Project 2 - Measuring the distance of an object using ultrasonic sensor and also smoothen the sensor data using moving average filter

Components Needed:

• 1 Arduino board
• 1 Ultrasonic Distance Sensor (28015 Ping)
• Breadboard and jumper wires

Working Principle:

• The sensor emits a sound wave at a frequency above human hearing (ultrasonic) and measures the time it takes for the echo to return after bouncing off an object.
• The distance is calculated using the formula: $$\text{Distance} = \frac{\text{Time} \times \text{Speed of Sound}}{2}$$Distance=2Time×Speed of Sound​
• The factor of 2 accounts for the round trip of the sound wave (to the object and back).

Connections for the 28015 Ping Sensor:

• VCC to 5V on Arduino.
• GND to Ground on Arduino.
• SIG (Signal Pin) to any digital I/O pin (e.g., pin 7).

Moving Average Filter:

• The moving average filter smoothens the data by averaging a certain number of the most recent data points. This reduces the effect of outliers or sudden changes in the sensor readings.

Code:

// Define pin numbers

const int pingPin = 7; // Pin connected to the Ping sensor's SIG pin

// Parameters for Moving Average Filter

const int numReadings = 10;

int readings[numReadings]; // Array to hold sensor readings

int readIndex = 0; // Index for current reading

int total = 0; // Total of readings

int average = 0; // The average value

void setup() {

Serial.begin(9600); // Start serial communication

pinMode(pingPin, OUTPUT);

// Initialize all readings to 0

for (int i = 0; i < numReadings; i++) {

readings[i] = 0;

}

}

void loop() {

long duration, inches;

// Trigger the Ping sensor

pinMode(pingPin, OUTPUT);

digitalWrite(pingPin, LOW);

delayMicroseconds(2);

digitalWrite(pingPin, HIGH);

delayMicroseconds(5);

digitalWrite(pingPin, LOW);

// Read the echo

pinMode(pingPin, INPUT);

duration = pulseIn(pingPin, HIGH);

// Convert time into distance in inches

inches = microsecondsToInches(duration);

// Update the moving average filter

total = total - readings[readIndex]; // Subtract the oldest reading

readings[readIndex] = inches; // Store the new reading

total = total + readings[readIndex]; // Add the new reading to the total

readIndex = (readIndex + 1) % numReadings;// Advance to the next position

average = total / numReadings; // Calculate the average

// Print the results to the Serial Monitor

Serial.print("Distance: ");

Serial.print(average);

Serial.println(" inches");

delay(100); // Delay for readability and stability

}

// Convert the duration to distance in inches

long microsecondsToInches(long microseconds) {

return microseconds / 74 / 2;

}