RE: [Paparazzi-devel] Course desired issues

[Roman Krashanitsa]

I would check is there is any angle conversion for desired course and actual course right at the point where telemetry is sent. It may be in ap_downlink.h or in the place where the message is sent.

 

I think that since your airplane is following trajectory, the navigation part and gps part are fine. All bad things happen during the communication.

 

Hope this helps.

 

Roman

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From: address@hidden [mailto:address@hidden On Behalf Of Haiyang Chao
Sent: Friday, June 13, 2008 12:31 AM
To: address@hidden
Subject: Re: [Paparazzi-devel] Course desired issues

Just a few details to add for this question. Any comment is welcomed.

In nav.c, line 309,  desired course is calculated as:  h_ctl_course_setpoint = M_PI/2.-atan2(y - estimator_y, x - estimator_x);
The function atan2() can return values between [-pi, pi]. So the desired course is just between [-pi/2,pi*3/2].

But for GPS course, based on my observation, moving north is roughly 0 or 2*pi, moving south is around pi, moving east is pi/2, moving west is pi*3/2.

So I guess there must be some difference between real course and desired one unless there are some limitations on estimator_x and estimator_y, which I have not take a detail look in the code. Really busy recently for some hardware problems.

Thanks
Haiyang

On Thu, Jun 12, 2008 at 10:57 PM, Daniel Morgan <address@hidden> wrote:

I have been talking to poine and anton about this issue for a couple of days and they both concluded it should not be happening... What is happening on this plot is the course desired's range is -90 to 270 and and the acutal is 0 to 360... Now i talked to anton today and he said that he talked to poine and they thought it was a issue with my code being messed up or something.. So on his advice i changed my old paparazzi's folder name and did a completely new cvs... When i did this it did not aleviate the issues. So i thought maybe it was something with my pc or my config, because of this i decided to try out a completely clean system. What i did was i booted of a ubunut 8.04 live cd and installed pprz from this last nights tarball(cvs command was having issues for some reason)and used only the files in the cvs and still got the same issue. The screenshot is from that (you may notice the time is off but don't let that fool ya)... Needless to say i am hoping someone who knows the code better can fix this or at least shed some more light on it...

here is that screenshot
http://img127.imageshack.us/img127/1593/screenshot1vh4.png

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