Fixing DJI's Compass Problem

[Brandon89]

Hey guys,

just received my P2 with H3-3d. Also having a problem with compass calibration. ( East coast of Australia). My problem is slightly different, didn't want to start a new thread.

My problem: After the first 360 of the compass dance, when putting the p2 into nose down and commencing the next 360 degree spin, at completion, I get the fast blinking RED lights. can't seem to find any info on this.
When flying, in GPS mode, its quite unstable and won't hold position ( i think this is linked to the compass calibration)

I have reflashed firmware, and calibrated the IMU (advanced) , any other help would be appreciated!

cheers

 

[ianwood]

OK - so it looks to be about 22 - 23 degrees off, with a declination of about 13 degrees in LA. Did you pull the data for a course lock flight?

Not yet. And I should point out the above test is only a GPS plot. The heading that I drew is not based on data but my estimation. Reason being is I am still hunting some of this elusive data. Course lock heading would be good but haven't found it yet. I can get a heading from the raw compass data but I can't yet do any tilt compensation as I am still working out the right source for pitch and roll. I have raw accel and gyro numbers but I would rather not try to guess DJI's specific algorithm.

So I lined up as best I could with due East for this test. I got a magnetic compass heading of 79 on level ground so roughly a true heading of 91 - 92 degrees. The average course over ground from the GPS in the middle of the forward movement (>2m/s speed) was 68.25 so your estimation is spot on.

Hopefully, I'll be able to pull out more interesting information from the decode as I break it down. I'd really like to see DJI's computed compass heading. I am staring at reams of floats trying to correlate them to an OSD recording for things like pitch and roll. Anyone who has experience reverse engineering binary data structures is welcome to help! Here's what it looks like:

The is an Naza 0910 message stream (CAN frames removed). It has (known data in blue, green is unknown or unused) motor speeds, RC channel values, home location (can't find IOC yet!), ATTI pitch/roll, computed elevator, aileron and throttle, batt pct, voltage:

This is an OSD 0210 message (again CAN frames removed). It is in green excluding the header, the blue messages are gyro messages. The OSD message has GPS data, barometer (computed), raw accelerometer, raw compass, raw gyroscope and a bunch of floats that I can't decipher yet:

 

[Bigbells]

My problem: After the first 360 of the compass dance, when putting the p2 into nose down and commencing the next 360 degree spin, at completion, I get the fast blinking RED lights. can't seem to find any info on this.
When flying, in GPS mode, its quite unstable and won't hold position ( i think this is linked to the compass calibration)



cheers

I would think that the calibration failed, except that should be fast blinking red AND yellow, alternating, rather than just red. Did you try repeatedly to re-set and re-calibrate? It is not unusual for a calibration not to "take", requiring doing it again.

Do you wait for and then get the slowly flashing green lights on the rear arms? If you don't, then you're not actually flying in GPS mode regardless of the S1 switch position on the remote control.

 

[Brandon89]

My problem: After the first 360 of the compass dance, when putting the p2 into nose down and commencing the next 360 degree spin, at completion, I get the fast blinking RED lights. can't seem to find any info on this.
When flying, in GPS mode, its quite unstable and won't hold position ( i think this is linked to the compass calibration)



cheers

I would think that the calibration failed, except that should be fast blinking red AND yellow, alternating, rather than just red. Did you try repeatedly to re-set and re-calibrate? It is not unusual for a calibration not to "take", requiring doing it again.

Do you wait for and then get the slowly flashing green lights on the rear arms? If you don't, then you're not actually flying in GPS mode regardless of the S1 switch position on the remote control.

Thanks! Yeah it flashes red in Naza mode and red yellow phantom mode. When plugged into the computer the compass raw values remain fixed ( not frozen, but fluctuate by +- 2/3 ). Even if I spin the unit in any direction. I think the compass is faulty

 

[Bigbells]

Thanks! Yeah it flashes red in Naza mode and red yellow phantom mode. When plugged into the computer the compass raw values remain fixed ( not frozen, but fluctuate by +- 2/3 ). Even if I spin the unit in any direction. I think the compass is faulty

You're very welcome.

I'm trying to figure out if this is all new to you or if you're experienced. Some of what you say seems to indicate that you're struggling with this for the first time, so please let me know if I'm telling you stuff you already know.

Spinning the Phantom while doing an IMU calibration will invalidate the calibration. Also, the number that is most important is the big number, bottom right of the screen. It should be (if I remember correctly) between 750 and (I'm guessing here because I don't remember) 2450(?).

 

[Brandon89]

Thanks! Yeah it flashes red in Naza mode and red yellow phantom mode. When plugged into the computer the compass raw values remain fixed ( not frozen, but fluctuate by +- 2/3 ). Even if I spin the unit in any direction. I think the compass is faulty

You're very welcome.

I'm trying to figure out if this is all new to you or if you're experienced. Some of what you say seems to indicate that you're struggling with this for the first time, so please let me know if I'm telling you stuff you already know.

Spinning the Phantom while doing an IMU calibration will invalidate the calibration. Also, the number that is most important is the big number, bottom right of the screen. It should be (if I remember correctly) between 750 and (I'm guessing here because I don't remember) 2450(?).

Thanks again. Yeah new to quads , flown nitro helis for a while. But while waiting for the P2 I had a lot of time to read up.
Have had no problems calibrating the imu.

It's just the compass , which I think is faulty , the last value (MOD) sits at around 1480. Whilst X,Y,Z barely move at all

 

[Bigbells]

Thanks again. Yeah new to quads , flown nitro helis for a while. But while waiting for the P2 I had a lot of time to read up.
Have had no problems calibrating the imu.

