Drifting problems / white LED

[Sebas600]

japp that is annoying especially if you want to keep the frame in balance.

Seb to your question before. You will have to give up pitch control until you found your right gains if you want to trim them with X2 and X3. In the auto pilot setting give normals gains those that you want to change X2 and attitude X3 or vice versa, and the camera gimbal if you dont want to deactivate it completely gain 0 i think its called for the manual control speed or deactivate the gimbal completly for you tests.

Thats what i meant before with strapping down you IMU. The frame and IMU are fixed to each other solidly. There is nothing the one does without the other !

I'll try of fix some of the software next week. Lots of crapy weather coming my way so no hurry.
My IMU is now fixed firmly no rips but some über sticky automotive double tape, no foam. can lift the entire MR with IMU.

Thanks again for all the support guys!

 

[Sebas600]

Oh and forgot,

- Compas was calibrated before first flight. Only remembered when saw instructions. Will do this again
- AUW was around 6700 grams with 50D with ML (yeah yeah going to buy something else for this)

 

[Sebas600]

So here to report back on the progress.

That MR holds place very good in Att. nearly no corrections needed.
BUT then when I switch it to GPS mode it starts moving forward/slightly left.

What can be wrong?

If the IMU and the GPS don't exactly match up in line, without correcting this in the assistant, can this cause the problem? (this could be couple of mm)

I've taken the very COG of the craft with the batteries on it and put that in as the point from where the IMU and GPS are.
the IMU is 9cm above COG and the GPS is 26 cm above the COG.

Haven't re-calibrated the compass yet, will do so tonight. planning on flighting tonight sins there is no wind then.

 

[Sebas600]

Today I flew again. after takeoff the MR worked perfectly! GPS held position great. had my neighbor film it to show for defective behavior. weather was perfect no wind at all.

I landed the MR and we stopped the film. As I was not in for carrying the MR further than needed I decided to fly it over the small fence and to the edge of the car park next to the field. Did not change batteries or touched anything. so i took off again and flew it over the fence in att. Then to go over the fence I put it in GPS again..... when it started to drift again!!!! white LED and all... Landed it on the parking, took out the cam and taped it again. To show the problem I lifted off put it in GPS not touching the sticks to show the drift.

What the hell can be causing this????? I am clueless sins it flew perfect and after touch and go it didn't hold position.

I'm also going to refit the GPS to one of the arms. This isn't working. it doesn't fit in the box anymore and I have to take it off every time now witch can't be good for the wire after some time.

Any ideas on this little mystery?

 

[BorisS]

Damm its a hard one to pin point ! The only two variables in the equation that changed in my eyes is the lipo has been drained which i cant link to anything and that you changed from an open field to a area with trees and other obstacles around. But this is also a week explanation. The only thing you can check now and I would do that is to do the same run again. Once in the open field take off landing take off test GPS hold see if there are no issue and than again from the same spot take off landing were you had the issues. I just know that in the garden of my neighbors in vienna that is small and has high trees around it I get very different GPS performance. On some days it holds on other days it drifts off and is not usable. All this is with no red lights blinking thus full lock down. In the open field though luckily up to now it was always performing well.

I am also i little confused lately about the LED indications that WKM if giving off. I think they changed some stuff in their firmware not announcing it. For example since switching to 5 or 5.02 I get a constant green LED for 5 seconds until it starts indication its SAT status and the flight mode it is in. Before having a bad position hold in my friends garden i didn't get any white flashed with it. Now a drift off in GPS is also accompanied with white flashes.

Boris

 

[Sebas600]

The distance between the two films is 10m in the first the trees are in my back and the next in the front. trees should not interfere with gps right...
the lipo had more than sufficient power left. and where at 19V (5S)

My test yesterday with the drift was also on a small field with trees around it, could this cause the problem? Sounds unlikely but maybe it's not.

Already took off the GPS and going to refit it monday.

Have a nice weekend guys!

 

[BorisS]

No it shouldn't be a problem ! But at the same time before you go crazy on finding an issue on your bird, give it some more tests if you find some exterior influences that might effect the bird. Full SAT lock down dosent automatically mean the its good GPS info.

http://www.kowoma.de/en/gps/errors.htm

gives some insights on this.

Boris

 

[DaveM]

@ Boris

The green LED flashing is that it has recorded the forward direction or
Home point successfully for IOC.


Dave

 

[BorisS]

Thanks Dave,

i was confused Didn't try or consider IOC yet and don't have it assigned so I didn't expect it would already be part of the LED feedback !

Boris

 

[Sebas600]

I will refit the GPS on a boom. have an extra motor mount for that. will not use a pole but will get it half way on the boom.
Could this cause a problem for the compass? sins it's very near an engine/magnet...

will then test it on various sites and see what happens. Hope the weather will permit it, it's cold down here.

