Development of Pre-crash Safety System with Pedestrian Collision Avoidance Assist

A new pre-crash safety (PCS) system with pedestrian collision avoidance assist has been developed. This system is capable of detecting both vehicles and pedestrians, and helps the driver to avoid a collision by automatically braking the vehicle by up to 40 km/h, one of the highest rates of deceleration for a PCS system in the world. Pedestrian detection is enabled by a sensing system that combines millimeter wave radar and a stereo camera. This system is capable of stable object detection regardless of day or night. At night, the system uses near infrared projectors to enhance the detection performance of the camera. This paper describes the core technology for achieving this system, including brake control technology for decelerating the vehicle by up to 40 km/h to help avoid a collision, and recognition technology capable of detecting pedestrians walking quickly across a road. The collision avoidance brake control technology achieves higher and more accurate deceleration than conventional systems, and is robust against variations in brake effectiveness. These variations are suppressed by the control algorithm, which uses the distance to the object and the deceleration as feedback parameters. As a result, the target deceleration performance may be achieved even under certain conditions of brake effectiveness variation. In addition, the timing of braking start was designed not to interfere with collision avoidance operations performed by the driver. The deceleration and jerk (i.e., the deceleration gradient) were also determined considering the risk of the driver becoming dependent on or over-confident in the system. An effective recognition technology that helps to prevent a wider range of accidents should be capable of detecting pedestrians quickly crossing a road. To further this goal, the response of the position detection filter of the millimeter wave radar was enhanced, and new algorithms were developed for collision judgment as well as the fusion between the millimeter wave radar and stereo camera. These measures enable highly accurate collision judgment for pedestrians crossing a road.