H∞ tracking control for a class of uncertain nonlinear systems with time-delay by using multi-model switching
- QIAN Cheng-shan,WU Qing-xian,JIANG Chang-sheng,FANG Wei
J4. 2007, 42(12):
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The design of H∞ tracking control for a class of uncertain nonlinear systems with time-delay was given using multi-model switching in the presence of uncertainty and disturbance. First, T-S models with time-delay were employed to model the uncertain nonlinear system with time-delay. The inputspace was divided into multiple regions. Local T-S models and controllers were designed in each region, such that the approach precision improves as the fuzzy domain decreases under constant fuzzy rules. Then, on the condition that the uncertain is gain bounded, a sufficient condition is presented for the existence of the controller, which satisfies the closedloop stability and the performance of H∞ tracking. By solving a family of linear matrix inequalities, the H∞ tracking control law was obtained. Based on Lyapunov theory, it was proven that the closed-loop system has exponential stability. Finally, a region controller, which was chosen according to the selected variables by the multiple-model switching control, was switched to the whole controller and that other controllers did not operate. The approach and control of the entire nonlinear system was therefore established.