M10MR + Epic + X8 - shaking

Discussion in 'MōVI MR' started by Nejc Slatner, Apr 2, 2015.

  1. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    I am new to Movi and I have Red Epic with Canon 24mm with IS lens on my X8. I have a plate with 8 rubber dampeners with 4x blue and 2x black rings in the middle on one dampener.

    There was some wind when this was shot, but in my opinion footage is rubbish. Pan and tilt look solid, but roll is shaking. What could I change and where to begin with tuning?

     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,979
    Likes Received:
    807
    Have you turned off IS in the lens? I might try repeating your experiment without the IS turned on. I've spoken to some engineering folks who have said that the IS in some lenses can be confused by the motion of a copter and cause some oscillation. I never enable IS when flying.
     
  3. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Nejic i'll ask and you may have done all of this but prop balance checked, motor bell balance (getting pretty deep into balancing), checking the compression on the O-rings (hang the copter or support the arms and see whether you have any binding or to much compression on the O-rings) which may change you up to more blacks rings. Mount a GoPro and watch the gimbal and look to see if you are getting the vibration from the frame or the gimbal.

    It can be a bit, ok a lot, of trial and error to get it dialed in. Back in the Radian days I did this for one axis at a time. Really took some testing and time to get it as best as possible.
     
  4. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    Steve, with the IS off there is not much difference, only tilt axis becomes less stable.

    Gary, will check all that again, but I had Alexmos gimbal (identical build as movi) and the same camera setup with IS on before and I had more smooth video. So I don't think there are issues on the copter above the O-rings. I have retracts, so no landing gear on the gimbal.



    I have Epic with 3800 lipo on the side and the lens is 280g. What would be some typical gains for my weight setup?
     
  5. Angus Benson-Blair

    Angus Benson-Blair Active Member

    Joined:
    Jan 23, 2013
    Messages:
    147
    Likes Received:
    25
    I have to say I have always been disappointed by the Movi's performance in the air and I have never managed much better footage. I have balanced to the nth degree and made all manner of mods. The conclusion I have come to is that the Movi is a long way from perfect but still better than most. I am also of the thought that a lot of movement you see has nothing to do with gains or balancing but all due to the buffeting it gets from being on the edge of the prop wash
     
  6. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    I've checked my multirotor again and did a test flight with my Alexmos gimbal. Results with that gimbal are perfect. Now I will start with Movi from the begining, knowing that I have no vibrations from the frame.

     
  7. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    I've added full cage to my Movi M10. Now I can get higher gains, but roll shaking is still there and it doesn't want to LOCK the possition. It says GPS GOOD and 8 satellites, but position is not locked.
     
  8. Jeff Scholl

    Jeff Scholl Distributor

    Joined:
    Jun 29, 2012
    Messages:
    240
    Likes Received:
    50
    I'm wondering if a gimbal under a Coax config might be challenged from unwanted prop wash to the gimbal/camera. Typically the booms are shorter (closer to the hub/gimbal) and you have 4 highly concentrated columns of air instead of a more diffused flat 6 or 8. Add a bit of sideways flight and that column of prop wash is going directly into your stabilized happy spot.

    Nejc,
    I see drifting on the MoVI when either the Tx trims (if using a 3rd party Tx) are not centered or the unit was not completely still on start up.

    Cheers,
    Jeff
     
  9. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    Thanks Jeff, will check TX. I am using Graupner receiver and Mx-16.
    Prop wash could be a reason, but I have quite long booms and there is no problem with it on the Alexmos gimbal.

    Here a have two more tests under the same X8 copter. With IS ON I am getting quite close on both gimbals, but Alexmos is still more stable in roll axis. With IS off, Movi performs better. This is due to more solid frame without any movements at the motor bearings, which my Alexmos gimbal have.

    Alexmos:

    Movi:
     
  10. Jeff Scholl

    Jeff Scholl Distributor

    Joined:
    Jun 29, 2012
    Messages:
    240
    Likes Received:
    50
    Also double check all of your fasteners on the MoVI. Our gear gets daily use and I found out last week that a few bolts on the gimbal needed to be snugged up a half turn or so.

    Jeff
     
  11. Dave King

    Dave King Well-Known Member

    Joined:
    Dec 24, 2012
    Messages:
    2,711
    Likes Received:
    311
    NEJC

    I feel your pain. I have spent countless hours trying to cure gimbal issues.

