Urgent Help required.Returning to home issues with Dji mavic Pro

[Simmo]

Duuno! Its in meters, and I cant find anything else that it corrolates to. I wonder if @msinger can enlighten us?

 

[MavicCF]

Lol, we need an expert!

 

[laurens23]

Lol, we need an expert!

the 1000m is the local elevation.

 

[BudWalker]

This is quite the puzzler. I don't know the answer but just a couple of things I've observed.
HOME:height[m] is the elevation of the HP in meters
General:goHomeStatus shows that the Mavic aligned itself and then switched to cruise mode but only briefly. Normally the Mavic would remain in cruise mode until it reached the HP. In this case the cruise mode lasted all of 0.2 secs. Don't know why though.

 

[Simmo]

Thankyou so much for replying @BudWalker
Do you think that the max ceiling and rth alt being the same, confused the FC? Being that numerically, they had identical settings, but realistically, the AC would be moving around, hence mathematically, nothing was correct??

 

[BudWalker]

Thankyou so much for replying @BudWalker
Do you think that the max ceiling and rth alt being the same, confused the FC? Being that numerically, they had identical settings, but realistically, the AC would be moving around, hence mathematically, nothing was correct??

Dunno. Certainly sounds plausible. That would be easy enough to test. It would also be interesting to see what happens if the RTH height was set above the max ceiling height.

 

[MavicCF]

This is quite the puzzler. I don't know the answer but just a couple of things I've observed.
HOME:height[m] is the elevation of the HP in meters
General:goHomeStatus shows that the Mavic aligned itself and then switched to cruise mode but only briefly. Normally the Mavic would remain in cruise mode until it reached the HP. In this case the cruise mode lasted all of 0.2 secs. Don't know why though.
View attachment 33640

I did see the cruise come on then off, but yeah, nothing else lines up with it. So you said the Home_height m was the HP elevation, I always thought the HP should be set as zero and the altitud goes up or down relative to it. Am I misunderstanding this (pretty sure I am)? As I understand everything now, the home point was being recorded as 1000m up in the air, the AC would try climb 70m above the home point (thus1070m) for RTH, however as the max height is 70m so it would hit that and stop. Am I understanding that as the current guess as the problem or am I off?

 

[BudWalker]

I did see the cruise come on then off, but yeah, nothing else lines up with it. So you said the Home_height m was the HP elevation, I always thought the HP should be set as zero and the altitud goes up or down relative to it. Am I misunderstanding this (pretty sure I am)? As I understand everything now, the home point was being recorded as 1000m up in the air, the AC would try climb 70m above the home point (thus1070m) for RTH, however as the max height is 70m so it would hit that and stop. Am I understanding that as the current guess as the problem or am I off?

HOME:goHomeHeight is the signal you're thinking of. It's relative to the Home Point elevation. In this case it's set to 70 meters so the RTH will be at or above 70 meters above the HP. Except, maybe in this case, it won't because the max height is also set to 70 (above take off).

HOME:height[m] is the Home Point elevation obtained from the barometer. There is yet another Home Point elevation that can be seen in the .DAT. It's the home point elevation + 20 meters. I suspect that's to insure that a decrease in barometric pressure during flight won't cause the AC to fly into the ground.

 

[MavicCF]

HOME:goHomeHeight is the signal you're thinking of. It's relative to the Home Point elevation. In this case it's set to 70 meters so the RTH will be at or above 70 meters above the HP. Except, maybe in this case, it won't because the max height is also set to 70 (above take off).

HOME:height[m] is the Home Point elevation obtained from the barometer. There is yet another Home Point elevation that can be seen in the .DAT. It's the home point elevation + 20 meters. I suspect that's to insure that a decrease in barometric pressure during flight won't cause the AC to fly into the ground.

Am I correct in my assumption that the home point is being set at 1000m? That is the part I don't understand. Is that 1000m above sea level?

 

[BudWalker]

Am I correct in my assumption that the home point is being set at 1000m? That is the part I don't understand. Is that 1000m above sea level?

Yes, the 1000m is above sea level. But, it's not above Mean Sea Level which won't change for a given location. The HOME:height[m] value will be close to height above MSL but will be different depending on the barometric pressure and temperature (and maybe humidity?). If you use GoogleEarth you'll see that the elevation at the launch site was 996m; i.e. at launch the barometric pressure was little higher than normal.

The altitude used for RTH purposes is based on the barometer. In this case if the RTH goHomeHeight was set to 30 meters and the Mavic had to ascend to get to the goHomeHeight then the Mavic would have flown home at 1030m as measured by the barometer.

 

[MavicCF]

Yes, the 1000m is above sea level. But, it's not above Mean Sea Level which won't change for a given location. The HOME:height[m] value will be close to height above MSL but will be different depending on the barometric pressure and temperature (and maybe humidity?). If you use GoogleEarth you'll see that the elevation at the launch site was 996m; i.e. at launch the barometric pressure was little higher than normal.

The altitude used for RTH purposes is based on the barometer. In this case if the RTH goHomeHeight was set to 30 meters and the Mavic had to ascend to get to the goHomeHeight then the Mavic would have flown home at 1030m as measured by the barometer.

Okay, that makes sense. I was totally confused 'cause I wasn't sure if that altitude was above sea level or not. Thanks for clearing it up. I'm going to go try setting my max altitude and RTH settings as the same value and see what happens.-CF

 

[MavicCF]

Well just did a quick flight with both RTH and Max Altitude set to 70m I flew it out a little ways and hit RTH, it went up, gave me a "maximum flight altitude reached" notice and continued RTH as usual. I canseled the landing and tried it again with no problems with the RTH. I'm sure there could have been other factors going on with the OP's AC, but I had no problem with both settings being set to the same value.

 

[Simmo]

Thanks for the test. Can you try setting ceiling at say 50 mtrs and RTH at 60??

 

[MavicCF]

Thanks for the test. Can you try setting ceiling at say 50 mtrs and RTH at 60??

The app won't allow RTH height to be set above the maximum flight altitude.

 

[Simmo]

Ahh cool. Thanks.

 

[MavicCF]

Does this put us back to the drawing board?

 

[Simmo]

Hehe looks like it!

 

[MavicCF]

Hehe looks like it!

Although the OP haven't been on in like 11 days soo...

 

[Simmo]

So much for urgent help required!!

 

[dennyc39]

That could be why or there could be dirty sensors or something blocking them.

Hard for me to see how a blocked sensor could affect RTH function; However, in software, perhaps things like that are possible.