Position sensorless control method for robot magnetic reduction gear joint motor

Abstract

The present invention discloses a position sensorless control method for a robot magnetic reduction gear joint motor, and relates to the technical field of electric transmission control equipment. First, the relationship between the electromagnetic torque and the rotation speed in the electromagnetic torque equation and the mechanical motion equation of the robot magnetic reduction gear joint motor in a synchronous rotating coordinate system is established, and a dynamic sliding mode layer is introduced to improve the system response speed on the basis of improving the control effect of the position sensorless control method. According to the influence of the position sensorless controller on the system's chattering phenomenon, the sliding mode gain is designed to achieve dynamic adjustment of the high frequency of the overshoot of the sliding mode control model. Finally, the stability analysis of the system is performed using the Lyapunov stability criterion. Based on the position sensorless controller system under the joint action of the improved sliding mode gain and the dynamic sliding mode layer in the present invention, the anti-interference ability of the robot magnetic reduction gear joint motor system can be improved, the overshoot can be significantly reduced, and the chattering problem can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of electric drive control equipment, in particular to a position sensorless control method for a robot magnetic reduction gear joint motor. Background Art

[0002] In the research of robot joint motor transmission, the controller based on mechanical position sensor will bring problems such as high cost, extra space occupation and low reliability. Therefore, sensorless control has attracted more and more attention. Position information monitoring is an important indicator for performance evaluation, so the design of joint motor sensors is particularly important. Compared with mechanical reduction gears, magnetic reduction gears have the important characteristics of non-contact, frictionless energy consumption and smooth transmission. They are the core components for realizing the electromechanical energy conversion of robot joint motors. They are in an important position of energy conversion and play the role of joint motor shock absorption. They play the role of matching speed and transmitting torque between the prime mover and the working machine or actuator, which is of great significance to ensure the reliable operation of the robot.

[0003] After searching relevant patents and literature at home and abroad, although there are many methods for improving the position information detection of robot joint motors, no patents and literature on the position sensorless control method of robot magnetic reduction gear joint motors were found. The relevant literature on position sensorless control methods of similar motors are as follows, such as "Position Sensorless Control Strategy of Permanent Magnet Synchronous Motor Based on Improved Dual Sliding Mode". A position sensorless control strategy based on an improved dual sliding mode algorithm is designed to address the switching oscillation problem of traditional PI control of the permanent magnet synchronous motor speed loop and the low observation accuracy and severe jitter of the traditional sliding mode observer. However, this method cannot be applied to magnetic reduction gear joint motors because it does not solve the dynamic response and overshoot control strategy of permanent magnet synchronous motors.

[0004] The existing sliding mode control still has problems such as slow response, high overshoot frequency, and jitter in the application of robot magnetic reduction gear joint motor control. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a position sensorless control method for the magnetic reduction gear joint motor of a robot. The present invention can improve the anti-interference ability of the magnetic reduction gear joint motor system of the robot, significantly reduce the overshoot and effectively solve the jitter problem.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] According to a position sensorless control method of a robot magnetic reduction gear joint motor proposed by the present invention,

[0008] The relationship between the electromagnetic torque equation of the robot's magnetic reduction gear joint motor and the electromagnetic torque and speed in the mechanical motion equation is established in a synchronous rotating coordinate system, and a dynamic sliding mode layer is introduced;

[0009] According to the influence of the position sensorless controller on the chattering phenomenon of the position sensorless controller system, the sliding mode gain is designed to realize the dynamic adjustment of the sliding mode control model;

[0010] The stability analysis of the position sensorless controller system is carried out using the Lyapunov stability criterion.

[0011] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, the electromagnetic torque equation of the robot magnetic reduction gear joint motor is as follows:

[0012]

[0013] Among them, T e is the motor electromagnetic torque, P n is the polar logarithm, i d is the d-axis current component, i q is the q-axis current component, R is the resistance, L d is the d-axis inductance component, L q is the q-axis inductance component, Ψ f is the permanent magnet flux.

[0014] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, the mechanical motion equation of the robot magnetic reduction gear joint motor is as follows:

[0015]

[0016] Among them, ω m is the mechanical angular velocity, T L is the load torque, B is the viscous friction coefficient, J is the moment of inertia, and t is time.

[0017] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, the sliding mode control model is specifically as follows:

[0018]

[0019] in, is the expected value of the q-axis current, c and is a parameter, δ is the sliding mode gain, sat(s) is the saturation function for achieving smooth switching, sgn(*) is the sign function, s is the sliding surface function, and Δ is the saturation function boundary layer.

[0020] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, sat(s) is used to replace the saturation function of the traditional sliding mode control to achieve smooth switching.

