Development of future pedestrian protection technologies.

Because many pedestrians suffer fatal head injuries in traffic accidents in Japan, methods of evaluating pedestrian head protection are being investigated along with various technologies for improving the energy-absorbing characteristics of the vehicle body. One approach to improve energy-absorption is to expand available energy-absorbing space. However, this approach has a considerable influence on vehicle design, which is directly related to fuel economy. Accordingly, future technologies for increasing energy-absorbing space through the use of devices or for reducing the head impact velocity itself are also considered important. This paper describes two future pedestrian protection technologies that have less effect on vehicle design. One is a "rear-rising hood" that increases the energy-absorbing space at the time of a vehicle-pedestrian collision. The other is an "airbag system for controlling pedestrian collision kinematics" that can help reduce the head impact velocity against the vehicle by helping to control the kinematics of a pedestrian following a collision with a vehicle. The "rear-rising hood" is designed to raise the rear part of the hood upon estimating or detecting an imminent collision between a pedestrian's head and the vehicle. It uses an electric motor to drive an actuator that raises the rear part of the hood by 100 mm and can also lower the hood again. In collision tests conducted with a pedestrian dummy and an experimental vehicle fitted with the system, it was found that head injury values were reduced by 50% under certain controlled conditions. The "airbag system for controlling pedestrian collision kinematics" features an airbag mounted at the front of the vehicle to control the collision kinematics of a pedestrian. This system can help serve to control the collision kinematics of a pedestrian's lumbar region such that it moves upward over the hood leading edge instead of rotating around the hood edge. In collision stead tests conducted with an experimental vehicle fitted with this system, it was found that the impact velocity of the pedestrian dummy's head against the vehicle was reduced by 50% under certain controlled conditions. For the covering abstract see ITRD E825082.