A hybrid structural control approach for narrow-band and impulsive disturbance rejection

A hybrid structural control architecture which combines feedback-based transient suppression and robust narrow-band disturbance compensation using adaptive filtering methods is introduced in this paper, A general formulation of the controller is introduced first, without regard to specific feedback or adaptive feedforward algorithms, It is shown that inclusion of a feedback loop around an adaptive feedforward path leads to faster convergence times of the adaptive compensator, The improved convergence characteristics are shown to be quite important to the performance of the adaptive control in the presence of impulsive disturbances. An important contribution of the proposed hybrid controller is the generation of an uncontrollable reference signal for the adaptive filter via an estimate of the disturbance(s) from a Kalman filter, Analysis of the hybrid compensator demonstrates that the new control law functions as an adaptive feedback controller when the estimated disturbance is used for the reference signal, Demonstrations of the hybrid control system are presented for a simply supported plate subject to a mixed transient and persistent, narrow-band disturbance, Numerical and experimental results are based on implementation of a discrete linear quadratic Gaussian regulator design for the feedback loop and the filtered-X least-mean-squares adaptive feedforward algorithm, The simulation and test results confirm improved convergence properties, stability, and performance robustness of disturbance compensation and reduced sensitivity of the adaptive filter to transient disturbances for the hybrid implementation, The hybrid design has potential in improving active control effectiveness in industrial noise and vibration control problems characterized by mixed impulsive and persistent disturbances. (C) 1996 Institute of Noise Control Engineering.