| Switched system is a special kind of hybrid system,consisting of a limited number of continuous or discrete subsystems and switching rules that determine how each subsystem operates with each other.The control performance of a switched system is influenced by the performance of each subsystem on the one hand,and the switching signals that control the operation between the subsystems on the other,making the dynamic characteristics of this type of system particularly complex.In engineering practice,many physical systems can be modeled as switched system models,such as power systems,intelligent traffic signal command systems,network control systems,robot control system,etc.Because of its wide existence in real life and engineering applications,the control theory and application research of switched systems has become one of the focuses in the control community.In the actual operation of the physical system,the actual control system will inevitably experience time delay phenomenon due to its own inertia link,response speed and the transmission process of the network signal and other factors.The time delay phenomenon makes the study of the performance analysis and synthesis of the control system more difficult and complex,which will not only affect the dynamic performance of the system,but also reduce the control accuracy of the system,and even cause the system to become unstable.Sliding mode control is a classical nonlinear control method,and its advantages in the control process are reflected in its strong adaptiveness and robustness to uncertain parameters,unmodeled dynamics of the system and external disturbances.In the existing results on stability,observer design and controller synthesis of uncertain time-delay switched systems,it is generally necessary to assume that the time delay information of the system is precisely known in advance.However,due to the complexity of the industrial environment,the state time delay information of the actual control system may not be accurately measured or obtained.Therefore,it is a practical and challenging topic to design an adaptive sliding-mode controller scheme for switched systems where the time delay information is not precisely known,and to further enrich and develop the research on the analysis and synthesis of uncertain time-delay switched systems.In this paper,based on the previous research,the adaptive sliding mode control problem for uncertain switched time-delay systems based on state estimation is further explored,with the following main research contents:1.An adaptive sliding mode control scheme is designed for the uncertain switched system with unknown time-varying delay.Firstly,a new linear sliding mode surface is designed based on a simplified observer that does not require accurate information of time delay to estimate the system state.Next,the exponential stability criterion of the switched system on the designed sliding manifold is given based on the Lyapunov function method,the linear matrix inequality technique and the average dwell time method.To ensure that the system can reach the sliding surface in a finite time,an adaptive sliding controller is synthesized and designed.Finally,simulation comparisons with other literature and chemical reactor system simulations are given to verify the effectiveness of the control strategy in this paper.2.A class of adaptive sliding mode control problems for uncertain switched stochastic systems with unknown time-varying delay is studied.Firstly,a simplified non-fragile observer is designed and a new linear sliding mode surface is constructed based on the observer.Based on stochastic stability theory,linear matrix inequality technique and average dwell time method,the exponential stability of the system in the sliding phase is guaranteed.Then,an adaptive sliding mode controller is designed to ensure that the system trajectory moves to the designed sliding mode surface within the finite time.Finally,the effectiveness of the control strategy is verified by simulation cases. |
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