Tutorial: Creating a URDF For Your Robot

Creating a URDF For Your Robot

What's a URDF File?

URDF stands for Universal Robot Description File. It describes, in a representative fashion, the following:

Where each of the links and joints are relative to each other
How each of the joints move
Encodes physical properties, such as mass or moment of inertia, collision/ visual volume

URDF Files are an important component in ROS architecture, because it provides a standardized format to let all of the generic packages know how your robot is configured, what its constraints are, etc.

Workflow

In a high level, the workflow below will let you generate a URDF file:

Install the Plugin
Create a Simplified Solidworks Assembly
- You don't want too much complexity, as calculations for collisions will take longer. Lean on the side of convex hull approximations.
- If you already have an assembly, it's okay to use them; instructions are in the supplementary link.
Setup a primary coordinate system for each of the parts
- Remember that, as per REP 0103, X axis is forward in ROS, and all coordinate systems are right-handed.
Setup an axis (if applicable) about which your part moves
- Again, Right Hand Rule! If you're unsure, you can simply flip the signs of the axes in the generated urdf file later.
Move over the generated package to your Linux Environment.
Modify the generated package so that it's compatible with ROS Indigo.
- Better documentation on this will come soon!

For a more detailed description, just navigate to the links below:

Links

Primary Link for the Solidworks Plugin

Supplementary Link for using the Plugin; much more exhaustive, in many ways -- includes gotchas. Once you're stuck, the most useful page for you is probably the last page.

Link to Relevant Repo : https://github.com/olinrobotics/edwin_description