Return to Home setting confusion

[reemas]

Which setting is applied when both are in effect? See image. If my M2P is at 40m, will it descend to 30m as set? If it's at 10m, will it rise to 30m? Or will it return at its current altitude regardless of the 30m setting?


View media item 2240

 

[Meta4]

Which setting is applied when both are in effect? See image. If my M2P is at 40m, will it descend to 30m as set? If it's at 10m, will it rise to 30m? Or will it return at its current altitude regardless of the 30m setting?

Your image doesn't show but the simple principle is that your drone will climb to the set RTH height if it is below that.
If it is already higher, it will just come home.

 

[Valden]

Thanks for raising this Reemas. I'm also trying to figure out the relationship between the following, under Main Controller Settings:

- RTH at current altitude, and
- Return-to-home Altitude

Version 2018.08 of the manual advises (on page 18 under the heading RTH Procedure) that if the aircraft is more than 20m from the home point it will return to home at the higher of the Return-to-home altitude or the current altitude. Good. There's no mention of the 'RTH at current altitude' selection.

This makes me wonder what the 'RTH at current altitude' selection does. A possibility is that if it's selected to on, it will cause the aircraft to override the 'Return-to-home Altitude' and come back at the current altitude, even if lower. I'm assuming that the Vision Systems will still operate, hopefully lifting the aircraft over obstacles.

Thoughts?

 

[Meta4]

This makes me wonder what the 'RTH at current altitude' selection does. A possibility is that if it's selected to on, it will cause the aircraft to override the 'Return-to-home Altitude' and come back at the current altitude, even if lower.

There's not much to wonder about.
The name makes it very clear.
You might use that setting if you had the RTH height set rather high and knew there were no obstacles in the RTH path.
It would avoid an unnecessary climb to height and another slow descent from up high.

 

[Valden]

There's not much to wonder about.
The name makes it very clear.
You might use that setting if you had the RTH height set rather high and knew there were no obstacles in the RTH path.
It would avoid an unnecessary climb to height and another slow descent from up high.

Thanks Meta. It looks like we agree - on what the 'RTH at current altitude' setting might do. If we don't get confirmation from testing, I'll do some.

 

[Valden]

So I did some testing of the 'RTH at current altitude' setting today. The results are not what I was expecting.

With a number of flights I positioned the Mavic 2 Pro on the other side of a 3m high hedge, at a distance of 60m from the home point. With the M2P hovering at 2m above ground I activated Return to Home. With each iteration the aircraft climbed to the exact RTH altitude, which was set at 20m. It did not attempt to fly towards the hedge at current altitude and then climb a little to get over it.

I then tried with the M2P starting at 10m altitude, clearly higher than the hedge, with a clear path back to the home point. The obstacle sensors were not picking up any obtrusions. Again, the aircraft climbed to 20m and returned to home. It did this every time, regardless of the current altitude. It was not possible to induce a return to home at less than the Return to Home altitude. This is fine by me, but I want to be sure about what the effect of the 'RTH at current altitude' setting is.

The User Manual states (on page 18), 'If the current altitude is higher than the RTH altitude, the aircraft flies to the Home Point at the current altitude.' Yep - easy to understand. What is not made clear is whether the 'RTH at current altitude' setting needs to be 'On' for this to happen, or whether this desirable behaviour happens by default. If it does, then what's the setting for?

I will run more tests tomorrow. The M2P will be hovering at well above the RTH altitude. I will test what it does with the 'RTH at current altitude' setting both on and off. Any other suggestions?

 

[Simmo]

 

[Valden]

View attachment 45346

G'day Simmo. Thanks for this. My manual for the Mavic 2 Pro has a similar page. Does your Mavic have a 'RTH at current altitude' setting? What was its effect, exactly?

To be clear, with the Mavic 2 Pro and DJI Go 4 there are settings for both 'RTH at current altitude' and 'Return-to-Home Altitude'. I want to clearly understand the inter-relationship between these two settings. I'll ask you to excuse me for not knowing what settings were available in the Mavic 'Classic' models.

