A compound control method and system for a servo hydraulic device

Abstract

This invention discloses a composite control method and system for a servo hydraulic device, relating to the field of hydraulic control technology. The method involves acquiring the command displacement signal of the servo hydraulic device in the current cycle, calculating the feedforward control voltage based on a nominal dynamic model to obtain a first voltage, acquiring the actual displacement signal of the hydraulic cylinder through a displacement sensor, and subtracting the actual displacement signal from the command displacement signal to obtain the displacement error, calculating the error velocity estimate, error acceleration estimate, and total disturbance estimate based on the displacement error and the previous control cycle, calculating the second voltage based on the error velocity estimate and error acceleration estimate, calculating the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate, and applying the target composite control voltage to the servo valve to drive the hydraulic cylinder movement. This achieves rapid dynamic response and high steady-state control accuracy simultaneously throughout the entire working process.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic control technology, specifically relating to a composite control method and system for servo hydraulic devices. Background Technology

[0002] Servo hydraulic systems, characterized by high power density, rapid response, and high output, are widely used in heavy-duty precision motion control fields such as industrial automation, aerospace, and engineering machinery. These systems typically control the displacement, speed, or force of hydraulic cylinders through servo valves, and their control performance directly determines the machining accuracy, tracking speed, and resistance to external load disturbances of the entire machine. However, servo hydraulic systems inherently exhibit complex characteristics such as nonlinearity, time-varying parameters, and strong external load disturbances, making it difficult for traditional control methods to simultaneously meet both rapid dynamic response and high steady-state accuracy throughout the entire working process.

[0003] Traditional proportional-integral-derivative (PID) controllers are simple in structure, but due to their linear combination based on errors, the contradiction between fast response and overshoot / oscillation is difficult to reconcile. A fixed gain cannot maintain optimal performance under varying operating conditions. To overcome this problem, various methods have been developed, such as model-based feedforward compensation, disturbance observation compensation, and sliding mode control. However, model feedforward uses prior knowledge of the command to drive the actuator in advance, effectively improving the response, but it is highly sensitive to modeling accuracy. Disturbance observers can uniformly estimate and compensate for unmodeled dynamics and external disturbances in the system, but there is a trade-off between noise amplification and disturbance suppression. Sliding mode control is invariant to matching disturbances, but it often faces chattering and convergence speed limitations. For example, CN113232822A discloses a control method and system for a marine servo valve hydraulic steering gear. According to the steering command, a transient process is arranged to obtain the output result of the transient process. According to the output result, the PID controller, which is controlled by proportional, integral, and derivative operations, calculates and outputs the target servo valve opening angle. According to the target servo valve opening angle, the servo valve opening is controlled. However, this solution is still based on traditional PID control logic and has not solved the core problems caused by nonlinearity, time-varying parameters, and strong load disturbances in servo hydraulic systems. It still cannot achieve fast dynamic response and high steady-state control accuracy simultaneously throughout the entire working process. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of not being able to achieve rapid dynamic response and high steady-state control accuracy simultaneously throughout the entire working process, and to propose a composite control method and system for servo hydraulic devices.

[0005] In a first aspect of this invention, a composite control method for a servo hydraulic device is first proposed, the method comprising:

[0006] The command displacement signal of the servo hydraulic device in the current cycle is obtained, and the first voltage is obtained by calculating the feedforward control voltage based on the nominal dynamic model;

[0007] The actual displacement signal of the hydraulic cylinder is obtained by a displacement sensor, and the displacement error is obtained by subtracting the actual displacement signal from the commanded displacement signal.

[0008] Substituting the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer, we obtain the error velocity estimate, the error acceleration estimate, and the total disturbance estimate.

[0009] Based on the error velocity estimate and the error acceleration estimate, the second voltage is calculated by a nonlinear potential field feedback controller.

[0010] The target composite control voltage is calculated based on the first voltage, the second voltage, and the total disturbance estimate; the target composite control voltage is applied to the servo valve to drive the hydraulic cylinder to move.

[0011] The nominal model feedforward is responsible for rapidly driving the actuator using prior knowledge, significantly improving dynamic response. The nonlinear extended state observer treats the unmodeled dynamics of the system, time-varying parameters, and strong load disturbances as a total disturbance for real-time estimation and compensation, fundamentally solving the problems of nonlinearity and disturbance suppression, and avoiding the trade-off between noise amplification and disturbance suppression in traditional disturbance observers. The nonlinear potential field feedback controller, based on error dynamics, synchronously coordinates rapid convergence and overshoot suppression without chattering, breaking the limitation of traditional PID relying solely on linear combination to not be able to balance speed and stability, thus achieving rapid dynamic response and high steady-state control accuracy simultaneously throughout the entire working process.

