Height Stability - On water and land - drifting downwards

[GeraldV]

Hi,

I posted a week or so ago about my new M2P losing height when over water and had put it down to the sensor having issues with reflections. However i have flown it 5 or 6 times and notice the same effect over land (Sand, concrete and grass). Basically when I leave the drone with no inputs from the controller it will drift downwards, typically between 10 and 30cm but has gone as far as half a meter. I notice it when flying low around 2m. I believe it is doing the same when flying higher but the gymbal negates the effect and so its difficult to see.

Within the DJI app you see the height is also registering as changing; its quite slow but noticeable. I have to apply a little lift and the drone will climb and remain stable for a while before starting to lower again. All the firmware is updated running the latest versions and compass is calibrated; no warnings on the screen.

Are there any checks or calibrations that I should run on the controller/drone to ensure no erroneous signals are being sent when nothing is touching the flight sticks?

Appreciate any help or advice.

 

[Dragonfly]

Silly to ask but need too, you have double checked in Go4 settings that all VPS sensors are turned on including in advance mode. Can be turned off after an update.
Also when Mavic is on, hold a cell phone with its volume up full next to bottom of drone and you should hear it clicking through phone, this is the ultrasonic sensors used for bottom height adjustment working. If no clicking then somthing is wrong.

 

[GeraldV]

Silly to ask but need too, you have double checked in Go4 settings that all VPS sensors are turned on including in advance mode. Can be turned off after an update.
Also when Mavic is on, hold a cell phone with its volume up full next to bottom of drone and you should hear it clicking through phone, this is the ultrasonic sensors used for bottom height adjustment working. If no clicking then somthing is wrong.

Thanks for the tips.. I am 99% sure the VPS sensors are on but will double check tonight.

 

[GeraldV]

Ok took drone out again tonight to run some tests. Can confirm the VPS sensors are all on. If I fly the drone and put my hands below it the drone lifts and hands ontop causes the drone to drop. I did the cell phone test but did not pick up anything from the mobile speakers; no clicking at all.

I took some video of the drift as it did it again this evening. The wind was very light (Ignore the superbock wind sock, its got a wire in it.. .

You can see the video here:

Is it a problem? I have the air also and have not noticed this issue with it.

 

[Chasing Light & Shadows]

Mine drifts all over the place, haven't had time yet but need to calibrate all the sensors and control sticks. Hoping that will fix it. Have you noticed that the first minute or so it flies ok and then steadily gets worse? At one point it kept drifting back towards my head and in tripod mode I had to use full stick up just to keep it in place!

 

[gnirtS]

It depends on the water. A decent disturbed surface with ripples and so on its fine.
However, a smooth, very reflective body of water mine does drift downwards 1-2m before seemingly stabilising itself. The manual does warn about this and i only see it low enough for the VPS to be used. Baro altitude only it doesnt happen.

 

[GeraldV]

Mine drifts all over the place, haven't had time yet but need to calibrate all the sensors and control sticks. Hoping that will fix it. Have you noticed that the first minute or so it flies ok and then steadily gets worse? At one point it kept drifting back towards my head and in tripod mode I had to use full stick up just to keep it in place!

That rings true for me also. Seems stable at first, fly around a bit and then it starts playing up. Will try the calibration; guess you do that throigh the dji assistant software on pc right?

 

[GeraldV]

Just spoken with DJI Support who say the issue is not normal (after watching the video) and to do an IMU calibration from the app and a controller calibration from the dji assitance app. Will do those tonight and see how it goes.

 

[Chasing Light & Shadows]

I didn't have chance to do the calibration before flying yesterday. It flew perfect for about 15 minutes and then a red box alert popped up saying "switching to backup IMU" and then it started to drift pretty much out of control as I was descending through a small gap in the trees, was a close one and had to use full stick movements to counteract. Definitely gonna calibrate before next flight! I'll keep you posted how I get on. Cheers.

