A precise tracking control method for the ankle joint of a bionic dummy

Abstract

The present invention discloses a method for accurately tracking and controlling a bionic dummy ankle joint. The bionic dummy ankle joint is provided with a two-link structure, including a calf rod and a sole rod that are hinged to each other. A sole drive motor is provided on the sole rod at the end connected to the calf rod; a calf drive motor is provided on the calf rod away from the end connected to the sole rod; sensors are provided on the calf rod and the sole rod respectively to measure the angular position, angular velocity and angular acceleration of the calf rod and the sole rod; a tracking error is obtained according to the expected angular position and the measured angular position, and the tracking error is made to converge rapidly through a sliding mode control method, so as to realize accurate tracking of the bionic dummy ankle joint to the expected trajectory. The method for accurately tracking and controlling a bionic dummy ankle joint disclosed by the present invention realizes rapid convergence and avoids the problem of non-singularity, and is suitable for control under high-speed sports such as ice and snow sports.

Description

Technical Field

[0001] The invention relates to a precise tracking control method for a bionic dummy ankle joint, belonging to the technical field of simulation control. Background Art

[0002] Ice and snow sports require specific venues and are accompanied by high-speed movements. When building an ice and snow sports venue, the venue needs to be tested. However, real-person testing can easily cause injuries. Using bionic dummies instead of real people is a better method.

[0003] Ice and snow sports require movement learning and guidance. Using bionic dummies for movement guidance is an effective method that can solve the problem of insufficient coaches and provide standard movement demonstrations.

[0004] Traditional dummies are only used for collision tests, and the degree of harm to the human body is inferred from the appearance of damage. Due to the particularity of ice and snow sports, requirements are made for the dummy's ankle joint movement, angle maintenance and high-frequency rotation.

[0005] Therefore, it is necessary to study the control method of the bionic dummy ankle joint so that the bionic dummy ankle joint can accurately track the desired trajectory signal. Summary of the invention

[0006] In order to overcome the above problems, the inventors have conducted in-depth research and proposed a method for accurate tracking and control of a bionic dummy ankle joint. The bionic dummy ankle joint is a two-link structure, including a calf rod and a sole rod that are hinged to each other. A sole drive motor is provided on the sole rod at the end connected to the calf rod, so that the sole rod can rotate relative to the calf rod; a calf drive motor is provided on the calf rod, away from the end connected to the sole rod, so that the angle between the calf rod and the horizontal plane can change;

[0007] A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar;

[0008] The tracking error is obtained according to the expected angular position and the measured angular position, and the tracking error is quickly converged through the sliding mode control method, so that the bionic dummy ankle joint can accurately track the expected trajectory.

[0009] Furthermore, in the sliding mode control method, the error dynamics model is set as:

[0010] e1=qq d

[0011]

[0012]

[0013] Where e1 represents the angular position tracking error vector of the bionic dummy ankle joint, q represents the angular position of the bionic dummy ankle joint obtained by measurement, and q d represents the desired angular position, M0(q) represents the nominal value of the positive definite mass inertia matrix, u represents the control input torque, represents the sum of unknown disturbance and noise, represents the nominal value of the sum of the Coriolis force and gravity,

[0014] The angular position, desired angular position, and control input torque all include the calf and foot, and are expressed as:

[0015] q=[q1,q2] T

[0016] q d =[q d1 ,q d2 ] T

[0017] u=[u1,u2] T

[0018] Among them, the calf angle position q1 is the angle between the extension of the sole rod and the horizontal line, the sole angle position q2 is the angle between the extension of the calf rod and the sole rod, and the desired calf angle position q d1 represents the desired angular position of q1, and the desired angular position of the sole of the foot q d2 represents the desired angular position of q2, u1 represents the control input torque of the calf, and u2 represents the control input torque of the sole of the foot.

[0019] Furthermore, in the sliding mode control method, the sliding surface is set to a fixed-time convergent non-singular terminal sliding surface.

[0020] In a preferred embodiment, the sliding surface s is set to:

[0021]

[0022] Among them, α and β are design parameters.

[0023] In a preferred embodiment, in the sliding mode control method, the reaching law is set as:

[0024]

[0025]

[0026] μ is the design parameter, is an adaptive parameter.

[0027] Further preferably, the control rate of the adaptive parameter is set to:

[0028]

[0029] Among them, α0, α1, and α2 are design parameters.

[0030] Furthermore, in the sliding mode control method, the control law is set as:

[0031]

[0032] Another aspect of the present invention provides a bionic dummy ankle joint, comprising a calf rod, a sole rod and a microprocessor.

[0033] The calf rod and the sole rod are hinged to form a two-link structure. A sole drive motor is provided on the sole rod at the end connected to the calf rod, so that the sole rod can rotate relative to the calf rod; a calf drive motor is provided on the calf rod away from the end connected to the sole rod, so that the angle between the calf rod and the horizontal plane can be changed;

[0034] A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar;

[0035] The microprocessor performs sliding mode control on the calf drive motor and the sole drive motor according to one of the above preferred methods.

