Robust Sensing of Approaching Vehicles Relying on Acoustic Cue

This paper proposes a robust sensing technique for localizing an approaching vehicle relying on an acoustic cue. A camera and a radar system are commonly used as sensors for active safety systems. However, such sensors do not work well in a blind spot such as a blind junction of a highway. On the other hands, various acoustical noises caused by a cruising vehicle arrive at the blind spot. Those acoustic cues are available for achieving robust sensing of surrounding vehicles. It is necessary to extract a robust spatial feature from noisy acoustical observations. In this paper, the spatio-temporal gradient method is employed for the feature extraction, and the spatial feature is filtered out through sequential state estimation. Feasibility of the proposed method is confirmed with real acoustical observations, which are obtained by microphones outside a cruising vehicle. The filtering process can be done in real time, because its real-time factor is 0.096 using a 2.6 GHz Intel Core i7 processor.