Intelligent vehicle highway system multi-lane sensor and method

Abstract

An Intelligent Vehicle Highway System (IVHS) sensor provides accurate information on real-time traffic conditions that can be used for incident detection, motorist advisories, and traffic management via signals, ramp meters, and the like. A diode-laser-based Vehicle Detector And Classifier (VDAC) measures the presence, speed, and three-dimensional profiles of vehicles passing beneath it within its multi-lane field-of-view coverage. The sensor uses pulsed laser range imaging technology adapted for determining the three-dimensional profile of the vehicle. The VDAC employs a rotating polygon mirror to scan a pulsed laser rangefinder across three lanes of a highway in order to measure the presence, speed, and height profiles of vehicles in all three lanes simultaneously. A receiver accepts reflections from beams transmitted from the sensor and provides inputs for determining time of flight, and a time interval between interceptions of the two divergent beams for the vehicle. An encoder tracks the position of the mirror for providing angle data with associated range measurements. The VDAC high signal-to-noise ratio and good spatial resolution result in highly accurate traffic-parameter measurements.