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CN-121977001-A - Hydraulic system preset time self-adaptive intelligent control method

CN121977001ACN 121977001 ACN121977001 ACN 121977001ACN-121977001-A

Abstract

The invention discloses a hydraulic system preset time self-adaptive intelligent control method, in particular to a preset time self-adaptive neural network method for processing uncertain nonlinearity in a hydraulic system, and meanwhile, the method is used for developing the uncertainty of preset time self-adaptive law processing parameters, and finally, the preset time self-adaptive intelligent control method capable of efficiently processing the nonlinearity of the hydraulic system is formed. Aiming at the problem of position control of a hydraulic cylinder of a hydraulic system, the invention ensures the excellent transient performance of the system in the preset time and the excellent steady-state performance after the preset time through effectively processing the uncertain nonlinearity, and the convergence time can be definitely determined and is independent of the initial condition of the system.

Inventors

  • YANG XIAOWEI
  • LI PENGFEI
  • YAO JIANYONG
  • YU XIAOCHUAN

Assignees

  • 南京理工大学

Dates

Publication Date
20260505
Application Date
20260409

Claims (9)

  1. 1. The self-adaptive intelligent control method for the preset time of the hydraulic system is characterized by comprising the following steps of: step1, establishing a mathematical model of a hydraulic system, , Wherein m represents the mass of the load, y represents the displacement of the piston rod of the hydraulic cylinder, Indicating the speed of the hydraulic cylinder piston rod, Indicating the acceleration of a piston rod of the hydraulic cylinder, A indicating the effective acting area of the piston of the hydraulic cylinder, P 1 indicating the oil pressure of an oil inlet cavity of the hydraulic cylinder, P 2 indicating the oil pressure of an oil outlet cavity of the hydraulic cylinder, B indicating the viscous damping coefficient of the hydraulic cylinder, Representing the mechanical unmodeled disturbance of the system, Representing a system state, t representing time; Turning to step 2; Step 2, designing a preset time self-adaptive intelligent controller based on a mathematical model of the hydraulic system: Step 2-1, defining a preset time-varying function for realizing the preset time control of the hydraulic system The method is characterized by comprising the following steps: (8), in the formula (8), the amino acid sequence of the compound, In order to set the time period for the preset time period, 、 Is adjustable positive parameters, wherein the positive parameters Satisfy the following requirements ; Step 2-2, defining a systematic tracking error , wherein, In order to realize the control of the preset time of the hydraulic system, the control input should be designed so that the tracking error of the system converges to an adjustable small neighborhood near 0 within the preset time, and remains within the adjustable small neighborhood range near 0 after the preset time; Step 2-3, defining errors To ensure that An adjustable small neighborhood which is converged to be near 0 in a preset time, and the adjustable small neighborhood which is kept near 0 after the preset time is required to ensure the error Converging to an adjustable small neighborhood near 0 in a preset time, and keeping the adjustable small neighborhood near 0 after the preset time; Step 2-4, defining errors To ensure that An adjustable small neighborhood which is converged to be near 0 in a preset time, and the adjustable small neighborhood which is kept near 0 after the preset time is required to ensure the error Converging to an adjustable small neighborhood near 0 in a preset time, and keeping the adjustable small neighborhood near 0 after the preset time; self-adaptive intelligent controller for preset time of hydraulic system The following are provided: , Wherein the gain is , Is that Is used for the estimation of the (c), Representing the compensation term based on the model, The robust term is represented as such, 、 Are all intermediate variables , Indicating that the tracking error is to be taken, Representing scaled signals ; The specific form of (2) is as follows: , Wherein, the Representing parameter uncertainty items Is used for the estimation of the (c), Representing a known smoothing function; Turning to step 3; And step 3, performing self-adaptive intelligent controller stability demonstration of preset time by using a Lyapunov stability theory to obtain a result of bounded stability of a system tracking error.
  2. 2. The method for adaptively controlling the preset time of the hydraulic system according to claim 1, wherein in step 1, a mathematical model of the hydraulic system is built, specifically as follows: the hydraulic system is applied to linear motion of large-scale industrial heavy-duty mechanical equipment, wherein a load is fixedly connected with a piston rod on a hydraulic cylinder, a hydraulic valve controls the piston rod on the hydraulic cylinder to move, so that the load is driven to move, and a mathematical model of the hydraulic system is deduced according to dynamic characteristics of the load, the hydraulic cylinder and the hydraulic valve; and step 1-2, defining state variables for conveniently designing the controller, and converting the derived mathematical model of the hydraulic system into a state space equation.
