minimum altitude

keat63 · May 17, 2021

Mavic Pro:

I'm still learning how to fly the mavic safely, what it can and can't do.
Yesterday (in a safe area) I flew at an altitude of about 6 feet, just to see if the mavic would maintain this altitude, however, I could see that it was slowly getting closer to the ground.
At what point would it have stopped descending, or would it have just grounded. ??
In the Go4 app there's a setting for maximum altitude, what about a minimum altitude ?

DoomMeister · May 17, 2021

keat63 said:
Mavic Pro:

I'm still learning how to fly the mavic safely, what it can and can't do.
Yesterday (in a safe area) I flew at an altitude of about 6 feet, just to see if the mavic would maintain this altitude, however, I could see that it was slowly getting closer to the ground.
At what point would it have stopped descending, or would it have just grounded. ??
In the Go4 app there's a setting for maximum altitude, what about a minimum altitude ?

Did the telemetry show that it was getting lower or was that a visual perception? As the aircraft moves away parallax makes it appear to get closer to the ground. You see the same effect with railroad tracks, just picture them on their side and it will make sense to you.

Gagey52 · May 17, 2021

No keat63, no minimum.
Regards

keat63 · May 17, 2021

I guess it could have been visual perception, maybe the ground was getting closer, rather than the mavic descending. It's difficult to say for sure.
As I'm still learning, I spend 99.9999% of my time watching the drone, not looking at the data.

Something for to investigate further the next time i'm out.

THE CYBORG · May 17, 2021

It is also possible that the ground wasn’t level therefore rising up to the drone as you flew forward.

slup · May 17, 2021

keat63 said:
...the mavic would maintain this altitude, however, I could see that it was slowly getting closer to the ground.
At what point would it have stopped descending, or would it have just grounded. ??

Your Mavic Pro have the "Terrain Follow Mode" ... that will give you a possibility to dial in a VPS height & then the Mavic will keep that height from the ground beneath. This function works going up hill only ... not down hill.

Check out this mode further here for instance:

Without using this mode your Mavic Pro will likely crash into the ground if the ground rises ... all depending on how fast you're flying & how fast the ground rises.

In my early days, testing out Active track with my Mavic Air 1 I was lucky ... was filming me & my wife hiking up a gravel road in Active track. Started out on 2,7m height & we started to walk. The road was first slightly going down hill ... then up hill.

The Mavic Air nicely followed down hill & kept us framed equally ... but then the road started to go up & the the height to ground beneath the drone got smaller & smaller. Eventually the drone stopped suddenly.

Here you have the short walk in 3 cuts ... note the initial framing in the first cut, then a bit lower camera angle in the second ... & in the third cut the drone stops just 0,6m from ground & refuses to continue.

Looking into the log just there when the drone stopped doesn't immediately reveal why it stopped ... the log says according to the black graph that it's near ground ... the red barometric height was constant (negative as it followed down hill initially). The blue ultrasonic height was reporting that the drone was going closer & closer to ground.

At approx 145sec the forward obstacle sensors, the green graph, reported something closer than 2m in front of the drone. And at 163sec the drone stops & the heading speed goes to zero according to the dark green graph.

One reason for that the drone stopped can be that the front OD sensors sensed the ground ... this as it sees in a cone shaped area forward ... like below.

... or it could have been the bottom sensors that reached the auto landing height of 0,5m that made it stop ... but I doubt it as the log reports 0,61m as the closest distance to ground.

What happened me during that slow walk most probably hadn't saved my drone if the speed had been faster ... have seen numerous clips on YT where the drone crashes into the ground when it's following somebody that is mountain biking along a trail.

hiflyer201 · May 17, 2021

As others have said sometimes it's the terrain that is gently rising or falling. That can be hard to recognize if there is high terrain in the background. But for really low flight I would be wary. My P3S landed more than once uncommanded. I learned a lot about what not to do with that drone.

keat63 · May 17, 2021

I'd been reading a thread about the fear of flying over water.
There are a few small ponds near me where I've considered I might one day want to fly over.
My trial (low speed by the way) was to see how the mavic performed at a fixed low altitude.

Camino Ken · May 17, 2021

keat63 said:
I'd been reading a thread about the fear of flying over water.
There are a few small ponds near me where I've considered I might one day want to fly over.
My trial (low speed by the way) was to see how the mavic performed at a fixed low altitude.

Flying over water is virtually the same as flying over land except for the reduced chances of recovery in case of a mishap. I fly over a half acre pond all the time with the same flight behavior as over land.

keat63 · May 27, 2021

Just had a little play with active track.

After watching slups video I kept a real close eye on what the mavic was doing.
I was actually active tracking on quite a slope, the mavic adjusted it's altitude for the slope.
Did it do this because it's clever and knew where the ground was, or because it was tracking me who was also ascending.
I'd say it was flying at around 12 feet.
The slope is getting on 20 maybe 30 feet in altitude.

slup · May 27, 2021

keat63 said:
Just had a little play with active track.

After watching slups video I kept a real close eye on what the mavic was doing.
I was actually active tracking on quite a slope, the mavic adjusted it's altitude for the slope.
Did it do this because it's clever and knew where the ground was, or because it was tracking me who was also ascending.
I'd say it was flying at around 12 feet.
The slope is getting on 20 maybe 30 feet in altitude.

The behavior regarding how different Mavic models manage the height during Active Track have changed from one model to another ... My MA1 will not follow uphill in Active Track only downhill, can use Smart Capture (Hand palm maneuvering the craft) & then it will follow in both directions.

Don't know how a MP1 behaves ... it's possible that it tries to keep the framing & angle to the tracked object, leading to that it can manage both up & downhill if the speed isn't to high.

Post your mobile device .TXT log from a Active Track uphill flight & we can take a closer look.

keat63 · May 27, 2021

For the log file, I've a .info in the dji folder. Is this it.

slup · May 27, 2021

keat63 said:
For the log file, I've a .info in the dji folder. Is this it.

Nope ... go here & read up on how to retrieve the mobile device .TXT log (read under section 3.) --> Mavic Flight Log Retrieval and Analysis Guide Once retrieved just attach it to a new post in this thread.

keat63 · May 27, 2021

Let's see if this works. I only have 1 file for the day. The mp4 file is timestamp at 12:24. Lasts for 2.5 mins.

slup · May 27, 2021

Yeah ... a Mavic Pro 1 follows both up & down hill in Active Track. A valid question though, how fast can it fly before it can't keep up with the altitude change anymore?

Below in the chart you have the Active Track mode within the blue background color ... green graph is the VPS height, the red the barometric height & the blue the heading speed. Also added in all stick inputs just to confirm that no throttle command was added. The axis grid seen in the chart is according to the green graph ...

(Click on the chart to make it larger)