Hello...  I was flying over concrete in my backyard and my drone started acting weird.  Smart controler was giving me errors about air space restriction that should'nt have happened.  I do live near an air port, but the max alitutde is 150ft.  When the errors started happening, i went to go land and the drone popped up some and then did a hard land.  It didn't crash, but did land really hard from 3-4 ft in the air.  I restarted the drone and controler, it did the same hard landing.  Could this be an IMU issue and calibration is needed?  

Had you flown and landed safely before from this same concrete area? Asking this as concrete can having reinforcing iron built in for strength. This can lead to erratic readings by the sensors and IMU..

Marty Markoe Posted at 3-21 03:34
Had you flown and landed safely before from this same concrete area? Asking this as concrete can having reinforcing iron built in for strength. This can lead to erratic readings by the sensors and IMU..

Yes I have.  I never did calibrate the IMU before.  Wasn't educated with the IMU until I did some research.  I do take off and land from the concrete patio in my back yard all the time.

If you land your craft yourself, and the bottom sensor doesn`t see ground (VPS height) than it will land as you describe

If you like post your flightlog for this flight > using > https://www.phantomhelp.com/LogViewer/Upload/

Concrete etc with iron in it.....will sometimes do funny things with the compass, nothing else....

cheers
JJB

JJB* Posted at 3-21 03:51
If you land your craft yourself, and the bottom sensor doesn`t see ground (VPS height) than it will land as you describe

If you like post your flightlog for this flight > using > https://www.phantomhelp.com/LogViewer/Upload/

JJB,

Do i go to this url on the smart controller?  "if you land he aircraft yourself."  What do you mean?  How does it get put into this "land yourself mode?"  First time every it's happened.  Could it be an IMU issue?

pauly whitehead Posted at 3-21 04:01
JJB,

Do i go to this url on the smart controller?  "if you land he aircraft yourself."  What do you mean?  How does it get put into this "land yourself mode?"  First time every it's happened.  Could it be an IMU issue?

Hi,

A normal landing is where you are on the controls...so  bring craft low in hover and 100% down to go into a landing.  Because the height sensor is measuring height, it will be a controlled smooth landing.

In the SC are the flightlogs saved in a map,  i do not have SC myself but as is it Android...find a map DJI and a sub-map FlightRecords.

cheers
JJB

JJB* Posted at 3-21 04:29
Hi,

A normal landing is where you are on the controls...so  bring craft low in hover and 100% down to go into a landing.  Because the height sensor is measuring height, it will be a controlled smooth landing.

1st flight

https://www.phantomhelp.com/LogViewer/MTI2JMQNH5BRICAE32Z6
2nd flight
https://www.phantomhelp.com/LogViewer/PLALLEI7KW3BK32X5TRP

Hopefully you can assist and solve my issue JJB.  Thank you!

pauly whitehead Posted at 3-21 05:08
1st flight

https://www.phantomhelp.com/LogViewer/MTI2JMQNH5BRICAE32Z6

Hi,

Indeed, in both flights VPS height did not measured height.
So no control landing possible.



cheers
JJB

JJB* Posted at 3-21 06:26
Hi,

Indeed, in both flights VPS height did not measured height.

JJB, you're a bloodhound!  Can you offer me some pointers on how to avoid this for next time?  

I did a screen calibration using the dji assist application.  Below is my fight log test in the front yard.

https://www.phantomhelp.com/LogViewer/25PWYYYIXGJMXOI9ID60/

pauly whitehead Posted at 3-21 06:53
JJB, you're a bloodhound!  Can you offer me some pointers on how to avoid this for next time?

Just my $.02. Try using a landing pad. If the concrete is too uniform in apperance I am guessing it could mess up the landing.

BTW: I doubt that rebar in the concrete is the problem becaouse typically a patio slab will not nrrd rebar.

NightThunder Posted at 3-21 08:15
Just my $.02. Try using a landing pad. If the concrete is too uniform in apperance I am guessing it could mess up the landing.

BTW: I doubt that rebar in the concrete is the problem becaouse typically a patio slab will not nrrd rebar.

Thank you.  I recall the landing light not coming on as well.  This is not the fight time I've flown in my backyard and landing on the concrete.  Normally the bottom light comes on when it takes off if its too dark, but this time it didn't.  Maybe it just needed a calibration?  

pauly whitehead Posted at 3-21 08:02
I did a screen calibration using the dji assist application.  Below is my fight log test in the front yard.

https://www.phantomhelp.com/LogViewer/25PWYYYIXGJMXOI9ID60/

Hi,

In this flight VPS bottom sensor measured height all the time.

Try to fly out of Height range for the bottom sensor, back into range again.

It is easy to check in flight if the VPS sensor is working...
Hover at 20 meters (60 feet), 100% down and keep 100% down all the time
Notice that your drone will stop descending at approx  0.6 meter height (even with 100% down stick)
After short moment at 0.6 meter it will perform a controlled autolanding smoothly !

( if if does not stop at 0.6 meter, just pull up! )
I have no explantion why it did not see the ground in the previous flights, if it sees it at takeoff ; it must see it again at landing....

cheers
JJB

pauly whitehead Posted at 3-21 06:53
JJB, you're a bloodhound!  Can you offer me some pointers on how to avoid this for next time?

i interpretet calling me a 'bloodhoud' as a compliment....  

JJB* Posted at 3-21 08:29
i interpretet calling me a 'bloodhoud' as a compliment....

I agree with JJB*. You are indeed a blood hound and it is a very nice compliment! I am sure the whole community in this forum appreciates your help!

NightThunder Posted at 3-21 08:44
I agree with JJB*. You are indeed a blood hound and it is a very nice compliment! I am sure the whole community in this forum appreciates your help!

