Hey everyone!

I am a relative noob to the RC world, but lately I have a reason to dive in head first...

I have a small company that designs & builds various electrical / alt power gear, much of it oriented around HAM radio and portable / emergency power & communications.

We have been making progress on an R&D project that just won't die... we keep getting closer to something that might work.  ;-)

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The goal of the project:

A small, collapsible flying platform that can lift a communications antenna about 30' off of the ground and hold it fairly steady for anywhere from a few minutes to a few hours.

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The antenna is a flexible whip, about 20" long and weighing 34 grams (not pictured).

Power for the system comes from a DC source on the ground.

Control of the system is limited to throttle only.

Weight of the tether (DC power, signal for throttle, and antenna feedline) at max (30') height is 500 - 700 grams.

Weight of the air frame (motors,chassis, flight control, etc. is about 300 grams.

Currently building around Black Widow 2204 motors (with ESC built in).

Using Naze32 rev5 FC with 5030 props.

Primary construction of chassis is 3D printed ABS.

A few questions:

  Do I need to use a small buck converter to deliver 5 volts to the Naze?  Information I am finding online is not clear... remember I am not running a BEC

  What is a good way to control motor speed... use a servo tester as throttle?  A PWM speed controller? Remember this control is on the ground, hard wired up to the platform.

  Any thoughts on the Naze being able to maintain level hover despite wind or movement of the operator on the ground?  We are not running a GPS and don't want to.

Thanks in advance for your thoughts!

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Replies

  • Hi Bill.

    Interesting project.

    Your flight controller will certainly need roll and pitch input to be able to stay in the same position / or follow you without any GPS input.

    I would play with building some sort of control on the airframe thats actually operated via the tether its-self. Some ring that it passes through that activates 2 potentiometers (or rotary encoders) that output PWM that can be passed back into the flight controller to control roll and pitch. These would then actively modify the flight position back to centre when the craft drifts to the side and the tether moves the "Joystick".

    This would also work for the "Follow Me" you require as when you walk in a direction you will be activating the same control that will cause the craft to try center over the tether. Just try keep the control as near to Cg as possible to minimize the effect of the natural roll and pitch from stabilization and obviously the tether would need to be kept a little taught as the craft climbs so that it can still activate the controls.

    Just an idea.

  • Bill

    The cc3d board can have a 'allways armed' setup. But maybe you will have to re-think some things on this project. I have a few questions for you.

    Can you use an operator-quad Bluetooth link?

    Can you change all this ideas and make an arduino flight controller? 

    Would you use an arduino on the ground to control the signals and just give it an altitude input?

    Have you  a pic of the quad with the antenna mounted? 

  • Bill,

    Are you concerned at all with losses in the coax cable?  How does the weight of the coax compare to the weight of the transceiver.  I ask because you have to lift one or the other and possibly with a lower loss in signal strength with zero cable length would allow a lower power (lighter weight?) transceiver?  Maybe the tradeoff in weight would make a big enough difference to make the swap.

    Maybe vision processing could be easily used for keeping it in one spot, you could make an asymmetric, high contrast, target that could be laid on the ground.  The processor on the quad could just keep the target in the center of FOV with the same orientation. 

    No GPS coverage?  Where are you going I thought that the GPS network covered the entire earth.  Do you mean GPS-denied?

    Just some thoughts,

    wade

    • Coax losses are a concern, but they are greatly offset by the gain in antenna height.  We can use a relatively thin coax (1/8" or so).

      GPS is not an option for us... GPS is not 100% coverage, and yes, there are GPS denial circumstances to accommodate.

      • Multicopter is not fit to accomplish your task since you cannot stabilize airframe.

        Try blimp instead and use HHO generator on the ground to inflate your blimp with hydrogen.

        Blimp can be transparent for some type of camouflage if required by you.

        • A multicopter will work because we will figure out how to stabilize it.  

          Apologies for repeating myself:  a blimp is not a solution for us.  ;-)

  • Wouldnt three ten foot carbon telescopic tubes be more practical for something like this?  If assembled properly they wouldn't require any more storage space than a tethered copter.  Flight time wouldn't be an issue either.  

    • System needs to move with user, if needed, and also needs to be deploy-able at sea.

  • "Any thoughts on the Naze being able to maintain level hover despite wind or movement of the operator on the ground?  We are not running a GPS and don't want to."

    Trick is to be able to measure tension angle vector of antenna relative to drone, accelerometers in drone measure gravity vector, control software then needs to align the two vectors, and adjust magnitude through throttle to predetermind tension value.

    With vectors aligned drone attitude can be whatever it takes to compensate for wind.

  • arming can be turned off in openpilot (cc3d) per setup. i would suggest using taulabs as fw.

    and consider a barometer maybe. https://www.youtube.com/watch?v=XeyPtQ203K8

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