Denso Corp developed a pedestrian-car crash detection sensor to be attached to the bumper of a vehicle for the "Pop-up Hood" function.
It was employed for Toyota Motor Corp's Crown Hybrid, whose production began in late January 2013.
The Pop-up Hood is a function that lifts up the hood instantly after the vehicle hits a pedestrian. Because it makes a space between hard parts (such as an engine) and the hood, the impact made on the head of the pedestrian by the hood is reduced.
The newly-developed sensor module consists of a resin hollow structure and two pressure sensors. When the vehicle hits a pedestrian, the pressure inside the hollow structure increases due to the deformation of the bumper. The pressure increase is detected by the pressure sensors, and this information is sent to the ECU (electronic control unit) so that the hood is quickly lifted at certain speeds.
The previous model of the Pop-up Hood detects an impact with acceleration sensors located inside a bumper. But its measurement accuracy needed to be improved because measured value changes depending on the area of the bumper that hits a pedestrian.
This time, there is a hollow structure formed inside and along the bumper. The deformation caused by the crash of the bumper is converted into pressure, and the sensors detect the pressure. As a result, an impact can be accurately measured regardless of the crashed area, Denso said.