Improvement of pedestrian safety: response of detection systems to real accident scenarios

Abstract

The scope of this research concerns pedestrian active safety. Several primary safety systems have been developed for vehicles in order to detect a pedestrian and to avoid an impact. These systems analyse the forward path of the vehicle through the processing of images from sensors. If a pedestrian is identified on the vehicle trajectory, these systems employ emergency braking and some systems may potentially employ emergency steering. Methods for assessing the effectiveness of these systems have been developed. But, it appears difficult to determine the relevance of these systems in terms of pedestrian protection. The general objective of this research was to test the response of these systems in many accident configurations. The first step consisted of gathering a sample of a hundred of accidents involving vehicles with pedestrians. These accidents were provided from accident databases of two laboratories LMA and CASR. Data of these accidents were recorded in sufficient detail from in-depth investigation which enables reconstructing the trajectory of the vehicle and pedestrian prior to the collision. The second step was to analyse qualitatively and quantitatively the data of the selected accidents. These accidents were reconstructed to simulate the pre-crash conditions. From this accident reconstruction, factors relevant to the primary safety of pedestrians were deduced. The next step consisted of coupling the vehicle dynamic behaviour with a primary safety system in order to confront these systems to real accident configurations. The potential of these systems is studied by verifying the feasibility of deploying an autonomous emergency manoeuvre during the timeline of the accident and according to the vehicle dynamic capabilities: i.e. verifying the possibilities in terms of crash avoidance. Based on this procedure, three modelling methods were developed: a first method testing a system to each accident configuration and two others using graphs of evaluation from a parametric study realised on a generic system. The results of the three methods were then discussed. Finally, as a perspective, the last study will approach crash mitigation. As a consequence of an active safety system response, the vehicle impact speed is reduced. The effect of speed reduction on variations in impact conditions will be then addressed to measure the potential safety impact of these systems on pedestrian protection.