// Detects ground and head-level obstacles, alerting via vibration and buzzer
 
// ----- Pin Definitions -----
#define groundTrig 2
#define groundEcho 3
#define headTrig 4
#define headEcho 5
#define groundVibration 6
#define headVibration 7
#define buzzerPin 8
#define waterSensorPin A0
 
// ----- Distance Thresholds (in cm) -----
| const int farThreshold = 100; | // Gentle vibration warning distance |
| --- | --- |
| const int nearThreshold = 40; | // Urgent buzzer alert distance |
const int waterThreshold = 500; // Analog threshold for wet ground detection
 
void setup() {
  pinMode(groundTrig, OUTPUT); pinMode(groundEcho, INPUT);
  pinMode(headTrig, OUTPUT); pinMode(headEcho, INPUT);
  pinMode(groundVibration, OUTPUT);
  pinMode(headVibration, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
 
  Serial.begin(9600);
}
 
void loop() {
  float groundDist = getDistanceCM(groundTrig, groundEcho);
  float headDist = getDistanceCM(headTrig, headEcho);
  int waterLevel = analogRead(waterSensorPin);
 
  handleObstacle(groundDist, groundVibration, "Ground");
  handleObstacle(headDist, headVibration, "Head");
  checkWater(waterLevel);
  checkUrgent(groundDist, headDist);
 
  delay(150); // Short delay between scans for responsive feedback
}
 
// Measures distance using a given ultrasonic sensor pair
float getDistanceCM(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
 
  long duration = pulseIn(echoPin, HIGH, 30000);
  return duration * 0.034 / 2;
}
 
// Activates the corresponding vibration motor if an obstacle is within warning range
void handleObstacle(float distance, int motorPin, String label) {
  if (distance > 0 && distance < farThreshold) {
	digitalWrite(motorPin, HIGH);
	Serial.println(label + " obstacle detected at " + String(distance) + " cm");
  } else {
	digitalWrite(motorPin, LOW);
  }
}
 
// Sounds the buzzer if either sensor detects a very close, urgent obstacle
void checkUrgent(float groundDist, float headDist) {
  if ((groundDist > 0 && groundDist < nearThreshold) ||
  	(headDist > 0 && headDist < nearThreshold)) {
	tone(buzzerPin, 1500);
  } else {
	noTone(buzzerPin);
  }
}
 
// Checks the water sensor and gives a distinct vibration pattern if ground is wet
void checkWater(int level) {
  if (level > waterThreshold) {
	digitalWrite(groundVibration, HIGH);
	delay(100);
	digitalWrite(groundVibration, LOW);
	delay(100);
	digitalWrite(groundVibration, HIGH); // Double-pulse pattern signals "wet ground"
	delay(100);
	digitalWrite(groundVibration, LOW);
  }
}