Research On Anti-windup Control Method Of Electro-hydraulic Servo System

Saturation nonlinearity is very common in practical control systems.A large load disturbance or uncertainty in the practical system will easily lead to actuator saturation,resulting in the decrease of system performance or even instability.Electro-hydraulic servo system is widely used because of its rapid response,high power and other advantages,but its typical problem is the actuator saturation.Therefore,the research of input restricted system is very significant.In this paper,a linear model recovery anti-windup controller method of electro-hydraulic system?EHS?is proposed to improve output performance under large load disturbance or uncertainty.Control saturation may occur due to unknown external load disturbance and some hydraulic parameter uncertainties in the EHS model,which will reduce the dynamic performance and stability margin of the EHS.Therefore,the model recovery anti-windup?MRAW?compensator is designed to suppress the actuator saturation.First of all,the existence of nonlinear saturation in the system is ignored,and the unconstrained system controller is designed according to the given performance indicators,and then the deviation of the input signal from the actuator without constraint and with saturation nonlinearity added as input signal to design the anti-windup compensator.The output of the anti-windup compensation is used to adjust the input and output signals of the controller respectively,so as to weaken the influence of saturation on the system performance and make the dynamic response performance of the saturated system recovering the unconstrained response as much as possible.The main work and research results of this paper are as follows:1.First of all,the unconstrained control system and constrained control system are analyzed,including system principle,the actuator saturation and stability issues.Then,the electro-hydraulic servo system is studied and analyzed to establish the mathematical model of the electro-hydraulic servo system;2.Secondly,the basic structure of MRAW is described by block diagram,transfer function and state space.Integrated methods for parameter configuration of LMI-based MRAW compensator that ensures global/local stability and performance is analyzed.Then,an unconstrained system controller is designed.On the basis of this,a system of model recovery anti-windup compensation is designed.Based on the study of the closed-loop stability and anti-windup performance of the saturated system,the state of the anti-windup compensator and the₂L norm of the output of the anti-windup compensator are used as optimization performance indicators,and the stability of the closed-loop system is taken into account.In this way,the anti-windup controller design problem translates into finding the optimal solution based on LMI;3.The designed anti-windup compensator system is compared with other controller systems to verify the effectiveness of the designed anti-windup compensator.The control systems with the unconstrained,constrained and other ordinary anti-windup methods are compared to prove that the proposed method can restore the anti-windup effectiveness.It is verified that the proposed controller can be used to achieve better dynamic performance in the presence of unknown largely load disturbances and model uncertainties.