Clockwise Yaw INOP. All ideas welcome.

Discussion in 'Cinestar 8' started by MIke Magee, Sep 14, 2013.

  1. Gary Haynes

    Gary Haynes Administrator
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    It should maintain altitude.
     
  2. Sebastian Meredith

    Sebastian Meredith Active Member

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    Yes under normal operating flights ... I was wondering what Mike's was doing with the issue he is having
     
  3. Casey Van Nyhuis

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    The test Mike did where he kept the booms in the same spot but plugged the motors into brushless controllers one position over should have ruled out the BL's and distribution ring (i think). If there was an issue, then it should have swapped the symptoms and he should have had trouble yawing the other direction.

    Does this make sense or did that test only prove things in my head? o_O
     
  4. Sebastian Meredith

    Sebastian Meredith Active Member

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    Casey, would that not just eliminate the motors perhaps being faulty?
    Would you not just end up with props spinning in reverse to their intended direction?
    The BLs should they be faulty would still behave badly even with other motors on them. I would try swop out the PDB.
     
  5. Casey Van Nyhuis

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    But if plugged in correctly the hypothetical faulty BL would now be controlling a motor going the opposite direction. So it should cause the yaw issue to switch to the other direction. Right?
     
  6. Sebastian Meredith

    Sebastian Meredith Active Member

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    Theoretically yes ... But the props would have to be switched as well as they might counter the yaw effect.

    Mike? Set Casey and my minds at rest will you!? Switch em, test em and let us know mate. Thanks!
     
  7. MIke Magee

    MIke Magee Active Member

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    Well, I was traveling for a couple days, but back now.

    CASEY: Per your suggestion, I tossed it into the air.

    4 or 5 9000's - and ABSOLUTELY no problems. #*&%@*@%

    So I landed, and each time, I did a ground check and the "problem" existed. I would fly perfectly (winds 9-12 sustained, Gusts 14+) and when I landed, I would (after a recalibration and pause) spool at 1/3 -1/2 takeoff power. I have full control authority counterclockwise, and (after a 3 - 5 second pause), NO control authority clockwise.

    SO, I've been chasing a ghost because I was operating with an abundance of caution considering ground and tethered bench tests.

    I'm going to toss up a quick poll to see if SOME other folks see this behavior. IF so, I will assume it's normal behavior.

    I'm out the $$$ for a FC, but I'm OK with that because I should have a backup one anyway.

    Thanks for your help and guidance Casey. This was a tough one.

    -m




     
  8. Casey Van Nyhuis

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    FINALLY! And people always wonder why it can take a long time for us to get repairs back out to them! Well i'm sorry this wild goose chase wasn't brought to a halt before you purchased a flight control. And i really hope this doesn't deter people from doing ground checks and operating their platform safely. I promise, ground checks really are a good thing ;)
    One thing i thought of last night while i was laying awake at 2 am is a small thing i noticed with my kopter where sometimes i would yaw one direction before taking off, and for some reason couldn't get the yaw to spool the motors in the other direction until i took off. Never thought anything of it because it was a 2-axis so i couldn't really "ground test" my yaw. Just out of curiosity i wonder what happens when you try yawing the direction you were having issues with first, then try yawing the direction you weren't having trouble with. I wonder if the "issue" is dependent on which direction you try yawing first.
     
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  9. MIke Magee

    MIke Magee Active Member

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    Casey, your support (and QC's support) is awesome, and I appreciate it immensely. I'm OK wit the FC purchase because it made sense and is good to have. I WILL try the test below.

    Tomorrow we fly a 3D camera. I now feel comfortable enough to try.

    Thanks for your help and I've learned a good deal about DED Reconing diagnosis. (DRD?)

    I tossed up a poll to see if this is a common issue.

    Regards,m

    p.s. thanks for thinking about all this stuff at 2 a.m.

     
  10. John Butkus

    John Butkus Member

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    Wait, I am confused. So what was the solution? Somehow you guys lost me. It is all better now?
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If I understand it correctly, on the ground, either at low powered or tethered at higher power, Mike could not yaw the CS8 clockwise....but in the air it works fine.

    Mike: Can you confirm this, please?

    Andy.
     
  12. MIke Magee

    MIke Magee Active Member

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    John, I am confused too.
    Confirmed Andy. In the air, all is OK(based on 4 or 5 flights). On the ground the symptom appears. I can recreate it over and over.

    This only became such an issue because after what appeared to be an in-air loss of R-yaw, I limited all of my diagnosis to ground/bench tests.

    Is this normal behavior? Dunno, thus the poll. Thanks to all who opined. I hope I didn't waste your cycles.
     
