Abstract: A multi-objective hierarchical all-wheel steering control strategy is proposed to enhance maneuverability while reducing tire wear for multi-axle heavy-duty distributed-drive electric vehicles. This strategy comprises three layers: an upper layer, a lower layer, and a coordination layer controller. The upper layer controller preliminarily generates the steering angle for each wheel based on a linear two-degree-of-freedom multi-axle vehicle model that accounts for roll characteristics. The lower layer controller aims to minimize and equalize tire wear by compensating for the steering angles initially calculated by the upper layer. The coordination layer controller employs a Linear Quadratic Optimal controller to cooperatively track the desired vehicle yaw rate and sideslip angle. When the vehicle yaw rate error falls below a preset threshold, tire wear minimization is prioritized; when it exceeds the threshold, vehicle handling stability and safety take precedence. Hardware-in-the-loop tests demonstrate that the proposed control strategy effectively tracks the desired yaw rate and sideslip angle. The vehicle exhibits excellent maneuverability with reduced tire wear under low-speed driving conditions and strong handling stability at high speeds, effectively regulating the sideslip angle within 0.5°±0.3°.

Key words: multi-axle vehicles, all-wheel steering, steering-by-wire, ackermann steering, tire wear, optimal control