[dorkbotbristol-blabber] The eyes! The eyes!

[Richard Sewell]

Ben - good stuff - sorry I missed the evening.

If it helps, I have a copy of the Gilbertson muscle wire book 
(http://www.amazon.com/Muscle-Wires-Project-Book-3-133/dp/1879896133) 
which you are welcome to borrow.

Although the wires have a decent pull force, it is only over a small 
distance, so we don't have a great deal of energy available for moving 
eyes. We might need to keep the eyes rather small and/or light in order 
to be able to move them. We'll know that once we have some actuators built.

As for eyes, how about polystyrene balls ? Available in many sizes, 
already mostly the right colour:
http://www.polystyreneballs.com/moulded-ball-price.asp

R.

ben winstone wrote:
> After a good brainstorming session last night I think we have some 
> nice ideas for the eyes. Anton has made an excellent prototype with 
> some wood and a pingpong ball. The momentum of thought seems to be pro 
> muscle wire for both cost and affect, but it may also be worth 
> pursuing magnets as an alternative. The trade name for muscle wire 
> seems to be Flexinol, and can be bought from rapid for about £8/meter. 
> It should safely reduce in size by between 3 & 5%, so some levering 
> would be required. It was discussed that we could replicate the 
> movements of real human eye muscles to perform the desired action.
>
> So we need to buy some muscle wire! I will try and buy a reel tonight 
> when I am home from work.
>
> David H has said we should be able to use the university laser cutter 
> to manufacture the parts out of acrylic or wood. We just need a dxf 
> cad file to give to the machine.
>
> With regards to overall design ideas we have disccussed that larger 
> eye would mean less of them and so less electronics and overall work 
> for us, making the project much more achievable. This probably means 
> an eye somewhere between the size of a ping pong ball and a football. 
> Any ideas of what we could use for the eye? Also some thoughts were 
> paid to the arrangement of the eyes.
>
> I brought along a working demo of OpenCv face tracking to show how 
> easy it is to use, and I know Richard is looking using an mBed 
> controller to interface with a simple camera for blob detection. Se we 
> probably have both sides end of the face tracking covered, but will 
> probably want to use some extra simple sensors to add context to the 
> presence of a human.
>
>
> Thats all I can remember for now about last nights eye discussion. 
> Keeps the eyes coming and lets get on to some prototyping!
>
> Ben
>
> 2009/10/27 Richard Sewell <richard at jarkman.co.uk 
> <mailto:richard at jarkman.co.uk>>
>
>     Anton Bowers wrote:
>     > I feel open loop would be better if it's at all possible, low
>     cost is
>     > more important than accuracy (assuming we want to make a low
>     number of
>     > hundreds of eyes).
>     >
>     >
>     Sadly, I don't think we can do open loop with muscle wire. It's got a
>     lot of built-in hysteris. Magnets & coils (or even bits of iron wire &
>     coils) ought to be a lot more inherently linear. Might be hard to
>     get a
>     large output angle, but perhaps that can be fixed with linkages.
>
>     I guess we need to make our trial actuators, then see if our ambition
>     stretches to two eyes or two hundred.
>
>     R
>
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