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Re: [Paparazzi-devel] Using Waypoints in GPS/absolute coordinates (Maste

From: Felix Ruess
Subject: Re: [Paparazzi-devel] Using Waypoints in GPS/absolute coordinates (Master branch)
Date: Wed, 5 Jun 2013 00:01:35 +0200


just committed a change to master which sets USE_INS_NAV_INIT to TRUE by default.
To explicitly disable it add <define name="USE_INS_NAV_INIT" value="FALSE"/> to your firmware section.

Cheers, Felix

On Sun, May 12, 2013 at 4:55 PM, Gautier Hattenberger <address@hidden> wrote:

I did the nav init a long time ago and using flight plans was still experimental at that time.
If the flag is not set, the ins init will be done as soon as the the GPS gets a 3D fix, so the behavior is the same than NavSetGroundReferenceHere.
It is not the default because at that time we wanted to have local flights if nothing was set. Maybe it is not true anymore.


Le 12/05/2013 13:20, Loic Drumettaz a écrit :
Hi Felix,

It does help, thanks!

So I see 2 user cases:
1: Relative coordinates: call NavSetGroundReferenceHere during geo init in the flight plan and the flight plan origin is defined instead of lat0 and lon0 in the flight plan .xml file. In that case it's preferable to define the waypoints in relative coordinates. If absolute coordinates are used, the waypoints position will be wrong after geo init...

2: Absolute coordinates: set USE_INS_NAV_INIT to "TRUE" in airframe configuration xml file. The flight plan origin is defined by lat0 and lon0 coordinates in the flight plan. In that case it's preferable to define the waypoints in absolute coordinates. If relative coordinates are used to define the waypoints, that's OK, the only thing is that the origin of the flight plan is defined at lat0 and long0.

What happens if USE_INS_NAV_INIT is left to FALSE and the origin is not initialized using NavSetGroudReferenceHere? Is that case meaningfull?

Why not set USE_INS_NAV_INIT to TRUE by default? The user can then still call NavSetGroundReferenceHere in the flight plan to reset the origin of the flight plan if he wants?



Hi Loic,

absolute coordinates are currently not really handled in a nice way, improvements welcome.

What you can do is to add <define name="USE_INS_NAV_INIT" value=TRUE"/>
This will initialize the ground reference (origin of the LTP) with the flight plan coordinates, instead of leaving it uninitialized (to be set from the GPS fix with NavSetGroundReferenceHere).
You still need to remove NavSetGroundReferenceHere from your geo init though, as that would just reset it to the current position.

If you still want your home waypoint to be automatically set to where you start, in geo init: <call fun="NavSetWaypointHere(WP_HOME)"/>

Hope that helps...
Cheers, Felix

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