Skip to main content

Chapter 3: Python Integration with rclpy

Controlling Robots with Python Code

From Robot Description to Robot Control

Chapter Overview​

In Chapter 2, you learned to describe robot structure using URDF—defining links, joints, masses, and geometry.

In Chapter 3, you'll take the next step: controlling those robots using Python code.

This is where robotics comes alive. Instead of just describing what a robot looks like, you'll write Python programs that:

  • ✅ Send velocity commands to make robots move
  • ✅ Read and modify configuration parameters
  • ✅ Implement goal-reaching behaviors with progress feedback
  • ✅ Coordinate multiple robots and sensors

What You'll Learn​

Three Key Topics​

Section 1: rclpy Basics (8 minutes)

  • Understand Python node structure
  • Create publishers for velocity commands
  • Implement control loops that send repeated commands

Section 2: Working with Parameters (7 minutes)

  • Declare parameters (configuration values)
  • Read parameters in code
  • React to parameter changes without restarting

Section 3: Actions for Goal-Reaching (8 minutes)

  • Understand when to use actions (vs topics/services)
  • Implement action servers (execute goals)
  • Send goals from action clients

Prerequisites​

Before starting this chapter, ensure you've completed:

  • Chapter 1: ROS 2 Basics (nodes, topics, services)
  • Chapter 2: URDF Robot Description (links, joints, visualization)
  • Basic Python programming skills

Chapter Status: Ready for Learning ✅ Last Updated: 2025-11-30 Estimated Time: 35-40 minutes reading + 25-35 minutes practice