  3. 3. The method for adaptively controlling the preset time of the hydraulic system according to claim 2, wherein the hydraulic system is applied to linear motion of large industrial heavy-duty mechanical equipment in step 1-1, wherein a load is fixedly connected with a piston rod on a hydraulic cylinder, a hydraulic valve controls the piston rod on the hydraulic cylinder to move, so that the load is driven to move, and a mathematical model of the hydraulic system is deduced according to dynamic characteristics of the load, the hydraulic cylinder and the hydraulic valve, and the method is as follows: According to Newton's second law, the force balance equation of the hydraulic system is: (1), In the formula (1), m represents the mass of the load, y represents the displacement of the piston rod of the hydraulic cylinder, Indicating the speed of the hydraulic cylinder piston rod, Indicating the acceleration of a piston rod of the hydraulic cylinder, A indicating the effective acting area of the piston of the hydraulic cylinder, P 1 indicating the oil pressure of an oil inlet cavity of the hydraulic cylinder, P 2 indicating the oil pressure of an oil outlet cavity of the hydraulic cylinder, B indicating the viscous damping coefficient of the hydraulic cylinder, Representing the mechanical unmodeled disturbance of the system, Representing a system state, t representing time; then formula (1) is rewritten as: (2), In a hydraulic system, the external leakage of oil in an oil cylinder is ignored, and then the pressure dynamic equation is as follows: (3), In the formula (3), the amino acid sequence of the compound, The effective elastic modulus of the oil liquid is shown, Indicating leakage coefficient in hydraulic cylinder, oil pressure difference between oil inlet and outlet cavities at two sides of oil cylinder Control volume of oil inlet chamber Control volume of oil outlet chamber V 01 denotes an initial volume of the oil inlet chamber, V 02 denotes an initial volume of the oil chamber, Q 1 denotes a flow rate of the oil inlet chamber, Q 2 denotes a flow rate of the oil chamber, Representation of Is a non-modeling disturbance of (1), Representation of Is a non-modeling disturbance of (1), Representation of Is used as a first derivative of (a), Representation of Is the first derivative of (a); Q 1 、Q 2 has the following relation with the valve core displacement x v of the electro-hydraulic proportional servo valve respectively: (4), Wherein the hydraulic valve coefficient , Indicating the flow coefficient of the hydraulic valve, Represents the area gradient of the valve core of the hydraulic valve, Indicating the density of the oil liquid, The pressure of the oil supplied is indicated, The oil return pressure is indicated as the oil return pressure, Representing intermediate variables Is defined as: (5), Neglecting the hydraulic spool dynamics, assuming that the control input u to the spool is proportional to spool displacement x v , i.e., satisfies x v = k i u, where k i represents the voltage-spool displacement gain factor, equation (4) is rewritten as: (6), formula (6), intermediate variable Intermediate variables Intermediate variables 。
  4. 4. The method for adaptively controlling the preset time of the hydraulic system according to claim 3, wherein in step 1-2, for designing the controller, state variables are defined, and the derived mathematical model of the hydraulic system is converted into a state space equation, specifically as follows: Defining a state variable: Wherein the intermediate variable Intermediate variables Intermediate variables Then the equation (2) is converted into a state space equation: (7), (7), Representation of Is used as a first derivative of (a), Representation of Is used as a first derivative of (a), Representation of First derivative of (2), system unknown dynamics , Representing an inherent uncertainty associated with the state of the system, Representing external disturbances related to time, intermediate variables , Intermediate variables Intermediate variables Unknown dynamics of system 。
  5. 5. The method for adaptively controlling the preset time of a hydraulic system according to claim 4, wherein in step 1, in order to facilitate designing the controller, the following assumptions are made: Assume 1 that the system expects the tracking position command x d to be second order continuous and that the system expects the tracking position command and its second derivative to be bounded; suppose 2. Systematic endophytic uncertainty Satisfy the following requirements External disturbance of system And (3) with Satisfy the following requirements 、 Wherein 、 And Are all unknown positive constants; and (2) switching to step 2.
