Mixed Perturbation Analysis Applied to Life Support Systems Controller Design

In the multiple control input, multiple controlled output system controller design process, it often happens that control providing acceptable performance can be obtained with a more simple control structure than that of full state feedback. The question that is addressed is whether or not one can rationally and quantitatively establish that such a simplification can be validly used in any design situation. This question is highly relevant to the design process because ignoring irrelevant details of a system reduces system development costs. To a large order, the answer to this question has been provided by perturbation theory; both singular perturbation theory and continuous perturbation theory. In this paper we demonstrate how both these means of simplification can be applied simultaneously. An example is presented in which a typical combination of such issues are resolved for a system in which temperature control, differential pressure control, and the opening/closing speed of an airflow by-pass control vane are involved.