High-precision and high-robustness control method for EHA online disturbance monitoring suppression

Abstract

The invention discloses a high-precision and high-robustness control method for EHA online disturbance monitoring suppression. The method comprises the following steps that displacement, motor rotating speed and current signals are collected in real time through a sensor; estimating the speed, pressure and matching disturbance of the actuator cylinder by using a state extension observer, and obtaining mismatching disturbance through a nonlinear disturbance observer; the system is divided into an execution subsystem, a hydraulic subsystem and a motor subsystem based on virtual decomposition control, and expected pressure, expected angular velocity and expected current are output respectively; the execution subsystem generates expected pressure in combination with a displacement instruction, speed estimation and matched disturbance, the hydraulic subsystem integrates the expected pressure and the mismatched disturbance to calculate expected angular velocity, and the motor subsystem outputs expected current according to the expected angular velocity and the expected pressure; and state parameters are circularly updated to realize dynamic optimization. According to the method, through multi-stage disturbance observation and virtual decoupling control, the problems of strong nonlinearity, complex disturbance and the like of the EHA are effectively solved, and high-precision and high-robustness motion control under all working conditions is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic transmission and control, in particular to the technical field of an EHA online disturbance monitoring and suppression high-precision and high-robustness control method. Background Art

[0002] As a highly integrated pump-controlled hydraulic system, the electro-hydrostatic actuator (EHA) is widely used in aerospace actuation systems, precision engineering machinery, robotics, and high-end industrial equipment due to its advantages, including high power density, compact size, high energy efficiency, and strong reliability. Compared with traditional valve-controlled hydraulic systems, the EHA directly regulates the pump's speed or displacement to drive the actuator, eliminating throttling losses and the drawbacks of centralized oil supply, significantly improving system efficiency. However, the EHA is inherently a nonlinear system with strong coupling of multiple physical fields. The dynamic characteristics of its core components (such as the motor, hydraulic pump, and actuator) are influenced by complex nonlinear factors, including the compressibility of the hydraulic fluid, friction nonlinearity, the time-varying elastic modulus of the oil, and temperature-sensitive parameter drift. Furthermore, during operation, the EHA must cope with various disturbances, such as internal flow shocks and oil parameter fluctuations (matching disturbances) as well as external load abrupt changes and vibration disturbances (mismatching disturbances). These nonlinearities and disturbances severely limit the control accuracy, dynamic response, and robustness of the EHA, becoming a major bottleneck for its application in high-precision scenarios.

[0003] Existing technologies have proposed a variety of strategies to address the nonlinear control issues of EHA. For example, robust control based on parameter adaptation compensates for uncertainty by adjusting controller parameters online, but suffers from insufficient stability under strong disturbances. Sliding mode control, while highly robust, suffers from high-frequency chattering, which hinders practical engineering applications. Virtual decomposition control (VDC) simplifies the design by decoupling subsystems, but has limited ability to suppress the combined effects of multiple disturbances. Furthermore, feedback linearization and adaptive integral robust control compensate for motor magnetic circuit nonlinearities and hydraulic pump pressure fluctuations, respectively, but fail to systematically address the synergistic effects of internal and external disturbances. Regarding disturbance suppression, existing methods often focus on a single disturbance type: for example, linear extended observers compensate for internal leakage and friction, and backstepping controllers address external load disturbances. However, these methods lack the ability to simultaneously observe and actively suppress both matched and mismatched disturbances, leading to significant control errors under complex operating conditions (such as motor reversal and sudden load changes).

[0004] More critically, existing control methods generally rely on high-order nonlinear algorithms. While these methods theoretically improve accuracy, they lead to complex controller structures, difficult parameter tuning, and difficulty verifying global convergence through rigorous validation of theories such as Lyapunov stability. Furthermore, traditional observers are unable to simultaneously estimate the system state and multiple types of disturbances, resulting in delayed or undercompensated disturbance compensation, further limiting control bandwidth and dynamic performance.

[0005] Therefore, there is an urgent need for an EHA control method that can monitor and coordinately suppress matching and mismatching disturbances online in real time, and take into account both high precision and strong robustness, so as to break through the limitations of existing technologies in multi-disturbance coupling, nonlinear time-varying and engineering practicality, and meet the application needs of high-demand scenarios such as aviation actuation. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems in the prior art and propose an EHA online disturbance monitoring and suppression high-precision and high-robust control method. It can completely solve the problems of flow mismatch, strong nonlinearity, and complex disturbance in the control of the electrostatic hydraulic actuator without increasing the weight, volume, and additional auxiliary sensors of the electrostatic hydraulic actuator, and realize high-precision and high-robust motion control of the electrostatic hydraulic actuator under different motion conditions.

