Gripper Challenge Copyright © Texas Education Agency, All rights reserved.

First Challenge: Marbles Overview By looking at a human hand, we can tell that years of evolution have developed quite a sophisticated gripper, but a gripper simply means a device used to “grip” objects in order to pick them up. In this first challenge, you will need to construct some sort of gripper to best pick up marbles. Copyright © Texas Education Agency, All rights reserved.

Marble Challenge Having difficulty creating a gripper that works to pick up marbles? If you have created a gripper that works effectively, try using it to pick up differently shaped objects. Does it work? Using your own gripper, see how many marbles you can pick up in one minute. Copyright © Texas Education Agency, All rights reserved.

Challenge 1 Now pick up the marbles and objects using your own hand. Was it easy? It should have been. Can we conclude that the human hand is one of the best types of grippers to pick up objects? Let’s test this hypothesis. First let’s construct your own robot hand. Copyright © Texas Education Agency, All rights reserved.

Procedure: Robot Hand 1.Place your hand on a piece of cardboard and trace it. 2.Mark the points of your joints on the cardboard. 3.Cut out traced hand and fold at the joint marks (3 folds per finger except thumb). See Figure 1. 4.If necessary (depending on the type of cardboard used), reinforce the cardboard hand with duct tape or insulating tape. This will allow for more control over the hand’s motion. 5.Cut up a straw(s) into several one centimeter (or slightly less) long pieces. 6.Glue cut up straw pieces between fold/joint marks on the top and bottom of each finger. Figure 1 Copyright © Texas Education Agency, All rights reserved.

Procedure cont. 7.Glue remaining straw pieces on only one side of the of the hand as seen below. 8.Attach rubber bands (red lines in Figure 2) to the side of the hand that only has straws on the fingers. Slide the rubber bands through the straws and either glue them down or staple them down so that they are stretched out ever so slightly. The hand should still be flat as seen in the picture. 9. Attach string (green lines) to the tips of each finger and slide the rest of the string through the remaining straws (Fig. 2) Figure 2 Copyright © Texas Education Agency, All rights reserved.

Procedure cont. 10. Attach hand to some sort of base (i.e. ruler, PVC pipe, etc.). See Figure 3 and 3.1. Figure 3 Figure 3.1 Copyright © Texas Education Agency, All rights reserved.

Challenge 1 cont. Record how many marbles you can pick up in one minute with your first gripper and then how many you can pick up with your hand. Which one was more efficient? Copyright © Texas Education Agency, All rights reserved.

Challenge 2 Now, using your newly constructed hand, pull on the strings in order to contract the fingers to make a fist. Try picking up the marbles and objects and placing them into a bowl. See Figure 4 and 5. Figure 4 Figure 5 Copyright © Texas Education Agency, All rights reserved.

Challenge 3 Using your gripper hand, try stacking up some type of blocks as seen in Figure 6. Does it work effectively? If not, construct a type of gripper that will. Figure 6 Copyright © Texas Education Agency, All rights reserved.

Do you think the hand gripper is the best type of gripper for all objects? Copyright © Texas Education Agency, All rights reserved.