Yaw uncontrolled clockwise turn

Discussion in 'ALTA' started by alex ryan, Nov 9, 2015.

  1. alex ryan

    alex ryan Member

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    Hi,

    So I was out flying today and the ALTA was performing well until my last flight when it started to yaw clockwise at a slow but consistent speed. I only flew in manual and height mode.

    I landed and checked that all my props were good, my motors weren't hot and the batteries and connectors were good. I double checked the trim on my radio which was centred. I took off again and the same thing was happening. So I landed and called it a day.

    I inspected the data, but couldn't really work out what was happening.

    Any ideas what could be the cause of this?

    I had already been flying for about 40 minutes before this happened. The only difference in this flight was that I was using a newish set of batteries (20 cycles), with newly soldered EC5 connectors. Also just before this flight I carried the alta and m10 to a new tack off position and in transit I bumped the gimbal. It is very unlikely, but thought it is possible that the pan arm may have slipped a little throwing it off balance (but I'm not sure this would cause a drift in the yaw)

    I have attached the data log for this final flight if anyone wants to have a look. I had to change the extension to txt so I could upload it, but you should be able to change it back to csv and it'll open in xcell.

    Cheers
     

    Attached Files:

  2. Gary Haynes

    Gary Haynes Administrator
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    Alex check the trim button on your TX. Maybe it was bumped and rather than having a zero value now has a +/- value entered.
     
  3. alex ryan

    alex ryan Member

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    the trim was definitely centred. This was the first thing I checked.
     
  4. Gary Haynes

    Gary Haynes Administrator
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    Send the question to the support email. Ask about the Yaw values and Yaw control position in the area of 1:38:24. I see a neutral Yaw Control (1500us) while you are getting rotation counter clockwise (negative) in the average of -1 d/s.
     
  5. alex ryan

    alex ryan Member

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    Thanks Gary,

    I have sent through the flight data to the support team and awaiting a response.

    I have not really delved into the data stuff beyond looking at power consumption and temperatures before, so still trying to get my head around what all the data actually represents in the real world. Thanks for the tip.
     
  6. Gary Haynes

    Gary Haynes Administrator
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    There is a list with short descriptions of all the values in the Alta manual. Lots of data. Please update this thread with the answer you get back. We are learning how to interpret the data.
     
  7. alex ryan

    alex ryan Member

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    Hi Gary,
    So the team at FF analysed the data and said it didn't look like the ALTA was doing what I described it was doing.
    They said that this could have been due to the ALTA moving while it was booting up and therefore recording data that wasn't completely accurate. I took it out for a brief fly this morning before going to a job and everything was working fine, so it looks like this is what happened. Good lesson: If in doubt reboot. You'd think I would've learnt this by now.
    They also said to turn the gimbal on after the booting process. They didn't say why, but I assume this can cause some errors too.
    I'll have to have a look at those descriptions of the values, I must have skimmed over that section in the manual. I'm really getting into this data stuff. I hope to be a data master before too long (or at least something more than a novice). I've been making a few cool looking graphs, but it would be nice to know what they are telling me. ;)
     
    Justin Marx likes this.
  8. Gary Haynes

    Gary Haynes Administrator
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    Interesting since the section I looked at was during flight. And totally agree that the MoVI should either be off or in kill mode when you put power to the Alta. You don't want the Alta spinning or moving during initiation.
     
  9. alex ryan

    alex ryan Member

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    Oh yeah, I always have it in kill mode. But now I'll just turn it on after just to be super safe. Yeah I thought I was seeing some anomalies with my cool graphs, but maybe just dont understand acceptable values for the different parameters. I wonder if freely will release an app that analyses the data in a way that can make easy sense of it?
     
  10. Fabien Deregel

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    Hi,
    turning the gimbal ON after the flight controller boots helps to prevent having EMI and magnetic gremlins disturbing the Alta's flight controller compass during it's calibration ( boot).
    Also, maybe it can help, check carefully that your props are correctly tightened ( not too loose but also not too stiff..) as if they can not align correctly, this generates a small but bad vibration and this can disturb the IMU readings and lead to uncontrolled yaw spinning.. ( valid for all kind of controllers..)
    Best regards,
    fabien
     
    Steve Maller likes this.

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