An experimental study of obstacles and pedestrian classification by relative velocity distribution on urban-narrow bicycle-pedestrian road with 77 GHz FMCW radar

Abstract

In recent years, the number of people using the bicycle as a means of transportation has increased due to heightened health awareness and environmental protection and COVID-19 pandemic, instead of public such as train and bus. Further, bicycle-related traffic accidents have rapidly increased due to the rapid growth of the food-delivery business with bicycle use, and thus countermeasures are urgently needed. In this paper, we propose a method for a bicycle to detect pedestrian separating from road obstacles such as guard poles and guardrails installed in an urban-narrow bicycle-pedestrian road with the use of frequency modulated continuous wave multi-input multi-output (FMCW-MIMO) radar. In the proposed method, from the distribution of the relative velocity of the detected objects, the objects gathering around the mode of the relative-velocity distribution are judged as the road obstacles, and the objects far from the mode are judged as pedestrian. In an experiment, a bicycle equipped with 77 GHz-band FMCW-MIMO radar, ran at a speed of 2 m/s and a pedestrian walked ahead at a speed of 1 m/s in a narrow bicycle-pedestrian road (school zone) in central Tokyo. Experimental result shows that the pedestrian was detected with about 1m/s-higher relative velocity than around 1.5 m/s of mode relative velocity, where road obstacles group distributed in the range of ±0.5 m/s.