Compatible suboptimal controllers for fixed linear plants

Many optimal control problems generally lead to solutions that require complete state feedback for their implementation. For many practical applications, however, not all states are available for direct measurement. The use of an auxiliary dynamic feedback system, such as an observer, is one approach to the design of a controller that generates an asymptotic estimate of the desired optimal control input. However, a simpler design is desirable and is often possible by means of the theory of compatible suboptimal controllers presented in this paper.