ROVs and buoyancy

Would anyone happen to know how buoyancy is designed into ROVs? I don't necessarily mean the specific flotation devices -- I just mean the general principle(s) applied when designing it so it can maintain static positioning and stability underwater.


If I built my own ROV (for example), I would want it to be able to "hover" in specific positions in the without rising, sinking or drifting.


What sort of design elements make ROVs capable of doing this?

 

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PS - actually, could you also recommend any flotation or buoyancy devices while you're at it LOL

 

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I understand they a kind of foam made from epoxy filled with glass microballoons for flotation. The microballoons will not break or fill with water. That's all I know about it.

 

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You would most likely need a cylinder of compressed gas, and bouyancy tanks you can flood or drain (rather like a submarine). It may be worth noting bouyancy will vary with depth, temperature and salinity. Currents will also pose a problem. You should aim to construct it as slightly bouyant, then use ballast to keep it in trim.

 

my best guess would be a tank that can be flooded with water.
a bottle of pressurized air would force the water out.
by carefull adjustment a neural buoyancy can be had.

 

Most ROVs have a foam filled float - (although some simpler models just use a balsa float) - they then add weight depending on the salinity and depth they are plannign to use it at