Optical and electronic design for a field prototype of a laser-based vehicle delineation detection system

A field prototype of a laser-based non-intrusive vehicle detection system h as been developed for the measurement of delineations of moving vehicles on the highway. This prototype is based on our previous research on the princ iple of the measurement. The detection system uses two laser lines that are projected onto the ground as probes. The reflected light is collected and focused onto a photodiode array by an optical system. Vehicle presence is d etected based on the absence of reflected laser light. By placing two ident ical laser/sensor pairs at a known distance apart, the speed of both the fr ont and rear of a vehicle can be calculated based on the times when each se nsor is triggered. The detector data are acquired and processed by a realti me system to obtain speed, acceleration, and length of a detected vehicle. The travel time of a vehicle can be acquired by detecting a vehicle at the beginning of a link and re-identifying the same vehicle at the end of the l ink. Several tests have been done with the field prototype system on the hi ghway. The testing results show that the system can obtain the accuracy of measurement necessary to distinguish between moving vehicles on the highway . This article describes the design and implementation of each functional c omponent of an advanced version of the field prototype system. (C) 2001 Els evier Science Ltd. All rights reserved.