Multichannel Adaptive Vibration Control of a Mounted Plate

This thesis investigates the possibility of actively controlling a plate, mounted to a rigid foundation with springs. A multichannel adaptive control system, based on the least-mean-squares LMS algorithm, has been developed and applied to the transmission paths of this mechanical plate system. Experimental results are presented for the case of single and multiple-frequency excitation. Feedback compensation is developed to remove any feedback in the control system, and thus avoid any instabilities caused by such feedback. The effect of this control on vibrating modal patterns is presented and thus gives insight to global as well as to localized effects of active control. It is shown that this multichannel adaptive control system presents an excellent means of controlling low frequency vibration transmission where passive techniques fail. The issue of stability of a coupled system, such as a plate, is addressed and a solution is presented. In addition, stability and convergence properties of multiadaptive processes are presented. The result is that convergence parameters of each separate adaptive process have to be carefully selected, with respect to other convergence parameters, in order to avoid system instabilities.