Auto landed into a tree today

[GadgetGuy]

10 satellites is not enough for an accurate Home Point, but may be all you can get under the tree canopy. Lesson hopefully learned: don't use any automated landing features when flying above or among the tree canopies, as the automated landing features are intended for obstruction free flying environments. Land manually! It will save you a lot of grief!

 

[Meta4]

10 satellites is not enough for an accurate Home Point

Six sats is enough to give an accurate homepoint as long as they are well spread.
Ten is plenty.
The recorded flight data will show how good GPS was or wasn't and where a home point was recorded.

 

[GadgetGuy]

Six sats is enough to get a homepoint as long as they are well spread.
Ten is plenty.

I'll defer to your expertise. I usually have 12-14 after formatting the card in the drone, and getting the Green OK to Fly, but I am in a wide open area, and not under 100 foot tall trees!

 

[Perceivedshift]

Can't say I've activated RTH deep in some tall trees, your GPS position must have been off on take-off. I've only used RTH when things are very clear, I always use manual control when threading the needle into a forest. When I have used RTH it has been accurate to within inches!

 

[Maui19]

Epilogue: I've been through the flight log, and had enough other weird occurrences to finally get a handle on what happened.

My house sits among tall pines, but there are numerous areas that are open to the sky--for example my driveway, which is where I launch most flights from. Five seconds into this flight, with the MA2 hovering 4 ft off the ground and right in front of me, it established the home point. Unfortunately, it established the home point 30'-40' away, where there are some tall trees. I'm guessing this was a GPS error. Anyway, since I'm new to this, I didn't check the map to see where the home point really was. Later when I pressed the RTH button, it obediently moved to this mis-located home point.

From where I stood, it didn't look to be directly over the trees, and part of me was thinking that it would be heading back to where I thought the home point was. I triggered autoland, and that's when it descended into the tree. Fortunately, It just barely clipped some needles before I got it the heck out of there.

I understand the home point error. I still am not sure why the obstacle avoidance systems allowed it to descend into a tree. I need to look into this a little more.

Anyway, this whole episode turned out to be very helpful for several reasons. Perhaps most importantly, I am now VERY cognizant of the location of the home point. I had a flight the other day where the homepoint was established in the middle of a lagoon (yikes!). And I am also now less trusting of the automated features of the MA2. I mean the thing is a marvel, I just need to be sure it is doing what it is supposed to be doing.

Thanks for the input and interest!

 

[Meta4]

Five seconds into this flight, with the MA2 hovering 4 ft off the ground and right in front of me, it established the home point. Unfortunately, it established the home point 30'-40' away, where there are some tall trees. I'm guessing this was a GPS error.

I understand the home point error.

I don't.
Could you post the flight data so I can work out what actually happened?
Post #14 shows how to post data.

I had a flight the other day where the homepoint was established in the middle of a lagoon (yikes!). And I am also now less trusting of the automated features of the MA2.

Recording the homepoint shouldn't be problematic.
The data from that flight might also be helpful.

 

[Maui19]

The only thing that worries me (and is yet unexplained by anyone) is why the avoidance systems let it descend into a tree. Anyway I'm done with this thread (unless I autoland into a tree again!) Thanks everyone!

 

[Meta4]

The only thing that worries me (and is yet unexplained by anyone) is why the avoidance systems let it descend into a tree. Anyway I'm done with this thread (unless I autoland into a tree again!) Thanks everyone!

"GPS error" isn't a thing.

It would appear that you aren't really interested in finding out what actually happened.
Without that understanding, it could happen again.

 

[Maui19]

Of course GPS error is a thing. If you hike at all, you'd understand that lack of GPS signal, or intermittent signal can result in inaccuracy. I'm sure that's what happened here. Anyway, you seem to want to mix it up here, but I do not. Have a great day and a Happy New Year!

 

[Meta4]

Of course GPS error is a thing. If you hike at all, you'd understand that lack of GPS signal, or intermittent signal can result in inaccuracy.

I've been using GPS professionally for >20 years and analysing DJI flight data for 5 years.
I have a pretty good understanding of what GPS can and can't do.
Your drone won't record a homepoint until it has proper conditions for a good fix, rather than a dodgy fix acquired under poor GPS conditions.
That's probably what happened and your data would instantly confirm whether that was the case or not.

I'm sure that's what happened here.

You are sure but won't post the data so more experienced flyers can check to see what really happened and give suggestions to prevent similar problems in future.

Anyway, you seem to want to mix it up here, but I do not.

I want to mix it up??
I'm just baffled by someone that comes to the forum asking for help but backs off and refuses help when it's offered.

 

[DanMan32]

RTH landing strictly by GPS (no vision oriented precision landing) can be up to 5 feet off target, but not 30-40 ft!. That much deviation is usually caused by HP set during flight when proper GPS lock is aquired. Vision positioning system (VPS) would allow stability as high as 15 ft causing one to think they have GPS and HP set at takeoff.

 

[DanMan32]

Can't say I've activated RTH deep in some tall trees, your GPS position must have been off on take-off. I've only used RTH when things are very clear, I always use manual control when threading the needle into a forest. When I have used RTH it has been accurate to within inches!

It was within inches probably because of Precision Landing. That doesn't take effect until during landing, so just at the point of starting to land, it can be as much as 5 ft off target, and adjusts based on vision as it lands. If you don't have over 5ft clearance around the HP all the way up, it could still land into a tree.

If I have a tight spot to land, I only use RTH to get me back in the vicinity, then I manually land, using gimbal straight down to guide myself in.