Collision preventing system for vehicle

Claim 1

A collision preventing system for a vehicle, including a parameter detector for detecting an operational parameter between a vehicle and a contrast obstruction for judging a possibility of collision of the vehicle against the contrast obstruction, one or more brakes being operated on the basis of a detection value detected by the parameter detector, said system comprising: a road surface friction coefficient judgement circuit for judging a friction coefficient of a travel road surface on the basis of a detection value detected by a wheel speed detector which detects a speed of each of a plurality of wheels, and for outputting a judgement signal, when determination is made that the friction coefficient is equal to or less than a predetermined value; a first comparator for comparing the detection value of said parameter detector with a first reference value indicative of a possibility of collision of the vehicle against the contrast obstruction being high, and for outputting, on the basis of the result of such comparison, a first brake control signal indicative of a command to continuously operate each said brake; a second comparator for comparing the detection value of said parameter detector with a second reference value indicative of a possibility of said collision lower than that in the case of the first reference value, and for outputting, on the basis of the result of such second comparison, a second brake control signal indicative of a command to perform a pumping operation for each said brake; and a changing-signal output circuit for outputting a changing-signal indicative of a command to change an operation control mode for each brake in response to the judgement signal outputted from said road surface friction coefficient judgement circuit in a condition in which the second brake control signal is outputted from the second comparator.