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Hochschule für Informatik FHNW P9 — Mars Rover Autonomy

Demo · live · read-only

A virtual rover, driven by n8n

A self-contained showcase for the ROS 2 node package: a simulated rover that offers real ROS 2 topics, services and actions, eleven n8n workflows that drive it, and a read-only live view on the public web. Everything the workflows do shows up on screen.

How it fits together

The robot is turtlesim wrapped in a rover-shaped interface: a battery that drains while driving, a dock that recharges it, an e-stop, and a map with landmarks drawn on it so a demo can talk about places rather than coordinates. n8n reaches it over a rosbridge WebSocket on the internal Docker network.

Two things are worth pointing at. The custom message types are discovered at runtime — rover_interfaces is a real ROS 2 interface package with nested messages, and nothing about them is hardcoded in n8n. And every interface documents itself: each one publishes a latched <name>/desc topic saying what it is for, which is how an agent that has never seen this robot can still work out what to call.

Three choices keep it safe to leave on the internet: rosbridge is bound to localhost and never exposed, the live view is read-only at the protocol level rather than by convention, and the workflows that only observe use a credential that is refused at the node level if it tries to publish or call a service. 

                  ┌─ n8n editor      (owner login)
Internet ─ Caddy ─┤
    (TLS)         └─ live view       (read-only, public)

internal network
  n8n ──ws──▶ ros2 container
                ├─ rosbridge + rosapi   (not exposed)
                ├─ turtlesim on Xvfb
                ├─ x11vnc -viewonly ─▶ noVNC
                ├─ rover_node.py
                └─ camera_node.py

What the robot exposes

Actions

  • /rover/navigate_to Drives to one point. Feedback carries distance remaining; cancellable.
  • /rover/patrol Visits named waypoints in order, feedback per waypoint, optional looping.

Services

  • /rover/set_led Sets the status LED, which is also the trail colour.
  • /rover/dock Drives home and starts charging. Preempts a running mission.
  • /rover/emergency_stop Engages or releases the e-stop.
  • /rover/reset_demo Full reset: battery, e-stop, trail, back to the centre.

Topics

  • /rover/status Rover state at 2 Hz. Embeds the battery and the current waypoint.
  • /rover/battery Charge and charging state at 1 Hz.
  • /rover/events One JSON message per event — this is what the watchdog triggers on.
  • /rover/camera/compressed The screen, published as a camera topic at 2 Hz.

Embedded live view, the status readout, the workflow gallery and the agent chat land here as the demo hosts come online. Until then the cards above open each one directly.