Basic Info

Description of contribution in a few bullet points

This changes make it more convinient to manage nav2_params.yaml file for multi-robot environment and easy to launch the navigation.

According to latest guideline, each robot requires different nav2_param files since absoulte path of topic ifor scan is required in local_costmap/global_costmap node.

if we set the topic name without slash'/' like 'scan', rclpp node will add prefix automatically for example , local_costmap/local_costmap/scan. So we should specify absoulute path such as /scan or /namespace/scan

But, the code I suggested will rewrite the value for the key 'topic:'.
As far as I know, 'topic' key is only used for costmap plugins

I think this changes quite make sense. :)

Description of documentation updates required from your changes

For multi-robot launch, it should be launched with namespace leading prefix '/'.

ros2 launch nav2_bringup bringup_launch.py  map:=install/cloi_external_config/share/cloi_external_config/map/seocho_tower_B1F_0.yaml use_namespace:=True namespace:=/acloi00

This shall try to subscribe local_costmap/local_costmap/acloi00/scan.

ros2 launch nav2_bringup bringup_launch.py  map:=install/cloi_external_config/share/cloi_external_config/map/seocho_tower_B1F_0.yaml use_namespace:=True namespace:=acloi00

So the guideline for mutli-robot bringup should be noticed.

Future work that may be required in bullet points

First time when I faced this inconvenient environemnt, I'd like to describe the 'param_rewirtes' like this.

{'local_costmap.local_costmap.ros__parameters.*.*.topic': (namespace,'/scan')}

I tried to modify RewrittenYaml() class what I thougt and expected but gave up :) because I''m not familiar with this class.

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists