Compensation filter for feedback control units with proof-mass electrodynamic actuators

This paper presents studies on velocity feedback control with an electrodynamic proof-mass actuator. It is demonstrated that the stability and performance of the feedback loop could be substantially improved by implementing an appropriate compensation filter. In the simulations the control unit is described in terms of the open and closed-loop base impedance it presents to the structure under control. This allows for a straight-forward physical interpretation of the control system and allows a direct derivation of the expression for the proposed compensator. Studies on the sensitivity of the compensation to uncertainties in the actuator parameters show that even for considerable variations in the actuator response the compensation filter provides significant improvement over the uncompensated case. One draw back of the compensator is the enhancement of the feedback signal at low frequencies. This may lead to stroke/force saturation of the actuator before the optimal control gain can be implemented.