Model-Based Vehicle Trajectory and Its Properties for Automatic Steering Systems

The nonlinear vehicle dynamic model which considers three degrees of freedom of vehicle motion, longitudinal, lateral and yaw was established. For the automatic steering of intelligent vehicles, however, longitudinal dynamic is not taken into consideration, thus, a reduced two DOF model is obtained which regards longitudinal velocity as time variant state of vehicle. According to such a two degrees time variant nonlinear model, a novel model-based vehicle trajectory is proposed. This model considers longitudinal velocity and front wheel steering angle as inputs and vehicle lateral dynamic states (lateral velocity and yaw rate) as outputs. This model is validated using real vehicle testing data. Based on the equations of vehicle model and trajectory, the properties of the vehicle trajectory are analyzed in detail. Finally, the proposed methods and properties are validated through comparison of experiment and simulation studies.