Abstract
The logic and on-board equipment of a lane departure warning system (LDWS) are presented. As the key of the system, the image processing reasons the evidential facts that a lane boundary maintains directional continuity and divides two regions with different intensity, and the lane shape has the symmetry with respect to the center of lane. A distribution function (DF) is formulated for the reasoning the facts and a recursive filter of the DF based on a moving sum plays the role of reducing the noise effect. In addition, a warning algorithm relies on the symmetrical property. The proposed on-board system utilizes an FPGA for an early processing of edge detection and DSP chip as the CPU of the logic to realize real-time processing. In the FPGA-based processing, gradient-based edge operator produces two physical quantities, magnitude and direction, in real time. Followed by the processing, the main logic in the CPU recognizes whether the vehicle deviates from the center of lane. The system is proved its efficiency and applicability of commercial scale by ride demonstration on highway.