[ros-users] Wifi communication getting slow

[William Woodall]

I setup a little robot using a roomba and a hokuyo lrf to do the gmapping
slam, I did not use amcl at all.  You can examine my launch files and config
files on github to see what I did.

https://github.com/wjwwood/sparcexplorer/blob/master/stacks/sparcexplorer/sparcexplorer_launch/launch/exploration.launch

If I wanted to have gmapping run on my laptop (if say the robot's computer
was too slow) I would just comment it out of the exploration launch file and
run it manually on my laptop instead.

I am also using Bosch's exploration node so the robot drives itself around
exploring the area. (http://www.ros.org/wiki/exploration)

When I was first experimenting with the nav stack I got the same turning in
place behavior, it was because the point you selected as a goal is off the
map, which is probably the case because you have the map misconfigured or
something similar.  I think if you get your move_base setup working
correctly you'll find this behavior might away.

Hope that helps,

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Woodall
Graduate Software Engineering
Auburn University
w at auburn.edu
wjwwood at gmail.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


On Wed, Jan 5, 2011 at 10:37 AM, Steven Bellens <
steven.bellens at mech.kuleuven.be> wrote:

> Hey,
>
> 2011/1/4 Dan Lazewatsky <dlaz at cse.wustl.edu>:
> > Hi Steven -
> > I've noticed similar problems on a few of our robots, mainly when using
> > image_transport to send video over wifi. To figure out if wifi is the
> > problem, there are two things I've found helpful: before starting any of
> the
> > code running, from your workstation, ping the robot and see if the ping
> time
> > increases. The other thing you can try is watching iwconfig on the robot
> to
> > see if the link quality deteriorates over time.
> > Unfortunately, I never really figured out what was going on. Replacing
> the
> > wifi cards in the affected computers seemed to solve the problem.
> > -Dan
>
> I've figured out the problem occurs the moment I start running the
> navigation stack. I've been able to build a map using gmapping
> (running the gmapping mode on the groundstation), and the ping
> responses were constantly okay. When I start up navigation without a
> pre-build map (amcl - move base - gmapping), the ping responses
> suddenly increase (from 2 - 8 ms to 1000+ ms). When I try the same
> with a static map, everything goes well. Am I doing something wrong in
> this setup, e.g. can I run amcl and gmapping at the same time? If not,
> how should I run the navigation stack without a prebuild map?
>
> Another problem I face is about the navigation: the holonomic robot
> localizes itself OK, but the goals I send with rviz only manage to let
> it rotate (there is never a translational velocity command), so the
> robot starts rotating, but never gets anywhere close where I want him
> to go :). Any ideas on that?
>
> regards,
>
> Steven
>
> regards,
>
> Steven
>
> >
> > On Tue, Jan 4, 2011 at 9:15 AM, Steven Bellens
> > <steven.bellens at mech.kuleuven.be> wrote:
> >>
> >> Hi,
> >>
> >> when using ROS to command a mobile base, I'm running a hokuyo_node and
> >> an orocos component node on the mobile base. On my workstation I have
> >> the navigation stack running, which gets laserscan data from the
> >> hokuyo node and sends velocity commands to the orocos component. I
> >> only switched to use the wireless network recently and noticed that,
> >> after running the app for some minutes, it looks like some delay
> >> starts to build up: when I drive the robot with the teleop_keyboard,
> >> after 2 minutes, it starts reacting very slow on my input commands.
> >> What's the best way to determine if the Wifi is indeed the problem
> >> and, if so, can I run this more optimally with ROS considering this
> >> restriction?
> >>
> >> regards,
> >>
> >> Steven
> >> _______________________________________________
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> >
> >
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