The fuzzy logic control of an active vehicle suspension

Abstract

The object of this research is to design, simulate and test a fuzzy logic controller for an active vehicle suspension. First, the necessary background for fuzzy logic and fuzzy logic control are presented. Next, the background information on a 2 Degree ofFreedom quarter-car suspension model is examined followed by the design ofthe fuzzy logic controller. The simulation is completed by using Matlab, a high-performance numeric computation and visualization software package. For comparison purposes, a passive suspension and a Linear-Quadratic-Gaussian (LQG) controlled suspension are also simulated. The three controllers are subjected to five different analytical road input conditions: step, hump-back bridge, ramp, random linear power spectral density and white noise random. For all five inputs, the LQG and fuzzy logic suspension exhibit superior ride characteristics when compared to the passive suspension. The LQG and fuzzy logic perform similarly when subjected to the first three distinct input conditions. However for the random inputs, the fuzzy logic suspension shows modest improvements over the LQG suspension.