Upward/downward sensing

[dxer]

Can someone explain how upward/downward sensing system is working on Mavic 2 Pro in outside environment.
I mean, when other sensors detect obstacle I see this on the screen left/right , forward/backward, but what about upward/downward obstacle alarm, where can I see this warning ?

I was testing this above my house roof, trees and nothing I can see is warning me about obstacle in this direction. Tried in tripod and P-mode.
I didn't try with above obstacle sensing but I figure this would be the same.

Or this direction sensors are activated only in indoor environment which is a shame.

 

[Not A Speck Of Cereal]

I'm not sure which bar of the obstacle detection status icon is for downward, but it's easily tested. The DJI GO 4 manual has this on page 1:

"Obstacle Detection Status: Red bars are displayed when an obstacle is close to the aircraft. Orange bars are shown when obstacles are in detection range."

Right after takeoff on flat land, move down until you get the warnings and see. If you test this and see no downward specific bars, please let us know. I think there's bars for front, bars for back, and a square in the middle (which I'm guessing is for up/down, shared).

Note: the M2P has both visual and infrared downward detection, but only infrared for upward.

Also, the Mavic manual states that the downward sensor is primarily designed for indoors, and is especially good for when GPS signal is lost, but I'm pretty sure it's working at all times that obstacle detection is turned on.

Chris

 

[Camino Ken]

The M2P has obstacle sensing in all directions but this is only available in Tripod mode. Position mode has all but the sides. Sport mode has none. This functionality is the same whether indoors or outdoors, the aircraft doesn’t know the difference. The graphical indicators on the app are very confusing. It is hard to depict 3D space on a 2D screen. I don’t usually look at where it is detecting the obstacle on the screen because it is obvious when you look at the drone and what it is near. Just listen for the beeps.

 

[dxer]

I was testing this today and was just about 2 meters above my roof and like 3-5 meters abouve tree and no beeps at all.
That is why I decided to ask for this as I don't see any warning about downward obstacle.

I will test some more in coming days and will get back to you guys if i figure this out.
But for now it is weird, because beeping and bars are fine all other sensors (sides/front/back). I just don't see warnings for downward, and like I said didn't test upward.

 

[Camino Ken]

Now that you mention it I am not positive that it beeps when near something from the bottom. I will have to check this next time I fly.

 

[dxer]

I was just researching this some more and it seems that downward sensors are actually not working as fron/backward and sides. While front/backward and sides are warning about obstacles, downward is not warning. It seems that downward sensors are only used for precision landing and for indoor positioning.
When you go to DJI Go 4 app and under Obstacle Avoidance Status, you can see icons for tripod and P-mode. For P-mode it is said that Only forward and backward vision system is available, so no down/up or sides. And I belive in tripod too down/up are not working.

Further more, in seetings where you can enable/disable downward vision positioning, like it is said, it is only positioning, it seems that it is not obstacle avoidance sensing. In this setting you can find Landing protection too where it is said that aircraft will check landing area .
I am not sure how this works because I was like 70-100 cm from landing on my roof or a tree and it was not warning me or protecting not to land on this surface.

Maybe someone else can give their input on this subject ?

 

[Camino Ken]

You could fairly easily test this yourself. Just let the drone hover in the air and use a piece of cardboard to test the different sides in the different modes.

 

[apeel]

The M2P has obstacle sensing in all directions but this is only available in Tripod mode. Position mode has all but the sides. Sport mode has none. This functionality is the same whether indoors or outdoors, the aircraft doesn’t know the difference. The graphical indicators on the app are very confusing. It is hard to depict 3D space on a 2D screen. I don’t usually look at where it is detecting the obstacle on the screen because it is obvious when you look at the drone and what it is near. Just listen for the beeps.

I agree that the graphical representation on the DJI Go 4 app for obstacle detection is very confusing. Whenever I get a beeping sound, I spend way too much time trying to figure out the indicators. Is there anyone who can point to a video or create some screenshots of what the obstacle avoidance visual indicators look like from Front, Back, Left, Right, Top, and Bottom obstacles? This would be very helpful and much appreciated!

 

[PimV]

Here a screenshot of the SC (camera view) with the M2P sitting on the dining tabel with a big lamp hanging above it. The colored arcs at top and bottom (0.5 M) are the obstacle warnings. Because it is in P-mode the side sensors are off (see the icon just right of the GPS-icon in the top-right row of icons). If you switch to T-mode also the side sensors are switched on. If you switch to S-mode al sensors are switched off. In P-mode after I do an automatic take-off (and nothing else) it hovers about 5 ft above the ground and beeps all the time because of bottom obstacle warning until I move it higher up.

