Three closed loop control system and dynamic hysteresis compensation method of EHA drive system

Abstract

The application discloses an EHA driving system three-closed-loop control system and a dynamic hysteresis compensation method, and solves the technical problems of large hydraulic hysteresis error, poor dynamic response and insufficient environmental adaptability of the existing electro-hydraulic actuator. The method comprises a three-level control structure of a position control loop, a speed control loop and a current control loop, the position control loop introduces a load disturbance feedforward compensation based on a state observer, the speed control loop adopts an adaptive sliding mode control strategy, the current control loop executes a decoupling vector control algorithm, and a dynamic hysteresis compensation model based on historical input and disturbance estimation is established in the controller. The system integrates a servo motor, a gear pump, a hydraulic cylinder and a sensor module into an integrated driving control structure, and has the effects of improving control precision, reducing response time delay and correcting hydraulic hysteresis error.

Description

Technical Field

[0001] This invention relates to the field of EHA drive control system technology, specifically to a three-closed-loop control system for EHA drive control system and a dynamic hysteresis compensation method. Background Technology

[0002] An electro-hydraulic actuator (EHA) is a servo system that directly controls the movement of an actuator by driving a hydraulic pump with an electric motor. It is widely used in aerospace, industrial robotics, and high-performance equipment. In this type of system, the electric motor, hydraulic pump, valves, and actuators form a closed-loop drive, and position, speed, or force is adjusted and controlled by an electronic controller. Compared to traditional centralized hydraulic systems, EHA systems are decentralized, have fast response times, and high integration, making them particularly suitable for scenarios requiring high reliability and dynamic response.

[0003] Existing EHA control systems mostly employ an electro-hydraulic conversion structure based on a permanent magnet synchronous motor, combined with typical control strategies such as position control, speed control, and current control to form a feedback loop. Meanwhile, to improve control accuracy, some schemes introduce feedforward compensation or nonlinear modeling methods, such as the Preisach model hysteresis compensation method. However, in practical engineering applications, several key problems still exist: First, the hydraulic cylinder system exhibits significant dynamic hysteresis, easily leading to the accumulation of tracking errors due to factors such as valve core friction and hydraulic compressibility; second, the stability of the control system decreases when there are sudden load changes or parameter disturbances; third, EHA control components generally adopt a discrete configuration, resulting in a large system size and complex structural connections, making it difficult to adapt to miniaturized and highly integrated application scenarios.

[0004] Therefore, how to provide a three-closed-loop control system and dynamic hysteresis compensation method for the EHA drive control system is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] One objective of this invention is to propose a three-closed-loop control system for EHA drive control system and a dynamic hysteresis compensation method, which aims to solve the problems of large hydraulic hysteresis error, unstable dynamic response and low system integration in existing electro-hydraulic actuator control systems.

[0006] The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to an embodiment of the present invention includes the following steps:

[0007] S1. The host computer outputs the target position command and obtains the current position of the hydraulic cylinder piston rod through the linear displacement sensor installed at the end of the hydraulic cylinder piston rod. The displacement error between the target position command and the current position is calculated and used as the input signal of the position control loop in the electro-hydraulic actuator control system.

[0008] S2. The controller of the electro-hydraulic actuator control system processes the displacement error based on the proportional-integral-derivative control law, and generates a speed reference signal by combining the load disturbance feedforward compensation model. The load disturbance feedforward compensation model uses a state observer to estimate the external disturbance load torque and superimposes it into the control signal.

[0009] S3. Input the speed reference signal into the speed control loop, construct the sliding surface function using an adaptive sliding mode control method, and generate a current command based on the speed error. The speed control loop includes a disturbance estimator and a boundary layer switching function module.

[0010] S4. Input the current command into the current control loop, and calculate the d-axis voltage command and q-axis voltage command respectively based on the dq-axis electrical model of the permanent magnet synchronous servo motor through the decoupling vector control method, and compensate for the motor back electromotive force and electrical coupling terms.

[0011] S5. The d-axis voltage command and q-axis voltage command are converted into three-phase PWM control signals by the power drive module to drive the permanent magnet synchronous servo motor to rotate, thereby driving the gear pump to output hydraulic oil and push the hydraulic cylinder piston rod.

[0012] S6. Based on the historical control signals and estimated load disturbance data within the current control cycle, a dynamic hysteresis compensation module is established to correct the nonlinear hysteresis error caused by the compressibility of the hydraulic oil inside the hydraulic cylinder and the friction of the valve core. The dynamic hysteresis compensation module is periodically updated inside the controller and superimposed on the control channel.

[0013] S7. During the operation of the electro-hydraulic actuator drive control system, the servo motor current signal, DC bus voltage signal, servo motor speed signal and hydraulic cylinder piston rod displacement signal are collected in real time. If any signal exceeds the preset safety threshold, the internal fault handling module of the controller is triggered to shut down the power output path and send the fault code to the host computer through the communication interface.

[0014] Optionally, S1 specifically includes:

[0015] S11. The host computer sends a target position command to the electro-hydraulic actuator controller through the communication interface. The target position command is a value in millimeters.

[0016] S12. A linear displacement sensor is installed at the end of the hydraulic cylinder piston rod to measure the current position of the hydraulic cylinder piston rod and output a displacement signal in millimeters.

