Adaptive vibration control of smart structures: a comparative study

Fixed gain controllers, designed for a nominal system, degrade in performance when the system parameters are perturbed. By making the controller adaptive, ideal performance and granted stability of the closed loop system can be achieved for even a large change in system parameters. In the present study, adaptive controllers based on minimum variance, pole placement and linear quadratic techniques are investigated. The controller based on minimum variance is noise sensitive and the actuator voltage changes sign after each sampling interval. Hence, it is detrimental to the life of piezoelectric actuators. An adaptive controller based on the pole placement technique requires high control effort and gives poor performance at and near the nominal system. But linear quadratic control based adaptive controllers are noise tolerant and are free from the above-mentioned limitations.