Design of active structural acoustic control systems by eigenproperty assignment

The traditional design approach of feedforward control systems involves the selection of number and location of the actuators and sensors based on some physical understanding of the system. This empirical methodology yields satisfactory results for simple structures and sinusoidal inputs. However, such a heuristic approach can easily result in an inefficient control system with an unnecessarily large number of control channels for complex structures and more realistic disturbances. In this work an efficient formulation is presented for the design of actuators and sensors for structurally radiated sound reduction. The technique is based on the modification of the eigenstructure such that the system responds with the weakest set of modal radiators. The technique is applicable to both narrow-band and broadband excitations. The formulation is demonstrated for controlling the odd–odd modes of a simply supported plate driven by a point force located at the center of the plate. The radiation due to the first three odd–odd modes is reduced with a single-input, single-output (SISO) controller. The control actuator and error sensor are implemented with piezoelectric (PZT) ceramics and polyvinylidene fluoride (PVDF) films, respectively. It is shown that the design approach yields excellent global sound reduction.