SUMMARYThe issue of observer-based tracking control for switched linear systems with time-varying delay is investigated in this paper. The possibility of designing switching control laws based on measured output is considered when the states are not available. Hysteresis based switching method and single LyapunovKrasovskii functional method are utilized to the stability analysis and controller design. By introducing the descriptor system method, the consideration of mixed mode is avoided sinceẋ(t) can be seen as state variable, and thus it is not necessary to substituteẋ(t) everywhere by the right-hand part of the system. The variation-of-constants formula is used to overcome the difficulties caused by the estimation error and exotic disturbance. Free weighting matrix scheme facilitates us to the stability analysis and control synthesis, and the numerical example shows the effectiveness of the proposed design methods.

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Tracking control for switched linear systems with time‐delay is investigated in this paper. Based on the state‐dependent switching method, sufficient conditions for the solvability of the tracking control problem are given. We use single Lyapunov function technique and a typical hysteresis switching law to design a tracking control law such that the H∞ model reference tracking performance is satisfied. The controller design problem can be solved efficiently by using linear matrices inequalities. Since convex combination techniques are used to derive the delay independent criteria, some subsystems are allowed to be unstable. It is highly desirable that a non‐switched time‐delay system can not earn such property. Simulation example shows the feasibility and validity of the switching control law. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society