[0021] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, according to the influence of the position sensorless controller on the chattering phenomenon of the position sensorless controller system, the sliding mode gain is designed to realize the dynamic adjustment of the sliding mode control model; specifically as follows:

[0022] According to the influence of sliding mode gain on system response speed and chattering phenomenon, a dynamic sliding mode layer is designed to realize dynamic adjustment of sliding mode gain. Combining the relationship between electromagnetic torque and speed in the electromagnetic torque equation (1) of the robot magnetic reduction gear joint motor system and the mechanical motion equation (2), the dynamic sliding mode layer parameter λ is defined as follows:

[0023]

[0024] in, is the estimated mechanical angular velocity;

[0025] The desired motor speed is obtained by controlling the electromagnetic torque, thereby improving the expected current value of the sliding mode controller and obtaining the position sensorless controller η combined with the dynamic sliding mode layer:

[0026]

[0027] in, is the deviation between the actual value and the observed value obtained by the q-axis current sampling circuit, and μ is the observed value of the induced electromotive force;

[0028] The dynamic sliding mode controller is combined with the position sensorless controller to improve the output expected value according to the relationship between the electromagnetic torque and the q-axis current;

[0029] Update the sliding mode gain to:

[0030]

[0031] Where K represents the gain coefficient of the sliding mode controller.

[0032] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, the stability analysis of the position sensorless controller system is performed using the Lyapunov stability criterion, as follows:

[0033] Define the Lyapunov function as:

[0034]

[0035] Where V is the Lyapunov function;

[0036] According to Lyapunov stability theory, the terminal sliding surface of the position sensorless controller entering the sliding mode and being stable needs to satisfy:

[0037]

[0038] in, The derivative of the Lyapunov function, is the expected value of η, is the expected value of the q-axis current component, the superscript T indicates the transpose, yes The transposed matrix of , since the performance parameter index matrix A and the terminal sliding surface matrix B are negative definite, the sliding mode gain δ>0 is satisfied, and the position sensorless controller system is asymptotically stable.

[0039] As a further optimization scheme of the position sensorless control method of the robot magnetic reduction gear joint motor described in the present invention, the sliding mode gain is designed to achieve dynamic adjustment of the high frequency of overshoot of the sliding mode control model.

[0040] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0041] (1) Compared with the conventional sliding mode variable structure control system, adding a dynamic sliding mode layer to the position sensorless controller further improves the response speed of the robot magnetic reduction gear joint motor system; when the system calibration position deviation is not zero, the dynamic sliding mode layer and the position sensorless controller work together to improve the system convergence speed. When the system calibration position deviation is zero, the dynamic sliding mode layer works, allowing the position sensorless controller to obtain the expected output value faster.

[0042] (2) Compared with conventional sliding mode variable structure control systems, the method of the present invention combines the improved sliding mode gain with the dynamic sliding mode layer to jointly work on a position sensorless controller system, which can significantly improve the system response speed and greatly reduce the overshoot, effectively improve the position information extraction and control effect of the robot's magnetic reduction gear joint motor, and can effectively enter the sliding mode and reduce the motor system jitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] In view of the problems of slow response and high overshoot frequency in the application of sliding mode control in the control of robot magnetic reduction gear joint motor, the present invention proposes a position sensorless control method of the dynamic sliding mode layer of the robot magnetic reduction gear joint motor. Firstly, the relationship between the electromagnetic torque and the speed in the electromagnetic torque equation and the mechanical motion equation of the robot magnetic reduction gear joint motor in the synchronous rotating coordinate system is established, and the dynamic sliding mode layer is introduced to improve the system response speed on the basis of improving the control effect of the position sensorless control method. According to the influence of the position sensorless controller on the system's jitter phenomenon, the sliding mode gain is designed to realize the dynamic adjustment of the high overshoot frequency of the sliding mode control model. Finally, to ensure the stability of the system, the Lyapunov stability criterion is used to analyze the stability of the system.

[0046] like Figure 1 As shown, the specific steps of the present invention are as follows:

[0047] The electromagnetic torque equation of the robot magnetic reduction gear joint motor is expressed as:

[0048]

[0049] Among them, T e is the motor electromagnetic torque, P n is the polar logarithm, i d is the d-axis current component, i q is the q-axis current component, R is the resistance, L d is the d-axis inductance component, L q is the q-axis inductance component, Ψ f is the permanent magnet flux.

[0050] The mechanical motion equation of the robot magnetic reduction gear joint motor is expressed as:

[0051]

[0052] Among them, ω m is the mechanical angular velocity, T L is the load torque, B is the viscous friction coefficient, J is the moment of inertia, and t is time.