[0017] S13, The electro-hydraulic actuator controller calculates the displacement error signal based on the target position command and the current position;

[0018] S14. The electro-hydraulic actuator controller updates the target position command, current position and displacement error signal at a fixed sampling period, and inputs the displacement error signal to the position control loop.

[0019] Optionally, S2 specifically includes:

[0020] S21. The electro-hydraulic actuator controller inputs the displacement error signal to the position control loop and executes the proportional-integral-derivative control law composed of the superposition of the proportional, integral and derivative terms to obtain the preliminary speed reference signal.

[0021] S22, The electro-hydraulic actuator controller estimates the disturbance load torque τ of the hydraulic cylinder based on a state observation model. f The state observation model is as follows:

[0022]

[0023] Where, τ f K represents the disturbance load torque. t J represents the motor torque constant. eq B represents the equivalent moment of inertia of the system. eq ω represents the equivalent damping coefficient. m Indicates the servo motor speed. Indicates the acceleration of the servo motor;

[0024] S23, the electro-hydraulic actuator controller will control the disturbance load torque τ f The corrected speed reference signal is superimposed on the initial speed reference signal output by the proportional-integral-derivative control law.

[0025] S24. The electro-hydraulic actuator controller inputs the corrected speed reference signal into the speed control loop in the electro-hydraulic actuator control system, and uses it as the input signal for the sliding mode control algorithm in the speed control loop to participate in the next step of current command generation calculation.

[0026] Optionally, S3 specifically includes:

[0027] S31, The electro-hydraulic actuator controller compares the speed reference signal with the current speed of the servo motor to obtain the speed error signal e. v ;

[0028] S32. The electro-hydraulic actuator controller constructs a sliding surface function s based on the speed error signal. The expression of the sliding surface function is:

[0029]

[0030] Where s is the sliding surface function, e v For speed error, β is the first derivative of the velocity error, and β is the convergence rate coefficient of the sliding surface.

[0031] S33. The electro-hydraulic actuator controller sets the switching function and constructs the control law. The control law includes a proportional-integral term, a sliding mode term, and a disturbance estimation term. The sliding mode control current command u sm( The calculation formula is:

[0032]

[0033] Among them, K vo Proportional gain, K vi λ is the integral gain, and λ is the sliding mode gain. Let be the boundary layer thickness, and let sat(·) be the saturation function. For the disturbance term estimated online;

[0034] S34, the electro-hydraulic actuator controller inputs the sliding mode control current command output by the control law to the current control loop.

[0035] Optionally, S4 specifically includes:

[0036] S41, the electro-hydraulic actuator controller decomposes the current command output from the speed control loop into the d-axis current command i. d and q-axis current command i q And calculate the target drive voltage command v d With v q ;

[0037] S42. The electro-hydraulic actuator controller calculates the drive voltages for the d-axis and q-axis based on the electrical model of the permanent magnet synchronous servo motor. The control formula is as follows:

[0038]

[0039] Among them, v d ,v q For the d-axis and q-axis drive voltage commands, i d i q R represents the actual current along the d-axis and q-axis. s L is the stator resistance. d ,L q Let ω be the inductance along the d-axis and q-axis. e Let ψ be the electric angular velocity of the motor. f For permanent magnet flux linkage;

[0040] S43, Calculation of cross-coupling term -ω for electro-hydraulic actuator controller e ·L q ·i q with +ω e ·(L d ·id +ψ f It also performs decoupling compensation operations between voltage channels;

[0041] S44, the electro-hydraulic actuator controller sends the target drive voltage command v d With v q The input is sent to the power drive module, and the output is a three-phase PWM control signal to the permanent magnet synchronous servo motor.

[0042] Optionally, S6 specifically includes:

[0043] S61. The electro-hydraulic actuator controller records the control input signal u(t-Δt) and the current position θ(t-Δt) of the hydraulic cylinder piston rod in the previous cycle within the control cycle, and combines it with the load disturbance estimate τ collected in the current cycle. f (t), forming a dynamic hysteresis compensation input vector;

[0044] S62. The electro-hydraulic actuator controller constructs a dynamic hysteresis compensation model based on the input vector and performs error estimation in the following form:

[0045] Δθ hyst (t)=α1·u(t-Δt)+α2·τ f (t)+α3·θ(t-Δt);

[0046] Where, Δθ hyst (t) is the estimated hysteresis error, u(t-Δt) is the control input signal, and τ f (t) represents the disturbance load torque, θ(t-Δt) represents the piston rod displacement in the previous cycle, and α1, α2, α3 are the hysteresis modeling coefficients;

[0047] S63, The electro-hydraulic actuator controller converts the estimated hysteresis error value Δθ hyst (t) is subtracted from the position control path to form the corrected position feedback signal:

[0048] θ (orr (t)=θ(t)-Δθ hyst (t);

[0049] Where, θ corr (t) represents the corrected position input signal;

[0050] S64, the electro-hydraulic actuator controller inputs the corrected position signal θ corr (t) Replace the original feedback position signal input to the position control loop to complete the online dynamic compensation for the hydraulic hysteresis effect.

[0051] Optionally, S7 specifically includes:

[0052] S71, the electro-hydraulic actuator controller collects the current signal of the servo motor, the DC bus voltage signal, the servo motor speed signal, and the displacement signal of the hydraulic cylinder piston rod in each control cycle.

