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How to get AlexMos to stop Vibrating? Hit it with a Hammer?

Discussion in 'AP/AV Mounts, Stabilization, etc. Discussion' started by R_Lefebvre, Mar 4, 2016.

  1. R_Lefebvre

    R_Lefebvre Arducopter Developer

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    Posted by R_Lefebvre, Mar 4, 2016 #1
    I'm just about to the point of attempting percussive maintenance on my AlexMos 32 bit controller and gimbal. I have been trying to get this thing working on and off for 2 years. It's always the same thing. Accel calibration is done, multi temp, etc. It's balanced as well as I can given the friction/stiffness of the wires.

    I tune the PIDs, have used the notch filters, etc. Everything is good, then I take it outside to use it, it vibrates. If I turn down the gains so it doesn't vibrate, it's not stable. So I retune the gain on one axis, and another starts vibrating. Retune that one, another starts vibrating. Get it all good, change the battery, it starts vibrating. Reduce the gains, it stops vibrating, then starts shaking on another axis. Retune that, another axis starts vibrating.

    I'm just going around and around in circles.

    I've had this nice Octo for 2 years now waiting to take some video, and I just CANNOT get this POS working. I've tried 3 different gimbals. 2 different controllers, several vibration damping systems, it's just always this circular pattern of tune axis to stop vibration, another starts vibrating, fix that, another vibrates. The only thing I can do is detune it to the point where it doesn't work anymore.

    At this point I'm ready to sell the Octocopter because it's useless to me if I can't get a decent gimbal on it. I'm extremely hesitant to buy another system, because I have no guarantees it's going to work, and I'm sick of buying gimbals and controllers.

    Is it just me? Does anybody have AlexMos working right, reliably?
     
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  2. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 4, 2016 #2
    The best fix for a flaky AM is a Phobotic Centerpiece.. Sorry,.. I went there...
     
    Last edited by a moderator: Mar 4, 2016
  3. R_Lefebvre

    R_Lefebvre Arducopter Developer

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    Posted by R_Lefebvre, Mar 4, 2016 #3
    Yeah, I've heard that. But I'm not buying any more gimbals unless there's a guarantee it will work.

    I was really only interested in aerial video for personal use. I'd just as soon go buy a Solo, and if it doesn't work, just return it. I wanted the higher quality from a Nex vs. GoPro, but at this point, I got nothing, can't do worse than that.
     
  4. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 4, 2016 #4
    Ya, the Phobotic works good on high quality super well balanced gimbals. But as we cannot control the gimbal quality on the DIY front it's really up to the builder to get it right.

    I know your pain Robert. I threw a ton of cash out on cheap gimbals and controllers.

    Famous Hobby and Phobotic play nice together but it's a few bucks more for sure.. Still WAY cheaper than the Movi etc. though.
     
  5. R_Lefebvre

    R_Lefebvre Arducopter Developer

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    Posted by R_Lefebvre, Mar 4, 2016 #5
    Well, I'm not using cheap DIY gimbal, they are nice CNC aluminum gimbals. Actually, the best one I've had is a 2-axis (no yaw) home-built I made.
     
  6. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 4, 2016 #6
    Hmmm, we have seen issues with aluminum as it has a tendency to ring. The motors put out a high frequency vibration that causes ringing that transfers to the IMU. This may be an area to look at with your current issue. Jakub and Phobotic gave up on aluminum as a material for this reason. Although if you can find a way to damp it..
     
  7. jfro

    jfro Aerial Fun

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    Posted by jfro, Mar 4, 2016 #7
    How far are you from buffalo N.Y.? Maybe we can swap some gimbal help for Pixhawk help.
    I am about 1 he 2o minutes from Buffalo.
     
  8. Carapau

    Carapau Tek care, lambs ont road, MRF Moderator

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    Posted by Carapau, Mar 5, 2016 #8
    If you want a gimbal guaranteed to work, it's simple. Movi M5. Its not the cheapest but is not a bank breaker either. The time you will save by not messing around with it the whole time makes it much more economically viable than the headline ticket price would suggest.
     
    3 people like this.
  9. SleepyC

    SleepyC www.AirHeadMedia.com

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    Posted by SleepyC, Mar 5, 2016 #9
    This is not 100% true. I know one HIGH end manufacturer that made a very solid frame, and used probably 10 different sets of gimbal motors, worked hand in hand with the Phobotic developers and still could not get a gimbal that worked on a regular basis.

    The amount of set up required to get a decent tune was staggering and in no way acceptable to a professional who may have a DP change a lens on him and create an insane amount of tuning.

    Glad it works for you, but it was a time suck for me.

    Move M5 all day ESPECIALLY after the release of the new Firmware. Nothing touching it!
    But even the Gremsy H series is WAY better than the Phobotic.
     
    2 people like this.
  10. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 6, 2016 #10
    Well ANY gimbal will need to be rebalanced when changing a lens!

    We have changed CAMERAS from 5D to Sony A7s on set with no need for retuning... A simple balance and good to go. Balancing whether fast or tedious is a matter of which FRAME you have and is nothing to do with the controller.

    Average tuning time on a Phobotic (using Auto Tune) is ten minutes.