 

[GeraldV]

I didn't have chance to do the calibration before flying yesterday. It flew perfect for about 15 minutes and then a red box alert popped up saying "switching to backup IMU" and then it started to drift pretty much out of control as I was descending through a small gap in the trees, was a close one and had to use full stick movements to counteract. Definitely gonna calibrate before next flight! I'll keep you posted how I get on. Cheers.

I did the full works yesterday - IMU calibration, controller calibration and the sensor calibration using the DJI assitant on the PC. (That sensor calibration is a pain in the A$$ - make sure you are using the very latest DJI assistant version). Will try a flight in the next days to see if it has improved.

 

[Chasing Light & Shadows]

Thanks for the tips and hopefully that's your drone sorted. I think I'll give the sensor calibration a miss unless the IMU calibration doesn't work. Last resort before sending it back to DJI!

 

[Chasing Light & Shadows]

I did the full works yesterday - IMU calibration, controller calibration and the sensor calibration using the DJI assitant on the PC. (That sensor calibration is a pain in the A$$ - make sure you are using the very latest DJI assistant version). Will try a flight in the next days to see if it has improved.

Seems to be working ok now, certainly a lot better but only had a couple of flights. First I calibrated the sticks and that made no difference. Calibrating the IMU is what worked.
The only slight thing I've noticed is if for example I fly to the left and then stop the drone stops and then over compensates by flying right. Which means it never actually stops in the right place, always a foot or so out of place. I can live with that though!

Did the IMU calibration fix your problem?

Cheers, D.

 

[GeraldV]

Seems to be working ok now, certainly a lot better but only had a couple of flights. First I calibrated the sticks and that made no difference. Calibrating the IMU is what worked.
The only slight thing I've noticed is if for example I fly to the left and then stop the drone stops and then over compensates by flying right. Which means it never actually stops in the right place, always a foot or so out of place. I can live with that though!

Did the IMU calibration fix your problem?

Cheers, D.

Not had chance to fly it since due to the weather.. When I do I'll report back in.

 

[noosaguy]

Not had chance to fly it since due to the weather.. When I do I'll report back in.

Any chance to test it again? I have the same problem and it's my only disappointment with my M2P.

 

[GeraldV]

Any chance to test it again? I have the same problem and it's my only disappointment with my M2P.

Not yet, weather here has been hurricane winds and rain. Hopefully the weekend will allow a window of opportunity.

 

[AMann]

Silly to ask but need too, you have double checked in Go4 settings that all VPS sensors are turned on including in advance mode. Can be turned off after an update.
Also when Mavic is on, hold a cell phone with its volume up full next to bottom of drone and you should hear it clicking through phone, this is the ultrasonic sensors used for bottom height adjustment working. If no clicking then somthing is wrong.

OP has a M2P- I thought there are no ultrasonic sensors on it, purely optical.

 

[benelot]

OP has a M2P- I thought there are no ultrasonic sensors on it, purely optical.

On the bottom and top there are.

 

[AMann]

On the bottom and top there are.

Those rounded purple windows are transducers? I thought they were IR sensors. I’m used to the older conical little ones with a screen in front of them... i have a ultrasound detector for bats, will have to check that out.

 

[GeraldV]

Seems to be working ok now, certainly a lot better but only had a couple of flights. First I calibrated the sticks and that made no difference. Calibrating the IMU is what worked.
The only slight thing I've noticed is if for example I fly to the left and then stop the drone stops and then over compensates by flying right. Which means it never actually stops in the right place, always a foot or so out of place. I can live with that though!

Did the IMU calibration fix your problem?

Cheers, D.

Took the drone out today and didn’t appear to have any issues. Have a trip planned next week to Poland with their great drone freedoms so hopefully will have the opportunity to do more tests. Initial impressions are good!

 

[benelot]

Those rounded purple windows are transducers? I thought they were IR sensors. I’m used to the older conical little ones with a screen in front of them... i have a ultrasound detector for bats, will have to check that out.

You're actually right, sorry. IR only! Wouldn't make sense to have additional stereo cameras on the bottom otherwise.