Identification and control of split-μ road for antilock braking system

When braking on split-μ road, yaw moment and steering force of vehicle will be produced because the braking force is different for two side wheels. In order to deal with this problem, the modified independent control mode is widely applied, however, there also exits some defects. Because the gap of the adhensive coefficient of both sides is uncertain while braking, if the fixed modified coefficient is applied, it is difficult to keep vehicle direction stability and shorten the braking distance simultaneously under different gap former mentioned. This paper proposes a method named split-μ road identification. Compare the difference of slip integral of front wheels to threshold values during a certain pressure state in order to identify whether the vehicle brakes on split-μ road. According to the integral of slip from both side wheels and vehicle deceleration, the control mode dynamically changes the modified coefficients of pressure. Simulation results show that the algorithm can identify whether the vehicle is braking on split-μ road timely and also can identify the friction difference between the two sides accurately. The pressure regulation mode can regulate brake pressure appropriately and keep vehicle directional stability and shorten braking distance simultaneously.