RTH and Climbed Unexpectedly

[ddodell]

Just started flying my new Mavic 3 this weekend, and testing out various functions. I always fly over unpopulated open desert to minimize any risks.

Trying the new RTH and the drone started at 135 feet vertically. About 2 minutes in, it start climbing unexpectedly ( this is desert nothing in the way) ... ascending to 395 ft very quickly ... kept saying messages about "Aircraft will ascend to RTH altitude before returning to Home Point (Code: 3203604) (repeated 5 times)" which is set to 105 feet, which was below my starting point height ... switched to sport mode to gain control, and flew it back manually.

Logs below ... problems started at 6m 51s in ... up to 7m 22s when I took control back over ... anyone see any reason for the sudden climb?

Log Link

KML view of sudden climb

 

[MAvic_South_Oz]

This'll be interesting, I didn't have chance to check the basic Phantomhelp info, but any depth analysis you should reveal any anomalies.

I was interested though, are you using mode 1 or 3 for controller sticks ?
Very unusual to see this, usually default mode 2 is used for drone flight.

edit grammar !

 

[ddodell]

I use Mode 3 ... I'm left handed and it feels more natural to me. I looked through the logs, and didn't see anything abnormal, but I'm not an expert in this.

 

[MAvic_South_Oz]

I use Mode 3 ... I'm left handed and it feels more natural to me. I looked through the logs, and didn't see anything abnormal, but I'm not an expert in this.

Ah, no probs.
Strange no one has popped by for a look, usually the logs would be posted in the crash section, but if @slup @sar104 or one of the other regular experts on the logs / programmes.

 

[slup]

... anyone see any reason for the sudden climb?

Here below on the sat picture it's clear that your return path was in a direct southerly direction ...



According to the the log this flight was done slightly after 3PM ... which would mean that the sun would have been positioned just in front of & to the right of the craft on the way back, which is confirmed by the shadows from this photo included in the log where your M3 was furthest away from HP & was about to turn 180 degrees in order to fly back.



In below chart you have all relevant telemetry data ... the chart have been zoomed to the position where the ascend starts for the first time at 411,8sec ... covers the ascend step wise, to the point just after you cancel the RTH & went into APAS supported N-mode again, manually taking over.

Pink background=RTH
Blue background=APAS supported N-mode

Red graph=height above HP
Dark green graph=set RTH height
Purple graph=your throttle command (mode3) (value 1024=neutral stick)
Yellow graph=your elevator command (mode 3) (value 1024=neutral stick)
Black graph=Heading speed
Bright green graph=Zspeed (vertical speed where positive value is descend & negative is ascend)

(Click on the chart to make it larger)


It's clear that something brakes the M3 at 411,8sec ... the heading speed goes to 0mph, then it accelerates forward, stops again ... and ascend in 2 steps then tries to go forward again, but stops. All this just repeats until you cancel the RTH. Your M3 definitely behaves as it sees an obstacle in it's way ... which most probably is the low bright sun.

We have seen this with taking the sun as an obstacle & trying to ascend over it numerous times here at the forum ... not only from M3's but from other models also.

 

[Ralph thompson]

But the sun is to the side, maybe 45 deg off its flight path, not directly on its nose. And yet it still sees it as an obstacle in front. How bizarre.

 

[MAvic_South_Oz]

But the sun is to the side, maybe 45 deg off its flight path, not directly on its nose. And yet it still sees it as an obstacle in front. How bizarre.

Most forward sensors on previous DJI drones do see the sun as an obstacle, but it is usually fairly straight on.
The M3 sensors are however quite different to previous models it seems, more advanced (??!!), and reportedly been making some flight erratic.
Try same flight / sun directions closer by, if it does it again try with sensors off, or pop it into sports mode (turns of OA) and see if it is ok to fly that direction.
You might also turning 90 degrees away from the sun, or even backwards to check.
Not sure if other direction sensors might also be an issue.