[0007] To achieve the above objectives, the present invention proposes a high-precision, high-robust control method for EHA online disturbance monitoring and suppression. The system includes a controller, a motor, a hydraulic pump, an accumulator, an asymmetric actuator, and a sensing system. The controller and motor are electrically connected, and the motor output is connected to the hydraulic pump. The sensing system includes a current sensor, a resolver, and a displacement sensor. The current sensor measures the motor current, the resolver measures the motor speed, and the displacement sensor measures the displacement of the asymmetric actuator.

[0008] The control method includes an observer module and a virtual decomposition control module. The observer module can estimate the actuator speed, pressure, and match and mismatch disturbances of the electrostatic hydraulic actuator system in real time. The virtual decomposition control module uses the results obtained by the observer as input and outputs the current required by the motor to achieve precise control.

[0009] The observer module includes an extended state observer and a nonlinear disturbance observer. The extended state observer is used to estimate the system state (such as actuator speed and pressure) and matching disturbances (such as flow shock and oil elastic modulus change), and the nonlinear disturbance observer is used to estimate mismatch disturbances (such as external load changes).

[0010] The virtual decomposition control module divides the electrostatic-hydraulic actuator into three subsystems for controller design: the actuator subsystem, the hydraulic subsystem, and the motor subsystem. The actuator subsystem requires inputs of the actuator displacement, the actuator cylinder velocity, and the matching disturbance. These control variables are provided by the displacement sensor and the linear expansion observer, respectively. The actuator subsystem outputs the required pressure of the electrostatic-hydraulic actuator. The hydraulic subsystem requires inputs of the required and actual pressure of the electrostatic-hydraulic actuator, the required and actual speed of the actuator cylinder, and the mismatch disturbance. The actuator subsystem provides the required speed and pressure of the actuator cylinder, the linear expansion observer provides the actual pressure and speed, and the nonlinear disturbance observer provides the mismatch disturbance. The hydraulic subsystem outputs the required angular velocity of the motor. The motor subsystem requires inputs of the required and actual motor angular velocity, the required pressure, and the actual pressure. The hydraulic subsystem provides the required angular velocity of the motor, the resolver provides the actual angular velocity, the actuator subsystem provides the required pressure, and the linear expansion observer provides the actual pressure.

[0011] Then, using the actuator displacement and motor speed as input, the Extended State Observer (ESO) and Nonlinear Disturbance Observer (NDO) provide the controller with real-time information such as system state variables, matched disturbances, and mismatched disturbances. Finally, by compensating for matched and mismatched disturbances, the controller achieves fast response and strong robustness.

[0012] The EHA online disturbance monitoring and suppression high-precision and high-robust control method is characterized by comprising the following steps: Step 1: Collect the displacement signal of the electrostatic hydraulic actuator in real time through the electrostatic hydraulic actuator sensor system , motor speed signal and motor current signal ; Step 2: Convert the displacement signal and motor speed signal Input to the Extended State Observer (ESO), output actuator velocity estimate , pressure estimate and the estimated value of the matching disturbance ; Step 3: Estimated actuator speed Input to the nonlinear disturbance observer (NDO), which outputs an estimate of the mismatch disturbance ; Step 4: Based on the virtual decomposition control (VDC) method, the electrostatic hydraulic actuator is virtually decomposed into an actuator subsystem, a hydraulic subsystem, and a motor subsystem; Step 5: The execution subsystem receives the displacement value of the actuator , actuator position command value , estimated actuator speed and matching disturbance estimates , calculate and output the system expected pressure value ; Step 6: The hydraulic subsystem receives the actuator displacement value , expected pressure value , estimated actuator speed and mismatch disturbance estimates , calculate and output the desired angular velocity of the motor ; Step 7: The motor subsystem receives the motor angular velocity , desired angular velocity , expected pressure value and pressure estimates , calculate and output the motor expected current ; Step 8: Update the actuator displacement and motor angular velocity, and repeat steps 1 to 7 to form a closed-loop control.

