Bumper contact sensor for pedestrian collisions based on analysis of pedestrian kinematic behaviour

Abstract

An active bonnet and pedestrian airbag are effective in providing a high level of pedestrian head protection. For triggering the activation of these systems, a reliable sensor that distinguishes a pedestrian collision from collisions against other colliding objects is necessary. In this research, a pedestrian contact sensor based on the pressure of a deformable chamber was investigated from finite-element (FE) analysis. In a simulation of a component test of a chamber impact, the internal pressure of the chamber increased with the volume deformation of the chamber according to Boyle's law. The chamber was installed above the top plane of the bumper energy absorber of a simple car model, and FE simulations of a car–pedestrian collision were conducted. The chamber deformed and its internal pressure increased as the bumper energy absorber deformed during contact with the pedestrian leg. It was shown that the pressure response of the chamber could be detected, irrespective of vehicle shape and structure. This particular pressure response in pedestrian collisions was different from that in collisions into other objects such as a road pole. The contact force of the bumper energy absorber tends to be linear with the pressure change of the chamber. It was shown that a pedestrian collision can be distinguished with high reliability from other colliding objects using the chamber pressure based on the colliding characteristics depending on each colliding object.

Keywords:

• pedestrian protection
• contact sensor
• human finite-element model
• road pole