Controller reconfiguration based on LTR design

Design of controller reconfiguration (CR) for systems with sensor faults are considered in this paper. One way to accommodate a failing sensor, is by replacing it by an observer based on the remaining outputs. A similar approach can be applied for a faulty actuator by duality. By including observers in the loop to replace faulty components, the nominal feedback controller does not need to be redesigned. The CR observer design problem for the faulty sensors or actuators can be rewritten into a standard loop transfer recovery (LTR) design problem, to which standard LTR design methods can be applied. Finally, it is shown that this CR architecture, where an CR observer is included in the feedback loop in between the system and the nominal controller, can be transformed into a more general fault tolerant controller (FTC) architecture based on the Youla parameterization.