ROS2

Node, Topic

$ ros2 run <package_name> <node_name> # run a node

e.g.:

$ ros2 run turtlesim turtlesim_node

$ ros2 run turtlesim turtle_teleop_key

$ ros2 node list # list all the running nodes

$ ros2 node info <node_name> # check the info of a node

publisher & subscriber -- for communication

$ rqt_graph # visualize the relationship between publishers and subscribers

$ ros2 topic list # list all the running topics

$ ros2 topic info <topic_name> #check the info of a topic

$ ros2 topic echo <topic_name> # display the data being published on this topic right now

$ ros2 topic hz <topic_name> # how many messages being published on this topic per second

Workspace, Package

Create an ROS workspace:

$ mkdir -p my_ws/src

~ my_ws/src $ git clone <repository>

~/my_ws $ colcon build

~/my_ws $ source install/

Create an ROS package

~/my_ws $ ros2 pkg create --build-type ament_<programming_language> <package_name>