Ever seen this before? M5 freak out while flying

Discussion in 'ALTA' started by Martin Osborne, Dec 27, 2015.

  1. Martin Osborne

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    Video link:

    About 20 secs in you will see the first jolt. Batteries are fine and the Movi isn't going completely limp, it's still trying to do something and we do have some control. we usually regain control and level horizon after 30 - 120 secs (unless another spasm happens).
    This happened about 5 times yesterday and twice today, but I have no idea what would cause this kind of behaviour.

    I managed to turn on the data logging for one flight, but I don't think it is the same flight as the one posted above. https://plot.ly/~MartinOsborne/57/
    At one point, there is missing data for GPS and a few other items, even though there are always between 7 and 9 sats

    Alta and M5 Carrying GH4 with Voigtlander 10.5mm and microRemote Follow Focus.

    Any ideas?
     

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  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Not sure...it could be either battery or radio. Probably not GPS.
    I have seen this happen a few times. Mostly it's a battery issue. My MōVI batteries take a good deal of abuse, and when they start to get old, they'll do this. I'll see 3 lights when I start up the MōVI and it looks good, but a few minutes into the flight the gimbal will go limp. Are you running anything else off the MōVI battery? It clearly looks like it's gone limp. If it loses signal (which will also cause it to go wonky), it will typically not go limp unless your failsafe is set up that way.
     
  3. Rolf Ableiter

    Rolf Ableiter Active Member

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    what i see is that you have bad vibrations coming to your camera (rolling shutter).
    when the MoVI is running it has to fight against these vibrations.
    try to lower vertical stiffness of your ALTA and if you use the teal isolators, try to use the red ones. This could be one of your problems. MoVIs don't like vibrations.
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    Good point. Could also be out of balance in one or more axes, although that's a pretty light payload. Or there could be a cable that's jamming the MōVI in certain situations. That's hosed me before, too.
     
  5. Martin Osborne

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    Thanks for the replies.

    I have also seen Movis do this when using them handheld and the battery dies, but I don't think this is what was happening this time because we didn't have total loss of control. All of my batteries are very new. I've only owned the Alta about 12 weeks, and only had it out a handful of times. It arrived at the same time as the bad weather. I have been using 25c LiPos as well as the 5c ones that came with the M5. Both seem fine when operating handheld. I am running power to a Connex and Redrock follow focus, but I don't think this should be too much for the LiPo's, neither have much of a draw.

    Vibrations are definitely an issue for me. The few times I've flown to date have had terrible vibrations with teal isolators. Yesterday was the first day flying with the red isolators and things are way better, though not perfect yet. I had pretty good results with output and gyro set at 5 5 and 3 3 that day, but bad results again today with settings of 4 4 when the wind was a little stronger.
    I think that this clip in my first post is also out of focus which doesn't help.
    Looking at the charts, the pan motor was working the hardest, mostly at 4 to 15%, but peaking at 45-55% regularly. I wish these numbers were recorded in the data logging.

    GH4 with Voigtlander prime lens, follow focus, and a little bit of rigging weigh about 1.5kg. Up until now I had only been flying GH4 with lens, which is only about 1kg. I think the extra weight has helped some of our vibration and wobbling problems. Should I be adding even more weight? Eating into flight times unnecessarily. Do people flying heavy payloads find it really easy to get stable footage without to much messing around?
    I'm quite happy that the balance of the Movi is good.

    I like the suggestion of lowering vertical stiffness of the Alta, mainly because I don't know what else to do.

    I enabled data logging for my entire flight today, two sets of 10,000mah, and there is quite a few sections of missing data. I have no idea if the two problems are connected, but something doesn't seem right about so much missing data https://plot.ly/~MartinOsborne/62/movi-log-271215/
     
  6. Sam Slape

    Sam Slape Member

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    Is your follow focus and Connex connected to same battery that is powering the Movi? If so all this is too much for the little M5 battery and the voltage sag enough for the movi to cut out.
     
  7. Martin Osborne

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    I agree that it does look a bit like that, but there are a few things that suggest otherwise.

    I was using 25c LiPos when it happened. 1300mA x 25 = 32,500mA max discharge
    The Connex Air Unit draws 6.5W. At a low 4S voltage, say 14.5V, this is only 448mA
    The follow focus draws almost no power when not turning. I couldn't find out how much juice it needs.
    The Movi uses about 1A in normal operation and a max of 10A with heavier payloads/extreme movements (I think this is based on M15 and heavy camera) https://freeflysystems.zendesk.com/...45-Can-I-split-the-Power-from-a-MōVI-battery-
    Maybe if the Movi is getting too many vibrations it could shake itself into a low voltage fit? Maybe it shutdown and tried to reboot?

    I have used this setup flawlessly handheld for hours on end with no problem (Even with the 5c LiPos).

    Neither the Connex or the follow focus show any symptoms of low voltage or power.

    Neither of the logs I posted here show signs of significant voltage drops.

    We still had some control. We could slowly/glitchilty push it around. And control returned after some time had passed, which I don't think would happen when it dies of low battery.
     
  8. Rolf Ableiter

    Rolf Ableiter Active Member

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    i think you should try to lower the vibrations.
    Just look at the picture when the MoVi isn't working and when it is working.
    think about shaking a water level and how good it can measure the level when you shake it.
    the lower the vibrations the better it is working. i always had horizon issues with vibrations.
    try to lower vertical stiffness and vertical hold strength. i lowered my stiffness to 5 and still have great height hold function but with much less vibrations.
     
  9. Mathew Harwood

    Mathew Harwood New Member

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    I had a similar issue whilst handheld on the back of a motorbike once. It ended-up being a half-loose motor cable connection (in the black box that the cables run into housing the main circuitry) It was showing sensor data in-app for the tilt axis but was occasionally "skipping" power because the connector was vibrating on and off the other 2 pins. If your still having troubles try checking that the Movi motor connectors are pushed all the way in. Hope that makes sense.
     

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