Forward Flight Tracking Left

[BenDronePilot]

I see a similar issue and it's always subtle enough that I think that perhaps I'm not quite as aligned "straight ahead" as I thought. I might drift five yards off course for a hundred yard straight line flight and that's straight enough for most work... I've also recalibrated the compass with no change in tracking.

I suspect it's coupled to another odd behavior that I see - I can fly 'stick forward' in a (reasonably) straight line but when I let the stick go and the Phantom 'coasts' to a stop it always drifts left - sometimes by as much as ten or twenty yards if I was moving at a good rate of speed. I suspect it's an artifact of the hand-off from inertial guidance to GPS position hold but I have no insight to the inner workings of their software.

Do you see a similar drift at the end of a straight line run?

I noticed my phantom is now drifting to the right. Today I did both a basic and advanced calibration on a straight level surface and a new compass calibration and it's still drifting to the right when doing straight forward flight, then when I let go of the stick it drifts a little further. On the flip side it goes in a straight line back and side and has a rock solid hover. Really strange.

 

[dcozad]

When I purchased and the first 10 flights the P2V flew like an arrow forward and back. I noticed it felt weird in flight about that time and then I tried to fly along a row of palms which were straight. It drifted left 10 degrees or so and then further left as it slowed for position. Flying backward it drifted right, about 10 degrees and at slowing drifted further right. We happened to have the AMA show in Ontario and chatted with the Aerial Media Pros guys who looked at me grinning and said Compass Calibration. :lol: I said that I had and they said do it again. along with an advanced IMU Calibration.

I carefully leveled and did the IMU Calibration and the numbers looked OK, based on the other comments posted. I then took it out to the large field in my neighborhood where I first did the calibration.......

It did not work. I tried it the other direction both ways. Finally, I went back to the counterclockwise I had used initially and it worked fine. Flies just like the first day. I think there there is some variability in the this and that is why the AMP guys said to do it each time and do it till it flies right. I write this not to complain but to give hope that this may be an intermittent issue fixable by a few calibrations and to add to the collective knowledge.

 

[EyeUpHigh]

Hi all, It's early days for me yet but I believe I might be experiencing the 'tracking slightly left' issue. Has anyone seen this reference from Naza-M pages? http://wiki.dji.com/en/index.php/Naza-M_GPS_Attitude_Mode_Flight
I've not made the adjustment myself but thought it might be worth mentioning here.
Cheers.

My P2V is currently down at DroneFly for this very problem (I was tracking over 20 degrees to the left, IMU and compass calibrations did nothing) and had seen this note in the Naza-M Quick Start Guide and brought it to the attention of the guys at DroneFly.

I'm a bit dubious about this, though, and here's why: In theory, GPS is only about position, not orientation. You can deduce your orientation and speed by taking two measurements while in motion but a single GPS snapshot can only give you a point in space. Rotating the antenna should have no effect because the timing of the GPS signals reaching the receiver aren't affected by the orientation of the antenna. That's why mobile phones and Phantoms also have magnetic field sensors - to provide navigational information that you wouldn't otherwise have. Unless DJI has build some sort of hybrid GPS antenna that also includes an inertial sensor there'd be no need to orient it an any particular direction.

Hopefully somebody else here is more experienced at building multi-rotors and knows about the GPS antenna design...

 

[HollyFlier]

Hi all, It's early days for me yet but I believe I might be experiencing the 'tracking slightly left' issue. Has anyone seen this reference from Naza-M pages? http://wiki.dji.com/en/index.php/Naza-M_GPS_Attitude_Mode_Flight
I've not made the adjustment myself but thought it might be worth mentioning here.
Cheers.

My P2V is currently down at DroneFly for this very problem (I was tracking over 20 degrees to the left, IMU and compass calibrations did nothing) and had seen this note in the Naza-M Quick Start Guide and brought it to the attention of the guys at DroneFly.

I'm a bit dubious about this, though, and here's why: In theory, GPS is only about position, not orientation. You can deduce your orientation and speed by taking two measurements while in motion but a single GPS snapshot can only give you a point in space. Rotating the antenna should have no effect because the timing of the GPS signals reaching the receiver aren't affected by the orientation of the antenna. That's why mobile phones and Phantoms also have magnetic field sensors - to provide navigational information that you wouldn't otherwise have. Unless DJI has build some sort of hybrid GPS antenna that also includes an inertial sensor there'd be no need to orient it an any particular direction.

Hopefully somebody else here is more experienced at building multi-rotors and knows about the GPS antenna design...

As I understand it, the normal Naza-M flight system has both the compass and GPS unit mounted in the 'puck'. The P2V, obviously has them separate. I really don't think rotating the GPS unit on the P2V will have the same effect as doing it on a normal Naza-M system. Most of the fixes I've read about for the Phantoms involve shimming the compass to achieve the same effect. Just my 2 cents...

 

[Driffill]

Hi all, It's early days for me yet but I believe I might be experiencing the 'tracking slightly left' issue. Has anyone seen this reference from Naza-M pages? http://wiki.dji.com/en/index.php/Naza-M_GPS_Attitude_Mode_Flight
I've not made the adjustment myself but thought it might be worth mentioning here.
Cheers.

My P2V is currently down at DroneFly for this very problem (I was tracking over 20 degrees to the left, IMU and compass calibrations did nothing) and had seen this note in the Naza-M Quick Start Guide and brought it to the attention of the guys at DroneFly.

