Adaptive feedback technique for unmodeled disturbance rejection

Abstract

This work presents experimental results of a hybrid control technique that blends traditional fixed feedback control with adaptive feedback techniques. The objective is to provide damping for transient disturbances via the fixed controller and rejection of steady disturbances via the adaptive controller. This technique differs from other control techniques in that it does not require a measurement of an external signal coherent with the disturbance, nor does it require knowledge of how the disturbance enters the system. As with all feedback techniques, stability is an issue. The adaptive controller is implemented to minimize stability problems and in the case of perfect system identification, it is guaranteed stability. The experimental results are from a cantilever beam with piezoceramic actuators and sensors. The fixed feedback controller results are compared to the adaptive feedback control results. The comparison will include results from disturbances resulting from a single harmonic, narrowband signal, and broadband signal.