Sliding Mode Control For Several Classes Of Uncertain Systems With Time-Delay

Uncertainties and time delays widely exist in various types of real systems, theycan cause system instability and dynamic performance degradation, therefore,designing of strong robustness controllers for uncertain control systems withtime-delays has important theoretical significance and practical value. The idealsliding mode dynamics of sliding mode control (SMC) systems has fully robustness toexternal disturbances and parameter uncertainties which are matched, and the slidingmode dynamic performance can be pre-designed. Due to these good properties, SMCbecomes an effective robust control method for uncertain control systems withtime-delays. Many researchers from different counties have paid attention to thiscontrol approach.The aim of this thesis is to study sliding mode control design approaches foruncertain system with time-delay by combining robust control, adaptive control andsliding mode control theory.The main contents consist of several parts as follows.1. The historical development about SMC and research situation about SMC foruncertain systems with time-delay is reviewed.2. This chapter focuses on robust adaptive sliding mode control for a kind ofdiscrete-time state-delay systems with uncertainties and external disturbances. Thedisturbances and uncertainties are assumed to be norm-bounded but the bound ofdisturbances and uncertainties of state vector is not necessarily known. Thecorresponding adaptive controller is designed to guarantee the trajectory of the systemcan be driven on to the sliding surface in finite time and finally converges into aresidual set of the origin. Also, simulation results are presented to illustrate theeffectiveness of the control strategy.3. The problem of sliding mode control is studied for a class of parabolic uncertain distributed parameter systems with time-delay. Firstly, a sliding modecontroller is designed, and, the approximate time estimate from any initial state tosliding surface is obtained. Secondly, a sufficient condition of asymptotic stabilityfor the sliding motion is derived. Finally, a simulation example is presented toillustrate effectiveness and feasibility of the proposed method.4. The problem of adaptive sliding mode control is considered for a class ofparabolic uncertain distributed parameter systems with time-delay in this section. Theuncertainties and disturbances are assumed to be norm-bounded but the bound ofthem is not necessarily known. An adaptive sliding mode controller is designed toguarantee the trajectory and all signals of the system are uniformly ultimatelybounded. A simulation example is presented to illustrate effectiveness and feasibilityof the proposed method in this paper.