2nd compass DJI MP2
- Thread starter Mikeg
- Start date
They went back to two IMUs for the M2, presumably based on use data that showed that a second IMU provides a useful backup but that the presence of two compasses rarely made much difference.
Thanks for that and I totally understand their point of view. But, would you like to have seen a second compass as back up or do you think it is totally unnecessary? I suppose that to be honest just gave me a warm feeling and if I had been asked to pay an extra £20 for it I wouldn’t of minded .
Kilrah
Well-Known Member
On the Mavic Air they removed the 2nd compass and replaced it with orientation estimation based on the avoidance sensors. Probably doing the same on M2. Better to have 2 different sources of info than 2 of the same (which can be disturbed simultaneously by the same thing and you never know).
It's a fine idea in principle. However, having analyzed a lot of flight logs with compass problems, I've almost never seen the backup compass take over, so I'm not sure there was much to be gained.
Exactly this. Overall the dual compass system in the original MP didn't really help, or at least it didn't reduce the number of compass-related accidents. Worth noting that the Inspire 2 was released around the same time and only has one compass, and all DJI drones since have had just the one compass as well.
DJI have made some mistakes with compasses however. Early M200/210s had compass issues though I think this was mostly resolved by firmware (the wiring inside an M200 is a total mess though, which doesn't help). The massive Wind 8s have also had lots of issues with the internal compasses, to the point that DJI started sending out external compass upgrade kits to customers...
Just make sure the compass is calibrated when it should be and you'll be fine.
Agreed. Although even more important than calibration is to ensure that there is no local magnetic interference when the aircraft powers up, because that's when the IMU yaw value is initialized. If that is wrong then after takeoff the FC is likely to lose control of the aircraft. The worst that I've seen from an out-of-calibration compass is slight uncommanded yaw excursions.
