Re: [Paparazzi-devel] AR.Drone 2 magnetometer issues?

[Ori Pessach]

OK, here's the problem I'm trying to fix:

https://www.flickr.com/photos/address@hidden/16420497916/

The drone was in the patio, sitting parallel to the house. In the screenshot, it's pretty obviously rotated counterclockwise. The magnetometer isn't rotated in the drone, I calibrated it (several times, in fact) and I entered what I believe is the correct local magnetic field into the airframe file. 

This is an intermittent problem. Sometimes I'll boot up the drone and it'll point in the right direction for a while, but then it'll decided to rotate like this. Sometimes I can't get it to point in the right direction at all. When the drone's orientation in the telemetry is correct, it seems to take off and fly fine for a while. When the orientation is wrong, it will (predictably) do stupid things and try hard to crash itself. :)

Any ideas would be greatly appreciated. I find this extremely baffling.

Thanks!

Ori

On Sat, Jan 31, 2015 at 9:17 AM, Gautier Hattenberger <address@hidden> wrote:

Just to be clear, if the mag is dead, the values are completely fixed. In this case, it looks ok.
Now you can have a look at the scaled values, the mag should be beween -1 and 1.

Gautier

Le 31/01/2015 01:50, Ori Pessach a écrit :

Just how much variability should I expect between MAG readings? A dump of IMU_MAG_RAW messages from a recent log taken with the drone resting on a table looks like this:

349.004 201 IMU_MAG_RAW 73 79 23

349.102 201 IMU_MAG_RAW 73 83 19

349.151 201 IMU_MAG_RAW 75 73 21

349.200 201 IMU_MAG_RAW 71 85 17

349.249 201 IMU_MAG_RAW 72 84 24

349.298 201 IMU_MAG_RAW 74 84 22

349.346 201 IMU_MAG_RAW 69 83 23

349.444 201 IMU_MAG_RAW 71 79 17

349.492 201 IMU_MAG_RAW 72 80 20

349.542 201 IMU_MAG_RAW 71 81 21

349.639 201 IMU_MAG_RAW 71 83 21

349.688 201 IMU_MAG_RAW 71 81 21

349.737 201 IMU_MAG_RAW 75 79 25

349.834 201 IMU_MAG_RAW 75 75 23

349.882 201 IMU_MAG_RAW 71 75 25

349.933 201 IMU_MAG_RAW 77 81 27

349.985 201 IMU_MAG_RAW 70 82 22

350.029 201 IMU_MAG_RAW 75 81 25

350.128 201 IMU_MAG_RAW 68 76 24

350.225 201 IMU_MAG_RAW 74 76 22

350.274 201 IMU_MAG_RAW 72 82 22

350.322 201 IMU_MAG_RAW 71 83 21

350.373 201 IMU_MAG_RAW 72 80 20

350.468 201 IMU_MAG_RAW 74 76 24

350.517 201 IMU_MAG_RAW 73 79 15

350.568 201 IMU_MAG_RAW 74 78 18

350.615 201 IMU_MAG_RAW 71 81 19

350.664 201 IMU_MAG_RAW 75 81 21

350.713 201 IMU_MAG_RAW 70 82 16

350.762 201 IMU_MAG_RAW 73 85 27

350.810 201 IMU_MAG_RAW 68 76 22

350.862 201 IMU_MAG_RAW 75 79 25

350.908 201 IMU_MAG_RAW 70 80 24

350.956 201 IMU_MAG_RAW 70 82 24

I have no idea whether this should be considered normal...

On Fri, Jan 30, 2015 at 3:08 PM, Ori Pessach <address@hidden> wrote:

I'm using 5.4, I'm not sure about the filter, and I've seen mag values that appear very wrong (the drone is rotated on the map) even immediately after I boot the drone. I'll have to check the logs from the last couple of times I took the drone out to know about the raw values.

I'm considering just trying to attach a 3rd party magnetometer to the drone using an arduino, or something like that, and patching paparazzi in order to get something working...

On Fri, Jan 30, 2015 at 2:53 PM, Gautier Hattenberger <address@hidden> wrote:

From my experience, ARDrone2 mag are really crappy, and they can fail at any time.
If you run a recent version (v5.4 or master), you *should* have a IMU_LOST indicator in the GCS strip when it occurs (in place of the GPS status).
We have tried to implement something to restart the navboard, but it is very difficult to test since the crashes are unpredictable. It has run for hours on my desk without issues, same for TUDelft guys, but maybe it is still not perfect.
What is your paparazzi version ? which filter are you using ? are the raw mag values still changing when it starts to go wrong ?

Gautier

Le 30/01/2015 22:29, Ori Pessach a écrit :

So, any ideas from anybody? I'm considering getting a new nav board, but they're not terribly cheap so I thought I'd try to figure out whether the one I have is broken, or whether they're all like that.

Thanks,

Ori

On Sun, Jan 25, 2015 at 7:14 PM, Ori Pessach <address@hidden> wrote:

Hi,

I was wondering if someone who had some experience flying the AR.Drone 2 could tell me whether what I'm seeing is typical, or a sign of a possible hardware issue.

The magnetometer readings seem to be very erratic. I've seen a range of behaviors:

* Tracking the drone's direction perfectly.

* Showing a direction that's rotated 180 degrees

* Showing a direction that's rotated 90 degrees counterclockwise (???)

* Being JUST a little bit off, and then appearing to be perfectly fine after I took the drone and walked around in circles while holding it. 

So, what's going on? I've been seeing some serious navigation issues, and I'm wondering if the magnetometer can get out of calibration midflight, which might explain the erratic behavior I've been seeing: Taking off perfectly, holding position fine, and then navigating to the first waypoint and staying there without issues. Things after that can be pretty erratic, however, including going way off course on the way to the next waypoint, wobbling wildly back and forth, and sometimes trying to fly into the ground at high speed at a 45 degree angle. Which fails, because of immutable physical properties the ground happens to possess. 

I've calibrated the magnetometer, changed the values for the local magnetic field, and the fact that SOME things work, at least at first, would indicate that the drone should be able to fly fine - at least as far as I understand it. 

So... What now? 

Ori

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