  6. 6. The method for adaptively controlling a preset time of a hydraulic system according to claim 5, wherein in step 2-2, a system tracking error is defined , wherein, In order to realize the preset time control of the hydraulic system, the control input should be designed so that the tracking error of the system converges to an adjustable small neighborhood around 0 within the preset time, and the tracking error is kept within the adjustable small neighborhood around 0 after the preset time, specifically as follows: According to the first equation in equation (7) For tracking error And (5) deriving to obtain: (9), (9), Representation of Is used as a first derivative of (a), Representation of Is provided with a virtual control of the (c), Representation of And (3) with Error of (2); combining the preset time-varying function of (8) to track error Scaling to obtain Scaled signal : (10), Deriving both sides of the formula (10) and applying the formula (9) to obtain: (11), In the above-mentioned method, the step of, Representation of Is used as a first derivative of (a), Representing variables Is used as a first derivative of (a), Is a function of Abbreviations of (a); Selecting Lyapunov function The method can obtain: (12), Wherein, the Representation of Is the first derivative of (a); So that The derivative of (2) is: (13), Designing a virtual control law according to (13) : (14), Gain (14) Then: (15)。
  7. 7. The method for adaptively controlling a preset time of a hydraulic system according to claim 6, wherein in the step 2-3, an error is defined To ensure that An adjustable small neighborhood which is converged to be near 0 in a preset time, and the adjustable small neighborhood which is kept near 0 after the preset time is required to ensure the error The method comprises the steps of converging to an adjustable small neighborhood near 0 in a preset time, and keeping the adjustable small neighborhood near 0 after the preset time, wherein the method comprises the following steps of: according to the second equation in equation (7) For tracking error And (5) deriving to obtain: (16), (16) the process is carried out, Representation of Is used as a first derivative of (a), Representation of Is provided with a virtual control of the (c), Representation of And (3) with Is used for the error of (a), Representation of Is a derivative of (2); combining the preset time-varying function of (8) to track error Scaling to obtain Scaled signal : (17), Deriving both sides of the formula (17) and applying the formula (16) to obtain: (18), In the above-mentioned method, the step of, Representation of Is the first derivative of (a); Selecting Lyapunov function The method can obtain: (19), Wherein, the Representation of Is the first derivative of (a); designing a virtual control law according to (19) : (20), Gain (20) , Is that Is used for the estimation of the (c), Is that Is used for the estimation of the (c), The specific form of (2) is as follows: (21), (21) Representation of Is used for the estimation of the (c), A term of uncertainty of a parameter is represented, Representing a known smoothing function; The parameter adaptation law is designed as: (22), (22), Representation of Is used as a first derivative of (a), In order to adapt the gain of the light source, Is a leakage parameter; The specific form of (2) is as follows: (23), formula (23), Representation of Is used for the estimation of the (c), The weight value of the neural network is represented, Representing the activation function of the neural network, An input representing a neural network; the weighting update law of the neural network is: (24), (24), Representation of Is used as a first derivative of (a), For the weight-adaptive gain, Is a leakage parameter; substituting the formula (20), the formula (21) and the formula (23) into the formula (19) to obtain: (25), (25), Representing the approximation error of the neural network.
  8. 8. The method for adaptively controlling a preset time of a hydraulic system according to claim 7, wherein in the step 2-4, an error is defined To ensure that An adjustable small neighborhood which is converged to be near 0 in a preset time, and the adjustable small neighborhood which is kept near 0 after the preset time is required to ensure the error The method comprises the steps of converging to an adjustable small neighborhood near 0 in a preset time, and keeping the adjustable small neighborhood near 0 after the preset time, wherein the method comprises the following steps of: according to the third equation in equation (7) For tracking error And (5) deriving to obtain: (26), (26), Representation of Is used as a first derivative of (a), Representation of Is the first derivative of (a); combining the preset time-varying function of (8) to track error Scaling to obtain Scaled signal : (27), Deriving both sides of the formula (27) and applying the formula (26) to obtain: (28), In the above-mentioned method, the step of, Representation of Is the first derivative of (a); Selecting Lyapunov function The method can obtain: (29), according to (29), a hydraulic system preset time self-adaptive intelligent controller is designed : (30), Gain (30) , Is that Is used for the estimation of the (c), The specific form of (2) is as follows: (31), (31) Representation of Is used for the estimation of the (c), A term of uncertainty of a parameter is represented, Representing a known smoothing function; The parameter adaptation law is designed as: (32), (32), Representation of Is used as a first derivative of (a), In order to adapt the gain of the light source, Is a leakage parameter; Substituting formulas (30) and (32) into formula (29) to obtain: (33), And (3) switching to step 3.
  9. 9. The method for adaptively controlling the preset time of a hydraulic system according to claim 8, wherein in the step 3, the preset time adaptive intelligent controller stability is checked by using lyapunov stability theory The result of asymptotically stabilizing the tracking error of the system is proved to be as follows: (34)。

