Re: [PSUBS-MAILIST] manipulator

[pierre&marie <poulin.carrier@videotron.ca>]

Thanks for your reply Vance,

I know that positionning with pneumatic cylinder is easy with no load but
can be a nightmare with a load... I do agree with you that if the arm is
only used for lifting very small object, basic pneumatic would be
easyer/cheaper to use.

Dan, what "weight" do you plan to use the arm for? Me I'm more in the 10-15
pounds...

Anyway, I'll keep you informed of the progress!

Pierre Poulin


----- Original Message -----
From: <VBra676539@aol.com>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, June 29, 2004 2:54 PM
Subject: Re: [PSUBS-MAILIST] manipulator


> Dan and Pierre,
>
> There are control issues with the "backhoe" kind of design you are talking
> about. Remember that the more the thing weighs, the jerkier it is. This is
not
> important the first time you get it to move, but it sucks when you are
trying
> to get something done. If you doubt it, watch Don Liberatore from Harbor
Branch
> try to grab a moving sample with their old arm (rate controlled) stuck on
the
> front of 14 tons of submarine. The Galapagos trip had several examples.
>
> Consider a simple arm, pivot and rotate at the shoulder joint, and a claw
> open and close. If you want to get fancy, add a telescope section to the
middle
> of it. There are dirt simple ways to make that work. Phil Nuytton built a
3-way
> arm for that little 1-man thing (I forget its name, not the Deepworkers),
The
> air vents inboard through a 3-way valve, pretty much like the old HYCO
main
> ballast vent valves, That's speculation, as it has been awhile since I saw
the
> thing. But it was done with SS pneumo cylinders and flex tubing--about as
> cheap as you can get.
>
> For hydraulics, you have to carry a pump, then valve the fluid. Parker
> Hannifin (among others) has a lot of that stuff, but it ain't cheap.
Surplus
> cylinders and valves tend to be Russian tractor grade (read massive). Then
there are
> some really nice little electro-hydraulic packages and electric solenoid
> valves (Parker again).
>
> Look at the arm on the front of the Diaphus (PC-14) in Frank's book. That
was
> a square one, and as far as I know is still working.
>
> Vance
>
>
>
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