Compass off a few degrees

[Rob Levine]

I have two P4P v2.0 drones...on one of them I can't get the compass to calibrate correctly. I CAN do the calibration, and it says ok to fly. BUT - after calibration (many times) I can't get the green arrow to point to the correct direction after the home point is set. It aims a few degrees off. Any suggestions? Just being off a few degrees is screwing up my litchi flights.

 

[Alex Baxter]

Have you tried an IMU calibration beforehand?

 

[Rob Levine]

Have you tried an IMU calibration beforehand?

Not yet. I just tried another calibration where instead of holding the drone then rotating my body around during calibration I kept the drone where it was on the ground and rotated at the same point - and it seems to have worked? How do other people do the calibration?

 

[Oso]

I have two P4P v2.0 drones...on one of them I can't get the compass to calibrate correctly. I CAN do the calibration, and it says ok to fly. BUT - after calibration (many times) I can't get the green arrow to point to the correct direction after the home point is set. It aims a few degrees off. Any suggestions? Just being off a few degrees is screwing up my litchi flights.

Are you using the same mobile device for both drones?
Have you checked the compass in your mobile device (not your AC) to see if it needs to be calibrated?

 

[Rob Levine]

Are you using the same mobile device for both drones?
Have you checked the compass in your mobile device (not your AC) to see if it needs to be calibrated?

Yeah same device. See my response above - I may have figured it out. Instead of rotating my entire body while holding the drone outstretched with my arm I rotated the drone in place near the ground - which seems to have worked.

 

[Oso]

How do other people do the calibration?

I haven’t calibrated the compass in years, but when I do a calibration I rotate with the drone close to my body. No outstretched arms.

 

[Deleted member 62848]

When I do calibration I just hold and turn drone around while I stay still ,never fail me,,looks more professional aswell if have crowd around

 

[Meta4]

Yeah same device. See my response above - I may have figured it out. Instead of rotating my entire body while holding the drone outstretched with my arm I rotated the drone in place near the ground - which seems to have worked.

I'm not sure that would have made any difference.
Recalibrating the drone's compass shouldn't make any difference to the drone's alignment relative to magnetic north.
Compass calibration has nothing to do with the alignment of the drone and if the drone was hovering in place normally, recalibrating would have had no effect at all.
Compass calibration is only affected by the drone's internal magnetic environment, not the world around the drone.

I'm having trouble understanding what the original problem was and how some mystery condition could mess up a Litchi mission.
Litchi missions involve fixed waypoints with the drone using GPS to travel from waypoint to waypoint.

 

[Rob Levine]

I'm not sure that would have made any difference.
Recalibrating the drone's compass shouldn't make any difference to the drone's alignment relative to magnetic north.
Compass calibration has nothing to do with the alignment of the drone and if the drone was hovering in place normally, recalibrating would have had no effect at all.
Compass calibration is only affected by the drone's internal magnetic environment, not the world around the drone.

I'm having trouble understanding what the original problem was and how some mystery condition could mess up a Litchi mission.
Litchi missions involve fixed waypoints with the drone using GPS to travel from waypoint to waypoint.

Right but isn't orientation affected by the compass? I had a problem in Litchi where the camera aim was off a few degrees but the mission ran correctly. When I start up the drone and get the home point I always check to see if the arrow is pointing the right way, because if it's not I heard this means the compass is not correct. In this case it was off a few degrees. It was a mission I had run successfully perhaps a dozen times. I suppose the problem could be somewhere else...

 

[Meta4]

Right but isn't orientation affected by the compass? I had a problem in Litchi where the camera aim was off a few degrees but the mission ran correctly. When I start up the drone and get the home point I always check to see if the arrow is pointing the right way, because if it's not I heard this means the compass is not correct. In this case it was off a few degrees. It was a mission I had run successfully perhaps a dozen times. I suppose the problem could be somewhere else...

If there was a problem with your compass, I'd think that it would show up in flight problems that couldn't easily be ignored.
But now that your Phantom is definitely running properly, there's no need to recalibrate the compass unless you modify the drone.

 

[Phil Crossley]

When I do calibration I just hold and turn drone around while I stay still ,never fail me,,looks more professional aswell if have crowd around

I think the new rules say you have to do it with your drone held down at knee level; penalty stroke if held out at arm's length...

 

[bsartist]

Could he be describing the inability to fly straight and “crabbing” that a number of people (including myself) experience? I’m constantly having to apply aileron to counteract and attempt to get it to fly straight.

 

[Meta4]

Could he be describing the inability to fly straight and “crabbing” that a number of people (including myself) experience? I’m constantly having to apply aileron to counteract and attempt to get it to fly straight.

Ah yes ... that affected a number of V2.0 owners.
Did DJI fix it eventually with a firmware update?

 

[bsartist]

Ah yes ... that affected a number of V2.0 owners.
Did DJI fix it eventually with a firmware update?

I have the problem on a V1

 

[Deleted member 62848]

I think the new rules say you have to do it with your drone held down at knee level; penalty stroke if held out at arm's length...

