CT-Arm (short for coupled tendon-driven arm) is an articulated arm driven by wires. Since the motors are all located in the base, the links can be light-weight, and less energy is needed to move the arm. With several joints, CT-Arm is also able to navigate inside narrow spaces.
The concept was first proposed by Prof. Hirose several decades ago, but recently an improved version of CT-Arm saw action in an unexpected place: the No. 1 Fukushima Nuclear Power Plant.
The power plant was the stage of the nuclear accident of 2011, when some of the reactor building suffered catastrophic failure due to Hydrogen explosions. Even now, the No. 1 reactor building remains mostly untouched due to the complexity of the debris - attempting to remove the damaged structure may cause it to collapse and fall on top of the used nuclear fuel rods, which still remain inside the building.
It is important to create a detailed 3D map of the debris, but no person can go inside the building due to the extremely high levels of radiation. Here is where CT-Arm made a difference: in November 2016, in collaboration with Shimizu Corporation, CT-Arm was used to go inside the debris of the reactor building, moving among distorted metal frames, and to acquire high-resolution pictures and videos of the damaged structure from a wide variety of angles.
CT-Arm collected invaluable information, which was used to build a highly detailed 3D model of the damaged reactor building. Thanks to this information, it is now possible to plan the removal of the debris in a safe and stable way, paving the way for the decomissioning of the nuclear reactor.