School Project: Sensor Stick for the Blind

A sensor stick for the blind helps visually impaired individuals detect obstacles using ultrasonic sensors and vibrations. This simple yet impactful project is a great way to explore physics, electronics, and engineering concepts.

🔧 Requirements (Materials Needed)

Electronics:

1. Arduino Uno / Nano (for processing signals)
2. Ultrasonic Sensor (HC-SR04) (to detect obstacles)
3. Buzzer / Vibrating Motor (for alerting the user)
4. Battery Pack (9V or Rechargeable Li-ion)
5. Jumper Wires & Breadboard
6. Resistors (330Ω, 1KΩ as needed)
7. Switch (for turning the device on/off)

Mechanical:

8. PVC Pipe / Wooden Stick (to act as the walking stick)
9. Casing (Plastic Box / 3D Printed Holder) (for electronics protection)
10. Electrical Tape & Glue Gun

🛠️ Steps to Build the Sensor Stick

Step 1: Assemble the Circuit

1. Connect the Ultrasonic Sensor (HC-SR04) to Arduino
   • VCC → 5V (Arduino)
   • GND → GND (Arduino)
   • Trig → Digital Pin 9
   • Echo → Digital Pin 10
2. Connect the Buzzer / Vibrating Motor
   • One end to Digital Pin 6
   • The other end to GND
3. Connect the Battery Pack
   • Positive terminal to Vin (Arduino)
   • Negative terminal to GND
4. Attach the Switch to the battery circuit for easy ON/OFF control.

Step 2: Code the Arduino

Upload the following code to the Arduino using the Arduino IDE:

#define trigPin 9
#define echoPin 10
#define buzzer 6

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2; // Convert to cm

  Serial.println(distance);

  if (distance < 50) {  // If object is within 50 cm
    digitalWrite(buzzer, HIGH);  
  } else {
    digitalWrite(buzzer, LOW);
  }

  delay(100);
}

Step 3: Attach Components to the Stick

1. Fix the ultrasonic sensor to the front of the walking stick.
2. Secure the Arduino and battery pack in a plastic casing attached to the stick.
3. Use tape/glue to ensure the wiring is secure and protected.

Step 4: Test the System

• Turn on the sensor stick.
• Move towards an obstacle—if the sensor detects an object within 50 cm, the buzzer/motor should activate.
• Adjust the distance threshold in the code if needed.

🎯 Project Benefits & Learning Outcomes

✔️ Real-world application for accessibility solutions
✔️ Understanding of ultrasonic sensors & Arduino programming
✔️ Introduction to assistive technology & innovation

Here’s a simple wiring diagram to follow when connecting your components:

Connections:

⚡ Troubleshooting Tips

If your project isn’t working as expected, check the following:

1️⃣ Ultrasonic Sensor Not Detecting Objects?

✔️ Ensure correct wiring (VCC to 5V, GND to GND, Trig to D9, Echo to D10).
✔️ Check if the Trig pin is sending signals (Use Serial Monitor in Arduino IDE to print distance values).
✔️ Ensure nothing is blocking the sensor’s field of view.

2️⃣ Buzzer Not Buzzing / Vibrator Not Working?

✔️ Check if the correct digital pin (D6) is used.
✔️ Try connecting the buzzer/motor directly to 5V—if it works, the issue is in the code.
✔️ If using a vibrating motor, ensure it has the correct voltage & resistor to avoid overloading.

3️⃣ Arduino Not Turning On?

✔️ Check battery voltage (should be above 7V for Vin).
✔️ Ensure the switch is turned ON and the battery is properly connected.