Is there a mathematical solution for preventing fly-aways?

My understanding is that the following is what causes them:

- Accel z goes negative due to ship vibration versus an actual drop in altitude
- The ship corrects by adding power
- The added power causes a larger vibration-induced negative z
- The ship corrects the pseudo altitude drop by adding more power
- A fly away occurs

My understanding of mathematical solutions are:

- A filtered or weighted z only diminishes (does not solve) the effect.

Has anyone tried a "significant z", z / s, where s is the moving average of the variation of z?
- when the IMU isn't vibrating, s is low so the magnitude of z / s is high
   ... z is significant
   ... z can be trusted for use in altitude control
- when the IMU is vibrating,   s is high so the magnitude of z / s is low
   ... z / s has less effect
   ... and will not caused a flyaway

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btw

to study wind farm energy output and to build weather forecast I prefer satellite jet stream maps

http://squall.sfsu.edu/gif/jetstream_pac_anal_00.gif

@Bojan,

vibrations should be seperated from noise.

I have studied infrasounds generated by wind turbines world-wide.
Wind turbine either generates noise, which can be heard and generates infrasonic vibrations, which can be detected with seismographs (highly sensitive accelerometers) kilometres away from a wind turbine, since infrasonic vibrations are transmitted through the ground kilometres away.

So airframe vibrations can be sensed with accelerometers and data can be saved.

Old school Wind Farm Syndrome researchers studied noise only with microphones, in a home.
Moddern school Wind Farm Syndrome researchers study infrasonic vibrations transmitted through the ground using highly sensitive seismographs
since infrasonic vibrations, infrasounds cannot be heard but can be sensed by humans since their frequency band matches band of brain waves 5Hz-40Hz

So to detect airframe resonant frequencies I use 3+3 axis accelerometer sensors attached to the airframe or apply more advanced tools.

That the kit of the question, all for our birds better work is welcome but the most important thing for me is to have some ways to recover control, I read many Naza fly away and have a friend that lost a professional expensive equipment into the sea with a Naza not responding but I don't listen the same with ardu, I had some crashes but I had the chance to recover, only my mistakes not be so quick to do it; fpv, simple mode and pos hold save my copter in most cases because always respond in stab ................just now ;)  (I touch wood).

I understand that here the copter respond to change mode but it was too high to orient the ship, that violent reactions are really horrible and if exist the possibility to avoid is great, Forrest proposal sounds interesting perhaps Randy have the answer if it is possible to do it.

'Drone Fly-away Syndrome Pills'.  Haha, thanks very much for brightening up my evening.  Your deranged drivel gets better by the day.

Lightweight drones fly just fine in the wind:

http://diydrones.com/profiles/blogs/extreme-arducoptering

I do hobby/research flights in my lightweight drone almost exclusively in reasonably high winds (coastal northern europe) and wind hasn't caused a single crash in over 100 flights mostly at maximum legal altitude - I just allow a large takeoff/landing area and make sure nobody is anywhere near it during takeoff and landing - sensible safety precautions.  Drones (I assume you mean quad like drones) aren't like kites.. kites are like kites.. drones are like.. drones.

Last week you were obsessed with magic vibrating tables, this week it's the wind.  What are you cooking up for next week?

Fnoop: figure that video was with apm and an old firm ;)

Darius: did you fly anymore thing than a solar Kite? why don't you open your oun posts instead to continuously take others post out of topic and loose the main thread?

Dear @Cala,

Drone Fly-Away Syndrome  closed

drone fly-away syndrome pills developed

problem closed.

IMU1 + IMU2 don't work properly in tandem with EKF

some guys advised to switch IMU2 off.

Drone Fly-away Syndrome cases can be studied on the ground

at my FabLab

Wind tunnel + vibrating table + power fan

Thank you Cala and wish you a nice day.

thats it fnoop. totally agree. whats next. 

As long has you have a FC that accepts inputs and runs proper code (like pure gyro mode - without accelerometer trashing a not needed horizon) and as long as you have a pilot that can fly RC you will have no flyaways at all. If RC contact breaks do Barometer autoland (with drift) or shut down motors so no flyaway in that case as well. It can't get any simpler that this. Acc-Z jumbo-mumbo will take you nowhere. If you blame all flyaways on vibration alone you will first have to have a specific onboard sensor that just picks up vibration (maybe a little piezo-plate?) and is not disturbed by accelerations. Just my point of view.

I totally agree with you. On top of that in this thread there are alot of mixed causes of fly aways and not a proper definition of this term. And on top of that that, i personally have never experience any fly aways and instead of asking people like me; well how did you manage to build a quad that has never had a fly away, alot of the 'investigators' here are making an issue out of no issues... 

Totally agree with you.  There should be a law against autopilots that do not have the option for pure rate control and direct pilot input.

correct.

bad alt-hold auto corrections over power all stick inputs (full down doesn't do anything) ... until you hit the switch that takes you out of the elevation hold subroutine. but by then, you've lost visual of your ship's attitude (can't tell front/back, up or down)

so bringing it back under control manually is luck. RTL isn't an option either because that invokes the evil elevation hold subroutine.

with my ship, as it was switched to stabilize, it did two flips at about 100m up (only verified by the log) over a wooded area where it would have been impossible to find if it dropped. it was luck to steer the dot in the sky over my open orchard and then drop it quickly ... oh ... and a side note, the high powered fly-away, usually runs the juice out of your battery so you don't have much time left to recover the craft.

@Crashpilot1000

Although I agree that the pilot can prevent flyaway, however, as the UAV progresses and automous flying becomes a norm, the UAV must have the self-correcting functions in place in case of component failure.. my 0.02.

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