Vehicle Positioning and Trajectory Tracking by Infrared Signal-Direction Discrimination for Short-Range Vehicle-To-Infrastructure Communication Systems

In this paper, we propose a reliable method to determine the coming direction of an infrared signal, where the direction of the signal sent by the vehicle relative to the receiver is determined by amplitude comparison. We utilize a simple symmetric structure comprising four identical planar receiving modules, each with a specific tilt angle relative to the receiving plane, to construct the receiver. The coming direction of the signal is extracted by comparing the signal strengths received by these four receiving modules. With the aid of a simple geometric relation, the trajectory of a vehicle is tracked, i.e., its positions are located, from the coming direction of the signal originated from this vehicle when it travels through the communication area of the system. For several vehicles simultaneously appearing in the communication area, the vehicles can be distinguished in the frequency domain from different frequencies sent by different vehicles. Our signal-direction discriminator proposed in this paper is able to locate the position of the vehicle in a communication area of 6 m in width and 20 m in length. In the lateral direction, this area sufficiently covers a typical traffic lane; in the longitudinal direction, it meets the general requirements of shorter than 20 m for common short-range vehicle-To-infrastructure communication systems, such as electronic-Toll-collection applications.