Do you have these debugging skills?
Some of which you only learn with experience!
Debugging in robotics is different.
You are not just dealing with code.
You are dealing with ‘real time’.
With sensors that could lie.
With messages that often never arrive.
With logs that say "all good", while your robot silently crashes into a wall.
And if you are early in your journey, this can feel overwhelming.
Consider today’s issue like a field guide to the real-world debugging skills every robotics software engineer needs, but rarely gets taught.
Do not Start in the Code; Start in the System:
When something breaks, your instinct is to open the code.
Pause. Zoom out.
Check:
Are all nodes running? (
ros2 node list)Is data flowing? (
ros2 topic echo,rqt_graph)Are you sourcing the right workspace?
Did the robot even launch properly?
Most bugs are not in your logic. They are in the way components connect (or do not).
Know Your Tools Like a Surgeon:
You are only as good as your introspection tools.
Memorise:
ros2 topic echo /topic_nameros2 service callros2 action list,ros2 action send_goalros2 node inforqt_graph,rqt_console,rqt_plottf2_echo,tf2_monitor,view_frames
Callbacks, Deadlocks, and Other Silent Obstructions:
If your node freezes, it is probably not your algorithm, it is your threading.
ROS2 is fundamentally asynchronous.
Timers, subscribers, services, and actions all operate in parallel.
Calling a service synchronously inside a subscriber callback, with a single-threaded executor.
Result? Deadlock.
Your callback waits for the service response, but the service response can’t be processed because… the executor is still stuck waiting on the callback.
Use a MultiThreadedExecutor or separate callback groups to handle long or blocking operations.
And if you see random hangs, incomplete logs, or a node that "sometimes" dies, suspect concurrency first.
Use --ros-args --log-level debug and add heartbeat logs in each callback.
Log Like a Detective:
Good logs win you the case.
Don't just print. Use:
self.get_logger().info("Subscribed to image topic")
Bonus:
Use
--ros-args --log-level DEBUGduring launchUse
rqt_consoleto filter and trace issues across nodesAdd logs at boundaries: when you receive, process, and publish
Debugging = storytelling.
Respect Time (It is Trying to Trick You):
Timestamps matter. A lot.
Your SLAM stack, your controllers, and your transforms all rely on consistent timing.
Watch out for:
Nodes not using
use_sim_timein the simulationSensors publishing old or zero timestamps
Transforms arriving late → extrapolation errors
Time bugs are sneaky. But once you understand them, you will see them everywhere.
Assume the Sensor is Lying:
Before blaming your algorithm, check the data.
Does your IMU jitter when standing still?
Is odometry drifting?
Does your LiDAR scan match reality?
Are you sure you're reading the right frame?
ros2 topic echo, rqt_plot, and visual overlays in RViz are your best friends.
Simulation Bugs are Still Bugs:
Do not dismiss them.
Just because “it is not real hardware” does not mean the bug is not real.
Gazebo bugs often expose:
Race conditions
TF misconfigurations
Topic mismatches
Unstable control gains
Frame issues
Run everything in Docker or with reproducible launch files. And use ros2 bag record liberally.
If it is Asynchronous, it will Fail Differently:
Race conditions. Deadlocks. Missed callbacks.
In robotics, everything runs in parallel:
Sensor streams
Timers
Service requests
Actions
Watch out for:
Blocking service calls in callbacks
Nodes freezing under single-threaded executors
Data races from shared state
Rule: Test under load, not just ideal conditions.
Reproduce First, Fix Later:
You cannot fix what you can’t repeat.
Before changing code:
Try to reproduce the bug at least twice
Record with
ros2 bagStrip your launch down to the smallest setup that breaks
Get Comfortable Being Uncomfortable:
This one is hard to teach.
But it is everything.
Robotics is messy.
Your code might be fine. But the battery died.
Or the bag file is corrupt.
Or the launch sequence was off by 2 seconds.
The best engineers?
They do not panic. They investigate.
Systematically. Calmly.
Debugging is not a skill you “learn.”
It is a skill you build.
The more you see, the more you will spot patterns.
The more you build, the faster you will trace failures.
Keep building. Keep breaking. Keep learning.
Resources to start building today:
🌟 Open Source Robotics Projects on GitHub
📚 GitHub Repositories to Learn Robotics
🛠️ ROS Resources
🚀 ROS 2 Resources
🎥 YouTube Channels & Playlists to Learn Robotics
🏫 Free University Courses
📖 Books to Learn Robotics
🎮 Robotic Simulators
FREE access here - getintorobotics.com
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