| 摘要 |
PURPOSE:To prevent unnecessary anti-lock operation, by holding a vehicle speed estimated based on a wheel speed at a constant level under idling condition of wheels, and determining a referential level for judging wheel lock based on said estimated constant vehicle speed during the interval when idling condition continues. CONSTITUTION:Wheel speed of a drive wheel and a driven wheel are integrated in first and second arithmetic units 52, 53 to operate a vehicle speed, then respective estimated speeds are subtracted in a first subtraction circuit 56 while the vehicle speed being estimated from the drive wheel speed and the driven wheel speed is subtracted in a second subtraction circuit 57. Thereafter, a differential output from the first subtraction circuit 56 is compared with a referential level, and if the differential output is larger than the referential level, it is judged that the wheel is idling and a H-signal is outputted from a comparator 58. Consequently, an output from SET output terminal Q of FF65 is brought to H-level which is maintained at a constant level in the first arithmetic unit 52, then the estimated constant vehicle speed is employed as a vehicle speed so as to determine first and second referential levels for judging wheel lock.
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