Drone flies backwards when stick pushed forwards
4821 24 2021-1-21
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GavinM
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Hi,

First time post from a newbie owner/flyer.

I have been practicing basic manoeuvres with my brand new Mavic Air 2 for the last couple of weeks.

In just the last couple of days I’ve had a disconcerting (downright scary to me!) intermittent issue arise.

When I have pushed the right stick UP to fly the drone forwards it has started to move backwards!

I then pulled DOWN on the stick to see if somehow the command had been reversed but that also (correctly) flew the drone backwards.

This has only occurred a couple of times after which I quickly landed and switched everything off.  Next flight it flew normally.  Go figure?

Is there a trap for beginners?    Something of which I’m not aware?

Hopefully there’s a simple explanation.

Gavin
2021-1-21
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DowntownRDB
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You may have to refresh the remote controller firmware using DJI Assistant 2.  You might also try calibrating remote controller.
2021-1-21
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JJB*
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not to be rude.....but was the drone facing away from you both times?
Would love to see the flightrecord in wich this forward / aft error occurs.
Use this link > https://www.phantomhelp.com/LogViewer/Upload/

or put a cloud-link to the flightrecord.txt on here

cheers
JJB
2021-1-21
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frankymusik
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JJB* Posted at 1-21 07:31
not to be rude.....but was the drone facing away from you both times?
Would love to see the flightrecord in wich this forward / aft error occurs.
Use this link > https://www.phantomhelp.com/LogViewer/Upload/

.   
2021-1-21
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VanzPix
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JJB* Posted at 1-21 07:31
not to be rude.....but was the drone facing away from you both times?
Would love to see the flightrecord in wich this forward / aft error occurs.
Use this link > https://www.phantomhelp.com/LogViewer/Upload/

I was thinking the same way, well seen
2021-1-21
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WebParrot
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not to be rude (here, either)... Were you out-of-doors both times?  Secondarily, doing a reset (calibrating the remote as in #2) is a consideration, then check the controller settings to assure you're in Mode 2.  Thirdly, calibrate the sticks (oops... not sure if that's an option in Fly App-but if it is, make sure the aircraft is OFF)
2021-1-21
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JohnLietzke
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I also had the same thought that the orientation of the drone was not consistent with the direction the operator was facing.  

But it could also be that the stick setting have been changed from the default.
2021-1-21
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GavinM
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Thanks for the replies guys.

No offence taken to asking me which way drone was facing - an obvious mistake a beginner may make!  

On both occasions it was hovering right above its home point, not far above my head, so I could see clearly that it was facing AWAY from me.

Please note it flew “backwards” regardless of which way I pushed the right stick - UP or DOWN - so the drone/operator orientation question becomes mute I guess.

I was on my front lawn nearby my house and, as the drone started moving backwards, it unnerved me as it was starting to fly back towards the house.  When I pushed the stick in the opposite direction (DOWN) and it still moved backwards it was getting too damn close for an uninitiated beginner like me so I just took both hands off to give myself time to think clearly.  I then figured out the best way to manoeuvre it away from the house was to rotate 180 degrees and back away  - which worked a treat - and land immediately (heart still pounding, haha, you can tell I’m a “learner”).

I will take it out and have another go now and see if the problem persists ...

Gavin
2021-1-21
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Tentoes
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Well, since it USUALLY responds properly, the sticks clearly aren't configured wrong.

This is very strange behavior. I think the flight log will help answer some questions.
2021-1-21
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GavinM
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Tentoes Posted at 1-21 18:05
Well, since it USUALLY responds properly, the sticks clearly aren't configured wrong.

This is very strange behavior. I think the flight log will help answer some questions.

Yes, it USUALLY flies fine.  Just took it out again just now and flew it forward/aft, up/down, sideways left/right and rotate left/right - all worked perfectly!   

I did an IMU calibration last night just in case.  Don’t know whether that helped (?)

I will do some learning on how to find and view flight logs so I can provide feedback ...

2021-1-21
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Labroides
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GavinM Posted at 1-21 19:04
Yes, it USUALLY flies fine.  Just took it out again just now and flew it forward/aft, up/down, sideways left/right and rotate left/right - all worked perfectly!   

