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A1: Watchdogs and Health Monitoring

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

Learning Objectives​

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

  • Implement watchdog timer patterns for node monitoring
  • Create heartbeat mechanisms for health reporting
  • Build health status aggregation systems
  • Detect and respond to node failures
  • Integrate with ROS 2 diagnostics framework

Introduction​

Production robotic systems require robust health monitoring to detect failures before they become critical. This lesson teaches you how to implement watchdog patterns and health monitoring systems that ensure your workflows operate reliably in real-world conditions.

Coming Soon​

This lesson is currently under development. In the meantime:

  1. Review Prerequisites: Ensure you completed the Intermediate tier and understand multi-node workflows

  2. Practice with Exercises: Complete Exercise 01: Watchdog System Implementation which provides detailed implementation guidance with starter code

  3. Explore AI Prompts: Use Advanced AI Prompts for watchdog and monitoring help

  4. Study Patterns: Review the watchdog pattern in the Chapter Summary

Planned Topics​

This lesson will cover:

1. Watchdog Fundamentals​

  • What is a watchdog and why it's essential
  • Watchdog timer patterns
  • Timeout detection strategies
  • False alarm prevention

2. Heartbeat Mechanisms​

  • Implementing heartbeat publishing
  • Heartbeat message design
  • Frequency and timing considerations
  • Network latency handling

3. Health Status Monitoring​

  • Health status message structures
  • Aggregating health from multiple nodes
  • Health state machines
  • Diagnostic message publishing

4. Failure Detection​

  • Detecting node crashes
  • Detecting communication failures
  • Detecting performance degradation
  • Timeout calculation strategies

5. ROS 2 Diagnostics Integration​

  • Using the diagnostics framework
  • Diagnostic aggregator
  • Publishing diagnostic messages
  • Monitoring tools and visualization

6. Production Patterns​

  • Multi-level monitoring (node, system, fleet)
  • Alerting strategies
  • Log correlation
  • Performance metrics

Resources​

While this lesson is in development, use these resources:

Next Steps​

Continue to A2: Supervisor Nodes and Recovery or practice with Advanced Exercises