Controller reduction using normal coordinates of reconstruction error matrix and component cost analysis method

The elements of the component cost analysis method (CCA) were developed. The method is based on the decomposition of the quadratic performance index of the plant-controller system into components that indicate the contributions of the different controller states to its optimal value. This method enables the order reduction of linear quadratic Gaussian (LQG) designed controllers, with negligible effects on the closed-loop performance. The method also ensures that the optimal reconstructed errors of the important feedback states are totally unaffected by the reduction of the order of the observer.