qdilmac / ros2_udemy

My ROS2 Udemy course files

ROS2 Udemy Course Files

Edouard Renard's (Robotics Back-end) Udemy course that I took about ROS2

Small notes that i took along the course

• We can modify the topic name of publisher/subscriber on runtime

  • ros2 run py_pkg_example smartphone --ros-args -r robot_news:=new_topic_name
  • ros2 run py_pkg_example robot_news_station --ros-args -r robot_news:=new_topic_name

• We can also do the same for nodes

  • ros2 run py_pkg_example robot_news_station --ros-args -r __node:=new_node_name

• Can do these both at the same time too

  • ros2 run cpp_pkg_example robot_news_station --ros-args -r __node:=new_node_name -r robot_news:=new_topic_name

-> an example for node/topic name remapping

• ros2 interface show example_interfaces/{msg, srv etc.}/{msg, service, ... etc.'s name}

  • This line gives us a brief explanation about data type of service, message etc. Quite useful

• ros2 run py_pkg_example sum_server

• ros2 service call /sum_service example_interfaces/srv/AddTwoInts "{a: 3, b: 5}"

  • For the services we create the server node, then with self.create_service we create a server for it
  • To use the service in the server we first run the server then we call the service with appropiate service name and give it the inputs that it gets.