An Antirollover Control Strategy Based on Time-Varying Nonlinear MPC for Three-Axle Steering/Braking-by-Wire Vehicle

Under extreme working conditions, three-axle vehicle is accompanied with a huge load transfer ratio, and there is a large risk of sideslip or rollover, where the unnecessary intervention of antirollover control may worsen vehicle's unstability. In order to improve the vehicle antirollover performance and stability, a steering/braking-by-wire-integrated antirollover control strategy is proposed. The strategy mainly consists of a mode selection layer and an integrated control layer. In the mode selection layer, a multiple coupled degrees of freedom energy method combined with a nonlinear vehicle prediction model is designed to accurately evaluate rollover risk, and determine the control mode. In the integrated control layer, a novel time-varying nonlinear model prediction control is adopted to solve the desired tire forces and front wheel steering angle to inhibit load transfer and prevent rollover. Besides, the actuator constraints changing with the tires' vertical forces dynamically are considered. The proposed strategy is evaluated with a Trucksim-MATLAB simulation and hardware-in-the-loop experiment. The results show that the proposed strategy can accurately assess the rollover risk and improve the yaw stability and antirollover performance significantly.