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Project Summary

Difficulty	4  –  8
Time required	Very Short (a day or less)
Prerequisites	None
Material Availability	Readily available
Cost	Very Low (under $20)
Safety	No issues

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Abstract

Objective

In this experiment you will use a simulator to test different robotic designs for stability.

Introduction

Robots may seem like a thing of the future, but robots make many contributions to today's world. There is the famous Mars Rover which collected samples and photographs on the planet Mars for scientists at NASA. There are underwater robots that help oceanographers explore deep sea vents. Robotic machines are very important in modern manufacturing. And there are, of course, some very cool toy robots that talk, sing, and even dance.

The Mars Rovers have gone where no man has gone before! (NASA, 2003)

Each robot was designed for a purpose, to do a certain set of tasks. A robot has to be carefully planned with this purpose in mind by a mechanical engineer. The engineer will make sure that the robot is built such that its structure allows it to move in a way for it to complete its task. Then a software engineer will program the robot with the set of instructions it needs to perform the task.

Building a robot is a very labor intensive process, and so the engineers like to test out their design as much as possible before they commit to building it. One way to test a design is to make a computer model. Some advanced computer models allow you to run a simulation so that you can "see" how the robot will behave in certain conditions before you even build it. The engineer can then incorporate the information from the simulation to improve the robot design.

In this experiment you will use an online soda straw construction simulator to investigate different robotic designs. In the simulator, you can test different robot designs for stability while changing the variables for friction, gravity, or spring stiffness. What will happen to the design? Will all designs have the same dynamics and constraints?

Terms, Concepts and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

• robot
• design
• simulator
• complexity
• friction
• gravity
• spring stiffness

Questions

• How do robots move?
• How are robots designed?
• Are complex designs better than simple designs?

Bibliography

• This project is based on the sodaconstructor Java application:
  Soda, 2007. "sodaconstructor," London, UK: Soda Creative Ltd. [accessed February 10, 2007] http://www.sodaplay.com/constructor
• This site from NASA offers a wealth of information about robotics:
  NASA, 2007a. "Robotics Curriculum Clearinghouse - Lesson Plans and Educational Resources," National Aeronautics and Space Administration (NASA). [accessed February 10, 2007] http://robotics.nasa.gov/rcc/
• At this site from NASA you can read about the Mars Rovers and the exploration of Mars:
  NASA, 2007b. "Mars Exploration Rover Mission," California Institute of Technology: Jet Propulsion Laboratory, National Aeronautics and Space Administration (NASA). [accessed February 10, 2007] http://marsrovers.nasa.gov/home/
• If you really like robotics, consider forming a team and compete in BotBall:
  Botball.org, 2007 "Botball Homepage," Norman, OK: KISS Institute for Practical Robotics. [accessed February 10, 2007] http://www.botball.org/

Materials and Equipment

• Internet
• lab notebook
• pencil

Experimental Procedure

1. Go to http://www.sodaplay.com/constructor. (The sodaconstructor site requires that you have java virtual machine (vm) installed on your computer.) Click the "click here to play" button. A new window will appear with a model of a walking soda robot. You can also choose your own model by clicking on the "file" button, but I recommend starting this project with the default file.
2. Change the forces acting upon the design by changing the variables of the simulator. Try changing these variables of the model to test how the model responds to each variable (adapted from SODA, 2007):
   • gravity (g) - Turn it up high and models are squashed by their own weight. Turn it down low and things float. You can even turn gravity upside down using the popup menu.
   • friction (f) - Friction slows moving masses. Apply lots of friction and it's like moving in molasses. Apply low friction and things can move fast but might wobble out of control.
   • spring stiffness (k) - Weak springs make models floppy. Very stiff springs are strong, but can make the model too jittery.

3. What happens when you change the variables? Keep careful notes of what you do and what happens in a laboratory notebook.
4. Analyze your results. Have you identified a variable that is important to the function of this design? What are the limits of this variable that allow the design to move and function? How much change, or flexibility, is there in the design?
5. Change to another design file and test the variables in the same way. How does this design respond? Is it similar or different? Record your results in your lab notebook.
6. After testing several designs, identify what makes some designs more robust than others. Which designs are most stabile to change? Which designs are the most flexible? Which designs are the most dynamic? Can you propose uses for each design based upon your results?

Variations

• In sodaconstructor, you can also change the design of the model and see how the movement of the design changes. Just follow these steps:
  1. Click on the drop down menu and change from "simulator" to "construct" so that the simulator stops moving.
  2. Change the design by clicking on any point (mass) in the drawing and moving it around. This will also change the length of the adjacent segments.
  3. Add new points and segments by clicking elsewhere in the edit screen. Each click will generate one new mass with an adjoining segment.
  4. Continue doing this to identify regions that are very important for the design to function, and those which are not as important for the function of the design.
• Can you make your own design? You can start from scratch, or use a file as a starting point and make modifications. How well does your design move? How stabile is it? If you create a good design, you can even submit it (with your parents permission) to the sodazoo.
• You can make a mock-up of these designs using soda straws and flexible connectors. Cut drinking straws to length using scissors. To make your joint push a small amount of clay into the end of the straw. Insert a small length of pipe-cleaner into the clay and attach to the next piece to form a flexible joint.

• For more science project ideas in this area of science, see Mechanical Engineering Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Sources

This project is based on the sodaconstructor application:
Soda, 2007. "sodaconstructor," London, UK: Soda Creative Ltd. [accessed February 10, 2007] http://www.sodaplay.com/constructor

Last edit date: 2007-04-03 23:00:00

Career Focus

If you like this project, you might enjoy exploring careers in Mechanical Engineering.

	Mechanical Engineer Mechanical engineers are part of your everyday life, designing the spoon you used to eat your breakfast, your breakfast's packaging, the flip-top cap on your toothpaste tube, the zipper on your jacket, the car, bike, or bus you took to school, the chair you sat in, the door handle you grasped and the hinges it opened on, and the ballpoint pen you used to take your test. Virtually every object that you see around you has passed through the hands of a mechanical engineer. Consequently, their skills are in demand to design millions of different products in almost every type of industry.			Mechanical Engineering Technician You use mechanical devices every day—to zip and snap your clothing, open doors, refrigerate and cook your food, get clean water, heat your home, play music, surf the Internet, travel around, and even to brush your teeth. Virtually every object that you see around has been mechanically engineered or designed at some point, requiring the skills of mechanical engineering technicians to create drawings of the product, or to build and test models of the product to find the best design.
	Precision Instrument and Equipment Repairer One of the basic truths in the universe is that objects tend to go from a state of higher organization to a state of lower organization over time. In other words, things break down, and when those things are precision instruments or equipment, they require the services of very specialized technicians to restore them to their working order. Precision instrument or equipment technicians often combine a love of music, medicine, electronics, or antiques with delicate mechanical repair work.

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