On Mon, 16 Oct 2000, Andy Shaw wrote:

> Just a quick note here. The way I like to run my subs is not to spend ages
> ballasting them so that taking on a full tank of water takes them to a
> neutral buoyancy (which is what most people do). Instead what I would like
> to do is to automate this part so that I can just do a simple pond side
> set-up of taking on water until the sub is neutral then store the value
> associated with this state in eeprom. Then I just command the sub to take on
> the same amount of water when I dive. I currently do this open loop (timing
> based) but this tends to be a bit hit and miss as the batteries go down...

Just a thought:  There are available pretty accurate flow meters, as used
in automotive applications to sense fuel flow.  Couldn't you use one of
these (or even a home-brewed one using a paddle wheel and slotted disk or
whatever) to measure how much water you pump into and out of the ballast
tank?

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
                -- Isaac Asimov

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