"Precision Landing" 5ft off!

NullPointerException · Feb 28, 2019

I just got a landing pad for my Mavic Air, so I though I'd do a short test flight (with precision takeoff) and then do RTH to see how accurately it could land back on the pad.... it completely failed by my standards, as it missed the pad entirely by about 5 feet! Any ideas/suggestions/thoughts on why it failed so badly and how to improve it?

CanadaDrone · Feb 28, 2019

The home point must be recorded and you need to ascend vertically at least 7m / 23ft when you take off before moving in another direction in order for precision landing to work on the Air. What it does is image the ground during that time, which is how it knows to land precisely. There also needs to be something for the drone to use for reference, if you are landing on featureless grass or asphalt, it doesn't work well. Landing pads are great for that though. If you touch the controls during the precision landing, it will also cancel the precision landing and it will change where it lands accordingly.

NullPointerException · Feb 28, 2019

CanadaDrone said:
The home point must be recorded and you need to ascend vertically at least 7m / 23ft when you take off before moving in another direction in order for precision landing to work on the Air. What it does is image the ground during that time, which is how it know to land precisely. There also needs to be something for the drone to use for reference, if you are landing on featureless grass or asphalt, it doesn't work well. If you touch the controls it will also cancel the landing and it will change where it lands accordingly.

Like I said, I used the "precision takeoff" option which automatically ascends to 20ft. I was landing on grass, but on a big orange circular landing pad....

CanadaDrone · Feb 28, 2019

I don't know what to tell you then - did you touch the controls at all after initiating RTH? Was your home point updated? 7M is not 20ft but I doubt that makes much of a difference. Mine always worked. Try it several more times and see what happens. If it consistently misses then further investigation would be needed.

Prismatic · Feb 28, 2019

You also must initiate RTH more than 5m away from the Home point, or it will just land wherever it is. Also, RTFM.

NullPointerException · Feb 28, 2019

Prismatic said:
You also must initiate RTH more than 5m away from the Home point, or it will just land wherever it is.

I flew out to about 700ft before activating RTH.

Prismatic · Feb 28, 2019

I’ve learned that if I launch the MA in a brisk breeze, it appears to affect the accuracy of RTH, as if it’s drifted downwind a bit before getting a visual lock on the exact spot it’s supposed to return to.

Meta4 · Feb 28, 2019

NullPointerException said:
Any ideas/suggestions/thoughts on why it failed so badly and how to improve it?

Obviously yours wasn't using the Precision Landing feature or it wasn't able to get a lock on the grass.
Try a few more times and on different surfaces before writing it off on just once experience.

NullPointerException · Feb 28, 2019

Meta4 said:
Obviously yours wasn't using the Precision Landing feature or it wasn't able to get a lock on the grass.
Try a few more times and on different surfaces before writing it off on just once experience.

Not trying to be rude, but did you read my previous post? I'm landing on a big, bright orange circular landing pad...

Meta4 · Feb 28, 2019

NullPointerException said:
Not trying to be rude, but did you read my previous post? I'm landing on a big, bright orange circular landing pad...

I'm not being rude either.
Yes, I read the whole thread.
Did you read my post properly, because I've told you what should be obvious.

NullPointerException · Feb 28, 2019

Meta4 said:
I'm not being rude either.
Yes, I read the whole thread.
Did you read my post properly, because I've told you what should be obvious.

Yes I did; perhaps I don't understand how DJI's computer vision algorithm works.... I've done some CV myself, and if the system is just comparing images to try to line them up, one would think it would be to line up two bright orange spots very easily.

Meta4 · Feb 28, 2019

NullPointerException said:
Yes I did; perhaps I don't understand how DJI's computer vision algorithm works.... I've done some CV myself, and if the system is just comparing images to try to line them up, one would think it would be to line up two bright orange spots very easily.

There are two possibilities for your drone failing to land on target.
Either it wasn't using Precision Landing - perhaps it did not properly record images of the target etc.
or .. the PL feature was working but had difficulty.
Either way, you can't make determinations on the basis of one test failure.

SparkPlug · Feb 28, 2019

Also precision landing work best in full daylight.

NullPointerException · Feb 28, 2019

Meta4 said:
There are two possibilities for your drone failing to land on target.
Either it wasn't using Precision Landing - perhaps it did not properly record images of the target etc.
or .. the PL feature was working but had difficulty.
Either way, you can't make determinations on the basis of one test failure.

True, and I'll do some more testing as I have time. I guess I was just dissapointed that it failed so badly without giving any warnings like "unable to find target, preforming standard landing" or something like that.

StoneAIR · Feb 28, 2019

It’s a precision suggestion lol

AMann · Mar 1, 2019

NullPointerException said:
Like I said, I used the "precision takeoff" option which automatically ascends to 20ft. I was landing on grass, but on a big orange circular landing pad....

What is the “precision takeoff option which automatically ascends to 20ft.”?
Sorry, just have not seen that- I thought you were supposed to just go manually straight up to 7m and wait there a few seconds- works perfectly almost everytime for me, the only times it didnt were due to a breeze during takeoff. Maybe your GPS lock was weak with too high a PDOP or not enough satellites? Also, as mentioned before, wind pushing you just a few feet off the pad during the acquisition hover can mess it up.

Oh dang, my bad. MAir thread! I have a M2P, so it doesn’t sport the precision takeoff option- sorry about that, but the rest of my answer should be ok. Cheers!

StoneAIR · Mar 1, 2019

Just when you get used to something they change it.

patricwolfe · Mar 1, 2019

Try calibrating your IMU.

Luke147 · Mar 1, 2019

May I suggest that if you have lost contact with your drone and have no idea where it is and it goes into auto RTH mode and then lands within 5 feet of your take off point all by itself you will be very excited that it achieved the impossible! 5ft off spot would be just fine!

Jackcutrone · Mar 1, 2019

I pretty much always use precision landing since I got my orange 3’ landing pad and in over 50 flights it has never landed off the pad. Your idea to do more testing is good.