I did an IMU calibration last night just in case.  Don’t know whether that helped (?)

I did an IMU calibration last night just in case.  Don’t know whether that helped (?)

Probably not, the IMU doesn't affect joustick inputs.
There's nothing that can make the drone fly the same way when you push and pull the right stick.
Pushing and pulling the stick will always cause flight in opposite directions.

The situation you described can't have had anything to do with any of what's been suggested so far.
That leaves a genuinely uncommon issue that's not been encountered so far (but I can't imagine what it might be).
Or disorientation making you think the drone was doing something that it wasn't.

Flight data would be the place to look for answers but if you've updated the app to 1.2.2 or later, we can't read it.
2021-1-22
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JJB*
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GavinM Posted at 1-21 17:57
Thanks for the replies guys.

No offence taken to asking me which way drone was facing - an obvious mistake a beginner may make!  

Hi,

Just upload your flightlog, doesn`t matter (for me) if your flyapp is on 1.2.2.
Link is in my post #4

cheers
JJB
2021-1-22
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GavinM
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JJB* Posted at 1-22 01:56
Hi,

Just upload your flightlog, doesn`t matter (for me) if your flyapp is on 1.2.2.

Just found where the flight records are filed.

Unfortunately I have flown countless short duration 2-3 minute flights (just taking off and landing or flying across my front lawn and back) to gain familiarity with the controls.  Can’t seem to identify the two flights where I had the control stick issue.

I might just wait and see if it happens again, then immediately upload the last record.
2021-1-22
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JJB*
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GavinM Posted at 1-22 06:12
Just found where the flight records are filed.

Unfortunately I have flown countless short duration 2-3 minute flights (just taking off and landing or flying across my front lawn and back) to gain familiarity with the controls.  Can’t seem to identify the two flights where I had the control stick issue.

oke, no problem.

Happy many safe landings,

cheers
JJB
2021-1-22
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knupla2
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Fly App.
General settings
Control stick
There are [I think I recall correctly] four preset modes.
Or custom lets you choose which stick mode works best for you.
2021-1-22
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Labroides
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knupla2 Posted at 1-22 10:29
Fly App.
General settings
Control stick

There are [I think I recall correctly] four preset modes.
There is no preset mode which makes the drone fly backwards when the stick is pushed and when it's pulled.
It would be impossible to fly like that.

Or custom lets you choose which stick mode works best for you.
The OP explained that it only happened a couple of times and is mostly normal, so he hasn't set a weird custom setting.

2021-1-22
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GavinM
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Hi again guys.

Well, I haven’t had a reoccurrence of the joystick issue that prompted my original post.

However I recently had a scary incident involving the same (right hand) joystick.

Fortunately I was standing in a wide open area (incidentally a private airstrip where the owner had given me permission to fly) because my Mavic Air 2 roared away backwards for 88 metres at FULL speed immediately after taking off!   

I had manually started the motors by pulling “down and in” with both sticks.

After an interval of about 5-6 seconds I pushed UP on the left hand stick to lift off.

To my consternation, as the drone rose off the pad, it began flying backwards at full speed.  Thankfully it was in Tripod mode or it would have been going even faster!

I decided to hit Return To Home to recover control.  Thankfully the drone stopped and climbed to its preset 40 metre RTH height.   Unfortunately, it then began to continue its backwards flight at full throttle for almost another 100 metres before I pushed the right stick full UP and regained manual control to fly it back.  The rest of the flight was under control.

I have reviewed the flight record for this flight and played the trip back.   It shows the sticks were pulled “down and in” to start the motors but only the left stick centralised when I let go of them. The right stick appears to have moved to full DOWN instead of back to centre.   So when I pushed UP on the left stick to start my flight I was unaware of the FULL DOWN condition of the right stick sensor. . The drone of course responded as it was being commanded by flying at full speed backwards.

My question is - can I establish from the flight record that there was a control stick malfunction (warranty claim) or is there no way of proving that I hadn’t simply held down the joystick myself?

