Lateral stability and constraint boundary of a vehicle with active rear steering

Active rear steering (ARS) can improve the handling stability and maneuverability of intelligent vehicles, but the constraint boundary of the steering angle of the rear wheel is mostly set by using empirical values. Therefore, a nonlinear single-track model of intelligent vehicles with ARS is established. With the help of the linearization of tire mechanics at the point of operation, the handling curve is used to discuss the equilibrium points of vehicles with different axle characteristics, and the dynamic stability of the equilibrium points is studied by using bifurcation theory. On this basis, the global stability of the vehicle under different operating conditions is explored, the constraint condition of the steering angle of the rear wheel is proposed. Moreover, taking the in-phase and anti-phase control methods for the steering angle of the rear wheel as examples, the effectiveness of the constraint boundary of vehicles with different axle characteristics is verified by means of phase portraits. The analytical analysis and numerical verifications both show that the constraint boundary proposed in this paper can provide technical supports for the closed-loop control of the steering angle of the rear wheel, thereby improving the driving stability and safety of intelligent vehicles.