Collision avoidance apparatus

A collision avoidance apparatus for a vehicle, the apparatus comprising:

• an obstacle detection unit that includes a first sensor to detect an obstacle positioned ahead of the vehicle;
• an approaching object detection unit that includes a second sensor to detect an approaching object approaching the vehicle from behind the vehicle;
• and
• an electronic control unit configured to:
• (i) calculate a collision time until the vehicle collides with the obstacle detected by the first sensor, based on a distance between the vehicle and the obstacle, and a relative speed of the obstacle with respect to the vehicle;
• and
• (ii) execute a drive support to avoid the collision between the vehicle and the obstacle based on the collision time, and to start the drive support when (1) a vehicle speed of the vehicle is greater than or equal to a predetermined lower limit speed and (2) the collision time is less than or equal to a predetermined threshold;
• wherein the electronic control unit executes at least one of
• (a) lowering the lower limit speed when it has been determined, based on an output of the second sensor, that a likelihood exists for the approaching object to collide with the vehicle from behind the vehicle, and
• (b) starting the drive support when it has been determined that the likelihood exists for the approaching object to collide with the vehicle from behind the vehicle, and the collision time is less than or equal to the predetermined threshold, even when the vehicle speed of the vehicle less than the predetermined lower limit speed.