Evaluation and Design Recommendations for a Folding Morphing-wheg Robot for Nuclear Characterisation

This paper explores the design and development of a folding robot required to survey and characterize nuclear facilities only accessible via 150 mm diameter entry ducts. The enclosed legacy facilities at old nuclear sites like Sellafield in the UK have this sort of limited access. When a site reaches the end of its operational life, it must be decommissioned and the resulting waste material must be safely disposed of. The condition, radioactive characteristics, and accessibility of the enclosed environments are unknown; for decommissioning to occur, these environments must be mapped and characterized. For a robot to carry out this task, one of the key requirements is the ability of the robot to traverse rough terrain and obstacles that could be found inside the facility. To accommodate this, while fitting through the entry duct, the chosen design utilizes morphing whegs (i.e., wheel-legs) for locomotion. These are shape-changing wheels that can open out into a set of legs that rotate around an axle, allowing greater traction, diameter, and object traversal ability than wheels alone. The design and morphology of a folding morphing-wheg robot for nuclear characterization, as well as the manufacture and testing of a prototype, is discussed in this paper. A preliminary evaluation of the robot has shown it is capable of climbing up a maximum step height of 150 mm while having a wheel dimension of 100 mm and being able to fit through a 150 mm duct.