[0012] Optionally, obtaining the command displacement signal of the servo hydraulic device in the current cycle and calculating the feedforward control voltage based on the nominal dynamic model to obtain the first voltage includes:

[0013] Through formula The first voltage is calculated;

[0014] in, The command velocity is obtained by differentiating the command displacement signal. The command acceleration is obtained by differentiating the command displacement signal. The nominal equivalent mass of the servo hydraulic device is... The viscous damping coefficient of the servo hydraulic device is... The voltage-force conversion gain of the servo hydraulic device.

[0015] Optionally, substituting the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, error acceleration estimate, and total disturbance estimate includes:

[0016] Based on the displacement error, using the formula The displacement observation error value is obtained; where e is the displacement error. This is an estimate of the displacement error;

[0017] To obtain the total disturbance estimate of K from the previous control period Based on the total disturbance estimate and displacement observation error value of K from the previous control cycle, substituting them into the third observer, the result is obtained using the formula... The total disturbance estimate is obtained;

[0018] Where h is the time interval between two adjacent samples. For the third observer gain, It is a nonlinear correction function. For the fal function in The nonlinear exponent in the channel satisfies , The width of the linear region of the fal function;

[0019] Obtain the error acceleration estimate of K from the previous control cycle. Based on the error acceleration estimate of K from the previous control cycle, the composite control voltage calculated from the previous control cycle, the displacement observation error value, and the total disturbance estimate of K from the previous control cycle, these values ​​are substituted into the second observer and calculated using the formula... The error acceleration estimate is obtained;

[0020] in, For the second observer gain, This is the nominal value of the system control gain. The composite control voltage calculated in the previous control cycle; For the fal function in The nonlinear exponent in the channel satisfies ;

[0021] Obtain the error velocity estimate of the previous control cycle K. Based on the error acceleration estimate, error velocity estimate, and displacement observation error value of the previous control cycle K, substitute them into the first observer, and use the formula... The error velocity estimate is obtained; where, This is the gain of the first observer.

[0022] By utilizing the characteristic of the fal function to automatically adjust the gain according to the magnitude of displacement observation error, a high gain is applied when the error is large to quickly track the state, and a low gain is switched when the error is small to smooth noise. This fundamentally avoids the inherent trade-off between fast disturbance estimation and noise amplification in traditional linear disturbance observers. At the same time, the composite control voltage that actually acts on the system is introduced into the observation equation as a known input term, so that the total disturbance estimation can more completely encompass the unmodeled dynamics of the system, parameter perturbations, and strong load disturbances, significantly improving the disturbance observation accuracy. This enables the entire control architecture to achieve active disturbance rejection and fast convergence under varying operating conditions, ensuring the unity of high-frequency dynamic response and high steady-state control accuracy.

[0023] Optionally, the second voltage is calculated by a nonlinear potential field feedback controller based on the error velocity estimate and the error acceleration estimate, including:

[0024] Based on the displacement error, using the formula Calculate the cumulative performance index; where, The cumulative performance index for control period K-1, where h is the time interval between two adjacent samples. To control the displacement error of period k;

[0025] Based on the aforementioned cumulative performance index, using the formula The adaptive gain factor is calculated; where Based on the gain constant, Here, exp is the gain growth coefficient, and exp is the exponential function.

[0026] Based on the aforementioned adaptive gain factor, through the formula The fundamental attraction term of the nonlinear potential field is calculated; where e is the displacement error. For regularization parameters, The constant coefficients, The coefficient of attractive force;

[0027] The second voltage is obtained by correcting and summing the error velocity estimate and the error acceleration estimate based on the fundamental attraction term of the nonlinear potential field.

[0028] By constructing a cumulative performance index and dynamically generating an adaptive gain factor, the controller's feedback strength can be automatically adjusted to follow the accumulation of transient errors in the system. Compared to the shortcomings of traditional PID fixed gain, which cannot adapt to changes in operating conditions, and sliding mode control, which is prone to chattering, this method uses a nonlinear potential field attraction term constructed based on the error velocity and acceleration estimates. This term generates a strong attraction effect during large deviations, achieving rapid convergence, and smoothly degenerates into weak regulation during small deviations to avoid overshoot. Thus, without chattering, it simultaneously coordinates the speed of transient response and the high precision of steady-state control across the entire operating range.

