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

LONG JOURNEY FULL VIDEO

CODE
or

PREVIOUS SUBS

MUSIC
Tommy Baynen - Stone Paths

[BrickExperimentChannel]

You can read more details of the building process here:

[PabloEdvardo]

Extremely cool. The visual clarity through the flat plexi in the front was actually astounding. This is a great proof-of-concept for a low-cost underwater remote filming rig.

[tarjaau]

10/10 Much safer than the Titan submersible

[AnilKumar-tiwd]

Your mechanically isolated and waterproof propulsion system is amazing and the whole project deserves top marks.
Well done!

[brotosstm]

Genuinely kind of ridiculous how far this project has come, I'm deeply impressed and proud

[gabrielmosoiu]

It's incredible and inspiring to me that you've gone from "how fast can I make a lego wheel spin" to making things like this. Not that there's anything wrong with asking the "simple questions" but it's really a beautiful thing to get so SEE someone come up with creative solutions to make their work better. Very refreshing in our time. Love your content!

[StopMoshin]

this dude cares more for the safety of his lego minifigures than Stockton Rush did about actual humans

[buggletude]

This is incredible. I'd love to see you test it's max depth. You could install some LEDs so that it the camera can still see at increased depth and tether it so that the sub can be retrieved once you lose radio control. Taking it to a lake should give you the depth and the relatively still water you need in order to test it safely

[MattTester]

I was already impressed with the syringe being operating using a Lego motor, then the magnetic drive and everything else means this is probably the most impressive thing I've seen this year. I wonder how much it could be scaled up...

[bricklejar]

Can't believe £200, 000 was spent on a sinking sub with the same controller and this cost around £100 and did the job just fine

[SHAHIDKhan-bpnz]

Everything about this video was awesome from the way you designed the submarine, to the magnetic coupling. But the best part of all was the underwater view as the submarine traveled. It looked otherworldly

[danielbuchanan]

As a qualified Submariner I appreciate the effort and time you put into this build and video. Getting into legos with my kids and a project like this would be so awesome.

[renehasselmeier]

30 years ago I tried making a Submarine from Legobricks and Pneumatic Psarts.I tried to create an Air Bubble in a separate Chamber. It did not work that well, as connections between Bricks were not waterproof or airtight. It was a Fun Bathtub experiment. You completed it right and i can now see my Childhood Plans working as intended. Thank you so much!

[iantaggart]

You have a knack for showing how Legos are more than just toys.

[kyles]

We need more of this 🤣 just go to random lakes/rivers, I could watch you exploring underwater for hours

[Caligari]

0:30 My mans legitimately using a lego router jig this is amazing 10/10 engineering. Love it.

[nochan]

TIP: Use acrylic cement rather than superglue. It will actually fuse the parts together forming a much strong er bond!

[Akklipz]

Suddenly was reminded of this amazing vid

[ljepic]

You never fail to impress me with these awesome builds

[arroz]

pretty satisfying, you really put this at the most of a submarine, and it's amazing how a river can look like another world from the submarine's view