Abstract: For the problem of insufficient use of the ground adhesion coefficient and high nonlinearity of the Anti-lock Braking System (ABS) in the process of automobile braking,a road surface recognition algorithm is designed based on Burckhardt's tyre model,and the optimal slip rate detected by the road surface recognition algorithm is fed into the fuzzy variable structure control,so as to propose a fuzzy variable structure control strategy for ABS based on road surface detection.The results of the simulation experiments show that the road surface recognition algorithm has  fast response and high accuracy;under the conditions of variational road surface,the fuzzy variable structure control reduces the braking time by 7% and the braking distance by 6% compared with the variable structure control,and the amplitude of the jitter vibration of the controller output is effectively attenuated.

Key words: anti-lock brake system, road surface recognition, fuzzy variable structure control, optimal slip ratio