Low level

[Aussiemike]

Would someone please give me a rule of thumb guide to flying low over undulating ground. Will the sensors adjust height automatically when a small rise appears.
DJI Mini 2
Cheers Mike

 

[slup]

No, the Mini 2 doesn't have a terrain follow feature. Going really slow (snail pace), the Mini 2 might adjust the height up when ground rises slowly due to the VPS sensors ... but in general & as a thumb rule it will crash into the ground.

 

[Bodkin's Best Photography]

My driveway has a slight raise of 3 feet from the bottom to the top. Flying as low as possible the drone was able to compensate for the change in elevation and not crash. However doing this on uneven terrain at a slightly higher speed was not as successful and resulted in a minor crash.

 

[Alan Mac]

The altitude reading seems to come from the GPS rather than sensors. Flying from a slightly elevated position I quite often see negative numbers for altitude.

 

[Bodkin's Best Photography]

The altitude reading seems to come from the GPS rather than sensors. Flying from a slightly elevated position I quite often see negative numbers for altitude.

That is correct, but you'll notice the drone will slow down when it detects solid terrain beneath it regardless of where you launched off from.

 

[Alan Mac]

Yeah, true. Yesterday I did a few hand catches, and yeah noticed it jumps a little when I first put my hand under it.

I'm planning to eventually film from a (slowish) moving boat, so hand launch and retrieval are going to be pretty important I think.

 

[Bodkin's Best Photography]

Yeah, true. Yesterday I did a few hand catches, and yeah noticed it jumps a little when I first put my hand under it.

I'm planning to eventually film from a (slowish) moving boat, so hand launch and retrieval are going to be pretty important I think.

Absolutely. Landing on the deck can be difficult if you don't have a good amount of room as even a stationary boat will drift a little. Last time I launched from a smaller boat I got the pilot to beach it on a patch of clear shore we found. Hand catching was essential as there was minimal space on the deck.

 

[SkyeHigh]

The altitude reading seems to come from the GPS rather than sensors. Flying from a slightly elevated position I quite often see negative numbers for altitude.

Altitude (more correctly height above ground level), uses a barometric pressure sensor to reference the point from which you launch. If you then fly below that point, such as into a valley, you will get a negative reading.

The downward facing infrared sensors provide a more accurate height measurement below 30-metres to the ground.


GPS is used for horizontal positioning.

 

[Alan Mac]

Thanks for that!

 

[Aussiemike]

Thank you all.

 

[Zbip57]

Will the sensors adjust height automatically when a small rise appears.

It's always best to experiment, so you won't someday be surprised by its behaviour.

My Mini will only descend to a minimum height above ground of about half a metre. The infrared sensor detects the ground proximity and prevents it going any lower. Holding the throttle stick down at that point initiates auto-landing.

In slow flight, if the sensor detects anything closer than that, the Mini will automatically rise up to maintain that minimum ground clearance. You can see that if you hold your hand under it while it's hovering. The Mini will rise up. It can't react quickly enough when flying at speed though.

At the start of this video I was flying my Mini low over the snow, aiming to fly through the narrow gap under a fir tree branch. There's a tree stump hidden under that hump in the snow at 0:10 seconds. The infrared height sensor detected the Mini was too low passing over that stump and it automatically jumped up to avoid the stump, nearly tangling with the overhanging branch. Oops.

 

[RSDonovan]

Yeah, true. Yesterday I did a few hand catches, and yeah noticed it jumps a little when I first put my hand under it.

I'm planning to eventually film from a (slowish) moving boat, so hand launch and retrieval are going to be pretty important I think.

I'd love to fly from a boat, but I'd be very anxious!