When I got my Dji Mini 2 and did some searching in the forum, JJB was always helping others solve problems.  I never knew I'd be one of those same members.  JJP I can't appreciate you enough.  

@JJP*
If I turn VPS off like it suggests when flying over water and forget to turn them back on, will it have that hard landing when I go back to the ground?  Does VPS need to be turned on at al times to land softly?

I'm going to do a test in my front & back yard with VPS on from 30m high as you suggested.  I will be reporting back soon.  Thank you!

JJB* Posted at 3-21 08:24
Hi,

In this flight VPS bottom sensor measured height all the time.

1st test - Front Yard 1 of 2:
https://www.phantomhelp.com/LogViewer/R649OZCVMHXZNPWM8ELD

2nd test - Front Yard 2 of 2:
https://www.phantomhelp.com/LogViewer/IAM2F3VODMGSETFFZI37

3rd test - Back Yard 1 of 2:
https://www.phantomhelp.com/LogViewer/KUZ4GN7PF5STFDRG02G8

4th test - Back Yard 2 of 2:
https://www.phantomhelp.com/LogViewer/FFOOC8WAAQIEBXH0WN5S

The drone was in P mode the whole time.  I also had vps on in the settings.  Do you think the calibrating did the trick?  If i turned vps off, would it still land OK?  Thank you!

Here is a test I did at sunset in my back yard.  The light didn't turn on automatically when I landed and I believe it was hard enough to trigger it.  What triggers the bottom light when it's on auto?  

Flight record is below.  Thank you!

https://www.phantomhelp.com/LogViewer/WN9CV5VG5R0EG2IVDVQG

pauly whitehead Posted at 3-21 12:44
When I got my Dji Mini 2 and did some searching in the forum, JJB was always helping others solve problems.  I never knew I'd be one of those same members.  JJP I can't appreciate you enough.  

@JJP*

Hi pauly,

Visual system has lots of sensors on a MP2, In sport mode the OA is disabled but not the bottom sensor for determine height above surface belows the drone.

Disabling VPS will not, afaik, disable the bottem height sensor.
Easy to check, in Sport mode or disabled VPS hover at 0,5 - 0,6 meter and see if your drone is landing automatically after short 100% down stick. (during this landing you can have stick all neutral, laning will continue)

When you see in PH "forcelanding" : this is the automated landing after short 100% stick down.

Be carefull low flying over water....if flying at 0.5 meter  [ yes forward speed flying! in will forceland as well ] and you want to lower your craft with 100% stick down it will enter this type of landing, only way to cancel = UP stick quickly!  

About the light:

cheers
JJB

pauly whitehead Posted at 3-21 13:21
1st test - Front Yard 1 of 2:
https://www.phantomhelp.com/LogViewer/R649OZCVMHXZNPWM8ELD

Did not checked 4 logs....

But it does work OK.

VPS height measures/indicates at the end flying into its range.
See your craft going down on 100% down stick, see the vertical speed decreases at the end before entering a forcelanding.

In the number chart, check 100% down stick at VPS height 0.5 - 0.6 ; this way your commanded a landing, stick to zero :  landing automatically and smoothly. *
* as said; flying low over water doing this to go even bit lower...some users lost their drone like this > into forcelanding not aware of this > splash!

cheers
JJB

JJB* Posted at 3-21 23:44
Did not checked 4 logs....

But it does work OK.

JJB:

So it looks like everything is working normally now?  Are you able to determine why the bottom sensors bugged and the hard land happening?  Could it have been the calibration that fixed it?  I also used the DJI assist to do a firmware refresh as well.  Is it worth sending in to DJI to do a check over?  Do you recommend any other test?  Thanks for helping!

pauly whitehead Posted at 3-22 01:36
JJB:

So it looks like everything is working normally now?  Are you able to determine why the bottom sensors bugged and the hard land happening?  Could it have been the calibration that fixed it?  I also used the DJI assist to do a firmware refresh as well.  Is it worth sending in to DJI to do a check over?  Do you recommend any other test?  Thanks for helping!

Hi,

If in 5 flights the height sensor works normally, tested and oke..  Just keep it in mind what have happend.

Plus it is so easy to check after take-off if it is working, just hover low at 0.5 meter and notice that it will not go down direct after 100% down RC input., after short delay it will go into forcelanding. Pull  UP and start a happy flight.  99% of my flights i end my flights witj my drone in the hover in front of me, wait few seconds, and land manually so i notice always if height sensor is working or not at landing.

Difficult to say what made it working normally again, always good to do all of some calibrations, if performed oke ofcourse.
* all DJI calibrations can be done for eacht flight; totally useless ofcourse but calibration never harms a drone.
BUT carefull for the compass calibration!: only a good performed compass calibration does not harm a drone, if done not correctly if may end in a compass/yaw fly-away in flight.

So > happy flying and many happy landings!

cheers
JJB

JJB* Posted at 3-22 03:11
Hi,

If in 5 flights the height sensor works normally, tested and oke..  Just keep it in mind what have happend.

Compass calibration is the old school way of doing things in the past, right?  I just did a YouTube search and I can see exactly what you're saying!  I did a sunrise flight this morning in my front yard and everything seems to be working normally.  Thank you!

pauly whitehead Posted at 3-22 03:47
Compass calibration is the old school way of doing things in the past, right?  I just did a YouTube search and I can see exactly what you're saying!  I did a sunrise flight this morning in my front yard and everything seems to be working normally.  Thank you!

[view_image]

Nice picture, sun colour is great!

Do enjoy flying!

cheers
JJB

JJB* Posted at 3-22 06:51
Nice picture, sun colour is great!

Do enjoy flying!

Thanks again for all of your help!  Here is the sunset from this evening.