Improved μ-synthesis control design for an XY-table

The paper discusses the tracking control of uncertain nonlinear systems. The specific system studied is an XY-table. The control system consists of an “exact” linearizing state feedback and a linear robustifying controller in an outer loop. For the outer loop a controller is synthesized using the μ-methodology. Iterative improvements in the robustness of the controlled system are obtained by stepwise refinements in the structure of the μ-synthesis problem and in the choice of performance weights and uncertainty weights, at the cost of decreased performance. This uncovers the need for preciseness in the choice of design weights