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Im using navigation with gmapping and wanted to know that if in the global_costmap_params.yaml the static map should be true or false? I have it with false and its working fine. the problem is that when i look in rxgraph the move_base node DOES NOT subscibe to the /map but to /tf published by gmapping. Can anyone explai to me why is it that /map message does not appear in rxgraph?
You definitely should be running the costmap with a static global map for gmapping. If you're using a laser scanner for global navigation, you will get artifacts and potentially false openings/obstacles whenever gmapping decides to relocalize itself.
Depending on your ros distribution (i.e. hydro and layered costmaps), you can also subscribe to updates on the /map topic, which would make it work properly with gmapping.
@paulbovbel when i put the static global map true the navigation does not work and i get the following error. You have set map parameters, but also requested to use the static map. Your parameters will be overwritten by those given by the map server. So i dont know what to do, also the /tf message that goes from gmapping to move_base what does it send? @demmeln
move_base will need transforms from your robot frame to your costmaps' global frames. That's usually odom for local, and map for global.
Even though you set a width, height and resolution for your costmap, those will be overwritten by the map received from gmapping, so you can probably leave those blank.
@paulbovbel thanks, when you say theres a tf from map to global whats its use?? to use map as the globalcostmap?? thanks
EDIT: Apparently this has changed, see first comment.
I'm not quite sure, but from the documentation ( http://wiki.ros.org/costmap_2d#Subscr... ) it seems that with a static map, the costmap is initialized only once at the beginning by making a service call to the the map server. It does not contiuesly update from a "map" topic. I'm not sure if an updateing gridmap can be achieved with the current implementation or if you have to write a custom layer for the global costmap.
move_base node DOES NOT subscibe to the /map but to /tf published by gmapping
This is normal, I guess, since the costmap is created using the laser detections (or whatever source of mesures about obstacles you are using) and it is updated according to what these sensors are seeing in real time. (cause if not you won't be avoiding moving obstacles like people and chairs moved so often for example)
/map is only used for localisation (whether by launching GMapping which does it while building the map OR by loading some previously built map and using amcl), and sending goals intuitively in rviz using the right tool..
Asked: 2014-04-03 19:10:59 -0500
Seen: 1,635 times
Last updated: Dec 15 '15
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@demmeln when i look in the rxgraph i only see the move_base node related to navigation i dont see the any costmap, but it appears that the costmap subscribes to the /map. So why is there no costmap node and is the /map only usefull for localisation as @AbuIbra ? i have to explain whats the use of /map