An Approach for Including Reliability in Control System Designs

An approach is developed for non-catastrophic control component failure accommodation for large space structures. Reliability is considered for both the control configuration (i.e., selecting actuator locations over an admissible set) and the ultimate operation of the system. The approach presented is to construct a measure of performance that indicates the absolute goal of the system, and for a given structural design, to determine the lowest achievable cost conditional upon the failure states of the system (i.e., which actuators are operational). These costs are then weighted and summed to provide an overall system performance measure. This expected performance measure is then minimized over the set of admissible control configurations. A complete mathematical development is presented for a flexible beam and a grid structure. The optimal configurations for the failure states are determined for different normalized time of mission. Although the research is concerned with a particular problem, the analysis of the reliability incorporation in the design of control systems is of more general interest.