Model reference adaptive control of time varying and stochasticsystems

The adaptive control of general delay, linear time-varying systems is addressed. A simple model reference adaptive control law is devised. It does not require a priori knowledge of the sign of the high-frequency gain. This control law coupled with the parameter estimation equations allows a simple representation of the closed-loop system. This greatly eases the stability and performance analysis, and has potential for generalization to adaptive pole placement and other control laws suitable for nonminimum-phase systems. For the Kalman filter parameter estimator coupled with this control law, stability is obtained without persistence of excitation or knowledge of the sign of the high frequency gain. Performance results for the extended-least-squares algorithm are described