An optimal strategy for differential braking to enhance vehicle stability in severe turning maneuvers

Abstract

In a turning maneuver with high lateral acceleration, the decrease of restoring yaw moment generated by tire lateral force is the basic cause of vehicle unstable motion called spin motion. A practical approach to generate a required external yaw moment, independent of tire lateral forces and steering angle, for recovering the vehicle stability is differential braking. In this paper, a new optimal strategy for differential braking is proposed by considering practical aspects of the problem. To achieve this aim, a control system with two layers is designed. In the upper layer, an optimal yaw moment control law is first developed by using a non-linear 2DOF plane vehicle model. Then, by considering the force capacity of each tire, the calculated external moment is adjusted to an extent that the admissible braking forces are distributed between the left and right wheels of the vehicle in the lower layer. At the end, the simulation studies are carried out to indicate the effectiveness of the proposed strategy to improve the vehicle stability in severe turning maneuvers.