AbstractRobust, i.e. structurally stable modelling of the motion of articulated vehicles is important in order to get all qualitatively possible ways of behavior. For the example of a tractor- semitrailer vehicle it is shown, that in a two parameter family (driving speed V and the loading condition expressed by the location d of the masscenter of the trailer) only three classes of qualitatively different ways of behavior are possible. These cases are analysed by perturbing them in the most general way possible by means of imperfection parameters, to obtain a robust model. The mathematical methods are supplied by Bifurcation Theory.