Abstract: An instantaneous revolution speed Nm of an input shaft is calculated from an input period of a pulse signal from a revolution sensor, a revolution speed Nf is calculated by filter processing the instantaneous revolution speed Nm, a determination is made that a belt slip occurs when, during a stop of a vehicle, a state in which the revolution speed Nf is equal to or higher than a slip determination speed NSL is continued for a time equal to or longer than slip determination time TSL, and an immediately prior revolution speed Nf is held until a time of a pulse signal no input exceeds a road wheel lock corresponding time TWL which is longer than a slip determination time TSL.

Abstract: An instantaneous revolution speed Nm of an input shaft is calculated from an input period of a pulse signal from a revolution sensor, a revolution speed Nf is calculated by filter processing the instantaneous revolution speed Nm, a determination is made that a belt slip occurs when, during a stop of a vehicle, a state in which the revolution speed Nf is equal to or higher than a slip determination speed NSL is continued for a time equal to or longer than slip determination time TSL, and an immediately prior revolution speed Nf is held until a time of a pulse signal no input exceeds a road wheel lock corresponding time TWL which is longer than a slip determination time TSL.