I am a Teacher in Cairns and we are looking at making submarines from Micro:Bits. The submarine will have 3 motors and an light. I envisage that “tilt left” will be left, “tilt right” will be right, “tilt forward” will be down and “tilt back” will be up. Pressing buttons “A” and “B” will be start and pressing button “A” will turn on a light.
From this I guess I am after a break out board for the micro:bit, three suitable motors and a suitable light. They do not need to be waterproof as this is something we will need to work out.
Interesting, so will you have a neutrally buoyant collection of wires leading down to your sub? (with a waterproof Gromit to connect to a waterproof container, I found that having too low of a gauge caused the drag to increase almost exponentially) I had an extremely similar project that I put together a while back, and one of the biggest issues was wireless signals being blocked, particularly in saltwater. You should be able to program the functionality for button based control directly on the microbit using GPIO, as for a driver, it depends on the type of motors that you intend to use (personally I used servo motors), the link below could be a suitable board to perform all of these functions, depending on the access you require in the sealed space that you’ve got. (using non-waterproof motors with servo horns extending into the water via a waterproof connection was the option I used on the ROV).
If you have any further questions please let me know.
From the sounds of things if you are developing this as a class project I would actually recommend leaving the MicroBit out of the water and getting a DC motor which will work underwater. That way you won’t have to worry about waterproofing the ROVs and they can just be a frame. But, the product mentioned above by Bryce would be a good fit. Something like this could be controlled by a microbit: https://dronesrate.com/drones-types/homemade/drone-homemade-homemade-underwater-rov-google-zoeken/
Bryce is right when he mentions radio frequencies being no good under water, fresh or salt. If you figure out how to do it there are a lot of people who would be very interested.
It is done in some instances but requires an antenna floated to the surface or the use of VLF at some 200kW plus. Bit outside the average hobbyist capability.
Thank you all for your great suggestions. I totally agree that wireless is no go and I will use a wired solution, thanks Bryce for the board. The type of sub we want to make is exactly like the one Mitchell has a link to. As I am very new to this if some one could point me to the motors I will need and how to make/buy the propellers I would really appreciate it.
Excellent, if you’re intending on making the body of the sub, you can also print some propellors we offer a service for it if the students have some models are drawn up as STL then they can send through the appropriate files as listed in the product description. As for motors, in my version, I used a set of 6 12V bilge pump motors from some pumps I got and tore down very similarly to the part below and used some L298 H-Bridges in order to control them from an Arduino Mega although, for your project the Mega would likely be overcompensating, I was also running a series of sensors (ultrasonic, photoresistors, pressure sensors) of the GPIO, but you won’t need that in your case by the sounds of it, so you can likely use a Uno or another smaller board such as your micro:bit. (another trick I’d recommend is to build it all in a sealed piece of PVC piping filled with either sand or concrete to control buoyancy and a clear acrylic front panel)
(I used a high current variation of this, please be sure to limit the voltage so that you don’t draw over the maximum amount of 2A) For controlling speed, I used PWM at a fixed voltage instead of varying it directly.
(You may need the larger model version depending on dimensions)
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