Underwater inspection system developed by Fraunhofer scientists
The Fraunhofer Institute for Applied Optics and Precision Engineering (IOF) in Jena has developed a 3D system for inspecting pipework and other structures underwater. The device, containing sensor and camera technology, can be used at up to a depth of 40 metres. It is approximately 2m2 and can be held by a diver like an underwater camera.
The prototype was created as part of an international research project together with the 4H Jena Engineering and the Norwegian Research Institute, Christian Michelsen Research (CMR). Fraunhofer IOF will present the system at the Hannover trade fair from 13-17 April.
The 3D system was designed primarily for inspecting underwater oil and gas infrastructure like pipelines as part of their upkeep. As part of the project, Fraunhofer IOF was responsible for making the 3D measurement technology suitable for underwater use.
The 3D measurement system projects several striped patterns onto the surface of the part to be examined. Two cameras then record the light patterns to determine the shape of the object. The diver needs 0.2 seconds for each 3D scan and can check underwater whether they are usable. The data can be loaded to a computer at a later date, which evaluates the information and makes suggestions for possible repair measures. ‘For example, it can be decided whether rust has corroded too deeply or if a defect in the pipe presents a problem or not,’ said Dr Peter Kühmstedt, scientist at the IOF.
The system had to be easy to use in order for a diver to operate it, and it had to be mechanically and thermally stable, as temperatures can fluctuate depending on depth and sea currents. The cabling and electronics also had to be very compact.
Dr Kühmstedt commented that maintaining underwater infrastructure is costly for energy companies, and that the current technologies for inspecting structures underwater are either too slow or operated at too large a standoff distance.
‘In the next step we want to optimise the 3D measurement system for greater depths and broader underwater application fields,’ added Dr Kühmstedt.