Build an Artificial Hand

A robotics engineering project from Science Buddies

Key conceptsEngineeringRobotAnatomyGripping

IntroductionThe human hand is pretty amazing. You can do things such as pick up a pencil, use a video game controller or climb a jungle gym without giving it much thought. Building a artificial hand that can do all those things quite a challenge! In this project you will try to build a simple artificial gripper that can pick up small objects.

BackgroundThe human hand has five fingers, each with multiple joints. These joints are controlled by muscles and tendons—the muscles pull on the tendons, which pull on the joints and make them bend. The human hand has so many different joints, which makes it very flexible and versatile and easily adaptable to a wide variety of different tasks. You learn to use your hands as a small child, and by the time you grow up, you barely have to think about it at all!

Engineers have been trying to build robotic hands for years, but it turns out that this is very difficult. We have gotten pretty good at building robotic hands that are good at one specific thing. For example, a robotic gripper in a factory might be designed to pick up a certain part and bolt it onto a car. If you try to get that gripper to pick up a tennis ball or a glass of water, however, it will not work at all! Building a mechanical hand that is as versatile as the human hand remains a huge challenge.

In this project you will build a simple artificial gripper using drinking straws and string. You will cut notches in the straws that will act as the "joints" and thread strings through the straws to act as the "tendons." Pulling on the strings will cause the joints to bend. You can experiment with building different types of grippers, for example a simple clawlike gripper that just has two fingers with one joint each or a full humanlike hand with individual control of multiple joints.

Materials

Preparation

Procedure

Observations and resultsYou should be able to build an artificial hand that can pick up light objects, such as ping-pong balls, empty plastic bottles or small stuffed animals. It will be difficult to build a hand out of straws and modeling clay that can grab heavier objects. If you want to build a stronger hand, you might be able to replace the straws and clay with sturdier materials from a hardware store (for example, plastic piping for the fingers, metal cable for the tendons and a wooden base with holes drilled in it for the palm).

It is much easier to build and control a hand where all the fingers and joints are controlled by a single string (similar to the "arcade machine"–style claw, where all the fingers open and close at once). It is much more difficult to build an articulated hand with multiple joints that are controlled individually—but that should not discourage you from trying! Remember, your own hands are very complicated, and professional engineers are still struggling to this day to build a fully functional robotic hand that is equivalent to a human one.

Because this is an engineering design activity, there is no specific formula to follow in building your hand. Designs can be very different, and there is no "right" or "wrong" way to make it. You might find some designs to be better at performing different functions. If you built different hands with different numbers of fingers, which one did you find to be the most versatile?

More to exploreGrasping with Straws: Make a Robot Hand Using Drinking Straws, from Science BuddiesYour Wonderful Hands, from Kids' HealthScience Activities for All Ages, from Science Buddies

This activity brought to you in partnership with Science Buddies

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