Introduction to Gazebo and ROS Integration

Importance of Simulation in Robotics

• Simulations are crucial in robotics development.
  • Avoids expense, time consumption, and danger of testing on real hardware.
• A good simulation environment can be valuable.

Gazebo: Free Robotic Simulation Environment

• Created by Open Robotics, same group behind ROS.
• Gazebo and ROS are managed separately but integrate well together.
• Creation of a virtual world and loading of simulated robots.

Key Features of Gazebo

• Simulated sensors detect the environment and publish data to ROS topics.
• Simulated actuators and physics (e.g., friction) are incorporated.
• Rewritten and replaced with Ignition Gazebo (Ignition).
  • Compatibility issues with certain plugins currently.
  • Tutorials will use Gazebo Classic for now.

Getting Started with Gazebo

• Installation: sudo apt install ros-foxy-gazebo-ros-packages
• Running Gazebo without ROS: gazebo [path to world file]
• Example: Loading the built-in seesaw world.

Navigating Gazebo Interface

• Controls: Left click to pan, middle click to orbit, right click/scroll to zoom.
• Inspecting models in the world (e.g., ground plane, cubes, fulcrum, plank).
• Interaction with models, applying forces, resetting world state.

Integrating Gazebo with ROS

• Gazebo Model Structure: Uses SDF (Simulation Description Format).
• Gazebo plugin system for interacting with ROS.
• Example: Using ros2 launch and ros2 run to integrate URDF with Gazebo.
• Converting URDF to SDF for simulation.

Setting Up the Robot State Publisher with Gazebo

• Importance of publishing joint states.
• Simulating joint movements and feeding them back to ROS.
• Example Plugins: gazebo_ros_joint_state_publisher, gazebo_ros_control_plugin

Controlling Robots within Gazebo

• Simulating sensors, e.g., cameras.
• Creating custom environments in Gazebo editor.
• Example: Using the model editor for walls or objects like construction barrels.
• Saving and loading custom worlds.

Sensor Simulation: Camera and Depth Camera

• Adding and simulating camera sensors.
• Gazebo ROS Camera Plugin for regular camera.
• Gazebo ROS Depth Camera for generating point cloud data.

Challenges and Practical Tips

• Setting use_sim_time parameter for all ROS nodes in simulation.
• Understanding Gazebo's architecture:
  • Server and client processes.
  • Debugging tips: killing processes if they crash (killall gzserver gzclient).

Conclusion

• End of tutorial series on simulating robots with Gazebo and ROS.
• Upcoming series on building an autonomous mobile robot.
• Encourage engagement and subscription for further tutorials.