LINEAR TIME INVARIANT DISCRETE SYSTEM'S ORDER REDUCTION USING STEP RESPONSE MATCHING TECHNIQUE

Abstract

The analysis and design of higher order systems is quite tedious and costly. It . is therefore desirable that a higher 'order system be replaced by a lower -order system such that the simplified model has enough information to closely : approximate the response of the given system. During the past two decades, various -model reduction techniques, for continuous as well as digital control systems have been developed, in both the time and frequency domain. But simplified methods with' better results are always looked for. The present work is a step in this direction. Here unit step' response matching technique is used to reduce the order of HOS. In this method dominant poles of the HOS is retained in ROS and numerator coefficients are calculated by exactly matching_ the responses of HOS and ROS at some points and at steady state value. Best set of such points is chosen by iteration. But iterations do not last longer as. sufficient small value of ISE is found at some initial points. SISO approach is also extended to MIMO case in this dissertation. (