The underwater remote operated vehicle or R.O.V is a submarine that drives around underwater and is controlled from above water, this also has a camera mounted on the R.O.V that relays a live feed to an L.C.D screen. This Instructable is based on my VCE systems engineering project for 2013, also this instructable is not a 100% step by step tutorial but goes through mostly everything you need to know to construct this, and with a bit of extra research by yourself you will be able to build a fully functioning submarine!
Step 1: Designing
Designing the R.O.V is very important. The more time spent researching and testing ends up saving you a lot of time when it comes to constructing the R.O.V, this due to finding small faults and possible complications before they arise. The first stage of designing my R.O.V was the wiring diagram. As majority of technicalities were electrical based the wiring diagram that was designed worked first shot with no complications, this due to research and consulting an electrician (my brother). The second stage of designing is researching materials and their suitability to the task, example: I used PVC pipe for the frame, as it is strong, light, waterproof and reasonably affordable. (attached to this step is an explanation of the wiring diagram, the wiring diagram is the photo for this step!)
Step 2: Constructing: Measuring and Cutting PVC Pipe
The next step is measuring and cutting all of the necessary PVC pipe. (the image depicting the pipes positions)
Cutting list for frame:
20mm PVC 16 @ 70mm long
20mm PVC 4 @ 100mm long
20mm PVC 6 @ 350mm long
8 @ 20mm PVC elbow joins
12 @ 20mm PVC T-Piece joins
cutting list for camera and lights tube:
50mm PVC 2 @ 400mm long
50mm PVC 1 @ 60mm long
6 @ 50mm PVC End Caps
cutting list for ballast tubes:
40mm PVC 1 @ 160mm
2 @ 40mm PVC end caps
20mm PVC 1 @ 160mm
2 @ 20mm PVC end caps
Step 3: Construction: Constructing the Control Box
The control box has many components in it, Relays, Joysticks, LCD screen, Switches, perspex, hinges, Din rail, wire, relay holders, terminal blocks and 12v 3 pin jacks. firstly, i purchased a hard plastic "safe case" from super cheap auto for 20$ next i mounted the joy sticks as seen in the photo (i purchase these from ebay for $5 each) to the perspex panel in which they sit on, from here i then glued them on and wired them to the relay holders precisely following the wiring diagram! after this i mounted the din rail to the inner side of the box and then clicked the relay holders onto this. for the propulsion of the craft, bilge motors are used as they are waterproof and suitable for the task, the output wires that join the motors to the relay holders are joined to 12v jacks, this means that the control box can be fully disconnected from the craft and, these 12V jacks are located outside the control box as seen in the photo. the top switch seen in the perspex panel is a booster switch that turns 3 relays on at once supplying power to the 3 directional motors on the craft, when this switch is off the middle forward bilge motor is turned on by itself and then the two outer motors can be used for turning the craft, but having the booster switch on gives the craft a "fast mode" that turns the 2 turning motors on and the 1 foward motor on. The second switch, seen as the bottom switch is for turning the lights and camera on, wired directly to the lights and camera pins on the 12v jacks this simply switching positive (+) on and off therfore turning the lights and camera on or off at the same time. the next step is mounting the L.C.D screen, this screen was purchased from ebay with a small camera sold as a car reversing camera kit for 30$, follow the wiring diagram supplied by the eBay seller and use simple electronic knowledge to wire the screen to the lights and camera on/off 12v jack. As the joysticks are fairly tall (75mm) the lid will not shut if you fix that perspex panel into a permanent position, this is where the hinges come into play, hinging the perspex control panel will allow you to tilt the controls up when you are using them and then tilt them down so the lid can be closed. Next you will need to run off 8 - 30m lengths of 2mm single insulated wire and 1 single core data cable for the camera, as the craft is not wireless these wires transfer the power from the controls to the craft. having the craft wired gives two benefits 1. it is cheaper than setting up some sort of wireless sonar system and 2. if the craft does become stuck you can pull on the wired and free it. (the photos show the wire rolled up on the hose reel, a hose reel can be used as it is easier to role the wires up neatly!)
Step 4: Construction: Mounting Components to R.O.V
When mounting the components the positioning of the components is very important, as when the craft is in the water it needs to be balanced and neutrally buoyant (not float or sink) so having the craft un-evenly weighted means a lot of time and additional weight or flotation materials to be used, This is why i have placed the bilge motors which are the main mechanism of propulsion in the center of the craft this meaning that the majority of the mass is acting through the center of the R.O.V (which is good!) when mounting the motor for elevation up and down i have also put it in the center of the craft and have fixed it there using a bracket i made that tightens onto the motor via threaded rod that extends through the PVC tube, the propeller is from an old microwave exhaust system. When mounting the lighting and the camera these must be water tight as they provide a form of buoyancy and as the light tubes run the length of the craft this provides a huge amount of stability through the water. The camera tube is also the central wiring point where the wires from the above water controls and the motors/lights join, so this is very important to be waterproof! where the camera is located (the middle pipe on the photo) you can see that there is a small window for the camera to look out of and for the lights (left and right tube) to shine out of, this was simply done by cutting a hole through the PVC end caps and using silicone fixing a perspex circle into the base of the cap. now that everything has been mounted to the frame it is time to achieve neutral buoyancy so the craft can sit level in the water, this can be done by firstly drilling holes in the underneath side of the PVC frame! (do not drill holes in the lights and camera tubes!!!!) this will flood the frame and give it some weight, your results may vary but when i achieved neutral buoyancy i needed a little extra weight at the front and the back of the craft, using the Ballast cutting list tubes, and fixing them to the underneath side of the front and back of the craft using hose clamps I filled both full of small pebbles and found that the front needed more weight than the back (hence the bigger pipe size 40mm) and so i continually added weight to the front until the craft sat just under the water level. note* the weight of the wire will effect the buoyancy of the craft, so i added small cubes of high density foam for flotation, this taking alot of strain off the craft. and also note* the neutral buoyancy will vary in salt water and fresh water, less ballast weight will be needed in salt water.
Step 5: Finishing Up!
When everything has been completely finished and works, go over the craft with a few coats of spray paint, making sure you cover the lenses for the camera and the lights with masking tape so you do not paint over them. Here is a video i made that shows my R.O.V being driven around a pool! Also the photo of the fish was taken when i attached my go pro to the front of the R.O.V, this was taken at a depth of 2-3m when i was controlling it from the beach shore.