1. Field of the Invention
This invention relates to a vehicle collision prevention apparatus that activates an automatic brake on the basis of the likelihood of a collision between a host vehicle and a frontward obstruction.
2. Description of the Related Art
An automatic brake apparatus has been put to practical use as a conventional apparatus that both reduces the likelihood of a collision between a host vehicle and a frontward obstruction in front of the host vehicle and reduces damage inflicted during a collision with the frontward obstruction by evaluating the likelihood of a collision between the host vehicle and the frontward obstruction on the basis of output from a distance measurement sensor provided in the vehicle, and executing at least one of outputting a warning to a driver and increasing a brake force as collision prevention processing when the likelihood of a collision is high.
Further, a control device for a brake apparatus that reduces the likelihood of a rear end collision between a host vehicle and a following vehicle by reducing or limiting an increased brake force when the danger of a collision from the rear is detected in a condition where an automatic brake is activated during vehicle travel in order to prevent a collision with a frontward obstruction has been proposed in the prior art (see Japanese Patent Publication No. 4709360, for example).
In a recommended design for the automatic brake apparatus, deceleration is not started until the host vehicle reaches the vicinity of a limit point at which a collision can be prevented, and at the limit point, a brake operation is performed such that a high degree of deceleration is obtained. In so doing, a situation in which the driver of the vehicle becomes overly dependent on the apparatus so as to use the automatic brake habitually can be prevented (see “Technical guidelines for brake apparatuses used to mitigate low speed collisions with frontward obstructions”, Attachment 5-2 of “Technical Guidelines for Automobiles” in Kokujigi No. 44, issued by the Ministry of Land Infrastructure and Transport, Road Transport Bureau, Engineering and Safety Department, May 22, 2009).