Perturbation rejection control strategy for OWL

The control system of the ESO 100 m telescope (OWL) has to reject slow and fast perturbations in several subsystems. In this paper we focus on the wind rejection control strategies for two subsystems: the main axes and the segmented mirror. It is shown that facing the same disturbance the 2 control designs have to deal with completely different problems: control of a flexible SISO (Single input-Single output) system for the altitude axis versus a dynamically coupled MIMO (Multi input-Multi output) system for the segmented mirror. For both subsystems feasible solutions are given.