Troubleshooting
What you might see while setting up or starting the robot container, how to check the cause, and how to fix it. The commands run on the Raspberry Pi, in ~/diffbot/.docker/robot, unless the row says on the PC.
| What you see | Check | Fix |
|---|---|---|
| SSH can't connect | The router lists the Raspberry Pi. The first boot takes a few minutes | Wait. If it never appears, check the Wi-Fi name and password in Imager and write the card again |
docker commands fail with permission denied for docker.sock |
groups lists docker |
Log out and in again after usermod |
| Compose stops with bind source path does not exist | ls -ld ~/robot-data |
mkdir -p ~/robot-data, or set ROBOT_DATA |
Compose stops with error gathering device information for /dev/teensy or /dev/rplidar |
ls -l /dev/teensy /dev/rplidar, lsusb |
Plug the device in, install the udev rules (step 7). Without a lidar, remove COMPOSE_PROFILES=lidar |
A setting in .env has no effect |
docker compose config --environment shows the value that Compose uses |
A variable with the same name in the shell wins over .env: remove its export, for example from ~/.bashrc, log in again, then docker compose up -d (When Compose reads .env) |
The bringup's output shows Permission denied for /dev/ttyACM0 |
stat -Lc %g /dev/teensy |
Write that number into DIALOUT_GID |
The bringup stops with cannot create log directory and Permission denied for /home/ros/.ros/log |
ls -ldn ~/robot-data ~/robot-data/log: UID 1000 must be able to write, for example owner 1000 with drwx |
sudo chown -R 1000:1000 ~/robot-data, then sudo chmod -R u+rwX ~/robot-data |
| The bringup or the lidar stops with unable to contact ROS master | roscore runs on the PC. ping the PC's address from the Raspberry Pi |
Start roscore first, then docker compose up -d. Correct ROS_MASTER_URI. A PC with WSL 2 needs mirrored networking |
The PC lists the robot's topics, but rostopic hz shows no messages |
ROS_IP on each machine is its own address |
Correct ROS_IP on the robot or the PC. Both directions must work (ROS Network Setup) |
| The bringup's output shows Unable to sync with device | The Teensy has the firmware, the USB cable carries data | Flash the firmware (Microcontroller) |
No /diffbot/scan |
docker compose ps -a lists lidar as running |
Set COMPOSE_PROFILES=lidar, then docker compose up -d. If it exited, its output in docker compose logs lidar tells why |
The lidar still runs after removing COMPOSE_PROFILES=lidar |
docker compose ps -a |
docker compose --profile lidar down, then docker compose up -d |
After changing .env, run docker compose up -d again: Compose recreates the containers whose settings changed. To switch the lidar off, run docker compose down first, while COMPOSE_PROFILES=lidar is still set.
Logs explains where to find the robot's messages.
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