[ros-users] navigation stack bare minimums

[Eric Perko]

Mike,

You can also set all costmaps to rolling windows with their global
frame as /odom. As long as you actually publish a tf between that and
base_link (or whatever you want to call your equivalent frames), you
should be able to run completely without a map server. I can
definitely say that it is possible to run navigation without a static
map - I am currently doing just that and have had no issues related to
lack of map server.

As far as required transforms goes, you really ought to be publishing
transforms for the different frames. You could use the
static_transform_publisher node to publish a static transform, but the
transform from base_link to odom is not static, so you will need to
broadcast that transform yourself.Another option is to use one of the
existing simulators (stage and gazebo) that hook into ROS, which
broadcast all the transforms you should need.

Hope that helps.

- Eric

On Thu, Jun 3, 2010 at 8:32 PM, William Woodall <wjwwood at gmail.com> wrote:
> Mike, while the tutorial for setting up the navigation stack says that you
> can just set the static_map: yaml setting to false if you don't have a map
> server, I have found it easier to just setup a map server and give it a
> small white image, basically just a blank map.
> I would recommend following these tutorials:
> Navigation (Including the tf setup)
> Map Server (While this isn't a tutorial, you can use the example
> configurations)
> Hope that helps,
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> William Woodall
> Graduate Software Engineering
> Auburn University
> w at auburn.edu
> wjwwood at gmail.com
> 256-345-9938
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> On Thu, Jun 3, 2010 at 5:07 PM, Mike Purvis <mpurvis at clearpathrobotics.com>
> wrote:
>>
>> I have a few questions about setting up the navigation stack. I have a
>> very simple simulator node which broadcasts Odometry messages and consumes
>> Twist messages. Using a GUI program, I've been able to monitor and verify
>> the performance of this node.
>> Assuming that for the purposes of getting started, I don't (yet) care
>> about mapping or obstacle-avoidance, is this simulation enough to run the
>> navigation stack?
>> I've followed the tutorials as best I can, but of course I haven't got a
>> map, so map_server fails to start, and then move_base gives this warning:
>> [ WARN] 1275592139.432109000: Waiting on transform from base_link to /map
>> to become available before running costmap, tf error: Frame id /base_link
>> does not exist!
>> This is expected, as I have not broadcasted any tf transforms. But my
>> robot has no joints or geometric parts, so there's nothing to broadcast---as
>> far as the simulator is concerned, it's just a box on wheels. Is there a way
>> to make the base_link frame exist independent of using
>> a tf::TransformBroadcaster to broadcast its relationship to another frame?
>> Further to that, how do I address the larger map issue? Can I disable the
>> mapping functionality somehow (for now), or should I just create a blank map
>> and let it use that?
>> Is my objective completely unreasonable, or is this just a matter of some
>> configuration tweaks?
>> Thanks in advance for any suggestions or guidance,
>> Mike
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>
>
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