Towards Safe Autonomous Driving: Challenges of Pedestrian Detection in Rain with Automotive Radar

Environment perception under all weather conditions becomes more important on the next steps towards safe autonomous driving. In this paper, the impact of rain on short-range radar is investigated with regard to pedestrian detection. The characteristics of backscatter generated by rain droplets and pedestrians are analyzed and compared. Thereby, the challenge of measuring pedestrians in rain by short-range radar is discussed. Particularly, the micro-Doppler effect is examined, which is a major feature of the pedestrian radar signature. Based on the theoretical consideration of rain clutter, a procedure for reducing the impact of rain is presented. The resulting micro- Doppler spectrum shows a significant improvement in the performance compared to conventional signal processing techniques.