[ros-users] Nav Stack with nonholonomic robots

Eitan Marder-Eppstein eitan at willowgarage.com
Tue Sep 7 05:15:30 UTC 2010


Christian,

First off, its true that navigation is not fully "solved" for real world
environments. We're trying to provide a system that improves the navigation
capabilities of a large number of robots, but there's still a lot of work to
be done. We do try to test the navigation stack as often as possible on our
PR2, and have had mostly positive results, but that doesn't necessarily mean
it will work well in all cases. As far as the problems you're having, I'd be
curious to see the launch files that you're using to bring up the navigation
stack on your robot. I've looked at those parameters a lot, and might be
able to give some insight into what's going on.

I'd also be curious to see if you experience the same problems with the
navigation stack in simulation. If you can create launch files that show a
simulated version of your robot having the problems you described, it would
allow us to reproduce the behavior your seeing and give us a better shot at
fixing things. We could even add these tough cases as tests for the
navigation stack so that others with diff-drive robots don't have to
experience the pain you've been through. If you want, you can check out the
navigation_stage package for a template of how to run navigation in a
simulated environment.

I'm sorry that it hasn't been a pleasant experience so far, but hopefully
we'll figure out what's going on.

Are other diff-drive folks experiencing these kinds of problems with their
setups?

Hope all is well,

Eitan

On Mon, Sep 6, 2010 at 10:27 AM, Brian Gerkey <gerkey at willowgarage.com>wrote:

> On Sat, Sep 4, 2010 at 12:12 AM, Christian Verbeek
> <verbeek at servicerobotics.eu> wrote:
> >  I am using move_base for driving a robot with non holonomic drive. I
> > found the performance to be poor to wholly unacceptable. I played around
> > with the parameters for quite a time and was not able to find a
> > satisfactory setting. The problem with the parameters is that I most of
> > the time I can not see a difference at all when changing something.
> >
> > My impression is that the navigation stack works in tidy and roomy
> > environments. But in real world settings with narrow passages and stuff
> > standing around performance drops dramatically. I tried this both woth
> > boxturtle and latest cturtle and can not see any improvements. The
> > navigation (which is in my eyes the most basic behaviour) is so to say
> > still unsolved for real world environments.
>
> hi Christian,
>
> Hmm, that's a less than glowing assessment of the navigation stack.
> I'd be interested to find out exactly what's going wrong.  We use the
> navigation stack all the time on the PR2 in our office, which is
> neither tidy nor roomy.  It frequently avoids many small obstacles,
> and squeezes through tight openings.  Of course, the PR2 is an
> omni-drive robot, and we test less often on differential-drive robots.
>  But the navigation stack is intended to support differential-drive
> robots, and there's no reason that it shouldn't work well in that
> situation.
>
> Can someone who's had more success with the navigation stack on
> differential-drive robots suggest a good set of parameters?
>
>        brian.
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