Baseline vibration attenuation in helicopters: robust MIMO-HHC control

Active control techniques aimed at reducing helicopter vibrations have been extensively studied in the last few decades. The most studied control law is the so-called T matrix algorithm; its implementation requires knowledge of the frequency response relating the control input to the output measurements at the disturbance frequency, which is very hard to characterise analytically. Adaptive schemes have been employed in literature to handle this problem. Surprisingly, however, very little effort has been devoted to the analysis of the T matrix algorithm and in particular to the trade-off between robustness and adaptation in its deployment. In this paper an H∞ approach to the design of a robust T -matrix algorithm is proposed, with the aim of developing a systematic approach to the design of active vibration control laws for helicopters.