1 of 42

Team 8: Nautiloid�Critical Design Review

Team:

Daniel Mitchum - Motherboard/Firmware

Justin Hodakowski - System Architect/Mechanical

Riley Pratt - Recovery Signal System

Camron’ Johnson - Sensors/Sensor Comms.

Chris Mori - Front End/Wireless Comms.

​

Mentor:

Dr. John Muth

2 of 42

Nautiloid: Submersible Sensor Platform

Team: Camron’ Johnson, Chris Mori, Daniel Mitchum, Justin Hodakowski, Riley Pratt

Mentor: Dr. John Muth

Problem Statement

There is a need for an affordable, reusable solution for collecting ocean data at depths of up to 100 meters.

​

Key Requirements

  • Maximum 3" outer diameter
  • Reach & return from 100m depth
  • Recoverable and reusable
  • Designed and documented for future development

Target Customers

  • Oceanographic researchers

​

  • Future Nautiloid development teams

​

  • Hobbyists

User Device + Application

3 of 42

Product Requirement Changes�since PDR and Tech. Demo.

  • Must demonstrate an active battery life of one hour
    • Must actively operate for a 5-20 minute mission
    • Must be able to emit recovery signal for
  • Must include on-board GPS
  • Must include wireless charging capability
  • Must include dedicated flight controller

4 of 42

Technical Design Changes�since PDR and Tech. Demo.

  • BLE to Bluetooth Classic
  • Change Arduino framework to ESP-IDF framework
  • Addition of flight controller with Ardusub for position tracking and depth control
  • GitHub repositories setup and organized

​

5 of 42

Functional Block Diagram

6 of 42

System Functional Flowchart

7 of 42

User Flowchart

8 of 42

GitHub

Go!

9 of 42

Hardware Architecture

Antenna (Wired to LoRa Module)

Sensors (Environment Wired to Sensor Platforms)

Sensor Platform x2 I2C/PWR

RFM95 LoRa Breakout I2C/PWR SPI 2

SD Card Module I2C/PWR SPI 1

Motherboard(Buetooth) I2C/PWR SPI Host UART 5 Wires

Adafruit GPS Breakout I2C/PWR UART 5 Wires

AKK Flight Controller I2C/PWR 5 Wires

Sensor Platform I2C/PWR 5 Wires

Controls Circuitry I2C/PWR 5 Wires

Power Board(Batt) I2C/PWR 2 Wires

LiPo Battery 2 wires

Depth Sensor (I2C Wires)

​

​

Buoyancy Budget Spreadsheet

Battery

PCB Stackup and Interconnects

Key: Part of Stackup

10 of 42

End Cap Sensor Penetration

  • Ordered several acrylic end caps
  • Intend to test different methods of penetration
    • Wetlink penetrators
    • Bare Cable with epoxy
    • Test penetrating the side acrylic hull
    • Backup: potted penetrator

11 of 42

Mechanical BOM

Hull

Qty

Unit Cost

Cost

Vendor

Link

PO Sheet

O-ring flanges (2" Locking Series)

2

$27.00

$54.00

Blue Robotics

5

End Cap - Acrylic - Blank - 600m

2

$12.00

$24.00

Blue Robotics

5

Cast Acrylic Plastic - 300 mm (11.8") - 150 m

1

$32.00

$32.00

Blue Robotics

5

WLP-M06-4.5MM-HC

5

$10.00

$50.00

Blue Robotics

5

WLP-M06-7.5MM-HC

5

$10.00

$50.00

Blue Robotics

5

Fathom Slim ROV Tether (by the meter) - 2m

1

$6.00

$6.00

Blue Robotics

5

Fathom ROV Tether (by the meter) - 2m

1

$10.00

$10.00

Blue Robotics

5

Thixo LV 2:1 Epoxy Adhesive

1

$28.99

$28.99

TotalBoat

5

​

​

Total:

$254.99

​

​

​

12 of 42

Current Hardware Setup sans Software Integration

13 of 42

Sensor Platform: Block Diagram

14 of 42

Conductivity Sensor: Schematic

15 of 42

Sensor Platform / Sensors: Power Budget

Device

Min. Power

Avg. Power

Max. Power

ESP32 Dev. Kit

-

-

260mA

Bar30 Depth/Pressure Sensor

​

​

-

-

1.25mA

16 of 42

Sensor Platform / Sensors: BOM

Reference

Qty.

Description

Value

Package/Case

Mfg.

