A mixed method for the reduction of multivariable discrete systems

Many real, physical control systems can only be described by high order, large dimensional, discrete multi input-output transfer function matrices. The analysis and synthesis of such large systems are a computationally difficult task. Several methods are available for obtaining a lower order model. The available methods that provide the reduced model are suffered by either difficulties in computation, or stability problems. In this research the mixed method which uses the dominant-eigenvalue concept and the continued fraction approach is used in the z-domain to simplify z-domain- transfer-function matrices with various dimensions. The reduced model is simple and always stable and the dominant performance of the original system is retained.