[0029] Optionally, calculating the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate includes:

[0030] The total disturbance estimate is divided by the preset nominal control gain to obtain the disturbance compensation voltage;

[0031] The initial composite control voltage is obtained by summing the first voltage, the second voltage, and the disturbance compensation voltage;

[0032] Based on a preset voltage range, the initial composite control voltage is limited to obtain the target composite control voltage for the current control cycle.

[0033] Total disturbance compensation directly eliminates the effects of unmodeled dynamics, parameter perturbations, and strong load disturbances in the system, physically forcing the servo hydraulic system into a standard nominal model. This frees the traditional PID controller from the constraints of compromising transient performance to suppress disturbances, and avoids the vulnerability of simple model feedforward to high modeling accuracy. Feedforward and feedback each focus on dynamic response optimization and error convergence adjustment on this standardized model, while the final amplitude limiting provides smooth boundary constraints for the control signal, avoiding shock chattering similar to sliding mode control. Globally, this ensures that the servo system has speed, robustness, and high steady-state accuracy across all operating conditions.

[0034] In a second aspect of the invention, a composite control system for a servo hydraulic device is provided, comprising:

[0035] The first voltage calculation module is used to obtain the command displacement signal of the servo hydraulic device in the current cycle and calculate the feedforward control voltage based on the nominal dynamic model to obtain the first voltage.

[0036] The displacement error determination module is used to obtain the actual displacement signal of the hydraulic cylinder through a displacement sensor, and to obtain the displacement error by subtracting the actual displacement signal from the commanded displacement signal.

[0037] The parameter value determination module is used to substitute the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, the error acceleration estimate, and the total disturbance estimate;

[0038] The second voltage calculation module is used to calculate the second voltage based on the error velocity estimate and the error acceleration estimate by a nonlinear potential field feedback controller.

[0039] The target composite control voltage determination module is used to calculate the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate; and to apply the target composite control voltage to the servo valve to drive the hydraulic cylinder to move.

[0040] Optionally, the first voltage calculation module includes:

[0041] Through formula The first voltage is calculated;

[0042] in, The command velocity is obtained by differentiating the command displacement signal. The command acceleration is obtained by differentiating the command displacement signal. The nominal equivalent mass of the servo hydraulic device is... The viscous damping coefficient of the servo hydraulic device is... The voltage-force conversion gain of the servo hydraulic device.

[0043] Optionally, the estimated parameter value determination module includes:

[0044] The displacement observation error determination module is used to determine the displacement error using the formula... The displacement observation error value is obtained; where e is the displacement error. This is an estimate of the displacement error;

[0045] The total disturbance estimate determination module is used to obtain the total disturbance estimate value of K from the previous control cycle. Based on the total disturbance estimate and displacement observation error value of K from the previous control cycle, substituting them into the third observer, the result is obtained using the formula... The total disturbance estimate is obtained;

[0046] Where h is the time interval between two adjacent samples. For the third observer gain, It is a nonlinear correction function. For the fal function in The nonlinear exponent in the channel satisfies , The width of the linear region of the fal function;

[0047] The error acceleration estimation module is used to obtain the error acceleration estimate value of the previous control cycle K. Based on the error acceleration estimate of K from the previous control cycle, the composite control voltage calculated from the previous control cycle, the displacement observation error value, and the total disturbance estimate of K from the previous control cycle, these values ​​are substituted into the second observer and calculated using the formula... The error acceleration estimate is obtained;

[0048] in, For the second observer gain, This is the nominal value of the system control gain. The composite control voltage calculated in the previous control cycle; For the fal function in The nonlinear exponent in the channel satisfies ;

[0049] The error velocity estimation module is used to obtain the error velocity estimate of the previous control cycle K. Based on the error acceleration estimate, the error velocity estimate, and the displacement observation error value of the previous control cycle K, it is substituted into the first observer and calculated using the formula... The error velocity estimate is obtained; where, This is the gain of the first observer.

