I Built a Thing to Explain PID

When talking about PID controllers to people outside of control theory, I wanted a thing that lets me actually demo a PID controller, so I built this device, and its a perfect teaching aid.

Return Normalization

There are a lot of RL posts and papers that discuss return normalization. This post discusses a problem with a common strategy, and my attempt to fix.

URDF Templating

URDF files let you explain the physical characteristics of your robot to a physics engine. Thats great. The bummer is the files tend to get long, and they are in XML (sigh).

Here is a small automation attempt using the Mustache template engine.

Meena – for Meditation

Weekend Side Project: Meena is a small wooden box containing a timer and a striker, which is intended to strike an instrument like a singing bowl or gong. Used for meditation.

Cascading Control PID Tuning

Beaker is a two-wheeled balancing robot. Here we build a low-level controller that maintains desired wheel rotational velocity, and discuss tuning.

Transfer Learning with Beaker

Transfer Learning is basically a brain transplant – taking a neural net that was trained for one task, and applying it (or transferring it) to another task. Here I transfer from virtual to a real robot — just like in The Matrix!

Modeling Backlash

Imagine you have a motor turning a gear which turns another gear. Unless those gears are *perfect* (pro tip: they aren’t), you are going to have something called backlash. Here is how to model it.