Robust design of road vehicle suspensions using fuzzy methods

All wheeled vehicles are subject to random excitation by the road or track unevenness. For a dynamical analysis, vehicle models of the vertical vibrations as well as guideway models are required. The fundamental dynamics can already be treated by a one-dimensional suspension model characterized by six design parameters where the shock absorbers are highly uncertain due to wear and poor maintenance. For the assessment of the vehicle performance the main criteria are ride comfort and driving safety depending on the design parameters resulting in a conflict. In this paper, the uncertainties of the parameters are projected into a criteria space featuring a pareto-optimal problem. In addition, fuzzy arithmetic is introduced for the mathematical representation of uncertainties. Simulations of a passenger car that include uncertainties support robust suspension design. It is shown that controlled suspension parameters available now in premium cars remain uncertain due to the unpredictable decisions made by the driver.