Variable pitch! Waterproof! This thing is awesome. Surely there is different tuning when it's in water vs when it's not, right? How do you detect the transition? Motor currents? This is a really neat project!
In their report (https://gitlab.com/hybrid-drone/paper) the authors mention that they implemented one controller for flying and another for diving. The transition seems to be initiated manually, but they propose a few ways of automatic detection and transition.
It's interesting how simple this looks, off the shelf parts, and 3D printed components. I'm almost surprised this doesn't already exist after looking at it.
Any ideas how the signal is transmitted once the drone is underwater? Typical RC transmitters run 2.4 GHz. Some systems use 700 MHz. The former wouldn't penetrate at all, the latter might penetrate to a shallow depth, but I think that what's shown in the video is deep enough that the signal would get attenuated. There doesn't seem to be a tether and the drone doesn't seem to have any computer vision capabilities to fly itself whilst under water. I wonder how they solved this.
IMU that determines rotation rates and acceleration without vision. A drone can fly and hold attitude with some accuracy without any outside help, it doesn’t need cameras or outside control. Only GPS to counteract drifting but that can be neglected in the very short term.
As far as I can tell from their report (https://gitlab.com/hybrid-drone/paper), the authors did not consider underwater RF transmissions in their prototype design and simply use standard COTS components typically used for DIY UAVs.
As an undergrad project this is rather impressive. But those motors do not look very water resistant. We all know that that shape and those blades are not very efficient in the water. And as others mention the RF signal probably cuts out at a few meters (probably worse in salt water).
Definitely impressive as a proof of concept. A lot of the other problems can be solved with iteration. There are some IP67-rated drone motors meant to both fly and run underwater (available from Westmag for example).
There might be less that can be done about the underwater drag, but if it doesn't need to go long distances underwater that's not as much of a problem. For the RF signal, it can either run autonomously underwater, or use a fibre-optic umbilical, or even convert from an umbilical to wireless when it takes to the air.
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[ 553 ms ] story [ 838 ms ] threadOr for the more cynical, replace "search and rescue" with "military covert ops".
I’d expect it to have more range underwater than a typical quadcoter has through air. And much longer “flight” time.
But I doubt it gains enough to compete with a fixed wing drone using the same battery.
There might be less that can be done about the underwater drag, but if it doesn't need to go long distances underwater that's not as much of a problem. For the RF signal, it can either run autonomously underwater, or use a fibre-optic umbilical, or even convert from an umbilical to wireless when it takes to the air.
"Hybrid" usually means a combination of features from two different things.
For instance, a car with electric & internal combustion engines.
But here they are using "hybrid" to mean a combination of capabilities. That's different than features.
Also, "hybrid done" already has a meaning:
https://en.wikipedia.org/wiki/Hybrid_drone