2014 Volume 27 Issue 3 Pages 73-79
In the study of direct design methods using plant transient responses, model matching methods have been proposed. Model matching is useful for the specication of the closed-loop property from the reference input to the plant output, but the main problem is that information about the plant dynamics is necessary to select the reference model and hence the selection often requires trial and error. We have proposed a loop-shaping method that aims at disturbance rejection with a stability margin. The loop-shaping method can be applied to stable plants with less information about the plant dynamics, but it cannot specify the closed-loop property. In this paper, we propose a method of making an appropriate reference model based on the design result of our loop shaping method. In our proposed method, the reference model is a second order system with time delay, and it is selected so that it may have similar properties with respect to the maximum sensitivity and the low sensitivity at low frequencies of the feedback system designed by the loop-shaping method.