Foldable Paper Robotic Gripper

Background Information for Teachers

Paper might not be the first material that comes to mind when you think about robots, but there are some surprising advantages to using it as a construction material. Paper is cheap and readily available. This makes it easy to build a robot from paper, even if you do not have access to more expensive tools or materials. Paper is very fast to cut, so you do not have to wait hours to make parts like you do with a 3D printer. You can make moving parts with paper by making folds that can bend back and forth, so you do not need any additional materials. Paper is also very strong for its weight (engineers say it has a high strength-to-weight ratio), allowing you to design sturdy but lightweight structures. Of course, there are some disadvantages too. You probably do not want to get your paper robot wet or expose it to flames! Thinking about advantages and disadvantages of different materials is something engineers do as part of the engineering design process. You can encourage your students to think of advantages and disadvantages of different materials as part of this lesson.

Image Credit: Ben Finio, Science Buddies / Science Buddies
Figure 1. A hexapod robot made from foam board.

In this project your students will make robotic grippers and use them to pick things up. Inspired by origami, the entire gripper is folded into a three-dimensional shape from a single sheet of paper (Figure 2). The simple gripper has two "fingers" and two tendons. Pulling on the tendons makes the finger joints bend, just like the fingers in a real hand. Your students can follow the steps in the lesson procedure to make the gripper shown in Figure 2, then use the engineering design process to try to improve the design and make it better at picking things up.

Image Credit: Ben Finio, Science Buddies / Science Buddies

The gripper consists of two finger shapes and a base where two thin strands, or tendons, enter. Below is a cut-out cardstock template with dotted lines that indicate where to fold.

Figure 2. The robotic gripper (top) and the paper template used to make it (bottom).

Additional Background Links

• Engineering Design Process, Science Buddies

Prep Work (15 minutes)

• If you have access to a laser cutter, download the paper gripper template SVG file and use that to cut out the templates. Otherwise, download and print enough copies of the paper gripper template PDF for all of your students. You may want to print some extras in case students make mistakes and need to start over. You can print the templates directly on cardstock, print on printer paper and glue/tape to cardstock or manila folders, or print directly on printer paper (which will be the weakest).
• Decide how you will walk students through the assembly process. You can show the assembly instructions video or the assembly instructions PDF on a projector. You can also print out copies of the assembly instructions PDF for students to work from at their own pace.

Engage (10 minutes)

Ask your students what materials they think of when they think of robots. Students might have seen metal robots in movies or have plastic toy robots at home, but do any of them think of paper? Discuss some of the potential advantages and disadvantages of using paper to build a robot (see background information section). Explain that today they will build simple robotic grippers by folding paper.

Explore (40 minutes)

1. Distribute the pre-printed or pre-cut templates.
2. Walk the students through folding and gluing the grippers one step at a time, as shown in the assembly video or the assembly instructions PDF. It is important to hold each fold in place until the glue dries completely. If you let go too early, you will have to re-glue that step and start over.
3. Allow students to try picking up a variety of objects with their grippers. They should hold the center section of the gripper and pull on the tendons to pinch the fingers together.

   How well can the grippers pick things up? Are some objects easier to pick up than others?

   What changes or improvements could you make to the gripper to make it better at picking things up?

4. If you have more time, allow students to modify the grippers by attaching other materials. (For example, they can wrap rubber bands around the fingers to give them more friction.) Can they improve the performance and make the grippers better at picking things up?

   What are some advantages and disadvantages of adding other materials to the grippers?

Reflect (10 minutes)

Discuss your results as a class. What objects were easier to pick up with the grippers? What could be improved about the gripper design? What about the process to make the grippers?

If students modified their grippers, discuss those results as well. Let students show each other their modified grippers and how they work.

Make Career Connections

Discussing or reading about these careers can help students make important connections between the in-class lesson and STEM job opportunities in the real world.

Robotics Engineer

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Career Profile

Robotics engineers design all types of robots, not just those made from paper! Robotics is a very interdisciplinary subject at the intersection of electrical engineering, mechanical engineering, and computer science. This project falls more under the area of mechanical engineering, but other robotics projects are a great way for students to explore their interests. Read more

Lesson Plan Variations

• Let students make their own gripper designs instead of using the template. They can use the template as a starting point and use a pencil and ruler to draw a modified design based on the original. This requires careful planning since any changes to the 2D design can affect the folding process and resulting 3D shape.
• You can have students use a 2D CAD (computer-aided design) program to design new grippers instead of drawing the templates by hand. You can also use a vector graphics program like Inkscape to edit the SVG file.
• Organize a classroom contest with a clear objective: for example, successfully picking up the heaviest object, or picking up and transporting the biggest variety of objects from one location to another without dropping them. You can also extend the length of the tendons and attach the gripper to a robotic arm, as shown in our robot hand with drinking straws project. You can even have a contest to see from how far away the students can pick up an object.
• If you want to incorporate Arduino into your lessons, can your students motorize their grippers? See the Science Buddies project Motorizing a Robotic Hand and our Arduino tutorial series for reference.
• This more advanced gripper design requires much more intricate folding, but the resulting device keeps the finger surfaces parallel to each other as they move. This can be useful for gripping flat sheets or rectangular objects. Left-side and right-side PDFs are available for printing and hand cutting from two separate sheets of paper that must be glued together. Alternatively, you can use the SVG file for laser cutting. (You will need to mirror the file to cut from a second sheet.) For instructions, watch the following video or follow the steps in our advanced gripper assembly PDF.

https://www.youtube.com/watch?v=mhPrxoMnVds