Fixing DJI's Compass Problem

[ianwood]

And so I am planning a trip across the US. What should I be prepared to see as I travel to areas of greater declination? Increased wandering in forward flight? I will be sure to document my experiences and report back :?:

At -4, you'll see a very mild right hook in the very beginning which will clean up within a minute or so. I just flew my P2 in Chicago where it is also -4. It had the very light right hook and then it flew straight for the rest of the flight which was really nice. In Los Angeles (+12 declination), where I normally fly, I get a pronounced left hook followed by a little TBE. It will not track as straight which makes lining up shots tricky. It takes more than half of the flight for these issues to resolve. It's the same in the Northeast just going the other way.

Make sure when you get someplace new to recalibrate the compass in a safe place.

 

[xtonex]

And so I am planning a trip across the US. What should I be prepared to see as I travel to areas of greater declination? Increased wandering in forward flight? I will be sure to document my experiences and report back :?:

At -4, you'll see a very mild right hook in the very beginning which will clean up within a minute or so. I just flew my P2 in Chicago where it is also -4. It had the very light right hook and then it flew straight for the rest of the flight which was really nice. In Los Angeles (+12 declination), where I normally fly, I get a pronounced left hook followed by a little TBE. It will not track as straight which makes lining up shots tricky. It takes more than half of the flight for these issues to resolve. It's the same in the Northeast just going the other way.

Make sure when you get someplace new to recalibrate the compass in a safe place.

I assume you had your mark ii on in chicage too and was able to pass that data along? The fact it cleans up over the flight tells me this shouldnt be a tough fix for them. Im gonna start timing the clean up on my end here in NY since i dont have a mark ii (i do have a flytrex 2 on the way whenever they ship). I wonder if its not a time thing as much as it is a fly in different directions thing to let the gps help the correction quicker

 

[John Shaw]

I don't want to distract from the formal testing program, but if you want a quick check, I think the clearest way to see the effect is as follows.
Be in NAZA mode.
Carefully line up you phantom with a reference line or aimed at a reference point.
Get your GPS Home Lock and Course Lock.
Take off
Switch to Course Lock
Get the Phantom stabilized over your starting reference point and aimed down your reference line as quickly as practical.
Push only forward elevator (the right stick forward).
The Phantom SHOULD go straight ahead down the reference line toward the reference point.
But... the Phantom will go perfectly straight but at an angle to your reference line at about twice the declination.
This is easier to see quantitatively than TBE, drift or JHook. - but it is caused by the very same problem.
I did my tests on a soccer field because it provides lines and easy references for figuring the angle.
It also makes apparent that course lock is of little value until they get this fixed. I expect in the mean time we could set down the Phantom rotated an equal amount the other way - but that's highly undesirable.

 

[ianwood]

Yes, I am now working through the OSD data from Chicago and comparing it to Los Angeles.

John, I agree. Course lock is the easiest way to see the problem. It shows where the compass thinks it's pointing when you first turn it on. Even in Chicago with only -4 declination, course lock was clearly off by about 10 degrees.

 

[SOproductionsGND]

Hey guys, new Phantom 2 operator here from the Caribbean island of Grenada.

I've also been noticing some drift (hooking) to the right when pushing forward (nose down, is it?). When flying backward, it seems to be fine, though I haven't checked on it fixing itself over time. More recently I've seen it flying tilted, front right(though that may be a separate issue... perhaps can point me in the right direction for that solution?) In any case, I suppose you can add me to that problem. Will fly again very soon to confirm. Flying GPS only, H3-2D and Hero 3+ with mini IOSD and AVL 5.8 wireless transmitter (B&H FPV package)

Actually, here's a video I shot last weekend that may show the issue (and others): https://drive.google.com/file/d/0B6vSzH ... sp=sharing

My Geographical Info and Declination:

Latitude: 12° 4' 36.9" N
Longitude: 61° 42' 17" W
Magnetic declination: -14° 38' WEST
Declination is NEGATIVE
Inclination: 33° 43'
Magnetic field strength: 33191.9 nT

 

[landonkk]

What the...??? That is beyond weird. I just messaged them to tell them it is totally wrong and asked what their source was for that information.

And BTW, I can confirm it does nothing for the compass issue.

Hey ian - just wondering if you ever heard back from B&H on what their anti-interference board description was all about?

 

[gorano]

I have the same problem after upgrading to 3.02 unstabel in the wind drifting of when tryint to flye ina staght line

 

[landonkk]

I have the same problem after upgrading to 3.02 unstabel in the wind drifting of when tryint to flye ina staght line

Where are you located? Does it drift in only one direction, and if so right or left? The 'j-hook' issue is prevalent in all firmware so it shouldn't be "new" since an upgrade. Maybe you are just now noticing it, or maybe it is another problem altogether.

 

[gorano]

i have been flying the dji phantom 2 sins feb 2014 it has been stady in the wind and smoth to controll it maght have had the jhock problem sligtly but it have becom a real problem when i upgraded to 3.02 its like in the video and feels like its out of controll and if the wind is blowind in the same direktion as it jhocks its realy getsgoing fast but it stops after a litel wile an going back almost to the stop point were i letgo of the stick. i have done all the cali i can do in software and compas but no difrent result. i live in sweden btw

 

[ianwood]

Gorano, your problem is likely unrelated to this one. The declination issue occurs on all firmware variations.

 

[RobRuss]

Hey Ian,
great job on trying to get this issue sorted out ... kinda makes the whole experience of flying way too stressful and way too costly in spares.... maybe they (DJI) did this on purpose to ramp up sales of spares.

Flew great out of the box for around 5 flights, then did the upgrade to 3.02 and all hell has broken out since then, same symptoms as described by so many disgruntled PV2 owners on the forum.

