. When the real-time current value is less than the maximum current value, the control module drives the motor to operate. When the instantaneous current value is greater than or equal to the maximum current value, the control module drives the motor to stop working. The limit angle judgment module is used to determine whether the robotic ultrasonic scalpel has completed the cutting operation. When the limit angle judgment module determines that the cutting operation has been completed, the control module drives the motor to stop working.

[0009] Furthermore, the clamping force conversion coefficient is determined by the ultrasonic scalpel used.

[0010] Furthermore, the clamping force conversion system is determined by a finite number of tests.

[0011] Furthermore, the robotic ultrasonic surgical tool has a shank and a jaw, and the force generated when the jaw and the shank are closed is the clamping force.

[0012] Furthermore, the limiting angle is determined by the rotation angle of the motor.

[0013] Furthermore, the maximum clamping force is determined based on clinical experience.

[0014] Furthermore, the maximum current value is calculated from the maximum clamping force, as specifically disclosed below:

[0015] Fj=Kc*Tm=Kc*Kt*Ia

[0016] Where Fj is the clamping force, Kc is the clamping force conversion coefficient; Tm is the torque, Kt is the torque constant, and Ia is the motor current.

[0017] Furthermore, the motor is equipped with at least two sensors to detect the instantaneous current value and rotation angle, respectively.

[0018] An adaptive control method for the clamping force of a robotic ultrasonic surgical scalpel includes the following steps:

[0019] STEP101: Provides a robotic ultrasonic scalpel and a clamping force adaptive control system for controlling the operation of the robotic ultrasonic scalpel. The robotic ultrasonic scalpel includes a motor, and the clamping force adaptive control system includes an initialization setting module, a current acquisition module, a standard current judgment module, an extreme angle judgment module, and a control module.

[0020] STEP102: The initialization setting module sets the clamping force conversion coefficient, maximum clamping force, maximum current value, and the limit angle when using the ultrasonic scalpel.

[0021] STEP103: Return the robotic ultrasonic scalpel to its zero position;

[0022] STEP104: Start the robot's ultrasonic scalpel to begin working. The motor starts to rotate and output torque. At the same time, the current acquisition module collects the real-time current value loaded by the motor.

[0023] STEP105: The standard current judgment module determines whether the instantaneous current value is greater than the maximum current value;

[0024] STEP106: When the instantaneous current value is greater than or equal to the maximum current value, the control module drives the motor to stop working until the detected instantaneous current value is less than the maximum current value, and then restarts the motor to continue working.

[0025] STEP107: When the instantaneous current value is less than the maximum current value, the limit angle judgment module determines whether the angle rotated by the motor is equal to the limit angle. If the angle rotated by the motor is equal to the limit angle, the operation stops. If the angle rotated by the motor is less than the limit angle, the control module continues to drive the motor to work.

[0026] Furthermore, the motor is equipped with at least two sensors to detect the instantaneous current value and rotation angle, respectively.

[0027] Compared to existing technologies, the adaptive clamping force control system of the robotic ultrasonic scalpel provided by this invention, through the coordinated operation of multiple functional modules such as an initialization setting module, a current acquisition module, a standard current judgment module, a limit angle judgment module, and a control module, enables an ultrasonic cut to be completed once the motor reaches its set limit angle of rotation. During this process, the motor moves intermittently, ensuring that while cutting through the entire muscle tissue, all blood vessels within the muscle tissue are also sintered and closed by the ultrasound. No additional monitoring instruments are required during the cutting process, thereby improving the success rate of the surgery and reducing the occurrence of medical accidents. Attached Figure Description

[0028] Figure 1 This invention provides a schematic diagram of the clamping force adaptive control system for a robotic ultrasonic scalpel.

[0029] Figure 2 The flowchart illustrates an adaptive control method for clamping force of a robotic ultrasonic scalpel, as provided by this invention. Detailed Implementation

[0030] The following provides a more detailed description of specific embodiments of the present invention. It should be understood that the description of the embodiments of the present invention herein is not intended to limit the scope of protection of the present invention.