[0013] The mathematical model of the extended state observer (ESO) is:

[0014] in, is an adjustable parameter and , is the mismatch disturbance estimate.

[0015] The mathematical model of the nonlinear disturbance observer (NDO) is:

[0016] in, is an adjustable parameter and .

[0017] The required speed of the actuator subsystem will be:

[0018] in, is the desired displacement of the electrostatic hydraulic actuator, is the displacement feedback gain and ; The control law of the execution subsystem is:

[0019] in, is the desired pressure of the actuator, is the desired acceleration, is the local feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the working area of ​​the rodless chamber and the working area of ​​the rod chamber of the actuator, is the inertial mass of the load.

[0020] The control law of the hydraulic subsystem is:

[0021] in, is the desired speed of the motor, is the local feedback gain and , To stabilize the feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the working area of ​​the rodless chamber and the working area of ​​the rod chamber of the actuator, and They are the pump's A port displacement and B port displacement, is the initial position of the piston, is the elastic modulus of the oil, and are the internal leakage coefficients of the pump and actuator, respectively.

[0022] The control law of the motor subsystem is:

[0023] in, is the desired current of the motor and is related to equal, is the local feedback gain and , To stabilize the feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the displacement of port A and port B of the pump respectively.

[0024] The matching disturbance includes the change of oil elastic modulus and flow impact, and the mismatch disturbance includes the change of external load and friction nonlinear effect.

[0025] Beneficial effects of the present invention: 1. An extended state observer and a nonlinear disturbance observer are designed to estimate the system state, mismatch disturbance and match disturbance without adding auxiliary sensors.

[0026] 2. Using a virtual decomposition control method, the electrostatic hydraulic actuator is virtually decomposed into actuator, hydraulic, and motor subsystems, and controllers are designed for each of them. A local decentralized controller is designed at the subsystem level, fully considering the dynamic interaction between adjacent subsystems to ensure system stability and improve system robustness and bandwidth.

[0027] 3. Combining component structure optimization with high-performance control methods, the problems of flow field mismatch, strong nonlinearity, and complex disturbances existing in the control of electrostatic hydraulic actuators are completely solved, and high-precision robust trajectory tracking control of electrostatic hydraulic actuators under different motion conditions is achieved.

[0028] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the electrostatic hydraulic actuator of the EHA online disturbance monitoring and suppression high-precision and high-robust control method of the present invention; Figure 2 This is a control system schematic diagram of the EHA online disturbance monitoring and suppression high-precision and high-robust control method of the present invention; Figure 3 Schematic diagram of four control methods of the EHA online disturbance monitoring and suppression high-precision and high-robust control method of the present invention; Figure 4 1 is a graph showing the test results of the high-precision and high-robust control method for EHA online disturbance monitoring suppression under sinusoidal conditions of the present invention; Figure 5 This is a test result diagram of the EHA online disturbance monitoring and suppression high-precision and high-robust control method under step conditions of the present invention.

[0030] In the figure: a controller, a motor, a hydraulic pump, an asymmetric actuator and a sensing system; the sensing system includes a current sensor, a rotary transformer and a displacement sensor, wherein the current sensor collects the current of the motor, the rotary transformer collects the speed of the motor, and the displacement sensor collects the displacement of the asymmetric actuator. DETAILED DESCRIPTION

[0031] See Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 , the present invention comprises the following steps: Step 1: Collect the displacement signal of the electrostatic hydraulic actuator in real time through the electrostatic hydraulic actuator sensor system , motor speed signal and motor current signal ; Step 2: Convert the displacement signal and motor speed signal Input to the Extended State Observer (ESO), output actuator velocity estimate , pressure estimate and the estimated value of the matching disturbance ; Step 3: Estimated actuator speed Input to the nonlinear disturbance observer (NDO), which outputs an estimate of the mismatch disturbance ; Step 4: Based on the virtual decomposition control (VDC) method, the electrostatic hydraulic actuator is virtually decomposed into an actuator subsystem, a hydraulic subsystem, and a motor subsystem; Step 5: The execution subsystem receives the displacement value of the actuator , actuator position command value , estimated actuator speed and matching disturbance estimates , calculate and output the system expected pressure value ; Step 6: The hydraulic subsystem receives the actuator displacement value , expected pressure value , estimated actuator speed and mismatch disturbance estimates , calculate and output the desired angular velocity of the motor ; Step 7: The motor subsystem receives the motor angular velocity , desired angular velocity , expected pressure value and pressure estimates , calculate and output the motor expected current ; Step 8: Update the actuator displacement and motor angular velocity, and repeat steps 1 to 7 to form a closed-loop control.

