Today's water distribution systems lose an average of 20 percent of their supply because of leaks. Current leak-detection systems are expensive and slow to operate, and they don't work well in systems that use wood, clay, or plastic pipes. A robotic system developed by researchers at MIT could provide a fast, inexpensive way to find even tiny leaks with pinpoint precision, no matter what the pipes are made of.
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 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.
The system has been under development and testing for nine years by professor of mechanical engineering Kamal Youcef-Toumi, graduate student You Wu, and two others. The MIT team, called PipeGuard, intends to eventually commercialize the robotic detection system to help alleviate water losses around the globe.
For example, in Saudi Arabia, where most drinking water is provided through expensive desalination plants, some 33 percent is lost through leakage. That's why the country's King Fahd University of Petroleum and Minerals has sponsored and collaborated on much of the MIT team's work. This included successful field tests in Saudi Arabia earlier this year that resulted in some further design improvements to the system. The tests — done in pipes with many bends, T-joints, and connections — involved creating an artificial 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 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.
The value of the robot is not just for reducing water losses, but also for making water services safer and more reliable. When a leak occurs, the force of the water flowing from underground can do serious structural damage. The ability of this system to detect small leaks could enable early detection and repair, long before serious pipe breaks occur.
Not only could the system find leaks in virtually any kind of water pipe, it could also be used for other kinds of pipe distribution systems, such as those for natural gas. The MIT system was actually first developed to detect gas leaks, and later adapted for water pipes. Ultimately, the team hopes, the robot could not just find leaks but also be equipped with a special mechanism they have designed, so that, at least for smaller leaks, it could carry out an instant repair on the spot.