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Stupid Question
  • nachosgrande
    Hi All,

    I have perfectly balanced my 3 axis gimbal, it holds in any position I place it without power. The calibration was also successful. However, when I power on the motors, every axis goes about 20 degrees askew and locks into that position. No matter how I orient it the motors hold this position. This is regardless of a power of 25 or 255. The PID settings are at zero. If I set any parameter higher than zero the entire gimbal goes into spasms. I'm sure it's just some stupid setting I'm missing, but any help would be greatly appreciated.

    Thanks in advance,
  • Garug
    Newer mind how it works at zero PID settings, do the complete tuning http://www.basecamelectronics.com/company/blog/show/?newsid=69
  • nachosgrande
    Thanks for the response Garug, but I have attempted the complete tuning, and I can't even really begin because step one assumes the motors powered on doesn't throw everything out of whack.
  • Garug
    I do not see that mentioned, but in any case newer mind how the gimbal is working before tuned. But to start you need to ensure all this is done.

    Before starting to configure P, I, D check mechanical and electrical parts of rigs.

    Make sure that there is no backlash in the rig and all nodes are firmly fixed, all screws are tightened.
    If construction of the rig is not stiff enough that it may cause complication of the rig configuration.
    Make sure that there is no friction in the bearings and no resistance for free rotation.
    The wires are flexible enough and do not prevent the free rotation of all axes.
    The camera is firmly fixed.
    The system is balanced in all axes.
    IMU orientation was configured right and all the necessary calibrations were done.
    Battery is charged above its average value.
    All electrical connections provide reliable contact.

    Note: some 32 bit boards have Pitch and Roll wrongly labeled on the board. Make sure you connect the motors according the drawings not according the board labelling.
  • nachosgrande
    Thanks again. All mechanical and electrical are in place, but I still can't get it to work properly. Any other help would be appreciated.
  • nachosgrande
    I should have mentioned this earlier, but the biggest issue is it simply doesn't return to level when the motors are turned on, it just hangs where I put it. It's almost as if the firmware doesn't know that keeping it level is what it's supposed to do. That's why I think I have some simple setting incorrect.
  • tony1483
    I got the same problem: when i powered the motors - the roll and pitch was trying to align ~20 degrees on their axis. So all i needed was to recalibrate gyro. As for spasms - the main reason would be 1) wrong acc orientation, or maybe 2) you have to invert some of your motors.
  • nachosgrande
    Thanks Tony, recalibrating the gyro didn't help though. Although I get no errors, I think there might be a hardware problem. It simply doesn't seem to understand that its purpose is to stabilize. It will not return to the calibrated position. With motors on it's just like with them off, it will hold wherever you position it.
  • Garug
    if 'I' is zero, it does that
  • nachosgrande
    I've spent hours also adjusting PID settings and it's always the same. It simply doesn't know it's supposed to return to the calibrated position. Oh well, time to return it.
  • Garug
    Are you sure you have set the IMU orientation correctly? and assigned the Pitch, Roll and Yaw axis correctly? and that motor inverted status is set correctly (use AUTO)? and that motor pole numbers are set correctly (set manually)?

    These things work, but it really requires following each step of the instructions, to get it working first time. (and that is really following, without thinking or assuming anything)

    Of-course it could be that you have malfunctioning board, IMU, Motors.....

    And some gimbal designs just are not that good and sadly many of them have no support. But I think most gimbals can be set to work, to some level at least.
  • nachosgrande
    Yes, the yaw, pitch and roll are correctly oriented, poles correct, as well as inversion. I think you're right, probably a bad part, just having trouble figuring out what part that may be because everything looks correct in the software. Probably not the motors because they can't all be bad, it's got to be the IMU or controller, however I thought I'd get errors if the sensor was bad.
  • Garug
    What does the real time graphs show. I ones had a IMU with broken accelerometers. There was actually one physically broken component on the board.
  • nachosgrande
    They seem accurate. It's a flat line for all 3 axis's when the motors are off, or when the motors are on with all PID settings at zero. When I start messing around with PID settings I get the vibrations, but they are also showing as such in the real time graph.

    By the way, thanks for all your help.
  • Garug
    do you have 32 bit board, some early 32 bit boards had Pitch and Roll motor labelling reversed on the board.
  • nachosgrande
    It's a version 1 8-bit board with a 3rd axis expansion card.
  • nachosgrande
    What would you replace first, the sensor or controller?
  • Garug
    The IMU does not cost much...
  • Garug
    Hi nachosgrande,

    I am now setting a 3 axis GoPro gimbal with BaseCam SimpleBGC 32-bit and had much of the problems you describe.

    First the gimbal is wild for 30 seconds or so and then locks to some 20 degree position. I think this is some kind of failsafe position. After power cycle it does the same again.

    The IMU works properly and it performs the motor configuration AUTO ok. (I think the SW should detect when performing the AUTO that motors are wrongly connected, but it does not)

    The solution was swapping Pitch and Roll on advanced tab. (swapping the HW connection should have same affect) Now it is ok.

    So make sure your motors are connected to right connectors, your board does not have known issue with wrong labelling and that they are correctly configured on the advanced tab.

    Hopefully this helps.
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