Continuous servo for roll axis

Discussion in 'Radian' started by Mike Jetter, Jan 4, 2013.

  1. Mike Jetter

    Mike Jetter New Member

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    I want to use the Radian for a 2-axis AG550 gimbal that hast two MKS BLS950 servos. The tilt servo was modified with an external pot for continuous rotation, but the roll servo is not modified (no external pot). Is it correct that also the roll servo needs continuous rotation?

    If this is the case, it seems I can either modify the BLS950 servo, or get the Freefly servos. Do you have experience with the BLS950 servo and if they work with the Radian?
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Mike:
    Good questions. I suspect these are questions best answered by JohnC (the Radian guru) or Tabb (the Cinestar and gimbal guru).

    They both check the forum on a pretty regular basis.
    Andy.
     
  3. Mike Jetter

    Mike Jetter New Member

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    Thanks Andy. I guess I have to wait until I get an answer from them.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    They're pretty good about checking the forum. If it's more than 72 hours, post to this thread again -- I'll get email when you do and can se if I can "crave audience" with JohnC or Tabb. :)

    Andy.
     
  5. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Mike,

    Yes you would need to convert the servo to continuous rotation with a resistor. I never did test the BLS950 servos but I did test a few other MKS BLS servos with not so great results.

    Before you go though the effort of modifying the servo, I suggest you try a Radian on the tilt axis and confirm those servos play nice with the Radian



    Tabb
     
  6. Mike Jetter

    Mike Jetter New Member

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    Tabb, thanks for your answer and confirming that I need continuous rotation servos for all axis. I assumed that, so I swapped the tilt and roll servo to test the roll behavior. But with the BLS950, the movements seem rough somehow and I had to turn down the gain to around 40-50 to get rid of any wobbles (when you tap the gimbal). So I ordered a FF servo and that made a real difference. The movements are much smoother now. Seems the Radian really plays best with these servos.

    My gains are still lower than 100 to avoid any oscillations. I assume this might have to do with the lower pulley ration of 2.5:1 compared to the Cinestar 4:1 ratio. Do you think changing to a bigger pulley might help?
     

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