Nature of the Problem

In performing basic research related to development of a real time warning system for oversize vehicles , IEM considered two alternative approaches, one based on use of stereo-3D machine vision methods, and another using a more traditional approach using laser scanning devices. However, during our research and review of commercially available laser scanning devices, IEM determined that current technology places significant limitations on how accurately vehicle dimensions can be measured. Current laser technologies are limited by two fundamental elements: number of points that can be measured per second and scanning rate. Together, these elements will result in reduced the resolution for vehicles travelling at highway speeds.

IEM’s WISE Solution

The ultimate objective for IEM’s intelligent dimensioning system is to be able to measure critical vehicle dimensions (most important is height, but width and length are of interest as well) with sufficient resolution and accuracy to enable alerts to a vehicle if it should approach a bridge or tunnel that is too small. The basic requirements for this application call for accuracy and resolution of no more than one inch.

IEM, in cooperation with the Federal Highway Administration, is investigating alternative technologies that may be applied to improve the resolution and accuracy of laser scanning devices. Current work has concentrated on developing a low cost device that can effectively increase the frequency of range measurements at a reasonable cost. Toward this end, IEM developed a breadboard prototype for a high speed laser rangefinder capable of making several hundred thousand measurements per second (limited mainly by the laser hardware itself and noise levels) with a timing precision of ±0.05 nanoseconds or approximately a half inch.

IEM continues to pursue methods of improving the capabilities for laser scanning and its application for automated vehicle dimensioning.