Aizpuru A., Abete J.

Nowadays noise pollution has become an important environmental concern due to uncomforting and health problems it causes. Noise control can promise solutions to this problem, but because of its complexity, it constitutes an important technological challenge. The aim of this work is to reduce the sound radiation of a cantilever beam using a non-collocated “Active Structural Acoustical Control” (ASAC) system. In order to control a mode a single-input single-output (SISO) control strategy has been managed using an “Acceleration Feedback Control” (AFC) with one second-order filter. A piezoceramic stack type actuator was selected and placed on the clamped tip, in parallel to the neutral axis of the controlled beam to induce bending moments. Because of its natural way to measure vibrations, an accelerometer located at the free tip of the beam has been used as an error sensor. Thus, the actuator and sensor pair is non-collocated. This configuration limits the gain of the controller since it produces instability of the non-controlled modes. A new strategy has been developed to stabilize the destabilized modes involving another sensor in a collocated or nearly collocated configuration with the actuator. The design of each compensator has been performed with experimental techniques in order not to appear new resonant peaks. As a result of this work, the experimental noise of the beam has been reduced in the sound spectrum. Also, a new approach has been developed to stabilize the non-collocated SISO actuator/sensor configuration involving another sensor collocated with the actuator. Finally, a stability study of the single-input multiple-output (SIMO) system, with one non-collocated sensor and other collocated with the actuator, has been carried out; both the simulation and the experimental results demonstrate the stability of the controller.