Underwater Technologies

Anthony Squaire – Industrial and Systems Engineer – Team Lead

Alan Mattice – Mechanical Engineer – Lead Engineer

Brian Bullen – Mechanical Engineer

Charles Trumble – Mechanical Engineer

Cody Ture – Mechanical Engineer

Aron Khan – Electrical Engineer

Jeff Cowan – Electrical Engineer

Andre McRucker – Computer Engineer

P08454 – Thruster for a Remotely Operated Vehicle

Multidisciplinary Engineering Design

Program

Project Scope

Derived from one of the most successful projects in RIT’s history

Mission:To create a thruster for an underwater remotely operated vehicle (ROV) that is integrated with an ROV light design. This design shall be accessible to any person or persons who wish to use and/or modify it in the future.

P06606 – An Underwater ROV

Customers:Dresser-Rand has graciously donated the majority of the funds for this project. Hydroacoustics Inc. has supplied many resources to the project. Dr. Hensel and the Mechanical Engineering Department have supplied leadership and guidance through the design process.

Current DesignsTecnadyne Model 260:

$4,000.00

High Power Consumption (80W)

Very in-efficient in reverse

•Only 1/3 of forward thrust

Seabotix Model 150:

$1,000.00

Inefficient Thrust

No possible design variances

Competitor company for Hydroacoustics Inc.

Top Right: Seabotix Model 150

Left: Tecnadyne Model 260

Customer Requirements•Need more efficient thrust, ie. better thrust with lower power consumption

•Must be easily mountable to the Hydroacoustics Inc. ROV

•Needs to be operational up to 400ft (121.92m) of water, roughly 173psi (1192.8kPa) of pressure

•Needs to work in a large range of temperatures

•Modular, open source design so that any person or persons can use and/or modify the design

•Needs to comply with all federal, state, and local laws, including the policies and procedures of RIT

Design ProcessDecisions, Decisions, Decisions:

Shaft Seal – Decide between magnetic coupling or dynamic seal

Answer: The magnetic coupling was chosen because allows for a much simpler seal, gives protection to the motor and impeller, and is frictionless

Motor – Brushed or Brushless?

Answer: Brushless was chosen because of there being reduced losses and the use of Hall Sensors for feedback

Impeller – Design or use pre-existent designs?

Answer: Decision was to use pre-existent impeller designs. Computer muffin fans have perfect sized impellers for the projects application.

Design ProcessNozzle – Rice or Kort Nozzle?

Answer: The Rice nozzle was chosen based on it’s reduced drag through the fluid and a better geometry to promote increased thrust

Communication – Use single microcontroller for all thrusters or single for each?

Answer: Decision was to use a single microcontroller in each separate thruster or light. Allows the ROV to “limp” on

Nozzle Comparison

Kort Nozzle

Relatively Simple Geometry

High Circulation off Leading Edge

Rice Nozzle

Lower Drag Coefficient

Improved Flow Geometry

System ArchitectureNozzle

EntranceImpeller Nozzle Exit

Water Water Water

ImpellerShaft

MotorHall

Sensors

Motor Driver

Water

Microcontroller

TopsideControl (GUI)

BatteryPacks

PowerBoard

Legend

: Water

: Forward Communication

: Feedback

User

Final DesignSpecial Mechanical Features:

•Magnetic Coupling – No dynamic Seals

•Aluminum Housing – