The ROV MAKER team went to Keelung City Anle High School on 2020/11/13 and 2020/12/11 to conduct STEM ROV assembly courses. This course is mainly combined with the campus discount program launched by the ROVMAKER team. Anle High School specially arranged eight groups of students to participate in this assembly course.
Assembling STEM ROV is a very interesting and challenging course. Although it is only an elementary course for underwater robots, it covers electrical, buoyancy and waterproofing, which is very suitable as a Maker training course.
The courses are (1) frame assembly (2) thruster assembly (3) rov control box assembly and (4) buoyancy test (5) test in water. In each sub-course, the students personally use the necessary tools to assemble each link, and the ROV MAKER team also shares relevant academic theories and mistakes they have encountered in the past assembly.
In the assembly of the rov frame, the student used water pipe cutters to cut the PVC pipes and used electric drills to drill the relevant parts, and finally assembled the SeaPerch-shaped STEM ROV with PVC elbows and tees. This is the slowest part of this course, because it must continue to ensure that students stay safe in the practice of using electric drills and pipe cutters.
For simple design, the buoyancy of the STEM ROV does not come from the pvc pipe itself, but from the foam. The length of the foam determines the amount of buoyancy provided. It is recommended to launch the test after the entire STEM ROV assembly is completed, and then determine the length of the foam and cut it based on power the vertical thrust and the diving performance desired by the user.
The foam might shrink in volume due to water pressure. It is possible that the buoyancy of the compressed foam may be insufficient due to the deep dive depth and the STEM ROV cannot naturally rise. Some experienced makers use sealed floats instead of foam.
The following propeller assembly uses a simple method commonly used on the Internet, the film box, 365 carbon brush motor and wax bowl ring to achieve simple waterproofing.
This sealing method is quite simple. The first is to drill the film box, and then the 365 brush motor is sealed with tape to prevent the butter from running into the motor through its heat dissipation holes when it is packaged. Before sealing, weld the power line to the motor electrode. The power line here uses the CAT5 network cable. The advantage is that it is easy to obtain and it provides four sets of twisted-pair wires for up to four sets of motors. Finally, apply butter on both ends of the motor and put it into the drilled coin box.
The only thing you should pay attention to in this step is to make sure that the motor can be energized and run before packaging, and to avoid getting thick butter on your hands because even soap is difficult to wash off.
Then use the strap to fix the packaged propeller at a specific position of ROV flame and install the propeller blades to the propeller.
The finale of the assembly course is the assembly of the rov controller. The ROV MAKER team specially designed a two-way PWM control board combined with joystick and knob control. The rov controller design allows students to give the ROV a very flexible setting space when assembling.
Students can control the steering of the motor by swapping dedicated twisted-pair wires to the the PWM output pins. This allows students to avoid the fact that the motor is running in the opposite direction after the propeller is packaged and cannot be remedied. users migh connect other devices such as LEDs to the PWM pin at the same time to sync with with PWM control.
Even if the PWM control board is connected to the wrong thruster, students can switch the joystick/knob connection to dedicated PWM controller board linked to specific thruster .
The rov controller is a square box. Before encapsulating the it,students can decide the direction of the control line first, and then cover the upper cover of the rov controller for packaging.
The control box uses a joystick to control the horizontal thruster and a knob to control the vertical thruster. This allows students to use the joystick to easily control the ROV forward and backward or even turn in place, and the knob to control the vertical thruster to control the ROV to maintain a certain depth in the water.
After the assembly is completed, the final launch test is carried out. This is one of the best time to determine ROV buoyancy (foam tube length), and students can also confirm ROV performance at the same time.
Thanks to the students from Anle High School and the ROVMAKER team for participating in this ROV assembly course for teaching each other.
If you are interested in water pipe ROV assembly, please refer following Link.