SmartDig Goes Where Satellite Signals Lose Their Accuracy
Why are some excavators wearing what appear to be giant quick-response codes? The QR codes are not the latest e-commerce trend on construction sites but part of a research project at the University of Michigan, Ann Arbor, aimed at making machine controls more accurate in urban settings.
"It's weird," admits Suyang Dong, a researcher at the school's Laboratory for Interactive Visualization in Engineering, speaking of the strange signs. "But we call it a very disruptive technology."
Since last year, Dong and his colleagues have been trying to overcome a problem contractors face using electronic grade controls on city jobsites: Most existing controls rely on GPS signals, which can become less and less reliable as skyscrapers and other urban obstructions stand in the way.
Working under National Science Foundation grants, the research team set out to develop a tool to help operators avoid hitting buried utilities but, in the process, found a way to increase worker productivity. The codes act as positioning markers that, when calibrated, feed an augmented-reality display that tells the operator how deep to dig within an inch of accuracy and at a fraction of the cost of GPS-based systems. "We are trying to make a system that can be as accurate as GPS but with half the cost," says Dong.
It takes about two hours to retrofit and calibrate an excavator, researchers say. A marker sign and a linear encoder, which records the bucket cylinder stroke, are added to the boom. Another on-site marker is set to a known elevation. Hooked into a laptop that contains digital plans of the earthwork, three cameras watch the markers, while a screen displays virtual guides—similar to the warning lines of the rearview cameras in newer cars—for the operator to target.
Although the markers look ungainly, they can be customized for a better fit and finish, Dong says. The system, which the team calls SmartDig, has an estimated price tag of $20,000; it could generate $450 million a year, with 13% annual growth, he adds. As the team establishes a start-up company, testing continues and three patents are pending.
