My MA2 seems to have a home point error that accumulates after each flight.  While the "D" distance from RTH point grows after each launch, the RTH will many times be exactly as the take off point, but some times can vary many meters.  I can sometimes land "hands off" with the MA2 touching down at the exact same point as take off.  But sometimes it will try to land on the roof of my house, or worse, in the neaby pool!

Is this a common error where the exact RTH point will drift?

Thanks in advance and to those offended by my use of Imperial units, I think metric in my head  ;-)

Craig

Hi Craig,

Not had your experiece yet....   ;-)  But the only way to get a HP not exactly at the takeoff point is when your start to fly away from your start point without enhough satellites amd/or reception.
HP is set when the reception is at 4 ; range = 0 to 5.

"D" distance seen in the app is the direct distance drone<>HP.
cheers
JJB

JJB* Posted at 12-27 08:32
Hi Craig,

Not had your experiece yet....   ;-)  But the only way to get a HP not exactly at the takeoff point is when your start to fly away from your start point without enhough satellites amd/or reception.

Hi JJB, thanks for your reply.  Yes, I've seen if I take off with limited satellites then I have a flight altitude limit (92ft) and as I'm flying it will update the HP mid flight resulting in a large HP difference between the actual and the estimated.  I've learned that the hard way.  

I'm in the process of stripping out the GPS coords at take off and at HP drift to try to see what's going on.  Interestingly, the D value slowly increases as the MA2 hovers but is not duplicated in the GPS data.  I'm flying with 13 satellites visible.

djiuser_Craig Posted at 12-27 08:39
Hi JJB, thanks for your reply.  Yes, I've seen if I take off with limited satellites then I have a flight altitude limit (92ft) and as I'm flying it will update the HP mid flight resulting in a large HP difference between the actual and the estimated.  I've learned that the hard way.  

I'm in the process of stripping out the GPS coords at take off and at HP drift to try to see what's going on.  Interestingly, the D value slowly increases as the MA2 hovers but is not duplicated in the GPS data.  I'm flying with 13 satellites visible.

Flying away with low sats and reception is often in OPTI mode, height is than limited.
Not wise to do, if you loose visual reference that drone into ATTI mode!.

The moment reception gets to 4 bars and in general 7 or 8 sats > HP is set.
Not always a steady hover with low sats, so be carefull!

I never exprerience a drift of HP, once set is set  and distance to HP is calculated oke all the time.

But curious what you will find out about this. If possible fly with a screen recorder active.

cheers
JJB

Is this a common error where the exact RTH point will drift?
The recorded home point will never drift.
Even if the homepoint is accurately recorded, it's common and normal for the RTH autoland to be +/- a metre or two because that's the accuracy of consumer GPS.
If you launch from a location where the drone cannot get unobstructed  GPS reception, it won't be able to record an accurate homepoint, and landing in the same area could also have accuracy issues.

For precision landing, I almost always hover about 20 meters high for a few seconds after takeoff and before flying out. If I do that, the RTH is nearly always flawless. If not, the landing point can vary up to 7-8 feet  for me.

Labroides Posted at 12-27 13:53
Is this a common error where the exact RTH point will drift?
The recorded home point will never drift.
Even if the homepoint is accurately recorded, it's common and normal for the RTH autoland to be +/- a metre or two because that's the accuracy of consumer GPS.

Okay, this makes sense.  So then it's GPS errors both ways (takeoff & landing) that is creating the landing point variance.  That sounds like what you are saying.  Thanks for the response.

GaryDoug Posted at 12-27 14:05
For precision landing, I almost always hover about 20 meters high for a few seconds after takeoff and before flying out. If I do that, the RTH is nearly always flawless. If not, the landing point can vary up to 7-8 feet  for me.

Okay, good to know.  I'll try that for my next flight.  Thanks for the tip!

djiuser_Craig Posted at 12-27 14:15
Okay, good to know.  I'll try that for my next flight.  Thanks for the tip!

I should add that this process needs a distinctive target on the ground or a unique set of objects around. The MA2 stores an image of the ground at takeoff and uses it to determine the exact landing spot. I use a landing pad with contrasting markings, one side for day and the other for night, although I don't really see much difference in use.

GaryDoug Posted at 12-27 14:22
I should add that this process needs a distinctive target on the ground or a unique set of objects around. The MA2 stores an image of the ground at takeoff and uses it to determine the exact landing spot. I use a landing pad with contrasting markings, one side for day and the other for night, although I don't really see much difference in use.

I was wondering if that also might be a factor, so I ordered a H landing pad and hoping it arrives tomorrow.  One last question since this happened to me once and I'm new at this.  One time my MA2 set a new homepoint quite a ways away from my house and I had to manually steer it back in.  Is there a way to "reset" your home point?  Either off  the DJI Fly app or the controller?  Basically force it to use my location GPS coords and not where it thinks RTH is.

djiuser_Craig Posted at 12-27 14:25
I was wondering if that also might be a factor, so I ordered a H landing pad and hoping it arrives tomorrow.  One last question since this happened to me once and I'm new at this.  One time my MA2 set a new homepoint quite a ways away from my house and I had to manually steer it back in.  Is there a way to "reset" your home point?  Either off  the DJI Fly app or the controller?  Basically force it to use my location GPS coords and not where it thinks RTH is.

Yes, resetting the HP is in the Fly app menus. I believe you can use the map feature also instead of flying back but I have never used it that way.

GaryDoug Posted at 12-27 14:27
Yes, resetting the HP is in the Fly app menus. I believe you can use the map feature also instead of flying back but I have never used it that way.

Good to know, thanks again.

I have had the Home Point in accurate when not waiting for a precision satellite lock.  You will see the satellite indicator in the right upper corner change to white and have more than 9 satellites.  It is very unlikely that the actual GPS location is drifting but more than likely that taking off before the Home Point is set causes the Home Point to be accurate.  GPS interference is extremely rare with precision satellite lock outdoors.

GaryDoug Posted at 2020-12-27 14:22
I should add that this process needs a distinctive target on the ground or a unique set of objects around. The MA2 stores an image of the ground at takeoff and uses it to determine the exact landing spot. I use a landing pad with contrasting markings, one side for day and the other for night, although I don't really see much difference in use.

Hi Gary, I wanted to circle back on this point you made.  The ground target is not working with my MA2.    The drone will land on it and sometimes a few feet away from it.  That and the landing HP drift I'm starting to wonder if my drone has some issues?