A refrigerator that chases you across the kitchen sounds like a party gag, but the wiring behind Dorian Todd's runaway mini fridge is the same split-brain design that runs warehouse robots and self-driving research rigs. One processor thinks, a smaller one drives the motors, and a serial link keeps them honest. Get that split working and you can steer almost any autonomous project a school robotics team dreams up.
What Dorian actually built
The fridge rolls on a tank-style track drivetrain turned by two Repeat Robotics Ultra Mk2 brushless gear motors, the same units built for 12-pound combat robots. Todd first sketched a six-legged hexapod, then dropped the idea once he pictured a stomping gait sloshing every carbonated drink inside. Pick a mode and the fridge either trails about a meter behind you carrying a cold drink, or bolts the opposite direction the moment you reach for it.
The two-brain electronics
An NVIDIA Jetson Orin Nano Super running Ubuntu and ROS 2 Jazzy does the heavy thinking. A YOLO model accelerated with TensorRT spots people in real time, and the ROS 2 Nav2 stack builds a live obstacle map from a Manifold Tech Odin 1 module that supplies depth sensors, an RGB camera, an IMU, and onboard SLAM. The Jetson then hands off to an ESP32 acting as the robot's spinal cord, sending a four-byte serial packet that carries the drive command and the door position. The ESP32 turns that into motor and servo signals, including a 25 kg-cm servo that swings the magnet-latched door open on cue.
Build a smaller version yourself
You do not need a Jetson to copy the pattern. Wire an ESP32 to a pair of motor drivers and one servo, then feed it short serial packets from a laptop or a Raspberry Pi running a lightweight person-detector. Keep every packet a fixed four bytes so a single dropped byte never desyncs the two boards, and tie your grounds together: Todd rewired the fridge's cooling loop to a 12-volt supply, so the logic and power rails must share a common reference. Watch Todd's full teardown on Hackster before you scale the idea up.
Originally published on blog.circuit.rocks.
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