Return of the uncontrolled rotation on liftoff
Having successfully reflashed the escs ( much smoother by the way) the original problem which put me on this path remains. Basically, As i lift off, the quad spins and as soon as it makes one or two hops, it seems to jar its brain and then flies in a directed and far more oriented manner that resembles controllable. What could this be?
Setup: Stock everything with 4-12 x 3.8
APM 2
Also I seem to get caught in a loop with the newer planner when trying to graph, as the connection demands the mavlink version 1 despite it being the 1.0 version already and cannot create a graph. Any thoughts?
tLogs are attached if thats helpful
TIA Bart
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2012-06-25 01-21-45.tlog, 51 KB -
2012-06-25 01-21-45.rlog, 22 KB
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Replies to This Discussion
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DeveloperPermalink Reply by jasonshort on -
I quad with a crooked motor will Yaw uncontrollably.
Jason
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Permalink Reply by Bart Mowrey on -
Hi guys...would that not be visually apparent? how much would be enough to cause it do you think? And why would it suddenly perform better after bouncing off the ground? I realize the apm accounts for things, but wouldnt it do it more gradually?
As far as weight distribution, nothing is really off from stock save for the receiver which only weighs 1.3 grams.
Would it help to have a video or pictures?
Bart
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DeveloperPermalink Reply by R_Lefebvre on -
Well, it does correct it gradually, it might just have taken a bit of time (bounces...) to do it? It's just my guess, without having any logs.
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Permalink Reply by Dan Gray on -
One thing I'm learning about is how the motor and battery cables can affect the magnetic sensor, which is on the GPS daughter board on the APM2.
Make sure your power wires stay as far away from the mag chip as you possibly can.
Dan
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Permalink Reply by Bart Mowrey on
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Hi Dan- I think this is one thing i did well at as the wires are around 1" away at their closest point, which seems as though it would be an acceptable distance. What sort of tolerances helped you?
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DeveloperPermalink Reply by R_Lefebvre on -
My wires are about 12" away at their closest. ;)
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Permalink Reply by Dan Gray on
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Well, I'm not sure. I'm designing an isolated voltage/current board, and right now, it mounts underneath the APM2. The currrent portion of the board is 1.5" away from the magnetic chip, but I won't know until I get the new boards back and try it if this is a factor. On my first prototype, it isn't mounted underneath the APM2 and it's about 3 inches away, and I'm running 20 amps at hover, and it seems to be ok.
Dan
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Permalink Reply by Bart Mowrey on
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i suppose i shouldve elaborated that my distro board and frame is stock and about 1" from the APM as it is mounted on nylon standoffs and secured with zipties. This is an additional half inch above stock actually. Im wondering if theres an advantage of building a very fine faraday cage around it, maybe it could help with EMFs? Then again maybe thats stupid as it would block mag readings.
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DeveloperPermalink Reply by R_Lefebvre on -
Faraday cage won't block mag readings, and also won't block the magnetic field much at all. A solid aluminum shield can block some of the rapidly rotating magnetic field, but that is not the field that is causing the problem with the Mag. It's mostly the static, or slowly moving field, neither of which are blocked by Aluminum. Only MuMetal or other types of magnetic shielding can block the static field, but then they also block the earth's magnetic field... The only thing that seems to work at this point is distance. Distance, and minimizing the magnetic field generation. To do that, you need to keep all the +/- wires as close to eachother as you can, and twist them if possible.
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Permalink Reply by Bart Mowrey on
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Wait, so my quad will be susceptible to a neutron bomb EMP? I thought i was gettin milspec gear here!
Aside from the spinning issue, Im assuming that the char output from the apm is not a result of any of EMFs as that particular issue happens when just powered by the USB bus with no battery. Ive contacted support and have yet to hear a response on that front. I will attempt to get a flight in a little later today and post the logs you requested. Incidentally, it appeared that PIDs were enabled already (2.6) though ATT did not appear to be an option that i could see.
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Permalink Reply by Bart Mowrey on
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I ran through about 10 mins of liftoffs and spins. Hope these are the correct logs, as the gpx files held virually nothing other than a header declaration.
- Attachments:
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2012-06-28 13-45-20.rlog, 432 KB
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2012-06-28 13-45-20.tlog, 555 KB
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Permalink Reply by Cliff-E on -
Crazy question, but have you flown (i.e. just hover 2-3feet) with no GPS connected and compass disabled?
If it yaws under that condition on take off only--you have a frame issue. On that scenario, it's remotely possible an ESC is having trouble polling at 490Hz (if using a non-common ESC) at startup, but that's like a 1% chance. If it continues to yaw after takeoff (hover), then it's PIDs.
You have to run w/o GPS and compass to verify it's not PIDs or frame, then you can look at EMI interference with the compass, GPS, declination issues and such.
My Y6 had a bent arm--about 1^ from its designed center and doesn't yaw on takeoff when compass/GPS is hooked up.
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