Tilt axis problem - only moves in one direction

Discussion in 'Radian' started by Theo Amer, Apr 7, 2013.

  1. Theo Amer

    Theo Amer New Member

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    Aircraft Type: Cinestar 8
    Gimbal Type: Cinestar 3-axis

    Radian Type ( 1, 2 , 3 axis) 3 axis
    Gimbal Power source: 11.1v
    Gimbal Radio Type: Spektrum DX8
    Radian Communication Protocol (S.Bus, PPM, PWM, Spektrum): Spektrum

    Connections: Change these to match your setup
    Roll Sensor:
    Port
    1. Pan sensor
    2.
    3. To Tilt sensor
    4. To Roll servo

    Tilt Sensor:
    Port
    1. Roll sensor
    2.
    3.
    4. Tilt servo

    Pan Sensor:
    Port
    1.
    2. Battery
    3. Roll sensor
    4. Pan servo

    The port on the bottom of the Pan sensor is connected to the Spektrum receiver

    Symptoms:

    When the gimbal is powered up the roll and pan axis seem to work OK. But the tilt axis is having problems.

    I have no control of the tilt axis through the transmitter (radio) - if I move the tilt control the tilt axis does not respond. However it will often suddenly point the camera at the sky without any input from the transmitter.

    It also appears to try to stabilise the camera tilt in only one direction - in that it will tilt the camera up if the heliocpter tilts forward, but will not tilt the camera down when the helicopter tilts back (see my video). Leaving the camera pointing at the sky.

    Everything worked fine for the first flight, but halfway through the second flight the camera suddenly pointed at the sky and the tilt axis stopped working - we hadn't made any configuration changes.

    Steps taken to resolve:

    I have checked the Radian settings through the Radian USB tool. The tool can see the tilt control input from the transmitter, and the channel appears correctly assigned.

    I have also re-installed the latest firmware 1.03 on the tilt radian, and reset to default settings.

    None of this has had any effect.

    I've attached a video of the problem and screen shots of each of the Radian's settings.

    Theo

    Ps. Tried to upload video of my problem but browser told me it was too large. Is there a maximum file size for upload on the forum?

    Pan-1.JPG Roll-1.JPG Tilt-1.JPG
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Theo:

    Bonus points for such a complete problem report! :)

    Can you confirm that when you operate Channel 2 on the Spektrum transmitter that you see the "Mode" slider moving horizontally?
    In all the images above, you can see that the Radians are in the Off mode.

    We need to establish that you actually do have mode control from the transmitter.

    Also note the check box "off unless using Spektrum" is unchecked. Please try checking that for the Pan sensor. The other Radians talk Sbus between themselves (which is why you see the "SBUS Valid" check box on roll and tilt).

    As to posting videos: there is a 2MB limit for upload, so what folks typically do is upload the video to Vimeo or YouTube and insert a link by clicking on the little projector screen below and to the right of the smiley face in the message preparation window.

    Let me know what happens when you do the above, please.
    Andy.
     
  3. Theo Amer

    Theo Amer New Member

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    Thanks Andy :)

    When I operate Channel 2 on the Spektrum transmitter with the Radians in the ON mode (Radian tool connected to the Tilt Radian) I see the "Slew" slider moving left and right - but the "Mode" slider doesn't move. It stays at 85%.

    I see the same thing on the Pan axis - the "Slew" slider moves when I operate Channel 4, but the "Mode" slider stays at 85%.

    I've checked the box "off unless using Spektrum" on the Pan axis - but the problem still persists.

    Here's the video I made yesterday:

    Theo
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Theo:
    OK. Well the first problem we need to solve is why the Mode slider is not changing. That's more likely to be in the Spektrum transmitter.
    Can you get into the DX8's Monitor window and see whether Channel 5 is changing in response to the appropriate switch on the Transmitter?

    If it is, then can you double check, by plugging the Radian PC link cable into the Pan servo (which has the Spektrum receiver plugged into it), Connect, and then see if there is any Mode control when you operate the switch on the Tx that controls channel 5.

