Entwicklung mathematischer Software für die Gesamtfahrzeugsimulation

Current numerical methods for simulation and sensitivity analysis in vehicle system dynamics are generally not tailored to the special requirements of the models under consideration. It is thus one aim of this project to identify and classify the structures present in mechatronical vehicle systems and to develop numerical methods which dovetail with these structures. At the same time, the methods must have a user-interface that makes the methods easy to use in every day practice. Such an interface is being developed jointly by the IWR and the Ingenieurbüro Lindner according to the industrial requirements as communicated by the industrial partner BMW. The present paper addresses two points that pertain to efficient simulation and sensitivity analysis. First, the important task of calculating sensitivity matrices in the presence of discontinuities, which are one characteristic of vehicle models, is studied. The technique developed here allows for an error controlled automatic computation of forward sensitivities in contrast to the current practice of cumbersome parameter variation by hand. The every day task of studying the influence of certain parameters on some desired or observed effect is thus simplified significantly. Finally, an inverse-dynamics variant of an Adams-method is described, which speeds up the integration of vehicle models significantly. A numerical experiment with a practical model of a five-link wheel suspension exhibits a speedup of around 50% compared with the standard Adams method and very significant advantages over other integration methods.