Manual control of an intrinsically unstable system and its modeling by fuzzy logic

Abstract The authors have shown in a previous paper that human operators could control stably such an intrinsically unstable object as a double inverted pendulum, when adequate information was given. In this paper, the authors suggest a model of human action in this control system by using fuzzy logic. This model consists of fuzzy and nonfuzzy controllers. The former represents three different modes of control action qualitatively, and the latter switches the control modes according to the situation of the controlled object. The membership functions of the fuzzy controllers are simple piecewise linear functions. Both the membership functions of the fuzzy controllers and the switching conditions of the nonfuzzy controllers are identified experimentally. The control action of this model is very similar to that of a human operator, and the double inverted pendulum can be controlled automatically by this model.