Here is the flight record for anyone interested (my first time sharing so I hope I have done it correctly):-

https://app.airdata.com/share/wbSYnW
2021-3-8
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GaryDoug
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I see the max reverse stick plainly in the flight log. But I doubt there is any way to prove it was a fault without a hardware analysis. That being said, I do think it is a fault that involves an intermittent open circuit inside the controller. If you want, you can tell them a retired EE told you that ;-)
2021-3-8
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GavinM
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GaryDoug Posted at 3-8 20:57
I see the max reverse stick plainly in the flight log. But I doubt there is any way to prove it was a fault without a hardware analysis. That being said, I do think it is a fault that involves an intermittent open circuit inside the controller. If you want, you can tell them a retired EE told you that ;-)

Thanks Gary,

I did make a call to DJI Support on their “Australian” number - only to be talking to someone in a Philippines call centre speaking in a Filippino-American accent I could barely understand (not her fault) who only really seemed interested to know if the drone had crashed.  I told her not yet, but I’m concerned it may in future.

She lectured me about calibrating the IMU before each flight, but I really don’t think it was an IMU issue (I could be wrong).   

Personally I suspect there is an intermittent issue with the right stick - as you suggested.
2021-3-8
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JJB*
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GavinM Posted at 3-8 20:38
Hi again guys.

Well, I haven’t had a reoccurrence of the joystick issue that prompted my original post.

Hi GavinM,

As Gary already said, but now visible in a chart.....

100% stick aft from the moment you started rotors, looks like the aft stick did not return to zero after this.
But twice from 100% to 97% and back to 100%, 1s and 13s after starting motors.
In RTH still 100% aft, after engaging RTH speed drops from 11.4 m/s to zero, so RTH overuled the aft stick value.More weird input variations in the log.
See the aft stick input in the chart, my advice is to seek support from DJI !
This way you can loose your MA2, as it happens before.

Chart2, line 16 > 100% on 4 sticks to start motors, but the pitch value remains 100% after releasing sticks (wich you ofcourse did!)
cheers
JJB

analysis1.png
analysis2.png
2021-3-9
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GavinM
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JJB* Posted at 3-9 00:37
Hi GavinM,

As Gary already said, but now visible in a chart.....

Thanks JJB.

So, (excuse my ignorance) is it *not* possible to establish from the data recorded in the logs that the right hand stick (or it’s sensor) malfunctioned?

I mean, DJI could say it is quite possible that I just held the right hand stick down the whole time - even while I was selecting RTH, lol.
2021-3-9
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JJB*
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GavinM Posted at 3-9 02:43
Thanks JJB.

So, (excuse my ignorance) is it *not* possible to establish from the data recorded in the logs that the right hand stick (or it’s sensor) malfunctioned?

Hi,

Good question, ofcourse you did not hold that stick all the time aft.  But how to proof it ??
Ofcourse in a RTH your would not hold you aft stick at 100%.  Not sure what will happen if i engage RTH with 100% aft stick, i will test this out myself.
Don`t know how....i would calibrate the RC controls and make a video of that. If before calibrating the stick is set to zero afte moving around while on the display it is still at 100%  you have your evidence.

But mayby DJI can read out the DAT file and see if some error is to be found in that file.

Just start a support request.

cheers
JJB
2021-3-9
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GavinM
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JJB* Posted at 3-9 03:02
Hi,

Good question, ofcourse you did not hold that stick all the time aft.  But how to proof it ??

Yes, I think I’ll do that - to protect my ass if the same issue results in a fly away loss in the future.  I don’t have DJI Care (didn’t understand its importance until well after the first 48hours
2021-3-9
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GavinM
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I don’t know what is going on here - my replies are being cut off and only partially posted.

I commented (but it wasn’t posted): Thank you JJB for taking the time to have a look at my flight record.  Much appreciated.
2021-3-9
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JJB*
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GavinM Posted at 3-9 03:27
I don’t know what is going on here - my replies are being cut off and only partially posted.

I commented (but it wasn’t posted): Thank you JJB for taking the time to have a look at my flight record.  Much appreciated.

my pleasure

But without DJI care you still have product garanty, so start a case with DJI support.

cheers
JJB
2021-3-9
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