[0053] S72. The electro-hydraulic actuator controller compares the four types of signals with their preset safety thresholds respectively. If any signal is detected to exceed the corresponding threshold, it is determined to be an abnormal state.

[0054] S73. When the electro-hydraulic actuator controller responds to an abnormal state, it immediately shuts down the PWM output signal of the power drive module, blocking the drive channel to the servo motor.

[0055] S74, the electro-hydraulic actuator controller sends a fault code to the host computer via the CAN FD communication interface, and simultaneously drives the fault status indicator to light up and the running status indicator to turn off, thus completing the fault indication action.

[0056] Optional, the EHA drive control system is a three-closed-loop control system, including the following modules:

[0057] Electro-hydraulic actuator controller module: used to execute a three-closed-loop control strategy based on position control loop, speed control loop and current control loop;

[0058] Host computer module: connected to the electro-hydraulic actuator controller, sending target position command signals;

[0059] Linear displacement sensor module: installed at the end of the hydraulic cylinder piston rod, it collects the current position of the hydraulic cylinder piston rod and outputs the current position signal to the electro-hydraulic actuator controller;

[0060] Servo motor encoder module: Installed at the end of the permanent magnet synchronous servo motor shaft, it collects the motor's speed and position signals and outputs them to the electro-hydraulic actuator controller;

[0061] Three-phase permanent magnet synchronous servo motor module: Receives the PWM control signal output from the electro-hydraulic actuator controller and drives the connected gear pump to rotate;

[0062] Gear pump module: Driven by the servo motor, it rotates and outputs hydraulic oil;

[0063] Hydraulic system component module: includes a hydraulically controlled check valve, a relief valve and a hydraulic cylinder. Hydraulic oil is input to the hydraulic cylinder after being controlled by the hydraulic system component, causing the piston rod to produce linear displacement.

[0064] Power drive module: Equipped with a SiC MOSFET three-phase full-bridge structure, it receives the d-axis and q-axis voltage command signals output from the electro-hydraulic actuator controller, generates three-phase PWM control signals, and outputs them to the servo motor;

[0065] Current detection module: Configured at the input terminal of the electro-hydraulic actuator controller, it collects the bus current signal of the servo motor;

[0066] DC bus voltage detection module: Collects the DC bus voltage value of the system and feeds it back to the electro-hydraulic actuator controller;

[0067] The beneficial effects of this invention are:

[0068] (1) By constructing a three-closed-loop control structure consisting of a position control loop, a speed control loop and a current control loop, and combining a state observer and a sliding mode control algorithm, the controller maintains strong control stability and response consistency under conditions such as load disturbance, friction change and parameter offset.

[0069] (2) By adopting a dynamic hysteresis compensation model based on historical control input, external disturbance estimation and previous cycle position state, the hysteresis error caused by oil compressibility and valve core friction in the hydraulic system can be estimated and corrected in real time, thereby improving the positioning accuracy of the hydraulic cylinder piston rod.

[0070] (3) The system structure adopts an integrated approach of servo motor, hydraulic pump, controller and sensor module, which simplifies wiring and reduces system size, and is conducive to the construction of a miniaturized and highly integrated drive and control platform. Attached Figure Description

[0071] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0072] Figure 1 This is a structural block diagram of the three-closed-loop control system of the EHA drive and control system proposed in this invention;

[0073] Figure 2 This is the internal three-loop control structure diagram of the EHA drive control system three-loop control system and dynamic hysteresis compensation method proposed in this invention.

[0074] Figure 3 This is a logic block diagram of the dynamic hysteresis compensation path of the three-closed-loop control system and dynamic hysteresis compensation method of the EHA drive control system proposed in this invention. Detailed Implementation

[0075] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0076] refer to Figure 1-3The EHA drive control system's three-closed-loop control system and dynamic hysteresis compensation method include the following steps:

[0077] S1. The host computer outputs the target position command and obtains the current position of the hydraulic cylinder piston rod through the linear displacement sensor installed at the end of the hydraulic cylinder piston rod. The displacement error between the target position command and the current position is calculated and used as the input signal of the position control loop in the electro-hydraulic actuator control system.

[0078] S2. The controller of the electro-hydraulic actuator control system processes the displacement error based on the proportional-integral-derivative control law, and generates a speed reference signal by combining the load disturbance feedforward compensation model. The load disturbance feedforward compensation model uses a state observer to estimate the external disturbance load torque and superimposes it into the control signal.

[0079] S3. Input the speed reference signal into the speed control loop, construct the sliding surface function using an adaptive sliding mode control method, and generate a current command based on the speed error. The speed control loop includes a disturbance estimator and a boundary layer switching function module.

[0080] S4. Input the current command into the current control loop, and calculate the d-axis voltage command and q-axis voltage command respectively based on the dq-axis electrical model of the permanent magnet synchronous servo motor through the decoupling vector control method, and compensate for the motor back electromotive force and electrical coupling terms.

[0081] S5. The d-axis voltage command and q-axis voltage command are converted into three-phase PWM control signals by the power drive module to drive the permanent magnet synchronous servo motor to rotate, thereby driving the gear pump to output hydraulic oil and push the hydraulic cylinder piston rod.

