My drone started drifting, hit a tree & fell into a river. I've got a new drone now, but need to know what went wrong, so it doesn't happen again.

It was sunny, warm, dry, not windy, I was hovering approx 3m above reflective (still) water when it happened.

I tried to move it in the other direction, but it didn't respond.

Could this be a bug?

I've posted a link to this question in another forum, with flight log, so you can see exactly what went wrong.

https://mavicpilots.com/threads/mini-3-pro-started-drifting-why.137767/#post-1553397

Hi, ReggieNoo. Thanks for reaching out, and we're sorry to read about the accident. Just to confirm, did you submit a case and received a replacement or warranty service from DJI? We'll be waiting for your update. Thank you.

https://www.phantomhelp.com/logviewer/12KF2PL007641E5QM4UI/

HI,

Had a look at your flight.

At the end your Mini3Pro was in active track.
What was it tracking ?

From a steady hover into Activetrack ; drone started to move away...tracking but what ?

cheers
JJB

JJB* Posted at 5-20 00:08
HI,

Had a look at your flight.
[Image]

I saw that, but absolutely didn't enter active track, unless I did by mistake. I didn't have subject scanning turned on either & it was a really still day.

Their were many pieces of foam moving slowly down the river (not towards the bank), so I'm confused why it drifted that way, even if A. T. were activated.

DJI Tony Posted at 5-19 23:21
Hi, ReggieNoo. Thanks for reaching out, and we're sorry to read about the accident. Just to confirm, did you submit a case and received a replacement or warranty service from DJI? We'll be waiting for your update. Thank you.

I claimed on insurance, thanks.

ReggieNoo Posted at 5-20 00:18
I saw that, but absolutely didn't enter active track, unless I did by mistake. I didn't have subject scanning turned on either & it was a really still day.

Their were many pieces of foam moving slowly down the river (not towards the bank), so I'm confused why it drifted that way, even if A. T. were activated.

Hi,

I have no clue how ActiveTrack became active....but it did track and moved away.
Touching the screen will start the AT on the screen, have to check if screen touching once is enough to show AT in the log.

IMO your drone wasn`t too low (7 meters IR height)  above the water for getting confused by streaming water or moving foam.

BTW  your RC mode switch at start at mode C, but drones always starts in N mode despite position of this switch.
cheers
JJB

JJB* Posted at 5-20 00:26
Hi,

I have no clue how ActiveTrack became active....but it did track and moved away.

Only if subject scanning is on, no?
And when in active track, one can still move the drone using the sticks, so why didn't it move, with the stick hard left?

ReggieNoo Posted at 5-20 00:48
Only if subject scanning is on, no?
And when in active track, one can still move the drone using the sticks, so why didn't it move, with the stick hard left?

Nope,

If subject scanning is OFF then touching and slide on the screen select a object.
Active tracking SpotLight is then active.

But before that you have to close a screen prompt, wich you normally do as it blocks the view on the screen. So guess you saw this and was not aware that Spotlight mode was active.

Your left roll input had effect, only to late to stop the motion before impact.




cheers
JJB

Come JJB*... Your head is not that big....

JJB* Posted at 5-20 00:26
Hi,

I have no clue how ActiveTrack became active....but it did track and moved away.

Would the DAT have any clues about how or why "ActiveTrack" became active?

ReggieNoo, is the DAT available?

Sean-bumble-bee Posted at 5-20 02:00
Would the DAT have any clues about how or why "ActiveTrack" became active?

ReggieNoo, is the DAT available?

No it's not. Somebody else asked me to check that.

JJB* Posted at 5-20 01:04
Nope,

If subject scanning is OFF then touching and slide on the screen select a object.

I didn't engage active track & cancel the warning. I was over a river, with tree branches close, I'd NEVER EVER use active track in that situation.

Hence me thinking it could be a bug.

ReggieNoo Posted at 5-20 02:38
I didn't engage active track & cancel the warning. I was over a river, with tree branches close, I'd NEVER EVER use active track in that situation.

Hence me thinking it could be a bug.

Oke,  just wait and see what DJI will inform you....

In your "AT" drone moved to the right and yawed left, this is spotlight behaviour.
Only in spotlight Drone should stay at same hover postion.
Must have something to do with floating foam.

