Wookong M 4 minute crash

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Oscar754

Member
Hi
So first I would just like to start of saying that I believe I have done my research (of course there is always more to learn) and my fair share of crashes over the last year while I have been learning. I learnt to fly on a HBFP v2 and rebuilt the thing at least 3 times over. Recently got into the multirotor flying after some basic fix wing foams that I built. In the summer I built a tricopter from flitestest's bat bones kit using a KK board.

Anyway getting to the point I have now got a second hand Cx4 quad which I got second hand however never flown. I took it apart and rebuilt it so i knew everything was how it should be, programmed the wookong m flight control and have had probably maybe 10 hours flights on it over the last couple of months. However about 2 weeks ago the back left motor randomly dropped as I was hovering it and it went strait into a tree. I usually fly and land in normal mode so I have full control however it was windy and as when I get it fully ready to film I'm going to be filming in high wind because I'm filming sailing I wanted to test out the GPS hold in strong wind, now GPS hold had worked perfectly before this (to my limited knowledge)but here it failed and as I wasn't in full control I couldn't correct the dropped motor so it crashed. I have now fully rebuilt it and have flown up until the past week.

After about a week maybe 2 I noticed that on start up there is quick green yellow flashing from the LED , this means abnormal compass data so I have resetup the compass yet this still happens, now this maybe wrong but I have continued to fly and everything has gone smoothly up until this week where the quad now crashes at exactly (give or take 10 seconds) 4 minutes after take off if in GPS hold mode. It has now crashed 3 times at 4 minutes in GPS hold, on the last flight tonight i flicked it too normal at 10 seconds before and flew around perfectly happy until 4 minutes 30 when I got curious and flicked back too GPS hold to see what would happen. it immediately pulled back and went strait into the ground. Oh and there were no yellow or red flashes to indicate low voltage and when charging only 1800 Mah was put back into a 5000 Mah pack.

Troubleshooting : I checked all motors for temperature after the flights so I knew it wasn't them failing, this goes for esc's too.

Re done compass calibration

checked assistant software to see if anything could be found: nothing seemed to be wrong.

I'm going to try and reinstall software to the wookong m if this can be done.

Any more ideas would be very welcome.

Thanks for your time and help in advance !!
 

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222GR

Member
out of curiosity do you have a flight radius limitation set in the wookong software?
i learned an interesting lesson the other day about GPS mode, home points, and walking a powered aircraft to another takeoff point other than its recorded home point.
 

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Oscar754

Member
No flight radius limitation setup and have currently only flown out the front of my house so only one flight and takeoff area so far. I wait for the quick flashing of the purple light before takeoff to show the homepoint has been set.
 

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222GR

Member
gotcha. just something to rule out. I discovered it's an easy thing to not think about and just "relocate" without pulling the battery. You can safely fly around for a flight duration past 4 minutes in other modes like manual and atti?
 

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Oscar754

Member
I have yet too try attitude mode as it took me the last two flights too rule all the other components out (still haven't completely but almost certain it is the FC atm) and only tried flying in manual past the 4 minute mark today and it flew very smoothly with no indication of any problems until flipping the switch back too GPS hold. GPS hold worked well up until about 3:50 when i put the quad into manual mode. I have had flight times of about 8 minutes before when flying gently like i was today. Thanks for the help though!
 

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Oscar754

Member
The only thing i have come up with so far that it is a flyaway trigged by something at 4 minutes but I still have full control over the quad just not enough to stop it from crashing, its just like something is fighting me for control
 

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222GR

Member
sure thing, i'd definitely try to fly your batteries off in diff modes to rule out other things and solidify gps errors.
I would agree that it seems FC related but it could be lots of things.
Do you have flight data recording like iOSD?

I've had 2 dji FC's that the compass canbus connection seems loose and scary.
Could be faulty compass or magnetized compass, maybe try degaussing it and recalibrating with software (can't remember if wkm does this like Naza)
Could be IMU vibrations, older version, position, etc...

Sorry I'm not more help but you'll get more input and test your other flight modes too.

I hate gps mode, I don't trust it yet its almost a necessary evil.
 

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222GR

Member
Oscar754 said:
The only thing i have come up with so far that it is a flyaway trigged by something at 4 minutes but I still have full control over the quad just not enough to stop it from crashing, its just like something is fighting me for control
Click to expand...

Maybe you have a neighbor who's messing with you? haha
 


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222GR

Member
I'd be tempted to tether it above the ground with some range of movement and test gps mode in a hover and see if it's repeatable without risk of damage
 

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Oscar754

Member
Yes I updated the firmware earlier to the latest one 2.16 (i think) put there still is the flashing green and orange light on startup saying that there is a compass error. I will have a look at recalibrating now and will see if it makes a difference tomorrow
 


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Oscar754

Member
yeah having some thoughts now about how I can definitely narrow it down to begin the compass, definitely seems to make sense however doesn't explain why these last 3 times it has happened at 4 minutes in, maybe its just a coincidence. Next flight i will be landing at 3 minutes, letting props stop then taking off again and seeing if it then takes another 4 minutes for it to "flyaway"
 


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222GR

Member
this is from the 5.24 update notes.

'
  • Add alternative Yellow and Green LED to indicate Abnormal Compass Data. The autopilot system will enter into ATTI Mode automatically (ATTI and Manual Mode is free form influence.), and regain the original control mode once data is back to normal.
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Maybe I missed it, but you rushed past the obvious ESC failure saying the temperature was fine. A failing ESC doesn't get hot. Usually one of the components like a capacitor no longer holds it's charge which doesn't show up immediately, hence the four minute failure you're seeing.

Does the aircraft move the same way each time it fails? Have you replaced the ESC on the affected side?
 

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Oscar754

Member
Okay so I have just checked the WKM software and it is up to date just me getting mixed up with the OS X assistant from DJI.
Regarding the flashing yellow and green light: It only comes on before flight for about 5 seconds after power up. There is rarely a signal drop once I have no red lights .
Okay regarding the esc's I'm currently in the process of ordering some more to replace the ones on at the moment so I can eliminate that failure point completely
 

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Oscar754

Member
UPDATE: redid all the WKM software and have double and triple checked my settings and software versions.
first thing i did was once again recalibrate the compass, and joy of joys no more green and yellow flashing on reboot however won't get my hopes up until battery is charged and checked a second time
Took off and was very nervous and didn't go much more than a meter of the ground, flew all the way up until the 4 minute mark on attitude hold and no problems, then switched to GPS hold and... no problem rock steady, stayed in GPS hold too the 6 minute mark when I then switched to normal mode as i didn't want to push my luck. However at about 7 minutes in it started again, in normal mode, I was able to control it as it wasn't trying to self right itself in normal mode. One thing I have noted is that it does pull backwards first then the front motors go and it sort of just wobbles in the air each motor dropping intermittently. Anyhow i landed after about 5 seconds of this fairly gently- however mostly down to luck i expect!!! I then went and held the motors and they were very warm too touch however I could still hold them if not comfortably. I then took off again after about 30 seconds and spent the rest of the time simply hovering about 30 cm of the ground for the next minute until my first low voltage warning came on and I landed.

So seems to me as though I could maybe eliminate the Flight controller which is a huge relief considering the cost compared to the other components.
Have no spare esc's to hand however will order some immediately and replace and will repost when I have done this.
 

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Oscar754

Member
Right esc's ordered and coming with courier delivery so hope they arrive within the next two weeks. Living in Abu Dhabi has its disadvantages
 

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