I've been lurking around for a few days and I like the site and the folks on it so I thought I'd join up.
A little about me :- not particularly young but very good looking
. Engineer having experience in designing hardware/ software.. a little machine shop at home and build/designed many contraptions.. but thus far not a ROV.A little about my project:- There is a mechanical latching system under water that controls so gates and during maintenance I need to be able to visually check if these latches are engaging/disengaging fully. I have toyed with all sorts of ideas on how I could attach a camera to the latch and get the video to the surface but I can't have an umbilical connected to the camera if it's connected to the latch as the latches get moved about with a crane. Anyway this has led me to believe an ROV is the way forward. MAX depth 30m and pretty clean fresh water.
My thoughts on my ROV .
Body:-
Main chamber made of 100mm PVC waste pipe with screw on end caps.
Acrylic dome mounted to the front cap for camera viewing.
Two floats above the main chamber forming a bit of a V a little like the enterprise on star trek. I'm hoping this will give me a stable platform. Over all adjusted for as slight as possible positive buoyancy just so I don't kick up too much crap if I go near the bottom.
Motors :-
I was intending to use three brushless ducted fans for thrusters but the fellow from hobby king said they can only be loaded one way and if I tried to reverse them they would probably fail. So I moved on to out runners for the lower rotational speed and 40 or 50mm RC boat props. I would like these shrouded really and will have to give some though to how to do that. The problem I've got at the moment is finding cheap out runners with an esc that will do reverse. It seems to me a lot of the reversible esc's are used in cars and boats and for in runner motors. One CW and one CCW for the forward backwards thing and one for up and down. I'm guessing 200w motors will be ok for this ROV but have yet to get a proper feeling on if that is reasonable.
Kit :-
PTZ IP cam..
Depth sonar and hold system :- Hopefully I'll be able to adapt some cheapo Piezo transducers and work out the distance to the bottom with a sonar ping and then type in the depth I require and the ROV will hold at that depth.
Communication and command :-
Now this is where I may be deviating from the norm... and I haven't really got enough experience to know it will work but I think it should.
The max depth is 30m but distance from the shore (bridge) will be 50m or more.
So I intend to put a floating buoy with a WIFI AP , raspberry pi / Arduino in and a media converter and run fibre optic from there to the ROV. In the ROV will be a similar media converter then an IP switch with a port allocated to the Camera and another to the brains in a raspberry Pi or Arduino.
I can just have a simple rope then tied to my buoy and not have unnecessary drag from a long umbilical. This set up also allows multiple folk to see the picture if they want as all they'll have to do is log on the AP with any device..
I'll be sending the controls from my laptop to the AP and thus the ROV and can move around freely.
Positional Sonar :- I haven't clue if this will work but I could have maybe six ultrasonic receivers (again hopefully these would be cheapo piezos) in a ring around the buoy in the water probably encapsulated in a mineral water filled thin ally pod. The RPI in the Buoy can send a ping command to the ROV and the ROV fire off a ping from an ultra sonic Transmitter (Piezo) . Then by listening to the receivers and working out the time differences it should be able to accurately locate the ROV and feed back that location to me at the top (X,Y,Z). If this works it will make it some much easier to navigate to the latches as there are about 18 positions these latches could be in. I will normally only be interested in 6 of those per dive but it would be a nice solution to be able to click on the latch position on my screen and the ROV go there. If I could stick an accurate GPS sensor in the Buoy then this really would be a handy easy navigation aid. But alas I could only get about 3m accuracy with a cheap GPS and that's probably too inaccurate to be helpful. I haven't thought of another way yet on how I can get and accurate fix on the Buoys position. maybe something similar to the underwater positional thing and that is to fire a longish wave radio signal at the Buoy and have an array of antennae and look for phase shifts in the radio wave to triangulate relative to the transmitter. I don't know if this would be feasible and isn't on my first to dos..
Opps sorry I hadn't realise I'd done such a big opening statement...sorry...
