Goncalo,

There are a few basic things that you can do to help with performance:

1) You can increase the resolution of the costmaps. Since a Roomba is so
small, even 10cm resolution should probably be sufficient for navigation.
See the resolution parameter of the costmap:
http://www.ros.org/wiki/costmap_2d#Map_management_parameters

2) You can decrease the update rate of the costmaps from 5Hz to something
lower depending on your tolerance for seeing an obstacle. At 5Hz, it'll take
about 1/5th of a second to react to an obstacle, at 3Hz 1/3rd of a second,
etc. See the update_frequency parameter for the costmap:
http://www.ros.org/wiki/costmap_2d#Rate_parameters.

3) You can control the Roomba at a lower rate... maybe something like 10Hz
instead of 20Hz. For that you can set the controller_frequency parameter on
move_base: http://www.ros.org/wiki/move_base#Parameters.

Hope this helps,

Eitan

2010/7/7 Gonçalo Cabrita <goncabrita@gmail.com>

> Hi everyone!
>
> Here at the lab we use Roomba robots with Eee PCs on top. The Eee PCs have
> a single core Intel Atom processor, not the quickest thing around! Each
> Roomba is also equiped with an Hokuyo laser.
>
> So I've recently been playing around with the ROS nav stack. I've tried to
> make it as simple as possible according to the various tutorials and mailing
> list msgs I've came across with, however I'm always getting a warning that
> it is running below the 20Hz frequency. It is also noticeable the fact that
> the robot does not move properly, and eventually crashes.
>
> Previously I experimented the same setup on an Erratic robot with a
> Celeron, and although it was taking pretty much all of the processor to run
> the nav stack, it was able to move pretty well around the lab according to
> the commands I was issuing from rviz.
>
> So my question is, how can I use the nav stack in its simplest form, in
> order to have it running smoothly on the Eee PCs?
>
> I'm attaching the .yaml files I'm using for configuring the nav stack.
>
> Thanks in advance!
>
> Gonçalo Cabrita
>
>
>
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