🌊 Project Neptune — Autonomous Water Sampling Boat

Autonomous water quality monitoring system with a 6-position sample carousel, real-time telemetry over 433 MHz radio, and live camera feed.

Overview

Project Neptune is a school engineering project developed at Zespół Szkół nr 10 im. prof. Janusza Groszkowskiego w Zabrzu in cooperation with Politechnika Śląska (RAU3). The system allows remote collection and real-time analysis of water quality samples from lakes, rivers, and reservoirs.

A remotely controlled boat carries a rotating carousel of 6 test tubes. Sensors (pH, TDS, temperature, conductivity) are immersed in each sample in turn, and the results stream wirelessly to a Windows PC application. The operator controls the boat using WASD keys while watching a live 64 MP camera feed.

Key features:

6-position sample carousel with quadrature encoder feedback (HEDL-5540-A12)
Water quality sensors: pH, TDS, temperature (DS18B20), conductivity (EC)
433 MHz NRF905 radio link (up to ~150 m open water)
Live 1280×720 MJPEG video stream over Wi-Fi
WPF desktop application with dockable panels, live charts (LiveCharts), and data history
SQLite local logging on the boat
Battery voltage monitoring (INA219)
WASD boat control with 500 ms safety watchdog

System Architecture

┌─────────────────────────────┐         ┌─────────────────────────┐
│   Windows PC (WPF App)      │         │   RPi #1 — Base Station │
│                             │◄──TCP───│                         │
│  • Live charts (LiveCharts) │  JSON   │   base_station.py       │
│  • Data table (150 records) │  WiFi   │   TCP server :5000      │
│  • Camera stream viewer     │         │   NRF905 transceiver    │
│  • WSAD boat control        │         │   (SPI + GPIO)          │
│  • Command buttons          │         └───────────┬─────────────┘
│                             │                     │  NRF905
│  CameraWindow ──────────────┼──── HTTP ───────────┤  433 MHz
│  (MJPEG :8080)              │     WiFi            │  half-duplex
└─────────────────────────────┘                     │
                                         ┌───────────▼─────────────┐
                                         │   Arduino Nano          │
                                         │   nrf905_transmitter    │
                                         │   Cytron MDD20A driver  │
                                         │   Watchdog 500 ms       │
                                         └───────────┬─────────────┘
                                                     │  Serial 115200
                                         ┌───────────▼─────────────┐
                                         │   RPi #2 — Boat Station │
                                         │   master.py             │
                                         │   Sensors / Carousel    │
                                         │   MJPEG server :8080    │
                                         │   SQLite (pomiary.db)   │
                                         └─────────────────────────┘

Hardware Components

Component	Role
Raspberry Pi 4 (#1)	Base station — NRF905 transceiver, TCP server
Raspberry Pi 4 (#2)	Boat — sensors, carousel control, camera server
Arduino Nano	RF-to-Serial relay, motor driver interface
NRF905 (×2)	433 MHz radio, 32-byte packets, ~150 m range
ArduCam 64MP (CSI)	MJPEG camera on RPi #2
TP-Link T3U Plus	USB Wi-Fi adapter on RPi #2 (RTL8822BU)
ADS1115	16-bit ADC — pH, TDS, EC sensors
INA219	Battery voltage monitor (I2C, shared bus with ADS)
DS18B20	1-Wire temperature sensor
28BYJ-48 + ULN2003	Stepper motor for carousel rotation
HEDL-5540-A12	500 CPR quadrature encoder for carousel
MG995 Servo	Needle positioning (sample/retract)
IRF520 MOSFET (×2)	Pump control (GPIO 24 & 25, 12 V)
Cytron MDD20A	Dual motor driver for boat propulsion