  13. Casey Van Nyhuis

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    This one might have shaved off about a week of functional brain activity towards the end of my life. Curios to see if it's normal for others to see. Another thing i would be curios to see is what happens if you take off, fly around making sure you have yaw authority in both direction and then land, but before shutting your motors off try yawing both directions. Not going to prove much of anything....but knowledge is power i guess.
     
  14. MIke Magee

    MIke Magee Active Member

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    That makes two of us Casey. I'll give that a try tomorrow.

    -m
     
  15. Shaun Stanton

    Shaun Stanton Active Member

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    Mike

    I will try to analyse this using system engineering statistics analysis and get back to you. No guarantee this will show anything.
     
  16. MIke Magee

    MIke Magee Active Member

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    UPDATE: To address most suggestions
    Sticks are calibrated, trim is off and I tested this immediately before shutdown after a 7 minute uneventful flight (with a cool 3D camera ) and ...

    The problem is the same. Clockwise yaw runs for a moment, if at all, and then stops.

    Oh Well. I'm open to anything. The poll didn't attract a lot of opinions.

    Thanks to all who opined!
    -m
     
  17. Shaun Stanton

    Shaun Stanton Active Member

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    Mike I ran a couple of models

    I did some statistical techniques to clean up the data, but I wont get into all of the details. I will try to make it as brief as possible.

    First, I wanted to see if any individual motor was contributing to an overall system response.

    What I did was to clean up any errors that could influence the data such as minor tilts and rolls that the Aircraft sensed while on the table.

    I was able take that data which was each motor current adjusted for error and took two averages. I took the average of the ODD motors and the even as separate columns of data.

    I was able to take a regression of each individual motor against the odds and the evens. This will show if any motor is causing a physical response.

    I can tell you that no motor is inducing anything on the system. In fact when comparing each motor against the mean of all the ODD motors I get a perfect statistical fit, in fact its the best fit that I have seen, meaning your motors are mounted pretty damn good. I get a good fit when doing the same thing against the Even motors, but there is some unknown variation in the motor response. That's a clue.

    Its not the motors but something else going on.

    Next I compared the yaw stick commands against the motors using a similar technique and found that there is no change in direction on the response curves and there is a lot unexplained variance.

    Unfortunately this does not tell you what you all ready don't know other than you can rule out motors themselves. So there is obviously a system response internally going on. Either from your RC controller or to the commands that the flight controller is giving the motors.

    1. I would take a look at the Mixer table and see if there is anything weird going on. My inclination is that there is not.

    2. I would also take a look at the yaw channel through MK tools to see if it is doing anything weird.

    3. Look at the Channel monitor in RC controller to see that it is commanding correctly.

    4. You might try to do an EEPROM reset on your MK Boards and re-install the firmware

    5. It could be a I2C issue where erroneous data is going into the BL bus, I doubt it though.

    Thats about all I can think of.

    Shaun
     
  18. MIke Magee

    MIke Magee Active Member

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    Sean, what an outstanding analysis of my situation. I appreciate how closely you have looked at this. I like smart guys.

    Here's some comments and a final question:

    1. I would take a look at the Mixer table and see if there is anything weird going on. My inclination is that there is not.

    mm - Checked it. Looks OK

    2. I would also take a look at the yaw channel through MK tools to see if it is doing anything weird.

    mm - Checked it. Looks OK

    3. Look at the Channel monitor in RC controller to see that it is commanding correctly.

    mm - Checked it. Calibrated it, Checked Trim. Looks OK

    4. You might try to do an EEPROM reset on your MK Boards and re-install the firmware

    mm - Installed a BRAND NEW FC and reinstalled the firmware

    5. It could be a I2C issue where erroneous data is going into the BL bus, I doubt it though.

    mm - I have no I2C errors, what could I look at in there?

    Thats about all I can think of.

    mm - I'm thinking at this point it could be on the PDB. But how could it be? Do you have any thoughts about what I could test there short of replacing the entire thing?

    Thanks again Sean and others.
    -m

     
  19. Gary Haynes

    Gary Haynes Administrator
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    Mike can you shoot a short video clip. Perhaps the last 10 seconds of flight in to landing and then show what is happening?
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Mike:
    Apologies -- I've not re-read the entire thread, but I'm making some assumptions:
    1. You're using Radians on a 3-Axis gimbal.
    2. Before you land you turn the Radians to Mode OFF, right?

    If the above two assumptions are correct, can you verify that you really are getting the Radians into Mode OFF, please? (Use the Radian software just to verify it is happening when the copter's on the ground.)

    Thanks
    Andy.
     

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