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Racing Bristlebots: On Your Mark. Get Set. Go!

Abstract

Have you ever wanted to build your very own robot from scratch? Bristlebots are a cheap, easy, and fun-to-build robot made from the head of a toothbrush, a battery, and a small motor. Once completed, they buzz along the top of a table like bugs. How can you make a bristlebot go faster? In this project, you will build bristlebots from two different types of toothbrushes, and race them against each other to find out.

Summary

Areas of Science
Difficulty
 
Time Required
Very Short (≤ 1 day)
Prerequisites
None
Material Availability
A kit is available for your convenience from our partner Home Science Tools.
Cost
Low ($20 - $50)
Safety
Adult supervision is required when cutting the head off a toothbrush.
Credits

Ben Finio, PhD, Science Buddies

Recommended Project Supplies

Get the right supplies — selected and tested to work with this project.

View Kit

Objective

Build one bristlebot with straight bristles and one with slanted bristles, and race them to see which is faster.

Introduction

Have you ever wanted to build your own robot? What about tiny robots that you could race against each other? In this science project, you will build and race bristlebots, tiny robots built on the head of a toothbrush, like the ones shown in Figure 1.

Two bristlebots side-by-side
Figure 1. Two bristlebots racing against each other.

The bristlebot uses a small electric motor to move. In order to power the motor, the robot also needs a battery. When you connect the battery to the motor, you complete an electrical circuit. This makes a tiny weight inside the motor spin, causing it to vibrate. When the motor vibrates, it causes the robot to shake and buzz along the tabletop. This is the same type of motor that makes video game controllers and cell phones vibrate.

In this science project, you will build two different bristlebots: one with slanted toothbrush bristles, and one with straight bristles. Then you will race them against each other to see which one is faster!

Terms and Concepts

Questions

Bibliography

This project is based on the following post by Evil Mad Scientist Laboratories:

If you want to learn more about some of the concepts in this project, like circuits and vibrational motion, check out these references:

Materials and Equipment Buy Kit

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Experimental Procedure

Building Your Bristlebots

  1. Get an adult to use strong scissors or pliers to help you cut the heads off two toothbrushes, one with slanted bristles and one with straight bristles.
  2. Follow the instructions in the video or the step-by-step instructions and pictures below to build two bristlebots. Note: be gentle with the motor wires. They are thin and can rip if you are not careful. You can apply a dab of hot glue at the base of the wires to reinforce them.
How to Make a Bristlebot

Step-by-Step Instructions

  1. Stick foam tape to top of toothbrush.
    Stick foam tape to top of toothbrush.
    Figure 2. Stick foam tape to top of toothbrush.
  2. Peel backing off foam tape.
    Peel backing off foam tape.
    Figure 3. Peel backing off foam tape.
  3. Pull pieces of insulation off ends of battery wires.
    Pull pieces of insulation off ends of battery wires.
    Figure 4. Pull pieces of insulation off ends of battery wires.
  4. Battery with insulation pieces removed.
    Battery with insulation pieces removed.
    Figure 5. Battery with insulation pieces removed.
  5. Attach battery to foam tape.
    Attach battery to foam tape.
    Figure 6. Attach battery to foam tape.
  6. Battery attached to toothbrush.
    Battery attached to toothbrush.
    Figure 7. Battery attached to toothbrush.
  7. Peel paper backing off motor.
    Peel paper backing off motor.
    Figure 8. Peel paper backing off motor.
  8. Attach motor to toothbrush.
    Attach motor to toothbrush.
    Figure 9. Attach motor to toothbrush.
  9. Battery and motor attached to toothbrush.
    Battery and motor attached to toothbrush.
    Figure 10. Battery and motor attached to toothbrush.
  10. Twist together red wires.
    Twist together red wires.
    Figure 11. Twist together red wires.
  11. Twist together black wires.
    Twist together black wires.
    Figure 12. Twist together black wires.
  12. Your bristlebot should now vibrate.
    Your bristlebot should now vibrate.
    Figure 13. Your bristlebot should now vibrate.
  13. Do not let red and black wires touch. This will create a short circuit, quickly drain the battery, and prevent the motor from vibrating.
    Do not let red and black wires touch. This will create a short circuit, quickly drain the battery, and prevent the motor from vibrating.
    Figure 14. Do not let red and black wires touch. This will create a short circuit, quickly drain the battery, and prevent the motor from vibrating.
  14. If your robot stops moving suddenly, make sure the wires did not come loose. Re-twist them tightly if necessary.
    If your robot stops moving suddenly, make sure the wires did not come loose. Re-twist them tightly if necessary.
    Figure 15. If your robot stops moving suddenly, make sure the wires did not come loose. Re-twist them tightly if necessary.
  15. If your robot falls over, make sure the battery and motor are centered on the toothbrush. You can also let it run for 5-10 minutes to drain the battery and it will slow down.
    If your robot falls over, make sure the battery and motor are centered on the toothbrush. You can also let it run for 5-10 minutes to drain the battery and it will slow down.
    Figure 16. If your robot falls over, make sure the battery and motor are centered on the toothbrush. You can also let it run for 5-10 minutes to drain the battery and it will slow down.
  16. Optional: decorate your bristlebot!
    Optional: decorate your bristlebot!
    Figure 17. Optional: decorate your bristlebot!

