Abstract
The sensitivity reduction of the optimal control system is discussed. An optimal system is constructed to have two degrees of freedom by using the output feedback and the prefilter. This implementation enables us to reduce system sensitivity without disturbing the optimality. This is a main advantage of the proposed method.
The synthesis procedure is as follows:
i) Using a suitable algorithm, the optimal problem is solved to find an open-loop type solution.
ii) The feedback compensator element which needs only output signals of the plant is designed to minimize a given sensitivity performance index.
iii) The prefilter is determined so that the total input to plant, that is, the output signal of the prefilter plus the feedback signal, coincides with the open-loop input.
The resultant system is called an optimal feedback system.
Several examples are given to illustrate the synthesis procedure.