Repository Structure

Project_Neptune/
│
├── POLSL - Raspberry/          # RPi #2 — Boat software
│   ├── master.py               # Main program (sensors, carousel, camera, serial)
│   ├── sensors.py              # Sensor reading module
│   ├── carousele_calibration.py# Interactive calibration tool
│   ├── camera_stream.py        # MJPEG server prototype
│   ├── read_ph.py              # pH diagnostic
│   ├── read_tds_robot.py       # TDS diagnostic
│   ├── read_temp.py            # Temperature diagnostic
│   ├── read_cond.py            # Conductivity diagnostic
│   ├── read_all.py             # All sensors at once
│   ├── test_telemetrii.py      # Telemetry test
│   ├── VCC_measure_test.py     # Voltage test
│   ├── GNSS_calibration.py     # GPS calibration utility
│   └── pomiary.db              # SQLite database (auto-created)
│
├── ja8 - Raspberry/            # RPi #1 — Base station software
│   └── base_station.py         # NRF905 RX/TX + TCP server
│
├── nrf905_transmitter/         # Arduino firmware
│   ├── nrf905_transmitter.ino  # Main sketch
│   └── diagnoza/
│       └── diagnoza.ino        # Diagnostic sketch
│
├── PN_groundStation/           # Windows WPF application (C#)
│   ├── PN_Ground_Station/      # Main project
│   │   ├── MainWindow.xaml/.cs
│   │   ├── TcpDataClient.cs
│   │   ├── SensorData.cs
│   │   ├── EngineController.cs (BoatController)
│   │   └── Dock Windows/
│   │       ├── CameraWindow.xaml/.cs
│   │       ├── ChartsWindow.xaml/.cs
│   │       ├── ControlsWindow.xaml/.cs
│   │       └── DataGridWindow.xaml/.cs
│   ├── PN_Ground_StationTests/ # Unit tests (MSTest)
│   │   └── SensorDataTests.cs
│   └── NetDock/                # Custom docking library
│       ├── DockSurface.cs
│       ├── DockItem.cs
│       └── DockWindow.cs
│
└── pinout.txt                  # GPIO reference

Software Modules

RPi #2 — `master.py`

The main program for the boat. Runs 5 daemon threads simultaneously:

Thread	Frequency	Function
`serial_listener()`	continuous	Receives commands from Arduino via Serial
`measurement_loop()`	every 2 s	Reads all sensors during active measurement
`_encoder_poll_loop()`	10 kHz	Polls HEDL-5540 GPIO for carousel positioning
`camera_capture_loop()`	~30 fps	Extracts JPEG frames from rpicam-vid
`camera_server_loop()`	on demand	HTTP/MJPEG server on port 8080

GPIO pinout (RPi #2):

GPIO (BCM)	Physical	Device
GPIO 4	Pin 7	DS18B20 (1-Wire)
GPIO 17/27/22/23	11/13/15/16	28BYJ-48 stepper (IN1–IN4)
GPIO 24	Pin 18	MOSFET pump 1
GPIO 25	Pin 22	MOSFET pump 2
GPIO 18	Pin 12	Servo MG995 (PWM 50 Hz)
GPIO 16/20/21	36/38/40	HEDL-5540 (A / B / Index)
I2C SDA/SCL	Pin 3/5	ADS1115 + INA219
USB `/dev/ttyUSB0`	USB	Arduino Nano (Serial 115200)

RPi #1 — `base_station.py`

TCP server on port 5000. Receives sensor data packets from Arduino via NRF905 and forwards them as JSON to the WPF application. Also receives JSON commands from WPF and transmits them as 32-byte NRF905 packets to Arduino.

NRF905 GPIO (RPi #1):

CE → GPIO 17, TX_EN → GPIO 27, DR → GPIO 22, PWR → GPIO 23, SPI0

Arduino — `nrf905_transmitter.ino`

Full-duplex relay between NRF905 and RPi #2 via Serial. Also directly drives the Cytron MDD20A motor controller.

