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Roll servo driving me crazy help please

Discussion in '3 Axis Gimbal' started by Ivan Escasan, May 12, 2013.

  1. Ivan Escasan

    Ivan Escasan New Member

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    Hello I am a newbie learning fast and I have a problem and I am looking for help.

    Here is my issue, I did as far as I know a fairly good balanced on my 3 axis gimbal, My tilit is god I did the potentiometers in the
    tilit and everything good, on the roll too and everything was fine but when I place the belt and roll it to the right or left the servo keeps going and would not go back no central position, when on its central position stays there but when a roll to left or right it just keeps going driving me and the belt crazy any ideas... I am sorry if my explanaiton was not good enough.

    Thank you everyone.
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Ivan:
    Can you post an image of the gimbal from the front, the side and the back, please? It will be much easier to check. Even better would be if you could post a private video to Vimeo or YouTube so you can show us the problem.

    Also, when you describe the problem as "when I place the belt and roll it to the right or left the servo keeps going and would not go back no central position" can you tell me whether you have the gimbal powered up -- or is this what happens without power to the servos?

    Thanks
    Andy.
     
  3. Gary Haynes

    Gary Haynes Administrator
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    Ivan what are you using to control the gimbal, Radian's or something else. If it is Radian's please fill out the Radian support form in the Radian section and copy and paste it back into your reply.
     
  4. Ivan Escasan

    Ivan Escasan New Member

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    First of all than you for your help.

    What I meant is I power up everything then I roll with my dx8 to the right and the servo does it but it doesnt stop. The servo wan to go "360" all the way so I am afraid it going to break. For example I when I tilt the servo goes up and comes back by itself when I release the elevation on my controller, but on my roll servo it has no limit it goes all the way. I tried even to place a 9% limit on my DX8.

    On the video I lowered the servo to leave the belt a little bit loose because I dont want to damage the servo or the gimbal.


    here is the video

    <iframe src="http://player.vimeo.com/video/66014454" width="500" height="281" frameborder="0" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe>


    or

    vimeo.com/66014454 password : servo
     

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  5. Ivan Escasan

    Ivan Escasan New Member

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    Hi Gary , I am not using radians at the moment they are out of my budget, maybe when I do a couple of flights I will be able to get those :) I am just using a ar8000 and my dx8, a lipo, a BEC to step down the voltage and thats it or do I need the radians haha I am lost.
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Ivan:
    Thanks for the images -- just to follow up on Gary's thought train -- so you don't have any stabilization? Usually one either uses a second (independent) Flight Control board mounted on the gimbal to control the servos, or one uses the Radians. (The Flight Control board has the capability of controlling a camera -- it's not immediately obvious, but it does!)

    From what you're saying, you are just driving the servos directly from the the AR8000, right?

    I must confess I've not seen that done before, so I'm not quite sure what the results should be. Perhaps one of the other forum members has tried this?

    Andy
     
  7. Brad Meier

    Brad Meier Active Member
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    To follow along with what Andy said, without stabilization such as the Radians or another MK FC board you have no way of keeping the roll stabilized with the horizon other than manually inputing control to the roll servo from your transmitter. Normally roll stabilization is setup to be automatic and will not exhibit the movements you are describing. You may be alone and headed down an uncharted path with your current setup. Im sure others will chime in if they've tried this.
     
  8. Tim Joy

    Tim Joy Active Member

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    Sounds like your potentiometer plug is reversed. Pay no attention to the colors. Try reversing the plug, leave the belt off and move the roll by hand. If the servo appears to go in the direction to level it, then you know it's right. If not, it's reversed.
    Since your radio has no way to slew (hold a position), it should always drive the servo back to the center position when you let go of the stick.

    I do have a little device that would allow you to slew, so that it would stop at your current angle when you let go of the stick. This wouldn't be so important for the roll, but it would be much better for the tilt.
     
  9. Ivan Escasan

    Ivan Escasan New Member

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    Andy, I tought I could after watching several tutorials from quadrocopter, I followed this turorials and they are conected to the AR8000 and thats it and this one I got it from Quadrocopter webpage.

    So what do I need Radians ? and thats it ? or do I need more stuff... This is going to be another big hit to my wallet ( credit card no more money left ). Well I am already several thousands into this so no way back. Andy can you tell me what I need, just radians or I am going to have another major hit down the road haha.

    Thank you. Which is better Radians or another flight control board ?
     
  10. Ivan Escasan

    Ivan Escasan New Member

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    Thank you but what do you mean by reversing the plug ?

    I mean I already took out the potentiometer and I level it but when it rolls to the side it just keeps going.
    The tilt is fine, when I realease the stick it goes back but on the roll it does not :(
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Aha. Now I understand -- I thought you were trying to have automatic stabilization of the gimbal -- but you just want to manually control the servos. That video was done by Cedar Beauregard -- I'm not sure when it was done, but I suspect it was quite some time ago.

    In which case, Tim's idea might help -- by reversing the plug, what Tim means is that the 3-wire plug from the potentiometer to the servo can be connected up two ways based on the shape of the plug -- so unplug it and rotate the plug around the long axis 180 degrees and plug it in again. I've not tried this, but I suspect Tim has.

    The Radians do a better job of stabilization than the Flight Control Board, but you will need to be prepared to spend the time to fine-tune their settings as the physics of the the gimbal and the camera are quite complex. So manage your expectations to include this fine-tuning.

    You will need to buy three Radians -- one for each axis, but I don't recall having to purchase anything else.

    Andy.
     

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