Navigation Stack does not use a map from Gmapping?

Question

In navigation stack, the tutorial is based on a static map and amcl for localization. When using with slam, some people suggested just exclude the static map and amcl and run gmapping.

I already did that and it worked. However, when I looked into rxgraph, why the only topic move_base(Navigation stack) use from Gmapping is /tf and it does not use /map from Gmapping at all?

I've looked into the code and guessed it might create map by itself in costmap2D from laser scan in move_base node.

If this is true, would it be better to use the real map from Gmapping?

Only costmap from laser scan and correct position from Gmapping through /tf is enough correct?

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Originally posted by ParNurZeal on ROS Answers with karma: 91 on 2012-01-02

Post score: 0

Answer 1

Just to clarify. The costmap_2d is capable of taking updates to the static map from a SLAM system such as gmapping. Any time a new map comes in over the /map topic, the static map used by the navigation stack is re-initialized. Are you sure that the global costmap of the navigation stack is configured to subscribe to this map? If so, you should be seeing the move_base node as subscribed to the /map topic.

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Originally posted by eitan with karma: 2743 on 2012-01-05

This answer was ACCEPTED on the original site

Post score: 4

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Original comments

Comment by ParNurZeal on 2012-01-13:
http://answers.ros.org/question/1583/whats-the-difference-between-global-and-local <-- I read your answer in this topics as well. Thank you for clarification!

Comment by ParNurZeal on 2012-01-13:
Now, I understand. Like what you said it's true. I set the global cost map not to receive static map but use rolling windows. http://answers.ros.org/question/399/navigation-stack-with-gmapping <-- this made me misunderstand.

Comment by ParNurZeal on 2012-01-09:
I see. I think I need to check it whether I set the global costmap of the navigation stack to subscribe to the map or not. Because I did not see the move_base node subscribed any /map topic. Will tell again whether this is the problem or not. Thank you very much for guiding :)

Comment by ctguell on 2014-03-10:
@ParNurZeal hi im having your same problem, when i look in the rxgraph i se a tf topic and not a map going in the move_base. Is this correct? Any help would be really appreciated @Eric Perko

Answer 2

move_base never subscribes directly to a map. It uses the Costmap2D to handle mapping.

If you look at the costmap_2d docs, you'll see that it does subscribe to /map if your have configured it to initialize with a static map. Note that the map is only read for initialization and will be overwritten if a sensor such as a laser marks those cells as clear (assuming you have a clearing sensor feeding into the costmap that was initialized from a static map).

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Originally posted by Eric Perko with karma: 8406 on 2012-01-03

This answer was NOT ACCEPTED on the original site

Post score: 2