 

[Sebas600]

So redone the GPS to the boom and just flew out on an open field. everything worked great, at first... after a couple of min in to flight the white led started acting up again. even in the att. mode but this probably is because it's -2c at the moment.

will do the test again when the weather is better.

 

[PapaRomeo]

I have had similar experiences and almost everytime if I roll my quad from side to side. In ex. if I slighty (1 or so metres) push it to the left then to the right and back and forth and then the white led goes on. Then in GPS mode it starts to drift and become very unstable. Flipping to attitude mode doesn't help either. On the other hand I can fly the quad fairly aggressively but simple left to right sliding is no good...

The quad I have been using is DW CX4 with 11x5 props and Robbe Roxxy 2834/10, with 30A RCTIMER escs. My roll and pitch gains are approx 150.

 

[Sebas600]

Do you have some pics of your setup? The whole thing and where avionics are placed and so?

Thanks

 

[Wavev]

Hi,

I posted similar findings on another board weeks ago. I believe the firmware needs to be updated for I have video of stable flights
In previous firmware updates but not on 5.02. Symptoms are white lights and drifting in gps mode. AT&T mode is almost perfect.

 

[iceman]

After having several problems of my own and reading this and other threads it seems obvious to me that there is an issue with the DJI WKM FC, I think someone from DJI should start reading these posts and get to work on a solution. It seems DJI started out well but now seem to have bugs in the system. Only my opinion not based on concrete proof but worth a thought.

 

[lperagallo]

After having several problems of my own and reading this and other threads it seems obvious to me that there is an issue with the DJI WKM FC, I think someone from DJI should start reading these posts and get to work on a solution. It seems DJI started out well but now seem to have bugs in the system. Only my opinion not based on concrete proof but worth a thought.

Iceman,

Exactly what issues are you having with the Wookong? Your comments about an "obvious issue" with the wookong is interesting. I am a DJI dealer and I support what I sell. I have many happy customers flying their multirotors fine. The issue with the white flashing LED is mentioned in the manual. It is a stability issue within the control system generally caused by vibration or mounting issues with the IMU. Seabas600 mentioned that he is flying in -2 temperatures. That could be part of the issue. If he did not stabilize the temperatures of the gyros before taking off there will be an issue. If you go from a warm environment, (coming from a car or house) then go out and fly it in the cold it will become stable as it cools down. That happens with most Gyros. The white led can also be caused by a weak mount. You need to firmly mount the IMU on no more than a .5MM tape. We also put a tie wrap around the unit just in case the tape comes loose. You also should balance your props and motors. The motors will be rapidly changing rpms during operation and an out of balance prop will cause unpredictable vibrations at different speeds. These motors are turning quite fast so vibrations do cause issues. You also need to make sure that your position settings are done properly and you have the proper sign in your numbers.

All of these so called issues are covered in the manual and in many posts on all different forums. If you'd like to discuss your specific issue please feel free to PM me, I'd be happy to assist you. I also can make sure that DJI is aware of your concerns.

Lou

 

[UAVproducts]

Flashing White LED the majority of times is disruption of Attitude. This is the same with all DJI autopilots since the beginning. We have been carrying and flying DJI's for over 5 years. The original XP 3.1 for helis would flash the white led if you mounted the IMU on an angle, if you had vibes etc.. The white LED is telling you something is not right.

For example, you can fly a WKM and yank it back and forth and/or fly aggressive and can get the White LED to come on. Hold hover and it goes away.

Now if the XYZ numbers are off its sensing a mounting disorder (or attitude). It is trying to make corrections (algorithm) thinking the IMU is mounted somewhere else. This is the same as if the IMU was not mounted straight or on an angle etc..

Vibrations: Its internal dampening is picking up vibrations and is being "shook". Just like on a gas or nitro heli that is not tuned the DJI Autopilots will show the white LED.

I understand it can be frustrating. But check all the little things and in the end it will be much better.

 

[GGoodrum]

I agree that it might be an issue, going from warm inside temps, to freezing cold, for the IMU. I don't even venture outside, much less fly, if the temps dip down below the mid-60s, and I've never seen this white flash issue.

-- Gary

 

[UAVproducts]

Yes, i agree temperature fluctuations will cause the White LED also.

Gary,

Mid 60's is beach weather here.

 

[lperagallo]

Yes, i agree temperature fluctuations will cause the White LED also.

Gary,

Mid 60's is beach weather here.

We were in the 30s until this week in Indianapolis when it's decided to get to 60s with high winds. I'd rather fly in wind then in the cold. I did learn the hard way about a 30 degree F swing. It isn't pretty!:dejection: Now I wait 15 minutes before taking off after I take it out the warm car.

Lou