Radio waves propagate poorly underwater. That’s why underwater drones, also known as underwater remotely operated vehicles (ROVs), must remain tethered to the surface via communications cables to transmit video recordings and control signals. Unfortunately, this limits the robot’s range and can be a hassle because the line can snag on other underwater objects.
As a result, a growing number of civilian drones are being used in the sky for aerial photography, surveillance, delivery, and search and rescue. Still, people haven’t gotten very far with using them underwater. That may change thanks to the Swiss startup Hydromea and its wireless underwater ROV called ExRay.
ExRay uses light instead of a cable. It’s being hailed as the world’s first wireless underwater drone. It can be remotely controlled, sending HD video back in real-time sans any physical connection to the pilot. And, it’s so compact it can fit into a backpack!
Hydromea put out a demo video of an ExRay prototype in a pool (see below). Instead of a tether, it uses the company’s Luma underwater communication system that transmits binary data through the water using rapid light pulses. To be precise, 470-nanometer blue LED light shoots back and forth between two optical modems (one at the surface and one on the ROV).
The transceiver can transmit a signal as fast as ten megabits per second, allowing you to broadcast HD-resolution video from the drone to the operator’s console with virtually no lag.
Hydromea co-founder Alexander Bahr admits there are still some limitations. ExRay has a 50 m (164 ft) communications range in clear water and total darkness, but that figure decreases as turbidity levels and ambient light increase.
However, the company plans to bring the drone’s depth to at least 100 meters (328 ft), which should continue to increase as the technology is developed further. Regardless, the robot is intended to be used for enclosed-space tasks (like inspecting ships’ ballast tanks), so the relatively short range shouldn’t be an issue.
The 70cm-long (27.5 in), 7 kg (15 lb) drone consists of a flat body with a sealed transparent center capsule that houses the battery, tilted camera with a zoom lens, optical transceiver, and the rest of the electronics. It’s equipped with seven hubless thrusters (three horizontal and four vertical), giving it six degrees of freedom maneuverability. It also has two LED headlights.
It can run for six to eight hours on a single full charge.
Hydromea envisions ExRay being used in several inspection scenarios in confined flooded spaces, like closed waterways, hydropower dams, and ballast tanks on ships. It could reduce the cost and time-to-results while also eliminating the safety risks of dangerous inspections currently performed by humans.
Bahr said more detailed specs and pricing would be announced when the drone is commercially released, which should happen late next year.
