Place-trading AUVs designed for longer oceanographic missions
Although AUVs (autonomous underwater vehicles) excel at gathering marine data without human intervention, they're still limited by battery life. Texas startup Terradepth has set out to address that problem, with a novel tag-team system.
The technology is centred around a new type of un-crewed autonomous submersible, known as an AxV. Two (or more) of these vehicles are deployed together, with one of them travelling along the surface, and the other following along at a depth of up to 6,000 m (19,685 ft). They stay in constant communication with one another via acoustic signals.
While the topside AxV gathers sea surface data, it is also communicating via satellite with a shore-based operations center. It additionally navigates by GPS (which doesn't work underwater), and it charges its battery pack by occasionally running a fuel-burning generator.
Such a generator couldn't function beneath the surface, as internal combustion engines require air in order to "breathe."
The submerged AxV likewise gathers undersea data, running purely on battery power. When that battery starts getting low, the vehicle automatically surfaces near its counterpart. It then fires up its generator and starts recharging its battery, while the AxV that had been traveling at the surface submerges to take its place underwater.
In this way, the two AxVs can keep traveling as long as their periodically used fuel supply lasts, continuing to trade places so that both surface and undersea data is constantly being gathered. An air-breathing hydrogen fuel cell system is in the works, which could ultimately serve as a longer-range, more eco-friendly alternative to the generator.
Terradepth co-CEO Joe Wolfel tells us that the baseline AxV was successfully sea trialed last month, and that other aspects of the system are now in final testing. He adds that the technology should be commercially available by the first quarter of 2022.