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

import RPi.GPIO as GPIO
import time
from collections import deque

# GPIO Pins
TRIG_PIN = 23  # GPIO pin connected to the Trigger pin of the sensor
ECHO_PIN = 24  # GPIO pin connected to the Echo pin of the sensor

# Moving Average Filter Parameters
WINDOW_SIZE = 5  # Number of readings for the moving average filter

def setup_gpio():
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(TRIG_PIN, GPIO.OUT)
    GPIO.setup(ECHO_PIN, GPIO.IN)
    GPIO.output(TRIG_PIN, GPIO.LOW)
    time.sleep(2)

def measure_distance():
    """Measure distance using the ultrasonic sensor."""
    # Send a 10µs pulse to trigger the sensor
    GPIO.output(TRIG_PIN, GPIO.HIGH)
    time.sleep(0.00001)
    GPIO.output(TRIG_PIN, GPIO.LOW)
    
    # Measure the time for echo signal
    while GPIO.input(ECHO_PIN) == 0:
        pulse_start = time.time()
    while GPIO.input(ECHO_PIN) == 1:
        pulse_end = time.time()
    
    # Calculate distance in centimeters
    pulse_duration = pulse_end - pulse_start
    distance = pulse_duration * 17150  # Speed of sound (34300 cm/s) / 2
    return round(distance, 2)

def moving_average_filter(data_queue, new_value):
    """Apply a moving average filter to the sensor data."""
    if len(data_queue) >= WINDOW_SIZE:
        data_queue.popleft()
    data_queue.append(new_value)
    return sum(data_queue) / len(data_queue)

def main():
    setup_gpio()
    data_queue = deque(maxlen=WINDOW_SIZE)  # Queue to hold sensor readings for the filter
    
    try:
        while True:
            raw_distance = measure_distance()
            smoothed_distance = moving_average_filter(data_queue, raw_distance)
            
            print(f"Raw Distance: {raw_distance} cm, Smoothed Distance: {smoothed_distance:.2f} cm")
            time.sleep(0.1)  # Delay between readings
    except KeyboardInterrupt:
        print("Measurement stopped by user.")
    finally:
        GPIO.cleanup()

if __name__ == "__main__":
    main()

Explanation:

1. Setup GPIO:

   • Configure the GPIO pins for the trigger and echo of the ultrasonic sensor.
   • Initialize the pins to the appropriate state.

2. Measure Distance:

   • Send a short pulse (10 µs) to the trigger pin.
   • Measure the duration of the echo signal and calculate the distance using the formula Distance = (Pulse Duration * Speed of Sound) / 2.

3. Moving Average Filter:

   • Use a deque with a fixed length (WINDOW_SIZE) to store the last few readings.
   • Compute the average of the values in the deque to smooth the sensor data.

4. Main Loop:

   • Continuously measure the distance, apply the moving average filter, and print the results.
   • Use a try-except block to handle user interruptions gracefully.

5. Cleanup:

   • Ensure the GPIO pins are reset to avoid warnings or errors during subsequent runs.

Notes:

• Dependencies: Install the RPi.GPIO library for Raspberry Pi GPIO control. You can do this via pip install RPi.GPIO.
• Accuracy: Ensure there is no obstruction around the sensor and the target object is within the sensor's range (2 cm to ~300 cm).
• Power Supply: Use a reliable power source for the sensor and microcontroller