Drifting Planning and Collision Avoidance under Emergency Circumstances

In this article, the drifting's planning and control for the vehicle are studied to solve the problem of emergency obstacle avoidance, which means shorter longitudinal distance than normal lane changing. First, the trajectory optimization problem of obstacle avoidance by drifting is described as an optimal control problem. In the problem, the vehicle and tire models are established under extreme conditions. Besides, the multishooting method is used to take the initial constraint, terminal constraint, control variable constraint, state variable constraint, and actuator constraints into account. Then the drifting planning trajectory obtained after iterative optimization is put into a multi-segment trajectory. Secondly, a three-closed-loop control scheme is designed based on the trajectory tracking error dynamics. Combined with the inversion of the nonlinear vehicle model and the wheel dynamics analysis under saturated conditions, the control actions of the terminal executor are calculated. Finally, the effectiveness of the proposed scheme is verified by simulation. In a double lane change situation, the longitudinal distance is only 9.4m, and the speed is below 5.7m/s.