CMD_BOAT_DRIVE: immediately sets motor speed without waiting for RPi #2
Watchdog: no CMD_BOAT_DRIVE for 500 ms → automatic stop

Arduino pinout:

NRF905: CSN=D10, CE=D9, PWR=D8, TX_EN=D7, DR=D5
Motors: LEFT_PWM=D3, LEFT_DIR=D2, RIGHT_PWM=D6, RIGHT_DIR=D4
Serial: TX→RPi GPIO15, RX→RPi GPIO14

Communication Protocol

NRF905 packet — Command (32 bytes, PC → boat)

struct CommandPacket {
  uint8_t  command;    // 0x01–0x07, 0x20
  uint16_t param1;     // e.g. measurement duration [s]
  uint16_t param2;     // e.g. right motor speed
  uint32_t timestamp;
  uint8_t  reserved[22];
  uint8_t  crc;
};

Code	Command	Description
`0x01`	`CMD_MEASURE_START`	Start measurement for `param1` seconds
`0x02`	`CMD_MEASURE_STOP`	Stop active measurement
`0x03`	`CMD_PUMP_ON`	Turn on pump 1 (fill tank)
`0x04`	`CMD_PUMP_OFF`	Turn off pump 1
`0x05`	`CMD_STATUS_REQUEST`	Request status packet
`0x06`	`CMD_SAMPLES_LOADING`	Load sample sequence (pump 2 + servo + carousel)
`0x07`	`CMD_REJECT_SAMPLE`	Reject sample (pump 2 + reject position)
`0x20`	`CMD_BOAT_DRIVE`	Drive: `param1`=left motor, `param2`=right (0–200, 100=stop)

TCP JSON — sensor data packet

{
  "station_id": 1,
  "ph": 7.24,
  "tds": 183.5,
  "temperature": 18.3,
  "conductivity": 367.1,
  "timestamp": 3600,
  "battery_voltage": 12.41,
  "error_flags": 0,
  "received_at": "2025-09-15T14:23:01"
}

TCP JSON — command (PC → RPi #1)

{"command": "boat_drive", "param1": 190, "param2": 190, "timestamp": "..."}

WPF Ground Station

Built with .NET 8.0 / WPF. Uses LiveCharts for real-time plots and a custom NetDock library for dockable panels.

Dockable panels

Panel	Default position	Contents
📷 Camera	Left	Live MJPEG stream from boat camera
📊 Charts	Top-right	Real-time line charts: pH, TDS, temperature, EC
⚙️ Controls	Bottom-left	Sensor readouts, command buttons, WSAD control
📜 Data History	Right	Scrollable table of last 150 measurements

WSAD boat control

Keys	Left motor	Right motor	Motion
W	+90 → 190	+90 → 190	Forward
S	−90 → 10	−90 → 10	Reverse
A	−90 → 10	+90 → 190	Rotate left
D	+90 → 190	−90 → 10	Rotate right
W+A	120	180	Arc left forward
W+D	180	120	Arc right forward
S+A	80	20	Arc left reverse
S+D	20	80	Arc right reverse
Space	100	100	Emergency stop

Click Activate WSAD Control in the Controls panel, then click inside the panel to focus it before steering.

Camera stream

Enter the boat's IP address in the Camera panel and click Connect. The URL used is http://<IP>:8080/stream.

Getting Started

Prerequisites

RPi #2 (boat): Raspberry Pi OS (64-bit), Python 3.13+
RPi #1 (base): Raspberry Pi OS (64-bit), Python 3.13+
Arduino: Arduino IDE 2.x
PC: Windows 10/11, .NET 8.0 SDK, Visual Studio 2022

RPi #2 setup

# Install Python dependencies
pip install RPi.GPIO adafruit-circuitpython-ads1x15 \
            adafruit-circuitpython-ina219 adafruit-extended-bus \
            --break-system-packages

# Run calibration first
python3 carousele_calibration.py

# Then run the main program
python3 master.py

Enable I2C and 1-Wire in raspi-config → Interface Options.

RPi #1 setup

pip install RPi.GPIO spidev --break-system-packages
python3 base_station.py

Enable SPI in raspi-config → Interface Options.

Arduino

Open nrf905_transmitter/nrf905_transmitter.ino in Arduino IDE and upload to Arduino Nano (board: Arduino Nano, processor: ATmega328P (Old Bootloader)).

WPF Application

cd PN_groundStation/PN_Ground_Station
dotnet build
dotnet run --project PN_Ground_Station

Or open PN_Ground_Station.sln in Visual Studio 2022 and press F5.

In the app: enter RPi #1's IP address and port 5000, click Connect.