I live in Johannesburg South Africa
Latitude: 26° 11' 60" S
Longitude: 28° 4' 60" E
Magnetic declination: -18° 24' WEST
Declination is NEGATIVE
Inclination: -63° 5'
Magnetic field strength: 28351.3 nT

And tried to fly in Durban
Latitude: 29° 51' 0" S
Longitude: 31° 1' 0" E
Magnetic declination: -24° 59' WEST
Declination is NEGATIVE
Inclination: -63° 1'
Magnetic field strength: 28299.3 nT

The flying experience between the two Cities is remarkable to say the least, with virtually zero control for the Durban flight lasting less than a minute and ending in another expensive repair job. No more flying until a fix is found or I will sell my PV2 to someone in the world where they can at least fly it with none of the compass problem headaches.

Do any of the other manufactures of RC crafts have this issue or is just DJI's incompetency?

Also DJI should qualify their RTF sales pitch.... it's not RTF in countries with a high magnetic declination and should be marketed as a RTC (ready to crash) version for these countries.

 

[Andy T]

I have posted that I have this problem previously but I also have some drifting in ATTI mode but not as severe as in GPS mode. Are we 100% sure that if it drifts in atti mode its not a declination issue?

 

[sar104]

I finally had the opportunity and calm weather conditions to flight test the P2 with H3-3D 1.0, Lightbridge and all the latest firmware. Declination is 8.5 degrees west, so I was not expecting to see much effect. No discernible TBE, but significant left hook - probably around 15 m. As expected, it decreased with flying time. Perfectly flyable, but not in tight spaces. Count me in as having the problem.

 

[SilentAV8R]

A thought occurs to me that it appears people want this thing to basically fly itself. I think one reason this did not get noticed by me as much as some others is that I was more or less automatically correcting. Reflex I guess from years of flying RC pattern, helis, etc.

You know it is going to hook, so anticipate just a tiny bit and use the sticks to keep it going where you want it to go. Maybe not the solution you want, but that thing in your hands actually can control the Phantom's motion!

Ideally DJI will get this addressed, but in the interim flying it instead of pointing it will help. I messed around a bunch the last couple of days and found that if I was moving slowly and stopping gradually this was barely noticeable. Since that is the way I normally fly combined with my unconscious correction on the sticks made it so I did not really notice this. But, if I haul @$$ at near full tilt and just let go of the sticks it will hook left, but not more than a few feet for me.

 

[ianwood]

A thought occurs to me that it appears people want this thing to basically fly itself. I think one reason this did not get noticed by me as much as some others is that I was more or less automatically correcting. Reflex I guess from years of flying RC pattern, helis, etc.

You know it is going to hook, so anticipate just a tiny bit and use the sticks to keep it going where you want it to go. Maybe not the solution you want, but that thing in your hands actually can control the Phantom's motion!

Ideally DJI will get this addressed, but in the interim flying it instead of pointing it will help.

Thanks for the brilliantly obvious advice. I'm sure everyone would just keep pointing it and slamming into trees and walls until they read your post and realize they should fly it instead.

 

[SilentAV8R]

Thanks for the brilliantly obvious advice. I'm sure everyone would just keep pointing it and slamming into trees and walls until they read your post and realize they should fly it instead.

Thank you. I did audition for the part of Captain Obvious on the Hotels.com commercials, but I got beat out.

 

[gorano]

i did finde this on this forum it is exat what i experien i have a declaration of 10

 

[PCDan]

For what its worth, I have a the new P2, I updated everything last night to most current firmware with the assistant software. I flew last night with no wind. It seemed to fly very straight with very little drift/hook at the end of a straight run. Seems more stable hovering as well, but that could have been the total lack of wind. I am in Park City UT with 12 degrees E declination. I will fly again today and take a video if its not windy.

 

[Andy T]

I suppose people just want what the thing is supposed to deliver. If the company said all the GPS is for is to bring it home safely then your argument would be valid but they promise it will fly itself.. A lot of people including myself wouldn't buy a machine like this if it wasn't extremely easy to fly.

A thought occurs to me that it appears people want this thing to basically fly itself. I think one reason this did not get noticed by me as much as some others is that I was more or less automatically correcting. Reflex I guess from years of flying RC pattern, helis, etc.

You know it is going to hook, so anticipate just a tiny bit and use the sticks to keep it going where you want it to go. Maybe not the solution you want, but that thing in your hands actually can control the Phantom's motion!

Ideally DJI will get this addressed, but in the interim flying it instead of pointing it will help. I messed around a bunch the last couple of days and found that if I was moving slowly and stopping gradually this was barely noticeable. Since that is the way I normally fly combined with my unconscious correction on the sticks made it so I did not really notice this. But, if I haul @$$ at near full tilt and just let go of the sticks it will hook left, but not more than a few feet for me.

 

[SilentAV8R]

I suppose people just want what the thing is supposed to deliver. If the company said all the GPS is for is to bring it home safely then your argument would be valid but they promise it will fly itself.. A lot of people including myself wouldn't buy a machine like this if it wasn't extremely easy to fly.

I get what you are saying, but a part of me thinks perhaps we are expecting too much from these things. They are consumer grade devices. They are not professional level equipment. For what they are, they are amazing. THe ease of flying allows you to focus on what they are intended to do, which is obtain aerial images (video/still). But even there, the camera is good, but far from professional level.

I work with surveyors who use GPS location equipment that blows away my Garmin. It also costs 2 orders of magnitude more than my little Garmin. So for me, I see some of this as just the limits of how well a relatively low cost system can be expected to perform. Add to that the fact that the "limits" can be minimized by doing just a little active piloting.

It is great that DJI seems to want to improve their product, but I wonder if they will be able to overcome the inherent limitations of the device itself. So is this really a "defect" or is it just the best the system can produce??