Tardygrade is my attempt to leverage some tried and true mechanical linkages into a simple yet capable robot walker. Rather than trying to emulate gait and leg articulation from biology, I started out with a mostly clean slate.
My only two guidelines were:
- Minimize the number of servo motors.
- If possible, use only 3D printed parts.
The design philosophy has been strictly utilitarian—function over form in every case. It was only after the fact I noticed that the thing ended up being rather cute, and looking a little bit like a tardigrade.
I've put a great deal of effort into making the robot body entirely 3D printable. Instead of screws or glue, Tardygrade relies on a combination ridges, snap fits and printer filament to keep itself together.
All in all there are 37 printed parts. Assembly should take about half an hour.
Automation control is based around the ESP32 µC. I'm designing a 5x5 cm printed PCB that acts as a shield for an ESP32 dev-board. The PCB has two pairs of pin headers, for compatibility with both the "Adafruit HUZZAH32 Feather" and the "Tinypico" form factors.
The shield has three main functions:
- Allows the ESP32 to perform motion control via four hall sensors, which detects the position of a magnet mounted inside the main gear.
- Voltage regulation for the servo motors.
- Hardware interface to laser distance sensors.
I'm also planning to add a downward-facing rgb led, to illuminate the robot body from within. There's no practical utility in doing that. I just think it would look cool.
The automation software is being written in MicroPython.
I will probably add some simple AI boilerplate that lets a Tardygrade fitted with distance sensors walk about autonomously. The boilerplate code can then be extended by users who want to experiment with their own AI code.
At some point I might start working on an Arduino port as well.
Open source, Tindie
For those who are interested in building this robot themselves, all relevant files will eventually be available for download. This includes:
- 3D printing files in .stl format.
- KiCad project or gerbers for PCB fabrication.
- MicroPython code for ESP32 automation control.
- Assembly manual
Tardygrade will probably also show up as a kit on Tindie at some point, if I can figure out a way of doing international shipping that doesn't cost more than the thing itself.
In that case people will have the option to get just the shield PCB and print the robot themselves. Or get the full kit if they don't have access to a 3D printer. The prints I'll offer on Tindie will use some higher quality materials like carbon fiber infused nylon, and maybe flexible filament for the legs.