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And a normal barometer bench check should read???

Posted by Steve Smetters on August 3, 2011 at 8:04pm

Hi all,

I am trying to diagnose an altitude hold issue where the the motors are quickly jumping faster and slower in order to maintain altitude... the quad sounds like it is chasing it's tail. A static check of the barometer on the bench using the CLI test---> altitude command shows the barometer jumping quickly anywhere from -60cm to +50cm or so passing through 0 often. Is this normal? Has anyone else checked theirs statically to see what the variance is? Thanks...

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Replies

  • Steve Smetters August 10, 2011 at 6:00pm

    yes, thanks for the reply's. Turns out the jumping motors was due to my sonar module.... I did place as shown in the wiki but am still getting some interference. Will try shielding the cable next.

  • 100KM
    u4eake August 4, 2011 at 12:59am
    If you have a sonar, make sure it's mounted well away from esc's and motors, as shown in the wiki. A noisy sonar (due to interference) typically produces a copter with hunting motors (vroem, vroem,...) In normal alt_hold in quiet weather you almost shouldn't hear the motors change rpm.
  • 3D Robotics
    Chris Anderson August 3, 2011 at 9:08pm

    That sounds pretty normal for the bench. Here's some sample data from a couple boards on the bench:

     

    Alt: -2.10m, Raw: 97376
    Alt: -2.01m, Raw: 97375
    Alt: -1.92m, Raw: 97374
    Alt: -2.01m, Raw: 97375
    Alt: -2.01m, Raw: 97375
    Alt: -2.10m, Raw: 97376
    Alt: -1.92m, Raw: 97374
    Alt: -1.83m, Raw: 97373
    Alt: -2.18m, Raw: 97377
    Alt: -2.36m, Raw: 97379
    Alt: -2.36m, Raw: 97379
    Alt: -2.36m, Raw: 97379
    Alt: -2.36m, Raw: 97379
    Alt: -2.53m, Raw: 97381
    Alt: -2.53m, Raw: 97381
    Alt: -2.36m, Raw: 97379
    Alt: -2.45m, Raw: 97380
    Alt: -2.45m, Raw: 97380
    Alt: -2.36m, Raw: 97379
    Alt: -2.18m, Raw: 97377
    Alt: -2.18m, Raw: 97377
    Alt: -2.01m, Raw: 97375
    Alt: -1.92m, Raw: 97374
    Alt: -1.92m, Raw: 97374
    Alt: -2.01m, Raw: 97375

     

    Here's another board:

     

    Alt: -0.52m, Raw: 97340
    Alt: -0.52m, Raw: 97340
    Alt: -0.52m, Raw: 97340
    Alt: -0.52m, Raw: 97340
    Alt: -0.52m, Raw: 97340
    Alt: -0.52m, Raw: 97340
    Alt: -0.43m, Raw: 97339
    Alt: -0.35m, Raw: 97338
    Alt: -0.35m, Raw: 97338
    Alt: -0.17m, Raw: 97336
    Alt: -0.08m, Raw: 97335
    Alt: -0.08m, Raw: 97335
    Alt: -0.08m, Raw: 97335
    Alt: -0.17m, Raw: 97336
    Alt: -0.17m, Raw: 97336
    Alt: -0.35m, Raw: 97338
    Alt: -0.17m, Raw: 97336
    Alt: 0.00m, Raw: 97334
    Alt: 0.00m, Raw: 97334
    Alt: 0.00m, Raw: 97334
    Alt: -0.08m, Raw: 97335
    Alt: -0.17m, Raw: 97336
    Alt: -0.17m, Raw: 97336
    Alt: -0.35m, Raw: 97338
    Alt: -0.26m, Raw: 97337
    Alt: -0.17m, Raw: 97336
    Alt: -0.17m, Raw: 97336

  • Developer
    Jason Short August 3, 2011 at 9:07pm
    That's about right.
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