Building Rocky: my Project Hail Mary desk robot
There’s a new project on the bench, and this one has legs. Literally. I’m building a desk robot, and if you’ve read Andy Weir’s Project Hail Mary, you already know exactly who he is. Amaze.
For the unfamiliar: Rocky is the alien engineer from the book, and he’s the perfect character to build a beginner robot around, because every one of his traits maps onto easier tech, not harder.
He’s blind, so there’s no screen to drive. One whole component category, gone.
He perceives the world through echolocation, which means the humble ultrasonic distance sensor, the first sensor every robot tutorial reaches for, isn’t a compromise here. It’s canon. Mine will sweep side to side on a little servo, which is both more useful and more alive.
He speaks in musical chords, not words. So instead of wrestling with speech synthesis, Rocky gets a small speaker playing note sequences: rising fifths when he’s happy, a warbling chord for a question, something properly dissonant when he’s alarmed. Easier than voice, and honestly more charming.
Eridians like it hot, so there’s a temperature sensor purely so he can grumble in low, sulky chords when the room is cold. Is this necessary? No. Is it essential? Yes.
Add downward-facing cliff sensors so he doesn’t echolocate his way off the edge of the desk, and a rock-ish shell over the top, and that’s the whole creature.
Standing on a very good robot’s shoulders
The plan isn’t a from-scratch build. There’s a lovely open-source desk robot called Sesame by Dorian, explicitly designed to be forked and remixed, and Rocky is going to be exactly that: Sesame’s bones with an Eridian soul.
What survives from Sesame: the servo and gait code (walking is hard, and this walking already works), the animation workflow for designing his moves, and the power management, including a staggered servo startup that stops the whole thing browning out on boot. That last one is the kind of hard-won knowledge you gratefully inherit rather than rediscover at 11pm.
What gets replaced: Sesame is driven from a phone over WiFi, and a desk pet you have to remote-control is a toy. Rocky gets an autonomous behaviour loop instead, the classic robot-pet architecture: a little state machine running forever, idle, wander, notice something, react, back to idle, with the sensors feeding it and the chord library expressing whatever he’s feeling about it. The WiFi controller isn’t deleted though; it gets demoted to a hidden debug page, a backstage door for testing sensors and triggering animations while I develop. Rocky doesn’t need the phone. I do.
Which means the meaty part of this project is the code rather than the electronics, and that suits me fine. Code is free to iterate on, and it’s where the personality lives.
Where things stand
The UK parts order is sorted, the budget is pleasingly un-scary (well under £100 all-in), and the plan is written down, which for my projects historically counts as the halfway point. Next comes the part where theory meets soldering iron, and I intend to document the whole thing here, chord-related setbacks included.
Fist my bump.