Feature request

Feature description

We'd like to be able to support multiple robots navigating simultaneously on the same system in simulation -- no coordination at this moment, more on that coming soon 😃

For this we need to:

• If simulation, have Gazebo launch multiple robots (on a single instance) and facilitate launching multiple nav stacks for different robots. [multirobot - Part 1] Spawn multiple robots into Gazebo #1146, [multirobot - Part3] Add multi-robot launching #1148
• Logical partitioning using namespaces for partitioning (grouping services, actions, etc. from a single robot) as a first approach. [multirobot - Part2] Add namespacing to nav stack #1147
• Visualize robots in RVIZ and use plugins to provide initial and goal poses to each robot. [multirobot - Part4] Multiple robot control via RVIZ #1149

Implementation considerations

For partitioning, we have a few options:

• Logical
  • Namespaces
  • DDS Keyed Data (not exposed by ROS2)
  • DDS Domain and Participants (not sure if exposed by ROS2)
• Physical

Most users in ROS1 used separate namespaces for different robots (together with a multi-master pkg). We can replicate that as a starting point, however, there are several reasons we might want an alternative approach, i.e. DDS discovery, Robot encapsulation, etc.