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Weeks 6-7: Robot Simulation with Gazebo

Learning Objectives​

During these two weeks, students will learn to create and work with robot simulations using Gazebo, the standard simulation environment for ROS-based robotics.

Topics Covered​

  • Gazebo simulation environment setup

    • Installing and configuring Gazebo
    • Understanding the physics engine
    • Creating and managing simulation worlds

  • URDF and SDF robot description formats

    • Unified Robot Description Format (URDF)
    • Simulation Description Format (SDF)
    • Converting between formats and their use cases

  • Physics simulation and sensor simulation

    • Modeling physical properties: mass, inertia, friction
    • Simulating various sensor types
    • Configuring physics parameters for realism

  • Introduction to Unity for robot visualization

    • Unity as an alternative simulation environment
    • High-fidelity rendering capabilities
    • Human-robot interaction studies

Key Concepts​

Gazebo Physics Simulation​

Gazebo provides a realistic physics simulation environment using the ODE (Open Dynamics Engine), Bullet, or DART physics engines. Key features include:

  • Rigid body dynamics: Accurate simulation of physical interactions
  • Sensor simulation: Cameras, LiDAR, IMUs, force/torque sensors
  • Contact simulation: Collision detection and response
  • Realistic rendering: Visual simulation with lighting and materials

URDF (Unified Robot Description Format)​

URDF is an XML format for representing a robot model. It describes:

  • Kinematic structure: Joint and link relationships
  • Visual properties: How the robot appears in simulation
  • Collision properties: Collision detection geometry
  • Inertial properties: Mass, center of mass, and inertia tensor
  • Transmission information: How joints are actuated

SDF (Simulation Description Format)​

SDF is Gazebo's native format that can describe:

  • Complete simulation worlds: Environments and objects
  • Robot models: More detailed than URDF
  • Sensor configurations: Detailed sensor properties
  • Plugin interfaces: Custom simulation behaviors

Practical Exercises​

  1. Create a simple robot model in URDF
  2. Simulate the robot in Gazebo with basic sensors
  3. Create a custom simulation world
  4. Implement sensor data processing in ROS 2
  5. Compare simulation vs. real robot behavior

Assignments​

  1. Gazebo simulation implementation
  2. Create a custom robot model with sensors
  3. Design a simulation environment for testing