LAUSR

In order to avoid collisions in emergency conditions, the autonomous vehicle may be necessitated to maneuvers up to their handling limits. In these scenarios, the vehicle must be able to react quickly although the longitudinal and lateral coupled and nonlinear dynamics are significantly enhanced. To improve the accuracy of trajectory tracking and vehicle stability at the handling limits, this paper presents a hierarchical motion control framework that prioritizing lateral response. For lateral motion control, a nested architecture that consists of lateral deviation control and yaw rate control is designed considering parameter uncertainties. In longitudinal motion controller, the constraints of longitudinal tire forces are calculated on the premise of meeting steering demand. On this basis, an active load transfer strategy is proposed to optimize the steering response, which increasing the lateral stiffness of the front wheels through load transfer generated by active braking. Meanwhile, a longitudinal speed control algorithm considering the longitudinal acceleration demand is developed based on conditional integral method, to cope with the contradiction between fast tracking and small overshoot. Finally, experimental results in different scenarios demonstrate that the autonomous vehicle with the proposed control scheme can track the desired trajectory stably and accurately at the handling limits.