Mfg. P/N

Datasheet

Price Per

Total Price

U1

1

ESP32 Development Board WiFi+Bluetooth

-

Non-standard

Makerfabs

OIE32ESPD

$8.90

$8.90

U2

1

Bar30 High-Resolution 300m Depth/Pressure Sensor

​

​

-

Non-standard

​

​

BlueRobotics

BAR30-SENSOR-R1-RP

$72

$72

​

​

​

​

​

​

​

​

Total:

$80.90

17 of 42

Motherboard: �Block Diagram

18 of 42

Motherboard: �Schematic

19 of 42

Motherboard: �Power Budget

Device

Min. Power

Avg. Power

Max. Power

ESP32 Dev. Kit

-

-

260mA

SD Card Module

-

-

50mA

Measure current draw and calculate power consumption via powering prototype PCB.�Update these figures post-testing.�See https://lastminuteengineers.com/esp32-sleep-modes-power-consumption/ for ESP32 power testing.

20 of 42

Motherboard: �Bill of Materials

Reference

Qty.

Description

Value

Package/Case

Mfg.

Mfg. P/N

Datasheet

Price Per

Total Price

U1

1

ESP32 Development Board WiFi+Bluetooth

-

Non-standard

Makerfabs

OIE32ESPD

$8.90

$8.90

U2

1

SD Card Socket Module

-

Non-standard

Makerfabs

MCIA000SD

$0.45

$0.45

-

1

SD Card 16GB

16GB

-

PNY

P-SDHC16G4X2-GE

$8.93

$8.93

​

​

​

​

​

​

​

​

Total:

$18.28

21 of 42

Motherboard: �Software Architecture

22 of 42

Motherboard: �Software Architecture cont.

23 of 42

Motherboard: �Software Architecture cont.

24 of 42

Motherboard: �Subsystem Communication

Subsystem

Method of Communication

User Device

Bluetooth Classic: SPP�see Front End software for detail

Sensor Platform

I2C

Power Board

will be I2C

Flight Controller

will be USB/UART

LoRa Module

will be SPI

SD Card Module

SPI

25 of 42

Recovery System: Block Diagram

SPI

SPI

26 of 42

Recovery System: Schematic

27 of 42

Recovery System: Power Budget

Device

Min. Power

Avg. Power

Max. Power

ESP32 Dev. Kit

-

-

260mA

RFM95

-

-

30mA

28 of 42

Recovery System: Bill of Materials

Reference

Qty.

Description

Value

Package/Case

Mfg.

Mfg. P/N

Datasheet

Price Per

Total Price

U1

2

ESP32 Development Board WiFi+Bluetooth

-

Non-standard

Makerfabs

OIE32ESPD

$8.90

$8.90

U2

2

Adafruit RFM 95

​

-

Non-standard

Adafruit

3072

​

$19.95

39.90

​

​

​

​

​

​

​

​

​

Total:

$57.70

29 of 42

Wireless Communications Architecture

  • Bluetooth Classic
  • User portal
    • PyBluez core
  • Serial Port Profile
  • Sockets

30 of 42

Intersystem Communications

  • RFCOMMS Bluetooth protocol
  • Byte array sending
  • Functions under front-end interface

​

31 of 42

Bill of Materials

  • Windows machine
  • Functioning Windows Bluetooth drivers
  • ESP32 w/ Bluetooth Classic
  • ESP32 Bluetooth API’s

32 of 42

Bluetooth Power Budget

​

Min (mA)

Max (mA)

Average (mA)

Scan

30.8

106.4

37.8

Transmission

90.1

123

100.4

Source

33 of 42

Front End Software Architecture

34 of 42

Front End Architecture

​

35 of 42

Front End Interface

36 of 42

Intermodule Communication

  • Front-end working atop
    • FreeRTOS
    • Unix like commands using FreeRTOS library functions
  • Bluetooth Classic SPP RFCOMM

​

37 of 42

Front End Bill Of Materials

  • Python 3.9.4
    • PyBlues
    • sys
    • ctypes
  • Windows PC
    • Bluetooth capable

38 of 42

Front End Sofware Packaging

  • Windows shell script to
    • Install/verify installation of Python 3.9.4
    • Install all required packages
    • Verify bluetooth drivers up to date

39 of 42

Project Requirements and Test Plans

Go!

40 of 42

Project Timeline: Major Milestones

  • Sub-systems working independently: 02/25/2022�
  • Sub-systems integrated and working: 03/15/2022�
  • PCB Designs for sub-systems: 03/22/2022�
  • Documentation Packages for sub-systems:
    • Preliminary: 02/27/2022
    • Final: 03/25/2022

​

Full project timeline is located in Team Charter.

41 of 42

Project Charter: Projected BOM

Go!

42 of 42

Tech Demos