Mobile parallel robot for assembly and repair of ITER vacuum vessel

Purpose – The purpose of this paper is to build up a parallel robot for assembling, machining and repairing of the vacuum vessel of the international thermonuclear experimental reactor (ITER). Design/methodology/approach – The process of assembling and machining of the vacuum vessel need a special robot. By studying the structure of the vacuum vessel, a novel parallel robot is built, which has ten degrees of freedom driven by water hydraulic cylinders and electrical servo motors. Kinematic models for the redundant degree robot have been defined. A prototype has been built. Experiments for machine cutting and laser welding were carried out. Findings – The parallel robot is capable of holding all necessary machining tools and welding end‐effectors in all positions accurately and stably inside the vacuum vessel sector. The kinematic models appeared to be complex because of the redundant structure of the robot, and an optimization algorithm ensuring the maximum stiffness during the robot motion helps to find the solution in the trajectory planning. The entire design and testing process of the robot appeared to be a very complex task due to the high specialization of the manufacturing technology needed in the ITER reactor, while the results demonstrate the applicability of the proposed solutions quite well. Originality/value – Offers not only a device but also a methodology for the assembling and repairing of ITER by means of a parallel robot.