02. Overview

In this lesson, you’ll be learning how to write nodes in Python.

The first node that you will be writing is called simple_mover . simple_mover does nothing more than publish joint angle commands to simple_arm .

After you've developed a basic understanding of the general structure of a ROS Node written in Python, you will be writing another node called arm_mover . arm_mover provides a service called safe_move , which allows the arm to be moved to any position within its workspace which has been deemed to be “safe”. The safe zone is bounded by minimum and maximum joint angles, and is configurable via the ROS’ parameter server.

The last node you’ll write in this lesson is the look_away node. This node subscribes to a topic where camera data is being published. When the camera detects an image with uniform color, meaning it’s looking at the sky, the node will call the safe_move service to move the arm to a new position.