The main objective of this experiment was to evaluate the performance of the extended and enhanced version of the NOPTILUS system on a large-scale, open-sea experiment. Operating in open-sea, especially in oceans, the navigation procedure faces several non-trivial problems, such as strong currents, limited communication, severe weather conditions etc. Additionally, this is the first experiment in which we incorporate different sensor modalities. Half of the squad was equipped with single beams DVLs while the other half employed multi-beam sensors.
In order to tackle the open-sea challenges, the new version of the NOPTILUS system incorporates an advanced motion control module that is capable to compensate strong currents, disturbances and turbulences.
Moreover, the final version of the NOPTILUS system utilizes an improved version of the generic plug-n-play web-system, which allows the operation of larger squads. The developed tool is now capable to split the operation procedure in distinct, non-overlapped, timestamps. Based on the size of the squad, the web-system automatically schedules the transmission of the navigation instructions so as, on the one hand, to meet the available bandwidth requirements, while on the other side of the spectrum, to avoid possible congestion issues.
To the best of our knowledge this is the first time that a heterogeneous squad of AUVs is capable of fully autonomous navigate in an unknown open sea area, in order to map the underwater surface of the benthic environment and simultaneously to track the movements of a moving target, in an cooperative fashion.