My CS8 goes crazy when PH is activated

Discussion in 'Electronics' started by Lauri Hakala, Apr 11, 2013.

  1. Lauri Hakala

    Lauri Hakala Member

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    First of all I'm using Mikrokopter boards on my CS8.

    Last weekend I decided to shorten all the motor cables and run them outside the booms so the copter would be faster to assemble. Everything went well and I also moved the gps/navi boards from boom #5 to boom #1 as people have recommended. I got the Cinestar as RTF package so the builder had somehow decided to put the compass on boom #5. So prior to these modifications everything worked great.

    Today I went to local football field and did the compass calibration following the instructions from Mikrokopter.de. I heard all the right signals and I think everything went well again. So I did my first test flight and the copter was really stable and flew nice and smooth, altitude hold was solid but after that I tried position hold. Whoa! My CS just rapidly tilted towards me and started to fly with speed and I immediately turned PH off and was able to save it from crashing to the trees, it actually chopped couple of small branches off :D It was really really scary. Other than that it flew perfectly. After that I drove to another spot to do the compass calibration again and got the confirmation sound again. (front boom was facing North both times when calibrating) Tried the PH and the same effect, just tilted rapidly and started flying fast towards me. So did I do something wrong when I moved the GPS board or do you think the calibration failed both times? Also I just started to think I might have accidentally rotated the GPS board when I was moving it to boom #1 or does this even matter?

    Before these modifications PH used to work good.

    Thanks!
     
  2. Joe Azzarelli

    Joe Azzarelli Active Member

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    I have my GPS/Nav on boom 7. It does not matter what boom it is on. But you may have gotten either the nav board or gps facing the wrong way. Also make sure you have a good gps lock but that would just make PH inop, not come flying at you. Also check that the switch does not turn on CH mode.. good luck!
     
  3. Jason Smoker

    Jason Smoker Active Member

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    I think you are activating COME HOME its flying towards you! Check in mk tools what switch you are activating
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    That would be my assumption, too.
     
  5. Mark Melville

    Mark Melville Member

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    The compass has an arrow which tells you which direction it should face. What they don't tell you is that the Naviboard also has a correct orientation. If its wrong the bird will flip out and take off on you. Happened to me. The 10 pin connector on the GPS and on the navi should sit directly on top of each other.
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    And both ribbon connectors on the Navi board should be on the left hand side of Boom #1 as viewed from Boom #5.

    The "home" position is set when the GPS has a "lock" (it beeps and the blue light starts blinking) before you start the motors. If you don't allow the GPS to lock before starting the motors you might be headed to the "wrong" home position.

    If you have put a microSD card in the Navi board it will record a GPX flight log data file that you can use MK_GPXTOOL (Google for it) to analyze it and see the output from the GPS board and verify what it going on.

    You can also remove the props and "simulate" what's going on by starting the motors on the ground, which will also start the GPX log file (when the throttle exceeds 40% of maximum).

    Hope this helps.
    Andy.
     
  7. Bill Collydas

    Bill Collydas Active Member

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    Lauri, I'll throw my 2 cents in here also.
    the flashing blue light should point to the front and the 10pin cable from the Navi (when looking from the top) should be facing back and to the right (5 o'clock position)

    I hope this helps>

    Bill
     
  8. Gary Haynes

    Gary Haynes Administrator
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    Joe if you are on boom 7 do you have the Nav board correctly positioned? Reason I ask is that just like the FC board it has a 'front' while it will fly with the board at a 45 degree rotation you may experience problems.
     
  9. Lauri Hakala

    Lauri Hakala Member

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    Just woke up and immediately went to check if someone had any suggestions to my PH problem and so many great ideas - you guys are amazing!

    I'm pretty sure I just got the gps/nav mounted the wrong way, had so many things in my mind. Will check the alignment first thing at office! Accidentally switching the CH on is also a good call but I'm almost sure that's not the case because I haven't changed anything from the mx-20 or from the koptertool. The copter didn't come straight towards the take off point (like normally in CH mode), I just took off front boom facing north both times. But will double check that too just to make sure. I also had solid gps lock and the gps blue led started blinking normally. Will report back this evening.

    Thanks again guys!
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    One more thought I just had: it could be that something in the Navi system is causing the copter to go into fail safe mode when you activate PH, and as such it's trying to return to home. You really need to examine your log files from the Navi board.

    I've long since had my copter configured to require the microSD card in the Navi board, or it won't even take off. Too much at risk to miss out on the many warnings and other data that are in there.
     
  11. Lauri Hakala

    Lauri Hakala Member

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    Ok, I indeed had flipped the navi/gps when I first moved them to the boom #1. So I rotated the boards 180 degrees and recalibrated the compass and now PH worked great. Only problem was that the Yaw was now drifting quite significantly. Then again today with the compass aligned properly I got only one beeb sound in the end of the calibration process and I know I should get two beebs. Yesterday I got two beebs at the same spot. I'd love to have the copter keep it Yaw axis solid because it's really hard to film anything if the front boom heading travels all the time :/

    Two pictures: first with the gps backwards, second with proper aligment.

