Adaptive H/sub 2/ optimal control based on Smith predictor for continuous-time systems with unknown time delay

In this paper a new adaptive H/sub 2/ optimal controller based on Smith predictor is presented for continuous-time systems with unknown time delay. The proposed controller consists of reference input predictor, H/sub 2/ optimal controller and Smith model predictor. The unknown time-delay and rational transfer function of continuous-time systems can be simultaneously estimated by making use of the modified least-squares algorithm with momentum term. The proposed algorithm is integrated with a new online parameter estimation algorithm to form the adaptive H/sub 2/ optimal controller based on Smith predictor. Simulation results are given to demonstrate the performance of the proposed controller.