The anti-lock braking control proce

The anti-lock braking control process of sudden road conditions during braking will be cleared from high-adhesion coefficient roads to low-adhesion coefficient roads during braking, such as driving into icy roads during asphalt or cement road braking. This anti-lock control process from sudden change of high-adhesion coefficient road surface to low-adhesion coefficient road surface is shown in Figure 4-3. Set at the end of the previous anti-lock braking control cycle. At the beginning of the next cycle, the wheels suddenly go from a high-adhesion-coefficient pavement to a low-adhesion-coefficient pavement, because the brake pressure regulator is still maintained at a level compatible with the high-adhesion cop At higher pressures, there is a possibility that the reference slip rate of the wheels exceeds the threshold S2. Therefore, the angular deceleration at the wheel is less than -a. In the process of changing higher than + a, it is also necessary to judge whether the reference slip rate of the wheel exceeds S2. If the reference slip rate exceeds S2, it means that the wheel is in a state of excessive slip rate. The system will not maintain the brake pressure and continue to reduce the brake pressure until the acceleration of the wheel is higher than the threshold + a (stage 3) . After that, the system enters the brake pressure maintenance stage (stage 4) until the acceleration of the wheels is below the threshold + a again. Then increase the brake pressure at a lower step-up rate (stage 5) until the angular deceleration of the wheel is below the threshold value -a again, and enter the next anti-lock control loop.In the case of low-adhesion-coefficient roads and vehicle speeds below 20km / h, due to the small wheel angle deceleration, the slip rate threshold should be used as the main control threshold, and the wheel angular deceleration and angular acceleration as auxiliary controls Threshold.