Team THUNDERBOLTZ:

•

•

•

Published September 15, 2026

RayBot

An AI-powered water-quality monitoring rover using biomimetic sine-wave propulsion for efficient, autonomous aquatic exploration.

AdvancedWork in progress41

Things used in this project

Hardware components

Arduino UNO Q

M5Stack ESP32 Camera Module Development Board

TinyCircuits TinyShield GPS

Atlas Scientific Gravity™ Analog pH Sensor

Turbidity Sensor, Phototransistor Output

Adafruit Waterproof DS18B20 Digital temperature sensor

lipo battery

Cytron Technologies Maker Drive: Simplifying H-Bridge Motor Driver for Beginner

Software apps and online services

Arduino App Lab

Edge Impulse Studio

Hand tools and fabrication machines

Wire Cutter / Stripper, 5.25 " Overall Length

Soldering iron (generic)

3D Printer (generic)

Story

RAYBOT

is an AI-powered autonomous water-quality monitoring rover inspired by the natural movement of aquatic animals. We developed it to address a simple but important problem:

monitoring water quality across a large water body is difficult, time-consuming, and often requires human intervention.

Traditional monitoring generally depends on collecting water samples at selected locations and testing them separately. This can miss changes occurring between sampling points. RAYBOT is designed to bring sensing, mobility, vision, and intelligence together in a single platform.

How RAYBOT works

RAYBOT uses biomimetic sine-wave propulsion instead of conventional propellers. Multiple servo-driven fin sections create a phase-shifted traveling wave, allowing the flexible fin to generate an undulatory swimming motion inspired by fish and rays.

The rover carries multiple water-quality sensors to measure:

pH – acidity/alkalinity
TDS – total dissolved solids
Turbidity – water clarity
Temperature – water temperature

An ESP-CAM provides visual monitoring, while GPS enables location tracking. The Arduino UNO Q acts as the onboard processing platform, combining sensor information and supporting edge-AI processing for real-time analysis and decision-making.

The overall workflow is:

Sense → Process → Analyze → Locate → Monitor → Act

Our goal is to develop RAYBOT into a platform capable of continuously exploring water bodies, identifying changes in water conditions, and providing actionable information without requiring constant manual sampling.

What we are demonstrating

Our current prototype demonstrates the core concept through:

6-servo sine-wave fin propulsion → water-quality sensing → onboard processing → camera-based monitoring → GPS tracking. version-1

The project combines biomimetic robotics, embedded systems, IoT, AI, and environmental monitoring to create a more intelligent and sustainable approach to aquatic exploration.

Code

Coding

#define PH_PIN A0
#define TURBIDITY_PIN A1
#define TDS_PIN A2

#define LEFT_PWM 5
#define LEFT_DIR 4
#define RIGHT_PWM 6
#define RIGHT_DIR 7

#define VREF 5.0

int motorSpeed = 150;

float phValues[] = {6.5, 7.0, 7.2, 7.5, 8.0};
float tempValues[] = {25.0, 26.0, 27.0, 28.0, 29.0, 30.0};

int phIndex = 0;
int tempIndex = 0;

unsigned long lastChange = 0;

void setup()
{
  Serial.begin(115200);

  pinMode(PH_PIN, INPUT);
  pinMode(TURBIDITY_PIN, INPUT);
  pinMode(TDS_PIN, INPUT);

  pinMode(LEFT_PWM, OUTPUT);
  pinMode(LEFT_DIR, OUTPUT);
  pinMode(RIGHT_PWM, OUTPUT);
  pinMode(RIGHT_DIR, OUTPUT);

  stopRobot();

  Serial.println("Water Quality Monitoring Robot");
  Serial.println("--------------------------------");
}

void loop()
{
  // Change simulated pH and temperature every 10 seconds
  if (millis() - lastChange >= 10000)
  {
    lastChange = millis();

    phIndex++;
    if (phIndex >= 5)
      phIndex = 0;

    tempIndex++;
    if (tempIndex >= 6)
      tempIndex = 0;
  }

  float pH = phValues[phIndex];
  float temperature = tempValues[tempIndex];

  // ---------------- TURBIDITY ----------------
  long turbiditySum = 0;

  for (int i = 0; i < 20; i++)
  {
    turbiditySum += analogRead(TURBIDITY_PIN);
    delay(2);
  }

  float turbidityADC = turbiditySum / 20.0;

  float turbidityVoltage =
      turbidityADC * VREF / 1023.0;


  // ---------------- TDS ----------------
  long tdsSum = 0;

  for (int i = 0; i < 30; i++)
  {
    tdsSum += analogRead(TDS_PIN);
    delay(2);
  }

  float tdsADC = tdsSum / 30.0;

  float tdsVoltage =
      tdsADC * VREF / 1023.0;


  // Temperature compensation
  float compensation =
      1.0 + 0.02 * (temperature - 25.0);

  float compensatedVoltage =
      tdsVoltage / compensation;


  // TDS calculation
  float tds =
      (133.42 * compensatedVoltage * compensatedVoltage * compensatedVoltage)
      - (255.86 * compensatedVoltage * compensatedVoltage)
      + (857.39 * compensatedVoltage);

  tds = tds * 0.5;

  if (tds < 0)
    tds = 0;


  // ---------------- WATER QUALITY ----------------

  bool safeWater = true;

  if (pH < 6.5 || pH > 8.5)
    safeWater = false;

  if (tds > 1000)
    safeWater = false;


  // ---------------- MOTOR CONTROL ----------------

  if (safeWater)
  {
    moveForward();
  }
  else
  {
    stopRobot();
  }


  // ---------------- SERIAL MONITOR ----------------

  Serial.print("Temperature: ");
  Serial.print(temperature, 1);
  Serial.print(" C");

  Serial.print(" | pH: ");
  Serial.print(pH, 2);

  Serial.print(" | Turbidity: ");
  Serial.print(turbidityVoltage, 3);
  Serial.print(" V");

  Serial.print(" | TDS: ");
  Serial.print(tds, 0);
  Serial.print(" ppm");

  Serial.print(" | Status: ");

  if (safeWater)
    Serial.println("SAFE - ROBOT MOVING");
  else
    Serial.println("UNSAFE - ROBOT STOPPED");

  delay(1000);
}


// ---------------- MOVE FORWARD ----------------

void moveForward()
{
  digitalWrite(LEFT_DIR, HIGH);
  digitalWrite(RIGHT_DIR, HIGH);

  analogWrite(LEFT_PWM, motorSpeed);
  analogWrite(RIGHT_PWM, motorSpeed);
}


// ---------------- STOP ROBOT ----------------

void stopRobot()
{
  analogWrite(LEFT_PWM, 0);
  analogWrite(RIGHT_PWM, 0);
}