Fault Tolerance of the Double Feedback Control System for Minimum Phase Systems

To design a control system with robust stability and low sensitivity, a double feedback control system is proposed. The robust stability condition of the double feedback control system is also obtained. However, if the output from one of the feedback controllers used in the double feedback control system does not work, the structure of the double feedback control system will be changed. This means that the obtained robust stability condition cannot be applied to the double feedback control system for faults of a feedback controller ?In this paper, we examine a design method for the double feedback control system with robust low sensitivity to keep the stability for the plant with varying number of unstable poles on faults of a feedback controller to make the output from one of the feedback controllers constant.