    Let me know what you find.
    Andy.
     
  5. Theo Amer

    Theo Amer New Member

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    Hi Andy,

    The DX8 monitor window shows Channel 5 changing in response to the correct switch on the transmitter, as does the 'Input Channel Monitor' on the Radian PC tool.

    With the USB cable plugged in to the Pan Radian the Mode slider sits at -85% when the Channel 5 switch is in the OFF position. When I turn the switch to the ON position it moves to +85%.

    However when I move Channel 4 - the Slew slider moves, but the Mode slider stays at 85%.

    The same thing happens with the Slew and Mode sliders when I use the tool to look at the Tilt Radian.

    Theo
     
  6. Brad Meier

    Brad Meier Active Member
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    The mode slider shouldn't move with channel 2 or 4 inputs from you. The mode only moves with your channel 5 switch. So -85 is correct for "off" and +85 is correct for "on". I don't see anything there that could be causing this but hey, I'm on my phone on a plane over Kansas and I've been known to be wrong before.

    One thing I noticed is your servo out sliders have fairly high numbers for being stationary.

    One suggestion I have would be to try and swap the Tilt Radian for the Roll Radian and see if the problem stays with that Radian.
     
  7. Theo Amer

    Theo Amer New Member

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    I've swapped the Tilt and Roll Radians around - and re-assigned them to their new axes.

    The problem with the Tilt axis still exists - it hasn't moved to the Roll axis. The tilt axis still pitches up only, and not down - it still doesn't respond to inputs from Channel 2.

    Does that suggests the problem may not be with the Radians.

    Could it be a servo issue? I've noticed that the Tilt servo makes a very subtle grinding noise at some points of travel when I move the tilt axis manually. I don't get that noise from the other servos.

    Theo
     
  8. Brad Meier

    Brad Meier Active Member
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    We are getting there Theo. Thanks for the quick update. I think we can rule out it being an issue with the Radians. I'm not sure why this would help but try re-binding your satellite receiver to the transmitter. If your servo sounds bad then it's probably bad. Is your camera balanced in the tilt axis as per Tabbs videos? That could've put strain on the servo. Did you have any hard landings where the tilt axis cross bar could've been damaged?

    I would try swapping the servos next, or at least just move the roll servo over to the tilt position and then we can see if its the servo or something else.
     
  9. Brandon Loeser

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    Perhaps it's an issue with the resistor? Try swapping those.
     
  10. Theo Amer

    Theo Amer New Member

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    Hi Brad,

    Looks like it's the servo. I've swapped the Tilt and Roll servos. I now have exactly the same problem on Roll axis - but the Tilt axis is fine.

    We've always flown with the camera balanced as per Tabb's video - and don't think we've had any hard landings that could have damaged the tilt axis cross bar.

    I guess I should get in touch with Quadrocopter and see if they can send me a new servo?

    Theo
     
  11. TROU BAYLISS

    TROU BAYLISS Member

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    11.1 VOLTS ????
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I presume you're referring to the very first posting in the thread, Trou?

    I'm pretty sure a BEC would be in circuit otherwise the Radians and the servos would be acting as a one time fuse! :)

    Andy.
     
  13. Jason Smoker

    Jason Smoker Active Member

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    I Had the same problem yesterday on a job the yellow flashing light I just changed the servo over and its works now!!
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks for letting us know that it was the servo, Theo.

    Andy.
     
  15. Brandon Loeser

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    Andy could the problem with it have been the resistor? Just asking...
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Brandon:
    Yes, it certainly could. The resistor is actually two 2.6K ohm resistors with a center tap -- so if something inside the assembly fails, I suspect it would cause asymmetry problems. You can verify that by swapping over the resistor assemblies and seeing the problem moves with it.

    Andy.
     
  17. Theo Amer

    Theo Amer New Member

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    Yep - I tried that too (swapping over the resistors) but the problem stayed with the servo.

    Thanks for all your help with this Andy and Brad.

    Theo
     

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