Pedestrian Detection Strategy in Urban Area: Capacitance Probes and Pedestrians’ Signature

Every year, lives of millions of people are cut short or considerably affected by road accidents. Most of them happen in urban areas where the speed limit is supposed to be below 50 km/h. Active protection devices (such as airbags) attached at the front of the vehicle can help reduce the severity of injuries inflicted in such circumstances. However, the effectiveness of such strategies depends greatly on how well we can anticipate the impact moment of the accident. The physical principle of capacitive coupling can be used to anticipate the impact by detecting the intrusion of the pedestrian in the detection volume of the probe. However, any intrusion into the sensing volume of probe can increase its capacitance like dust deposits on the surface of the capacitive probe, the variation of the air humidity, the air friction on the car's body, which makes the common voltage float among others that influence the capacitance of the probe and make the voltage carried by the probe vary over time. To overcome this problem, we define the concept of “pedestrian signature.” This concept can help us distinguish the presence of a pedestrian in the sensing volume of the probe from any other perturbations. Thus, we can anticipate the moment of impact early enough to trigger protection systems. The analog electronic device, we present in this paper, along with the pedestrian signature can help trigger protection devices to react at the right moment. The same device can also be used as parking aid when the vehicle speed is less than 10 km/h.