Yeh but no good if cables or steel buried below,you can still hold at arms length, I think that just keeps it away from your body,,makes no difference if close or arms length unless you got a pacemaker or another phone in you pocket that might interfere

 

[Rob Levine]

So a little more info here...went back and flew the same Litchi mission...If I move the drone even a few hundred yards the compass goes off a few degrees, and the mission is a little off...If I calibrate the compass, turn the drone off and on then the compass gets set correctly and the mission runs correctly. Thinking I need a repair....adding...the software doesn't prompt a calibration but the arrow points a few degrees off

 

[Meta4]

If I calibrate the compass, turn the drone off and on then the compass gets set correctly and the mission runs correctly.

This part doesn't make sense.
If your compass was properly calibrated last week, it should still be properly calibrated this week unless you've modified the drone since last week.
The compass doesn't go off and doesn't require frequent recalibration.
I have never calibrated the compass on my work Phantom and after 4.5 years and >7000 kilometres, it still flies perfectly.

Thinking I need a repair....adding...the software doesn't prompt a calibration but the arrow points a few degrees off

The orientation display indicating a few degrees off (assuming you could accurately use it to tell a few degrees) suggests some steel close by that's slightly deflecting the drone's compass.
I'm still not seeing how your Litchi mission would be affected.
Can you explain in detail what problem this causes?
Does the drone fly straight in manual flight or does it wander off course?

 

[Rob Levine]

This part doesn't make sense.
If your compass was properly calibrated last week, it should still be properly calibrated this week unless you've modified the drone since last week.
The compass doesn't go off and doesn't require frequent recalibration.
I have never calibrated the compass on my work Phantom and after 4.5 years and >7000 kilometres, it still flies perfectly.


The orientation display indicating a few degrees off (assuming you could accurately use it to tell a few degrees) suggests some steel close by that's slightly deflecting the drone's compass.
I'm still not seeing how your Litchi mission would be affected.
Can you explain in detail what problem this causes?
Does the drone fly straight in manual flight or does it wander off course?

A few degrees is just my guess. Maybe five degrees or so? As far as I can tell the drone flies straight - but I can't say for sure because I didn't exactly do that. But in the Litchi mission the aim is off enough to kinda ruin the footage. There is some steel nearby the mission (railroad tracks).

But I don't think that's it because it does the same on the sidewalk leading to my porch (not sure if there's any metal in there). The mission I've been doing is like five miles or so away. I do the first mission after calibration at the fly site. That works after calibration and turn off/on the drone. Then I move about 200 yards to do a mission from the other side of the building. I turn the drone on and get the errant arrow again. I wonder whether that is truly wrecking the mission so I run it. Sure enough - same problem. I bring the drone down, calibrate, off and on, viola the arrow is pointing correctly and the mission runs correctly.

I've been running this mission for a year, and same for outside my house. This is a new problem. I'm open to the suggestion that this is something else, but the fact that a calibration and reboot corrects the problem points to the compass. It's really not a terrible problem since I seem to be able to correct it each time, but I would like to get to the bottom of it. Thanks for your help. I'll take it out tomorrow and try to fly straight.

 

[Meta4]

But in the Litchi mission the aim is off enough to kinda ruin the footage.

In a Litchi mission you program the drone to fly from wherever it is to a waypoint.
Is yours flying toward the waypoint or somewhere else?
How is it ruining the footage?

There is some steel nearby the mission (railroad tracks).

Unless you are within a few feet, the railroad tracks won't have any influence on your drone.

But I don't think that's it because it does the same on the sidewalk leading to my porch (not sure if there's any metal in there).

It's a safe assumption that there will be steel inside concrete structures.
Launching from concrete surfaces is not a good idea.

I do the first mission after calibration at the fly site.

What's thhreason for recalibrating the compass?
It's completely unnecessary

That works after calibration and turn off/on the drone. Then I move about 200 yards to do a mission from the other side of the building. I turn the drone on and get the errant arrow again. I wonder whether that is truly wrecking the mission so I run it. Sure enough - same problem. I bring the drone down, calibrate, off and on, viola the arrow is pointing correctly and the mission runs correctly. ... I'm open to the suggestion that this is something else, but the fact that a calibration and reboot corrects the problem points to the compass. It's really not a terrible problem since I seem to be able to correct it each time, but I would like to get to the bottom of it.

Stop recalibrating the compass.
Thinking that makes any difference is only distracting you from the actual issue.

I've been running this mission for a year, and same for outside my house. This is a new problem.

It would help if you could clearly explain exactly what the problem is because it's still not clear what the drone is doing.

 

[Rob Levine]

In a Litchi mission you program the drone to fly from wherever it is to a waypoint.
Is yours flying toward the waypoint or somewhere else?
How is it ruining the footage?

Unless you are within a few feet, the railroad tracks won't have any influence on your drone.

It's a safe assumption that there will be steel inside concrete structures.
Launching from concrete surfaces is not a good idea.

What's thhreason for recalibrating the compass?
It's completely unnecessary

Stop recalibrating the compass.
Thinking that makes any difference is only distracting you from the actual issue.

It would help if you could clearly explain exactly what the problem is because it's still not clear what the drone is doing.

Here's a rough side by side - top is error. Another mission had similar problem