Flight control synthesis using robust output observers

A brief investigation was made of the application of robust output observer theory to the design of flight control systems for advanced aircraft configurations. Observer theory constitutes a natural design tool because the resulting observers are in themselves unobservable and do not increase the order of the closed-loop response, thereby more closely satisfying flying qualities requirements. Examples are presented to show that the observer configuration is not unique in either the observer poles or the output sensors, and many different control system configurations using a variety of sensors can be designed to yield identical closedloop dynamic behavior. In this way, considerable analytic and physical redundancy can be incorporated into nearly any flight control system.