Replies to This Discussion

Permalink Reply by heikki.tukiainen on July 31, 2012 at 12:13pm

Attached is a gopro video of the wobble:

http://www.youtube.com/watch?v=I5VSN_n__gQ&feature=youtu.be

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Permalink Reply by Mike Boland on July 31, 2012 at 12:37pm

Just considering the simplest first, Is the frame balanced?

If the motor is having to do more work than the rest it would explain it.

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DeveloperPermalink Reply by jasonshort on July 31, 2012 at 1:59pm

The ESC heat is probably the BEC. The motor heat is probably a bearing or shaft that is sticking out the bottom, hitting the frame arm.

Jason

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Permalink Reply by heikki.tukiainen on July 31, 2012 at 10:17pm

Thanks Jason & Mike!

Mike: Yes need to check the balance. With eye all is linear & balanced. Only the BEC is on "heating side" of the frame - but the front motor is ok. BEC is quite light.

Is there an offsett in APM2.0 settings i.e. a compensation for non-central position of APM. Need to check that one as well. Perhaps I have just the offset wrong and APM is having hard time with offset vs. sensor data, causing it to wobble.

I am thinking this:

Jason:

BEC: a separate bec. All escs have the red line cut off.

Shaft: I have checked this - even made the hole for the shaft bigger. Should be not an issue.

I have tired a alot & a little desperate- it is so close to a perfect flight!
Thanks for your help!

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Permalink Reply by heikki.tukiainen on August 1, 2012 at 8:07am

Continuing my search for a wobblefree quad.

See below logs of my test flight:

Red = yaw in --> I have full right and left yaw in

My observations:

right yaw goes nicely. Smooth motor curves.

Left yaw shows zig-zag = wobble. Always few zigzags. In both motor 3 &4.

The motor that gets heated is number 4. That motor for some odd reason is always driven higher that e.g., counter part motor3. --> there is some inbalance in the frame / motors / props.

The wobbling direction requires much more difference between motors 3&4 vs. 1&2 --> I would assume this means in build right way in the frame which is compencated by motors 3&4 and escpecially number 4
My conclusion:

Need to find a way to get load of motor 4 down to same level as others. That might be the root cause of this all.

Need to look for the root cause for right yaw that is compenzated by motors 3&4,

And the search continues! :-)

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Permalink Reply by heikki.tukiainen on August 1, 2012 at 8:39am

attached picture of the frame:

The rx is bit on backside othewise it looks balanced.

Motor tilting needs to be checked. My bet is that one unalighed motor causes inbuild right yaw - but it is not easy to find.

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Permalink Reply by m00se on August 6, 2012 at 12:56pm

have you checked things like cable length on the esc?

I have put the Rx on the bec of one ESC and the APM on the BEC of another to try and distribute power consumption a bit, although i dont think the ma pulled by either is an issue,

have you balanced the props? try moving the prop on the hot motor to the other side, maybe vibration is making the motor drop in efficiency and have to spin faster to maintain level,

I generally find my front motor to get a bit hotter than the rest, i blame it on the fact its a cheap chinease piece of crap

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