Calibration

Run carousele_calibration.py on RPi #2 before first use:

Option	Mode	What it sets
1	Servo calibration	`SERVO_UP` and `SERVO_DOWN` duty cycle values
2	Stepper (steps)	`STEPS_PER_POSITION` — fallback mode without encoder
3	Stepper (ticks)	`TICKS_PER_POSITION` — main encoder-based positioning
4	Full sequence	End-to-end test of the complete sample loading cycle

After calibration, update the constants at the top of master.py:

TICKS_PER_POSITION = 165  # from option 3
SERVO_UP  = 11.7          # from option 1
SERVO_DOWN = 2.5          # from option 1

Water Quality Algorithm

SensorData.GetWaterQuality() uses a weighted scoring system:

Parameter	Weight	Scoring
pH	40 pts	pH < 4.0 or > 10.0 → CRITICAL; 6.5–8.5 → 40 pts; 6.0–9.0 → 20 pts
TDS	35 pts	TDS > 1000 → UNACCEPTABLE; ≤ 150 → 35 pts; ≤ 300 → 30 pts; ≤ 600 → 15 pts
EC	25 pts	EC > 2000 → −20 pts; ≤ 600 → 25 pts; ≤ 1200 → 15 pts

Final rating:

Score	Result
< 0 (critical flag)	CRITICAL
< 30	UNACCEPTABLE
< 50	POOR
< 70	ACCEPTABLE
< 90	GOOD
≥ 90	EXCELLENT

Unit Tests

The PN_Ground_StationTests project contains 16 MSTest unit tests for GetWaterQuality():

cd PN_groundStation/PN_Ground_Station
dotnet test

Test coverage includes: CRITICAL (pH out of range), UNACCEPTABLE (high TDS), POOR, ACCEPTABLE, GOOD, EXCELLENT, boundary values (pH=4.0, TDS=50), priority (CRITICAL pH overrides excellent TDS), and all-zeros edge case.

Authors

Ślusarz Bartłomiej(code), Moj Cyprian(models 3D), Sot Krzysztof(electronics)
Klasa IV, Technik Programista
Zespół Szkół nr 10 im. prof. Janusza Groszkowskiego w Zabrzu
we współpracy z Politechniką Śląską — Katedra Automatyki i Robotyki (RAU3)

Name		Name	Last commit message	Last commit date
Latest commit History 32 Commits
.vscode		.vscode
PN_groundStation		PN_groundStation
POLSL - Raspberry		POLSL - Raspberry
ja8 - Raspberry		ja8 - Raspberry
nrf905_transmitter		nrf905_transmitter
LICENSE		LICENSE
README.md		README.md
pinout.txt		pinout.txt

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🌊 Project Neptune — Autonomous Water Sampling Boat

Table of Contents

Overview

System Architecture

Hardware Components

Repository Structure

Software Modules

RPi #2 — `master.py`

RPi #1 — `base_station.py`

Arduino — `nrf905_transmitter.ino`

Communication Protocol

NRF905 packet — Command (32 bytes, PC → boat)

TCP JSON — sensor data packet

TCP JSON — command (PC → RPi #1)

WPF Ground Station

Dockable panels

WSAD boat control

Camera stream

Getting Started

Prerequisites

RPi #2 setup

RPi #1 setup

Arduino

WPF Application

Calibration

Water Quality Algorithm

Unit Tests

Authors

About

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🌊 Project Neptune — Autonomous Water Sampling Boat

Table of Contents

Overview

System Architecture

Hardware Components

Repository Structure

Software Modules

RPi #2 — master.py

RPi #1 — base_station.py

Arduino — nrf905_transmitter.ino

Communication Protocol

NRF905 packet — Command (32 bytes, PC → boat)

TCP JSON — sensor data packet

TCP JSON — command (PC → RPi #1)

WPF Ground Station

Dockable panels

WSAD boat control

Camera stream

Getting Started

Prerequisites

RPi #2 setup

RPi #1 setup

Arduino

WPF Application

Calibration

Water Quality Algorithm

Unit Tests

Authors

About

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RPi #2 — `master.py`

RPi #1 — `base_station.py`

Arduino — `nrf905_transmitter.ino`

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