Optical axle-counting equipment

An axle-counting equipment using a laser-scanning range finder has been proposed and developed for the first time in order to improve the accuracy of vehicle classification in nonstop electronic toll collection systems. Because of laser-scanning at the high frequency the high-speed response of 6 msec for the axle-detection allowed a vehicle traveling at speed over 60 km/h. Although the wheel is black colored, the laser-scanning range finder based on optical triangulation clearly produced range images. The equipment using newly developed model matching algorithm successfully distinguished into three states, that are, road surface, axle on road, and the lower body of vehicle above road. Because of noncontact detection, high durability should be expected.