Spherical robots eyeball nuclear pipework

28 July 2011

Small, ball-shaped robots are being developed by researchers in the USA to inspect underground pipes at nuclear power plants for corrosion.


Plant inspectors usually employ indirect methods to monitor buried pipework, such as running an electric current through them to identify corroded sections or using ultrasound technology to look for cracks because direct monitoring would require digging up the pipes to visually inspect them, which is a costly and time-intensive operation.


Researchers at the Massachusetts Institute of Technology (MIT) are now developing small, egg-shaped robots that will be able to navigate their way around underground pipe networks checking for cracks and corrosion. Equipped with cameras, the robots would be able to transmit images in real-time.


Ball robots (MIT)
A cut-away of the robotic ball being developed by MIT researchers


Harry Asada, the Ford Professor of Engineering in the Department of Mechanical Engineering and director of MIT's d'Arbeloff Laboratory for Information Systems and Technology, is leading the team.


The robotic devices take the shape of smooth metallic balls, with no visible signs of propellers or rudders to move and steer them through an underwater environment. Asada said that a robot fitted with any "appendages" could easily get stuck inside pipes due to the various internal structures like sensor probes and joints. "So we had to make [our design] extremely fail-safe," he said.


The researchers have devised a network of special Y-shaped valves that can be created using 3D printing across the surface of the device. By closing certain valves, thereby channelling jets of water through others, the spherical robots can be propelled in a particular direction.


Originally it had been planned that the robots would use their onboard cameras to take and store images of the interior of the pipes. The devices would then be retrieved and the images examined. However, Asada and his team now intend to equip the devices with wireless underwater communications, using laser optics to transmit images in real-time across distances of up to 100 metres. They are also working on an "eyeball" mechanism that would enable the camera to pan and tilt while the robot is stationary. To achieve this, the researchers have installed a two-axis pivoting support system that enables them to change the device's centre of gravity.


Asada said that he envisages the robots as short-term, disposable patrollers, able to inspect pipes for several missions before being disposed of.


Researched and written

by World Nuclear News