Prereqs:
1. Have ROS1 Noetic installed
2. sudo apt-get install ros-noetic-urdf-tutorial

Part 1: Building a Visual Robot Model with URDF from Scratch
Docs: https://wiki.ros.org/urdf/Tutorials/Building%20a%20Visual%20Robot%20Model%20with%20URDF%20from%20Scratch

1. Initialize URDF with 1 shape
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/01-myfirst.urdf'

2. Adding another shape and a fixed joint
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/02-multipleshapes.urdf'

	- <joint> tag defines the relative pose of the child link to the base link

3. Fixing orientation of child part and physical part
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/03-origins.urdf'

	- <link> tag defines how the physical part is positioned relative to the child link

4. Changing the material of the parts
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/04-materials.urdf'

5. Adding remaining parts
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/05-visual.urdf'

Part 2: Building a Movable Robot Model with URDF
Docs: https://wiki.ros.org/urdf/Tutorials/Building%20a%20Movable%20Robot%20Model%20with%20URDF

1. Updating the urdf with joints so that the links can move
	- roslaunch urdf_tutorial display.launch model:='$(find urdf_tutorial)/urdf/06-flexible.urdf'

	- A continuous joint is a revolute joint that takes values from -inf to inf (e.g., head and wheels)

	- A revolute joint has limits for the possible angles

	- A prismatic joint only has translation with limits on how many meters the link can translate

	- The tutorial takes input values from the sliders and it publishes them to the /joint_states topic, which Rviz subscribes to actually move the parts

Part 3: Adding Physical and Collision Properties to a URDF Model
Docs: https://wiki.ros.org/urdf/Tutorials/Adding%20Physical%20and%20Collision%20Properties%20to%20a%20URDF%20Model

1. Before we can deploy our urdf into a simulator like Gazebo, we need to define some physical properties
	- <collision> tag defines the shape of the collision boundary of a part
		- Using simpler shapes to represent the collision boundary of complex mesh shapes is less computationally expensive

	- <inertial> tag defines the mass and inertia parameters of the part

Part 4: Using a URDF in Gazebo
Docs: https://wiki.ros.org/urdf/Tutorials/Using%20a%20URDF%20in%20Gazebo

1. Launch Gazebo with the urdf of the robot loaded and let a controller publish twist commands to move the robot in the simulator
	- roslaunch urdf_sim_tutorial 13-diffdrive.launch