[0050] Optionally, the second voltage calculation module includes:

[0051] The cumulative performance index determination module is used to determine the cumulative performance index based on the displacement error using the formula. Calculate the cumulative performance index; where, The cumulative performance index for control period K-1, where h is the time interval between two adjacent samples. To control the displacement error of period k;

[0052] The adaptive gain factor determination module is used to determine the gain factor based on the cumulative performance index using a formula. The adaptive gain factor is calculated; where Based on the gain constant, Here, exp is the gain growth coefficient, and exp is the exponential function.

[0053] The nonlinear potential field fundamental attraction term determination module is used to determine the fundamental attraction term based on the adaptive gain factor using the formula... The fundamental attraction term of the nonlinear potential field is calculated; where e is the displacement error. For regularization parameters, The constant coefficients, The coefficient of attractive force;

[0054] The second voltage generation module is used to correct and sum the error velocity estimate and the error acceleration estimate based on the nonlinear potential field fundamental attraction term to obtain the second voltage.

[0055] Optionally, the target composite control voltage determination module includes:

[0056] The disturbance compensation voltage determination module is used to divide the total disturbance estimate by a preset nominal control gain to obtain the disturbance compensation voltage;

[0057] An initial composite control voltage determination module is used to sum the first voltage, the second voltage, and the disturbance compensation voltage to obtain the initial composite control voltage;

[0058] The target composite control voltage determination module is used to limit the initial composite control voltage based on a preset voltage range to obtain the target composite control voltage for the current control cycle.

[0059] The beneficial effects of this invention are:

[0060] This invention proposes a composite control method for servo hydraulic devices. By employing a composite control architecture combining nominal model feedforward, a nonlinear extended state observer, and a nonlinear potential field feedback controller, the overall control performance of the servo hydraulic device is effectively improved. The nominal model feedforward utilizes prior system dynamic information to pre-drive the actuator, significantly enhancing the system's dynamic response and command following capability. The nonlinear extended state observer can uniformly observe and compensate for unmodeled dynamics, time-varying parameters, and strong external load disturbances, effectively suppressing system nonlinearity and the effects of various disturbances, overcoming the problem of mutual constraints between noise amplification and disturbance suppression in traditional observers. The nonlinear potential field feedback controller implements adaptive adjustment based on error dynamics, achieving rapid convergence and overshoot suppression without chattering. This solves the drawback of traditional PID linear control, which struggles to balance dynamic speed and steady-state stability, ensuring that the equipment maintains rapid response and high-precision steady-state control performance throughout the entire operation process. Attached Figure Description

[0061] The invention will now be further described with reference to the accompanying drawings.

[0062] Figure 1 A flowchart of a composite control method for a servo hydraulic device provided in an embodiment of the present invention;

[0063] Figure 2 This is a framework diagram of a composite control system for a servo hydraulic device provided in an embodiment of the present invention. Detailed Implementation

[0064] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0065] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] This invention provides a composite control method for a servo hydraulic device. See also... Figure 1 , Figure 1 A flowchart illustrating a composite control method for a servo hydraulic device provided in an embodiment of the present invention. The method includes the following steps:

[0067] S101, acquire the command displacement signal of the servo hydraulic device in the current cycle, and calculate the feedforward control voltage based on the nominal dynamic model to obtain the first voltage;

[0068] S102: The actual displacement signal of the hydraulic cylinder is obtained through the displacement sensor, and the displacement error is obtained by subtracting the actual displacement signal from the command displacement signal.

[0069] S103, substitute the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, error acceleration estimate and total disturbance estimate;

[0070] S104, based on the error velocity estimate and the error acceleration estimate, the second voltage is calculated by the nonlinear potential field feedback controller;

[0071] S105, calculate the target composite control voltage based on the first voltage, the second voltage and the total disturbance estimate; apply the target composite control voltage to the servo valve to drive the hydraulic cylinder to move.

[0072] In one implementation method, through formula The first voltage is calculated; where, The command velocity is obtained by differentiating the command displacement signal. The instruction acceleration is obtained by differentiating the instruction speed. The nominal equivalent mass of the servo hydraulic unit shall be determined by technical personnel. The viscous damping coefficient of the servo hydraulic device is determined by technical personnel. The voltage-to-force conversion gain of the servo hydraulic device was determined by technical personnel; all formulas in the scheme are purely numerical calculations.

