A tight curve warning system using FSK visible light and road-to-vehicle communication

Rolling accidents often happen on the tight curves, so road-to-vehicle communication is required. In this paper we apply visible light communication to road-to-vehicle communication and propose a tight curve warning system. We use the hierarchical coding of FSK because a receiver can receive both low frequency data and high frequency data when it is close to the sender, and it can receive only low frequency data when it is far away from the sender. We made a 1/32 scale prototype model and the experimental results show its ability to distinguish the communication distance from the frequency. The car on our prototype system put on its brakes 2 m from an LED using 16.6 kHz.