• UFRJ Nautilus

Echolocation - Possibilities of underwater echolocation

Updated: May 7

Echolocation is the capacity for emission and analysis or timing of ultrasonic waves used in the survival of animals, such as hunting, location, communication; from the observation and study of these resources, technologies were developed that are used in different places, such as sonar in submarines, radar in airplanes, ultrasound in medicine, and can even be applied in autonomous vehicles.

We can exemplify echolocation as a set of headphones and 1 loudspeaker in which this device emits a sound wave that reflects on some surface and it’s captured by the headphones, according to the frequency and / or time of the received sound it is possible to estimate the distance of objects or even its own position.

When we deal with submarines, the impossibility of using GPS, since it does not work under water, becomes a difficult problem to be solved. Several researches were done to try to solve it, one of them is based on the use of buoys on the surface that receive acoustic signals from the underwater vehicle, which then measure the time of arrival of these signals by sending them to a control center. These shipments are done cyclically, and triangulations are done at the control center to find the position of the submarine.

However, when dealing with AUVs (Autonomous Submarine Vehicles) and many other types of submarines, this technique becomes useless since the central idea is not to exist with no external control over the robot. Oil companies, for example, seek to find echolocation technology that allows an AUV to make a repair on the platform, as opposed to how they are currently done using ROVs (Remotely operated underwater vehicle) or even divers for such a service.

Example of ROV

Example of AUV

In our AUV we use echolocation to know the position of the robot during the race. We use 4 hydrophones to capture a pinger that exists in the middle of the pool in which the competition takes place, and due to the strategic position of the hydrophones and mathematical techniques, such as the Fourier transform, we are able to know the position of the pinger and consequently the robot.

Even today, studies on echolocation are carried out, one of them made by engineers and researchers from the Virginia Tech Institute aimed to study the echolocation of bats and for that they reproduced a bat head in which the ears could move. This research suggests that horseshoe bats can move your ears to obtain different sound qualities and functions for which they will be useful.

Representation of echolocation performed by bats

However, issues such as the temporal relationship between ear deformation, echoes received and communication between bats remains open, so we can see that the echolocation on the surface has not yet been fully explored and that if done, it can bring great advances in autonomous vehicles since sonar does not have the desired effect out of the water.

Written by Ney Rafael.


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