[0073] In one embodiment, substituting the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, error acceleration estimate, and total disturbance estimate includes:

[0074] Based on displacement error, using the formula The displacement observation error value is obtained; where e is the displacement error. This is an estimate of the displacement error;

[0075] To obtain the total disturbance estimate of K from the previous control period Based on the total disturbance estimate and displacement observation error value of K from the previous control cycle, substituting them into the third observer, the result is obtained using the formula... The total disturbance estimate is obtained;

[0076] Where h is the time interval between two adjacent samples. For the third observer gain, It is a nonlinear correction function. For the fal function in The nonlinear exponent in the channel satisfies , The width of the linear region of the fal function;

[0077] Obtain the error acceleration estimate of K from the previous control cycle. Based on the error acceleration estimate of K from the previous control cycle, the composite control voltage calculated from the previous control cycle, the displacement observation error value, and the total disturbance estimate of K from the previous control cycle, these values ​​are substituted into the second observer and calculated using the formula... The error acceleration estimate is obtained;

[0078] in, For the second observer gain, This is the nominal value of the system control gain. The composite control voltage calculated in the previous control cycle; For the fal function in The nonlinear exponent in the channel satisfies ;

[0079] Obtain the error velocity estimate of the previous control cycle K. Based on the error acceleration estimate, error velocity estimate, and displacement observation error value of the previous control cycle K, substitute them into the first observer, and use the formula... The error velocity estimate is obtained; where, This is the gain of the first observer.

[0080] In one implementation, the third observer is located at the outermost loop of the entire observation chain. During updates, it relies only on the disturbance estimate and observation error from the previous cycle and is unaffected by other state variables. Its output directly enters the second observer to compensate for the disturbance in the acceleration estimate and is ultimately converted into a disturbance compensation voltage. The second observer is located in the middle layer of the observation chain. During updates, it integrates the acceleration estimate of the four input quantities from the previous cycle, the system's composite control voltage, the total disturbance estimate from the previous cycle, and the observation error. Its function is to use the known control voltage and disturbance estimate to introduce the forward path information of the system dynamic equations into the observer, which can quickly reflect the true acceleration dynamics under the combined influence of control action and disturbance. The first observer is located in the second layer of the observation chain. During updates, it directly uses the error acceleration estimate just calculated in the current cycle, forming a quasi-forward Euler real-time recursive structure to minimize the phase lag of the velocity estimate.

[0081] In one implementation, through hierarchical compensation decoupling from the third observer to the first observer, the total disturbance estimation first captures the system uncertainty and injects it into the second observer in real time, so that the error acceleration estimation is stripped of disturbance interference at the beginning of generation, thereby recovering a clean error dynamic signal and solving the problem of mutual coupling and contamination of channels in traditional observers.

[0082] In one implementation, the adaptive characteristic of the fal nonlinear function is used to impart high gain when the observation error is large and switch to low gain when the error is small. This enables disturbance estimation and state estimation to quickly track abrupt changes without amplifying steady-state noise, fundamentally reconciling the inherent contradiction between disturbance suppression speed and noise sensitivity in conventional linear observers.

[0083] In one implementation, the composite control voltage of the previous cycle is directly introduced as a known input into the second observer, and the nominal value of the control gain is used to convert it into an equivalent acceleration, so that the observer model is highly consistent with the actual controlled physical process. The known part of the control action is directly used as feedforward information into the estimation chain, and the unknown disturbance part is compensated by the third observer. This significantly improves the error rate and the phase accuracy and convergence speed of the acceleration estimation, and provides low-delay, high-precision state information for subsequent nonlinear potential field feedback control.

[0084] In one embodiment, the second voltage is calculated by a nonlinear potential field feedback controller based on the error velocity estimate and the error acceleration estimate, including:

[0085] Based on displacement error, using the formula Calculate the cumulative performance index; where, The cumulative performance index for control period K-1, where h is the time interval between two adjacent samples. To control the displacement error of period k;

[0086] Based on the cumulative performance index, through the formula The adaptive gain factor is calculated; where Based on the gain constant, Here, exp is the gain growth coefficient, and exp is the exponential function.

[0087] Based on the adaptive gain factor, through the formula The fundamental attraction term of the nonlinear potential field is calculated; where e is the displacement error. For regularization parameters, The constant coefficients, The coefficient of attractive force;

[0088] The second voltage is obtained by correcting and summing the error velocity estimate and error acceleration estimate based on the fundamental attraction term of the nonlinear potential field.

