This cut-away of the Explorer class AUV, developed by International Submarine Engineering in Canada, shows the various technologies that allow it to operate autonomously and collect information about its environment (see main story).
At the front of the vehicle is an obstacle avoidance system (OAS) and the scientific hardware – the side-scan and bathymetric echosounder (‘sonar payload’). A variable ballast (VB) system helps the AUV maintain its position in the water.
An acoustic modem enables communication with the vehicle when it’s below the surface, to transfer data such as vehicle status. When the vehicle is at the surface, the AUV team can exchange sensor data and updated mission tasks over WiFi.
The Doppler Velocity Log (DVL) is a velocity tracker to help calculate the distance travelled. The Acoustic Doppler Current Profiler (ACDP) measures water current velocities over a depth range using the Doppler effect of sound waves scattered back from particles within the water column.
The AUV is powered by rechargeable lithium ion batteries for 24 hours (140 km). This endurance can be doubled with a second battery.
The USBL, which stands for ‘Ultra-Short Base Line’, is part of the AUV’s navigation system. VCC and DSPC relate to the AUV’s power supply and information processing respectively.
The pop-up buoy and drop weight at each end of the AUV are part of its safety system. The drop weight is released when the AUV needs to quickly return to the surface in an emergency. The pop-up buoy can be triggered acoustically, releasing a floating tow line to aid in recovery.