A few days ago I was flying outside and inside a big building.First I made a shot outside and the weather became bad. Rain started, and we went inside to prepare a shot in a big hall. I would fly up in front of a accending elevator.In the hall was some light, and a reflecting piece of art (like a disco ball) wich reflected some (moving) light on the environment. The drone was still a little wet. I saw some raindrops on the body. I checked the lens and this was all dry.

First I started the drone, flew a little up and found the right position with some manouvres. I switched of the headlights to prevent reflections in the glass elevator, and I switched off obstacle avoidence, since there ware many obstacles and I would fly only up with the elevator.
Then I flew up next to the elevator to test the shot (and the accending speed I needed to follow the elevator). And at about 10M high, my mavic flew on itself forward and a bit to the right, and crashed. I am certain it was not me moving the sticks the wrong way. I did move the sticks to try to correct this by reversing, but to no avail, and the drone crashed to a wall and to the ground. Two broken legs, and a broken battery. But well... I am trying to find out what went wrong.
Is there somebody here who can see something strange in the log ? I cant find the readings of the visual positioning system, since I have a feeling the problem is there.

It is a horrible feeling if the drone does something I did not tell it to do. Now I lose my trust in this device, and that is a big problem... this is the absolute first time this happened to me. (I fly more then 7 years) with multiple drones.

I really hope somebody can shine a light on this.



Log :
https://www.phantomhelp.com/LogViewer/N7ZTK07FIITJJPS54FGX/

Best Regards,
Pepijn.

You never had enough satellites during the flight for GPS to give horizontal position holding.
Position holding would have relied on the VPS sensors.
If the floor had a suitable pattern or texture for VPS and good enough lighting, you would have had position holding.
If not, the the drone would be subject to drifting and also wouldn't have any "brakes".

As there was no GPS, we have no speed data and can't tell if it was moving in any direction or how fast.
This makes it difficult to tell exactly what happened.

The data shows you didn't touch the right stick from 1:50.3 until 2:01.5 when you pulled the stick hard back and also pushed it to the left, presumably to avoid an obstacle.
It appears that the crash impact happened at or just after 2:01.9 and the drone tumbled to the ground.

Hi, thank you for reaching out. We're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support. Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. To check the warranty period for each part, you may click this link: https://www.dji.com/service/policy. Thank you for your kind and understanding.

Hi,

Bad luck, whole flight flying in OPTI mode. VPS height indicating normal.
Speed info in the log, as in OPTI mode speed is derived from X and Y speed values.
See my chart of your data.

Vision was lost at 1m58s in the log at 6.7 mtr VPS height, while climbing to 9.1 meter.
Craft into ATTI mode.
At 2m00s height wasn`t recorded for short moment.
At that moment craft pitched down and to the right, so speeding up with no RC input.
Speed from zero to approx 3 m/s. Vision got reference back but too late....

cheers
JJB

JJB* Posted at 2-18 05:02
Hi,

Bad luck, whole flight flying in OPTI mode. VPS height indicating normal.

Thank you so much for your time to take a look, and uploading the graph chart !
you write :
"At that moment craft pitched down and to the right, so speeding up with no RC input.
Speed from zero to approx 3 m/s. Vision got reference back but too late...."

Tha'ts exectly what happened !

So if I understand correctly the OPTI mode was unable to track the surroundings, and the drone switched to ATTI, and then started to move forward, and crashed. And apparently I was to late to correct this behaviour with the stick... (this all happened within a second unfortionally).
Is it a plausible thought that the optical positioning sensor suddenly was covered by a rain drop, wich distorted the view and the ATTI mode kicked in ? Hmmm... many questions

Pepijn Posted at 2-18 06:18
Thank you so much for your time to take a look, and uploading the graph chart !
you write :
"At that moment craft pitched down and to the right, so speeding up with no RC input.

Hi Pepijn,

I have ofcourse no idea why the visual reference lost its visual....how higher how more reference is needed to 'get the picture'.
But yes, if sensor(s) are blocked by a waterdrop....yes possible.

The moment ATTI kicks in while the drone is fully stable hovering with no correction to keep it there....it will remain steady hovering. If not it will accelerate...RC response has to be really quick.

cheers
JJB

I have both the pro platinum and the mini. The mini seems to handle indoor flight (stable) better. The pro does not fare so well and I would not recommend flying it indoors. IMHO

Tony D. Posted at 3-13 08:02
I have both the pro platinum and the mini. The mini seems to handle indoor flight (stable) better. The pro does not fare so well and I would not recommend flying it indoors. IMHO

I think sensors back then have been improved hugely.

Pepijn Posted at 2-18 06:18
Thank you so much for your time to take a look, and uploading the graph chart !
you write :
"At that moment craft pitched down and to the right, so speeding up with no RC input.

Maybe rain drops but extremely unlikely as they would have to be falling up and to at about 9 metres.

The most likely issue is that the ground / Floor had no visible pattern. For the Optiflow to work it must see a pattern in the sensors. A bland floor will not support optiflow sensors. Also the sensor range is quite low. At 9 Metres it is about to cut off.

It can also be a problem if the lighting is not bright enough to recognise any pattern on the ground / floor.