Pedestrian collision detection sensor. Click to enlarge.

The Pop-up Hood is designed to reduce pedestrian head injuries in a pedestrian/ vehicle engine hood collision by creating a larger buffer space between the hood and hard components, including the engine, under the hood. When a pedestrian collides with the front bumper of a vehicle within a predetermined speed range, the pedestrian collision detection sensor sends the information to the airbag electric control unit to make the hood pop up at the moment of the frontal collision.

The new sensor technology uses a structure that can more accurately detect head-on collisions, regardless of where the collision takes place on the front bumper.

—Hiroyuki Wakabayashi, executive director responsible for DENSO’s Information & Safety Systems Business Group

In the conventional Pop-up Hood, several acceleration sensors are installed along the front bumper. However, detection by acceleration sensors varies depending on which part of the front bumper collides with a pedestrian.

Functioning of the new sensor. Click to enlarge.

DENSO’s new sensor consists of two pressure sensors and a hollow polyethylene housing that is installed across the entire front bumper and conformed to the bumper’s internal shape. In a head-on vehicle/pedestrian collision, these pressure sensors precisely detect the increase in internal pressure of the hollow housing as the bumper deforms, regardless of the collision position on the front bumper.

This sensor is installed on the Pop-up Hood of the Toyota Crown Hybrid launched in Japan.