[0089] In one implementation, the basic gain constant, gain growth coefficient, constant coefficient, and attraction intensity coefficient are all determined by technicians; an adaptive gain factor is dynamically generated through cumulative performance indicators, and a potential field attraction term is constructed based on this. The error velocity and acceleration estimates are then corrected and synthesized to form the second voltage.

[0090] In one implementation, the adaptive gain factor adjusts the controller strength in real time based on the historical error accumulation. Under large transient deviations, it automatically increases the attraction to achieve rapid convergence, and under small deviations, it smoothly decreases the gain to eliminate overshoot and oscillation. This fundamentally solves the problems that traditional PID fixed gain cannot adapt to changing operating conditions and that sliding mode control is prone to chattering.

[0091] In one implementation, the potential field is corrected using the error velocity and acceleration estimates, which is equivalent to injecting equivalent damping and inertial adjustment into the attraction term. This allows the error phase trajectory to smoothly approach zero along the optimized path, avoiding the resonance tendency caused by simple proportional adjustment. Under the premise of no chattering and no sacrifice of disturbance rejection capability, the unity of fast transient response and high steady-state control accuracy is achieved simultaneously across the entire operating range.

[0092] In one embodiment, calculating the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate includes:

[0093] Divide the total disturbance estimate by the preset nominal control gain to obtain the disturbance compensation voltage;

[0094] The initial composite control voltage is obtained by summing the first voltage, the second voltage, and the disturbance compensation voltage;

[0095] Based on a preset voltage range, the initial composite control voltage is limited to obtain the target composite control voltage for the current control cycle.

[0096] In one implementation, the total disturbance estimate is directly converted into a disturbance compensation voltage and superimposed in reverse. This is equivalent to canceling all unmodeled dynamics, parameter perturbations and external load disturbances of the system in real time at the physical level, and forcibly correcting the controlled object to the nominal model. This allows the first voltage of feedforward control and the second voltage of feedback control to be designed independently on a clean linearized system, thus resolving the fundamental contradiction that traditional PID is forced to sacrifice transient performance in order to suppress disturbances.

[0097] In one implementation method, through formula Calculations show that Where A is the flow gain of the servo valve, and A is the effective working area of ​​the hydraulic cylinder. The nominal value of the equivalent load mass is determined by technical personnel.

[0098] In one implementation, the initial synthesized voltage is limited to provide a smooth boundary constraint for the output amplitude while preserving the complete disturbance rejection and response capability of the control law, thus preventing actuator saturation and shock and ensuring the safety and smoothness of the system in long-term operation.

[0099] Based on the same inventive concept, embodiments of the present invention also provide a composite control system for a servo hydraulic device. See also Figure 2 , Figure 2 A framework diagram of a composite control system for a servo hydraulic device provided in an embodiment of the present invention includes:

[0100] The first voltage calculation module is used to obtain the command displacement signal of the servo hydraulic device in the current cycle and calculate the feedforward control voltage based on the nominal dynamic model to obtain the first voltage.

[0101] The displacement error determination module is used to obtain the actual displacement signal of the hydraulic cylinder through a displacement sensor, and to obtain the displacement error by subtracting the actual displacement signal from the commanded displacement signal.

[0102] The parameter value determination module is used to substitute the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, the error acceleration estimate, and the total disturbance estimate;

[0103] The second voltage calculation module is used to calculate the second voltage based on the error velocity estimate and the error acceleration estimate by a nonlinear potential field feedback controller.

[0104] The target composite control voltage determination module is used to calculate the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate; and to apply the target composite control voltage to the servo valve to drive the hydraulic cylinder to move.

[0105] Based on the embodiments of the present invention, a composite control system for a servo hydraulic device is provided. The nominal model feedforward is responsible for rapidly driving the actuator using prior knowledge, significantly improving the dynamic response. The nonlinear extended state observer treats the unmodeled dynamics of the system, time-varying parameters, and strong load disturbances as a total disturbance for real-time estimation and compensation, fundamentally solving the problems of nonlinearity and disturbance suppression, and avoiding the trade-off between noise amplification and disturbance suppression in traditional disturbance observers. The nonlinear potential field feedback controller, based on error dynamics, synchronously coordinates rapid convergence and overshoot suppression without chattering, breaking the limitation of traditional PID relying solely on linear combination to not simultaneously achieve both speed and stability. Thus, it synchronously achieves rapid dynamic response and high steady-state control accuracy throughout the entire working process.

