Pan axis jitters / PWM issues

Discussion in 'Radian' started by Matt White, Sep 14, 2012.

  1. Matt White

    Matt White New Member

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    Hey all-

    Got the three axis installed last night, and both roll and tilt look good for stabilization... However, when I activate the pan axis with the switch on the tx, it starts oscillating back and forth pretty rapidly (maybe only a couple of degrees each way). It's almost like the Radian thinks the servo connected backwards somehow, like the Radian thinks it's going clockwise and it's actually doing the opposite, so it just keeps jumping back and forth... I have it connected as Pan-1, and mounted as such, so it doesn't seem like that should be it. The gimbal is a stock 3-axis cinestar with the servo in the standard place...

    Also, for some reason I'm getting some really jumpy signals out of my PWM connections... The monitor in the PC software shows the indicated PWM values jumping around a ton in both directions whenever I deflect a stick, even though I'm holding the stick steady, though offset from neutral. As a result my tilt axis is jumping around a lot and generally lags behind the commanded value from the stick. I've tried two radios from totally different manufacturers (one Spektrum DX6i, one Turnigy 9x with er9x) and gotten the same result on both...

    Going to get back on it and see if I missed anything obvious, but I just thought I'd see if anyone else has any ideas!

    Thanks!
     
  2. Daisuke Ide

    Daisuke Ide Distributor

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    Have exactly the same problem too.I am also looking for a solution.
     
  3. Howard Dapp

    Howard Dapp Active Member

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    Have you guys adjusted any parameters such as gain? Try lowering the gain settings some until the oscillations stop.
     
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  4. Matt White

    Matt White New Member

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    It's the gain on the pan unit... It defaults to 100, I had to drop it to 60 to get it to stop oscillating. The other axes run at about 110, but the pan axis is much lower. Also, you really need to hang the heli from a rope or something to tune the yaw axis, because if you arm te gimbal on the ground it will start to drift and spin. When you suspend it, it's fine...

    The issue now is that I have a little bit of a dead zone in the middle where when I disturb the heli clockwise and then reverse it, it takes about 5 degrees of rotation to reverse it. So, if you wiggle it from clockwise to counterclockwise the wiggling isn't really compensated. It's splitting hairs, and I don't expect it to be an issue on yaw, but it does it a bit on roll as well, which might show up in footage.

    Overall, though, this thing is bloody amazing!
     
  5. Howard Dapp

    Howard Dapp Active Member

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    No, It's not splitting hairs, you should be getting the exact same performance as Tabb has demonstrated in his videos. Keep at it, play with the settings more until there is no delay in compensation when disturbing the gimbal.
     
  6. Daisuke Ide

    Daisuke Ide Distributor

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    I tried to change the various parameters and SLEW GAIN, of DeadBand.
    I can not understand well but PAN control of Radian.
    PAN would begin to drift and rotate the mode with STABILIZED SLEW.
    To stop the rotation must also do stick in the opposite direction.
    You can set it up to stop the rotation of the PAN when a neutral stick?
    So far, I have experienced and DJI Z15?and HoverFly Gimbal.
    Seems clearly different PAN control of these and RADIAN?
    I wonder if there are any special settings??or Maybe my settings are wrong?
    What kind of Radian's movement is correct?
     
  7. Matt White

    Matt White New Member

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    So after switching the BEC to 6v, it seems like I'm getting more torque out of my servos, and the deadband is a bit less of an issue. Still there a bit, so will do some more trial and error to figure it out.

    The PWM is still a problem, though... I've tried the same two radios again (Spektrum DX6i with a 6200, ER9x radio with 8 channel receiver), and both times I get a ton of noise on the slew monitor in the PC software. I'll command a +50 slew on one axis, and the PC software indicates that, and then it starts to jump around, as far as -20 slew, all with the stick left static. I've seen this applied to the axis on the gimbal, with my pitch axis jumping all over the place even without moving the stick.

    It seems to work great with a Spektrum satellite receiver, but PWM seems like a no-go based on both different radi manufacturers I've tried... Not sure what else to do there, as there isn't any config to change for PWM.
     
