Serious roll drift

Discussion in 'Radian' started by Thomas Brown, Mar 14, 2013.

  1. Thomas Brown

    Thomas Brown New Member

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    If you are having a Radian Issue please read the following first so that we can help you resolve your issue efficiently:

    Aircraft Type: Hexacopter - WKM
    Gimbal Type: AV130/360
    Radian Type ( 1, 2 , 3 axis) - Radian on roll only (RSGS on tilt, pan is manual with FF servo)
    Gimbal Power source: Separate 3S lipo
    Gimbal Radio Type: Devo 10
    Radian Communication Protocol (S.Bus, PPM, PWM, Spektrum) PWM

    Connections: Change these to match your setup
    Roll Sensor:
    Port
    1. GR-24 receiver and power.
    2.
    3.
    4. To Roll Servo

    Symptoms: Generally the horizon is ok - but in certain situations it rolls quite a lot and won't correct for quite some time. The maneuver that tends to produce this the most reliably is a "fadeaway" in which I am flying away from something and the camera tracks it (several examples in the video).

    On the ground without a camera I can put a level on the tray and turn the hex every which way and the level will be great. Up in the air something happens and the horizon goes awry from time to time. The camera is mounted quite firmly, so I don't believe it is the camera tilting. And the horizon generally corrects itself once a pan is put into motion.

    Steps taken to resolve: I have leveled it with the software ad nauseum until it is absolutely perfect on the ground. I'm considering trying to hook up roll to the radio so we can adjust it on the fly if it goes crazy.


    Video of problem (this one is critical! If you can give us a good iPhone video with audio explaining what you are looking at we can usually resolve the problem very quickly. Please tell us what is going on in the video and at what time the issue happens.)

    Please also do the following:
    a. With the gimbal powered off, connect up the USB and adapter from your PC to the Radian sensor to which you have the receiver connected.
    b. Power on the gimbal and sensors with the transmitter set to the Off mode for the Radian sensors. - I don't have the mode switch set up - no real need - I hope this isn't a problem.
    c. Use the Radian software, connect the Radian cable to the Radian sensor connected to your receiver.
    d. Click on the Connect button to connect to the Radian sensor, and check you have a connection.
    e. Click on the Read button.
    f. Take a screen shot of the Diagnostic and Configuration windows and post it to this thread with your response to Question 1 above.
    g. Then connect up to the other two Radian sensors in turn, do a Read, and take a screen shot of the Diagnostic Window and Configuration Window and post those screen shots too.





    Media:

    Video showing roll issues:
    https://www.dropbox.com/s/up25ozn39ec6omx/Radian roll.mp4?n=17894072

    Final video showing what we ended up with on the same shoot - I think this shows that we have it leveled right, because generally the horizons are good, sometimes they just go haywire:


    A couple of pics - one of the setup and one of the computer screen with Radian powered up and level after having hit the "Read" button.
    https://www.dropbox.com/s/nobhge5uz6dcglu/20130314_133311.jpg
    https://www.dropbox.com/s/59na3w2v2v7nx3s/20130314_133257.jpg



    Any help will be appreciated!

    Thanks,

    Tom
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Tom: I believe that the approved mounting position of the Radian is at the top of the arch, closer to the center of rotation. I'm not an expert on the AV gimbals, so others may shout me down (without me being offended! :) )

    Andy.
     
  3. Thomas Brown

    Thomas Brown New Member

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    Thanks Andy. I didn't put it at the top of the arch because the top of the arch (on the outside) doesn't move with the camera. Don't you want the radian to always be moving with the camera so that once it levels itself it stops turning the servos? I think that if I mounted it on the arch it would keep trying to adjust never thinking it was correcting the roll.

    Does this sound right?

    Best,

    Tom
     
  4. Brad Meier

    Brad Meier Active Member
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    I would also guess that it's probably the Radian position. On a CS gimbal the Radian is located on the roll axis.. Or very near it. I would experiment with a few locations and see if you get different results. Maybe within the top of the arch? Or below the camera tray? But I don't recommend that without adequate ground clearance. It looks like you may not have enough room.
     
  5. Thomas Brown

    Thomas Brown New Member

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    I believe I do have room under the tray. I'll give it a shot.
     
  6. Thomas Brown

    Thomas Brown New Member

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    Well I put it directly centered under the tray. I had the exact same issues as in the video I posted above, plus the added benefit of severe jitter when looking straight down (because now the Radian is tilting whereas before it wasn't).

