An experimental study implementing model reference active structural acoustic control

Model reference active structural acoustic control is experimentally investigated in this study for physical systems characterized by stationary, narrow-band disturbances in which the acoustic field remains relatively unchanged. The filtered-x version of the multichannel adaptive least-mean-square (LMS) algorithm was implemented on a TMS320C25 digital signal processing board to achieve the desired control approach, and control inputs were generated with piezoelectric actuators. Model reference control provides the designer with a method of replacing acoustic error sensors such as microphones located in the far-field with error sensors such as accelerometers located on the surface of the structure. As opposed to driving the response of the structure to zero at the coordinates of the accelerometers, the response is driven to some predetermined ''reference'' value corresponding to the desired far-field acoustic directivity pattern. In essence, the uncontrolled structure is adaptively modified to behave like the reference structure under acoustic control conditions. Results from this study indicate that the same acoustic directivity pattern can be achieved with model reference control, and the only requirement is that the number of structural sensors used in the control approach is at least equal to the number of control actuators required to achieve the desired acoustic directivity pattern.