Run the ROS2 Turtlesim Node to spawn the turtle

ros2 run turtlesim turtlesim_node

in a new terminal, run the tele-operation key node

ros2 run turtlesim turtle_teleop_key

Alright, now as these nodes from the turtlesim pkg are up-and-running, let us take a deeper look into it.

Then, we can fetch the information of any node using

ros2 node info /turtlesim

Similarly, we can fetch the information of other nodes

ros2 node info /teleop_turtle

Here, we have subscribers and publishers, and their message type. Notice that, the subscriber turtle1/cmd_vel in the node info of /turtlesim node is the publisher in the node info of /teleop_turtle node. As we have seen, the turtle in the TurtleSim window gets the data from the teleop node, and it is through THIS (cmd_vel) topic.

Vector3 is a type of message, which includes x, y and z component, which are all of type float64. The Twist type of message, utilized this Vector3 type of message to take inputs and produce outputs.

So, if you want to add a new publisher/subscriber to the topic /turtle1/cmd_vel, we will send, first, a Vector3 for linear velocity, then a Vector3 for angular velocity.