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Soda Straw Robot Simulator

Time Required Very Short (≤ 1 day)
Prerequisites You need to work on a computer on which you are allowed to download a new program. Check with the owner of the computer before you proceed.
Material Availability Readily available
Cost Very Low (under $20)
Safety No issues


Robots come in many shapes and sizes. From the Mars Rovers to toy dinosaurs, robots are well-planned machines designed to suit their individual purposes. In this science project, you will test different robot designs with an online simulator made up of dots and lines, much like bendable soda straws. How will each robot design respond to changes in their conditions?


In this science project, students will use an online simulator to test different robotic designs’ stabilities, functionalities, and design goals, given changes in their conditions.


Sara Agee, PhD, Science Buddies

Edited by Justin Spahn, Science Buddies

This science project is based on the Sodaconstructor application:

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Last edit date: 2013-11-16


Robots make many contributions to today's world. There are the famous Mars Rovers (Sojourner, 1997, and Spirit and Opportunity, 2004), 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 Rover
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, so the engineers like to test out their designs 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 science project, you will use an online "soda straw" construction simulator, called Sodaconstructor, 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 the designs have the same dynamics and constraints?

Terms and Concepts

To do this science project, 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
  • Mechanical engineer
  • Software engineer
  • Computer model
  • Simulation
  • Stability
  • Variable
  • Friction
  • Gravity
  • Spring stiffness


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


At this site from NASA, you can read about the Mars Rovers and the exploration of Mars:

If you really like robotics, consider forming a team and competing in BotBall:

Materials and Equipment

  • Computer with internet access
  • Lab notebook
  • Pencil

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Experimental Procedure

  1. Go to sodaplay.com/creators/ed/items/daintywalker. If you need help with downloading, ask the owner of the computer or an adult for help. Be sure you have the computer owner's permission to download this program before you proceed. Visiting the link will take you to a web page with an example of a robot that can be simulated using Sodaconstructor. The Sodaconstructor site requires that you have Java installed on your computer, so click “Launch Daintywalker” and follow all directions until you have downloaded and installed the simulator, and see a new window with the daintywalker robot moving around. This is an example robot design. Each robot is made using dots, which represent connection joints, and lines, which act like springs.
  2. Experiment with the forces acting upon the design by changing the variables of the simulator. Keep careful notes of what you do and what happens in your lab notebook. What happens when you change the variables? Remember to only change one variable at a time! You can reset the robot at any time by closing the window, and clicking once again on “Launch Daintywalker.” Try changing the following variables of the model to test how the model responds to each variable (adapted from SODA, 2007):
    1. Gravity: Turn it up high and models will be squashed by their own weight. Turn it down low and the models will float. You can even turn gravity upside down, causing the robots to fall up!
    2. Friction: Friction slows moving masses (dots). Apply lots of friction (by moving the slider to “sticky”) and it's like moving in molasses. Apply low friction (by moving the slider to “slippy”) and things can move fast, but might wobble out of control.
    3. Spring stiffness: Weak springs (lines) make models floppy. Very stiff springs are strong, but can make the model too jittery. In the Daintywalker program, “loose” springiness corresponds to weak springs, and “tight” springiness corresponds to stiff springs.
  3. 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?
  4. Change to another design file and test the variables in the same way.
    1. You can find other design files by returning to sodaplay.com/creators/ed/items/daintywalker and clicking the “Welcome” tab at the top of the web page (not the robot simulator window). Here you will find many beginner level creations to play with (as well as other simulations, which are in color. Stick to the ones dealing with only dots and lines for the purposes of this science project).
    2. You can also click the “Play” tab at the top of the web page to use robots created by other students who use the simulator.
    3. To open a design file, copy the URL of the design file you want to test, click “File” and then “Open” in the simulator window, and then paste the URL in the box next to “Name,” Alternatively, you can save the design file to the computer and open it from the computer.
    4. How does each design respond? How are each similar to or different from each other? Record your results in your lab notebook.
  5. After testing several designs, identify what makes some designs better robots. Which designs are most stable, despite changes in conditions? Which designs are the most flexible? Which designs are the most dynamic? Can you propose uses for each design based on your results?
  6. Finally, use the simulator to make your own creations!
    1. Make a new file by clicking “File” and then “New” in the simulator window.
    2. Click on the “Construct” button to get started making your creation.
    3. Make sure that you learn how to connect the dots and lines to make shapes and structures. If you do not want a part of your creation to be stationary, make sure that under “Options” the box next to “Fix new masses to the screen” is not checked.
    4. Click “Run” when you are ready to test your creation.
    5. Have fun playing with this at first. Then give yourself a design goal and try to make a robot that can achieve the goal. For example, try to build a robot that has a goal of maintaining its shape no matter what the gravity setting. Come up with your own ideas for robots to build, and then try to build them. Now you’re thinking like a robotics engineer!

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  • 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 "stop" button at the top left so that the simulator stops moving.
    2. Change the design by clicking on any dot (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 that are not as important for the function of the design.
  • 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.

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