Study on Emergency Obstacle Avoidance Lateral Stability Control of Tractor Semitrailer Vehicles

As a crucial component of highway freight systems, tractor semitrailer vehicles play a key role in the transportation industry. However, their complex vehicle structure can lead to significant lateral instability during emergency obstacle avoidance, posing challenges to the vehicle's dynamic stability and safety. To enhance the emergency obstacle avoidance lateral stability of tractor semitrailer vehicles, a direct yaw moment lateral stability control strategy based on differential driving/braking is proposed. First, a 3-degree-of-freedom ideal linear dynamic model of the tractor semitrailer is established, and the accuracy of this model is validated. Subsequently, an emergency obstacle avoidance lateral stability control strategy for tractor semitrailer vehicles is proposed. The upper-level controller adopts a model-free adaptive control (MFAC) method to track the target yaw rate and vehicle sideslip angle, while the lower-level controller is designed to optimize tire load distribution. Furthermore, to prioritize regenerative braking, a drive/brake torque allocator is introduced. The proposed control strategy is validated under emergency obstacle avoidance conditions. The results show that the designed controller effectively expands the safety boundary for obstacle avoidance of tractor semitrailer vehicles, providing valuable reference for improving the lateral stability during emergency obstacle avoidance.