[ros-users] Navigation stack not working

[Eitan Marder-Eppstein]

Eric,

On Mon, Sep 20, 2010 at 11:19 AM, Eric Perko <wisesage5001 at gmail.com> wrote:

> 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...
>

Did you set the unknown_cost_value parameter? (
http://www.ros.org/wiki/costmap_2d#Map_management_parameters). If this is
set, and your costmap is tracking unknown space, you should be able to get
the costmap to load unknown cells from the static map. If that's not the
case, then its a bug in the costmap that I need to track down. Leaving the
unknown_cost_value parameter at zero does default to unknown cells being set
to occupied in the costmap, so its possible that's what was happening to
you.

Let me know how it goes,

Eitan


>
> - 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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