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RTH and obstacle avoidance
3444 16 2017-6-7
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hallmark007
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RTH and obstacle avoidance is a lot different than Mavic with one new cool feature, if your spark is returning home for i.e. Signal loss, and it meets an obstacle it will not just climb to to clear obstacle like Mavic does (sometimes causing it to crash into over hanging balconies or trees)  it will back up first (this is new) before it then rises to clear obstacle before returning home. Good job dji...
2017-6-7
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Nigel_
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Excellent, there have been a few crashes on P4 that this could have avoided.

Not sure I would want to program it though, so many things that could go wrong when you can't see the full shape of the tree that you have flown under!
2017-6-7
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Lucas775
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That it awesome to know that DJI did that.  
2017-6-7
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TheFlyingDutchm
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If I read the manual correct it says that obstacle avoidance on rth only works up to max 100m distance. Am I reading correct, and if so... Whyyyy?
2017-6-8
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MAVICDLNM
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Nigel_ Posted at 2017-6-7 12:46
Excellent, there have been a few crashes on P4 that this could have avoided.

Not sure I would want to program it though, so many things that could go wrong when you can't see the full shape of the tree that you have flown under!

is there an obstacle avoidance setting let you choose go up or sideway when there is object in front while RTH?
2017-6-8
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Nigel_
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MAVICDLNM Posted at 2017-6-8 23:54
is there an obstacle avoidance setting let you choose go up or sideway when there is object in front while RTH?

Only choice is "stop" or "stop and climb over".  No sideways option.
2017-6-9
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Nigel_
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TheFlyingDutchm Posted at 2017-6-8 21:40
If I read the manual correct it says that obstacle avoidance on rth only works up to max 100m distance. Am I reading correct, and if so... Whyyyy?

That means that it can see obstacles at up to 100m in front of the aircraft, the further forward it can see the faster it can fly with obstacle avoidance working.
2017-6-9
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hallmark007
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TheFlyingDutchm Posted at 2017-6-8 21:40
If I read the manual correct it says that obstacle avoidance on rth only works up to max 100m distance. Am I reading correct, and if so... Whyyyy?

No it will RTH at max distance, it cannot detect obstacles over 100meters , when it detects obstacles at 5 meters it will slow down stop fly backwards then climb to clear obstacle and then continue home.
2017-6-9
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TheFlyingDutchm
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The attached picture is from the manual. It looks to me that RTH does not support Obstacle Avoidance beyond 100m?
IMG_0923.PNG
2017-6-9
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hallmark007
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TheFlyingDutchm Posted at 2017-6-9 16:14
The attached picture is from the manual. It looks to me that RTH does not support Obstacle Avoidance beyond 100m?

That is what I was trying to say sorry about bad English .
2017-6-9
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TheFlyingDutchm
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So if  I am 200 meters away from the Home point and RTH kicks in, there is no Obstacle Avoidance available.....
2017-6-9
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hallmark007
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TheFlyingDutchm Posted at 2017-6-9 16:38
So if  I am 200 meters away from the Home point and RTH kicks in, there is no Obstacle Avoidance available.....

I think it might be a mistake in the manual will have to check with dji, but I don't think this can be right.
2017-6-9
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hallmark007
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TheFlyingDutchm Posted at 2017-6-9 16:38
So if  I am 200 meters away from the Home point and RTH kicks in, there is no Obstacle Avoidance available.....

Hi flyingdutch I have read through manual again and it seems there is no OA if you hit the RTH outside 100 meters, it's not clear from the manual if when you get inside 100meters that OA will now be working.

There are no explanations as to why this would be it seems a bit strange whether it's to do with speed which for RTH is 10 m/s 36kph , but if this was the case then OA would not work throughout RTH because you would be travelling at the same speed all the way home.

So maybe a moderator could jump in here and explain how or why OA doesn't work outside 100 meters.

Very confusing!!!!!!!!
2017-6-10
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ACW
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hallmark007 Posted at 2017-6-10 03:33
Hi flyingdutch I have read through manual again and it seems there is no OA if you hit the RTH outside 100 meters, it's not clear from the manual if when you get inside 100meters that OA will now be working.

There are no explanations as to why this would be it seems a bit strange whether it's to do with speed which for RTH is 10 m/s 36kph , but if this was the case then OA would not work throughout RTH because you would be travelling at the same speed all the way home.

