Mavic Pro Platinum - erratic behavior over wet road at night

[MEFfly]

Relative nooby here.

I took my MPP out last night to try to get some images of cars driving through the fog on a road by my house.

I set the drone down outside on a white plastic tote lid on my wet blacktop driveway. It was in atti mode, so i waited for it to go to GPS mode. I think the screen indicated it was in connection with 7 satellites at time of takeoff. It did however tell me that visual obstacle avoidance was non-operational due to low light, which I would expect at night, right?

I did an auto-takeoff, and the drone only lifted off to about 1 ft (instead of 3ish feet), and started flying by itself straight backward. I had to actually knock it with my hand before it would have crashed into my car. The drone was no worse for wear after its short fall to the ground (<2 ft), but the blades cut a few of my fingers before I got the drone stopped.

So I turned the drone back on, put back on the tote lid, and did another auto-takeoff. It again rose to only about 1-2 ft, but then it started acting very weird. It would not stay in one place. It was increasing and decreasing height by several feet, as well as drifting mostly side to side. Sometimes it was down to 1 ft over the the driveway. Without active adjustments using the remote, it would most definitely have flown into my house or some trees.

I then turned off the visual obstacle avoidance off, thinking it was confused by the darkness or the dark wet asphalt. It acted the same erratic way.

Turn the visual avoidance back on, then brought it back down... when it went to land, it was not a gentle smooth landing, but faster than usual, and the props did not turn off. I had to pull both joysticks down and to center to turn off the motors.

So I decided to just call it a night.

Now today, I took outside to a parking lot. It took off fine, hovered perfectly with essentially no need for active corrections. I also noted more GPS satellite connections, like 11-13


So all that to get to a few questions:

1) Is more erratic behavior usual at night?

2) Do less GPS satellite connections make it more erratic? Is there a "magic" number to shoot for?

3) Could the wet black driveway have messed us something in the guidance/obstacle avoidance?

4) Why would the drone land, but the propellers not turn off? Did the drone still think it was in the air due to wet black driveway under it?

5) Any recommended tips or tutorials for night flying to assure good control and minimize crashing?

regards,
-Mark

 

[Mossiback]

...So all that to get to a few questions:

1) Is more erratic behavior usual at night?

2) Do less GPS satellite connections make it more erratic? Is there a "magic" number to shoot for?

3) Could the wet black driveway have messed us something in the guidance/obstacle avoidance?

4) Why would the drone land, but the propellers not turn off? Did the drone still think it was in the air due to wet black driveway under it?

5) Any recommended tips or tutorials for night flying to assure good control and minimize crashing?

regards,
-Mark

1) Yes, if within a few feet of the ground. VPS does not work well in low light so it depends on GPS which could vary a few feet.

2) Yes. My "magic" number is 10 because my MP switches into GPS mode at 9.

3) I doubt if the wet driveway affects guidance/OA but the darkness and lack of solid GPS would.

4). It sounds like OA was turned off at landing or there was a problem with the ultrasonic sensors (might have some water droplets sprayed on them at takeoff?) because it should have detected the ground and landed normally. The darkness should only have affected the precision landing function. If you continued to hold the left stick down it should have shut off the motors after a couple seconds.

5) Don't know about tutorials, but the only difference in controlling it at night would be the lack of vision based OA and the reduced ability of the operator to see an obstacle in time to avoid it.

 

[g36pilot]

Agree with Mossiback and will offer opinion from a M2P guy.

1) It's less automated behavior requiring a deeper systems knowledge. The manuals are pretty weak in explaining performance boundaries and often lack cross reference to all affected systems.

2) Unsure of Sat minimum counts. 7 sounds rather light. Signal health is another determining factor. Being in ATTI mode would explain your drifting.

3) A wet surface often reflects a sensing signal rendering it unusable. Additionally, a solid black surface has no contrast for the Vision Positioning System to "lock" onto allowing drift to occur.

4) No idea, but as Mossiback mentioned. Holding the left stick all the way down should have shut off the motors once no further craft movement was sensed. I suspect disarm will not happen w/o full stick down and no aircraft movement is detected.

5) Haven't searched for night flying tips, but sure they're out there.