Active structural acoustic control smart panel with small scale proof mass actuators
This thesis presents a comprehensive study of decentralised feedback control on a smart panel with electrodynamic proof mass actuators and velocity sensors at their footprints. The aim is to provide guidance for the design of light, simple, robust and low cost, control units which can be attached in large numbers to flexible structures in order to control their spatially averaged response and sound radiation at low audio frequencies. The first part of the thesis is focused on the identification of simple and effective single channel feedback control laws. In particular the stability properties and control performance produced by Proportional, Integral, Derivative, PI, PD, PID feedback control laws are assessed with reference to two simple problems where a single degrees of freedom system is controlled by an ideal reactive force actuator and by a practical proof mass actuator. Following this introductory study, the implementation of decentralised feedback control on a smart panel with five control units using proof mass electrodynamic actuators is investigated for the best two cases of Proportional and PID control. In parallel the practical design of small scale control units is explored. In particular the scaling of the stability and control performance properties of a single control unit that implements proportional control is examined using a stability control formula. The final part of the thesis presents the stability and control performance tests carried out on a single control unit and on five decentralised control units. For the multiple channel control case, the reductions of the spatially averaged vibration measured with a laser vibrometer and the reduction of the total sound power radiation measured in an anechoic room are presented.