Gazebo Simulation¶

Run robot demos with Gazebo Harmonic physics simulation.

Prerequisites¶

Workspace built
Gazebo Harmonic packages installed

Install Gazebo¶

sudo apt install ros-jazzy-gz-*

Steps¶

1. Source Workspace¶

From the workspace root after ./init_repo.sh and colcon build:

source install/setup.bash

2. Launch with Gazebo¶

hardware:=gz sets xacro ros2_control_hardware_type to gz and gazebo to true (build_xacro_mappings()). ocs2_arm README: install ros-jazzy-ros-gz and ros-jazzy-gz-ros2-control.

ros2 launch ocs2_arm_controller demo.launch.py hardware:=gz

Acone xacro plugin for this key: gz_ros2_control/GazeboSimSystem. gz is a launch key, not a vendor hardware-interface package — Hardware Interfaces.

3. Interact¶

FSM: /fsm_command (std_msgs/Int32). Do not publish /target_pose. See FSM and Topics.

Launch Options¶

# Acone (dual-arm, not Lift 2S)
ros2 launch ocs2_arm_controller demo.launch.py robot:=arx_acone hardware:=gz

demo.launch.py declares world (default dart). It does not declare rviz:=false or headless:=true.

Gazebo Features¶

Physics Tuning¶

The default physics parameters work for most robots. For custom tuning, modify the SDF files in the description packages.

World Files¶

demo.launch.py declares world (default dart). Use only world keys that exist in the description / launch you are running.

Recording¶

Record simulation for playback:

gz service -s /world/default/control \
  --reqtype gz.msgs.WorldControl \
  --reptype gz.msgs.Boolean \
  --timeout 3000 \
  --req 'pause: false'

Mock vs Gazebo¶

Aspect	Mock	Gazebo
Physics	None	Full simulation
Speed	Real-time	Configurable
Collisions	No	Yes
Sensors	Placeholder	Simulated
Resource use	Low	Medium-high

Use mock for controller development, Gazebo for behavior testing.

Verification¶

Gazebo window shows robot in environment
Robot responds to ROS 2 commands
Physics interactions (collisions, gravity) work

Troubleshooting¶

Gazebo crashes on start¶

# Check GPU drivers
nvidia-smi

# Try software rendering
export LIBGL_ALWAYS_SOFTWARE=1
ros2 launch ocs2_arm_controller demo.launch.py hardware:=gz

Robot falls through floor¶

Check that the world file includes a ground plane.

Controllers don’t start¶

Wait for Gazebo to fully initialize before sending commands. Check for error messages about failed controller spawning.

High CPU usage¶

Reduce physics update rate or run headless:

See the Gazebo / ros-jazzy-ros-gz docs for renderer settings. This launch file does not document a headless:= argument.