Submarine must be a complex and vital machine for safety, but the principle it relies on is quite simple. Buoyancy is variable. By pumping water into and out of the water tank, the ship can control its depth. The brick experiment channel has a series of Posts detailing the construction of a working submarine, the shell of which is made of plastic pipes and the mechanical part is made of LEGO.
In this submarine, the buoyancy box is a syringe operated by LEGO motors. The propulsion comes from a pair of LEGO motors, which are driven by ingenious magnetic couplings to avoid shaft seals. In order to monitor the depth, there is a laser distance sensor, a pressure sensor, and a raspberry PI zero to control the whole program.
In the following video, you can see that the spacecraft zips around the swimming pool at different depths, and then starts a longer journey along a shady stream. This is a very practical submarine. We hope to have a try.
This is version 4.0, which shows. We saw version 3.0 last year. This is definitely not the first submarine we introduced. This is a submarine controlled by PVC.