Abstract: In view of the low accuracy of wheel slip ratio control based on the wheel angle acceleration /deceleration and slip ratio logic threshold control method of antilock brake systen (ABS), as well as based on the fuzzy control method for ABS, a direct fuzzy adaptive control for ABS is put forward. In view of the inaccuracy of the calculated value when the wheel slip ratio tracking error change rate or the wheel angle acceleration /deceleration tracking error is used as the input variable of the conventional fuzzy controller for ABS , a concept and algorithm of equivalent slip ratio change rate of wheel is put forward. By adopting the wheel slip ratio tracking error and equivalent slip ratio change rate as the input variable of ABS fuzzy control system, a conventional ABS fuzzy controller is designed and used as the fuzzy approaching controller of ABS. closed loop control system. By adopting the direct adaptive control method, an ABS fuzzy compensation controller is designed. The two controllers constitute the fuzzy direct adaptive controller of ABS closed loop control system. Simulation and vehicle tests indicate that the controller enhances braking performances of ABS-equipped vehicles, and with simple algorithm, it has practical application value.

Key words: Antilock brake system (ABS), Direct adaptive control, Equivalent slip ratio change state, Fuzzy control