[0082] S6. Based on the historical control signals and estimated load disturbance data within the current control cycle, a dynamic hysteresis compensation module is established to correct the nonlinear hysteresis error caused by the compressibility of the hydraulic oil inside the hydraulic cylinder and the friction of the valve core. The dynamic hysteresis compensation module is periodically updated inside the controller and superimposed on the control channel.

[0083] S7. During the operation of the electro-hydraulic actuator drive control system, the servo motor current signal, DC bus voltage signal, servo motor speed signal and hydraulic cylinder piston rod displacement signal are collected in real time. If any signal exceeds the preset safety threshold, the internal fault handling module of the controller is triggered to shut down the power output path and send the fault code to the host computer through the communication interface.

[0084] In this embodiment, S1 specifically includes:

[0085] S11. The host computer sends a target position command to the electro-hydraulic actuator controller through the communication interface. The target position command is a value in millimeters.

[0086] S12. A linear displacement sensor is installed at the end of the hydraulic cylinder piston rod to measure the current position of the hydraulic cylinder piston rod and output a displacement signal in millimeters.

[0087] S13, The electro-hydraulic actuator controller calculates the displacement error signal based on the target position command and the current position;

[0088] S14. The electro-hydraulic actuator controller updates the target position command, current position and displacement error signal at a fixed sampling period, and inputs the displacement error signal to the position control loop.

[0089] This implementation method constructs an error calculation path between the target position command and the actual displacement of the hydraulic cylinder piston rod, thereby enabling real-time acquisition of position deviation and establishing a complete input signal path for the position control loop, providing a stable data foundation for subsequent control loops and compensation modules.

[0090] In this embodiment, S2 specifically includes:

[0091] S21. The electro-hydraulic actuator controller inputs the displacement error signal to the position control loop and executes the proportional-integral-derivative control law composed of the superposition of the proportional, integral and derivative terms to obtain the preliminary speed reference signal.

[0092] S22, The electro-hydraulic actuator controller estimates the disturbance load torque τ of the hydraulic cylinder based on a state observation model. f The state observation model is as follows:

[0093]

[0094] Where, τ f K represents the disturbance load torque. t J represents the motor torque constant. eq B represents the equivalent moment of inertia of the system. eq ω represents the equivalent damping coefficient. m Indicates the servo motor speed. Indicates the acceleration of the servo motor;

[0095] S23, the electro-hydraulic actuator controller will control the disturbance load torque τ f The corrected speed reference signal is superimposed on the initial speed reference signal output by the proportional-integral-derivative control law.

[0096] S24. The electro-hydraulic actuator controller inputs the corrected speed reference signal into the speed control loop in the electro-hydraulic actuator control system, and uses it as the input signal for the sliding mode control algorithm in the speed control loop to participate in the next step of current command generation calculation.

[0097] This implementation introduces a load disturbance feedforward compensation module based on a state observer into the position control loop, enabling the speed reference signal to incorporate load dynamic prediction information while including position deviation information. This constructs a speed command generation path that combines feedback and prediction, enhancing the system's continuous control capability under external disturbance conditions.

[0098] In this embodiment, S3 specifically includes:

[0099] S31, The electro-hydraulic actuator controller compares the speed reference signal with the current speed of the servo motor to obtain the speed error signal e. v ;

[0100] S32. The electro-hydraulic actuator controller constructs a sliding surface function s based on the speed error signal. The expression of the sliding surface function is:

[0101]

[0102] Where s is the sliding surface function, e v For speed error, β is the first derivative of the velocity error, and β is the convergence rate coefficient of the sliding surface.

[0103] S33. The electro-hydraulic actuator controller sets the switching function and constructs the control law. The control law includes a proportional-integral term, a sliding mode term, and a disturbance estimation term. The sliding mode control current command u smc The calculation formula is:

[0104]

[0105] Among them, K vp Proportional gain, K vi λ is the integral gain, and λ is the sliding mode gain. Let be the boundary layer thickness, and let sat(·) be the saturation function. For the disturbance term estimated online;

[0106] S34, the electro-hydraulic actuator controller inputs the sliding mode control current command output by the control law to the current control loop.

[0107] This implementation method embeds an adaptive sliding mode control method into the speed control loop, constructs a sliding mode surface function and a disturbance estimation channel, realizes convergent adjustment of the dynamic characteristics of speed error and real-time estimation of uncertain external disturbances, provides robust current command input to the current control loop, and improves the system's adaptability to sudden loads or friction fluctuations.

[0108] In this embodiment, S4 specifically includes:

[0109] S41, the electro-hydraulic actuator controller decomposes the current command output from the speed control loop into the d-axis current command i. d and q-axis current command i q And calculate the target drive voltage command v d With v q ;

[0110] S42. The electro-hydraulic actuator controller calculates the drive voltages for the d-axis and q-axis based on the electrical model of the permanent magnet synchronous servo motor. The control formula is as follows:

[0111]

[0112] Among them, v d ,v q For the d-axis and q-axis drive voltage commands, i d i q R represents the actual current along the d-axis and q-axis. s L is the stator resistance. d ,L q Let ω be the inductance along the d-axis and q-axis. e Let ψ be the electric angular velocity of the motor. f For permanent magnet flux linkage;

[0113] S43, Calculation of cross-coupling term -ω for electro-hydraulic actuator controller e ·L q ·i q with +ω e ·(L d ·i d +ψ f It also performs decoupling compensation operations between voltage channels;

[0114] S44, the electro-hydraulic actuator controller sends the target drive voltage command v d With v q The input is sent to the power drive module, and the output is a three-phase PWM control signal to the permanent magnet synchronous servo motor.

