A radio-controlled submarine that can maintain a steady depth or distance from the bottom using a pressure sensor, laser distance sensor, and PID control on a Raspberry Pi Zero 2 W. The hull is an acrylic cylinder with a syringe-based ballast system driven by a Lego EV3 motor. Tested in a swimming pool and a small river.
Nearly 30 million views of someone building something remarkable with Lego, off-the-shelf sensors, and Python.