Blue Crawfish Goes Swimming: Hardware Architecture of a Crawling Skid for Underwater Maintenance with a BlueROV2

Underwater Robots are used for inspecting offshore structures like foundations of oil and gas platforms or wind turbines for many years. Nevertheless, due to the lack of technical solutions, much of the maintenance work still has to be performed by professional divers. This involves high risks and high costs. To solve this problem current research focuses on a type of underwater vehicles called “crawler”. The concept means vehicles that use a direct contact to underwater structures to crawl along the surface and being less influenced by currents. One such robot that has recently been developed by the Fraunhofer research group Smart Ocean Technologies in Germany is introduced in this paper. An existing BlueROV2 Heavy from Blue Robotics was modified by adding a crawling skid underneath the robot, to which either a linear unit for anti-corrosion coating or a reading device for ultrasonic fatigue crack detection could be attached. While the project presented interesting challenges in several areas of hardware and software integration, this paper focuses on the hardware architecture of the“Crawfish” named vehicle.