What’s in the name Mini.S23? Mini refers to its small size, S23 refers to the summer of 2023 when I finished version 1, and . in between just seemed cooler than leaving a space at the time.

Version 1

Version 1 was mostly a mechanical test. I printed a PETG frame with regularly spaced M3 mounting holes, threw two mismatched hobby gearmotors and a RedBoard Plus (Uno) with a motor driver shield onto them, and wrote a controller that would make it drive in a few different patterns that could be selected by changing the code.

Despite its simplicity, I learned four things from v1:

1. My frame worked, but just barely because

2. My printer had a significant x-axis bar sag, so I had almost 10% error in my z-axis tolerance from one side of the bed to the other

3. The tiny support wheel in the back was more or less useless for anything except adding drag when trying to turn on carpet

4. Mobile robots without sensors are really really boring

Version 1.5 or 2.5 or something?

I have since removed the ESP32 from Mini and used it to setup my remote controller and test my differential-driving skills while working on the Asterius combot.

Version 2

The result of adding two free-spinning wheels to the back, an ultrasonic sensor and an ESP32-CAM was v2. The controller was a lot less finicky and incorporated the ultrasonic sensor to stop moving if something was directly in front of Mini.

The ESP32-CAM was mounted on top in a 3D-printed enclosure designed with mixed success to look something like the camera stack on the Curiosity rover. It allowed remote control of Mini over Wi-Fi using the camera to see where it was going.

Unfortunately I was only able to spook my cat with v2 a few times before I started messing with the vision code, which was over my head, and I never got Mini running properly again that summer.