ROS 2 Lyrical Luth · Lesson 83 of 86

Building a warehouse simulation

Project: a warehouse world with shelves, aisles, docks and moving obstacles.

Estimated time · 120–180 min

Learning goals

What you will understand

Explain building a warehouse simulation in your own words
Use it in a small robotics example
Verify the result instead of assuming it worked

Understand the idea first

The mental model

A warehouse simulation combines the world (walls, aisles, shelves, pallets, a charging dock), one or more robots and any moving obstacles such as people or forklifts. Write it as a world SDF with parameterized model poses and a launch file that starts Gazebo, spawns the robots and bridges the topics.

Make it repeatable: fixed random seeds, the same starting poses, and scripted scenarios (deliver a pallet, cross a busy aisle) so you can compare software versions. Log every run to a bag and compute metrics: success rate, time per task, collisions, near misses and recoveries.

Guided lesson

Work through these steps

1.
Source the ROS 2 Lyrical environment in a fresh terminal.
2.
Read the building a warehouse simulation example and identify what each line does.
3.
Build only the affected package, source the workspace overlay, and run the example.
4.
Inspect the result from a second terminal with the ros2 CLI or RViz2 and compare it with the expected result.

Worked example

Read it before you run it

worlds/warehouse.sdf
# The world: 30 × 20 m, four aisles, twelve shelves, one charging dock.
launch/sim.launch.py
# Starts Gazebo with the world and the ROS bridges.
scenarios/deliver_pallet.yaml
# Scripted task: pick point, drop point, time limit.
ros2 launch warehouse_sim sim.launch.py world:=warehouse.sdf robots:=2
# Start the world with two robots.
ros2 bag record -o run_001 /odom /scan /tf /goal_status
# Record a run for later analysis.

What the example is doing

1.The ros2 commands query the running graph; they do not prove that a node's internal behavior is correct.
2.Build from the workspace root, then source install/setup.bash so the shell can discover the new package.
3.Use a second sourced terminal to inspect nodes and interfaces while the example runs.

Watch it run · Mobile robot

See what this code does

The terminal types this lesson's practice solution and runs it. The scene shows the kind of robot behaviour that code drives. It plays by itself and loops.

Practice code

Now type it yourself

Copy the starter into your ROS 2 package, replace every TODO, then build with colcon build and run it from a sourced terminal.

# launch/sim.launch.py
from launch import LaunchDescription
from launch.actions import ExecuteProcess


def generate_launch_description():
    # TODO: start Gazebo with the world file worlds/warehouse.sdf, running immediately (-r)
    return LaunchDescription([gz])

Expected output

The world starts with 12 shelves

Stuck? Show the full solution (try it yourself first)

# launch/sim.launch.py
from launch import LaunchDescription
from launch.actions import ExecuteProcess


def generate_launch_description():
    gz = ExecuteProcess(cmd=['gz', 'sim', '-r', 'worlds/warehouse.sdf'], output='screen')
    return LaunchDescription([gz])

Expected result

How you know it worked

ROS_DISTRO is lyrical in every terminal used for the exercise.
The complete package from the exercise builds and the expected graph entity appears in a second terminal.

Practical exercise

Apply the lesson

Build the warehouse world with twelve shelves and one dock, run a scripted scenario ten times, record bags, and report success rate, average time and number of recoveries.

Before you continue

ROS_DISTRO reports lyrical in every terminal you used
The example builds and runs without errors
You checked the result with a ros2 command, RViz2 or a test, not just by reading the code

If something goes wrong

ros2 cannot find a package or executable.

Source /opt/ros/lyrical/setup.bash, build from the workspace root, then source install/setup.bash in that terminal.

Nodes run but cannot discover each other.

Confirm both terminals use Lyrical, the same ROS_DOMAIN_ID, and compatible network/discovery settings.