[0031] like Figure 1The diagram shown is a principle block diagram of a clamping force adaptive control system for a robotic ultrasonic scalpel provided by the present invention. The clamping force adaptive control system for the robotic ultrasonic scalpel is used to control a robotic ultrasonic scalpel 100 to automatically adapt its clamping force to the needs of the surgeon during operation. The robotic ultrasonic scalpel clamping force adaptive control system includes an initialization setting module 10, a current acquisition module 20, a standard current judgment module 30, a limit angle judgment module 40, and a control module 50. It is conceivable that the robotic ultrasonic scalpel clamping force adaptive control method also includes other functional modules, such as electrical connection components, input / output devices, etc., which are technologies known to those skilled in the art and will not be described in detail here.

[0032] The robotic ultrasonic scalpel 100, controlled by the adaptive clamping force control system, is driven by a motor 101. The structure and working principle of the robotic ultrasonic scalpel itself are existing technology and will not be described further here. The robotic ultrasonic scalpel 100 includes a scalpel bar 102 and a jaw 103. The jaw 103 can rotate under external force, thereby opening and clamping relative to the scalpel bar 102.

[0033] The initialization setting module 10 is used to initially set the clamping force conversion coefficient, maximum clamping force, maximum current value, and limit angle of the ultrasonic scalpel during use. The clamping force conversion coefficient is determined by the characteristics of the ultrasonic scalpel itself; it is a coefficient between the torque or speed output by the motor and the clamping force. It is generally believed that there is a direct proportional relationship between torque and clamping force, i.e., the greater the torque, the greater the clamping force. Therefore, this clamping force conversion coefficient can be determined through multiple or a limited number of experiments. Consequently, the clamping force conversion coefficient of any ultrasonic scalpel is determined before it leaves the factory.

[0034] The maximum clamping force can be determined based on the surgeon's experience in routine surgeries. Of course, it's conceivable that this maximum clamping force isn't based on the conclusions of a single doctor or even a single hospital, but rather on data accumulated from numerous surgeries performed by hospitals nationwide and even globally. Therefore, the maximum clamping force used in a particular surgery is already determined; it simply needs to be selected.

[0035] The maximum current value is used to limit the maximum current that the motor can load, and this maximum current value is calculated from the maximum clamping force, the theoretical derivation of which is as follows.

[0036] Currently, the robotic arms and instruments of surgical robots generally use DC motors for propulsion. When a power supply voltage is applied to the DC motor, the current drives the motor to rotate. The power supply voltage, rotational speed, and torque are all interrelated. The equivalent circuit and formulas for a DC motor are explained below.

[0037] (1) DC relationship expression for a closed circuit: DC relationship expression for a closed circuit

[0038] Ea=R×Ia+Ec

[0039] Where Ea is the power supply voltage, R is the armature resistance, Ia is the motor current, and Ec is the motor induced voltage.

[0040] (2) Equivalent circuit of DC motor: Motor induced voltage:

[0041] Ec = Ke × N

[0042] Where Ec is the induced voltage of the motor, Ke is the back electromotive force coefficient, and N is the motor speed.

[0043] (3) Motor torque:

[0044] T = Kt × Ia

[0045] Where T is the torque, Kt is the torque constant, and Ia is the motor current.

[0046] From the above formula, it can be deduced that the motor torque T is the value obtained by multiplying the torque constant Kt by the motor current Ia. Therefore, the motor torque is directly proportional to the current.

[0047] Therefore, according to the torque-current (TI) characteristic, when torque is applied, the motor current increases by a constant value, that is, it is directly proportional to the applied torque. The motor current is at its maximum at maximum torque, which is when the speed is zero. Therefore, when driving a motor, the driving conditions should be considered based on this relationship.

[0048] Force Transformation Hypothesis

[0049] The DC motor, through gears and other mechanisms within the ultrasonic scalpel's instrument housing, ultimately transmits torque to the scalpel's handle and jaws, converting it into a clamping force between them. This force conversion can be theoretically achieved using basic mechanics principles, or its proportional relationship can be directly established through a finite number of tests. Assuming the clamping force is Fj, the motor output torque is Tm, and the clamping force conversion coefficient is Kc, the following theoretical or experimental conversion relationship can be obtained.

[0050] Fj=Kc*Tm

[0051] Relationship between clamping force and current:

[0052] Based on the torque formula above, the relationship between clamping force and motor current can be obtained.