[0115] This implementation method uses a vector decoupling control method based on the motor electrical model to compensate for voltage crosstalk between the d-axis and q-axis and the influence of the permanent magnet back electromotive force, making the motor drive current channel response more independent. This helps maintain the high dynamic characteristics of the motor and provides continuous and stable flow drive capability for the downstream hydraulic actuators.

[0116] In this embodiment, S6 specifically includes:

[0117] S61. The electro-hydraulic actuator controller records the control input signal u(t-Δt) and the current position θ(t-Δt) of the hydraulic cylinder piston rod in the previous cycle within the control cycle, and combines it with the load disturbance estimate τ collected in the current cycle.f (t), forming a dynamic hysteresis compensation input vector;

[0118] S62. The electro-hydraulic actuator controller constructs a dynamic hysteresis compensation model based on the input vector and performs error estimation in the following form:

[0119] Δθ hyst (t)=α1·u(t-Δt)+α2·τ f (t)+α3·θ(t-Δt);

[0120] Where, Δθ hyst (t) is the estimated hysteresis error, u(t-Δt) is the control input signal, and τ f (t) represents the disturbance load torque, θ(t-Δt) represents the piston rod displacement in the previous cycle, and α1, α2, α3 are the hysteresis modeling coefficients;

[0121] S63, The electro-hydraulic actuator controller converts the estimated hysteresis error value Δθ hyst (t) is subtracted from the position control path to form the corrected position feedback signal:

[0122] θ corr (t)=θ(t)-Δθ hyst (t);

[0123] Where, θ corr (t) represents the corrected position input signal;

[0124] S64, the electro-hydraulic actuator controller inputs the corrected position signal θ corr (t) Replace the original feedback position signal input to the position control loop to complete the online dynamic compensation for the hydraulic hysteresis effect.

[0125] This implementation method establishes a dynamic hysteresis compensation model based on control input, disturbance estimation, and historical displacement within the controller. This model corrects the position lag error caused by the nonlinearity of the hydraulic system in real time, making the position feedback path closer to the actual physical response and improving the tracking consistency and control accuracy of the system under high-frequency dynamic conditions.

[0126] In this embodiment, S7 specifically includes:

[0127] S71, the electro-hydraulic actuator controller collects the current signal of the servo motor, the DC bus voltage signal, the servo motor speed signal, and the displacement signal of the hydraulic cylinder piston rod in each control cycle.

[0128] S72. The electro-hydraulic actuator controller compares the four types of signals with their preset safety thresholds respectively. If any signal is detected to exceed the corresponding threshold, it is determined to be an abnormal state.

[0129] S73. When the electro-hydraulic actuator controller responds to an abnormal state, it immediately shuts down the PWM output signal of the power drive module, blocking the drive channel to the servo motor.

[0130] S74, the electro-hydraulic actuator controller sends a fault code to the host computer via the CAN FD communication interface, and simultaneously drives the fault status indicator to light up and the running status indicator to turn off, thus completing the fault indication action.

[0131] This implementation method achieves real-time monitoring and fault handling of the operating status of the electro-hydraulic actuator drive control system by periodically detecting and judging current, voltage, speed and displacement signals, combined with communication feedback and fault indication mechanisms. This ensures that the system can promptly stop control output in abnormal situations, preventing equipment damage and uncontrolled operation.

[0132] In this embodiment, the EHA drive control system's three-closed-loop control system includes the following modules:

[0133] Electro-hydraulic actuator controller module: used to execute a three-closed-loop control strategy based on position control loop, speed control loop and current control loop;

[0134] Host computer module: connected to the electro-hydraulic actuator controller, sending target position command signals;

[0135] Linear displacement sensor module: installed at the end of the hydraulic cylinder piston rod, it collects the current position of the hydraulic cylinder piston rod and outputs the current position signal to the electro-hydraulic actuator controller;

[0136] Servo motor encoder module: Installed at the end of the permanent magnet synchronous servo motor shaft, it collects the motor's speed and position signals and outputs them to the electro-hydraulic actuator controller;

[0137] Three-phase permanent magnet synchronous servo motor module: Receives the PWM control signal output from the electro-hydraulic actuator controller and drives the connected gear pump to rotate;

[0138] Gear pump module: Driven by the servo motor, it rotates and outputs hydraulic oil;

[0139] Hydraulic system component module: includes a hydraulically controlled check valve, a relief valve and a hydraulic cylinder. Hydraulic oil is input to the hydraulic cylinder after being controlled by the hydraulic system component, causing the piston rod to produce linear displacement.

