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PhysiCar ROS 2

examples/physicar-ros.ipynb is a runnable tour of the robot's two programming interfaces: its ROS 2 topics and its local Web API. Every sensor gets read, every control gets published, every endpoint gets called — one cell at a time. The other examples are wrappers around what this notebook shows; run it first and none of them will look like magic.

Inside the notebook

Section What you run
1. ROS 2 Interfaces rclpy setup, then every sensor topic — camera, battery, IMU, odometry, LiDAR — and every control topic: /cmd_vel, /speed, /steering, camera pan/tilt
2. Web API the same robot over HTTP: sensor queries (with streaming), control — including duration driving and the WebSocket dead-man switch — and audio playback

Run it

  1. In the workspace file explorer, open examples/physicar-ros.ipynb.
  2. Pick the Python 3 (PhysiCar AI) kernel when asked.
  3. Run the setup cell of a section first; after that, jump to whatever interests you.

It runs the same in the simulator and on a real kit — that is the point: the topics and endpoints are identical, so this notebook is the Sim2Real contract.

Worth noticing

  • wait_for_message — receive one message without spinning a node; the pattern that makes ROS 2 pleasant in a notebook.
  • Sensor QoS — the LiDAR publishes best-effort; subscribe with qos_profile_sensor_data or you receive nothing.
  • The watchdog — a plain /speed command expires after about a second. A robot that stops hearing from you is a robot that stops.
  • POST /speed with duration — the server holds the speed, stops at the end, and only then answers. One request, one complete and safe maneuver.
  • Units — speed in m/s; /steering in radians, ±0.35 (≈±20°); camera pan/tilt ±30°.
  • Audio — POST /audio/play takes a URL, a file path, or raw base64; in the simulator the sound plays in the browser viewer.

🛠 Mission: using only Web API calls, drive a (rounded) square: four POST /speed requests with duration, a POST /steering between each.

Learn more

Topics and nodes, gently → ROS2 basics. Full topic list → ROS2 interface reference. Full endpoint list → Web API.

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