I'm going to use one of these, it can reach 60-70 meters using an ethernet cable, max speed 12mbs -usb1.1. Already test it, and it works. You can find better ones that reach 100 meters but they are pricy. 60 meters is fine to start with.
Connection will be: pc----->usb ethernet converter----->60-70meters of cat5 cable----->ethernet to usb converter----->usb hub----->hd webcam(port1). / arduino mega(port2)
Does anybody knows if A 12mbs usb connection supports an HD 720p webcam??
The problem is that the computer will comunicate with the arduino, using serial comunication, on the same cable of the webcam. I'm not shore that 12mbs is enough for both. Any body knows how many mbs takes an hd webcam? Otherwise I can always use a normal webcam.
This is a drawing of the electronic connections inside th rov + some photos of the electronics box already finished.
The electronic box works at 12 Vdc. It contains:
Arduino mega
Relays for outside Leds
Relays for internal strip Leds (just for fun)
Relays for 2 motors direction (fw-left/bw-left+ fw-right/bw-right)
Tip31c transistors for motors speed
5v voltage regulator (for steppers)
Plus 2 smal pc fans for cooling the transistors and the volt reg
Motors:
We've bought 2 RE-540/1 dc motor (MFACOMODRILLS.COM) and propellers (different sizes to test, from 35mm to 50mm).
These will move the Rov underwater. One on the left and one on the right side, so you can go forward, backward, and 360 degres turning by giving opposite directions.
Behind the motors there are rudders (controlled by stepper motors) for going up and down.
The dc motor will stay in the water, because normal brush motor(and some brushless) can go undervater with no problem. The trick is to spray it with products like CRC Marine 6-66 or WD40.
Tests seem to confirm. I've only tried with unsalted water.