[0140] Power drive module: Equipped with a SiC MOSFET three-phase full-bridge structure, it receives the d-axis and q-axis voltage command signals output from the electro-hydraulic actuator controller, generates three-phase PWM control signals, and outputs them to the servo motor;

[0141] Current detection module: configured at the input terminal of the electro-hydraulic actuator controller to collect the bus current signal of the servo motor;

[0142] DC bus voltage detection module: Collects the DC bus voltage value of the system and feeds it back to the electro-hydraulic actuator controller;

[0143] This implementation establishes an SVPWM modulation mechanism and a digitally isolated drive path, realizing the mapping of d-axis and q-axis voltage commands to three-phase PWM power waveforms, ensuring the controllability of the entire drive signal chain from coordinate transformation and sector determination to switching time generation. Digital isolation logic and dead-time control prevent bridge arm shoot-through, improving the operational safety of the drive circuit. The power drive module achieves high-speed switching capability through SiC devices, reducing switching losses while maintaining current modulation accuracy. Combined with dynamic bus voltage limiting, it maintains a stable linear control range for the motor voltage output, thus completing a full power closed-loop path from control command output to motor electromagnetic energy injection, forming a dynamic response mechanism with multi-stage linkage.

[0144] Example 1:

[0145] To verify the feasibility of this invention in practice, it was applied to the overall debugging of a tracked high-mobility engineering robot platform. Traditional electro-hydraulic actuation systems suffer from problems such as slow response, poor control accuracy, and insufficient disturbance rejection. Especially in scenarios with non-steady load changes or significant hydraulic hysteresis effects, the system is prone to error amplification and positional drift, seriously affecting the safety and user experience of platform operation. This platform needs to perform high-frequency reciprocating motion at a frequency of 1Hz within an actuation range of ±25mm, and the control error must not exceed ±0.1mm. In traditional position-velocity dual-loop control, the lack of current-level adjustment capability, coupled with the inherent hysteresis of the hydraulic system, leads to slow closed-loop response, poor system stability, and nonlinear anomalies such as crawling and rebound during the actuation process. To solve the above problems, this embodiment applies an EHA drive control system three-closed-loop control system and a dynamic hysteresis compensation method. The system highly integrates the controller, motor drive, power bridge, current sampling, and sensor interface into one unit, featuring high integration, sensitive control, remote upgradeability, and strong adaptability to extreme working conditions. The software structure adopts a dual-program approach, consisting of a Boot Loader and an App, and enables remote maintenance through an upgradeable architecture. The control algorithm employs a nested three-loop structure of position, velocity, and current, combined with hysteresis modeling and real-time compensation mechanisms, which significantly improves the control accuracy and dynamic stability of the actuation system.

[0146] After the platform powers on, the controller first starts the Boot Loader program and listens for a remote upgrade command within 2 seconds. If an upgrade flag is received, the system reads the current software version, receives the new firmware compressed package from the host computer, performs data integrity verification, and writes it to the FLASH memory. After writing is complete, the FLASH data is read back for verification. Once the writing is confirmed to be correct, the system jumps to the APP program to run. If no upgrade request is received, the system automatically enters the APP control program and loads the control algorithm logic.

[0147] The APP program first completes system initialization, including configuring the ADC, PWM, DIDO, and CAN communication modules, clock calibration, hardware interrupt enabling, and loading control parameters from the EEPROM. After initialization, the system enters the soft-start control process. First, the soft-start relay K1 is closed while the input relay K2 remains open. The bus voltage begins to rise slowly, and the system samples the voltage every 0.2 seconds using the ADC. When the voltage exceeds 80% of the bus reference value, the system closes K2 and opens K1, entering normal power supply mode. The entire soft-start process lasts 3.4 seconds, with the current rise rate controlled within 1.3 A / s and the maximum inrush current not exceeding 4.6 A.

[0148] The system then enters a three-loop control phase. The outer loop is the position loop, which receives displacement feedback from the position sensor, compares it with commands, and outputs drive signals. The middle loop receives commands from the previous stage, adjusts the error between the target speed and the actual speed, and has strong anti-interference capabilities. The inner loop is the current loop, which samples the current in real time and adjusts the voltage output to achieve rapid control of the servo motor. The motor controls the three-phase power bridge output through an SVPWM modulator, drives the gear pump, and ultimately controls the hydraulic cylinder. This control structure achieves fine-tuning in three dimensions: position, speed, and current, ensuring stable system operation under complex loads and rapid response requirements.

[0149] The system interrupt service routine executes every 0.5ms, including sampling and over-limit judgment of current, voltage, speed, and position. If the sampled value exceeds the system's set threshold (e.g., current > 48A, voltage > 65V, temperature > 70℃, displacement deviation > ±3mm), the system immediately turns off the running indicator light, illuminates the fault light, sends a fault frame to the host computer, and disables PWM output to ensure the system is in a protected state. If the parameters are normal, the PWM duty cycle is updated according to the latest output instruction, and closed-loop operation continues. The main loop program executes non-real-time tasks such as communication processing, LED control, parameter reporting, and key input recognition at 10ms cycles to ensure communication stability and human-machine interaction responsiveness.

[0150] This system employs a hysteresis estimation and correction algorithm based on the Preisach model. By storing the control direction, response deviation, and output error of the previous cycle, it dynamically matches the hysteresis curve segment and introduces a feedforward correction in the control command of the next cycle, thereby achieving early cancellation of the hysteresis effect. During dynamic response, the system maintains good following performance within the range of sudden load changes, direction reversals, or small valve openings, avoiding the jumps, overshoots, and steady-state oscillations that occur in traditional systems.

