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Troubleshooting Guide

This guide provides solutions to common issues encountered while establishing development environments, running simulations, or implementing code examples in this course.

General Issues​

Issue: command not found or permission denied​

  • Cause: Command either not installed, not in system PATH, or lacking execution permissions.
  • Solution:
    1. Ensure software is correctly installed.
    2. Check .bashrc or .zshrc file for correct PATH configuration.
    3. For permission denied, try chmod +x <script_name> for scripts or use sudo for administrative commands.

Issue: Slow simulation performance in Gazebo/Isaac Sim​

  • Cause: Insufficient hardware resources (CPU, GPU, RAM), high-fidelity models, or unoptimized simulation settings.
  • Solution:
    1. Verify system meets Minimum Hardware Requirements.
    2. In simulation settings, reduce physics update rates, decrease sensor refresh rates, and simplify visual models.
    3. Ensure using dedicated NVIDIA GPU with updated drivers.
    4. Run simulations in "headless" mode if visual rendering not critical.

ROS 2 Issues​

Issue: ros2 topic list shows no topics​

  • Cause: ROS 2 domain ID mismatch or nodes not running.
  • Solution:
    1. Ensure all ROS 2 terminals have same ROS_DOMAIN_ID environment variable set.
    2. Verify ROS 2 nodes are correctly launched and not crashing. Check terminal output for errors.
    3. Source ROS 2 setup files (source /opt/ros/humble/setup.bash and workspace install/setup.bash).

Issue: Package build fails with colcon build​

  • Cause: Missing dependencies, syntax errors in code, or incorrect package.xml / CMakeLists.txt.
  • Solution:
    1. Read build output carefully for specific error messages.
    2. Install missing dependencies (rosdep install --from-paths src --ignore-src -r -y).
    3. Check package.xml for correct dependencies and CMakeLists.txt for valid build commands.
    4. Clean build space and retry.

NVIDIA Isaac Sim Issues​

Issue: Isaac Sim fails to launch or crashes​

  • Cause: GPU driver issues, insufficient VRAM, or conflicts with other NVIDIA software.
  • Solution:
    1. Update NVIDIA GPU drivers to latest version.
    2. Ensure GPU meets minimum VRAM requirements (8GB+ recommended).
    3. Check for conflicts with other NVIDIA Omniverse applications.
    4. Try launching Isaac Sim with --allow-root if running as root (not recommended for production).

Issue: Robot models do not load or behave unexpectedly​

  • Cause: Incorrect USD/URDF file paths, malformed model descriptions, or physics properties.
  • Solution:
    1. Verify all paths to meshes and textures in USD/URDF files are correct and absolute.
    2. Check USD/URDF syntax for errors using validator.
    3. Adjust physics materials and joint properties ensuring stable behavior.

(More specific troubleshooting steps for individual chapters will be added as content evolves.)