Yes I did check that the compass and map matched, and it has only been calibrated when it said to do so on initial purchase.
The flight was meant to be a quick downhill trip to film some canal and river mill scenes and back. I was aware that behind me but nowhere near my intended course were a double row of pylons, however when I tried to fly it back and the counter went down and then up I had passed my position whilst still 200m away and then inadvertantly crossed over the power lines, so when I tried RTH it might be possible that the double row affected the compass which is why it never came home, Who knows!
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I’ve flown close to power cables without suffering any ill effect.
What was the RTH height set to? Sufficient to clear the cables?
… or, were you high enough to clear them when you lost control? … since it would stay at that height for RTH, not descend to the set height.
It was high enough to go over the top, but I can think of no other reason for it not to come home.
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How old was the Mavic mate?
Have you contacted DJI? They are sometimes not helpfull when the flight record ends abruptly but have seen a few cases where it’s been replaced under warranty.
OK - let’s add some meat to this compass discussion. (It’s taken me an hour to locate a video I took over 4 years ago.)
Back then, when people were having this same compass calibration discussion after each flyaway (very frequently), I carried out a bit of an experiment with my P2.
The compass on the P2 is (should be) mounted on one of the landing-gear legs … and when I changed the rather fragile P2 legs for some more robust carbon fibre ones (that, importantly, also provided better ground clearance for the H33D gimbal), I had to relocate the compass.
Everyone was saying I HAD to recalibrate it! So, this got me interested to find out what would happen if I didn’t. And it flew without an issue.
I became more intrigued … so I undid the cable-tie used to hold the compass onto the bracket on the leg, so that it was dangling totally free …. AND out of the alignment it held when on the previous, and new, legs … and wobbling about in the downdraft.
Again, it flew … without an issue … and hovered as accurately as it ever did. (Video below.)
I tried RTH, and it flew straight to me over a distance of about 400m (the size of the field - RTH height set to 5m - so if it went off at a tangent I’d see which bushes/trees it went into).
Whilst I don’t have video of the RTH exercise (I wanted to hold the controller just in case!), I do have video of it hovering, below, on quite a windy spring day.
The dangling compass is marked in this frame-grab, and as it should be fixed in the other two photos that I’ve just taken.
Video:
Note, also, powerlines in the background that I’ve flown VERY close to - specifically to find out if it affected the P2’s stability or compass.
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Only thing worth mentioning is the P2 having a single magnetometer and Mavic having dual.
It’s not true redundancy as that would need 3 but allows mavic to detect errors by comparing the 2 against IMU calculated heading.
If you add anything to Mavic it will normally give compass error as it affects one compass more than other. You might also see it yaw without input as it tries to resolve issue itself.
I’ve found the odd time I’ve removed tracker and forgot to calibrate it lets me take off. I can fly in a straight line but the first time I yaw it goes nuts as the compass does not match what IMU has calculated. It then quickly drops into ATTI mode.
It’s a good system to be honest and works quite well.
The general consensus is that the dual compass has cut down on many of the compass errors with previous models.
The point I was making is that (even with only one compass) the P2 happily performs with the compass in an undeniably wonky state.
This only shows how (relatively) unimportant calibrating the compass is.
If it WAS critical, my P2 should have been all over the place, and RTH a joke.
Ergo - one shouldn’t worry as much about it as many do.
I’ve known of people that recalibrate for EVERY flight … even after a battery change at the same location.
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Yeah agreed