    The high end fellow you speak of could not get his gimbals going due to the fact he was building in ALUMINUM. Once the ringing issues with aluminum was pointed out to them (by me) he they switched to CF ... The reason for dropping Phobotic was due to a personal falling out... Phobotic co-designed the gimbal he is currently selling.. without compensation, or acknowledgement I might add..

    I just wanted to set the record straight here I will not respond further
     
    Last edited by a moderator: Mar 6, 2016
  11. Cameraj

    Cameraj Member

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    Posted by Cameraj, Mar 7, 2016 #11
    Nope, I have both. Movi m5
     
  12. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 7, 2016 #12
    I didn't know the M5 uses AlexMos controllers. ;) (That was the comparison that was made Phobotic/AlexMos)

    But seriously you can't compare the Phobotic, or any other DIY controller for that matter, to something like a Movi without installing the controller ON the same frame. In this case an m5 frame. When I build "Movi Clones" with Famous Hobby frames and Phobotic Controllers, editors on high profile TV shows tell me they can't tell the difference in the footage.

    NOT arguing that the Movi is not an excellent piece of gear. It is. But a prosumer alternative aimed at avid hobbyists / semi-pros exists and saves you $1500 USD.
     
    Last edited by a moderator: Mar 7, 2016
  13. Posted by John Doecliff, Mar 7, 2016 #13
    I'm in the same boat. Just bought my first non go pro gimbal with Alexmos. I have got it semi good on the stand but know its going to need more work. I just mounted it on my MR today and will continue with the tuning. The more I look into it the more I just want to get a movi. I am also looking for an alternative that's better than an alexmos but cheaper than a movi.
     
  14. Lanzar

    Lanzar Member

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    Posted by Lanzar, Mar 8, 2016 #14
    You should throw it away 2 years ago and buy a movi m5 and you would be working and not trying to figure out what the hell is wrong with gimbal, tuning pid and so on. But the bright side is we learn from our mistakes. Some even cost a sh.t load of time or money.
     
  15. Posted by John Doecliff, Mar 8, 2016 #15
    I think we all agree that the movi is the best but are there others worth mentioning? is Align any good?
     
  16. jakuban

    jakuban Member

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    Posted by jakuban, Mar 12, 2016 #16
    AlexMos always needed lots of patience and knowledge from the user to make it working very good. But that's just one side of the issue. Second one is gimbal mechanics. When DIY brushless gimbals entered the market no one realised how important it is rigidity and precision of gimbal mechanics. Obviously it has changed during last years but I would say that for someone who is about to start to build gimbal with AlexMos it is even harder now than 3years ago. AM has changed a lot, it is much more advanced and requires knowledge and quite big experience.
    At this moment I am really satisfied with AM. It works really amazing in InfinityMR. Of course there are some minor issues to address, but overall it performs great. Few days ago Kopterworks team wrote on their FB that InfinityMR can compete with Movi ;) for me that says a lot:)
    If anyone is interested about InfinityMR or MR-S here is a thread:
    http://multirotorforums.com/threads...rmance-gimbal-for-gh4-a7s-size-cameras.24789/
     
    2 people like this.
  17. Posted by John Doecliff, Mar 12, 2016 #17
    I would agree that there might be some frustrating times as your learning but overall it's affordable and works very well once you get it figured out. I just bought my first real (non go pro) gimbal with alexmos and over the course of 2 or 3 weeks in my spare time I was able to get it going fairly well. I read a ton of postings on several forums, watched a ton of you tube videos and slowly read and re-read the manual and got it going.
     
  18. violetwolf

    violetwolf Member

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    Posted by violetwolf, Mar 12, 2016 #18
    Another line of super solid frames that I found are the Famous Hobby Movi knockoffs at a seriously attractive price point. They're extremely well built as is all the FH stuff. Virtually identical to the Movi's http://www.uavmediapros.com/product-category

    Yes I'm their North American rep, but only because I truly love (and use) their products, including the gimbals. Best bang for buck out there IMO.

    Kuba (jakuban) makes great stuff too and I don't hesitate endorsing him and his products.
     
  19. Mediakopter.no

    Mediakopter.no Member

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    Posted by Mediakopter.no, Mar 16, 2016 #19
    I know your frustations a bit to well. After three gimbals and trying 8 bit alexmos, and Phobotic, I have now settled with the Hd Air Studio InfinityMR encoder gimbal, with 32bit alexmos. I bought the first versjon of it, and got it working real good in a few days. Back then I had to do programming and a bit of assembly myself. Jakobsen hjelped me out with a few kinks, and to day, all produsers I have worked with are really satisfied with the results. From what I understand, the gimbals are pre assembled and programmed when you get it now. You will probably have to do some adjustments in the GUI still, but it should be fairly easy to get it working,

    After over a year with perfect footage, also in really demanding conditions, I highly reformmend the InfinityMR.
     
    2 people like this.
  20. jakuban

    jakuban Member

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    Posted by jakuban, Mar 16, 2016 #20
    Yes, right now all gimbals are delivered ready to use out of the box. And I know that most users don't even open GUI to change settings, even if the use different cameras!:) I spent lots of time on finding universal settings that just work with different camera configurations and from users reports it seems that they work great.

    Thanks Knut @Mediakopter.no@Mediakopter.no for your feedback. Much appreciated!:)
     
    2 people like this.
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