Lateral stability control on tractor semi-trailer based on anti-jackknife apparatus

On a low coefficient of friction or split-mu road surface, emergency braking may cause semi-trailer to push the tractor from behind until it spins round and faces backwards, and a jackknife accident occurs. To prevent the jackknife of tractor semi-trailer, two main methods can be utilized, i.e. differential braking and anti-jackknife device. The differential braking in emergency braking situations will extend the braking distance and increases the likelihood of accidents. In this paper, an anti-jackknife apparatus was designed and was dedicated to prevent the tractor semi-trailer from jackknife during emergency braking. The articulation between tractor and semi-trailer will be limited by this anti-jackknife apparatus once the anti-jackknife control conditions are met. The control conditions include vehicle speed, steering angle, articulation angle and brake pedal position. Since the articulation angle is difficult to be measured directly, a 3-dof of tractor semi-trailer model was used to design a state observer to estimate it. A virtual prototyping model of tractor semi-trailer was used to simulate the anti-jackknife scenarios in emergency braking situations. The simulation results show that the anti-jackknife apparatus can improve the tractor semi-trailer lateral stability under emergency braking on split-mu road surface at high speed.