It's just the compass , which I think is faulty , the last value (MOD) sits at around 1480. Whilst X,Y,Z barely move at all

That's the way it's sposta be. Those are good readings, not indicative of any problem.

 

[Brandon89]

Thanks again. Yeah new to quads , flown nitro helis for a while. But while waiting for the P2 I had a lot of time to read up.
Have had no problems calibrating the imu.

It's just the compass , which I think is faulty , the last value (MOD) sits at around 1480. Whilst X,Y,Z barely move at all

That's the way it's sposta be. Those are good readings, not indicative of any problem.

Thanks, for some reason I thought as you rotated the phantom the compass raw data would change , and be constant with the other gyro figures when stable on a desk

 

[ianwood]

When plugged into the computer the compass raw values remain fixed ( not frozen, but fluctuate by +- 2/3 ). Even if I spin the unit in any direction.

Totally normal. If you need further help on calibration, please start a new thread as this one is focused on a specific problem unrelated to calibration.

 

[pbmac]

I have the same problems with hooking to the right, drifting to the right while flying straight and the toilet bowl effect. I am in Maine and my magnetic variation is 16° W. I have a Vision 2 and a Vision 2+. Both exhibit the same problems.

 

[ianwood]

The 18 Hooks of the Compass

Another visualization. Follow the numbers and you can see how the hook cleans up slowly as you fly. Virtually no yawing was done in this flight. Just elevator and aileron, and only one at a time. You can see that hooks 1-9 are pretty considerable but by hook 18, there is barely a hook anymore.

 

[onfourblades]

Re: The 18 Hooks of the Compass

Another visualization. Follow the numbers and you can see how the hook cleans up slowly as you fly. Virtually no yawing was done in this flight. Just elevator and aileron, and only one at a time. You can see that hooks 1-9 are pretty considerable but by hook 18, there is barely a hook anymore.

Great Job with the Visuallization.... It helps me SEE the problem

Any other test u need me to do? dont hesitate!
have Great day guys and gals
keep the blades spinning

 

[Erwan]

Hi there,

Newbie on the forum but unfortunately same problem so you can add me to the list.

Declinaison -20 (réunion island near Africa)

Phantom 2 vision ( since 2/3 months)
Hooking to the right when stick is to the front.
Hoovering also when take off, as the flight goes better flying.

i didn't do the firmware update already as i read some issues but will go on it as i received new H3-3D so i will go through the software make again a calibration and hope that's fix it…**** need to fly straight finally !

:roll:

 

[azsean]

Hi guys,
I live in Brazil (Brasilia: -21 deviation). I was having some trouble controlling the phantom a few times and now, after some research, I know it´s due to this compass problem. Specially at the beginning of the flight, when I point straight it goes to the right pretty badly and when I let go the sticks, it rotates around (I think this is what you call TBE). After 5 or 6 minutes into the flight it seems to improve a lot.
One time, during the first few flights, I flew it into a Tree and it got stuck up there. I had to call firefighters to recover it and fortunately it didn´t fall in a lake by the tree.
So.. I am waiting for a fix ASAP from DJI. It´s ridiculous they haven´t fixed such an inportant issue yet.

One more thing.. After updating the firmware to 3.0 and enabling Nasa Mode, I noticed some LED messages that I´m unable to figure out the meaning. After I let it warm up and get home position, it blinks 4 times green (slow blinking) and then around 8 times red (fast blinking), 4 times green, 8 times red, and so on... Anybody knows what this means?

PS: I tried calibrating everything (stick, basic, advanced, compass, etc... ) but it doesn´t change the LEDs.


Luciano and Sana,

THanks a lot.
Luciano.

Hi luciano, when you switched from phantom mode to naza mode the leds color chance, getting green color then 3-4 red color is normal, it means its getting satellites, after a while it will go all green, that means you have a good amount of satellites

Sana

I received my P2 yesterday and this morning before my first flight I updated the firmware. I went outside, away from things that would cause interference and I also get the 2-3 green flashes then rapid red led's. I am still in Phantom mode, not Naza therefore I don't think that has anything to do with this particular code. I'm working with the dealer to figure it out. I just calibrated the IMU basic then advanced. When I first tried this, it gave me a warming that the MU temperature was too high to do the calibration. I tried it again and it worked. I also get a GPS error 27 randomly when I am connected. I click ok and it gives me the warning in the bottom left corner then all of a sudden it is gone.
Maybe I'll open up the shell to see if all my cables are connected properly

 

[ashleyg]

azsean you are in an airport zone close to, or in restricted area, I believe based on the leds

 

[lucianopacheco]

THe last flights I had I didn´t get the series of 8 red blinks after the 4 greens. Now, only the 4 greens. I didn´t do anything to change that...

 

[ianwood]

THe last flights I had I didn´t get the series of 8 red blinks after the 4 greens. Now, only the 4 greens. I didn´t do anything to change that...

As this thread is really only read by people focused on the compass issue, you might want to create a new post to look at this issue you have with the lights.

 

[MJB]

I believe I have experienced this issue in Vancouver BC. Toilet bowl, hooking, which also caused me to slam into a small tree and damage the propellers.

 

[Gary E]

Add me to the compass hooking left problem list. Compass in original factory set position. Takes right forward stick to fly straight.

P2 is a month old. Compass correction here is 15 degrees (Southwestern Oregon).

 

[Doono]

J hook to the left straight out of box.

Phantom 2 Vision Plus
Charged it up, calibrated in open field, latest iPhone app. Declination +12. It hovered beautifully, waited around 4 mins, stick straight forward and it started to go left around 30 metres. Let go and it hooked even more. Can't report accurately on TB yet.
I did not connect Phantom or controller to a laptop.