[0032] Working process of the present invention: The working process of the EHA online disturbance monitoring and suppression high-precision and high-robust control method of the present invention is explained with reference to the accompanying drawings.

[0033] The electrostatic-hydraulic actuator (ESA) is a complex, multi-component, multi-physics system. Due to the complex flow characteristics of the pump and the compressibility of the hydraulic fluid, ESAs exhibit strong nonlinearities in their flow and pressure dynamics. Furthermore, the internal oil temperature fluctuates during actual ESA operation, leading to variations in the oil's elastic modulus, leakage in the pump and cylinder, the actual volume of the two oil chambers in the actuator, and internal friction during cylinder switching, further exacerbating the nonlinearity. Furthermore, ESAs inevitably encounter various disturbances during actual operation, including external disturbances (such as load disturbances) and internal disturbances (such as flow shock and variations in the oil's elastic modulus). These strong nonlinearities and the influence of these disturbances significantly degrade the ESA's control performance, resulting in low control accuracy, slow frequency response, and poor robustness. Conventional methods are unable to meet these requirements.

[0034] In response to the above specific work, the electrostatic-hydraulic actuator control method based on matching and mismatch disturbance suppression proposed in the present invention can estimate the system state, mismatch disturbance and matching disturbance without adding auxiliary sensors, completely solving the problems of flow field mismatch, strong nonlinearity, complex disturbance and so on in the control of electrostatic-hydraulic actuator, and realizing high-precision robust trajectory tracking control of the electrostatic-hydraulic actuator under different motion conditions.

[0035] The specific steps are as follows: Modeling of electrostatic hydraulic actuator system: Motor torque balance equation: (1) in is the moment of inertia of the motor pump, is the friction coefficient of the motor, is the load torque, is the torque coefficient.

[0036] As a pump control system, the hydraulic system of the electrostatic hydraulic actuator can be described as: (2) (3) in, and is the switching coefficient of the actuator extension and retraction, the specific value is shown in Table 1; and They are the working area of ​​the rodless cavity and the working area of ​​the rod cavity of the actuator respectively; and They are the pump's A port displacement and B port displacement, is the displacement of the actuator, is the speed of the actuator, is the acceleration of the actuator, is the initial position of the piston, is the elastic modulus of the oil, and are the internal leakage coefficients of the pump and actuator, is the inertial mass of the load, is the damping coefficient of the load, It is the external load force. , is the continuous friction model, where and are static friction and Coulomb friction, is the critical speed, is the coefficient of viscous friction.

[0037] Table 1 Working mode selection

[0038] (2) Design of extended state observer and nonlinear disturbance observer The electrostatic-hydraulic actuator (ESA) is a complex, multi-subsystem, multi-physics system with strong nonlinearity. Due to the complex flow characteristics of the pump and the compressibility of the hydraulic fluid, the ESA exhibits strong nonlinear characteristics in terms of fluid and pressure dynamics. Furthermore, during actual operation, the ESA inevitably encounters various disturbances, including external disturbances (such as load and vibration) and internal disturbances (such as flow shock and changes in the elastic modulus of the oil). The strong nonlinearity and the influence of various disturbances will significantly reduce the actual control performance of the ESA. To address these issues, an extended state observer and nonlinear disturbance observer for the ESA were designed. These observers can accurately estimate the system state, mismatch disturbances, and match disturbances online without adding auxiliary sensors.

[0039] By combining the above equations and ignoring the external leakage of the pump and cylinder, the state space equation of the improved electrostatic actuator can be constructed as (4) represents the system state variables, , , , , , , are parameters that can be calculated from known physical parameters. and is defined as a term containing parameter uncertainty and can be expressed as (5) definition As an external disturbance in the actual operation of the electrostatic hydraulic actuator, As the concentrated disturbance caused by the inevitable modeling uncertainty. So the state equation can be rewritten as: (6) In the equation, is regarded as a mismatch disturbance, Considered as a mismatch disturbance. During actual operation of an electrostatic hydraulic actuator, ambient temperature, oil temperature, and other temperatures are constantly changing, and electrostatic hydraulic actuator components are subject to continuous wear. These factors can cause significant variations in parameters such as the oil's elastic modulus and leakage coefficient. Because subsequent controller designs utilize fixed parameter values, this invention categorizes all disturbances caused by parameter deviations as mismatch disturbances and mismatch disturbances.