[0151] The platform vehicle operates within a ±20mm actuation range using a 1Hz square wave displacement command. After 10,000 cycles, the system's operating status and test results are as follows:

[0152] Table 1. Performance Comparison Data of EHA Systems

[0153]

[0154] In multiple real-world control scenarios, the system demonstrated good stability and robustness. In particular, during periods of frequent reverse motion, different load switching, or drastic changes in hydraulic hysteresis, the control error converged significantly, and common problems of traditional systems such as crawling, jumping, and control oscillations did not occur.

[0155] In the low-temperature extreme condition test (-30℃), the system ran continuously for 12 hours under high-frequency operation. The surface temperature of the controller housing did not exceed 45℃, the thermal junction temperature of the internal power devices was within the safe range, and no fault protection mechanisms such as overvoltage, overcurrent, or overtemperature were triggered. The system remained stable.

[0156] The system's remote upgrade function was also verified in testing. Under network disconnection and reconnection conditions, a complete software update process was completed via the Boot Loader mechanism, taking a total of 13.5 seconds with 100% data integrity. The system automatically jumped to the new version of the app to continue running, demonstrating that the software architecture possesses strong fault tolerance and engineering practicality.

[0157] The data and actual operational performance in the above summary show that the three-closed-loop control structure and dynamic hysteresis compensation mechanism in the integrated EHA drive and control system can systematically solve the problems of slow response, large error, strong hysteresis and high energy consumption of traditional hydraulic actuators. It has extremely high technical adaptability, stability and control accuracy under extreme combat conditions, meets the multiple key indicator requirements of high-performance unmanned platforms for the actuation system, and has broad engineering promotion value.

[0158] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A dynamic hysteresis compensation method for three-closed-loop control of EHA drive control system, characterized in that, Includes the following steps: S1. The host computer outputs the target position command and obtains the current position of the hydraulic cylinder piston rod through the linear displacement sensor installed at the end of the hydraulic cylinder piston rod. The displacement error between the target position command and the current position is calculated and used as the input signal of the position control loop in the electro-hydraulic actuator control system. S2. The controller of the electro-hydraulic actuator control system processes the displacement error based on the proportional-integral-derivative control law, and generates a speed reference signal by combining the load disturbance feedforward compensation model. The load disturbance feedforward compensation model uses a state observer to estimate the external disturbance load torque and superimposes it into the control signal. S3. Input the speed reference signal into the speed control loop, construct the sliding surface function using an adaptive sliding mode control method, and generate a current command based on the speed error. The speed control loop includes a disturbance estimator and a boundary layer switching function module. S4. Input the current command into the current control loop, based on the permanent magnet synchronous servo motor. The shaft electrical model is calculated separately using the decoupled vector control method. Shaft voltage command and Shaft voltage command, and compensation for motor back EMF and electrical coupling terms; S5, the above Shaft voltage command and The shaft voltage command is converted into a three-phase PWM control signal by the power drive module to drive the permanent magnet synchronous servo motor to rotate, which in turn drives the gear pump to output hydraulic oil and pushes the piston rod of the hydraulic cylinder. S6. Based on the historical control signals and estimated load disturbance data within the current control cycle, a dynamic hysteresis compensation module is established to correct the nonlinear hysteresis error caused by the compressibility of the hydraulic oil inside the hydraulic cylinder and the friction of the valve core. The dynamic hysteresis compensation module is periodically updated inside the controller and superimposed on the control channel. S7. During the operation of the electro-hydraulic actuator drive control system, the servo motor current signal, DC bus voltage signal, servo motor speed signal and hydraulic cylinder piston rod displacement signal are collected in real time. If any signal exceeds the preset safety threshold, the internal fault handling module of the controller is triggered to shut down the power output path and send the fault code to the host computer through the communication interface. S6 specifically includes: S61, The electro-hydraulic actuator controller records the control input signal of the previous cycle within the control cycle. Hydraulic cylinder piston rod position compared to the previous control cycle And combined with the load disturbance estimate collected in the current period This forms a dynamic hysteresis compensation input vector; S62. The electro-hydraulic actuator controller constructs a dynamic hysteresis compensation model based on the input vector and performs error estimation in the following form: ； in, This is the estimated value of the hysteresis error. To control the input signal, To disturb the load torque, This refers to the position of the hydraulic cylinder piston rod in the previous control cycle. , , Modeling coefficients for hysteresis; S63, the electro-hydraulic actuator controller will use the estimated hysteresis error value Subtracting from the position control path yields the corrected position feedback signal: ； in, This indicates the corrected position input signal; S64, the electro-hydraulic actuator controller inputs the corrected position signal. The original feedback position signal is replaced by the position control loop to complete the online dynamic compensation for the hydraulic hysteresis effect.

2. The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to claim 1, characterized in that, S1 specifically includes: S11. The host computer sends a target position command to the electro-hydraulic actuator controller through the communication interface. The target position command is a value in millimeters. S12. A linear displacement sensor is installed at the end of the hydraulic cylinder piston rod to measure the current position of the hydraulic cylinder piston rod and output a displacement signal in millimeters. S13, The electro-hydraulic actuator controller calculates the displacement error signal based on the target position command and the current position; S14. The electro-hydraulic actuator controller updates the target position command, current position and displacement error signal at a fixed sampling period, and inputs the displacement error signal to the position control loop.

