Measurement techniques for underwater

3D acquisition and monitoring of large underwater structures using LiDAR

Offshore wind turbines, tidal lift power plants and drilling platforms are structures that have to be erected partly or wholly in water. Such structures require regular and as objective as possible inspection and testing. Today, this is carried out completely visually by divers, as no suitable measuring systems are available. With several thousand wind turbines alone in the North Sea and Baltic Sea and a multitude of drilling platforms worldwide, the inspection can only be carried out with an enormous expenditure of time and great risks for the personnel involved.

Within the scope of a research project, Fraunhofer IPM is developing a laser-based system for the 3D inspection of large underwater structures. The measuring system works based on a time-of-flight method having been fundamentally enhanced for use in the turbid medium of water. In addition to the hardware, the scanning system includes algorithms for fast and reliable data evaluation and interpretation. The complete system already exists as a prototype.

By analyzing several reflected pulses, the system ignores both results that do not originate from scattered light and interfering particles in the water. The integration of the complete system into an appropriate pressure housing and the use of special water-suitable components enables the use on remote-controlled or autonomous underwater vehicles. For the first time this will allow for efficiently obtaining very accurate 3D data for a wide range of underwater inspection tasks.

The system has so far been tested under laboratory conditions. First tests in the sea are planned for the coming weeks. We have been able to involve several companies and authorities for this purpose, including the BSH (Federal Maritime and Hydrographic Agency). The system is expected to be available for use in 2020.


laser scanning

3D laser scanning of an offshore wind turbine foundation installed on a ROV. How does it work?