Replies to This Discussion

Permalink Reply by Michael Pursifull on February 11, 2012 at 8:26pm

some diagnostic suggestions:

take some closeup photos of the cabling and post on this tread

take a photo to show how the magnetometer is oriented relative to the APM and post on this tread

unplug the magnetometer and boot up again, is it faster?

Try setting "Use GDI+" in the Mission Planner settings, see if it runs faster with/without that set

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Permalink Reply by Lloyd Breckenridge on February 11, 2012 at 8:51pm

Hope this photo shows the orientation.

When the board is flipped over and screwed down it should be pins forward components down.

Like I said in the CLI compass test it is very quick and shows new headings straight away.

But when looking at the status page on the flight data screen it takes 10 or 20 seconds before the yaw value changes to reflect the new orientation.

It's like there is some dampener affecting the yaw.

Attachments:

• IMG_20120212_144315[1].jpg, 2.2 MB

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Permalink Reply by Michael Pursifull on February 11, 2012 at 9:21pm

ok, how about the other suggestions?

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Permalink Reply by Lloyd Breckenridge on February 11, 2012 at 9:25pm

This investigation started when my quad started to spin with no yaw input.

Just now I had a look at the raw sensor values.

If I just look at the gyro data then the Z gyro appears not to be working correctly.

Maybe this would cause the compass display to be slow but it certainly looks like the Z gyro range is very small compared to the other oilpan that I am testing against.

Any ideas?

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Permalink Reply by Michael Pursifull on February 11, 2012 at 9:36pm

Z should be showing gravity. What values are you getting?

Power the unit off and unplug the magnetometer. Does it work as expected? 

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Permalink Reply by Michael Pursifull on February 11, 2012 at 9:37pm

Ops, sorry, not the gyro, the Z accelerometer, that is. What is the Z gyro doing? Maybe we should focus on one issue at a time. Take a look at my first post, look at those suggestions, what do you observe?

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Permalink Reply by Lloyd Breckenridge on February 11, 2012 at 9:59pm

I have disconnected everything else and the z gyro values hardly move from 0 compared to the other gyros.
Looks like I might have a faulty board.
This may explain why the compass looks ok in the cli test but mission planner is probably teying to use z gyro to damp the compass values.

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Permalink Reply by Michael Pursifull on February 11, 2012 at 10:57pm

If you run the CLI test, do you also see very little Z gyro movement if you orient the craft such that the Z axis is horizontal/perpendicular with the force of gravity, then rotate the craft around the Z axis / yaw axis? 

Try doing this without any other sensors attached (GPS, Mag, current, etc.) Also, if you get less than expected performance, try gently flexing the IMU near the gyros... it may be that one of the gyro leads is broken/lose, and a reflow often fixes this.

Can you post some gyro output, showing yaw of the craft while it is "flat" and while it is pitched forward 90 degrees (and rotating around yaw)

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Permalink Reply by Lloyd Breckenridge on February 11, 2012 at 11:45pm

Hi again

Here is a screen capture of the CLI output.

I was shaking the board about and twisting about the z axis while this was running.

I presume Z gyro is the 3rd column and as you can see it does not move much compared to the first two columns.

I tried pressing the IMU board around when the z gyro is but it appeared to make no difference.

Thanks for all your help.

I would just like somebody to be able to confirm that the z gyro may be damping the compass reading.

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Permalink Reply by Lloyd Breckenridge on February 11, 2012 at 11:46pm

forgot to attach the screenshot

Attachments:

• badzgyro.png, 190 KB

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Permalink Reply by Michael Pursifull on February 12, 2012 at 12:30am

I'd recommend an eeprom reset, see how the numbers look afterwards. 

Permalink Reply by Lloyd Breckenridge on February 12, 2012 at 3:06am

Tried resetting and erasing but to no avail.

Thanks for your help

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