Autonomous Underwater Vehicle for Water Environment Monitoring
Purpose:The main objects of physical and chemical measurements of coast, lakes and rivers have so far been water environment andwater resource issues. However, the demand for these measurements has expanded to CCS and HLW disposal, etc. recently,
and the costs and time of water environment surveys are increasing because three dimensional mapping over wide areas isrequired to make these environmental measurements. Therefore, CRIEPI has introduced the AUV to efficiently obtain three
dimensional distributions of water quality, flow velocity and topography by autonomous sailing along the coast and in lakes,
rivers and dams.
Outlines:
Chemical and physical environments of the sea and lakes are measured by using the ROV (Remotely Operated Vehicle) ingeneral. However, wide-ranging mapping works by the ROV require much time and are limited by climate and ocean conditions. On the other hand, this equipment, which is named AUV (Autonomous Underwater Vehicle), is able to operate at anequal altitude or an equal depth autonomously regardless of the climate and ocean conditions. CRIEPI has installed manykinds of chemical sensors such as a "Nose" in this AUV to specialize in the water environmental survey. In these sensors, theISFET-based pH, ORP and pCO2 sensors developed by CRIEPI are especially suitable for measurement using underwater
vehicles because of their high resolution and fast response.
In addition, the CRIEPI's AUV is also equipped with ADCP (Acoustic Doppler Current Profiler) for measurements of thecurrent direction and the velocity, and with side scanning sonar as an "eye." The general sidescan sonar is usually towed froma surface vessel. We can obtain more precise topographic images than by towing the sidescan sonar since the CRIEPI's AUV
can approach to within a few meters from the bottom of the sea or a lake and can retain this depth while navigating.
1) To survey various water environments such as the distribution of turbid water, chemical composition of water, and thedistribution of phytoplankton along the coast and in lakes, dams and rivers.
2) To map the CO2 leakage and the groundwater seepage from the sea bottom as natural analog studies involved with CCS(carbon dioxide capture and storage) and HLW (high level radioactive waste) disposal.
Specifications:(1) AUV①②③

Weight (in Air) : 45Kg
Maximum Operating depth: 100 mEndurance: 22 hours at optimum speed of 1.5 m/s
8 hours at optimum speed of 2.6 m/s④ Navigation: Hybrid navigation combining LBL and dead reckoning (by DVL and/or GPS)
⑤ Communication: Micro-Modem (ACOMS at underwater) and iridium (satellite telephone on surface)(2) Sensors and objects① Sidescan Sonar: Submarine topography② pH: Hydrogen potential③ ORP: Oxidation-reduction potential④ O2: Dissolved oxygen⑤ pCO2: Dissolved carbon dioxide⑥ OBS: Turbidity⑦ ADCP: Current direction and velocity⑧ CT: Conductivity and temperature⑨ Chlorophyll: Phytoplankton
Location and Date of Installation:
Abiko Area, March 2008

Dissolved
oxygenSidescan Sonar

OBS・Chlorophyll

CRIEPI's AUV

Sensors equipped in AUV

135

Distribution of pH (left) and acoustic
images by sidescan sonar (right)