Stability Analysis And Control For Switched Systems Based On Constrained Switching Signal Design

Owing to the growing enhancement on complexity and performance demand of modern industry control processes,it is getting much more difficult to satisfy the strict process requirement by traditional single control systems.This problem leads to significant growth of switched systems.A switched system consists of several subsystems(or modes),and a switching signal governing the switching,according to practical demand,among these subsystems.Switched systems can provide a unified framework to model numerous systems and thus can describe complicated control tasks by several subsystems.The convenience has resulted in growing interest towards the research on switched systems.In this dissertation,based on the time-constrained switching scheme,we mainly focus on controllers design and stability analysis problems for several classes of switched systems.Taking the effects,which are caused by frequently encountered factors such as time delay,nonlinearity,unmodeled dynamics,on stability performance into consideration,we propose corresponding cooperative switching and controller design schemes for considered switched systems.The main contributions of this dissertation are summarized as follows:Firstly,the stabilization control is investigated for continuous-time linear switched systems under asynchronous switching.Switching control methods are proposed based on time-constrained switching signals.The effects to the system stability are analyzed with unmatched controllers under asynchronous switching,and the running time criterion is proposed for unstable subsystems and stable subsystems.Based on the linear matrix inequality(LMI)toolbox,the feedback control matrix can be obtained.In addition,the stabilization control is investigated in the presence of neutral time delay.Based on the Lyapunov-Krasovskii functional approach,integral inequalities are utilized in both single and double form to analyze the stability with time-delay.In the controller design procedure,free weighting matrices are introduced,which reduces the complexity of stability analysis significantly.The designed scheme can guarantee the stability of the closed-loop system in the presence of unstable subsystems.Then,the stabilizing problem is considered for a class of discrete-time 2-D switched systems.Unstable subsystems are allowed in the switched system,and the stability condition is derived by restricting the switching numbers and the running time ratio between stable and unstable subsystems.The stabilizing controller gains can be obtained by solving the proposed stabilization results in LMI form.The proposed results can also be extended to the stabilization problem for the 2-D switched systems under asynchronous switching.Finally,the prescribed performance tracking control problem is investigated for nonlinear switched systems in the presence of unmodeled dynamics.The problems caused by unknown nonlinear functions are addressed by adaptive fuzzy logic systems and radial basis function neural networks,respectively.Both average dwell time and a more general stabilizing switching signal are concerned to stabilize the switching systems with adaptive controllers.The proposed scheme relaxes the assumptions that the unmodeled dynamics should be input-to-state stable.The dynamic surface control scheme is incorporated in the controller design procedure,which reduces the complexity of computation significantly.With the aid of prescribed performance control,the tracking performances are guaranteed to satisfied prescribed transient and steady-state requirement,and the fluctuation caused by switching can be constrained as well.