Detailed Description

Tutorial 3: PID Control

This tutorial demonstrates using PID controllers with MuJoCo simulation.
PID control enables velocity and effort control modes by using motor actuators
instead of position actuators in the MJCF model.

Key concepts:
- Using demo_resources/pid_control/test_robot_pid.xml with motor actuators
- Configuring PID gains in config/mujoco_pid.yaml
- Position and velocity command interfaces
- Motor actuators for torque-based control

Resources used:
- demo_resources/scenes/scene_pid.xml (scene with PID robot)
- demo_resources/pid_control/test_robot_pid.xml (robot with motor actuators)
- config/mujoco_pid.yaml (PID gain configuration)

Usage:
    ros2 launch mujoco_ros2_control_demos 03_pid_control.launch.py
    ros2 launch mujoco_ros2_control_demos 03_pid_control.launch.py headless:=true