Abstract
Abstract-Optimal control deals with the problem of finding a control law for a given completely state controllable system such that a certain optimality criterion (performance index) and best possible behavior with respect to the this criterions achieved. If some states are not accessible for feedback, a state estimator to estimate these states can be used. If the system is nonlinear system, the conventional controller cannot predict the systems behaviors with acceptable accuracy. In this paper a different modified estimator’s based controller are presented. A modified controllers such as Optimal estimator based on linear quadratic regulator with integral control (OELQRIC) is designed in this work. This controller will make linearized system operates as model reference for nonlinear systems. The obtained results are remarkably acceptable.