Over the past few years, the demands on future vehicle generations concerning pedestrian protection improvement have been discussed especially in various European and Japanese automobile committees, consumer protection organizations and by legislation. These discussions led to, amongst other activities, government regulations for Europe and Japan, which prescribe various testing which verifies pedestrian protection. In order to fulfill the prescribed head impact tests, a certain stiffness characteristic of the bonnet is necessary, which can be achieved besides passive means with an active bonnet lifting device. They consist of a sensor system, which detects the pedestrian impact, and an actuator system, which lifts the bonnet.

In this article, the main focus will be on the development of a sensor system including the discussion of requirements arising from legislative specifications and OEM market trends. Furthermore, typical test and simulation procedures are presented which provide the input for algorithm development. A central point regarding algorithm performance is the capability of pedestrian detection, especially under consideration of different temperatures, mounting and production tolerances and an inhomogeneous front end stiffness distribution. The differentiation of pedestrian collisions from misuse objects (e.g., stone- and bird-impact, parking dent) is also an important aspect, because a high misuse activation rate has a negative influence on customer satisfaction. This item will be also discussed.