[personal profile] caspian_maclean
Ever since Peter Hillier showed me the youtube video Skeletonics showing an unpowered mechanical exoskeleton that roughly doubles the wearer's reach I've wanted something like that.

However I wanted it to be cheaper and quicker to make. I am starting with just a single arm. My first version was a roughly 0.5 scale prototype made from plastic straws held together with sticky tape at both the plain joints and the rotating joints. It worked remarkably well initially though the sticky tape joins didn't last that long. I think it took well under an hour to make.

My second version was made from bamboo with bamboo sticks as the rods ($4.60 at Bunnings for more than I've used so far), cloth tape for the joins, and a $26 worth of bicycle brake parts to substitute for a hand. It took maybe 4 hours to make at the Perth Artifactory which had clamps and saws to cut the bamboo to length.

Issues with the current version:
The bicycle brake hand has a very limited range of motion. But it can still grip a can of soft drink.
With no straps yet, I have to hold the shoulder joint in place with the other hand.
The cloth tape keeps coming loose.
Some of the joints need to be quite loose for the sticks to be able to rotate past each other.

Well I've made the straw version and the stick version, if this is the three little pigs the next version should be made of brick. Unfortunately it's too heavy and brittle.

Possible upgrades:
Straps so it's attached to my arm instead of just held by hand.
Bolts through drilled holes instead of cloth tape. This will require adjusting the design so the rods stay out of each others' way.
Aluminium tubes instead of bamboo. The bamboo's worked pretty well so far though.
Cover the mechanism so it looks more solid. Could use metal foil or fabric.
Also I should get some more pictures up online. Jason put a video of me lifting a drink bottle with the arm here

I haven't worked out how I'm going to upgrade the hand yet. It may end up being more work and than the whole rest of the arm, it's already the most expensive part.



October 2011

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