[0106] The foregoing has described one embodiment of the present invention in detail, but this content is merely a preferred embodiment and should not be considered as limiting the scope of the present invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the scope of the claims of this invention.

Claims

1. A compound control method for a servo hydraulic device, characterized by, The method includes: The command displacement signal of the servo hydraulic device in the current cycle is obtained, and the first voltage is obtained by calculating the feedforward control voltage based on the nominal dynamic model; The actual displacement signal of the hydraulic cylinder is obtained by a displacement sensor, and the displacement error is obtained by subtracting the actual displacement signal from the commanded displacement signal. Substituting the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer, we obtain the error velocity estimate, the error acceleration estimate, and the total disturbance estimate. Based on the error velocity estimate and the error acceleration estimate, the second voltage is calculated by a nonlinear potential field feedback controller. The target composite control voltage is calculated based on the first voltage, the second voltage, and the total disturbance estimate; the target composite control voltage is applied to the servo valve to drive the hydraulic cylinder to move.

2. The compound control method for a servo hydraulic device according to claim 1, wherein Obtain the command displacement signal of the servo hydraulic device in the current cycle, and calculate the feedforward control voltage based on the nominal dynamic model to obtain the first voltage, including: The first voltage is calculated by the formula V1 = V2 - V3 in, The command velocity is obtained by differentiating the command displacement signal. The command acceleration is obtained by differentiating the command displacement signal. The nominal equivalent mass of the servo hydraulic device is... The viscous damping coefficient of the servo hydraulic device is... The voltage-force conversion gain of the servo hydraulic device.

3. The method of claim 1, wherein the method further comprises: Substituting the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer, we obtain the error velocity estimate, error acceleration estimate, and total disturbance estimate, including: Based on the displacement error, the displacement observation error value is obtained by formula wherein e is the displacement error, is the estimated value of the displacement error. To obtain the total disturbance estimate of K from the previous control period Based on the total disturbance estimate and displacement observation error value of K from the previous control cycle, substituting them into the third observer, the result is obtained using the formula... The total disturbance estimate is obtained; Where h is the time interval between two adjacent samples. For the third observer gain, It is a nonlinear correction function. For the fal function in The nonlinear exponent in the channel satisfies , The width of the linear region of the fal function; Obtain the error acceleration estimate of K from the previous control cycle. Based on the error acceleration estimate of K from the previous control cycle, the composite control voltage calculated from the previous control cycle, the displacement observation error value, and the total disturbance estimate of K from the previous control cycle, these values ​​are substituted into the second observer and calculated using the formula... The error acceleration estimate is obtained; in, For the second observer gain, This is the nominal value of the system control gain. The composite control voltage calculated in the previous control cycle; For the fal function in The nonlinear exponent in the channel satisfies ; An error speed estimation value of a previous control period K is obtained, and based on an error acceleration estimation value of the previous control period K, the error speed estimation value of the previous control period K and a displacement observation error value, the first observer is substituted by the formula to obtain an error speed estimation value; wherein, is a first observer gain.

4. The method of claim 1, wherein Based on the error velocity estimate and the error acceleration estimate, the second voltage is calculated by the nonlinear potential field feedback controller, including: Based on the displacement error, a cumulative performance indicator is calculated by the formula wherein, is the cumulative performance indicator for control period K-1, h is the time interval between two adjacent samplings, is the displacement error for control period k; Based on the cumulative performance index, an adaptive gain factor is calculated by the formula wherein is a base gain constant, is a gain growth coefficient, and exp is the exponential function. Based on the aforementioned adaptive gain factor, through the formula The fundamental attraction term of the nonlinear potential field is calculated; where e is the displacement error. For regularization parameters, The constant coefficients, The coefficient of attractive force; The second voltage is obtained by correcting and summing the error velocity estimate and the error acceleration estimate based on the fundamental attraction term of the nonlinear potential field.

5. A composite control method for a servo hydraulic device according to claim 1, characterized in that, The target composite control voltage is calculated based on the first voltage, the second voltage, and the total disturbance estimate, including: The total disturbance estimate is divided by the preset nominal control gain to obtain the disturbance compensation voltage; The initial composite control voltage is obtained by summing the first voltage, the second voltage, and the disturbance compensation voltage; Based on a preset voltage range, the initial composite control voltage is limited to obtain the target composite control voltage for the current control cycle.

