car

ROS 2 Car Control Demo (Electron + rclnodejs)

Interactive car-control app: a virtual joystick publishes geometry_msgs/Twist velocity commands on /cmd_vel, and a visualization subscribes and moves a car in real time.

Features

• Joystick plus WASD / arrow-key control with an emergency stop
• Real-time car movement, position tracking, and command counter
• ROS 2 node car_control_node publishing and subscribing on cmd_vel

Prerequisites

• ROS 2 (Humble, Jazzy, Kilted, Lyrical, or Rolling), sourced
• Node.js >= 20.20.2
• Linux (prebuilt rclnodejs binaries are provided for Ubuntu)

Install & Run

cd demo/electron/car
source /opt/ros/<distro>/setup.bash   # required before install and launch
npm install
npm start

rclnodejs ships prebuilt Electron binaries and selects the matching one at runtime from ROS_DISTRO + Linux codename + architecture, so no compilation is needed. Do not run electron-rebuild against rclnodejs — it rebuilds from source and bypasses the prebuilt binary (the Forge rebuildConfig in package.json already excludes rclnodejs).

Controls

• Mouse: directional buttons (↑ ↓ ← →) and the red STOP button
• Keyboard: W/S forward/back, A/D turn, Space or Esc to stop

Message Format & Mapping

geometry_msgs/Twist on /cmd_vel:

Command	linear.x	angular.z
Forward	+1.0	0.0
Backward	-1.0	0.0
Left	0.0	+1.0
Right	0.0	-1.0
Stop	0.0	0.0

Test from the CLI

ros2 topic echo /cmd_vel
ros2 topic pub /cmd_vel geometry_msgs/Twist "{linear: {x: 1.0}, angular: {z: 0.0}}"

Packaging

npm run package   # standalone app in out/
npm run make      # zip / deb / rpm installers (needs zip, dpkg, fakeroot)

ASAR is enabled but rclnodejs is unpacked (asar.unpack in package.json) because it needs filesystem access to its generated code and native bindings. The target machine must still have ROS 2 installed and sourced — rclnodejs links dynamically to ROS 2 shared libraries:

source /opt/ros/<distro>/setup.bash
./out/rclnodejs-electron-car-demo-linux-x64/rclnodejs-electron-car-demo

Troubleshooting

• "Failed to initialize ROS2" — source ROS 2 before npm start.
• Native module fails to load — ensure ROS_DISTRO is set so the prebuilt binary matches; as a last resort set RCLNODEJS_FORCE_BUILD=1 (needs a compiler toolchain and network access).
• Topic missing — check ros2 daemon status and ros2 topic list.
• Car not moving — open the DevTools console and check for errors.

License

Apache License 2.0, same as rclnodejs.