REDUCED ORDER CONTROLLER FOR LINEAR DYNAMIC SYSTEMS

Abstract

For the plant having poor dynamic characteristics such as high overshoot and oscillatory response for step input, a reduced order controller is designed such that the frequency and time responses of controlled system closely matches with those of the reference model. The controller is designed by matching the Pade coefficients and Markov parameters of the transfer function of reference model. The closed loop transfer function of overall system is reduced to a lower order using different techniques of model order reduction (i.e. direct approach) and the unit step responses of the full order closed loop transfer function and reduced order closed loop transfer function are compared with the unit step response of the reference model. The controller is also designed using reduced order model (i.e. indirect approach) and the unit step response of the closed loop transfer function is compared with the unit step response of the reference model. An interactive software is developed in `C++' to implement reduction and overall design procedure. The program has the facilities to design the controller for continuous and discrete time systems. The performance of reduced order models and controller has been tested by comparing the respective step responses using MATLAB