[0040] The goal of electrostatic hydraulic actuator control is to ensure that the cylinder output position tracks the desired position trajectory as accurately as possible under various motion conditions while overcoming the effects of mismatch and match disturbances. Before designing the controller, the following assumptions must be established.

[0041] Assumption 1: When the electrostatic hydraulic actuator is actually working, the load pressure is bounded and less than the maximum pressure that the system can withstand; Assumption 2: The matching disturbance and the mismatching disturbance are bounded, and the boundaries of the disturbances are known constants; Although most existing state observers can be used to observe unknown state variables in electrostatic hydraulic actuators, such as position, cylinder velocity, and load pressure, they are unable to estimate mismatch and match disturbances. In the present invention, two observers, namely ESO and NDO, are specifically designed to estimate match and mismatch disturbances. In addition, the controller will use the estimated results of the observers to perform disturbance compensation to achieve more accurate and robust position trajectory tracking. In the present invention, for the sake of convenience, we will refer to and Abbreviated as and , unless otherwise stated. The spatial state equation can be rewritten as: (7) is the state variable of the extended observer.

[0042] definition yes The estimated value of As the estimated error value. The extended observer can be written as: (8) In the formula It is an adjustable parameter. yes From the above formula, ESO needs to know in real time Therefore, NDO is designed to estimate the value of A helper variable Designed to (9) It is an adjustable parameter.

[0043] According to the above formula, The derivative of can be expressed as: (10) Similarly, Expressed as The estimated value of As Therefore, the above formula can be further expressed as: (11) Then we can get Estimated value of: (12) (3) Virtual decomposition controller design The virtual decomposition control (VDC) method is a control method based on nonlinear models, which has been proven to be very effective in complex multi-subsystem nonlinear systems. The basic idea of ​​the virtual decomposition control method is to virtually decompose the target system into multiple modular subsystems. Then, a local decentralized controller is designed at the subsystem level, fully considering the dynamic interaction between adjacent subsystems to ensure the stability of the system; the present invention divides the electrostatic hydraulic actuator into three subsystems for controller design, namely the actuator subsystem, the hydraulic subsystem and the motor subsystem. Then, with the actuator displacement and motor speed as input, ESO and NDO provide the controller with real-time information such as system state variables, matching disturbances and mismatching disturbances. Finally, by compensating for matching and mismatching disturbances, the controller has fast response capability and strong robustness. The overall schematic diagram of the proposed control method is shown in the figure. Figure 2 As shown. Next, the control strategy of each subsystem is introduced respectively: 1) Actuator subsystem Required speed is replaced by the required speed

[0044] (13) Where, is the desired displacement of the electrostatic hydraulic actuator, Displacement feedback gain, combined with the above formula, the execution subsystem can be expressed as: (14) Where, is the desired pressure of the actuator, is the desired acceleration, is the local feedback gain.

[0045] 2) Hydraulic subsystem Integrating the above formula, the hydraulic subsystem can be expressed as: (15) In the formula is the desired speed of the motor, is the local feedback gain, is the stabilizing feedback gain.

[0046] 3) Motor subsystem (16) is the desired current of the motor, which is equal to , is the local feedback gain, is the stabilizing feedback gain.

[0047] The parameters of the components of the electrostatic hydraulic actuator system are shown in the following table: Table 2 Electrostatic hydraulic actuator system parameter settings

[0048] Test results and discussion: Based on the electrostatic hydraulic actuator system and test bench, four different controllers are compared to demonstrate the superiority of the proposed controller, e.g. Figure 3 The details of the different controllers are described below.

[0049] (1) Use a well-tuned PID controller as a basis to verify the performance of other controllers. The controller is divided into position loop, velocity loop, and current loop. The position loop controls the displacement of the actuator, the velocity loop controls the speed of the motor, and the current loop controls the current of the motor.

[0050] (2) VDC is a controller that does not consider continuous friction compensation, matching disturbance and mismatch disturbance compensation. In order to verify the effectiveness of the continuous friction compensation module.

