RELIABLE LINEAR-QUADRATIC STATE-FEEDBACK CONTROL

This paper introduces a procedure for the design of modified linear-quadratic (LQ) state-feedback controls that tolerate actuator outages. The controls improve on the known stability gain-margin properties of the standard LQ regulator by tolerating the insertion of any independent gains from zero to infinity into selected feedback]oops. They also guarantee a given performance bound despite the insertion of gains from zero to two into those loops. The reliable LQ design is shown to be equivalent to a standard LQ-optimal design with a modified performance index. Thus, the design procedure is seen as a means of choosing a particular quadratic performance index for which the optimal control will possess the desired reliability properties.