The UK’s Solent has hosted a pioneering autonomous surveying event reports Dag Pike.
Sea Robotics ‘ ASV ‘Harry’
The first time that a hydrographic survey has been carried out using guidance only from pre-planned survey lines or automatically generated lines based on sonar coverage took place at Hurst Point in the Solent. Human control was possible with the equipment but was not required for the operation of the Sea Robotics 2.5 Autonomous Surface Vehicle. This pioneering survey operation was supported by the MCA and the UKHO.
The seabed at Hurst Point in the Western Solent was chosen as the survey site because of its challenging wave conditions and strong tides. There were two stages to this survey operation, the first carried out by an Unmanned Aerial Vehicle to collect high-resolution topographic data which though not normally a hydrographic deliverable is highly accurate data that is very useful to coastal engineers. The SeaRobotics ASV 2.5 was the ASV used for the actual hydrographic survey.
The ASV survey in the main channel was carried out mainly during the period before and after low water when the tidal currents were weaker with the remaining areas surveyed during the other periods in order to reduce the power demands on the ASV batteries. The ASV is trailer launched, allowing it to be deployed from a beach. It then followed a pre-planned line survey with each line generated from information from the previous line so that full coverage is guaranteed. The station keeping achieved was within a ¼ metre of the planned route.
The ASV was equipped with an R2Sonic 2020 Multibeam Sonar, an Applanix POSMV Wavemaster inertial system and an AML X-Base 2 SVP. The software used was a Hypack Hysweep Acquisition system and QPS Qimera Processing Software. An AIS unit was also on board and a normal survey vessel was in attendance for safety patrol.
For the survey the area was divided up into blocks and delays were caused by bad weather but it was completed successfully. The ASV performance was better than anticipated in that the battery life turned out to be approximately 5 hours and that was running at a very high thruster power at times. This ASV autonomous survey system proved to be a cost and time effective method of undertaking a hydrographic survey particularly as it allows for rapid deployment and the results of this survey have been incorporated into UKHO charts.
Source: Maritime Journal