Description

Hydraulic system preset time self-adaptive intelligent control method Technical Field The invention relates to the field of hydraulic system control, in particular to a hydraulic system preset time self-adaptive intelligent control method (PTIRC). Background The hydraulic system has the remarkable advantages of extremely high power density, stable output torque, excellent structural rigidity, complete technical system and the like, and is widely deployed in engineering machinery, heavy bearing platforms and various industrial equipment. However, the hydraulic system is essentially a highly nonlinear dynamic system, and the dynamic response during operation is highly susceptible to multiple nonlinear links and uncertainty factors. Specifically, complex flow-pressure coupling relation in the reversing valve, nonlinear friction of an actuating mechanism, volume compressibility of hydraulic medium (oil) and the like form a main nonlinear source of the system, and meanwhile, external environment disturbance and unmodeled dynamics which are difficult to accurately establish introduce significant system uncertainty. As the requirements of modern industrial scenes on the control accuracy and the operation stability of hydraulic actuators are continuously increased, the negative effects caused by the nonlinearity and the uncertainty are more and more remarkable. The control performance of the hydraulic system directly determines the core performance of the high-end equipment, and an advanced servo control algorithm is a key to realizing high-performance servo control. Therefore, aiming at the inherent nonlinearity and uncertainty bottleneck of hydraulic transmission, a novel control algorithm with advancement and strong robustness is developed and introduced, and the novel control algorithm has become a necessary way for breaking through the upper limit of system performance and expanding the high-end application field of the novel control algorithm. In order to overcome the technical barriers of nonlinear control of hydraulic systems, the academia and engineering community has developed and studied various advanced control architectures. The adaptive control theory is superior in coping with unknown system parameters or time-varying problems, and can realize asymptotic tracking of a system steady state, but has the limitation that the adaptive control theory often lacks effective inhibition capability in facing uncertainty nonlinear factors such as external load abrupt change. In view of the fact that practically operating electrohydraulic systems are inevitably accompanied by various kinds of uncertainty nonlinearities, pure adaptive control is difficult to ensure a high-precision control effect in practical engineering. The sliding mode control guides the state variable of the system to reach the preset sliding mode surface in a limited time by constructing a discontinuous switching control law, and the sliding mode control shows extremely strong robustness to the uncertainty of meeting the matching condition. However, the control mechanism generally causes control input discontinuity and jitter problems in a physical system, and the adaptive robust control method can endow the system with definite transient and steady-state performances under the environment that the two non-ideal factors coexist. If high accuracy tracking performance is desired, the feedback gain must be increased. Under the condition that measurement noise objectively exists, the feedback gain which is too large often causes a high-gain feedback effect, so that severe buffeting of control input is caused, and finally, the control quality is deteriorated and even the system is unstable. It is worth noting that most of the existing electro-hydraulic proportional control technologies can only ensure that the tracking error of the system tends to be arbitrarily small when the time is infinite. For practical engineering applications, the response speed is also a key index for evaluating the dynamic tracking characteristics of the controlled system, and to cope with such problems, finite time control techniques are gradually introduced. The finite time control technology can ensure that the tracking error of the system is completely converged in a finite time interval in theory, the convergence efficiency is obviously superior to that of the traditional asymptotic stable control, but the method has the defect that the convergence time is greatly limited by the initial state of the system. Disclosure of Invention The invention aims to provide a hydraulic system preset time self-adaptive intelligent control method, which can realize the bounded stable convergence of transient response and system steady state error of system output in preset time, can definitely establish and be independent of initial state conditions in preset time, and can realize high-precision motion control performance by utilizing a neural network and parameter self-adaptive law