[Example 13] Multi-robot system with lifecycle management

[christophfroehlich]

This is a rewrite of #187 including StoglRobotics-forks#7.

Open questions for me:

• The problems discussed in the latter PR are summarized in Ressource manager hangs up on lifecycle changes ros2_control#1103. I'd say we can add this example even if the problem is not fixed yet.
• It uses the rrbot URDF from example_4 and example_5. Should I generate new ones inside example 15? Currently, there is also the FTS broadcaster etc in Rviz, but maybe this wouldn't be necessary and we could just use the same Rrbot instead. -> we decided in the WG meeting to reuse descriptions for the multi-robot examples.
• Why should one use a global joint state broadcaster? In the original version it was not configured properly, and all "individual" JSB published on the /joint_states topic and it seemed to work (better than now, without the necessity of reloading the JSB). The only difference is that with the global one, all joints are within one message. Why would someone need this for multiple robots?

[christophfroehlich]

@Mergifyio backport iron humble

[mergify]

backport iron humble

🟠 Waiting for conditions to match

• merged [📌 backport requirement]

[saikishor]

With the 7th point, I don't get the same result. For me all the robots stopped moving and the following is the output from list_controllers command

$ ros2 control list_controllers
rrbot_joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] inactive  
threedofbot_pid_gain_controller[forward_command_controller/ForwardCommandController] active    
threedofbot_joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] active    
rrbot_with_sensor_joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] active    
joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] inactive  
rrbot_with_sensor_fts_broadcaster[force_torque_sensor_broadcaster/ForceTorqueSensorBroadcaster] active    
rrbot_with_sensor_position_controller[forward_command_controller/ForwardCommandController] active    
rrbot_position_controller[forward_command_controller/ForwardCommandController] inactive  
rrbot_external_fts_broadcaster[force_torque_sensor_broadcaster/ForceTorqueSensorBroadcaster] active    
threedofbot_position_controller[forward_command_controller/ForwardCommandController] active

[christophfroehlich]

That's true. The joint_state_broadcaster cannot be activated again (the cli returns a success, but it is not activated).
Because of the verbose output described with ros-controls/ros2_control#1103 I was not able to see any error message from the controller_manager. Neither in rqt_console or rqt_robot_monitor I see any error message.

[saikishor]

Thanks for getting back. If I get some time, I will try to take a look at this issue.
Thank you for reporting it

[christophfroehlich]

This seems to be fixed in the meantime?

[mergify]

This pull request is in conflict. Could you fix it @christophfroehlich?

[mergify]

This pull request is in conflict. Could you fix it @christophfroehlich?