ASA 124th Meeting New Orleans 1992 October

4aSA6. A hybrid formulation for blended adaptive feedforward and feedback closed-loop control.

William R. Saunders

Harry H. Robertshaw

Ricardo A. Burdisso

Mech. Eng. Dept., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061

Development and implementation of a novel control algorithm, suitable for active vibration control (AVC) or active structural acoustic control (ASAC), is introduced in this paper. The hybrid algorithm combines the closed-loop properties of the stochastically optimal linear quadratic Gaussian (LQG) design with the robust filtered-X LMS (FXLMS) adaptive algorithm. The resulting compensator provides active damping of plant poles in combination with optimal suppression of persistent disturbances. It is shown that the inclusion of a FXLMS compensator in the forward path leads to more robust harmonic disturbance compensation than is practical for completely feedback-based (e.g., LQG disturbance modeling) techniques. Additionally, the pole-placement properties retained in the hybrid controller provide simultaneous suppression of transient disturbances. The hybrid paradigm uses the Kalman filter estimate of the plant disturbance for the reference signal to the FXLMS block. This nice feature makes the hybrid controller practical for structures where an adequate reference signal is not readily available. Theoretical development of the hybrid controller equations are presented along with a demonstration of a hybrid AVC controller on a simply supported plate. [Work supported by ONR.]