| This thesis investigates the possibility of actively controlling a two-stage vibration isolation mount so as to minimize the transmissibility through the mount. Based on the least-mean-squares (LMS) algorithm, an adaptive control system is developed which performs both system identification and control in real-time. The algorithm is generalized to be applicable for systems with multiple actuators and/or sensors. To demonstrate its performance, the adaptive controller is applied to a two-stage isolation mount to actively control vibration transmission through the mount. Experimental results are presented for both narrowband and broadband excitation signals. To demonstrate the capability of the controller to track changing systems, results are shown for several cases where the parameters of the two-stage isolation mount change in time. It is shown that adaptive control presents an excellent means of achieving optimal control at low frequencies where conventional passive control methods fail.; The issue of stability is investigated for several LMS-based algorithms, and it is demonstrated that narrower stability restrictions occur as a result of the transfer function between the control filter and the error sensor which exists in a physical system. The result is that in order to maintain stability, the algorithms have a smaller maximum convergence parameter of noise or vibration control applications than for corresponding signal processing applications with the same input. |
