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Drone not responding to stick input

ioprok

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Feb 15, 2024
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Age
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Location
Switzerland
Hello all,

I have been flying a Mavic air since 2018, and in the past 2 flights I noticed 2 cases (one in each flight) where the drone did not respond to stick command to start from hover. In the last one, i pushed the forward stick 4 times and the drone didnt respond at all. When I pushed up for altitude it did and then only started responding again. all this in less than 10 seconds. The flight record in the app shows that the sticks moved but not the drone.
In the previous flight the drone was going down while hovering, and although i pushed the up, it didnt respond and continue falling, with a rate of 0.2m/s, not much but still wasnt hovering at a fixed altitude. No wind on that day, only lots of fog.

I would like to ask if anyone had such experience and maybe how you solved it. DJI said to send the drone back, check and send me the bill later, but I said no as probably the cost will be the same as buying a new.

Let me know if anyone has encountered this, I can also provide the flight record, txt file i guess you need(?).
 
hello attached, the issue is around 1:40 - 2:00 into the flight. The drone is hovering and there are 4 attempts to move forward, even with 86% the drone hardly moves.

Let me know if this is not the file.

file below as I cant load it in the post.
 
Last edited:
Some information here.
 
...the issue is around 1:40 - 2:00 into the flight. The drone is hovering and there are 4 attempts to move forward...

Let me know if this is not the file.
Most probably not the correct log... in that time span in the attached log, you flew in tripod mode, didn't use the elevator at all (Right stick forward/backwards). The achieved tilt, vertical & horizontal speed & that you only used half stick inputs corresponds pretty well with Tripod mode.

1708000152089.png
 
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Hello from the Crossroads of America ioprok


No wind on that day, only lots of fog.


Reminds of the days of flying the SPARK and the related stories of FOG that may affect the sensors to the point where it wouldn't move forward because of the obstacle (fog) and the downward sensors were affected as well.

The SPARK would think the fog is the ground and slowly try to land if down stick was applied when lowering altitude.

DJI doesn't recommend flying drones in poor weather conditions including fog.

Welcome to the Forum. :cool:

.
 
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Thanks. I had flown in fog but then the drone sat to dry in very warm condition, potentially got the problem already. Today I flew again, works like normal.
 
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Most probably not the correct log... in that time span in the attached log, you flew in tripod mode, didn't use the elevator at all (Right stick forward/backwards). The achieved tilt, vertical & horizontal speed & that you only used half stick inputs corresponds pretty well with Tripod mode.

View attachment 172643
Thank you, that was the flight record as I didnt have another for that day. maybe i missunderstood something? i did have it in tripod mode that is correct, but then switched back. I will try to record the screen and send a video with the moment. Today I flew again 3 batteries and didnt face the same, oddly enough.
 
...that was the flight record as I didnt have another for that day.
Well... in this flight you nearly never use just the elevator command alone, always combine it with at least 2 other axis inputs... like throttle & aileron/rudder. All this make it hard to match up expected tilt angels & speeds with your stick inputs.

Found a short section much later into the flight (between 598-608sec into the flight) where you only used elevator (right stick forward)... but unfortunately it's only short bursts (lasting 2-3sec each) & furthermore not full stick inputs either.

We know out from the specs for a Air 1 that in Normal mode with a full elevator input it should reach a 25 degree pitch angle & about a 8m/s speed... & with Sport mode a 35 degree angle & 19m/s... but this is with full max stick inputs.

If using only partial inputs, the GO 4 app settings for EXP comes into play... in other words, what pitch angle & speed the drone reaches with partial stick inputs depends on the EXP setting (the drones reaction to the input isn't linear). An example of the EXP settings in the GO 4 app below.

1708031278865.png

Here is the section of the flight that I found only elevator inputs...

To the left in the sat.picture I've market the path with a white arrow... this section is depicted in the chart.

White background color is Normal mode
Pink background color is Sport mode
The dashed green graph is the elevator stick command (value 10 000 is max, 0 is neutral)
The red graph is the pitch angle (Negative value=nose down, Positive=nose up)
The blue graph is the achieved ground speed

(Click on the chart to make it larger)
1708031544155.png

Nothing in the telemetry sticks out in particular... besides one tiny thing.

Have placed a chart marker at 599,8sec... right there you have a constant elevator input (but not full). We see that the drone starts to pitch down from the start of the stick input... but right there at 599,8sec it lift the nose from -9,7 to -3,1 degrees for no reason... this of course affects the acceleration & later the reached speed.

You said initially that it was foggy... & this flight was conducted in Switzerland. Was it somewhere between +5C - -20C degrees? Could the reason be prop icing..?
 
Very detailed, thank you very much for all the info. No the previous flight I had done was in heavy fog, this was very clear a bit more wind gust but nothing outside the limits.
 
Then my advice is... if this happens again you only command flight in the direction that doesn't behave, if you for instance doesn't get expected forward speed in Normal mode (in calm winds)... use only max command (elevator) for a longer time... come then back & share that log with us.

Another thing you also could try is to replace all props to a new set... the ones you have on now can maybe be slightly flattened due to some reason & doesn't create enough thrust.
 
Then my advice is... if this happens again you only command flight in the direction that doesn't behave, if you for instance doesn't get expected forward speed in Normal mode (in calm winds)... use only max command (elevator) for a longer time... come then back & share that log with us.

Another thing you also could try is to replace all props to a new set... the ones you have on now can maybe be slightly flattened due to some reason & doesn't create enough thrust.
perfect will keep an eye and do that, I will keep and reply to this post to avoid polluting the forum.
I honestly appreciate your support and effort, thank you very much!
 
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