S800 EVO with A2 quick flip

[djiflyer1]

Hello Community, i just had a strange problem with my new EVO/A2 in gps mode.

First i calibrated. The start was no problem, gained hight and started forward - than very fast it flip to one side app.40 degrees and recovered fast by it self - than it hovered and rotated fine - started sideways and the same thing happen again. Than i switched to Atti mode and everything looked fine - but i have to admit after this freak behavior i was rather careful on the sticks - so before i go up again, i would like to have your opinion please.

setup:
2x6s batteries mount to the center (no gimbal yet)
IMU set outside the center on the black plate between the landing gear frame.
OSD over a tbs69 with a 25mw immersion transmitter

Gain as recommended in the A2 manual it subtracted 20 of each because the copter weight is 5kg and not 7kg -- (maybe tis is wrong) is it not better to start with everything 100% and tune later?

View attachment 14627View attachment 14628

Thank you in advance for your time and help!


oh, i see - the first picture is rather smal ... the gains where basic 120 120 110 attitude 120 120 110


::

 

[Benjamin Kenobi]

Hmmm, that is strange.

How was the wind that flight? Your gains look okay but in a gust of wind you may expect to see a bit of wobble into the wind. It might be a wiring issue. Hows does it respond in the assistant? Have a look and check all you movement bars move smoothly. Could be interference by a power wire running close to an antenna? Just thinking out loud here.

I'm sure you'll fix it. What radio gear are you using?

 

[djiflyer1]

hello - and thank you for your input!
there was no wind at all and it was a "very fast snap" about 40degrees, than also a fast recover -but only in gps mode ...in atti mode it seemed ok, i work with a futaba t14sg and all dji elements are updated - i also did calibrate the sticks. The OSD i plug into the gps port of the antenna.
maybe possible to make a calibrations mistake of the second 360 - maybe i was not exactly 90 degrees ... could this maybe make a different? ..

thank you for help!

 

[Benjamin Kenobi]

No, probably not a calibration thing. It only really needs to be 45° according to the manual but we all do it to 90° and it is pretty forgiving as long as it completes properly (correct lights etc). I noticed some of your wires are hanging loose. Should probably secure them down well to stop them rattling around. Might have caused this as the PMU connected to the GPS antenna could be banging against it? Futaba is a great radio so probably not that. Keep playing with it.

Cool?

 

[soler]

I cannot see clearly from the picture but which way is your GPS pointing? The cable exit from the GPS is towards the front of the MR

 

[djiflyer1]

hello,
the gps is facing forward - maybe it is because of the IOSD - first i try to plug it directly into the pmu - the assistant told me that there is a input issue - than a plug it into the gps "cable" and it was ok - attached the confi how i install it without the zenmuse and without the 2.4data link. i was thinking maybe the immersion was to close to the IMU ?

View attachment 14638

thank you for help ..


..

 

[ddikie]

hi your settings is very small size what are your imi & GPS mounting numbers..can you share them?

 

[djiflyer1]

hello,
yes i know - the original png is much bigger - i try as jpg.

the IMU Z pos. value i did not have at this time.

thank you.View attachment 14648

 

[ddikie]

I wonder if it was the lack of the Z value that was the problem..I have mine at -1 i.e. 1 cm above ethe centre of gravity..yours is 3 so -3 cm bellow COG ..its always hard to figure this out depending on gimbal batteries etc..but for a s800 eve thee is a lot of weight quite low


usually so you might want to look again at calculating your Z - IMU position..View attachment 14653

 

[djiflyer1]

hello,
with Z -1 do you have a gimbal/cam and 2x 6s under it ? i only have at this time 2x6s mounted directly under the center plate.

 

[ddikie]

hello,
with Z -1 do you have a gimbal/cam and 2x 6s under it ? i only have at this time 2x6s mounted directly under the center plate.

yes Zenmuse & NEX7 & heavy battery 6s 10900 mAh

 

[djiflyer1]

this is strange ... Z -1 on your heavy wight seams very little - but obviously it works - than mine with only two batteries and Z-3 seams too much - i think i try Z-1 and go out and test it.
thank you

 

[djiflyer1]

i just held the evo 90degrees to the front and grab him on his two blue balls (the anti-vibrating rubber things) ... this i the with the 2 batteries the gravity center in Z right ? this way with z= 0 the position of my IMU was correct...?
i just came back from a test flight - works fantastic at atti. super happy - very quick just nice .

but at gps mode - same thing - "maybe" a bit better -the only difference was IMU Z value from 0 to 1


i hope this videos shows the behavior a bit - but it is hard to see on this shaky video. it does it with very little stick movement by it self ...


http://youtu.be/bQ7_UzGnFcQ

 

[ddikie]

Its always difficult to tell to be honest does not seem too bad in GPS mode..could it have been a small gust of wind?..anyway take care and face flying!!

 

[Louis O'Dwyer]

Its always difficult to tell to be honest does not seem too bad in GPS mode..could it have been a small gust of wind?..anyway take care and face flying!!

Hi ddikie! sorry to hijack the thread here, I see you're using a NEX7 - tell me what settings do you use on the camera, for best video and pics? Thanks! Louis

 

[djiflyer1]

yes i know its difficult to tell - i just hate when he does something by it self ! ... and again - no wind ... i keep on trying to shift the IMU in Z - hopefully someday it works ..

 

[alpine-aerials]

Have you ever had an ESC beeping in regular intervals? I know it only happened to you in GPS mode but maybe you simply don´t fly a lot in atti...

I had this behavior with a s800 non evo in the past. It was a faulty connector on the way from the MC to the ESC. I don´t know the a2m but the wookong plug that plugs the GPS into the PMU does not have a pull safety so I glue those two things together with hot glue. (which is removable but secures the connection).

Greetings

 

[djiflyer1]

Hi - thanks for your advice - i will open it up again and recheck the connection - this is only the 3rd time that i fly this evo - an it works great on atti mode - just not gps...

thanks again ,

servus und viele grüße aus münchen .

 

[djiflyer1]

just for information: DJI exchanged the complete A2 unit with a new one - something must had been wrong with it - the evo should now "also" fly great in GPS mode -

all the best and thanks for help and advice.

 

[mikeesidney]

Hi djiflyer1. Did you solve problem with on GPS mode flight ? I'm having same problem with my EVO/A2 on GPS mode too. When i switch to GPS in 5 seconds it start wobbling like crazy and i switch back to ATT mode and it back to normal condition (stable). Please tell me what should i do to solve this problem if you already have solution to this matter. Thanks buddy.