    [​IMG]

    [​IMG]

    Steve, I would love the record those gpx log-files. So I just place a microSD card into both Navi board and mx20 transmitter. I already assigned the flight timer to one of the switches. So I just start the timer and it records my flight log? Should I use my usb-koptertool adapter to download the gpx-file after flight. Sorry to have so many questions but I have never done this flight log thing before :)
     
  12. Steve Maller

    Steve Maller UAV Grief Counselor

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    A few things.
    1. the microSD card must be formatted as FAT, and must be 2GB or less
    2. go into KopterTool and set the Navi control so that the copter will not fly unless the SD card is in. this way you will be assured that you'll have flight data
    3. when you are done flying, power off the copter, and take the microSD card out and put it in a card reader and copy the contents of the card (there should be a folder called "Log" on it) onto your hard drive
    4. download the GPXtool from here: http://www.mikrokopter.de/ucwiki/en/MKGPXTool
    Tell us what you learn! :cool:
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Lauri:
    You may have combined two concepts: The flight timer/MX20 records a separate flight log data file to the microSD card in the MX-20.

    The one that has the GPX files is the 2GB/FAT formatted microSD card in the Navigation Control Board. That starts to record a GPX log file if the following conditions are true:

    1. The GPS unit has got enough data from the satellites to get a date (this is with the new firmware). Before it insisted that you had to have a GPS fix. Of course, it's better to actually have a GPS fix so that you can record lat/long data in the GPX file.

    2. If you have set the MKTool option not to start the motors unless you have a microSD card, then you have to have the microSD card.

    3. The motors are running and the throttle is advanced beyond 40% (the theory being that the copter is flying). Note, you can test everything and get a valid GPX file if you remove the props. There is no check that the bird's altitude is increasing -- just that you've throttled-up beyond 40%. It thinks it's "flying." :)

    You may also find this helpful: http://www.quadrocopter.com/Beginners-Guide-DVD-to-MK-TOOL_p_821.html
    The content's quite helpful but the guy who made is rather strange. :) AMHIK.

    Andy.
     
  14. Lauri Hakala

    Lauri Hakala Member

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    Thanks Steve and Andy for clearing things up - great info! Still trying to figure out where the yaw drifting comes from. And also is the transmitters log file for finding a lost ship or something like that, how does it differ from the gpx file recorded in the navi board?
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The yaw drifting might be coming from the compass calibration. Can you verify that you have correctly calibrated the compass for the location where you were flying?

    The transmitter's log file will, provided that you have the MK telemetry screen visible on the MX20, log the latitude and longitude information so if you get a fly-away, you will have the last down-linked lat/long.

    Just going from memory, the GPX file recorded on the Navi Board has many more flight characteristics than are recorded by the MX20. For example, the MK_GPXTOOL program (which you can find here) will print out a summary of the compass data -- and you can see that recorded once a second in the GPX file.

    You can find details of the GPX file's contents here.

    Gary's got more experience with the MX20/MC32's logging data so he can confirm what I'm saying is true (or close to true). ;)

    Andy.
     
  16. Joe Azzarelli

    Joe Azzarelli Active Member

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    Gary
    All pointing correctly and working fine.

    I have it on this boom because it gives me the most distance away from the FC and battery using the standard extended ribbon cables.

    Thanks for caring!

    Joe
     
  17. Lauri Hakala

    Lauri Hakala Member

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    Just did some test flights and got horrible yaw drifting and the "magnet error" so I think I should try to calibrate the compass in a different location again? I also had sd card installed on the navi board so I recorded my first ever gpx files :) To me everything seems normal other than the magnetic error. Is the navi/gps boards distance from the FC precise, I just mounted it as far away as I could? Also could the motor wires running directly underneath the navi/gps be causing problems? I also attached the gpx files from my two flights, first flight was in two parts. First flight with dual 4s 5000mah, second flight dual 4s 5800mah. CS8 was carrying GH3

    [​IMG]
    Motor wires going underneath gps/navi, before had them inside tubing.
     

    Attached Files:

  18. Bill Collydas

    Bill Collydas Active Member

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    The wires could be a problem. Running them inside the tube the CF acts as an insulator.
    Can you take off the GPS and let us see a photo of the navi?
    Thanks
    Bill
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Lauri:
    Each time you go to a different location, recalibrate the compass.

    If you want to determine whether the compass is really causing the yawing problems, use MK Tool, go to the Misc page and set the compass effect to zero. That way, you are effectively disabling the compass' effect.

    As the MK Tool documentation says, with a slightly Zen-feel caused by the translation: "Compass Effect: Is a compass connected the influence of the yaw can be set up here. In that case a small number has a small, one large number has a big influence." See http://www.mikrokopter.de/ucwiki/en/MK-Parameter/Misc

    Hope this helps.
    Andy.
     
  20. Gary Haynes

    Gary Haynes Administrator
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    Lauri you may be getting some bit of magnetic interference using the external wiring under the Navi/GPS stack. I would try raising it up using some of the 15mm or longer standoffs and see if that makes a difference. You can also check, if you are using an MX-20, the amount of Mag you are geting. While in the MK screen, press and hold the SET button until the bottom line changes and you can see MAG: xx%. You want it to be at 90% plus. If it is low, simply raising the stack may help.
    Decln 1.png
     

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