[0053] Fj=Kc*Tm=Kc*Kt*Ia

[0054] Where Fj is the clamping force, Kc is the clamping force conversion coefficient; Tm is the torque, Kt is the torque constant, and Ia is the motor current.

[0055] As for the torque constant, it is one of the three important constants of a DC motor. The three important constants of a DC motor are: torque constant KT, back electromotive force constant KE, and speed constant Kn.

[0056] The aforementioned constants represent the fundamental characteristics of DC motors and the resulting mechanical properties. Analyzing and studying these important constants of DC motors is crucial for motor engineers in motor design. The torque constant KT of a DC motor is analyzed below.

[0057] In the electromagnetic torque T′=NΦI / a2π, if a=1, the torque constant can be derived:

[0058] KT=T′ / I=NΦ / 2π.

[0059] From the above, we can see the relationship between clamping force and motor drive current. Therefore, current Ia is an important control and detection parameter in the surgical robot control system. Thus, in the control of ultrasonic scalpel clamping force, clamping force and current should be coordinated and controlled so that the magnitude of clamping force can be controlled by controlling the current.

[0060] Using the formula above, once the maximum clamping force is determined, the maximum current value can be calculated.

[0061] The limiting angle refers to the maximum angle of rotation of the motor. When the ultrasonic scalpel is inserted into the patient's body, the doctor cannot see it. With manual operation, the doctor can determine whether the cutting is complete by the reaction force between the scalpel handle and the jaws. However, with a robotic ultrasonic scalpel, the doctor neither sees nor feels it. Therefore, this limiting angle is determined by the angle the motor travels. The angle traveled by the motor can be detected by sensors.

[0062] The current acquisition module 20 is used to acquire the magnitude of the current applied to the motor, i.e., the instantaneous current value. The current sensor used to acquire the magnitude of the current applied to the motor is existing technology and will not be described in detail here.

[0063] The standard current judgment module 30 is used to compare the acquired instantaneous current value with the set maximum current value. When the instantaneous current value is greater than or equal to the maximum current value, it indicates that the ultrasonic scalpel has applied the maximum clamping force. At this time, the control module 50 should drive the motor to stop outputting torque; otherwise, the ultrasonic scalpel will clamp the muscle tissue instead of ultrasonically cutting it. It is understood that when the instantaneous current value is less than the maximum current value, the control module 50 drives the motor to work. Of course, it is conceivable that the control module 50 controls the motor's operating state by cutting off or applying power.

[0064] The limit angle judgment module 40 is used to determine the magnitude of the angle rotated by the motor, that is, to determine whether the robotic ultrasonic scalpel has completed the cutting operation. When the detected angle of motor rotation is less than the limit angle, the control module 50 drives the motor to continue working. When the detected angle of motor rotation is greater than or equal to the limit angle, the control module 50 drives the motor to stop working. Of course, it is conceivable that the sensor for detecting the angle of motor rotation can be a photoelectric encoder, a magnetoelectric encoder, etc., which will not be elaborated here.

[0065] The control module 50 is used to control the output of the motor based on the signals output by the standard current judgment module 30 and the limit angle judgment module 40. Of course, it is conceivable that the control module 50 can be executed by a program, and its program can be written in existing programming languages. Therefore, those skilled in the art should understand that anyone who knows and understands the working principle and concept of this invention can write such a program.

[0066] like Figure 2 As shown, the present invention also provides a clamping force adaptive control method, which includes the following steps:

[0067] STEP101: Provide a robotic ultrasonic scalpel and a clamping force adaptive control system for controlling the operation of the robotic ultrasonic scalpel. The clamping force adaptive control system includes an initialization setting module 10, a current acquisition module 20, a standard current judgment module 30, an extreme angle judgment module 40, and a control module 50.

[0068] STEP102: The initialization setting module 10 sets the clamping force conversion coefficient, maximum clamping force, maximum current value, and the limit angle when using the ultrasonic scalpel.

[0069] STEP103: Return the robotic ultrasonic scalpel to its zero position;

[0070] STEP 104: Start the robot's ultrasonic scalpel to begin working. The motor starts to rotate and output torque. At the same time, the current acquisition module 20 collects the real-time current value loaded by the motor.

[0071] STEP105: The standard current judgment module 30 determines whether the instantaneous current value is greater than the maximum current value;

[0072] STEP106: When the instantaneous current value is greater than or equal to the maximum current value, the control module 50 drives the motor to stop working until the detected instantaneous current value is less than the maximum current value, and then restarts the motor to continue working.