 

[apeel]

I thought that the arcs on the top of the screen is the forward looking sensor and the arc on the bottom of the screen are the rear facing sensor. Is that not correct? What / where are the indicators for the bottom (the table) and the top (the lamp) sensors?

 

[dxer]

I it is beeping because of downward sensor when taking-off, then why is it not beeping when you are near obstacle ?
@PimV I don't think that this beeping got to do with downward sensing, more likely with some other sensor forward/backward

 

[PimV]

@apeel - That thought never occurred to me. The manual says: "Obstacle Detection Status: orange = in detection range; red = close to aircraft." But not in which direction. I assumed upward and downward because of their position in de camera view, but I may well be wrong.
@dxer: You might be right, but it is definitely beeping when it nears an obstacle.
On the table, in T-mode, when I put my hand in front of the side-sensors I don't get a reaction.
In P-mode, with landing protection on, when I bring it down and try to grab it in the air, sometimes I can grab it straight away, but sometimes it goes up again to avoid my hand.
My conclusion: at lot is unclear about the functioning of the obstacle avoidance systems.
But I am sure they work outdoors as well.

 

[dxer]

I will test some more but like I said, when I go above my roof or nearby trees , I am directly descending over them and no beeps or any other warning and I am like 70-100 cm over.

 

[PimV]

Okay, I have done some experimenting: I let the AC hover in the middle of a football field at 5 feet height and walked around it. I fly it with the Smart Controller. On the screen of the SM the top arc indicates forward obstacles, the bottom arc backward ones. There is no reaction from the upward, downward and side sensors (not in P-mode and not in T-mode). If I try to grab the AC from below it evades my hand (goes up), so the downward sensor does work. Normally, if I try a few times I can grab it, but this morning it went up every time I tried. Finally I switched "Safe Landing" off and could grab it straight away. I assume that the different reactions to my hand under the AC are caused by differences in lighting (a hand is not that big).

 

[cpfninja11]

The sensors on this drone are not all the same. The front and back sensor can see in 3D by detecting depth with 2 cameras like our eyes do. These sensors are represented by the small arc on top and the larger arc on the bottom. The side sensors are powered by only one camera on each side. These cameras cannot sense depth but can calculate distance based on changes in perspective when the drone moves. The single camera sensors are not as reliable. The top and bottom sensors are also similar but not exactly the same. The top sensor (Time of Flight Sensor) shoots a beam of infrared light and measures the time it takes the light to reflect off an object and return to the sensor. This sensor can only detect objects that are directly above the sensor. The bottom sensor array is composed of the same Time of Flight sensor and two extra cameras. During flight the drone uses the bottom facing infrared sensor to maintain an accurate distance from the ground and the cameras to achieve more precise hovering horizontally. You will not get any obstacle avoidance warnings from the bottom sensor except during landing. When the landing slider is activated the drone will use the two cameras on the bottom to check for unsafe terrain and will not land automatically if the ground is too dangerous. If the ground is safe the drone will land.

 

[Deleted member 103366]

Indoors and outdoors if the M2P I was flying detected an object over head I saw a 'written' warning on the screen, something like "obstacle overhead". Ceiling indoors, branches outdoors. Once the warning had appeared the drone 'fought' climbing. Outdoors I was able to climb once I had flown the drone out from underneath the branches.
That I remember there was no diagram/map/chart, I don't remember if the warning was persistant nor if there was a warning vibration. I am deaf so can not say if there was a beep.
If, above a clear floor, you hover the drone slightly below shoulder height and put your hand above the top sensor (be careful of the props) the drone will descend. You can 'push' the drone downwards by moving your hand towards the drone, if you try this DO IT SLOWLY, my first attempt was not slow and the drone descended rather quickly, too quickly for my comfort.
Ultimately I think it becomes a contest between the downward and upward looking sensors as to what the drone does. I stopped 'pushing' the drone down when it was about 6" off the ground. The drone might have climbed back to a 'minimum height' when I took my hand away but I can not be certain.
With regards to the downwards looking sensors, I never saw a warning but it might be worth checking if the VPS height indicator becomes active when you are low over an object