Vehicle-to-Vehicle Visible Light Phase-Shift Rangefinder Based on the Automotive Lighting

Vehicle-to-vehicle (V2V) distance measurement is at the heart of the trajectory control performed by the vehicles forming an automated platoon. Although several technologies like radar or lidar are already used with great benefits in such applications, they suffer from interference issues justifying the need of redundant sensors. In this paper, a proof of concept of a visible light rangefinder based on the headlamps and taillights of two consecutive vehicles is brought for the first time. The following vehicle sends with its headlamps a square wave that is received, reconstructed and sent back by the preceding vehicle with its taillights. This echo is received and reconstructed by the following vehicle, and finally compared with the initial signal in order to extract the phase-shift in which the V2V distance is contained. A prototype of this system is built using off-the-shelf components and tested for performance evaluation. It is shown that distance measurement is functional up to 25 m and that the measurement resolution is around 24 cm at 10 m, a distance typical for platoons in cruise mode, and with a refresh rate of 506 Hz.