Your Radian gains?

Discussion in 'Radian' started by Brad Meier, Sep 19, 2012.

  1. Brad Meier

    Brad Meier Active Member
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    Pete, after reassembling my gimbal this morning I also found that with the radians off, applying pressure and releasing on the bottom of the tilt arm will produce an oscillation in the tilt axis and the same with rotation but not as much. I however do not have flex in any part of my gimbal. It seems to be a harmonic. I'm going to try moving the balance around get off that harmonic.
     
  2. DooZee Aerial - Pete

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    Im not saying its a massive amount of flex.. but its there.. Enough at least to be a pain..
    If you look at other gimbals available (And this is where i get shot) for example for the DJI s800, its Solid. So it doesnt have the same issue.
    Ill keep pluging away, and hopefully will have Positive news in the next few days.
     
  3. Josh Lambeth

    Josh Lambeth Well-Known Member

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  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Pete:
    Are you seeing this vibration while the gimbal is powered up? (I'm not sure grabbing your gimbals is legal in Oregon? <evil grin>)
    Also, are you using the Radian sensors to stabilize or the MK FC board?

    If it's the Radians, is there any chance that you have the gains set too high. If I set the gains just a teensy bit too high, it makes the camera vibrate if it thump it gently....the response from the Radians with the correct gains should be quite "dead."

    Hope this helps
    Andy
     
  5. Brad Meier

    Brad Meier Active Member
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    I just did a flight after rebalancing and adjusting/ modding my gimbal. I did it all with the radians off and got smooth video. There are only movements of the copter but no hard jitters or vibration. So.. Basically nothing new. This was using small o rings and joes zip tie mod. The good news is with the gimbal mounted this rigid to the copter I hope to be able to have the gains set higher than 70! Ha
     
  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Try 150 on Roll and tilt. See what happens. If you get really fast jitter knock them down to 120. Then up to 140, then 130, ect. Obviously your numbers might vary a bit but good starting point.

    Josh
     
  7. DooZee Aerial - Pete

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    Andy,

    The "Wobble", "Vibration" is with the gimbal powered down.. Its a mechanical wobble that im trying to get rid of.
    Ill try to post a video of what i mean..
    but its only apparant on video when using the heavier camera.
    Ive just done the "Cable Tie" mod, so will be testing that this arvo.. and ive tried to remove all the excess weight from the camera mount i can, hopefuly to, if nothing else, make the gimbals life easier.
     
  8. Wolfgang Armin

    Wolfgang Armin Active Member

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    Today I changed my pan-servo. I had purchased a spare-servo and decided to give it a try. To my surprise, it seems that the "stuttering" is gone. Thanks for tip, Andy (few pages before).

    The new servo is a black one, while the one delivered with the gimbal was gold. Is there generally any difference between these?

    I´ll do some more tests tomorrow if the fog clears up and try to increase the pan-gain.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I've told you before, Wolgang, if it works it's my idea. If it doesn't then it was your idea. <evil grin>

    Tabb answered this somewhere else on the forum, but to save either of us searching, let me tell you the secret answer: The difference between the gold and the black servos is the color (aka colour). :rolleyes: Keep this to yourselves, folks...

    Seriously, Wolfgang, thanks for the feedback. I wonder whether the "bad" servo has more play in the gearing on top of the servo? Or was the small pulley creating "play" between the servo and the big pulley?

    Andy.
     
  10. Colin Snow

    Colin Snow Active Member

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    I installed a Radian on roll axis yesterday at a gain of 130%. I had two sucessful flights and level horizons. However, on the third flight I encountered a lot of oscillation - so much so that the gimbal was "stuck" in oscillation even after landing. When I got it back on the bench I I looked to see if it lost the setting but it hadnt. So I tried a setting of 100 and it still oscillated. So I took it down to 70%. That stopped it, but it seems sluggish now. What gives? Why would this happen? All my boot-ups are still and it does have the latest firmware.
    Anyone else experience this?
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That is very disconcerting to hear about Colin. Firstly because 130% does not seem excessively high, and secondly because the problem is not deterministic -- you would expect consistent behavior at any given gain setting and that does not seem to be the case here.