[0036] The beneficial effects of the present invention include:

[0037] (1) It not only achieves fast convergence, but also avoids non-singular problems, achieving high-precision and high-continuity control, which is suitable for control of high-speed sports such as ice and snow sports;

[0038] (2) It has fast tracking speed and good effect for large angle changes, and can adapt to the rapid changes in ice and snow sports. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic flow chart of a method for accurate tracking and controlling a bionic dummy ankle joint according to a preferred embodiment of the present invention is shown;

[0040] Figure 2 A schematic diagram of an equivalent two-link structure for a bionic dummy ankle joint precise tracking control method according to a preferred embodiment of the present invention is shown;

[0041] Figure 3 The angle tracking situation in the simulation results of Example 1 is shown;

[0042] Figure 4 The angular velocity variation in the simulation results of Example 1 is shown;

[0043] Figure 5 The angle tracking situation in the simulation results of Example 2 is shown;

[0044] Figure 6 The angular velocity variation in the simulation results of Example 2 is shown. DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present invention will become more clear and distinct.

[0046] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0047] The present invention provides a method for accurately tracking and controlling a bionic dummy ankle joint. The bionic dummy ankle joint is simulated by a two-link structure, comprising a calf rod and a sole rod that are hinged to each other. A sole drive motor is arranged on the sole rod at the end connected to the calf rod, so that the sole rod can rotate relative to the calf rod; a calf drive motor is arranged on the calf rod, away from the end connected to the sole rod, so that the angle between the calf rod and the horizontal plane can be changed.

[0048] A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar;

[0049] The tracking error is obtained according to the expected angular position and the measured angular position, and the tracking error is quickly converged through the sliding mode control method, so that the bionic dummy ankle joint can accurately track the expected trajectory.

[0050] In the present invention, the desired trajectory is converted into a desired angular position, which is then transmitted to the bionic dummy ankle joint, and the desired angular position is tracked by a sliding mode control method, thereby achieving accurate tracking of the bionic dummy ankle joint on the desired trajectory.

[0051] According to the present invention, in the sliding mode control method, the error dynamics model is set as:

[0052] e1=qq d

[0053]

[0054]

[0055] Where e1 represents the angular position tracking error vector of the bionic dummy ankle joint, q represents the angular position of the bionic dummy ankle joint obtained by measurement, and q drepresents the desired angular position, M0(q) represents the nominal value of the positive definite mass inertia matrix, u represents the control input torque, represents the sum of unknown disturbance and noise, represents the nominal value of the sum of the Coriolis force and gravity,

[0056] Since the bionic dummy ankle joint includes a calf rod and a sole rod connected to each other, the angular position, the desired angular position and the control input torque all include the calf and the sole, which can be expressed as:

[0057] q=[q1,q2] T

[0058] q d =[q d1 ,q d2 ] T

[0059] u=[u1,u2] T

[0060] Among them, the calf angle position q1 is the angle between the extension of the sole rod and the horizontal line, and the sole angle position q2 is the angle between the extension of the calf rod and the sole rod, such as Figure 2 As shown, the desired angular position q of the lower leg d1 represents the desired angular position of q1, and the desired angular position of the sole of the foot q d2 represents the desired angular position of q2, u1 represents the control input torque of the calf, and u2 represents the control input torque of the sole of the foot.

[0061] Furthermore, in the sliding mode control method, the sliding surface is set as a fixed time convergent non-singular terminal sliding surface, and the sliding surface s is set as:

[0062]

[0063] Among them, α and β are design parameters.

[0064] Preferably, 1<α<2, β>0.

[0065] The sliding surface is also the result of optimization for high-speed movement under ice and snow conditions. The sliding surface can quickly achieve rapid approach, thereby reducing the delay effect of signal tracking, making the dummy's movement more sensitive, so that continuous large movements such as sharp turns and sudden braking can be performed in a short time.

[0066] According to a preferred embodiment of the present invention, in the sliding mode control method, the reaching law is set as:

[0067]

[0068]

[0069] Among them, μ is the design parameter, is an adaptive parameter.

[0070] Furthermore, the control rate of the adaptive parameter is set as:

[0071]

[0072] Among them, α0, α1, and α2 are design parameters.

[0073] The above-mentioned adaptive parameter settings not only have a better ability to suppress jitter, but also reduce the input control accuracy requirements compared to the traditional ones, thereby improving the fault tolerance rate, improving the robustness of the control system, and solving the problem of increased risk of loss of control caused by high-speed movement of ice and snow.

[0074] Furthermore, in the sliding mode control method, the control law is set as:

[0075]

[0076] On the other hand, the present invention also provides a bionic dummy ankle joint, comprising a calf rod, a sole rod and a microprocessor.

[0077] The calf rod and the sole rod are hinged to form a two-link structure. A sole drive motor is provided on the sole rod at the end connected to the calf rod, so that the sole rod can rotate relative to the calf rod; a calf drive motor is provided on the calf rod away from the end connected to the sole rod, so that the angle between the calf rod and the horizontal plane can be changed;

[0078] A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar;

[0079] The microprocessor performs sliding mode control on the calf drive motor and the sole drive motor according to the above method.