 

[reemas]

What is not made clear is whether the 'RTH at current altitude' setting needs to be 'On' for this to happen, or whether this desirable behaviour happens by default. If it does, then what's the setting for?

I will run more tests tomorrow. The M2P will be hovering at well above the RTH altitude. I will test what it does with the 'RTH at current altitude' setting both on and off. Any other suggestions?

Thanks for doing this. This is exactly what I was wondering. There seems to be some overlap here. Curious what your next set of tests reveals. I guess as you’ll be above RTH altitude for these tests, ideally with the setting off it’ll lower itself and RTH. And with the setting on it’ll just RTH. But who knows and honestly that’s kind of a strange feature to have anyway.

 

[Valden]

So I did some testing of the 'RTH at current altitude' setting today. The results are not what I was expecting.

<snip>

I will run more tests tomorrow. The M2P will be hovering at well above the RTH altitude. I will test what it does with the 'RTH at current altitude' setting both on and off. Any other suggestions?

Well I did those tests today and I'm still confused, as to what the 'RTH at current altitude' setting is meant to do. As far as I can tell, it has no effect.

I had the Mavic 2 Pro hovering at 40m with the Return to Home altitude set at 20m. For several tests, the aircraft flew back to the Home Point at 40m, when 'RTH at current altitude' was both on and off. This suggests that the M2P's default behaviour is to fly home at the higher of either the Return to Home altitude or the current altitude, which is consistent with the User Manual 2018.08 on page 18. Good. So far I have been unsuccessful in using the 'RTH at current altitude' setting to stimulate any behaviour that is different from the default.

One more test I will try is to position the aircraft in free space at say 20m, with no detectable obstacles in the sensors' field of view or range, but with a large, dense tree between it and the home point. The Return to Home altitude will be 40m. I'm hypothesising that if the aircraft starts in clear air and with 'RTH at current altitude' on, perhaps it will begin the RTH process at the current altitude, only rising when it sees the tree. Hmmmm. I think I'll choose a soft looking tree.

 

[reemas]

Well I did those tests today and I'm still confused, as to what the 'RTH at current altitude' setting is meant to do. As far as I can tell, it has no effect.

I had the Mavic 2 Pro hovering at 40m with the Return to Home altitude set at 20m. For several tests, the aircraft flew back to the Home Point at 40m, when 'RTH at current altitude' was both on and off. This suggests that the M2P's default behaviour is to fly home at the higher of either the Return to Home altitude or the current altitude, which is consistent with the User Manual 2018.08 on page 18. Good. So far I have been unsuccessful in using the 'RTH at current altitude' setting to stimulate any behaviour that is different from the default.

One more test I will try is to position the aircraft in free space at say 20m, with no detectable obstacles in the sensors' field of view or range, but with a large, dense tree between it and the home point. The Return to Home altitude will be 40m. I'm hypothesising that if the aircraft starts in clear air and with 'RTH at current altitude' on, perhaps it will begin the RTH process at the current altitude, only rising when it sees the tree. Hmmmm. I think I'll choose a soft looking tree.

Thanks again and let us know about the follow up test. Curious of that works. The option overall seems silly. Let's hope they turn it into the precision landing switch instead!

 

[Tridiver]

You shouldn't be using RTH so much anyhow. You should know how to fly with your own knowledge of how much bat you have left. If you loose signal, like I do during distance tests, just wait till it flies back into range and cancel RTH and take over flight. Just don't turn on RTH at current altitude and be done with it. Set regular RTH altitude correctly and forget about it.

 

[reemas]

You shouldn't be using RTH so much anyhow. You should know how to fly with your own knowledge of how much bat you have left. If you loose signal, like I do during distance tests, just wait till it flies back into range and cancel RTH and take over flight. Just don't turn on RTH at current altitude and be done with it. Set regular RTH altitude correctly and forget about it.

Definitely agree with this. Also not the point of this discussion.

