Landing Pads and Return to Home Accuracy

Starz · Feb 5, 2017

Took off straight up to 25 feet, sat for a few seconds, then up to 150 feet. Flew out to 1800 feet away. Hit rth, landed within 2 inches. The picture is the key. Used the floormat out of my truck as the landing pad.

SkeeterHarris · Feb 5, 2017

DownandLocked said:
I want to use a dock at a lake for take offs and returns. I've seen landing pads available with high contrast markings. Would this increase RTH accuracy. My dock is 8 feet wide and I don't want my Mavic landing in the water.

I've had two landings over the past few days with a high contrast landing pad by RcGeeks. The first time using RTH the Mavic came down was ready to land descended and missed the landing pad by a good 2 feet. Good news was when it came down it hovered and promoted me to complete.

Second flight same day another RTH from about 3k distance it came back, lowered down to landing. Confirmed position and dropped right on the landing pad. Perfect! I'll do more testing but if it were me I'd physically be there to "adjust" if needed.

Sent from my iPhone using MavicPilots

jamesgb · Feb 5, 2017

halley said:
No need to hover. Just take off straight and steady for 10 meters. It takes a series of photos to plot/recognize its return.

Ahhh, thanks for the clarification, makes sense.

Logger · Feb 5, 2017

Actually the 10m is just a guide. So is the straight and steady. Seems like some Landings pads may even foil a precision landing.

My take is that a near vertical climb is required, the min height is not, nor is a constant heading. I just ran a few tests always climbing vertically. First one was vertical 6m (20') and then flew off a distance before climbing to min RTH and hitting RTH. Precision LDG worked fine - so no need for a hard and fast 10m. Did this a few times and it is repeatable. Second test was take off and immediately hit full yaw and spiral madly up to just over 10m (33'), and again flew off a distance before climbing to min RTH and hitting RTH. Precision LDG again worked just fine. So no need for a constant heading at all. Again this is totally repeatable.

On the one occasion that it hung, up I took off from a sport field using a single 1 foot square & very bright green patch of grass as the take off spot. On return it Precision Landed (after a spiral climb) but hovered at 1' with "Ground unsuitable for LDG" warning instead of "Ground Plain safe to land". This is probably the same issue that foils some landing matts. I am not convinced high contrast is good as it can seemingly upset the Safe LDG site check.

I think you just need to be able to keep the LDG area in the cameras field of view above a landing area with a pattern it can resolve and record as it recedes.

jamesgb · Feb 5, 2017

Logger said:
Actually the 10m is just a guide. So is the straight and steady. Seems like some Landings pads may even foil a precision landing.

My take is that a near vertical climb is required, the min height is not, nor is a constant heading. I just ran a few tests always climbing vertically. First one was vertical 6m (20') and then flew off a distance before climbing to min RTH and hitting RTH. Precision LDG worked fine - so no need for a hard and fast 10m. Did this a few times and it is repeatable. Second test was take off and immediately hit full yaw and spiral madly up to just over 10m (33'), and again flew off a distance before climbing to min RTH and hitting RTH. Precision LDG again worked just fine. So no need for a constant heading at all. Again this is totally repeatable.

On the one occasion that it hung, up I took off from a sport field using a single 1 foot square & very bright green patch of grass as the take off spot. On return it Precision Landed (after a spiral climb) but hovered at 1' with "Ground unsuitable for LDG" warning instead of "Ground Plain safe to land". This is probably the same issue that foils some landing matts. I am not convinced high contrast is good as it can seemingly upset the Safe LDG site check.

I think you just need to be able to keep the LDG area in the cameras field of view above a landing area with a pattern it can resolve and record as it recedes.

If I'm at a sports field or tennis court and not using a landing pad, I always try and place the Mavic right on a line when I take off so it has something very specific to target when landing instead of a big open colored patch.

Logger · Feb 5, 2017

jamesgb said:
If I'm at a sports field or tennis court and not using a landing pad, I always try and place the Mavic right on a line when I take off so it has something very specific to target when landing instead of a big open colored patch.

Yes that would work.

