Start the robot simulation and Navigation2

Understand the simulation stack

The running robot uses two components:

• rox_simu loads the Neobotix ROX model into Gazebo, simulates its sensors and motors, and publishes laser scan, camera, and odometry data
• rox_nav2 runs Navigation2 for localization, path planning, and velocity control

The simulation and navigation stack run as separate processes so you can start, stop, and observe each component independently.

Stop the talker and listener from the router experiment. Keep the router running.

Open two new terminals in the robot container and source the environment in each one:

    

        
        
source ~/workshop_env.bash

    

Start the headless simulation

In one of the new Terminals, start the simulation:

    

        
        
just rox_simu no_gui

    

The no_gui argument disables the Gazebo 3D viewer, not the simulation. Gazebo continues to simulate the robot and publish sensor data while using less CPU.

Start Navigation2

In the other Terminal, start the navigation stack:

    

        
        
just rox_nav2

    

Wait for Navigation2 to activate its managed nodes.

It is normal for output to stop after its active. Navigation2 remains idle until it receives a navigation goal.

Verify the simulated sensors

In another sourced terminal, check the laser scan frequency:

    

        
        
ros2 topic hz /scan

    

The /scan topic should arrive at approximately 8 Hz. This rate is an expected operating observation, so small variations are normal.

List the camera topics using a new terminal:

    

        
        
ros2 topic list | grep camera

    

The output should include /camera/image_raw, /camera/points, and /camera/depth/image_raw.

What you’ve accomplished and what’s next

You’ve started the headless Gazebo simulation, activated Navigation2, and verified that laser and camera sensor data is available. Next, you’ll use RViz to inspect the navigation data and send the robot a goal.