May be here we could share new ideas about the ROV main body design.
My concept design:
I'd like to share what I have arrived to and would like to know opinions from you.
My starting point is .... This is a research project, hence crazy ideas, may give way to practical solutions.
My concept uses the original ROV electronics and robotics, albeit a few modifications would be required.
The ROV is governed by means of three propellers that allow for 3D motion. But Z axis is served by only 1 prop.
Dual propeller approaches are a solution, but I thought ..... How could I get the same result with only 2 props ?
From another point of view, I wanted to increase the working depth.
The question is .... What if instead of combining props thrust, that thrus is made directional as in bigger ROVS ?
And ... How to achieve this without increasing commanding requirements ? What is the same, using only three commands (3 motors control).
The solution I found is:
2 Motors are fixed to the end caps centers.
The whole electronics are set inside the Tube, supported by a frame that is able to rotate inside that tube by means of a wich-type servo.
When the inernal frame moves, the center of gravity moves as well, but the center of buoyancy does not move, hence, the frame holds its possition (with respect to the world coordinates), while the external tube rotates, and both motors with it, allowing for directional thrust.
That way, the same 2 propellers will work along 3 axis and not only two.
Supported by the main frame, another winch servo allows for camera rotation around a 180º arc.
Hence, only two ESC are required as only two motors are used.
Limited by the components sizes (mostly by the control board), the choice has been an Acrylic tube
OD 177mm; ID 158mm; L= 65mm, with two "submarine hatch covers type" for the end caps, 27mm thick, that allow for a working depth of:
From UnderPressure software, by Deepsea, 397metersFrom ABS rules: 393 meters.
Battery tubes, perhaps only one tube is going to be used, hanging below the main tube.
Three fins have been found to be required, being fixed to the motors mounting. Two of them, fitted at both sides, and a third one, between the proppelers ducts working as tail fin.
Hydrodynamic performance has been sacrificed for the seek of manouverability, camera angular range and depth improvement.
Some pics of the first design stages.
Control board and fixed framaing. (Two similar frames will be set at each side of the arrangement, with the servos and cam mounting between them).
The gear crown mounting can be substituted by rubber wheels.
All parts have been selected from standard catalogues.