Industrial application of an H∞ design method for flexible structures

This paper presents an industrial application developed by Sfim Industries Ets d´Asnieres to a helicopter sight system stabilization. The H∞ synthesis of robust controller for flexible structures is presented. Penalizing the closed loop regulation function G(1+KG)^-1 allows one to avoid pole cancellations and to damp some flexible modes without increasing the regulator order. This approach is reminiscent of the idea of positivity. The stability margin is ensured by the H∞ standard W3 weighting function which also handles the roll-off behaviour. Experimental results obtained show the efficiency of this approach in the case of sight system flexible structure in comparison with classical PID based regulation