 

[Broken Arrow]

I have the "Original Mavic Pro", if it is close to the Home Point ( I forget the distance ), it will return and land even if the current altitude is lower than the RTH height. I guess the reasoning is you have line of sight with it being close and can manually land if need be.
I'm guessing here, maybe the MP2 nows gives you the option of rising to the RTH Altitude even if near the Home Point. Seems much safer in case the Home Point is near a taller object and has the likelihood of a collision. Add that test next time you fly to see if I could be correct. Welcome to the community!

 

[bushie]

You shouldn't be using RTH so much anyhow. You should know how to fly with your own knowledge of how much bat you have left. If you loose signal, like I do during distance tests, just wait till it flies back into range and cancel RTH and take over flight. Just don't turn on RTH at current altitude and be done with it. Set regular RTH altitude correctly and forget about it.

I use RTH on almost every flight same as I use cruise control most of the time I am driving. That's what its for. Same as I am using a computer at the moment and not pen and paper.

 

[KennyJr]

I like to manually take off and land myself, but I still plan on testing RTH the next time I fly just to know it's advantages and limitations.

As an example my P3P returns to within 10 or so feet from take off point which is fine most of the time but at home that 10 or so feet could put it into the trees or hedges. When I was testing the Mavic using a plain white 2' by 4' table as a landing pad the Mavic stopped just inches above the table because the all white table had no marking for the Mavic to lock on to. The wife won't let me deface her picnic table so I either have to make or buy a landing pad.

 

[HoozierDroneDaddy]

Here is a breakdown of RTH directly from DJI.

How to use DJI’s Return to Home (RTH) Safely - DJI Guides

 

[Valden]

I've been discussing the 'RTH at current altitude' setting with folk at DJI support. As I feared, this has resulted in increased confusion, but I'm sticking at it in the hope that they'll realise there's a problem. More than one actually.

I sent them a screen shot of the warning message that comes up when seeking to activate the 'RTH at current altitude' setting. Firstly, the sentence structure is ar$e about, causing confusion. Secondly, I actually think this warning message is meant for a different setting altogether! Here it is.

Warning. When enabled, the aircraft will land in place when RTH is triggered within 5 m of the Home Point. When disabled, the aircraft will land in place when RTH is triggered within 20 m of the Home Point.

This message is not about RTH altitude! It's about landing precision. Either way, it would be clearer if it was written like this:

Warning. If enabled, when RTH is triggered the aircraft will land within 5m of the Home point. If disabled, when RTH is triggered the aircraft will land within 20m of the Home Point.

I'll post again when there's news.

And of course, I agree with the sentiment in several posts above - we should all be skilled at landing our Mavic 2s manually. This issue is not about that.

 

[Valden]

OK, it's all becoming clearer. With replies from DJI Support and some more of my own testing I'm feeling less confused about what the 'RTH at current altitude' setting for the M2P is all about. It's not good though.

Firstly, it should have a different label. Instead of 'RTH at current altitude' it should be titled, 'Do not land in place. RTH before landing.' I put it this way because, if the setting is 'On' and RTH is activated while the aircraft is within 20m of the Home Point, it stops the M2P from landing right where it is and makes it actually return to the Home Point first. This return flight will be at 2m, or at the current altitude if higher than 2m. If the setting is 'Off' when RTH is pressed and the aircraft is within 20m of home, it will not return home. It will simply land. Yikes!

Hands up, if like me, you find that the default behaviour of the M2P is to land somewhere other than the Home Point in some circumstances when Return to Home is initiated, to be both unexpected and undesirable? The fact that this problem only arises if RTH is initiated while the aircraft is within 20m of the Home Point is no mitigation. Imagine that you're getting to know your M2P in your backyard and it flies away a short distance and is now hovering over the neighbour's pool. It's only gone 15m but you just want it to come home. You press RTH and then, instead of returning to home as you might reasonably expect, it immediately descends into the water and goes blub, blub, blub. WTF!

I'll have another try at explaining these problems to the good folk at DJI. I would be proud if I could write in Chinese or any second language as well they can write in English. Notwithstanding, my experience so far is that their English is not quite good enough to handle the subtlety of the discussion that needs to be had.