Mk motor shut down

Discussion in 'Electronics' started by Michael comissiong, Sep 19, 2013.

  1. Michael comissiong

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    Hi,
    I am having a strange issue I have a MK OCTO 2 with the new acc upgrade , but I have noticed that when i shut off the Radio that the engines all shut down , as far as i am aware this should not be , as this is the same as lost radio signal, so at the moment I cannot test the failsafe on the system ,any thoughts.

    Michael
     
  2. Gary Haynes

    Gary Haynes Administrator
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    Are you turning the radio off in flight or on the ground? ANdy can probably give us the logic but there was a change with the latest software on how failsafe operates. Triggered by an incident a few months ago.
     
  3. Michael comissiong

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    Hi,
    On the ground and while holding it about 6 ft in the air at about 50 ft distance.
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    A better test would be to throttle up to hover power and have somebody hold the copter. If the motors are idling, the copter may "know" it's not in the air.

    I have to admit that (like most folks), I've never tested the emergency "come home on RX signal loss" feature. I've used "come home" a few times, but always by deliberately triggering it from a switch on the Graupner.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Michael: Can you post some MK Tool screen images of how you have your MK boards set up -- or save the current settings to a .mkp file and post that.

    Strange to say, I've never tried turning off the transmitter with the motors idling and the copter on the ground.

    The safety feature that was added relatively recently was designed to prevent this sequence:
    1. Copter lands.
    2. Pilot fails to shut off motors (or thinks he/she has done so, but has not held the stick(s) for long enough).
    3. Pilot switches off transmitter.
    4. Copter then leaps up into the air after five seconds and goes into Emergency Come Home only to discover (in this particular incident that provoked all this), that the flight battery is exhausted, and the copter descends out of control -- and the transmitter is still off...)

    This actually happened and the pilot received a significant injury (laceration from a prop). To their credit, when I reported this to Holger and Ingo of MK they were very responsive and issued an update to inhibit emergency come home once the copter had been deemed to have landed. As I recall, the test was below something like one meter in altitude and with the throttle below a certain setting for a specific time period. The details are out on the web somewhere. I can search for them if they prove relevant here.

    As Steve says, it's entirely feasible that you're also seeing another variation on the safety mechanism if the firmware determines that you never took off and have been flying. Certainly, the behavior you describe is a good, safe, one.

    Andy.
     
  6. Sebastian Meredith

    Sebastian Meredith Active Member

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    Oh no ..... Flash backs!!!!
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sorry about that Sebastian, but your candor in coming forward with this incident has made the world safer for MK copter pilots and so we actually owe you a debt of gratitude. You have my respect.

    Andy.
     
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  8. Michael comissiong

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    Hi
    Here are some screen shots
     

    Attached Files:

  9. Michael comissiong

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    Hi,
    I have not fully tuned the octo as it is a rebuild after it lost 2 props and went swimming in a pool.
    I have replaced the fc, pdb, board only the navi and compas was saved from the original along with motors and cameras.
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Michael:
    Sorry to hear about the rebuild!

    Channels:
    Looks good.

    Easy Setup:
    Stick Neutral Point: If your throttle stick is spring loaded, 127 is the correct setting. If no spring, change to 0.
    Coming home altitude is set: Good.
    Carefree: Be careful if you do plan to use Carefree. It can bite you when you're not expecting it.

    Misc:
    If you're using firmware 0.9xx or 2.xxx, you might want to change Compass Effect from 64 to 0. Several folks, including me have noticed uncommanded yaw twitches with it set to 64.
    Undervoltage: If you are using 4s, enter the value 144 (14.4 volts). 13.2 is dangerously low. Give yourself a safety margin.
    SD card missing: If you have a Navi-Ctrl board with a microSD card, check this box.
    GPX fix missing: If you plan to use the GPS board and get GPX log files, check this box.

    Don't see anything that would specific cause motor shutdown as you described, though.

    Andy.
     
  11. Michael comissiong

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    Hi Andy,
    Could the fail safe in the MX 20 radio have anything to do with my problem , I have never set this I don't know if any thing has changed , what I might do is get a net and suspend it up about 15 ft and cut the receiver over it at least it will fall into it .
    Thanks for the assistance.
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Michael:
    I'm pretty sure that the MX-20 doesn't have the "knowledge" to transmit a motor off signal to the MK Flight Control board.

    I'm worrying that any test you do might result in more damage than you want -- like if it drops into a net will it break several props even if they are just slowing down and not being driven.

    Andy.
     
  13. Sebastian Meredith

    Sebastian Meredith Active Member

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    One small cut on hand ... one giant crash for MK kind ... :cool:
     
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  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I remember seeing the image. "Small" wasn't the word that came to mind."

    Andy.
     
  15. Gustavo Rios

    Gustavo Rios Member

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    Hi, I just realised that I have the same problem, it was resolved ??

    Gustavo.

    FC 2.1 - firm 0.90 - Dx8
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Gustavo: Could you clarify what you mean by "same problem?" When you power of the transmitter, all the motors shut down? (Which was the situation described at the top of the thread.)

    Andy.
     
  17. Gustavo Rios

    Gustavo Rios Member

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    Yes Andy, when I power off transmitter, all the motors shut down.

    Gustavo
     
  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hmmm. That really sounds like the MK "Failsafe" feature is not set up correctly, doesn't it?
    The (somewhat hard to comprehend) instructions for setting that up are here: http://wiki.mikrokopter.de/en/FailSafe

    It's a bit of a pain, but I'd start there and make sure you've got the Failsafe feature set up correctly.

    Andy.
     
  19. Dave King

    Dave King Well-Known Member

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    HI Gustavo

    I didn't read anywhere where you describe what radio you are using. I assume you are using Graupner with MK? and possibly an MX20? Regardless of the radio, you can test this function on the ground with no props. What I would do is hook up the copter with no props on up to MK tools. Open up the channels tab, start the copter up, leave all sticks to the center neutral position and then turn the radio off and see what happens. All channels should stay at 50% or value of 127. If you notice the throttle channel going down your radio has some how been programmed with the fail safe settings. It's important to double check that the Graupners fail safe settings are not programmed or set for when the radio is shut off as MK takes care of everything. If you find the fail safe functions on the graupner some how have been programmed you can simply just move to a clear program, bind your radio, setup your PH and AH and you will be all set. Just double check with a quick test afterwards to verify that its all good.
     
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  20. Michael comissiong

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    Hi Gustavo
    I have not resolved the issue as yet as I had been busy with my other systems while waiting on some new lipos for the octo ( they take a while to get to us in the Caribbean) I will have another go at it next week and post results.

    I will also try what dave has suggested.
     

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