The reason being is that the front OA on the Spark is only effective at speeds of 6-7MPH as it only has a 5m visual range (infrared sensor, similar to the side sensors on the P4P). If the drone is >100M away and RTH activates, it will cruise back at the standard P-mode max speed of 12-13MPH and thus disengage OA in order to achieve that speed and increase the likelihood of the drone actually returning safely.
2017-6-10
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hallmark007
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ACW Posted at 2017-6-10 04:19
The reason being is that the front OA on the Spark is only effective at speeds of 6-7MPH as it only has a 5m visual range (infrared sensor, similar to the side sensors on the P4P). If the drone is >100M away and RTH activates, it will cruise back at the standard P-mode max speed of 12-13MPH and thus disengage OA in order to achieve that speed and increase the likelihood of the drone actually returning safely.

According to the manual OA in RTH aircraft will return at speed of 10 m/s 36 kph not 14 mph , as you say and I understand going at that speed that OA will be disabled .
But the manual goes on to say what happens with OA when returning home i.e. If it meets obstacle it will fly backwards ascend for 5 seconds and the continue and this is my point about confusion,
2017-6-10
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milksteak
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TheFlyingDutchm Posted at 2017-6-9 16:38
So if  I am 200 meters away from the Home point and RTH kicks in, there is no Obstacle Avoidance available.....

I took a screenshot from within the app that mentions no obstacle avoidance over 80m.

RTH Object avoidance description

RTH Object avoidance description


Obstacle avoidance has a very limited range of like 4-5meters, so it can't fly faster than 2.5meters/s and still have enough space to brake.  I think the RTH return speed is preset to fly in excess of this speed limit in order make it home within reasonable time.  Why?  I don't know.  I wish we could have the option to change this.

Allow us to select RTH from options like this:

Automated RTH behavior (low battery RTH, loss of signal, etc.)
A. Stay within obstacle avoidance speed limits (2.5meters/s) at ALL TIMES and land wherever it is if it runs out of battery before returning home.
B. As A, unless RTH approximation against battery life does not allow successful return, then auto switches to mode C until it CAN make it, then auto slows to within obstacle avoidance speed limits.
C. Mixed speed mode.  I think this is the current functionality - it flies quickly outside of a certain distance to cover ground without obstacle avoidance, and switches to low speed mode within a certain range. I'm not sure what the purpose do this mode is for, balance of battery life and safety I guess, but I think we can just keep A and B, whic this mixed mode can be full sport mode speed.
D. Hover until out of battery and then land

Manual RTH activation (sudden inability to continue flying, emergency quit, alt+f4)
A. B. and C. as above.  These options can be asked each time I slide my thumb across to call for RTH manually.

THEN, the battery graph with the live-adjusting RTH warnings can have two color-coded RTH flags.  Green for RTH mode-A and Yellow for mode-B and then Red for mode-C which constantly adjusts itself on the battery graph as I fly, showing me what safety nets I have left in my flight.  You can also set <80m it defaults to mode-A or how it currently functions.  The above options are for >80m RTH behaviors using the remote.

Basically - what I want to know is if i'm flying in sport mode and I took about 90seconds at a rate of 14meters/s to fly out to 1300m with the remote in sport mode, that for whatever reason it needs to go into RTH; that I can do so within the obstacle avoidance speed limit of 2.5meters/s in under 9 minutes and I want it marked on the battery graph, as silly as it would look seeing a RTH warning at 65-70% battery life.  If I wanted to be safe, at that point I could react by bringing it closer to home by around 85%, which should show an adjustment to the on-the-fly RTH warnings and give me additional buffer time. Or I don't have to act upon it at all, but having the info there so that I can make a choice, gives me a sense of security.   DJI has the on-the-fly low battery RTH automation already, but the problem is with the lack of obstacle avoidance when it's further out.  I echo the reactions that others have.  Why?  You engineered it, but then you took it away... can't it just fly back slower?  Give us the option please.

All that being said, this whole topic is a non-issue for anyone flying using the phone, as the max range is only 80meters give or take a few. I experienced the connection cut out at around 76m in an open-area park.  So obstacle avoidance can and will be on at all times based on how RTH is currently working.  

2017-6-10
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hallmark007
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milksteak Posted at 2017-6-10 23:16
I took a screenshot from within the app that mentions no obstacle avoidance over 80m.


Well I suppose if your more than 80meters out you need to have proper height value set , manual does say it will return at 10 m/s or 36 kph.

But maybe dji should have another look at this we shall see.
2017-6-11
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