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Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

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Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#21

Post by bigiain »

knob wrote: post #16

Throwing my idea out there: What if the to propellers are synched. Depending on desired direction, they are "un-synched" ever so slightly. This causes additional thrust on one side of the "duct".

ATH Zurich have a single prop craft that uses just a single channel high speed motor control to stabilise and steer it: https://www.youtube.com/watch?v=P3fM6VwXXFM

I wonder if this maybe has two contra rotating single blade props that they can control quickly enough to be able to speed them up for half a revolution to generate asymmetric thrust to provide pitch and roll?

Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#22

Post by api_or_ipa »

Very interesting. I wondered when someone would try to mesh coaxial rotors [0] with quadcopter use cases.

To make a real co-axial vehicle, you'll need to handle changes in the 3 translational axes (forward/backward, strafe left/right and up/down) as well as the rotational axes. Despite being a complicated movement, it's pretty well understood and Kamov has been making coaxial helicopters for many years.

My best guess based on the video is that there are two contra-rotating fixed pitch props in the middle. This gives you up/down and by varying the speed of the props gives you yaw right/left. A couple of clever ducts forward, aft, left and right on the duct give you stability forward/backwards and left/right.

I look forward to actually learning how they did it. It certainly looks cool.

0 https://en.wikipedia.org/wiki/Coaxial_rotors

Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#23

Post by api_or_ipa »

knob wrote: post #16

Throwing my idea out there: What if the to propellers are synched. Depending on desired direction, they are "un-synched" ever so slightly. This causes additional thrust on one side of the "duct".

I believe varying the speeds of the props will only give you yaw right/left. In one of the shots in the video you can see it moving sideways.

Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#25

Post by utopcell »

hedgehog wrote: post #11
sterlind wrote: post #4

Perhaps the attitude of each fan blade rotates independently. To angle the drone, say, forwards, the fan blades might angle flat when they're at the forward position, every cycle, and angle tilted at the backwards position? Seems expensive and tricky though.

"An Underactuated Propeller for Attitude Control in Micro Air Vehicles" Paper is not free but video conveys the idea well: https://www.youtube.com/watch?v=KZe7l5_LfoA Likely with clever two-material molding you could do away with the hinge and it would look similar to the prototype shown in the article.

semanticscholar link: https://pdfs.semanticscholar.org/99f8/063247da7d87de2b9d61c6...

Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#28

Post by crocal »

foota wrote: post #7

Could you flex the shape of the inner donut somehow to change the vortex?

Yes. There is this company [1] trying to use a similar concept (ejectors) to build a « motorbike hovercraft ». I haven’t heard about them for a while. They have patents on the concept [2]

[1] www.aerofex.com [2] http://www.google.ch/patents/WO2011126535A2?cl=en

EDIT: link to patent.

Re: Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone

#29

Post by taneq »

api_or_ipa wrote: post #22

Very interesting. I wondered when someone would try to mesh coaxial rotors [0] with quadcopter use cases. To make a real co-axial vehicle, you'll need to handle changes in the 3 translational axes (forward/backward, strafe left/right and up/down) as well as the rotational axes. Despite being a complicated movement, it's pretty well understood and Kamov has been making coaxial helicopters for many years. My best guess…

You only need four degrees of freedom to control an air vehicle in gravity (upward thrust and roll/pitch/yaw). You could still use internal ducting (as you suggest) to do that, but it'd probably be easier and more effective to have little flaps that deploy into the airstream under the rotors to divert the airflow.
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