[0051] (3) Output Feedback Virtual Decomposition Controller (OFVDC) is a controller that does not consider matching and mismatching disturbance compensation. In order to verify the necessity of ESO and NDO.

[0052] (4) The output full feedback virtual decomposition controller (OFFVDC) is the controller recommended by this invention, which includes continuous friction compensation, matching and mismatch disturbance compensation.

[0053] The parameter settings of the four controllers are shown in Table 3.

[0054] Table 3 Parameter settings of different controllers

[0055] In this paper, the position tracking performance of the proposed OFFVDC is verified by using two different motion tests, namely, a sinusoidal motion test and a step motion test.

[0056] Case 1: Sinusoidal motion. The controller tracks a smooth normal motion trajectory. mm, . The performance of each controller is as follows Figure 4 shown.

[0057] Case 2: Step motion. To verify the fast response performance of the electrostatic hydraulic actuator, a square wave trajectory with an amplitude of 10 mm and a frequency of 0.25 Hz was proposed. At 5 seconds, there was an external load of 30,000 N. The performance of each controller is as follows: Figure 5 shown.

[0058] from Figure 4 、 Figure 5 It can be seen that the control method proposed in the present invention can obtain the unmeasurable system state in real time, while suppressing a large amount of unknown matching and mismatching interference, so that the system has higher control accuracy and robustness.

[0059] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. EHA online disturbance monitoring and suppression high-precision and high-robust control method, characterized by: The following steps are involved: Step 1: Collect the displacement signal of the electrostatic hydraulic actuator in real time through the electrostatic hydraulic actuator sensor system , motor speed signal and motor current signal ; Step 2: Convert the displacement signal and motor speed signal Input to the Extended State Observer (ESO), output actuator velocity estimate , pressure estimate and the estimated value of the matching disturbance ; Step 3: Estimated actuator speed Input to the nonlinear disturbance observer (NDO), which outputs an estimate of the mismatch disturbance ; Step 4: Based on the virtual decomposition control (VDC) method, the electrostatic hydraulic actuator is virtually decomposed into an actuator subsystem, a hydraulic subsystem, and a motor subsystem; Step 5: The execution subsystem receives the displacement value of the actuator , actuator position command value , estimated actuator speed and matching disturbance estimates , calculate and output the system expected pressure value ; Step 6: The hydraulic subsystem receives the actuator displacement value , expected pressure value , estimated actuator speed and mismatch disturbance estimates , calculate and output the desired angular velocity of the motor ; Step 7: The motor subsystem receives the motor angular velocity , desired angular velocity , expected pressure value and pressure estimates , calculate and output the expected motor current ; Step 8: Update the actuator displacement and motor angular velocity, and repeat steps 1 to 7 to form a closed-loop control.

2. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The mathematical model of the extended state observer (ESO) is: in, is an adjustable parameter and , is the mismatch disturbance estimate.

3. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The mathematical model of the nonlinear disturbance observer (NDO) is: in, is an adjustable parameter and .

4. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The required speed of the actuator subsystem will be: in, is the desired displacement of the electrostatic hydraulic actuator, is the displacement feedback gain and ; The control law of the execution subsystem is: in, is the desired pressure of the actuator, is the desired acceleration, is the local feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the working area of ​​the rodless chamber and the working area of ​​the rod chamber of the actuator, is the inertial mass of the load.

5. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The control law of the hydraulic subsystem is: in, is the desired speed of the motor, is the local feedback gain and , To stabilize the feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the working area of ​​the rodless chamber and the working area of ​​the rod chamber of the actuator, and They are the displacement of port A and port B of the pump, is the initial position of the piston, is the elastic modulus of the oil, and are the internal leakage coefficients of the pump and actuator, respectively.

6. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The control law of the motor subsystem is: in, is the desired current of the motor and is related to equal, is the local feedback gain and , To stabilize the feedback gain and , and is the switching coefficient of the actuator extension and retraction, and They are the displacement of port A and port B of the pump respectively.

7. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The sensor system includes: a displacement sensor, a rotary transformer and a current sensor, which are respectively used to collect actuator displacement, motor speed and motor current signals.

8. The EHA online disturbance monitoring and suppression high-precision and high-robust control method according to claim 1 is characterized by: The matching disturbance includes the change of oil elastic modulus and flow impact, and the mismatch disturbance includes the change of external load and friction nonlinear effect.

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