Building a Lego-powered Submarine 4.0 - automatic depth control

This radio-controlled submarine can maintain a steady depth or a certain distance from the bottom. It is equipped with a pressure sensor and a laser distance sensor. Raspberry Pi and PID control are used for automation. Tested in a swimming pool and a small river (at the end of the video). Enjoy! 0:00 building 2:36 tests in water 3:48 long journey in a small river 6:47 full Python code SPECS Displacement: 2.4 kg (5.3 lb) Test depth: 1.5 m (5 ft) Hull: acrylic plastic cylinder (250x110x3mm), SAN plastic lid (2mm thick) Lid seal: o-ring 2.5 mm (NBR 70 shore) Ballast tank: 60 ml syringe (Eotia marinade injector), Lego EV3 Medium Servo motor (45503) Forward propeller: drone propeller (Diatone Bull Nose 4x4.5), Lego PF L-motor (88003) Turn propeller: Lego propeller 3 blade (6041), Lego PF M-motor (8883) Magnetic couplings: K&J Magnetics D38-N52 neodymium magnet, TapeCase 423-5 UHMW Tape, silicon spray Motor driver: 2x Pololu 2130 DRV8833 Dual H-bridge Radio control: 27 MHz controller dissembled from a toy submarine (no-name chinese Mini U Boat) Pressure sensor: Honeywell SSCMANV030PA2A3 2 bar Laser distance sensor: SparkFun TFMini-S Micro Computer: Raspberry Pi Zero 2 W Power supply: Lego Rechargeable Battery Box 9V (8878), Pololu 2123 S7V8F5 5V voltage regulator On-board camera: RunCam 5 Orange MORE DETAILS https://brickexperimentchannel.wordpress.com/rc-submarine-4-0-blog-post-series/ FULL PYTHON CODE https://brickexperimentchannel.wordpress.com/2022/07/14/rc-submarine-4-0-conclusion-10-10/ LONG JOURNEY VIDEO https://www.youtube.com/watch?v=rO5zHXUckKQ PREVIOUS SUBS 1.0 syringe ballast https://www.youtube.com/watch?v=tGEZApd9MMk 2.0 magnetic couplings https://www.youtube.com/watch?v=MdfUSNzc0Xk 3.0 balloon and compressor https://www.youtube.com/watch?v=n83cSg3wohU MUSIC Tommy Baynen - Stone Paths https://www.youtube.com/watch?v=zepP1zdiUPI https://colorize.ffm.to/0364 https://soundcloud.com/tommybaynen