Sea drones help explore the oceans for wreckages and mines

A new underwater drone named Evie (Ellipsoidal Vehicle for Inspection and Exploration), is being created that can scan the oceans to search for plane wreckages and mines for example. The drone uses a number of jets to move through the water and change direction, as well as interchangeable sensors depending on the drone's mission. Evie can work individually, or as part of a group of drones, that can communicate with each other and scan sections of the sea bed. It offers a cost-effective, practical approach to sea exploration, rather than using expensive autonomous underwater vehicles. 

When Sampriti Bhattacharyya read about a controversial US Navy scheme in which dolphins try to locate sea mines she realised the true potential of the robot she was working on.

Bhattacharyya’s underwater device, about the size of a football, had been developed at Massachusetts Institute of Technology (MIT) as a tool to detect cracks or splits in nuclear reactor tanks. When Bhattacharyya saw that dolphins were being used to detect mines and locate equipment lost underwater, a world of possibilities opened up – among them mapping the ocean floor or scanning the hull of ships for contraband.

“That made me realise that my robot could be very useful. It is so cheap and easy to make, I could actually make a bunch of them and they could spread out and scan ship hulls,” says the Indian engineer.

Bhattacharyya is developing the prototype of an underwater drone which she hopes will provide a cheap way to map vast swaths of the ocean and chart the underwater landscape.

The drones, named Evie (Ellipsoidal Vehicle for Inspection and Exploration), could also be used to search for plane wreckage, such as in the case of missing Malaysia Airlines flight MH370, she says.

The drone, from Bhattacharyya’s company Hydroswarm, uses a series of jets to propel itself through the water and manoeuvre in different directions. It includes a battery and various interchangeable sensors depending on what task the drone is carrying out.

It could plug in electronics for monitoring the quality of water or for measuring pollution from an oil spill. “It is a platform where you can plug and play any kinds of sensors that you want,” she says. “It is very much like an aerial drone.”

The Hydroswarm sea drone and its inventor Sampriti Bhattacharyya. Photograph: Hydroswarm

Cameras can also be installed, although they will only work where natural light illuminates the water. Below that point, ultrasound sensors can be used to return images. The first drones will be able to travel up to 250m (820ft) below the surface, according to Bhattacharyya, whose aims to deepen the search in later models.

The drones are being designed to work either individually or as a group, she says, and will be able to communicate with each other. A group of the drones all individually fitted with hydrophones – microphones that can detect soundwaves underwater – could be used to scan sections of the seabed. This swarm of devices would be a more cost-effective and practical approach than using larger and more expensive autonomous underwater vehicles (AUVs), robots which travel underwater.

“I was thinking that we don’t have the technology to find a massive 747 in the ocean and if you break down the physics of the problem, all you are searching for is a ping [from the black box]. And if you break it down further all you need to hear the ping is a cheap hydrophone,” she says.

“Why not have a network of distributed hydrophones over a large area that can all sync. Each of them has their own ID and location. If I hear a ping after a transmission, they all rise up. If any of them have heard it, they upload it [the details] to a satellite and you know where the ping is coming from.”

Hydroswarm’s Prototype Demo Reel.

Her principle focus for the drones is to map the ocean floor, an area which is largely undetailed at present. In 2014, the Scripps Institution of Oceanography in California published a map of the ocean floor with a resolution of 5km per pixel, using satellites to detail the landscape including large underwater mountains and ridges. More detailed maps made using ship sonar systems have mapped between 10% and 15%, about the size of Africa.

Bhattacharyya says the drones could also help identify areas populated by particular fish, or plot dying coral reefs.

“We know less about the ocean than we do about the moon’s surface. What I want to do is make a whole map of the ocean,” she says.

Her ultimate ambition, though, is to map the Mariana Trench, the deepest part of the world’s oceans and found in the western Pacific. But at 11km deep, the Mariana Trench is many times deeper than the maximum range of the early drone models.

The drones are still being tested in labs and Bhattacharyya admits she will have many hurdles in front of her if she wants to launch Evie on the market in 18 months. “Most of us don’t know much about the ocean and there will be a lot of new difficulties we have no idea how to deal with; that we will have to encounter when we put it in the middle of the ocean.”

A consumer version of the drone is also planned. It will operate in a similar manner to aeriel drones currently on the market which can film the user from a distance, used often by skiers when skiing or in ground-controlled aerial photography. Bhattacharyya estimates these will cost between £700 ($1,000) and £1,000 ($1,500).