Hybrid Feedforward/Kalman-Filter Controller for Reaction Force Suppression

Abstract

Abstract This paper presents a method for actively controlling dynamic reaction forces in flexible structures subject to persistent excitations. The motivation is provided by applications in which dynamic loads result in structural or machinery failures (for example, in the bearings of rotating machinery), or in situations where transmitted vibrations degrade the performance of a system or process. This work is a deviation from much of the vibration control work which focuses on suppressing structural displacements instead of forces. The controller is based on an adaptive feedforward disturbance cancellation scheme which has come to be a commonly used method among researchers for persistent disturbance cancellation. In order to use that method for control of forces, however, some modifications are necessary. First, since reaction forces are not typically measured in structures, a Kalman filter state estimator is developed to provide the reaction force signal to the feedforward algorithm, and second, the residual flexibility matrix is used in conjunction with the Kalman filter in order to provide accurate force estimates in spite of a reduced-order model. This paper presents the development of the reaction forces, the Kalman filter estimator, and the hybrid feedforward control law, and applies the overall method to a flexible beam test rig to suppress the dynamic reaction forces at its supports.