Structure Selecting and Design Method for Control Systems Considering Plant’s Order Change

In model-based control system design, redesign is required when the order of the plant model changes. It inhibits prospective design in the control system design procedure, consisting of “plant modeling” and “controller design.” Moreover, the problem of control structure often depends on experience and knowledge, and emphasis is more placed on how to determine the optimal parameters after the control structure is determined than on other crucial elements. This paper proposes methods based on the partial model matching method that does not require controller redesign when the order of the plant changes and for selecting the control structure by comparing the characteristics of several approaches, including the change of plant order, not taken into consideration so far in the literature. The proposed method can stabilize the plant by designing the controller for higher-order plants and adjusting its coefficients for order-changed lower-order plants.