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Funky Robotic Hand
seldo writes "The BBC is carrying a story about a funky-looking robotic hand with the full range of 24 hand movements (NASA's best effort so far has 12, apparently). It's supposed to be for the disabled, although a spokesman for the British Council of Disabled People points out that everyday tasks are not really what the disabled need help with anymore. I just want one to play with :-)" Update: 08/08 17:58 GMT by T : You may be reminded of the DIY robot head from several months ago -- a perfect match?
Pneumatic cylinders can only push(unless you draw a vacuum). However, it appears that it is not a cylinder, but some rubber hose. Rather interesting I say.
....wrapped in a tough plastic weave.... ....which shortens in a scissor action when pulled out, just like a Chinese finger puzzle. As the rubber tube fills with air it is forced to expand
From the website:
The Air Muscle consists of a rubber tube covered in tough plastic netting which shortens in length like a human muscle when inflated with compressed air at low pressure.
The Core of an Air Muscle is a rubber tube....
The type of pneumatic muscle that you refer to use a pneumatic piston. These work differently. These muscles use a pneumatic bladder that, when inflated, cause the muscle to contract. This is the same behavior, or the same effect, as real muscles.
My thought is that the cycling of these pneumatic muscles will probably be somewhat noisy. There would be a hissing and poping sound from them as the inflate/deflate and the control valves are operated. I suspect that by using hydraulic muscles instead would be far quieter and would probably offer the device greater strength. The immediately obvious drawback to this is that the hydraulic method would likely have slower response times than the pneumatic version.
according to NASA the mean torque strength for their astronauts is 13.73 Nm. That would be comparable to the 1.5Nm that this robotic hand can do. i think.
Well, say 1 Nm at the proximal end - my index finger is (pulls out digital caliper) is about 90 mm from first joint to fingertip, so that's around 1 Nm/(0.09m)= 11.1 N, or about 1.1 kg worth of force (2.5 lbs) at the fingertip, if the finger was kept straight. Not very much, in other words.
Certainly, these are measurements of torque. Given that we can convert imperial to english.
Newton metres (Nm) x 8.85 = Pounds-force inches (Ibf in; lb in)
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Wrist: 13.275 pound/inches
Distal: 4.425 pound/inches
Proximal: 8.85 pound/inches
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