[ros-users] base_local_planner and ackerman kinematics?

[Eitan Marder-Eppstein]

Domenico,

The base_local_planner is just the default plugin that can be used with the
navigation stack as a local planner.... just as navfn is the default plugin
for the global planner for the navigation stack.

The base_local_planner does not have any settings that allow it to handle
ackerman kinematics, but you could write another plugin that would, see
http://www.ros.org/wiki/nav_core for a description of plugin interfaces, and
still be able to use the rest of the navigation stack.

To my knowledge, no one has used the navigation stack with an autonomous
car, but that doesn't mean that it can't be done. I'd imagine that it will
at least need new plugins for both the global and local planners, as well as
a lot of parameter tweaking, to get working.

Perhaps the U.T. Austin folks will chime in with their experiences running
ROS on their car.

Hope this helps,

Eitan

On Tue, Sep 21, 2010 at 9:48 AM, Domenico G. Sorrenti <
sorrenti at disco.unimib.it> wrote:

> Dear all,
>
> we are trying to use ros for an autonomous driving project, i.e., involving
> a car-like vehicle.
>
> We passed through the documentation that we have been able to find in the
> web (i.e., the list of ros packages), and we could not find an alternative
> to base_local_planner. BTW, given the size of the list and ourselves being
> 1st-time users, we would really appreciate a confirmation about this
> inference being correct.
>
> The work most related to ours that we could find is the Marvin Darpa Urban
> Challenge autonomous car (U.Texas at Austin, P. Stone lab.), which is
> reported having been ported to ROS. In the art_vehicle stack we could find
> the art_nav package and the pilot node, which looked to us as the one that
> might be including the solution to the problem. We might have mis-understood
> the description of its working, but it appears to us as a node accepting ros
> commands, not issuing them.
>
> Assuming base_local_planner to be a required package (beside a global
> planner), we thought we need to have it to avoid issuing "rotation in place"
> commands. In other words, as the vehicle cannot rotate in place, we thought
> we should inhibit base_local_planner to consider rotation in place as an
> admissible motion primitive, during planning.
>
> Unfortunately, we have not been able to devise a way to push
> base_local_planner to disregard such rotations.
>
> We apologize if we missed relevant online documentation about our question.
>
> Do you have some suggestion about how to force base_local_planner not to
> use rotation in place or, in general, on how to deal with ackerman
> kinematics in ros?
>
> Thanks for your attention. All the best. Domenico, Axel, Andrea, Francesco.
>
> --
> Domenico Giorgio Sorrenti, Ph.D.
> Dipartimento di Informatica, Sistemistica e Comunicazione,
> Universita` degli Studi di Milano - Bicocca,
> Building U14, viale Sarca 336, 20126, Milano, Italy
> tel +39 026448.7841, fax +39 026448.7805
> email <mailto:sorrenti at disco.unimib.it>sorrenti at disco.unimib.it, <
> http://www.disco.unimib.it/sorrenti>http://www.disco.unimib.it/sorrenti
> _______________________________________________
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