In the An Introduction to STEM ROV, first post of the STM ROV production sharing series, it is mentioned that STEM ROV is an educational kit, which is derived from cheap materials available in daily life. Therefore, choose a carbon brush motor instead of a brushless motor in the propeller. This choice is basically based on (1) cost (2) waterproof and (3) power supply system considerations.
For cost considerations, the price of brushless motors is much higher than that of carbon brush motors, and brushless motors must be controlled and driven by an Electronic Speed Controller (ESC), which is an additional cost. The carbon brush motor only needs to supply DC working voltage.
From the perspective of waterproofing, if using a brushless motor, the waterproof issue of the ESC must also be considered.
From the perspective of the power supply system, the use of brushless motors will lead to more complicated wiring distribution than carbon brush motors. STEM ROV control/power transmission line may not be able to use normal CAT5E network lines, not only the number of wires that can be used but also the power that can be withstood.
In the choice of carbon brush motor for STEM ROV, you can choose 365 DC carbon brush motor, its size can fit into a film box.
The basic concept of the waterproof treatment of STEM ROV thrusters is to use the film box as the thruster shell and place the carbon brush motor in it. The two ends of the film box are filled with special butter to achieve waterproof effect. If it is for students to operate STEM ROV in the swimming pool, such waterproof treatment is sufficient.
This kind of waterproofing is actually very simple. This is a method that the Internet has known for a long time. It is suitable for primary and middle school students to implement and enter the field of underwater robots. The rough steps are:
- Drill holes at both ends of the film box
- There are many heat dissipation holes on the surface of 365 DC carbon brush motor, which are sealed with insulating tape
- Weld the relevant wires to the two electrodes of the motor
- Coat both ends of the motor with special butter to seal the film box
There is no standard for the selection of propeller blades and the fixation of the 365 DC carbon brush motor. It depends on the ingenuity of the maker.
In the thruster kit launched by ROV MAKER, we choose the forward and reverse blades as the thrust source of the horizontal thruster, and the processed connector makes the installation and removal of the blade easier. Interested readers can click on the picture below to understand our product.
The ROV MAKER team provides the following video to share the example of the introductory water pipe ROV (STEM ROV) propeller production, for the teaching reference of each school!!