RTH Dumb question No1

If I fly my Mini2 drone from the top of a hill and the RTH is set to say 30/40 mtrs, I then fly the drone down the hill but the hill is deeper, what would happen if I pressed the RTH, would it crash into the side of the hill.
Because the Mini 2 hasn’t avoidance sensors I’m guessing that it gets its measurement from the satellites BUT as with car GPS systems this can give false readings due to the terrain ie when going down a hill at a certain speed.

I hope this question makes sense?

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Sort of

The M2 gets its height from take off position, so if you do fly below the take off height it will read a minus altittude.

The RTH height is xxM above take off point, so you wont hit the hillside

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Thank you Chris, makes perfect sense but in my defence, I did say it was a dumb question :crazy_face:

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Not dumb at all. If you are ever unsure about anything it is a lot easier to ask a question In here and then flly safely than not ask and crash.

Drones are getting smarter but RTH can still catch people out,

For instance:

Scenario 1. You set the RTH height to 30 metres. Then you fly at a height of 20 metres on a dog-leg course to avoid a clump of tall trees (45 metres) Your aircraft disappears behind the trees and you have lost orientation so press the RTH button. What happens?

Scenario 2. You are making video of a large bridge. Before you set off you set the RTH height to 30 metres. You decide to fly directly toward the bridge and pass under the deck which is 20 metres from the surface of the water. While under the mass of steel your aircraft loses signal. What happens?

:question: :question: :question: :question: :question: :nerd_face:

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macspite…Answer…Panic! :open_mouth:

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Different answers depending where you were in relation to the obstacles when you launched. For example 2, you could be on the bridge, fly away from it then fly directly towards it.

One thing to note with RTH, it behaves differently if you are 20mtr or less from the home point. If you have it set to return and land, it will land where it is.

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Indeed - further complication!

To clarify. You are 100 meters from each obstacle.

Hi Macspite,
Good questions there. I’m not a Mini2 owner but as it has no avoidance sensors then my guess would be:

  1. As RTH height is set at 30 metres and those trees are 45 metres and directly in the path of RTH - it will hit a tree and crash.
  2. Hitting RTH under the bridge (if you have lost signal - in theory the drone would not have received the RTH command - so I guess it would attempt to RTH anyway in a loss of signal scenario - so it would rise to 30 metres and hit the underside of the bridge deck and end up in the water.

So that’s my final answer …|

Richard

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Ultimate answer is it will crash

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Yes, like many things RTH is a great feature if used with a bit of thought as to how it works …

2 has other answers but they’re all fatal. Land, splash. Hover, until battery level drops and it’ll either RTH or land.

macspite, sorry for the flippant answer.
Scenario 1. I would or should have taken into account the height of the trees in my flight path and set the RTH accordingly.

The bridge is a different ‘kettle of fish’ and to be honest I doubt that would ever arise for the obvious reason…I wouldn’t know what to do.

Forward planning is crucial BUT hindsight is a wonderful gift :wink:

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Just to help / confuse matters - RTH and Active Track:

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I’m easily confused I’ll admit :crazy_face:
So I’m clear that on a DJI Mini 2,
When the drone takes off it sets a home point at the take off location and if you leave that as the setting and all else is good with the altitude etc, any RTH function such as low battery, failsafe or manually requesting it from the app or button on the controller will make the drone return to the take off point.
Unless the home point is less than 20 metres from the drone at the time.
In this case does it do nothing but hover or land where it is?

But more questions,
If I update the home point during flight (lets assume all the altitude settings are suitable) then activate RTH it will by default return to where the drone was when I reset it, as opposed to returning to where the controller was at that time?
I assume the 20 metre thing will be the same answers as to the question above?
Can I change the RTH home point (defaulted to where the drone is) to where the controller is ?
Or is the only option to drag the map so the new home point icon and controller icon location are aligned?

I’d like to see RTH options on the screen split into 3 and read

  1. Return to take off point location
  2. Return to controller location
  3. Custom home point location (Drag map)
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RTH less than 20mtr away, try it & let us know, I think it obeys whatever you’ve told it to do e.g. land or hover.

If RTH is changed, it obeys the settings relevant to the new RTH.

You can change RTH to wherever you want.

You can already set RTH as your 1 2 3 options.

One thing to be very aware of. If the app crashes, when you re-launch the app it sets the RTH wherever the drone is when the app connects to the drone. Happened to me this afternoon and Airdata log shows RTH set at 163ft as the app launched.

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I was hoping someone who owns a Mini 2 might answer as I don’t have one. My experience of RTH is on Wookong, NAZA and A", Inspire and Mavic Air.

So I had a brainwave - I looked in the Mini 2 manual !

DJI_Mini_2_User_Manual_EN.pdf (13.7 MB)

I learnt this:

As the home point is only recorded when sufficient satellites have been recorded it;s a good idea to hover after takeoff until the aircraft status indicator blinks green.

So RTH behaviour less than 20 metres away seems dependent on firmware level.

If you set a new home point during flight them that is where the aircraft will go in case of signal loss or pressing the RTH button:

This is an overly long and badly made video I skipped through where the guy claims to be able to set a home point that is neither take off nor current position - ideal if you know where you are going and want your aircraft waiting for you when you get there …

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I have a Mini 2 but I try not to rely on RTH, always a last resort rather than the lazy way home. The manual is out of date the minute it’s published.

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@macspite

You have made me feel naive and a very lazy.
Thank you ever so much for your effort. Thats brilliant and you have confirmed what I was thinking from bits and pieces I half remembered before purchase (that didn’t sink in).
In my feeble defence, I did manage to find a DJI Mini manual but not mini 2 (just popped up in my search before I posted my questions) and saw some video’s that missed the point I was after.
I am a dinosaur :man_shrugging:

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DJI manuals are ok if you have full knowledge of the kit they describe anyway. Not brilliant for first time users :frowning:

O have only had one RTH incident and glad to say it worked very well. Like you I prefer to land the aircraft manually.

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It’s helped me sharpen up my knowledge of the subject especially as my youngest aircraft is an original Mavic Air. :lizard: :lizard: :dinosaur :dinosaur :slight_smile: