Smart panels for active structural acoustic control

This paper presents a theoretical study comparing the sound transmission through different types of smart panels. All of the smart panels considered consist of an aluminium plate of dimensions 247 x 278 x I mm with embedded structural sensors and actuators. The analysis has focused on systems were simple single-channel feedback controllers can be used so that self-contained, compact and light sensor-controller-actuator devices can be built. The panels studied can be classified as being between two limiting cases: first, a panel with a collocated volume velocity sensor and uniform force actuator pair connected via a single channel fixed gain feedback control; second a panel with a 4x4 grid of collocated point velocity sensors and point force actuators each controlled by a decentralised single channel fixed gain feedback control system. For each type of panel the control effectiveness obtained with ideal distributed or local sensor and actuator systems have been contrasted with those of more realistic devices in which the sensing system is made either of a large piezoelectric distributed film or an array of accelerometer point transducers, and the actuation is given either by a large piezoelectric film or an array of small piezoelectric patches. The control effectiveness, stability and robustness of each control configuration have been discussed. Also, some practical problems related to the construction of the smart panels have been briefly described.