Logger · Feb 5, 2017

Here is the spiral takeoff I described above.
Focus it a bit out, the messages are lagging a bit due to my screen capture tool. It is also a bit windy (gusting 20kph) , throwing the Mavic about. But it clearly works fine. I wont bother posting the 6m one, but suffice to say it worked fine too.

Here it one that aborted. I cut out everything up to the descent to save length.

Precision Landing accurately aligns aircraft, but LDG is stalled by sensors detecting green patch as uneven ground and unsafe to land.

Oyibo VFX · Feb 6, 2017

Mine landed on the spot... No problem

Adventure is just bad planning

deltalimatango · Feb 6, 2017

jamesgb said:
That's a good point. Maybe it could say something like, "visual acquired, precision landing will be attempted on RTH"

I just find myself hovering there wondering, did it get it yet??? [emoji1]

Sent from my Nexus 6P using MavicPilots mobile app

Just wrote to them with your suggestion.

deltalimatango · Feb 6, 2017

After reading a bit here, it seems that the best approach, and please correct me if I am wrong, is to simply rise vertically, then proceed in any direction you like. There is no need to actually hover in place. Does this make sense and am I understanding correctly?

Logger · Feb 6, 2017

Yes, that is a good assessment of how to do it. Up vertically to something approaching 10m before you head off laterally. That's it.

Mtb Uas · Feb 6, 2017

I've done a about 12 precision landings so far and all landed within 3in from the exact take off spot. I have a high contrast landing pad on a sheet of 4x4 siding.

Mtb Uas · Feb 6, 2017

I have done about 12 RTH's with precision landings and all the Mavic landings were within 3in of exact take off point. I painted a high contrast pattern on a 4x8 sheet of plywood. I just hit auto takeoff and lift vertically for about 50ft. Here is a pic of my takeoff/landing pad:
IMG_3048.JPG

Canucklehead · Feb 6, 2017

Okay dumb question alert.... Do I need to press the RTH button on the controller, or swipe the RTH on the tablet, to do a precision landing? Is it automatic regardless of the RTH mechanism?

My RTH height is 50m due to some tall high voltage towers in my area... if I can see the drone (say 10 m away and 10m up), will it always pop up to 50m first? I haven't done too much testing of the RTH since I always return it and land manually... and I can't seem to get a straight answer from the posts on here.

Logger · Feb 6, 2017

Either method triggers the same RTH process, which may include a precision landing.

If you cant get a straight answer from the posts here, try the user manual. Page 16 "RTH Safety Notices" explains it all.
No it wont climb to 50m.

Canucklehead · Feb 6, 2017

Logger said:
Either method triggers the same RTH process, which may include a precision landing.

If you cant get a straight answer from the posts here, try the user manual. Page 16 "RTH Safety Notices" explains it all.
No it wont climb to 50m.

Ha I didn't recall seeing that part in the manual - I will take another look! Thank you!

Blindluck · Feb 6, 2017

I believe the return to home function on the controller will climb or descend to a specific altitude you set then return to home, if you use the app and swipe it will return to home at the altitude you are currently at when you swipe the screen.

Wysiwyg · Feb 7, 2017

Personally, I would never rely on any form of self-landing if I'm that close to water or any hazards. I've had mixed experiences with and without landing pads. I always eyeball and land manually these days.

deltalimatango · Feb 7, 2017

Wysiwyg said:
Personally, I would never rely on any form of self-landing if I'm that close to water or any hazards. I've had mixed experiences with and without landing pads. I always eyeball and land manually these days.

Agreed. I just got a set of leg extensions that should make landing above ground a bit easier. With my P4, I always hand caught, but as the blades of the Mavic are a bit closer, I try to land as much as possible. I also have a high contrast landing pad. Gonna give it all a go this weekend if the weather is cooperative.

Logger · Feb 7, 2017

Blindluck said:
I believe the return to home function on the controller will climb or descend to a specific altitude you set then return to home, if you use the app and swipe it will return to home at the altitude you are currently at when you swipe the screen.

Your belief is demonstrably incorrect. So as people do not get confused, it is one and the same function, wiht two methods to trigger it. DJI refer to it as Smart RTH. In laymen terms, it is when you tell it to RTH, as against Low battery or Failsafe LOS RTH. I wont sprout the manual but it is described on p14 under Smart RTH in case anybody wants clarification.