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 its accuracy is validated. Then, a lateral stability control strategy for emergency obstacle avoidance is proposed. The upper-layer controller employs an improved feedforward differential model-free adaptive control (IMFAC) method to track the target yaw rate and vehicle sideslip angle, while the lower-layer controller focuses on optimizing tire load rate. Additionally, a drive/brake torque distributor is introduced to prioritize regenerative braking. The proposed control strategy is validated under simulated DLC conditions representing emergency obstacle avoidance. The results show that the designed controller improves the lateral stability of the tractor-semitrailer by over 30% in DLC scenarios, ensuring accurate trajectory tracking while maintaining low drive wheel tire load rate. This effectively extends the safety margin for tractor-semitrailer obstacle avoidance and provides valuable insights for improving lateral stability during emergency maneuvers.