Assignment 8: Unique Switches

This is my body-based switch, which turns on when the ultrasonic sensor detects a barrier within its range.

Assignment Brief

• Create an unusual switch that doesn’t require the use of your hands
• This should be a switch that opens and closes a circuit
• You should use digitalRead in the Arduino to get the state of your switch and do something based on that information

Conceptualisation

The idea for this project emerged from my will to create something interactive, something that responds to input and only works when someone makes the active choice to be continually using it. I was considering a domino effect game where an initial topple or roll of a marble caused a chain reaction that connected the contact points. However, I decided to take advantage of the equipment provided, instead, and use the motion sensor. By choosing the motion sensor for this experience, I hoped to make it a more interactive and sustainable, as people are able to enjoy an extent of interactivity without needing to reset the entire set-up every time it is going to be used.

Process

1. Component Selection: I gathered an Arduino board, an ultrasonic sensor (HC-SR04), LEDs, resistors, and jumper wires

2. Circuit Assembly: I carefully wired the ultrasonic sensor to the Arduino, ensuring proper connections for power, ground, trigger, and echo pins. I then connected the LEDs to digital pins on the Arduino through a current-limiting resistor

3. Code Development: I wrote Arduino code to control the ultrasonic sensor and LED. The code sends out ultrasonic pulses, measures the time for the echo to return, calculates the distance, and turns the LED on or off based on that distance

4. Calibration: I experimented with different distance thresholds to determine the optimal range for triggering the LED. This involved repeated testing and code adjustments

Challenges

1. Sensor Accuracy: The sensor is limited by the hardware it is made from. Signals may be deflected and so sometimes the sensor won’t receive the signals back. Hence, it only works against flat surfaces

2. False Triggers: Early versions of the system would sometimes trigger in the wrong order due to mis-labelling and mis-wiring. I addressed this by adjusting the sensor’s sensitivity and implementing a minimum detection time to filter out momentary false positives

Potential Improvements

1. Multiple Sensors: Incorporating additional ultrasonic sensors could create a more comprehensive detection field, allowing for directional awareness

2. Variable LED Response: Instead of a simple on/off state, the LED brightness could vary based on the detected distance, creating a more nuanced interaction.

3. Energy Efficiency: Exploring low-power modes and more efficient components could extend battery life for portable applications.

Source Code

const int echo = 13;
const int trig = 12;

int duration = 0;
int distance = 0;

void setup() 
{
  // put your setup code here, to run once:
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  Serial.begin(9600);
}

void loop() 
{
  // put your main code here, to run repeatedly:
  digitalWrite(trig, HIGH);
  delayMicroseconds(1000);
  digitalWrite(trig, LOW);

  duration = pulseIn(echo, HIGH);
  distance = (duration/2) / 28.5;
  Serial.println(distance);
}