Navigating a maze
A perfect challenge for the "ITER Makers"
3 Sep 2018
ITER magnet feeders are 31 critical components that deliver electrical power and cryogenic fluid to the magnets and serve as conduits for instrumentation cables across the warm/cold barrier of the Tokamak. The first feeder component delivered to ITER is the cryostat feedthrough for poloidal field coil #4: a 10-metre, 6.6-tonne component.
Over lunchbreaks and weekends, the ITER Makers used open-source hardware to design and produce a system, complete with a gyroscope, a compass and an accelerometer, capable of showing users the live position of the endoscope inside the cryostat feedthrough.
A cryostat feedthrough for a magnet feeder (seen here in the latest stages of assembly at ASIPP in China), is a maze of pipes and welding that only an endoscope can inspect. But how does one determine the device's orientation? The ITER Makers had an answer ...
A challenging inspection: only an endoscope can fit in this maze of pipes and welding and facilitate the visual inspection. But even with the best endoscope, physical orientation is easily lost and the inspection becomes more difficult—not knowing whether the image is straight, rotated or upside-down.
ITER Makers to the rescue: After an endoscopic inspection of the first feeder, Jaromir Farek of the In-Cryostat Assembly Section contacted the ITER Makers Group to explore how real-time feedback could be given on the endoscope's position. (The ITER Makers Group—a recently established club with a small "FabLab" onsite—is a space where ITER Organization collaborators can work on personal and group projects on their own time, exploring new technologies while sharing tools, equipment and knowledge.)
This was a perfect challenge for the ITER Makers. But time was of the essence, since the next inspection was due in just four days (weekend included).
Quick, a solution! Romain Bourgue, the co-founder of the ITER Makers group, identified a solution: a small position sensor that would integrate a gyroscope, a compass and an accelerometer. This component, similar to the device used in smartphones, would be attached to the end of the endoscope and transmit position information to an Arduino microcontroller. The Arduino would in turn send output to a computer monitor, where a 3D model of the endoscope would rotate and show users the live position of the tool.
Working together during a few fruitful lunchbreaks and a weekend, the group soon had a working prototype, complete with a custom casing fabricated with the Makers' 3D printer.
Now to the real thing! The next steps involved moving from prototype to the real thing. Knowing that the endoscope cable is 5 metres, the Makers soldered the sensor to a 10-metre cable and re-verified its functionality. The sensor then needed to be attached securely to the camera of the endoscope, using heat shrink tubing at the endoscope tip and cable ties to complete the installation.
The inspection took place at the nearby MIFI workshop at the French Alternative Energies and Atomic Energy Commission (CEA) research centre, where the first magnet feeder component is currently stored. With the gyroscopic information telling the endoscope user the exact positioning of the instrument, the inspection was a success.
Romain Bourgue, IT Security & Policy Responsible Officer; Jaromir Farek, Magnet Auxiliaries Structural Specialist; Nuno Pedrosa, Non-Destructive Testing Engineer; Jean Revel, Instrumentation & Control Engineer; and Wan Lijun, Superconducting Auxiliaries Engineer all contributed to the project.