Nonlinear Predictive Control of Active Four-wheel Steering Vehicles

In order to improve the handling stability of active four-wheel steering vehicles, a nonlinear model predictive controller is presented, which can guarantee that the actual sideslip angle and yaw rate can track the ideal sideslip angle and the ideal yaw rate through control of the front and rear wheel angles. A nonlinear static tyre model connected with a linear dynamic model is adopted to describe the vehicle dynamics. Furthermore, the tyre model is replaced by a map in the optimization problem of nonlinear model predictive control. The introduction of maps can reduce the online computational time by a trade-off between the computational burden of CPU and the storage burden of ROM. Simulation results in CarSim indicate that the proposed controller can follow the outputs of the ideal reference model, reduce the computational burden, and improve the handling stability of the active four-wheel steering vehicles effectively.