Switching of H∞ controller under existence of constraints on state variables

In real control systems, there are some constraints on the value of inputs, states and outputs. If such constraints are violated, systems may become unstable as the worst case scenario. One of the promising approaches to solve this problem is to switch the controller according to the state of the closed loop system. No useful design strategy for each controller, however, has been developed yet. In addition, the decision of controller state at the instance of controller switching has not been investigated. First of all, this paper presents a new design methodology which merges the switching control and H_∞ controller design into one design algorithm. Secondly, this paper presents a way to decide the controller states at the instance of controller switching. Finally, the proposed method is applied to a force control of one DOF manipulator to demonstrate the usefulness of the proposed method