Homebuilt ROVs Forum

Alright, the title is slightly misleading. I have some basic ideas for possibilities for controls: I'm going to have either 5 or 6 motors (I want extreme maneuverability), an HD camera feeding live into a laptop, and some LED spotlights. So far asking for help through my ROV blog hasn't provided much in the way of responses, so I look at this forum as heaven on earth.

I've toyed with three possibilities for the control system:

1. Basic "Battery in box" system where all power is lead down the tether to the motors uniquely, all switches have full power running through them. Cheapest but bulkiest, and extremely inefficient for greater depths.

2. Relay control system, much like the retrofit Seafox (my personal fav). Small, but still, the cable has to have volume and signal can be lost over long distance. This is the control system I favour, due to simplicity vs. price.

3. This one is pricy, difficult, I know nothing about how to make it work, however it would be the most efficient if I could make it work. RC plane controller running down a single small copper wire to the ROV with some strengthening cable and the USB or A/V feed for the camera. I like doing everything myself and building all my own components (hence my favouring option 2), but this would be extremely cool, increasing the range and maneuverability of the unit.

Camera is all figured out, no problems there. All I'm concerned about is the controller. I favour the Relays for it, but I want to see what experience says about it. I want to stay away from option one, it's sort of like having an FA-22 available to fly but taking the Wright Flyer as the better option.

So, what do you think?

-Colin
Langley, Vancouver, BC, Canada.

If you want extreme maneuverability, go with option number 3. It will cost more, but you'll have a thinner tether, and fully proportional control of all you thrusters. If you want to go deep, you can rule option number 1 out, as voltage drop will become very significant when you have longer tether lengths. Option number 2 would work fine, so it's basically whether you want to pay the extra money for more precise control and a thinner tether.

I personally want complete control over ever system without any electronic gizmos getting in the way, so I think I'll stick with number two. One last question: My partner raised the point that the tether is more vulnerable to damage if I am using the relay system, as if one little wire were to break inside the insulating cover, fixing it would be a pain in the place that hurts. Is it very frequent that a wire failure occurs on these tethers?

I use the relay system in my ROV (you are right in that it is very reliable), and I've never had a failure in the tether. It would depend on what your strength member in the tether was, but I don't think it would be a big issue. You have to remember that either of the other two systems disscused could also have a failure. It may be to your advantage to have one or two extra wires in the tether, for either failures(rare that they may be), or future upgrades to your ROV.

when I read "extreme maneuverability", I imagine a system that gives you very precise control of the thrusters.

relays don't provide this.

you need to be able to modulate the speed of each thruster in order to place the rov precisely, especially if there are any water currents.

just my two cents.