Robotics on a Budget: Building Simple Machines

Learning Objectives

After completing these projects, students will be able to:

• Build a basic moving robot using recycled materials
• Understand how simple circuits work
• Write basic code to control a robot’s behaviour
• Apply problem-solving skills to engineering challenges
• Explain how sensors can be used to interact with the environment

Safety First!

Before we begin, let’s review some important safety rules:

• Always wear safety glasses when using tools
• Have adult supervision when using hot glue guns
• Be careful with scissors and sharp edges
• Keep your workspace clean and organized
• Handle electrical components with care
• If something doesn’t look right, ask for help!

Project 1: The Walker Bot (90 minutes)

Our first project is a simple walking robot that teaches us about motors, circuits, and mechanical movement.

What You’ll Need

For each robot:

Building Materials

• 1 clean 2L plastic bottle
• Thick cardboard (about A4 size)
• Clear tape
• 4 rubber bands
• 4 cable ties

Electronics

• 2 small DC motors (3-6V, from old toys or purchased)
• 1 battery holder (for 4 AA batteries)
• 4 AA batteries
• 1 simple slide switch
• Red and black wire
• Electrical tape

Tools (to be shared)

• Safety scissors
• Hot glue gun and glue sticks (teacher supervised)
• Ruler
• Marker
• Safety glasses

Building Your Robot

Step 1: Prepare the Bottle (15 minutes)

1. Clean your bottle and remove all labels
2. Put on safety glasses
3. Carefully measure 8cm up from the bottom
4. Draw a line around the bottle
5. Cut along the line with scissors
6. Sand any sharp edges (ask your teacher for help)

Step 2: Add the Motors (20 minutes)

1. Find the middle of your bottle (about 3cm up from cut edge)
2. Mark two spots on opposite sides
3. Create small holes for the motors:
   • Either cut small X shapes with scissors
   • Or ask your teacher to help melt holes
4. Push motors through from the inside
5. Secure with cable ties
6. Add a small amount of hot glue to hold them steady

Step 3: Make the Legs (20 minutes)

1. Draw two circles on cardboard (about 8cm across)
2. Cut them out carefully
3. Make a small hole in the center of each
4. Push onto motor shafts
5. Secure with a drop of hot glue Important: Make sure legs are exactly opposite each other!

Step 4: Wire It Up (35 minutes)

1. Connect your circuit:
   • Red wire from battery pack to switch
   • Switch to both motor red wires
   • Black wires from motors to battery pack black wire
2. Test your connections
3. Add batteries
4. Try it out!

Testing Your Robot

Place your robot on a flat surface and turn it on. It should walk forward in a fairly straight line. If not, check:

1. Are the legs lined up properly?
2. Are both motors turning?
3. Is your robot balanced?

Project 2: Adding a Brain (120 minutes)

Now let’s make our robot smarter by adding a light sensor! This will teach us about programming and how robots can sense their environment.

New Materials Needed

• Arduino Uno board
• Light sensor (LDR)
• 10kΩ resistor (brown-black-orange)
• LED
• 220Ω resistor (red-red-brown)
• 5 jumper wires
• Small breadboard
• USB cable

Building the Circuit

1. Connect your components:
   • LDR to Arduino A0 and ground
   • LED to Arduino pin 13 (with resistor)
   • Follow the diagram provided by your teacher

Programming Your Robot

Before we start programming, make sure you have:

• Arduino IDE installed on your computer
• USB cable ready to connect Arduino
• All circuit components connected correctly

Getting Ready to Program:

1. Open the Arduino IDE on your computer
2. Click File > New Sketch
3. Delete any existing code in the window (there might be some basic code already there)
4. Copy and paste this entire code block into your empty sketch:

// Define our pins
const int sensorPin = A0;  // Light sensor
const int ledPin = 13;     // LED light

// Setup our pins
void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);  // Start communication
}

// Main program
void loop() {
  // Read the light level
  int lightLevel = analogRead(sensorPin);
  
  // Print it so we can see
  Serial.print("Light level: ");
  Serial.println(lightLevel);
  
  // If it's dark, turn on LED
  if (lightLevel < 500) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
  
  // Wait a moment
  delay(100);
}

Uploading Your Code:

1. Click the “Verify” button (checkmark) to check for errors
2. Connect your Arduino to your computer using the USB cable
3. In the Arduino IDE, select:
   • Tools > Board > Arduino Uno
   • Tools > Port > (select the port that appeared when you plugged in Arduino)
4. Click the “Upload” button (arrow) to send the code to your Arduino
5. Wait for the message “Upload complete” at the bottom of the window

Testing Your Code:

1. Open the Serial Monitor (magnifying glass icon in top right)
2. You should see numbers appearing – these are your light readings
3. Cover the light sensor with your hand – the numbers should go down
4. When it’s dark enough, the LED should turn on

Understanding the Code

Let’s break down what each part does:

1. First, we tell Arduino which pins we’re using
2. In setup(), we get things ready
3. In loop(), we:
   • Read the sensor
   • Print the reading
   • Decide if it’s dark or light
   • Turn LED on or off
   • Wait a bit before checking again

Troubleshooting Guide

If Your Robot Won’t Walk

1. Check batteries
2. Look for loose wires
3. Make sure legs are firmly attached
4. Test motors individually

If Your Sensor Doesn’t Work

1. Check all connections
2. Verify Arduino is powered
3. Make sure code is uploaded
4. Test with different light levels

Extension Activities

Ready for more challenges? Try:

1. Add a second sensor
2. Make your robot avoid obstacles
3. Create different leg designs
4. Add blinking lights
5. Make your robot respond to sound

Links to Curriculum

This project helps develop skills in:

• Science: Electrical circuits, energy transformation
• Technology: Programming, system design
• Engineering: Mechanical systems, problem-solving
• Mathematics: Measurement, geometry

Assessment Ideas

Students can demonstrate learning through:

1. Design documentation
2. Working robot
3. Code explanation
4. Problem-solving log
5. Class presentation

Resources

• Digital Technologies Hub
• CSIRO STEM Resources

Remember: The best robot isn’t always the most complex – it’s the one that does its job reliably and teaches you something new!