    Have you tuned the MOVI on the ground with the copter suspended and the gimbal hanging on the isolators? You can do this with a couple chairs if you don't have anything rigged up to hang from your ceiling. I believe this is very important and has always been a very good way for me to dial in any small tuning problems. I always do this and then scope my axis's to see how sensitive they are to vibrations to various movements. I also would not rely exclusively on auto tune. If you are running a setup from autotune I would make some tweaks to it. I would auto tune as a starting point but then I would do some tweaking from those numbers. I increase the roll stiffness number until I start to get oscillations and then back it off about 8 from there as a starting point to fly.

    BTW: I have tested a lot with IS on and off using prime lenses and I have always seen better results with IS on.

    I use both the Alexmos gimbal and the MOVI gimbal and I have to admit that the MOVI gimbal is better. Both are very good but the MOVI is better. I can definitely get good results with the Alexmos but it has limits as far as how much movement it can take. The MOVI can take unlimited movements and I think its better in higher winds and much easier to tune in than Alexmos.

    I have also found that the tilt vertical CG can affect how fast the roll wants to move around. If the vertical CG on the tilt axis is off, the roll motor will have to fight the gimbal wanting to do a lot of small roll movements. So I not only make sure the roll stays in place but I see how it reacts when I move it off center. A good way to see how well the tilt and roll axis's are balanced is to use the GUI and monitor motor power. I see no more than 2-3% roll and tilt power.

    Hope these tips can help.
     
  12. Nejc Slatner

    Nejc Slatner New Member

    Joined:
    Jan 22, 2014
    Messages:
    26
    Likes Received:
    2
    Dave, thanks for your time. I have retracts, so I am tuning gimbal hanging as in the air. First I did auto tune, but later went so much higher with all the gains. I have to try the effect of the tilt vertical CG as you mentioned, since Movi doesn't have an option to balance roll vertical.

    I am strugling to find out if it is better to have higher gyro and output gain and lower stiffness, or the oposite. What are your thoughts on this?

    Cheers
     
  13. Dave King

    Dave King Well-Known Member

    Joined:
    Dec 24, 2012
    Messages:
    2,711
    Likes Received:
    311
    I think there is a good chance your roll stiffness settings are too high. I would keep all other settings (especially gyro and output settings) bone stock. I would reduce your current roll stiffness number by at least 8 and fly it to see if it has an effect. What are you motor power numbers for roll when its running and working?

    If you double checked all other settings are bone stock and get the same results with lower stiffness settings I would recommend trying this combination as a hand held and see if you get any issues. It's another great way to troubleshoot for things that are hard to find while flying.
     
  14. Marco Salazar

    Marco Salazar New Member

    Joined:
    Apr 19, 2013
    Messages:
    4
    Likes Received:
    0
    Hi Guys I'm struggling with something similar. We have a X8 with Movi M10 and today we had shaking issues with our MOVI M10. We are running a RED Dragon with Cooke 18mm S4 lens. Our gimbal has the full cage upgrade and we use retracts. When we fly with Blackmagic 4K and Canon L series it doesnt shake at all. If you guys have experience on this setup we'll really appreciate any advice. We have to fly tomorrow with an L Series lens. (hope this solves the issue).

    Marco
     
  15. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Marco have you weighed the the Dragon/Lens to see if you are approaching any weight limits on the M10? What type of vibration dampers does your copter have? Are they maxed out and basically bottoming out while in flight at any time?
     
  16. Marco Salazar

    Marco Salazar New Member

    Joined:
    Apr 19, 2013
    Messages:
    4
    Likes Received:
    0
    Hi Gary thanks for your support. The gimbal with camera & accessories is 5.8kg. The x8 flyes perfect but the gimbal stared to shake. After reading some posts today we tried playing with the gains and the roll got better. At the end we decited to move to a Canon "l" series and in case a client wants to use a heavy prime we will use a m15.
    About the dampers we are using a syndrone frame that has a star very similar to the cinestar plate. We also have a cinestar frame but we believe this one's better for heavy payloads.

    We'll be flying tomorrow... I'll share some posts.

    Pura vida

    Marco

    www.cinemacopter.com
     

Share This Page