[0080] Example

[0081] Example 1

[0082] Set the calf bar and foot bar to change according to the following desired position angles:

[0083]

[0084] A simulation experiment is carried out to obtain the tracking error based on the expected angular position and the measured angular position. The tracking error is quickly converged by the sliding mode control method. In the sliding mode control method,

[0085] Set the sliding surface s to:

[0086]

[0087] Among them, the values ​​of α and β are 5 and 5 respectively.

[0088] The reaching law is set as:

[0089]

[0090]

[0091] The control rate of the adaptive parameters is set as:

[0092]

[0093] Among them, the value of μ is 50, and the values ​​of α0, α1, and α2 are 200, 200, and 200 respectively.

[0094] The value of μ is 50, and the values ​​of α0, α1, and α2 are 200, 200, and 200 respectively.

[0095] The control law is set as:

[0096]

[0097] The simulation results are as follows Figure 3-4 As shown, Figure 3 Shows the angle tracking situation, Figure 4 Shows the change in angular velocity.

[0098] from Figure 3 It can be seen that within a short delay time, the legs can quickly track the expected signal. Due to the selection of step signals, a jump phenomenon will occur when the signal amplitude switches. Figure 4 It can be seen that the bionic dummy ankle joint can respond quickly and further track the expected signal, and the angular velocity of the bionic dummy ankle joint changes smoothly, which is beneficial to ensure the performance and service life of the bionic dummy ankle joint angle.

[0099] Example 2

[0100] The same simulation experiment as in Example 1 was performed, except that the calf bar and the sole bar were set to change according to the following desired position angles:

[0101]

[0102] The expected signal is a composite switching of a step signal and a sine signal. The expected angular position has a higher frequency of change and can simulate the rapid movement of ice and snow. The simulation results are as follows: Figure 5-6 As shown, Figure 5 Shows the angle tracking situation, Figure 6 Shows the change in angular velocity.

[0103] As can be seen from the figure, the displacement of the ankle joint will have a small overshoot and lag, but it will catch up with the expected signal within 1 second, indicating that it has a better tracking effect on complex signals.

[0104] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", etc. indicate positions or positional relationships based on the working state of the present invention, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0105] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0106] The present invention has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, the present invention may be subjected to a variety of substitutions and improvements, all of which fall within the scope of protection of the present invention.

Claims

1. A method for accurate tracking and control of a bionic dummy ankle joint, characterized in that: The bionic dummy ankle joint is simulated by a two-link structure, including a calf rod and a sole rod that are hinged to each other. A sole drive motor is arranged on the sole rod at the end connected with the calf rod, so that the sole rod can rotate relative to the calf rod; and a calf drive motor is arranged on the calf rod away from the end connected with the sole rod, so that the angle between the calf rod and the horizontal plane can be changed. A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar; The tracking error is obtained according to the expected angular position and the measured angular position, and the tracking error is quickly converged through the sliding mode control method, so that the bionic dummy ankle joint can accurately track the expected trajectory. In the sliding mode control method, the error dynamics model is set as: e1=qq d Where e1 represents the angular position tracking error vector of the bionic dummy ankle joint, q represents the angular position of the bionic dummy ankle joint obtained by measurement, and q d represents the desired angular position, M0(q) represents the nominal value of the positive definite mass inertia matrix, u represents the control input torque, represents the sum of unknown disturbance and noise, represents the nominal value of the sum of the Coriolis force and gravity, The angular position, desired angular position, and control input torque all include the calf and foot, and are expressed as: q=[q1,q2] T q d =[q d1 ,q d2 ] T u=[u1,u2] T Among them, the calf angle position q1 is the angle between the extension of the sole rod and the horizontal line, the sole angle position q2 is the angle between the extension of the calf rod and the sole rod, and the desired calf angle position q d1 represents the desired angular position of q1, and the desired angular position of the sole of the foot q d2 represents the desired angular position of q2, u1 represents the control input torque of the calf, and u2 represents the control input torque of the sole; In the sliding mode control method, the sliding surface s is set as: Among them, α and β are design parameters; In the sliding mode control method, the reaching law is set as: μ is the design parameter, is the adaptive parameter; The control rate of the adaptive parameters is set as: Among them, α0, α1, and α2 are design parameters.

2. The method for accurate tracking and control of the bionic dummy ankle joint according to claim 1, characterized in that: In the sliding mode control method, the control law is set as:

3. A bionic dummy ankle joint, characterized in that: Includes calf bar, foot bar and microprocessor, The calf rod and the sole rod are hinged to form a two-link structure. A sole drive motor is provided on the sole rod at the end connected to the calf rod, so that the sole rod can rotate relative to the calf rod; a calf drive motor is provided on the calf rod away from the end connected to the sole rod, so that the angle between the calf rod and the horizontal plane can be changed; A sensor is provided on the shank bar to measure the angular position, angular velocity and angular acceleration of the shank bar, and a sensor is provided on the sole bar to measure the angular position, angular velocity and angular acceleration of the sole bar; The microprocessor performs sliding mode control on the calf drive motor and the sole drive motor according to the method of claim 1 or 2.

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