Fuzzy Logic Controllers for Specialty Vehicles Using a Combination of Phase Plane Analysis and Variable Universe Approach

For the control request of specialty vehicles, this paper combines a phase plane analysis with the variable universe fuzzy control technique. Moreover, we develop a new systemic design strategy for the adaptive fuzzy logic controller. With the phase plane analysis, the complete rule base that consists of few key rules can be objectively established, which avoids the irrationality introduced into the process via the subjectivity of the designer of the fuzzy controllers. Furthermore, with the variable universe, the design requirements of the membership functions can be relaxed. Meanwhile, the accuracy of the performance of the fuzzy logic controller can be enhanced despite the limited number of fuzzy rules in the rule base. Based on the Lyapunov stability theory, the stability of the close-loop system can be guaranteed. Simulation results of a double inverted pendulum demonstrate the feasibility of the design strategy for the adaptive fuzzy logic controller, which simplifies the design of the fuzzy logic controller and ensures control. The application of this design strategy can significantly lighten the burden for fuzzy logic controller designers and shorten the development period of the fuzzy logic controller.