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. ;-)
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.
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!
Replies
but it's a waste of time to discuss your project.
This is not a project, just your idea fix.
Tethered drone is twice as expensive as free flying drone
and can crash easily, line can twist around frame and propellers
in case of side wind.
Please close this thread and visit rcgroups.com
to get ready, pretested, twisted aircraft solutions.
Darius,
Sorry you feel the time is wasted.
You said: "This is not a project, just your idea fix."
I disagree, even though I am unsure what an 'idea fix' is. It is a project, one that we have been working on for some time. I posted a pic (not a render) of the latest prototype. Perhaps you missed that in your effort to save time.
You said: "Tethered drone is twice as expensive as free flying drone"
I never mentioned a cost target. I do not know what the production cost will be yet. Perhaps it will cost twice as much. The difficulty of execution can be an indicator of market value.
You said: "...and can crash easily, line can twist around frame and propellers
in case of side wind"
That is your opinion. I am trying to solve those issues, and am looking for constructive help.
You said: "Please close this thread and visit rcgroups.com
to get ready, pretested, twisted aircraft solutions."
mmkay, I'll get right on that.
@Bill - this is a really cool project!
I suspect that using a standard flight controller might not be the best approach. The difficulty is that you have a point of constraint where the cable attaches to the 'copter and the stabilizing routines in a flight controller assume complete freedom of motion. I'm sure that at least some modification to the control algorithms would be needed since the accelerometers would behave quite differently under these conditions.
Taking a lateral approach for a moment. The problem to be solved is keeping the tether as vertical as possible with respect to the ground whilst keeping positive tension. IMHO measuring the position and tension on the tether is the sensory input needed not anything related to the coordinates or angles of the 'copter.
Practically, this would require a bunch of non-standard electronics so maybe it's not an option for you, but if you chose to use your current approach please be very careful about system stability and don't be too surprised if the 'copter flies at high speed into the floor for no apparent reason :)!
Exactly - just not sure what @Bill's electronics skills are up to. The advantage of force sensors is that you can also control the total pull to save some power.
Great feedback so far, guys... thanks.
I am unfamiliar with in-line quoting on this forum, so I will just try to address different points without citing the poster(s).
Yes, I think I need a better understanding of how FC works... arming, etc.
I really think the joystick idea is clever! But this system might be tethered to a persons belt or pack or a boat... I don't think I should limit applications by assuming the joystick would have free range of motion...
I agree with the poster suggesting a buck converter to supply 5v to the naze.... and agree it should be on the platform, not the ground.
Initial testing is telling us to expect 3-5v drop over 30 feet using 18AWG for rotor power. This is acceptable, as the ground power can be (within reason) whatever it needs to be.
I like the force - sensor idea, but not the complexity of it...
Regarding GPS, if we need it to make this thing work, I will probably kill the project.
The main thing I am trying to accomplish is to keep everything as simple as possible. Reduce failure modes. Reduce components. Reduce operator input.
We actually had a non-electronic (mechanical) attitude control in an early prototype that nearly worked... a pair of spur gears. One attached to the underside of the flight platform, the other attached to the tether. If the tether pulled one way, the spur gears reversed the motion and tilted the craft into the pull.
I guess my ignorance is showing, but I still think we are not asking for that much: hold the platform horizontal.
Thanks again, please keep brainstorming!
It will not work with a standard flight controller. For them you need to execute an arming sequence or configure an auxiliary switch. To be clear: you need more than 1 channel (servo tester or whatever sens a pwm signal).
I also suggest that you spend more time on reading how a flight controller works. Radio channel configuration and arming sequence may be of interest.
Its a great looking render without GPS you are going to need a vision based system to hold position. I think without that you are in danger of your machine driving itself into the ground when a big gust pushes it to the end of its tether.
Power and comms going up and down by cable, thats going to weigh quite a bit.
What is the weight of the coax for the antenna? Is it APRS you are trying to lift?
Using vision is a cute idea Gary, but couldn't it be much simpler by using a joystick attached to the cable so that it measures the direction of the cable pull. By reversing the control directions it could literally fly itself like an RC copter :O
Bill, in general you can find Ardupilot-Pixhawk users in this forum but I hope Naze uses 5v too, you can use a bec to power it, you need esc to control motors connected to the controller and need a gps to hold position.
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