AI Helps Inspectors Keep an Eye on Inspection Status

By Tom Der, Vice President, ITS Solutions and Engineering, International Road Dynamics (IRD)

Automated CVSA decal reader systems based on artificial intelligence (AI) and machine vision are a reality. The use of AI enables high read rates of CVSA decals, making a CVSA decal reader suitable for automatic prescreening of commercial motor vehicles in advance of weigh stations.

While an experienced inspector can take a glance at a CVSA decal and tell when a vehicle was last inspected, it is a complex task for a computer. Fortunately, AI-specific processing units coupled with powerful industrial computers are enabling deep neural network and computer vision-based transportation system applications.

Based on the information printed on the decal, the decal color, and whether one or both corners are clipped, it is possible for automated CVSA decal reader systems to determine when a commercial motor vehicle was last inspected and whether the vehicle is due to be inspected again.

The CVSA decal reading application uses machine learning’s pattern recognition to extract windshield-mounted decal parameters from video images of commercial motor vehicles. Two convolutional neural networks work concurrently – first to recognize the windshield, then to detect the decal and its color, and finally the digit, edge detection and classification.

This all happens quickly enough that the information is read in real time and a determination whether to send the truck for inspection is made immediately by the roadside electronics. If the truck has a decal indicating it has been inspected within the last three months, that decal is determined to be valid and the vehicle may be permitted to bypass inspection. If it has been more than three months, the decal has expired. The station inspector will be shown the expired status in the operator display software so they know why the vehicle was sent to report. Much of the work of inspectors at weigh station facilities involves performing visual inspections, including checking for inspection sticker status. AI, coupled with computer vision, offers the opportunity to automate this task and refine pre-selection in advance of the weigh station.

Many weigh stations are already equipped with cameras that provide images of the commercial motor vehicles matched with the weigh-in-motion information, or that provide images for vehicle identification using optical character recognition of the license plate or U.S. Department of Transportation numbers.

Every site’s geometry is different, however, so installation of a camera and illuminator specifically for the CVSA decal reader system may be required. Another consideration is the quality of the image. While the AI system can read very low-resolution images, feedback from users states that high-quality, humanreadable images of the decals are more desirable than cost savings gained from using existing cameras. n