Intelligent vehicle highway system sensor and method

Abstract

An object sensor and method using pulsed laser range imaging technology is adapted for determining the velocity and three dimensional profile of a vehicle passing the sensor for classifying the type of vehicle for use in Intelligent Vehicle Highway Systems. A pair of scanned laser beams are provided by splitting a continuously pulsed laser beam from a transmitter and an optical receiver determines the presence of a vehicle in a predetermined zone such as a highway weigh station or toll booth. Range, angle and time data are collected and stored for use in determining the speed of the vehicle passing the sensor and its three dimensional profile. Forward and backward scanned beams are provided using alternate embodiments of a rotating mirror and using two transmitters/receivers in another embodiment. The pulsed energy is sent into the two divergent beams, which are received as reflective energy in a receiver. The receiver accepts reflections from the beams and provides inputs for purposes of determining time of flight, and for measuring the time interval between interceptions of the two divergent beams for a given vehicle. An encoder tracks the position of the mirror for providing angle data with associated range measurements. The vehicle speed is calculated for range data collected when the vehicle passes through the forward and backward scanned beams. Three dimensional profiles are compared with preselected vehicle profiles for classifying the vehicle.