Auto-landing when descending below take-off altitude.

[rvt3]

I would just like to add my own personal experience with a similar issue flying in the gorges and valleys of hawaii recently where the same thing happened repeatedly while I was variously 1200-1700ft above the valley floor, descending into it. it 100% came down to rapid changes humidity and water condensation in the air. the sensors perform very poorly in the kind of high humidity and condensation you find around waterfalls and rapidly changing micro climates like cloud rainforests in hawaii.

 

[Meta4]

I would just like to add my own personal experience with a similar issue flying in the gorges and valleys of hawaii recently where the same thing happened repeatedly while I was variously 1200-1700ft above the valley floor, descending into it. it 100% came down to rapid changes humidity and water condensation in the air. the sensors perform very poorly in the kind of high humidity and condensation you find around waterfalls and rapidly changing micro climates like cloud rainforests in hawaii.

What did the sensor data show?

 

[rvt3]

What did the sensor data show?

the exact same thing as shown above, crazy flatline plateaus in the readout. I thought it was because some moisture had actually condensed on the sensor. but when the drone landed, there was never any dew on the drone. I resolved to fly without landing protection and downward vision systems enabled and had no further issues.

 

[Meta4]

the exact same thing as shown above, crazy flatline plateaus in the readout. I thought it was because some moisture had actually condensed on the sensor. but when the drone landed, there was never any dew on the drone. I resolved to fly without landing protection and downward vision systems enabled and had no further issues.

I was curious about the VPS data.
Was it giving false readings indicating the drone was close to the ground even though it was high up?

 

[rvt3]

I was curious about the VPS data.
Was it giving false readings indicating the drone was close to the ground even though it was high up?

Yes, it would snap from a reading in the hundreds of feet, to a reading of -2 or -3 ft. It would then attempt to initiate autoland because i was left stick down, descending into the valley.

 

[Meta4]

Water droplets and mist are generally quite transparent in the infrared spectrum due to the wavelength being longer relative to the particle size, but I guess that cannot be ruled out without testing. Note that the VPS height for the flight posted was pretty much exactly zero for the entire duration - to me that suggests a sensor fault.

The Downward Sensor Error warning message that popped up twice is strongly suggesting that.
I haven't seen that with cases of real physical obstructions like gimbal guards.
This time the flight controller recognised a problem with the VPS data.

 

[ManBearPig1989]

Yes, it would snap from a reading in the hundreds of feet, to a reading of -2 or -3 ft. It would then attempt to initiate autoland because i was left stick down, descending into the valley.

That sounds extremely similar to what im getting. What I found strange is that the VPS sensor seems to deal just fine ascending to high altitudes and up and down a mountain ridge yet seems to quickly become dysfunctional in valleys with waterfalls. Im still not really confident that its not some sort of faulty sensor though.

 

[lenal]

Was there water vapor or mist around the drone? others have had issues with fog which is similar to mist.
Also waterfalls often have a strong updraft so the drone can interpret the air resistance as being close to the ground? did you notice an updraft at these falls?

 

[sar104]

Was there water vapor or mist around the drone? others have had issues with fog which is similar to mist.
Also waterfalls often have a strong updraft so the drone can interpret the air resistance as being close to the ground? did you notice an updraft at these falls?

The problem was a faulty downward sensor leading to the FC erroneously detecting that it was about to land, not a failure to descend. The only unknown here is the actual nature of the fault.

 

[aerialodyssey]

I've had the same issue twice now. Each time was over water. I'm going to try what @rvt3 did in his settings.