Footwist, a tool to visualize 3D twists

I mostly think of rigid body poses in terms of 4x4 transformation matrices. For orientation, there are tools for visualization (example) and conversion between representations (3D Rotation Converter).

I was reading the robotics textbook by MLS to learn more about twists and screws. I made footwist (repo), a tool for visualization of twists and screws. You can specify a pose in the form of translation and orientation (as quaternion), and the tool calculates the equivalent twist and screw. It ends up demonstrating Chasles' theorem, which states that any rigid body transform can be realized by a screw. You could also use the GUI to update the twist or screw, and the other representations will be calculated.

The project was a good opportunity to learn some JavaScript. The linter I used (eslint with airbnb style) was a great teacher. The libraries I used were:

• mathjs for all mapping and conversions, basically implementing the math in the MLS book.
• three for very simple visualization. I could have also used three for a lot of the matrix math.
• lil-gui for the GUI, because that's what a number of three examples used.

Visualizing the screw that achieves a transform helps with intuition, but it's also fun to just play around with values.