A Nonlinear 5-Degrees-of-Freedom Model for Tractor Semi-Trailers

The complexity and accuracy of a vehicle model depends on the purpose of the modeling. A nonlinear 5-degree-of-freedom (5-DOF) tractor semi-trailer model is proposed in this paper for bifurcation analysis of the vehicle system dynamics. Both yaw and roll motions are accounted for in the model. A nonlinear tyre model is adopted for capturing the nonlinear behavior of the system. Lateral load transfer of wheels due to lateral acceleration and roll of sprung masses and hysteresis behavior of suspensions are also considered to improve model accuracy. Parameters of the 5-DOF model are extracted from a TruckSim model. Comparison between the responses of the two models shows that the proposed nonlinear 5-DOF model has a high accuracy and as such, is believed to be capable for design of vehicle state/parameter estimators or active chassis controllers.