Follow these instructions to learn more about how hands work. All it takes is a little cardboard and string.
You will need
- 5 pieces of card (5 cm x 20 cm)
- 5 x 30 cm string
- sticky tape
- heavy cardboard.
What to do
- Take one of the pieces of card and use your pencil to place a mark every 5 cm along both of the long edges. At each of these points, cut a triangle with sides of approximately 1.5 cm. The tip of each triangle should point directly at the tip of the triangle on the opposite edge of the card.
- Repeat this step for each of the pieces of card.
- Roll each card into a long tube and sticky tape the long edges together. You should now have five cylinders with diamond-shaped holes down one side. These will be the fingers, and the holes will be where they bend.
- Tie a knot in the top of each piece of string. Thread one string through the middle of each finger and tape it near the join at the top.
- Cut the heavy card into the shape of a paddle. This will form the ‘palm’ of your hand.
- Tape each of the four fingers onto the palm with the holes facing ‘up’, away from the palm. Tape the fifth cylinder, or ‘thumb’, pointing out of one side of the palm. Use your own hand as a guide on how to arrange them.
- Pull on the string of each finger. Can you make a fist with your robotic hand?
We use our hands to do some delicate work. The muscles that make them move can be broken into two groups – the ‘extrinsic’ and the ‘intrinsic’. Intrinsic muscles give you the fine control of each finger, allow you to spread them out and move them from side to side.
The extrinsic muscle group allow you to bend and point your fingers. You have some extrinsic muscles on the underside of your forearm called ‘flexors’, which are joined to each of your finger bones (called phalanges) by long, thin tendons. The string on your robotic hand acts much like them. The muscle group on the back of your forearm are called ‘extensors’, and are also joined to your phalanges by tendons.
Many muscles in your body work together with a partner as part of an ‘antagonistic pair’. For example, you can bend each arm at the elbow thanks to your bicep muscles, and extend it again thanks to its antagonist, the tricep muscles.
Making robots that work just like humans is extremely difficult. While our muscles, tendons and bones all act like a living machine, they are far more efficient than many of the synthetic materials we have come up with. Researchers are still working on making chemicals that can shrink and expand with the same strength as muscle, to remove the need for hydraulic pumps or gas-filled pistons in most modern robots.
Our brains do a great job of coordinating our muscles. However, in a robot, a computer has to take its place. As microchips get smaller and computers become more efficient, it’s possible we might find better ways of mimicking many of the brain’s features. Tiny computers can already mimic some of our senses, such as implants that help people hear.
There’s no doubt that the human body is an amazing machine that is difficult for us to copy. As we learn more about chemistry and biology, we can find better ways of helping people who have lost organs or limbs through prosthetics and robotics.
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