6. A compound control system for a servo-hydraulic device, characterized by The system includes: The first voltage calculation module is used to obtain the command displacement signal of the servo hydraulic device in the current cycle and calculate the feedforward control voltage based on the nominal dynamic model to obtain the first voltage. The displacement error determination module is used to obtain the actual displacement signal of the hydraulic cylinder through a displacement sensor, and to obtain the displacement error by subtracting the actual displacement signal from the commanded displacement signal. The parameter value determination module is used to substitute the displacement error and the composite control voltage calculated in the previous control cycle into the nonlinear extended state observer to obtain the error velocity estimate, the error acceleration estimate, and the total disturbance estimate; The second voltage calculation module is used to calculate the second voltage based on the error velocity estimate and the error acceleration estimate by a nonlinear potential field feedback controller. The target composite control voltage determination module is used to calculate the target composite control voltage based on the first voltage, the second voltage, and the total disturbance estimate; and to apply the target composite control voltage to the servo valve to drive the hydraulic cylinder to move.

7. A compound control system for a servo-hydraulic device according to claim 6, wherein, The first voltage calculation module includes: The first voltage is calculated by the formula V1 = V2 - V3 in, The command velocity is obtained by differentiating the command displacement signal. The command acceleration is obtained by differentiating the command displacement signal. The nominal equivalent mass of the servo hydraulic device is... The viscous damping coefficient of the servo hydraulic device is... The voltage-force conversion gain of the servo hydraulic device.

8. A compound control system for a servo-hydraulic device according to claim 6, wherein, The module for determining the estimated parameter values ​​includes: The displacement observation error value determination module is configured to obtain a displacement observation error value based on the displacement error by a formula where e is the displacement error, is an estimated value of the displacement error. The total disturbance estimation value determination module is configured to obtain a total disturbance estimation value of a previous control period K , and substitute the total disturbance estimation value of the previous control period K and the displacement observation error value into a third observer to obtain a total disturbance estimation value through a formula . Where h is the time interval between two adjacent samples. For the third observer gain, It is a nonlinear correction function. For the fal function in The nonlinear exponent in the channel satisfies , The width of the linear region of the fal function; The error acceleration estimation module is used to obtain the error acceleration estimate value of the previous control cycle K. Based on the error acceleration estimate of K from the previous control cycle, the composite control voltage calculated from the previous control cycle, the displacement observation error value, and the total disturbance estimate of K from the previous control cycle, these values ​​are substituted into the second observer and calculated using the formula... The error acceleration estimate is obtained; in, For the second observer gain, This is the nominal value of the system control gain. The composite control voltage calculated in the previous control cycle; For the fal function in The nonlinear exponent in the channel satisfies ; The error velocity estimation module is used to obtain the error velocity estimate of the previous control cycle K. Based on the error acceleration estimate, the error velocity estimate, and the displacement observation error value of the previous control cycle K, it is substituted into the first observer and calculated using the formula... The error velocity estimate is obtained; where, This is the gain of the first observer.

9. A composite control system for a servo hydraulic device according to claim 6, characterized in that, The second voltage calculation module includes: The cumulative performance index determination module is used to determine the cumulative performance index based on the displacement error using the formula. Calculate the cumulative performance index; where, The cumulative performance index for control period K-1, where h is the time interval between two adjacent samples. To control the displacement error of period k; The adaptive gain factor determination module is used to determine the gain factor based on the cumulative performance index using a formula. The adaptive gain factor is calculated; where Based on the gain constant, Here, exp is the gain growth coefficient, and exp is the exponential function. The nonlinear potential field fundamental attraction term determination module is used to determine the fundamental attraction term based on the adaptive gain factor using the formula... The fundamental attraction term of the nonlinear potential field is calculated; where e is the displacement error. For regularization parameters, The constant coefficients, The coefficient of attractive force; The second voltage generation module is used to correct and sum the error velocity estimate and the error acceleration estimate based on the nonlinear potential field fundamental attraction term to obtain the second voltage.

10. A composite control system for a servo hydraulic device according to claim 6, characterized in that, The target composite control voltage determination module includes: The disturbance compensation voltage determination module is used to divide the total disturbance estimate by a preset nominal control gain to obtain the disturbance compensation voltage; An initial composite control voltage determination module is used to sum the first voltage, the second voltage, and the disturbance compensation voltage to obtain the initial composite control voltage; The target composite control voltage determination module is used to limit the initial composite control voltage based on a preset voltage range to obtain the target composite control voltage for the current control cycle.

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