Brake control process on low-adhesi

Brake control process on low-adhesion-coefficient roads When a car brakes on a low-adhesion-coefficient road, the wheels may be locked at a lower pressure, and it takes a longer time for the acceleration to get out of the high slip rate area. Therefore, the anti-lock control of the road with low adhesion coefficient is different from the road with high adhesion coefficient. The control process is shown in Figure 4-2. The first and second phases of the low-adhesion coefficient road surface antilock control are similar to the second and third phases of the high-adhesion coefficient road surface control process. After entering the brake pressure maintenance stage (stage 3), due to the small adhesion coefficient, the acceleration of the wheels is very slow. Within the set brake pressure maintenance time, the wheel acceleration fails to reach the threshold + a, and the ECU determines The wheels are now on a low-adhesion road, and the brake pressure is reduced with a smaller decompression rate until the wheel acceleration exceeds + a. After that, the system enters the brake pressure maintenance stage (stage 4). When the wheel acceleration is lower than + a again, the system increases the brake pressure at a lower step-up rate (stage 5) until the wheel deceleration is lower than the threshold value -a, and enters the next anti-lock control cycle. In the first cycle, the wheel stays at a larger slip rate for a longer period of time. Based on this state information, the ECU uses the continuous decompression method to increase the wheel acceleration to + a in the next cycle (Stage 6). This can shorten the time of the wheel at a high slip rate, and improve the maneuverability and stability of the vehicle.