Worst-case weakly-dual adaptive control in the frequency domain

In many active vibration or sound control problems there are limitations of applying feed-forward control, the signal of the excitation source is unknown and yet the output variable has to be regulated to zero. If the spectrum of excitation is known the multi-channel approach [20] can be a solution. When the plant transfer function and the amplitude of excitation are both time varying the adaptive control problem becomes increasingly difficult. The present paper provides a solution for slowly time-varying plants. The control scheme introduced maintains worst-case performance via on-line dual-effect of estimation and control.