3. The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to claim 1, characterized in that, S2 specifically includes: S21. The electro-hydraulic actuator controller inputs the displacement error signal to the position control loop and executes the proportional-integral-derivative control law composed of the superposition of the proportional, integral and derivative terms to obtain the preliminary speed reference signal. S22, The electro-hydraulic actuator controller estimates the disturbance load torque on the hydraulic cylinder based on a state observation model. The state observation model is as follows: ； in, This indicates the disturbance load torque. Represents the motor torque constant. This represents the equivalent moment of inertia of the system. This represents the equivalent damping coefficient. Indicates the servo motor speed. Indicates the acceleration of the servo motor; S23, the electro-hydraulic actuator controller will control the disturbance load torque The corrected speed reference signal is superimposed on the initial speed reference signal output by the proportional-integral-derivative control law. S24. The electro-hydraulic actuator controller inputs the corrected speed reference signal into the speed control loop in the electro-hydraulic actuator control system, and uses it as the input signal for the sliding mode control algorithm in the speed control loop to participate in the next step of current command generation calculation.

4. The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to claim 1, characterized in that, S3 specifically includes: S31, the electro-hydraulic actuator controller compares the speed reference signal with the current speed of the servo motor to obtain the speed error signal. ; S32. The electro-hydraulic actuator controller constructs a sliding surface function s based on the speed error signal. The expression of the sliding surface function is: ； in, For sliding surface functions, For speed error, The first derivative of the velocity error. The convergence rate coefficient of the sliding surface; S33. The electro-hydraulic actuator controller sets the switching function and constructs the control law. The control law includes a proportional-integral term, a sliding mode term, and a disturbance estimation term. The sliding mode control current command is also included. The calculation formula is: ； in, Proportional gain, For integral gain, For sliding mode gain, For boundary layer thickness, It is a saturation function. For the disturbance term estimated online; S34, the electro-hydraulic actuator controller inputs the sliding mode control current command output by the control law to the current control loop.

5. The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to claim 1, characterized in that, S4 specifically includes: S41, the electro-hydraulic actuator controller decomposes the current command output from the speed control loop into... Shaft current command and Shaft current command And calculate the target drive voltage command. and ; S42. The electro-hydraulic actuator controller calculates based on the electrical model of the permanent magnet synchronous servo motor. shaft and The drive voltage of the shaft is controlled by the following formula: ； ； in, , for shaft and Shaft drive voltage command, , for shaft and Actual shaft current, For stator resistance, , for shaft and Shaft inductor, The electric angular velocity of the motor. For permanent magnet flux linkage; S43, Calculation of cross-coupling terms for electro-hydraulic actuator controller and And perform decoupling compensation operations between voltage channels; S44, the electro-hydraulic actuator controller sends the target drive voltage command. and The input is sent to the power drive module, and the output is a three-phase PWM control signal to the permanent magnet synchronous servo motor.

6. The dynamic hysteresis compensation method for three-closed-loop control of the EHA drive control system according to claim 1, characterized in that, Specifically, S7 includes: S71, the electro-hydraulic actuator controller collects the current signal of the servo motor, the DC bus voltage signal, the servo motor speed signal, and the displacement signal of the hydraulic cylinder piston rod in each control cycle. S72. The electro-hydraulic actuator controller compares the four types of signals with their preset safety thresholds respectively. If any signal is detected to exceed the corresponding threshold, it is determined to be an abnormal state. S73. When the electro-hydraulic actuator controller responds to an abnormal state, it immediately shuts down the PWM output signal of the power drive module, blocking the drive channel to the servo motor. S74, the electro-hydraulic actuator controller sends a fault code to the host computer via the CAN FD communication interface, and simultaneously drives the fault status indicator to light up and the running status indicator to turn off, thus completing the fault indication action.

7. A three-loop control system for EHA drive control system, applied to the dynamic hysteresis compensation method for three-loop control of EHA drive control system as described in any one of claims 1-6, characterized in that, Includes the following modules: Electro-hydraulic actuator controller module: used to execute a three-closed-loop control strategy based on position control loop, speed control loop and current control loop; Host computer module: connected to the electro-hydraulic actuator controller, sending target position command signals; Linear displacement sensor module: installed at the end of the hydraulic cylinder piston rod, it collects the current position of the hydraulic cylinder piston rod and outputs the current position signal to the electro-hydraulic actuator controller; Servo motor encoder module: Installed at the end of the permanent magnet synchronous servo motor shaft, it collects the motor's speed and position signals and outputs them to the electro-hydraulic actuator controller; Three-phase permanent magnet synchronous servo motor module: Receives the PWM control signal output from the electro-hydraulic actuator controller and drives the connected gear pump to rotate; Gear pump module: Driven by the servo motor, it rotates and outputs hydraulic oil; Hydraulic system component module: includes a hydraulically controlled check valve, a relief valve and a hydraulic cylinder. Hydraulic oil is input to the hydraulic cylinder after being controlled by the hydraulic system component, causing the piston rod to produce linear displacement. Power drive module: Equipped with a SiC MOSFET three-phase full-bridge structure, receiving the output from the electro-hydraulic actuator controller. shaft and The shaft voltage command signal is used to generate a three-phase PWM control signal, which is then output to the servo motor. Current detection module: configured at the input terminal of the electro-hydraulic actuator controller to collect the bus current signal of the servo motor; DC bus voltage detection module: Collects the DC bus voltage value of the system and feeds it back to the electro-hydraulic actuator controller.

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