Troubleshooting

  1. Do not let the exposed metal parts of the red and black wires touch each other directly. This will create a short circuit and drain the battery very quickly, and will prevent the motor from vibrating.
  2. If your robot stops moving suddenly, check to make sure that one or both sets of wires did not come loose. This will create an open circuit and prevent the motor from vibrating. Tightly twist the wires back together if this happens.
  3. If your robot falls over a lot, make sure the motor and battery are centered on top of the toothbrush. You can also let the robot run continuously for 5–10 minutes, and it will slow down slightly as the battery begins to drain.
  4. To turn your bristlebot off, just untwist one set of wires (you do not need to disconnect both). Make sure you turn your robot off when not in use to conserve battery power.

Racing Your Bristlebots

  1. Make a racetrack for your bristlebots by setting up three large books on a smooth, flat surface, as shown in Figure 18. This creates two "chutes" that will force your bristlebots to go straight.
Three textbooks are evenly spaced apart to create two paths that bristlebots can move along
Figure 18. Racing chutes for bristlebots, made using three large books.
  1. Get ready to race your bristlebots! Reconnect the wires for each robot to turn them back on.
  2. Test your bristlebots in your racing chutes. If the chutes are too narrow, your bristlebots might get stuck. If they are too wide, they might spin around or fall over. Adjust the width of the chutes, if necessary.
  3. Pick up your bristlebots and place them side by side in your racing chutes.
  4. Let go of both bristlebots at the same time. Watch closely to see which one makes it to the other end of the chute first.
  5. If one robot goes backwards, flip it around and start over.
  6. Record the winner of the race in your lab notebook.
  7. Repeat the race four more times, for a total of five trials. Make sure you record your results in your lab notebook.
  8. Optional: Use a stopwatch to record how long it takes each bristlebot to go down the chute. Have a volunteer help if it is too difficult to use a stopwatch and control both bristlebots at the same time.
  9. Analyze your results.
    1. Does one bristlebot consistently win the race?
    2. How do your results compare to your prediction about which type of bristlebot would be faster?

Troubleshooting

For troubleshooting tips, please read our FAQ: Racing Bristlebots: On Your Mark. Get Set. Go!.

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Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Variations

  • Try building more bristlebots with even more types of toothbrushes. Which toothbrush head works the best?
  • If you would like to build a larger robot that works on the same principle as the bristlebot (vibrational motion), check out the Science Buddies project Art Bot: Build a Wobbly Robot That Creates Art. The electronic parts required to build an Art Bot are already included in your Basic Vibrobot kit from Science Buddies.
  • If you would like to try a more advanced project, you can build a light-following bristlebot in the Build a Light-Tracking Bristlebot project.
  • Instead of using a chute, make a circular "arena" for your bristlebots to let them move around freely. Set up a video camera directly above the arena, looking down, and use it to record the bristlebot's motion. Then, analyze the video with a computer and make plots of the path each bristlebot follows. Do the paths seem totally random, or can you identify any patterns? For example, do certain bristlebots tend to always turn in one direction?
  • Make a "maze" for your bristlebots and time how long it takes different designs to find their way out of the maze.

Explore More!

Looking for more robot fun? Explore the World of Robotics with This Suite of Projects!

Frequently Asked Questions (FAQ)

If you are having trouble with this project, please read the FAQ below. You may find the answer to your question.
Q: Why will my bristlebot not go straight?
A: A bristlebot's motion is random, meaning that it has no steering. It is very difficult to build a bristlebot that will go perfectly straight on its own. This is why the instructions recommend making a chute to guide the bristlebots on a straight path.
Q: Why does my bristlebot keep falling over?
A: If your bristlebot falls over frequently, there is a chance that your motor and battery are off-center. Try adjusting the motor and battery to make sure they are centered on the toothbrush head. Your bristlebot will also move faster and be more likely to fall over for the first 5–10 minutes of use. As the battery drains, the robot will slow down and will not fall over as much. If you cannot get the robot to stop falling over even after adjusting the motor and battery, let it run continuously for 5–10 minutes and then try again.
Q: Why does my bristlebot suddenly stop moving?
A: If your bristlebot abruptly stops moving, two of the wires you twisted together probably came loose. Constant vibrations can cause the wires to wiggle and gradually come apart. Check to make sure the wires from the motor and battery are tightly twisted together.
Q: Why can I not measure a speed difference between my two bristlebots?
A: Make sure you are using two completely different types of toothbrush heads, one with straight bristles and one with slanted bristles. If you are using two similar toothbrush heads, even if they are not identical, the bristlebots might move at about the same speed.
Q: How long will my bristlebots' batteries last?
A: Your bristlebots' motors use a lot of electricity. The tiny coin cell batteries that come with your bristlebots were not designed to supply a lot of electricity for long periods of time. Each battery should last for about one hour, but the robots may start to slow down after 30–45 minutes of continuous use.

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MLA Style

Science Buddies Staff. "Racing Bristlebots: On Your Mark. Get Set. Go!" Science Buddies, 15 Jan. 2022, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Robotics_p010/robotics/racing-bristlebots?from=Blog. Accessed 2 July 2022.

APA Style

Science Buddies Staff. (2022, January 15). Racing Bristlebots: On Your Mark. Get Set. Go! Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Robotics_p010/robotics/racing-bristlebots?from=Blog


Last edit date: 2022-01-15
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