Research On Saturation Control Method For Discrete Switched Systems Based On LMI

Switched systems are an important class of hybrid systems,whose model capability and application range are quite wide.Many control systems such as robot systems and flight control systems can be established to the switched system model for analysis,including continuous switched system model and discrete switched system model.As an important branch of control systems,discrete switched systems have a high research value in theory and practice.Therefore,an increasing number of scholars begin to carry out theoretical research on discrete switched systems,including the stability analysis of discrete switched systems.However,due to the physical constraints of the equipment or artificial constraints,input saturation,state saturation and output saturation frequently occur in the actual control systems,which will cause adverse effects to the dynamic performance and even stability of the system.As a result,the research on control methods of saturated discrete switched systems has essential theoretical significance and great application value.This thesis investigates the discrete switched systems with saturation constraints.The main contents are as follows:(1)The_∞control for discrete switched systems with input saturation,actuator fault and stochastic nonlinearity is studied based on the state-dependent switching method.In order to solve the problem of input saturation and actuator fault,a fault estimator and a low gain fault tolerant controller are designed respectively.The asymmetric input saturation problem is con-sidered and converted to the symmetric input saturation problem.Meanwhile,the sufficient conditions in terms of LMIs for_∞exponential stability of the closed-loop system are provid-ed,and the attraction domain of the system is estimated.(2)The event-triggered_∞control for discrete switched systems with input saturation and state saturation is studied based on the average dwell time method.Applying the convex hull method,a state feedback controller and a dynamic output feedback controller are designed respectively.The dynamic event-triggered strategy is introduced to reduce the update frequency of the controller and save the system resources.Meanwhile,the sufficient conditions in terms of LMIs for_∞exponential stability of the closed-loop system are provided.(3)The finite-time control for discrete asynchronous switched systems with input satura-tion and output saturation is studied based on the mode dependent average dwell time method and the event-triggered strategy.An output feedback controller based on the low gain feedback control is designed for the input saturated system.The output saturation problem is solved by using sector nonlinear condition.The asynchronism of the switched system under the event-triggered strategy which saves the system resources is considered.Meanwhile,the sufficient conditions in terms of LMIs for finite-time stabilization and boundedness of the closed-loop system are provided.