Control of a sight system flexible structure: A H∞ design

The basic function of a helicopter-boarded sight system is to stabilize the optonic sensors´ lines of sight. Meeting this functional requirement is increasingly difficult (performance improvement, severe carrier environment, decreasing of size and weight). To solve this problem, the control of sight mechanical flexible structure must be considered. H_∞ design has proved to be successful in dealing with the different structural disturbances and constraints. A novel W4 weight is introduced in the H_∞ standard formulation to ensure the local positivity of the compensated open-loop plant. This property allows the system to be robust against damping variations encountered on flexible structures