Self-Balancing Things

As part of my interest in control systems, I've built or helped build a few self-balancing things. They all share the same basic angle sensing and control loop, but across very different hardware:

Seg...stick [Post Archive] [Instructable]
Mini-Segstick [Post Archive]
The DIY Segway [Static Website] [The Balance Filter]


Status: Completed.

I built Seg...stick in two days, mostly as a joke. It's a minimalist self-balancing platform based on two DeWalt power drills:

The whole thing costs less than $400 to make, and it does actually work at low speeds. It's definitely not the best self-balancing platform ever created, but this project is documented fully in an Instructable, so you can build your very own Seg...stick. Actually, I hope you don't. But the information and explanations there are applicable to any self-balancing platform.


Status: Completed and destroyed.

Mini-Segstick was born and died in a fit of rage lasting only about 36 hours. I thought it would probably take less time to build a self-balancing robot than to derive the equations of motion, which was Problem 1 of 5 on the MechE Controls Qual. So, while I should have been preparing for the oral exams, I took Segstick's controller and put it on a little two-wheeled thing that doesn't even have normal wheels. Needless to say, it worked fine. The next day, I tore it apart and that was the end of that.

The DIY Segway:

Status: Completed.

The very first Edgerton Center Summer Engineering Workshop (back before it had a name) project was the DIY Segway, a lightweight homemade self-balancing scooter that, at the time, was probably the simplest such build on the internet. It was made almost exclusively from FIRST Robotics kit parts and weighed about 50lbs.

As part of the project, I wrote up a simple(-ish) white paper about the complementary filter, and why it is the most logical option for angle sensing on a balancing platform.