Mechanical Arm

Mechanical Arm

Experiment creating extending arms and modify its properties to enhance it's grabbing capabilities.

Total: 45 minutes

Learning Objectives

  • Understand the basic function of a scissor mechanism, its properties and how changing them affects the overall movement.
  • Get to know a basic principle that leads to the law of the lever: “As the lever rotates around the fulcrum, points farther from this pivot move faster than points closer to the pivot”.
  • Understand the “accordion folding” mechanism as a series of scissors interconnected and the chain effect created by it.
  • Learn to make collapsible objects and how they can be easily transported and adapted.
  • Discuss the role of tools extending our manual capabilities: some tools might be good for a purpose or greatly used by a person but not adequate on other situations.

Imagine

5 minutes

alt

https://commons.wikimedia.org/wiki/File:STS-114_Steve_Robinson_on_Canadarm2.jpg

  • You can show the Mechanical Arm activity video and accordion folding mechanism images found on Downloads to students (Space arm, scissor lift, industrial robotic arm, deep-sea soft arm, etc). This can be assigned for viewing at home or during class.
  • Ask your students:
    • Why can’t you always pick up things with your own hands? Can they name an example of a situation? You can use funny, hypothetical examples such as handling smelly socks or for someone with a physical disability to use for reaching for something without having to get up.
    • To think about why and how a mechanical arm would be used in real-world situations.
  • If students are struggling to come up with ideas of how mechanical arms are used, it’s worth mentioning these mechanisms could be used to complete difficult repairs in outer space and conduct experiments in an intense ocean pressure environment. They also could be designed to be collapsible and store itself if on a moving vehicle. An arm is used for moving, placing, and picking up objects. They can be precise like human hands, be repetitive while consistent, and not endure fatigue while in a variety of environments.
  • Demonstrate with a built Mechanical arm grabbing an object from a table and reaching something otherwise unreachable such as an object on a high shelf or ceiling.
  • Exchange the pipes at the grabbing end of your mechanical arm with smaller pieces – shorter will create a tighter grab for smaller objects.
    • What happens if the grabbing end becomes really long?
    • What happens to the arm if you add bigger pipes to the accordion mechanism?
  • Ask students what they would like to build using the accordion or scissor mechanism.

Create

15 minutes

Activity
Make a Mechanical Arm

Make a Mechanical Arm

Make an extending grabber.
  • Allow your students to create a simple version of the arm first or skip straight to the reinforced version of it.
  • Let them know as they test their creations that they might have to adapt depending on the task they want the arm to perform. For example, changing the ends to be able to grab bigger or smaller items.
  • Let them know they can also introduce different pipe sizes and even different materials. Question them about how this would affect the movement and strength of the arm.

Play

10 minutes

  • While thinking of their mechanical arm design, have students also think of activities. Here are a few examples:
    • Activities that can be done collectively.
    • Something to hold a pen and write a name.
    • Something that can grab 3-5 different type of items. (something large, small, soft, hard, light, heavy, or far away. )
    • An arm that can hold something heavy and also collapse flat.
  • Let your students take the lead but guide them towards activities that explore more explicitly the arms properties.
  • If students are struggling to explore the mechanical arm properties in playful ways, propose a few challenges and games. One of them could be to try to pick up an object and pass to another grabber in the room. The challenge is to not let anything drop and you cannot touch the item with anything else than the mechanical arm!

Share

10 minutes

  • Pair students to combine their mechanical arms or to think of an activity they can perform together.
  • Let them take the time to share with their partners then to the entire class what they discovered while building their mechanical arms.

Reflect

5 minutes

  • Ask students:
    • What was something you discovered while building?
    • How did you feel when they tried something that didn’t work? Here you may encourage to think of failures as part of the process rather than something to be avoided.
    • What was the hardest thing to do with their arms and why? Did any arm design manage to do something that was hard for someone else?
    • What is the difference between the arm built and the “mechanisms” of their own arms and legs?
    • What is a possible way to control their mechanical arms without using their hands?

Preparation

45 minutes

  • Build a Mechanical arm from the activities seen in CREATE and collect different pipe sizes to alter and changes its gripping power.
  • Collect at least 2-3 items for your arm to pick up. Example items to use:
    • A crumpled ball of paper
    • Cardboard paper towel roll
    • Roll of masking tape
    • A pencil
    • Rubber band