[0053] The sliding mode control model of the position sensorless control method based on the dynamic sliding mode layer is established as shown in formula (3):

[0054]

[0055] in, is the expected value of the q-axis current, c and is the parameter to be designed, δ is the sliding mode gain to be designed, sat(s) is the saturation function for achieving smooth switching, sgn(*) is the sign function, s is the sliding surface function, and Δ is the saturation function boundary layer.

[0056] According to the influence of sliding mode gain on system response speed and chattering phenomenon, a dynamic sliding mode layer is designed to realize dynamic adjustment of sliding mode gain. Combining the relationship between electromagnetic torque and speed in the electromagnetic torque equation (1) of the robot magnetic reduction gear joint motor system and the mechanical motion equation (2), the dynamic sliding mode layer parameter λ is defined as shown in equation (4).

[0057]

[0058] In the formula, is the estimated value of the mechanical angular velocity. By controlling the electromagnetic torque, the desired motor speed is obtained, thereby improving the expected current value of the sliding mode controller and obtaining a position sensorless controller combined with a dynamic sliding mode layer (5).

[0059]

[0060] in, It represents the deviation between the actual value and the observed value obtained by the q-axis current sampling circuit, and μ is the observed value of the induced electromotive force.

[0061] The dynamic sliding mode controller is combined with a position sensorless controller to improve the output expected value according to the relationship between the electromagnetic torque and the q-axis current, thereby increasing the response speed of the system.

[0062] Secondly, in order to enable the position sensorless controller of the dynamic sliding mode layer to reach the sliding mode accurately and quickly, the sliding mode gain to be designed needs to be updated as:

[0063]

[0064] Among them, K represents the gain coefficient of the sliding mode controller. Finally, in order to verify the system stability of the position sensorless controller of the dynamic sliding mode layer, the Lyapunov function is defined as:

[0065]

[0066] Where V is the Lyapunov function.

[0067] According to Lyapunov stability theory, the terminal sliding surface of the position sensorless controller entering the sliding mode and being stable needs to satisfy:

[0068]

[0069] in, The derivative of the Lyapunov function, is the expected value of η, is the expected value of the q-axis current component, the superscript T indicates the transpose, yes The transposed matrix of , since the performance parameter index matrix A and the terminal sliding surface matrix B are negative definite, the sliding mode gain δ>0 is satisfied, and the position sensorless controller system is asymptotically stable.

[0070] Based on the position sensorless controller system under the joint action of the improved sliding mode gain and the dynamic sliding mode layer in the present invention, the anti-interference ability of the robot magnetic reduction gear joint motor system can be improved, the overshoot can be significantly reduced, and the jitter problem can be effectively solved. The difference from the conventional sliding mode variable structure control system lies in the discontinuity of the sliding mode, that is, the "sliding mode" of the switching characteristics of the system structure that changes over time. In the present invention, when the system calibration position deviation is not zero, the dynamic sliding mode layer and the position sensorless controller work together to improve the system convergence speed. When the system calibration position deviation is zero, the dynamic sliding mode layer takes effect, so that the position sensorless controller can obtain the expected output value faster. Table 1 shows the main parameters of the robot magnetic reduction gear joint motor structure.

[0071] Table 1 Main parameters of the robot magnetic reduction gear joint motor

[0072]

[0073] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A position sensorless control method for a robot magnetic reduction gear joint motor, characterized in that: The relationship between the electromagnetic torque equation of the robot's magnetic reduction gear joint motor and the electromagnetic torque and speed in the mechanical motion equation is established in a synchronous rotating coordinate system, and a dynamic sliding mode layer is introduced; According to the influence of the position sensorless controller on the chattering phenomenon of the position sensorless controller system, the sliding mode gain is designed to realize the dynamic adjustment of the sliding mode control model; Stability analysis of position sensorless controller system using Lyapunov stability criterion; The electromagnetic torque equation of the robot magnetic reduction gear joint motor is as follows: Among them, T e is the motor electromagnetic torque, P n is the polar logarithm, i d is the d-axis current component, i q is the q-axis current component, R is the resistance, L d is the d-axis inductance component, L q is the q-axis inductance component, Ψ f is the permanent magnet flux linkage; The mechanical motion equation of the robot magnetic reduction gear joint motor is as follows: Among them, ω m is the mechanical angular velocity, T L is the load torque, B is the viscous friction coefficient, J is the moment of inertia, and t is the time; The specific sliding mode control model is: in, is the expected value of the q-axis current, c and is a parameter, δ is the sliding mode gain, sat(s) is the saturation function for achieving smooth switching, sgn(*) is the sign function, s is the sliding surface function, and Δ is the saturation function boundary layer.

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