A Fuzzy Controller for Automotive Active Suspension Systems

This paper presents a new efficient method for controlling active suspension systems. The approach uses a fuzzy scheme which offers new opportunities in the improvement of vehicle ride performance. The scheme handles uncertainties of the problem, and tunes the controller to treat the conflict requirements of ride comfort and road holding parameters within a specified amount of the suspension deflection. The two degree of freedom quarter car model is used to evaluate the performance parameters when the vehicle is subjected to a random road input. Based on this description of road profiles, theoretical techniques necessary to implement the control strategy are introduced for the first time in the literature. Results of an active suspension system based on linear quadratic regulator (LQR) optimal control theory are also generated, so they can be used as a guide in scaling the performance of active systems with fuzzy control.

Results indicate that the fuzzy logic control system improves both the ride comfort and road holding parameters in comparison with the LQR active suspension system. These improvements are shown as a reduction in root mean square (rms) values of the body acceleration and dynamic tyre load by 16% and 18% respectively without any increase in the rms value of the suspension working space.