Goal of the Challenge:
Work in teams to build a vibrating brush robot using a motor, a brush, and a few other materials.
Your goal: A racing robot that completes a track in record time!
Details:
- Theme: Electronics, Locomotion
- Duration: 1h – 1h30
- Teams: Groups of up to 4 people
Infobox
Take Off is a scientific science game show where 12 smart young adults tackle challenging tasks. In each episode, one contestant is eliminated. In the grand finale, the winner takes home a prize of €10,000.
The show airs on RTL, RTL Play, and YouTube. On Instagram and TikTok, you can find short, entertaining behind-the-scenes videos featuring the contestants and hosts.
Materials List:
For each team (max. 4 persons per team), you will need:
• Motor set with cables, switch, and battery holder (e.g., an 8-set available online for approx. €11; available [here])
• 2 AA batteries
• A hand brush
• Terminal block (Domino connector) or a cork
• Screwdriver
• Fastening materials (e.g., double-sided tape, rubber bands, cable ties, insulating tape, or paper tape)
• Scissors
• Weights (e.g., coins, nuts)
• Books to build a race track
• Optional materials for creative solutions: hot glue, pipe cleaners, kebab sticks, switches, crocodile clips, saw
Preparation:
- Form Teams: Divide the class into teams of no more than four people.
- Distribute Materials: Ensure each team receives the same set of materials.
- Build a Race Track: Use books to easily set up a small test and race track.
- In the video, we show you what a broom bot can look like.
Challenge Question:
How do you build a broom robot that moves as quickly as possible?
Two Hints for the Teams:
• The motor must be securely mounted on the brush.
• Attach something asymmetrical to the motor axis so that the motor vibrates.
Hypothesis:
Before starting, teams should spend a few minutes discussing their design plans and sharing ideas. Everyone in the team should contribute.
Experiment: Building the broom Robot
Determine a time ( 30–45 minutes) during which the students can build freely. They should work through the following steps independently:
1. Build the Circuit:
The first thing they need to find out is how to build a simple circuit: from the positive terminal of the battery, through the switch to the motor, and back to the negative terminal of the battery.
Note: If the students have no experience with circuits, explain that current always flows in a loop and that the batteries must never be short-circuited.
2. Attach the Imbalance:
As mentioned earlier, students should attach a terminal block or another asymmetrical object to the motor axis to generate vibration.
3. Mount the Motor and Battery Holder:
Use double-sided tape, cable ties, and/or rubber bands to attach the motor and battery holder securely to the brush.
4. Test and Optimize:
Teams must then test their constructions and optimize for speed. They can experiment with the position of the motor and the imbalance, trim different brush bristles, or adjust the gravity point to improve the robot's movement.
Competition: Who Has the Fastest Robot?
After the building and testing phase, the big moment arrives:
- Launch the teams’ broom robots one after the other on the same race track and measure the time.
- The fastest team wins!
Discussion and Optimization:
After the competition, discuss with the class:
• Why was the winning robot so fast?
• What modifications could improve the other robots?
Film the robots using the slow motion function on a smartphone and try to explain the working mechanism (see paragraph: Physics of the Broom Robot) .
If time permits, teams can further optimize their robots and compete in a second round.
Everyday Applications: Where Do We Find the Broom Robot’s Technology in Daily Life?
The principle behind the broom robot is also used in mobile phones. Vibrations in phones are generated by a small motor with an asymmetrically attached mass.
This phenomenon also occurs in washing machines when laundry is unevenly distributed inside the drum. The imbalance causes the machine to vibrate or even "jump" during the spin cycle.
Physics of the Broom Robot
The motor's imbalance creates vibrations, which cause the bristles of the brush to bend and straighten alternately. As the bristles bend, they store elastic energy. Once the motor’s rotation releases the pressure, the bristles spring back and slightly "catapult" the entire vehicle forward.
The position of the motor affects the robot’s center of gravity and thus its direction of movement. The weight and the center of gravity of the imbalance influence the strength of the vibrations. Additionally, the surface texture and friction impact the movement.
Since Tim's broom robot moves rather slowly, the explained mechanism can be clearly observed.
Author: Joseph Rodesch (FNR)
Editor: Lucie Zeches (FNR)
Die Ausarbeitung dieser Rubrik wurde von science.lu in Kooperation mit dem Script (Service de Coordination de la Recherche et de l´Innovation pédagogiques et technologiques) durchgeführt.