Never saw or read about AT became active without pilot input to do so.
But ofcourse you are correct in knowing that you did not activate AT.

cheers
JJB

ReggieNoo Posted at 5-20 02:34
No it's not. Somebody else asked me to check that.

That's a pity.

Active tracking can be engaged accidentally when touching the screen, have done it myself but I noticed in time and cancelled it.

ReggieNoo Posted at 5-20 02:38
I didn't engage active track & cancel the warning. I was over a river, with tree branches close, I'd NEVER EVER use active track in that situation.

Hence me thinking it could be a bug.

Just remember for future there is an emergency "RTH/Pause" button on the controller, anytime anything going wrong by mistake or aircraft starts doing anything on it own you can either press that button to pause its flight (that will cancel active tracking) or you can do RTH by pressing & holding for 3 sec the same button that will cancel all things & make the ascend to RTH height set & return home.

Bashy Posted at 5-20 17:41
Active tracking can be engaged accidentally when touching the screen, have done it myself but I noticed in time and cancelled it.

But even if you engage it accidentally there is a GO button which needs to be pressed after that only then it start the orbiting, isn't it so?

Ranjan Posted at 5-20 19:01
But even if you engage it accidentally there is a GO button which needs to be pressed after that only then it start the orbiting, isn't it so?

Not got a clue to be fair, i dont use active track, all i know is that i have activated it in the past by accident.

If it cannot be started accidentally then it had to have been purposely done

Any chance that the GPS HDOP was low and it used optiflow and tracked the foam?

bjr981s Posted at 5-21 03:21
Any chance that the GPS HDOP was low and it used optiflow and tracked the foam?

Could you explain "HDOP" and "optiflow"?

Ranjan Posted at 5-20 19:01
But even if you engage it accidentally there is a GO button which needs to be pressed after that only then it start the orbiting, isn't it so?

not the default spotlight, no need to press the red start button.

Sean-bumble-bee Posted at 5-21 05:47
Could you explain "HDOP" and "optiflow"?

HDOP and VDOP are Horizontal Degree of Precision and Vertical Degree of Position.

In other words how good the GPS lock is. It cannot be determined by the number of sats in your lock only by the HDOP in the flight controller. You may have many sats but in bad positions in the sky. Like all in the same direction. eg I get this if I am flying from the verandah on at my house. As the house blocks 180 degrees of sat coverage.

In drones VDOP is ignored as it is not accurate enough and a variometer is used. (Barometric air pressure sensor)

Ever wonder given that Sat lock is only good to about 6 feet, and why the drone has such a steady hover? And why it is so steady when you fly indoors without a sat GPS lock?

Those 2 little sensors on the bottom of the drone are for optiflow (optiflow is a generic term for visual tracking) The sensors detect a pattern and lock to that pattern. Till the drone is commanded to move elsewhere.

Now the optiflow is used at low level and then switches to GPS as it ascends. That allows the most precise blend of the 2 technologies. I believe the transition point is about 30 feet.

Now if you were hovering over foam below 30 feet it would recognise the foam as the pattern and move with it.

Hope this helps.

"Hope this helps."
Thanks it does, though in connection with visual position holding sensors the term I have seen used for your "optiflow" is "VPS".

bjr981s Posted at 5-24 06:41
HDOP and VDOP are Horizontal Degree of Precision and Vertical Degree of Position.

In other words how good the GPS lock is. It cannot be determined by the number of sats in your lock only by the HDOP in the flight controller. You may have many sats but in bad positions in the sky. Like all in the same direction. eg I get this if I am flying from the verandah on at my house. As the house blocks 180 degrees of sat coverage.

Hope this helps

Personally i never read about OptiFlow. OPTI mode was used few years ago for flying without GPS lock but no ATTI mode as the drone was hover stable thanks to the Vision system.

Within Downward vision range the sensors are an aid to hover stabiliy done by the the GPS positioning.
A GPS lock is not 'swicthed off' at low heights and get active again when the drone gets out of the vision range.

Low hovering above streaming water is or can be tricky, it is a combination is the IR sensor measuring height yes / no / yes etc and GPS stabilty 'ruined' by Vision tracking streaming water.

cheers
JJB