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Connecting Kobuki Robot via USB on Ubuntu

When connecting the Kobuki base to Ubuntu through USB (e.g., /dev/ttyUSB0), you may encounter a permission error when launching the ROS/robot control node.

Temporary Fix (Every Time)​

You can temporarily give all users read & write permissions to the USB device with:

sudo chmod 666 /dev/ttyUSB0
  • 666 means read & write for everyone.
  • However, this setting only lasts until the device is disconnected.
  • Reason: /dev/ttyUSB0 is a dynamically created device file managed by udev.
    When you unplug and replug the robot, the old file is destroyed and a new one is created, which resets its permissions.

⚠️ This means you have to run chmod 666 every time you reconnect the robot, which is very inconvenient.

A better solution is to add your user to the dialout group, which already has access to serial devices by default.

Run this command once:

sudo usermod -aG dialout $USER

Then log out and log back in (or reboot).
After that, you can access /dev/ttyUSB0 without running chmod again.

✅ Summary:

  • chmod 666 works but is temporary and insecure.
  • Adding your user to the dialout group is the permanent and secure solution.