Adaptable legged-magnetic adhesion tracked wheel robotic platform for misaligned mooring chain climbing and inspection

Mooring chains used to stabilise offshore floating platforms are often subjected to harsh environmental conditions on a daily basis, i.e. high tidal waves, storms, etc. Chain breaking can lead to vessel drift and serious damage such as riser rupture, production shutdown and hydrocarbon release. Therefore, the integrity assessment of chain links is vital, and regular inspection is mandatory for offshore structures. Currently, structural health monitoring of chain links is conducted using either ROV’s which comes at a high cost or by manual means which increases the danger to human operators. This paper presents a Cartesian legged tracked-wheel crawler robot developed for mooring chain inspection. The proposed robot addresses the misalignment condition of the mooring chains which is commonly evident in in-situ conditions. The mooring chain misalignment is investigated mathematically and used as a design parameter for the proposed robot. The robot is validated with laboratory based climbing experiments. The robot can be used as a platform to convey equipment, i.e. tools for non-destructive testing/evaluation applications.