An experimental technique to track mooring cables in small scale models using image processing

Obtaining information about the motion of mooring cables in small scale models in laboratories can be difficult. To help mend this limitation we present a proof of concept of an experimental technique to track mooring cables. Our technique records underwater videos of cables and then applies image processing to extract the coordinates of the complete medial axis of the cables. Using video acquisition has little interference in the experiments and the processing algorithm performs well even under sub-optimal contrast conditions. All the experimental steps are executed underwater, avoiding the need to simplify complex physical models due to visibility or access constraints. Since the whole length of the cable is fully captured on video, any singularity or quick motion (such as those caused by wave energy converters) is adequately detected. Also, the technique yields an acceptable error when compared to directly measured values. With this technique it is possible to acquire important information about the dynamics of mooring cables.