In This paper, a method of designing the Controller for large scale uncertain systems. The Controller is
designed via a reduced order model for a given high order system. An optimized reduced order model is
derived with minimum ISE. The proposed method guarantees stability of the reduced model, if the original
high order system is stable system. A PID controller is designed for the high order original systems through
its low order model proposed. This paper presents an improvement to generalized least squares method of
model order reduction. The improvement enhances the flexibility of the method with very little computational
requirement. The reduction procedure is simple, efficient and always generates stable reduced models for the
stable high order systems. The proposed method is illustrated with typical numerical examples taken from
the literature and the results are compared with the other existing methods to show its superiority.