  8. Matt White

    Matt White New Member

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    Daisuke-

    If you leave the pan stabilization on with the heli just sitting on the ground, it will eventually start to drift and spin. You can get it to stop with stick movement, but it will start again. I think that's why they recommend leaving the pan axis disabled on the ground. Once in the air (or if you hang the heli from a rope, as in the gimbal balancing videos) then it seems to work fine.

    So from what I can tell, you shouldn't worry too much about what it does on the ground, try suspending it and see what it does there.
     
  9. Daisuke Ide

    Daisuke Ide Distributor

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    Hi Matt.

    Thank you for useful advice.
    I tried hanging the Gimbal. It was as you said.
    I was impressed with the amazing.

    Thanks.
    Daisuke
     
  10. John Cunningham

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    Guys,

    Just to let you know, we have a fix for the PWM issue.

    We just need to give it some flight time to be sure all is OK then we will post a firmware update for the Radian modules.
     
  11. Daisuke Ide

    Daisuke Ide Distributor

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    JohnC.

    It's sounds good! I'd love to test it soon! !

    Thanks.
    Daisuke
     
  12. Sedric "Zellevision" Sari

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    Great. That is the same problem I had with PWM, Hade to change back to PPM but perfer PWM coz running mx20 with 2 receivers, one gr24 on the cs and gr16 on the 3-axis..
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Just out of curiosity, which controls on the MX-20 do you use for controlling the 3-Axis and the GR16?
    Also, did you have any problems binding the MX-20 to both the GR24 and the GR16? For single person operation, it sounds like a good solution.

    Thanks
    Andy
     
  14. Sedric "Zellevision" Sari

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    All 3 potis + 1 3-way switch. We normally do 2 man shows, and then ofc 2 radios, but now and then solo, and when practice its needed...
    No problem at all, just bind them both with MX-20 or MC-32... But, you only get the channels the TX can deliver... mx20 = 12.
    So I hade to reeeeeally had to think 12 times and use them all! ;)
    1-4, 8-12 at GR24 on the CS and 5-8 on the gimbal. Works perfect, but I think its easier to map channels with PWM them PPM.. I perfer chans 1-8 to CS/MK-FC and the last 4 to my gimbal...my 2 cents... But PWM gives craaaaaaaaazy noise at the radians, atleast until the fix :)
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    You managed to lift and wear an MC-32 without falling on your face? ;)
    Thanks for the information on the channel setup too!

    Andy.
     
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  16. Josh Lambeth

    Josh Lambeth Well-Known Member

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    When you say crazy noise are you seeing odd movements with the PWM setup such as your radians not compensating correctly? Im really hoping thats my issue but I can't do anything with the PPM/Spektrum till they update the software so I can use them in the beta tester configuration. I don't have any of the mounting hardware to use them in the correct locations that the software is written for. :(

    Josh
     
  17. Sedric "Zellevision" Sari

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    ;) Ure welcome... then you should see my one-man-board, 7" monitor, video rx, battery and mx20, thats overbalance :D
     
  18. Sedric "Zellevision" Sari

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    Josh, with PWM, the crazy noise is upcoming when I try to trim the roll or set the tilt from my radio. As I do it and watch the software and the gimbal, the signal goes all over the slew bar (not all the time, but very often), AND the same axis does the same crazy jumping or goes hard one way and really "hurts" the servos, as I release the potis/stop trimming, the major noise is gone but some minor is still there, both in software and on the gimbal, all axis. But when I change to PPM, no noise left. But even in PPM mode I have some jumping on the roll on the bench, but NOT in the air (!) and this could/should be a gain issue.

    For the PWM, I tryed to lower all servo settings from the TX, the limit, the travel, the speed etc, same same...
     
  19. Mark McGuire

    Mark McGuire Distributor

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    Set up a 2axis, pwm, & alls working great in auto stabilization mode, but when i try to plug the tilt into the receiver im getting noise & limited servo travel, & i have to stick the opposite way to get the tilt to stop, maybe im missing something, find the wire diagram for pwm a slight bit confusing too.. would be good to see examples of wiring with the corresponding software input channel settings. Have i got something wrong or is the coming firmware update curing this.
     
  20. Josh Lambeth

    Josh Lambeth Well-Known Member

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    This might help with the PWM wiring...



    Josh
     

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