    The fact that it was still oscillating after landing is curious -- do you have a Mode control and was it switched to off, or was this oscillation happening in Fixed Stabilized?

    I'm not sure what you meant by: "All my boot-ups are still...." Could you clarify that?

    Thanks
    Andy
     
  12. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Colin,
    What version of Firmware are you using? Sounds like it could be the earlier version where the Roll would sometimes jitter around? Could be wrong but it's a guess. If you haven't already, update your firmware to the latest (1.02) and see if that helps.

    Also wondering if maybe the voltage dropped too low and it reset the unit while in air?

    Josh
     
  13. Colin Snow

    Colin Snow Active Member

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    Josh - I am using 1.02. Firmware upgrade was the first thing I did before mount and configuraton. I thought the problem was a voltage drop too and that it reset itself in the air but when I tested on the bench post-flight it was with a fresh battery. At that point I purposely reset to default and then set it to 130 and it still oscillated. I then set gain to 100 tested and then to 70 which is where its at now - albeit sluggish in response.

    Andy - Still = no movement on the Radian.
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Colin: Oh....sorry I misread "still" as meaning "continuing" -- hence the question still continuing to be what? :)
    Britspeak strikes again.

    So when you landed and it was still oscillating, what mode setting were you in, please?

    That said, it sounds the sensor may have failed -- the probative fact being that it was working fine in the early part of the flight and its behavior changed dramatically, suddenly, and apparently irreversibly, in flight.

    Thanks
    Andy
     
  15. Colin Snow

    Colin Snow Active Member

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    Hi Andy - Mode was default / Roll1. Well if push comes to shove I can test your hardware theory because I have a second unit. At the time I purchased you couldnt buy just one unit and get the connector separate (yes I spent $700 when I really only needed to spend $350). I plan to flight test at the 70% on Monday but it will be a blind test because as you know the FFS HDMI converter overheats and the image goes black.

    BTW - in case it matters I have power coming in port 1 and the servo on port 4. See "Scotty, I need power" for details on my wiring set up.
     
  16. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Colin,

    Please confirm that everything is mechanically tight. An oscillation that starts randomly like this points to a mechanical change. Please confirm the large roll pulley it tight (2 button head screws hold that to the carbon piece), the servo pulley is tight, belt is tight etc.

    I doubt the sensor has failed, double check the mechanics first.

    Tabb
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Yeah, Colin, I was too quick to use the "failed" word -- I was wondering what else might cause the oscillation so Tabb's got a valid point. I got oscillation in pan once when the belt was not quite tight enough. Let us know if you find something that has worked loose and shifted along a boom or rotated.

    Are you also providing a control signal on port 1? If you're only providing power (because you're using a Spektrum satellite receiver, for example), you might want to use a different port (the power and ground pins are all ganged together). I seem to recall a post from someone (perhaps Tabb), where the poster mentioned that there might the risk of electrical noise on the floating input on port 1.

    Hope this helps.
    Andy.
     
  18. Colin Snow

    Colin Snow Active Member

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    Tabb - Thanks for your reply. Will check mechanics and report back.

    Andy - No rx signal; just plugging in the three pin connector from the Castle BEC. That said it does have a "signal" wire and I cant tell what is the purpose of the wire.

    Tabb - Should I move power to another port? Should I clip the BEC signal wire? If so, what do I lose?

    Colin
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hmm. The odds are the "signal" wire from the BEC is grounded, but just to be sure, I'd move power to port 3. I don't think this is the actual cause of the problem, but it's one less thing to worry about.

    Andy.
     
  20. Colin Snow

    Colin Snow Active Member

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    Tabb - I confirmed that everything was mechanically tight. I moved power to port 3 and configured at 100% gain. First test flight with this set-up didn't produce any oscillations that I could see on recorded video. However, I did not have power to transmitter or HDMI converter connected. I plan to do more test flights adding back the Tx and Conv which have separate main power taps.

    Colin
     

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