I'm a bit dubious about this, though, and here's why: In theory, GPS is only about position, not orientation. You can deduce your orientation and speed by taking two measurements while in motion but a single GPS snapshot can only give you a point in space. Rotating the antenna should have no effect because the timing of the GPS signals reaching the receiver aren't affected by the orientation of the antenna. That's why mobile phones and Phantoms also have magnetic field sensors - to provide navigational information that you wouldn't otherwise have. Unless DJI has build some sort of hybrid GPS antenna that also includes an inertial sensor there'd be no need to orient it an any particular direction.

Hopefully somebody else here is more experienced at building multi-rotors and knows about the GPS antenna design...

As I understand it, the normal Naza-M flight system has both the compass and GPS unit mounted in the 'puck'. The P2V, obviously has them separate. I really don't think rotating the GPS unit on the P2V will have the same effect as doing it on a normal Naza-M system. Most of the fixes I've read about for the Phantoms involve shimming the compass to achieve the same effect. Just my 2 cents...

+1

 

[GMANNZ]

Took my Vision out yesterday with the hopes of figuring out the left tracking and drifting issue. After religiously calibrating 4 different times, she was still drifting and tracking left - no change.

Then, in a moment of brilliance ( :roll: ) I decided to rotate the Vision in the opposite direction during calibration (I always rotate to the left, horizontally and vertically, only because that's the way Colin does it on the YouTube video). I'm not going to try to figure out why, but changing the rotation to the right WORKED!!!!

Oh man, straight flights are sooooo much nicer. I hope this works for anyone else with this issue. Chime in if it does.

Interesting idea ???? did actually see a question earlier asking whether down at bottom of planet like here in NZ did TBE etc reserves direction LOL
Have same probelm here exactly as you describe, everything works pefect except that left tracking ... will try your suggestion and see if works for me as I have nothing left to try ....

 

[nhoover]

My P2V flew straight and true for its first 20 flights. Then I added a Flytrex module and on the first flight today it was clearly not ok. The left drift is as others are describing. So I landed and calibrated in the middle of a field far from any metal. No improvement, but I only did it once and only the standard direction.

I'll try a few more, times and rotating both ways until it's fixed I guess. For those 20 perfect flights I only calibrated it once before the first flight although they were all within 25 miles of home.

 

[Pull_Up]

My P2V flew straight and true for its first 20 flights. Then I added a Flytrex module and on the first flight today it was clearly not ok. The left drift is as others are describing. So I landed and calibrated in the middle of a field far from any metal. No improvement, but I only did it once and only the standard direction.

I'll try a few more, times and rotating both ways until it's fixed I guess. For those 20 perfect flights I only calibrated it once before the first flight although they were all within 25 miles of home.

Although I'm generally in the "don't calibrate if everything's ok" camp, if you add anything to the aircraft, update firmware or have to take the lid off for any reason then I'd always calibrate before first flight subsequently. Adding the Flytrex might well change the status quo of the magnet field the compass detects, and also using a screwdriver right up close with it to get the lid off might have tweaked it.

If a good, clear compass recalibration doesn't work, try plugging it in and running an IMU calibration, even if it says it doesn't need it. Have a look at the compass values and make sure they are within limits. My Vision showed absolutely no side-effects from adding a Flytrex after calibrating the compass after the initial installation - hopefully you can get yours cleared.

 

[obiwan_pierogi]

Someone put a video on youtube.. Mine does the exact same thing.. Gives you the feeling you've lost control of the copter, for a few seconds.. Maybe it's a precession thing.. http://www.youtube.com/watch?v=DHuzmBxej5M

 

[Mossie]

As a rookie flier who at the moment has a Vision that seems to fly OK, I have have been following all these posts with interest in anticipation of the day when my copter doesn't fly as it should.

Of all the posts I've read about copters not flying straight, hovering correctly, erratic flying, etc etc, I can't recall seeing a single one where IMU recalibration or compass calibration has solved anybody's problem. Maybe there's some pieces of hardware in there that isn't up to the job and component replacement is the only answer.

 

[obiwan_pierogi]

I'm tending to agree.. You watch guys like Colin on the youtubes.. And they get on the video.. Do their compass calibration, without breaking a sweat, or worried about their rings or watches.. Zip, Zip, Zip.. Then off they fly, without a glitch.. Copter stands rock still, while hovering-- even in a wind.. And then you have people like myself, doing multiple compass re-calibrations, and IMU recalibrations.. And being so ****, with levels, and avoiding everything metallic.. Ie: walking out in the bush to perform the compass dance.. And the copter still flies like crap.. It just won't hover, or fly the way colin's does.. Could it be something as simple as a faulty electronic part?

 

[obiwan_pierogi]

What gives? Check this guy's video out that was on the dji facebook site.. Especially at the end.. His unit holds rock solid.. No drifting left, even after a high-speed straight run.. It stops on a dime. Even from new, my copter was never this stable.. http://www.youtube.com/watch?v=vT-7bO0IK5U

 

[gunslinger]

What gives? Check this guy's video out that was on the dji facebook site.. Especially at the end.. His unit holds rock solid.. No drifting left, even after a high-speed straight run.. It stops on a dime. Even from new, my copter was never this stable.. http://www.youtube.com/watch?v=vT-7bO0IK5U

He may have a dozen satellites locked.

-slinger