[0073] STEP107: When the instantaneous current value is less than the maximum current value, the limit angle judgment module 40 determines whether the angle rotated by the motor is equal to the limit angle. If the angle rotated by the motor is equal to the limit angle, the operation stops. If the angle rotated by the motor is less than the limit angle, the control module 50 continues to drive the motor to work.

[0074] Compared with existing technologies, the adaptive clamping force control system of the robotic ultrasonic scalpel provided by this invention, through the cooperation of multiple functional modules such as the initialization setting module 10, the current acquisition module 20, the standard current judgment module 30, the limit angle judgment module 40, and the control module 50, enables an ultrasonic cut to be completed once the motor reaches its set limit angle of rotation. During this process, the motor moves intermittently, ensuring that while cutting through the entire muscle tissue, it also ensures that the blood vessels within the muscle tissue are sintered and closed by ultrasound. No additional instruments are needed for monitoring during the cutting process, thereby improving the success rate of the surgery and reducing the occurrence of medical accidents.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions or improvements within the spirit of the present invention are covered within the scope of the claims of the present invention.

Claims

1. An adaptive clamping force control system for a robotic ultrasonic scalpel, wherein the robotic ultrasonic scalpel is driven by a motor, characterized in that: The adaptive clamping force control system of the robotic ultrasonic scalpel includes an initialization setting module, a current acquisition module, a standard current judgment module, a limit angle judgment module, and a control module. The initialization setting module is used to initially set the clamping force conversion coefficient, maximum clamping force, maximum current value, and limit angle of the robotic ultrasonic scalpel during use. The clamping force conversion coefficient is used to calculate the correspondence between the torque output by a motor and the clamping force of the robotic ultrasonic scalpel. The motor is used to drive the robotic ultrasonic scalpel to output clamping force. The maximum current value is used to limit the maximum current that can be loaded, and this maximum current value is calculated from the maximum clamping force. The limit angle is used to limit whether the robotic ultrasonic scalpel completes a surgical cut. The current acquisition module is used to acquire the current value loaded by the motor in real time. The standard current judgment module is used to determine whether the acquired real-time current value is within the acceptable range. When the instantaneous current value is less than the maximum current value, the control module drives the motor to work. When the instantaneous current value is greater than or equal to the maximum current value, the control module drives the motor to stop working until the detected instantaneous current value is less than the maximum current value, then restarts the motor to continue working. The limit angle judgment module is used to determine whether the robotic ultrasonic scalpel has completed the cutting work. When the limit angle judgment module determines that the cutting work has been completed, the control module drives the motor to stop working. When the instantaneous current value is less than the maximum current value, the limit angle judgment module determines whether the angle rotated by the motor is equal to the limit angle. When the angle rotated by the motor is equal to the limit angle, it stops working. When the angle rotated by the motor is less than the limit angle, the control module continues to drive the motor to work. The maximum clamping force is obtained based on clinical experience, and the maximum current value is calculated from the maximum clamping force. The specific formula is as follows: Fj=Kc*Tm=Kc*Kt*Ia Where Fj is the clamping force, Kc is the clamping force conversion coefficient; Tm is the torque, Kt is the torque constant, and Ia is the motor current.

2. The adaptive clamping force control system for the robotic ultrasonic scalpel as described in claim 1, characterized in that: The clamping force conversion coefficient is determined by the ultrasonic scalpel used in the robot.

3. The adaptive clamping force control system for the robotic ultrasonic scalpel as described in claim 2, characterized in that: The clamping force conversion coefficient was determined by a finite number of tests.

4. The adaptive clamping force control system for the robotic ultrasonic scalpel as described in claim 1, characterized in that: The robotic ultrasonic surgical tool has a shank and a jaw; the force generated when the jaw and shank are closed is the clamping force.

5. The adaptive clamping force control system for the robotic ultrasonic scalpel as described in claim 1, characterized in that: The limiting angle is determined by the rotation angle of the motor.

6. The adaptive clamping force control system for the robotic ultrasonic scalpel as described in claim 1, characterized in that: The motor is equipped with at least two sensors to detect the instantaneous current value and rotation angle, respectively.

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