M4 ladybird troubleshooting

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M4 ladybird troubleshooting

Postby axi » Sun May 24, 2015 2:00 am

Hello,
I just finished to build my little quad using ladybird motors and frame with M4. I have done simple calibration, leveling calibration but not compass calibration, because I don't think doing it at home will get good results. To fly in manual mode with Autoquad I don't need the compass right?

I have used this ladybird file http://autoquad.org/wp-content/uploads/ ... dybird.txt with original ladybird props.

I have all controls configured, etc basic stuff done. I power the ladybird, arm, take off and I can fly, but it behaves very poorly, it oscillates too much on take off, on the air it drifts to the left ( I have checked the tare calibration, it seems ok ) constantly, when I hit throttle sometimes it makes 180 degree yaw movement.

¿Where I can start to troubleshooting? PID tuning? Quatos settings? There are too much parameters to begin with... I'm a bit overloaded.

EDIT: Yaw issues were mainly because bad lipos :? for some reason when I changed them for new ones, the issues almost stopped. Maybe they can't hold power draw, because their voltage is OK... I drained new ones until green led started blinking and it turned yaw also.. Still the drift to the left is there, and slight yaw movement exist when I do some hard throttle cut offs and hit throttle hard again.

¿What batteries are you using?
axi
 
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Re: M4 ladybird troubleshooting

Postby aBUGSworstnightmare » Sun May 24, 2015 1:59 pm

You should do the MAG calibration!
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Re: M4 ladybird troubleshooting

Postby LPR » Sun May 24, 2015 2:32 pm

I'm not sure why but yaw is a common problem with the ladybird. If a motor is not completely vertical you can have a yaw problem. Some prop sets don't have quite the same pitch on their counter clockwise and clockwise props.

Because your ladybird is both having yaw and a tilt to the left I would think that you might have one motor that is not very good but just a prop that is bent a little can cause your problem. The higher the voltage in your lipo the better the ladybird can handle an imbalance in motors or props. I use 380 mah lipos.

The parameter given for the ladybird are very good so I would say your problem is mechanical; motor, motor alignment or prop.

Larry
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Re: M4 ladybird troubleshooting

Postby Max » Sun May 24, 2015 2:54 pm

The easiest way to tune Quatos is by using proportional radio channels (knobs/sliders) to adjust them in flight. You can set these in QGC on the Radio & Controls page.

I've found some of my lighter micro builds fly better (less twitchy, more precise) when I reduce AM1 and/or AM2 (by "reduce" I mean closer to zero -- these numbers can be positive or negative, meaning e.g. -25 = 25).

Everything Larry said it also true -- one bad motor/prop can make a big effect.

If the center of gravity is a little off, that can cause drifting and instability. Check the balance before each flight until you get to know where the battery is best positioned.

With the micro quads, almost any air movement can also cause a drift (lateral or vertical). If you need a few clicks of trim to keep it steady, that's not bad.

The mag calibration does not matter for manual flight or altitude hold modes (or even for position hold that much). I've found it tricky to get a good calibration on those tiny frames anyway.

-Max
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Re: M4 ladybird troubleshooting

Postby axi » Sun May 24, 2015 5:16 pm

Thank you very much for your help guys!
I'll review all my mechanical conf, change props and see if something is misaligned, I think that can be the problem.

Max, I'm just curious, ¿why do you say calibration is bad on tiny frames? ¿what can change on tiny frame vs big frame regarding that matter?
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Re: M4 ladybird troubleshooting

Postby Max » Sun May 24, 2015 5:38 pm

I mean the compass (MAG) calibration specifically -- the motors are strong magnets and are close to the MAG sensor, your body/hands are a source of magnetism/interference and can only be so far away when holding the little thing to spin it, the battery and its (relatively) thick wires can also have an effect... etc.

The good news is that AQ barely relies on the MAG readings at all anymore, so it's not really an issue. I definitely run the calibration on my larger machines though, and then verify it -- http://autoquad.org/wiki/wiki/configuri ... -influence

-Max
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Re: M4 ladybird troubleshooting

Postby axi » Mon Jun 01, 2015 11:33 pm

After checking everything... I tried to redo the tare calibration with differente bubble leveler.
My other leveler was faulty or something and off by some degrees... pff I feel like an idiot, but finally it flies very well.

I'm thinking on doing the calibso dance, it is worth doing it on a ladybird frame? if so, what's the best method, with blueetoh? or installa some expansion board to use the sd card?

By the way, Max I'm very gratefull, you're always answering my questions very kindly, thanks!
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Re: M4 ladybird troubleshooting

Postby Max » Tue Jun 02, 2015 12:03 am

Glad to hear it, and you're welcome! A measurement device which is faulty can certainly ruin your day... :evil:

You definitely need an SD card installed when doing the Calibso. As for it being worth the time... I would guess unlikely and haven't bothered with it myself, but really the only way to tell is to try it. :) Besides just seeing if it flies better or not, you can evaluate calibration results using the live telemetry view or log files, as I described in that link above. If you save your onboard parameters to a file in QGC, that will preserve your calibration results, so you can switch back and forth w/out having to redo everything (be sure to do a "Calib. Save" after uploading calibration parameters to the AQ this way, otherwise they are only loaded to temporary memory).

Cheers,
-Max
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