    Again, it was perfectly level when I set it up at home. It is balanced on pans and generally while staying in one place. But put it in steady motion and the horizon goes crazy. I could post the new vids, but they look identical to the previous ones. Another day of wasted shots. This is very frustrating.

    Does anybody see a problem with the computer screenshots I posted? Is "servo out" supposed to read 34% while the tray is level?

    Any help will be appreciated.

    Thanks,

    Tom
     
  7. Brad Meier

    Brad Meier Active Member
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    Well that was my bad Thomas. I wasn't thinking about the tray moving. Of course that wouldn't work. Like and said, I'm also not very familiar with The photo higher gimbals. As for the 34%, ill have to do some thinking. Mine on the CS gimbal are less than 5
     
  8. Gary Haynes

    Gary Haynes Administrator
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    Thomas your Roll gain seems to be awfully low. Most folks are running in the 130-150 range on a FreeFly gimbal. Might try boosting it up.
     
  9. Thomas Brown

    Thomas Brown New Member

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    No problem Brad - I was hoping it would be able to figure it out - guess not.

    Just made a discovery - I noticed that while the camera points the same direction as the hex, and the hex moves forward consistently, the left side of the horizon goes high. With the camera pointed the opposite direction and the craft going backwards, the right side of the horizon goes high. When motion stops the horizon usually corrects itself.

    Best,

    Tom
     
  10. Thomas Brown

    Thomas Brown New Member

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    I definitely think I could get away with that - but that wouldn't account for why it would hold a left-high horizon steadily for 8-10 seconds, does it? I thought that raising the gains would help it to correct in a half-second versus a whole second.

    Regardless, I'll definitely try it. I'm willing to try pretty much anything at this point.

    Thanks for the responses guys.

    Tom
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Tom: Could you post an image or two showing how you have the Radians installed, please? A wide shot and close up....

    Andy.
     
  12. Thomas Brown

    Thomas Brown New Member

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    The last link in my first post should be what you're looking for. That was the setup for the first set of videos.

    I have since moved it under the camera plate exactly on the roll axis with the same orientation - results were identical. A member named zaxis on these forums used the exact same setup in my picture with the same gimbal and said it worked perfectly.

    I don't think it is gains because when I am rolled to the left the gimbal will over stabilize to the right.

    I super glued the Radian to the gimbal to be sure it wasn't being twisted slightly in the air.

    Very confused and frustrated.

    Best,

    Tom
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Understood. Just wanted to add another pair of eyes to the current setup.
    I think you're probably getting to the point where you may have to contact the dealer from whom you bought the Radian sensor -- perhaps someone else on the forum can suggest something to try....but I'm not sure what to suggest. Sorry!

    Andy.
     
  14. Thomas Brown

    Thomas Brown New Member

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    Thanks Andy. I've contacted Quadrocopter. Hopefully they will be able to help.

    Best,

    Tom
     
  15. Thomas Brown

    Thomas Brown New Member

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    OK, one last thing - I did a bunch more bench testing tonight.

    I put the level on the camera tray and the bubble is dead even wherever I tilt the hex. As soon as put the hex into motion - i.e. walking across the room - the bubble goes to one side. When I stop the bubble centers again.

    I assume that those of you successfully using Radian are able to put your craft into steady motion and still get a level horizon, right?

    Oh, also tried upping the gains - same results.

    This is driving me nuts. I have a support ticket open with Quadrocopter, so maybe they will have some insight. At the moment this is actually worse than the RSGS I was using.

    Best,

    Tom
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Just to see if it's the Roll radian that is the issue, could you swap it out with the pan Radian and see if the problem still persists?

    Thanks
    Andy
     
  17. Thomas Brown

    Thomas Brown New Member

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    I only have Radian for roll. I don't use pan stab. Just a ff servo.
     
  18. Brad Meier

    Brad Meier Active Member
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    In the photo where you have it mounted.. is that the from of the front or back? It looks like the front. The Radian should be on the back
     
  19. Thomas Brown

    Thomas Brown New Member

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    I could try that, but I don't think it would work. For my last attempt I mounted it under the camera tray all the way to the back. Same problem.

    But here's a question. You say it should be mounted on the back - but it should still be facing the same direction as in my picture, right?
     
  20. Brad Meier

    Brad Meier Active Member
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    mounted on the back, facing the back. Just like you would mount it on a CS gimbal.
     

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