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I2: Multi-Node Pipelines with Launch Files

Status: Content in development. See Intermediate Exercises for hands-on practice with this topic.

Learning Objectives​

By the end of this lesson, you will be able to:

  • Create Python launch files for multi-node systems
  • Configure node parameters in launch files
  • Implement topic remapping for flexible connections
  • Use launch arguments for conditional node launching
  • Debug and troubleshoot launch file issues

Introduction​

Launch files are essential for orchestrating complex multi-node workflows. This lesson teaches you how to use ROS 2's launch system to start, configure, and coordinate multiple nodes as a cohesive system.

Coming Soon​

This lesson is currently under development. In the meantime:

  1. Review Prerequisites: Ensure you completed I1: State Machines in ROS 2

  2. Practice with Exercises: Complete Exercise 02: Sensor Processing Pipeline and Exercise 03: Multi-Node Launch File

  3. Explore AI Prompts: Use Intermediate AI Prompts for launch file help

  4. Study Official Docs: Review ROS 2 launch system documentation

Planned Topics​

This lesson will cover:

1. Launch File Basics​

  • Python launch file structure
  • LaunchDescription and Node actions
  • Basic node configuration
  • Running launch files

2. Parameter Configuration​

  • Declaring parameters in launch files
  • Loading parameters from YAML files
  • Parameter substitutions
  • Dynamic parameter configuration

3. Topic Remapping​

  • Why and when to remap topics
  • Remapping syntax in launch files
  • Namespace management
  • Best practices for topic naming

4. Advanced Launch Features​

  • Launch arguments and substitutions
  • Conditional node launching
  • Event handlers
  • Composable nodes

5. Multi-Node Orchestration​

  • Starting multiple nodes
  • Node dependencies and ordering
  • Launch file composition
  • Debugging multi-node systems

Resources​

While this lesson is in development, use these resources:

Next Steps​

Continue to I3: Inter-Node Communication or practice with Intermediate Exercises