CAMBRIDGE, MA, JULY 26, 2017 -- Access to clean, safe water is one of the world's pressing needs, yet today's water distribution systems lose an average of 20 percent of their supply because of leaks. These leaks not only make shortages worse but also can cause serious structural damage to buildings and roads by undermining foundations.
Unfortunately, leak detection systems are expensive and slow to operate -- and they don't work well in systems that use wood, clay, or plastic pipes, which account for the majority of systems in the developing world.
Now, a new system developed by researchers at MIT could provide a fast, inexpensive solution that can find even tiny leaks with pinpoint precision, no matter what the pipes are made of.
The system, which has been under development and testing for nine years by professor of mechanical engineering Kamal Youcef-Toumi, graduate student You Wu, and two others, will be described in detail at the upcoming IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) in September. Meanwhile, the team is carrying out tests this summer on 12-inch concrete water-distribution pipes under the city of Monterrey, Mexico.
The system uses a small, rubbery robotic device that looks something like an oversized badminton birdie. The device can be inserted into the water system through any fire hydrant. It then moves passively with the flow, logging its position as it goes. It detects even small variations in pressure by sensing the pull at the edges of its soft rubber skirt, which fills the diameter of of the pipe.
The device is then retrieved using a net through another hydrant, and its data is uploaded. No digging is required, and there is no need for any interruption of the water service. In addition to the passive device that is pushed by the water flow, the team also produced an active version that can control its motion.
Monterrey itself has a strong incentive to take part in this study, since it loses an estimated 40 percent of its water supply to leaks every year, costing the city about $80 million in lost revenue. Leaks can also lead to contamination of the water supply when polluted water backs up into the distribution pipes.
The MIT team, called PipeGuard, intends to commercialize its robotic detection system to help alleviate such losses. In Saudi Arabia, where most drinking water is provided through expensive desalination plants, some 33 percent is lost through leakage. That's why that desert nation's King Fahd University of Petroleum and Minerals has sponsored and collaborated on much of the MIT team's work, including successful field tests there earlier this year that resulted in some further design improvements to the system, Youcef-Toumi says.
Those tests, in a mile-long section of 2-inch rusty pipe provided by Pipetech LLC, a pipeline service company in Al Khobar, Saudi Arabia, that frequently uses the same pipe system for validating and certifying pipeline technologies. The tests, in pipes with many bends, T-joints, and connections, involved creating an artif icial leak for the robot to find. The robot did so successfully, distinguishing the characteristics of the leak from false alarms caused by pressure variations or changes in pipe size, roughness, or orientation.
"We put the robot in from one joint, and took it out from the other. We tried it 14 times over three days, and it completed the inspection every time," Wu says. What's more, it found a leak that was about one gallon per minute, which is one-tenth the minimum size that conventional detection methods can find on average, and a third as large as those systems can find under even the best of conditions.
The next step for the team, after the field tests in Monterrey, is to make a more flexible, collapsible version of their robot that can quickly adapt itself to pipes of different diameters. Under the streets of Boston, for example, there are a mix of 6-, 8- and 12-inch pipes to navigate -- many of them installed so long ago that the city doesn't even have accurate maps of their locations. The robot would expand "like an umbrella," Wu says, to adapt to each pipe.
