Multivariable feedback active structural acoustic control using adaptive piezoelectric sensoriactuators. 
An experimental implementation of a multivariable feedback active structural acoustic control system is demonstrated on a piezostructure plate with pinned boundary conditions.  Four adaptive piezoelectric sensoriactuators provide an array of truly colocated actuator/sensor pairs to be used as control transducers.  Radiation filters are developed based on the self- and mutual-radiation efficiencies of the structure and are included into the performance cost of an H2 control law which minimizes total radiated sound power.  In the cost function, control effort is balanced with reductions in radiated sound power.  A similarity transform which produces generalized velocity states that are required as inputs to the radiation filters is presented.  Up to 15 dB of attenuation in radiated sound power was observed at the resonant frequencies of the piezostructure.