[ros-users] Oddness in global plan from navfn / costmap_2d

Armin Hornung HornungA at informatik.uni-freiburg.de
Fri Apr 16 10:13:43 UTC 2010

Hi Eitan!

> Thanks so much for finding this, I've fixed the bug in both trunk (rev
> 28749) and the 1.0 branch (rev 28750) of navigation and the fixes will go
> out with the next patch release of both the 1.0 and the 1.1 series. I'll try
> to push out patch releases either later today or tomorrow and I believe it
> should fix the problem you're seeing.

I had a look at the fixed navfn now, and the paths indeed look a lot 
nicer and smoother now. Thanks!

Now only the strange behavior at the start and the end of a path remain, 
as seen in the attached screenshot. It seems like the computed path 
starts and ends at the top right grid cell center of the actual start 
and goal position, with an added (unsmooth) path segment from the 
computed goal to the requested one. The effect is of course more 
pronounced in larger grid resolutions (and also happend in my empty test 
case map). Is that something fixable in the navfn code?

If it's only possible to plan on grid cell centers, a workaround could 
be to start and end the computed path on the grid cell that is between 
the actual (requested) goal and start and then adding a first and last 
segment which extends the computed path in a similar direction. That 
should cause a less discontinuous curve.


Armin Hornung                              Albert-Ludwigs-Universität
www.informatik.uni-freiburg.de/~hornunga   Dept. of Computer Science
HornungA at informatik.uni-freiburg.de        Humanoid Robots Lab
Tel.: +49 (0)761-203-8010                  Georges-Köhler-Allee 79
Fax : +49 (0)761-203-8007                  D-79110 Freiburg, Germany

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