[ros-users] Navigation stack not working

[Eric Perko]

Eitan,

On Mon, Sep 20, 2010 at 1:49 PM, Eitan Marder-Eppstein <
eitan at willowgarage.com> wrote:

> Prasad,
>
> Sorry for joining the discussion a bit late.
>
> A couple of things:
>
> 1) The voxel grid tracks unknown space, but its not published in the
> visualization of the grid. It was just too many cells to render. If you want
> to see the 2D projection of unknown space in the voxel grid, you can
> subscribe to the unknown_space topic of the relevant costmap.
>

Is this true even if the information comes from the static map? I'm 99% sure
we saw all of the unknown space in the static map be reported on the
/obstacles topic as an obstacle; even after playing around with some of the
parameters for the voxel grid that had to do with unknown space, we still
had that problem. This was using a map that came from GMapping and the
OccupancyGrid from map_server seemed to have plenty of -1's in it (so it did
have the proper thresholds). Needless to say, seeing the majority of a
4000x4000 map all reported as obstacle is a bit intensive...

- Eric


>
>

> 2) Publishing visualization information from very large maps can slow the
> system down. As Eric suggested, setting publish_frequency to 0 for the
> global_costmap should help things.
>
> 3) Changing the update_frequency from 5.0Hz to 8.0Hz actually makes the map
> update more frequently so I'm not sure why this resolved anything for you.
>


4) For large maps, on some machines, I can see it taking some time for AMCL
> to start up. Do the errors your experiencing go away consistently after AMCL
> is successfully up and running?
>
> Hope all is well,
>
> Eitan
>
> On Mon, Sep 20, 2010 at 4:07 AM, Prasad Dixit <abhimohpra at gmail.com>wrote:
>
>>
>> Hello Eric,
>> I have changed the update rate from 5.0 to 8.0.
>> Though It is taking lot of time initially to load the map and configuring
>> likehood model; it worked finally..
>> Is it something because i have not specified position in AMCL? Is this
>> taking lot of time to spread initial particles and get exact global
>> position
>> of robot in the map?
>> OR is it completely related to hardware which i should update it
>> finally...??
>> - Prasad
>> --
>> View this message in context:
>> http://ros-users.122217.n3.nabble.com/Navigation-stack-not-working-tp1519053p1528384.html
>> Sent from the ROS-Users mailing list archive at Nabble.com.
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>
>
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