TRADE-OFFS IN ROBUST CONTROLLER-DESIGN

In the process of designing robust control systems, the designer often finds that the robust stability and robust performance conditions are not met for the problem as originally posed. Then, it becomes imperative to determine the next step in the control design study so that an effective search is initiated. This can be unequivocally accomplished by a trade-off analysis. Based on the structured singular value paradigm, we present a method that helps the control designer assess the relative importance of information regarding the feedback system. Such information typically consists of process knowledge through the model, control system complexity quantified by the controller order and performance requirements as set forth by the designer. The trade-off analysis is built into the robustness criterion, and simulation examples are utilized to demonstrate the effectiveness of this approach.