Integrated Rate And Magnitude Saturation Control For Linear Parameter Varying Systems Via Anti-windup Compensator

Linear parameter varying system(LPV) is commonly found in aerospace, automotive and industrial control field, whose main characteristics concentrate on the time-varying parameters existing in system matrices. According to the time-varying law of parameters, it can be divided into linear variation, periodic variation or random variation. Due to the time varying parameter, the linear parameter varying system is different from the traditional linear time invariant system, so there are great difficulties to the controller design. What’s more, the actuator saturation widely exist in actual control systems. If it is ignored, it will directly impact the system performance. The performance will decline and the system will be instability. Nowadays, most of studies, which talked about saturation, only consider the magnitude saturation of actuator. That is, papers which pay attention to the rate saturation of actuator are little. This paper focuses on the actuator saturation control of LPV systems, where a novel dynamic anti-windup compensator is designed to reduce the negative influence caused by the possible actuator saturation. This article is aiming at reaching the rate and magnitude of the anti windup control strategy in the linear parameter varying system. Different from the most existing results which only concern the actuator saturation on magnitude, this paper takes rate saturation into account, and develops a kind of integrated rate and magnitude saturation control approach, which results that the closed-loop systems can maintain the performance in an acceptable level, even though the actuator rate or/and magnitude saturation occurs. The main research contents can be summarized as follows:(1)The study focuses on the anti-windup method. It is mainly used to realize anti-windup by designing the anti-windup compensator gain. To begin with, the effect of saturation in the system is neglected, that is, we assume that the system does not exist the saturation nonlinearity. According to the performance, the linear system controller is worked well. Then, an anti-windup compensator is designed for reducing the effect of saturation. And the input of the compensator is the difference between the input signal of controller and the output signal of actuator. The study is based on Lyapunov direct method and the linear matrix inequalities.(2)According to the design of the integrated rate and magnitude saturation anti-windup compensator, it is difficult to solve the problem of rate saturation. In the paper, the rate signal is processed to get the generalized amplitude signal, and then the control method is carried out. The input of the anti-windup compensator is the implementation of the mechanism of input and output difference. Considering the system’s nominal controller will maintain a good control effect at the beginnig of saturation nonlinearity happened, we proposed to delay the start of the compensator in order to obtain a better performance. And it solves the set of control problem about the linear parameter-varying systems with the amplitude and rate saturation.(3)In this paper, we seek to provide a systematiccontroller synthesis approach for linear parameter-varying(LPV) systems framework. Different from conventional static anti-windup design approaches, the proposed scheme directly utilizes saturation indicator parameters to schedule accordingly the parameter varying controller. Hence, the synthesis conditions are formulated in terms of linear matrix inequalities(LMIs) that can be solved very effciently.(4)An experiment on an active suspension test system is given finally to illustrate the effectiveness of the proposed approach, and the effectiveness is shown based on the experimental curves and analysis.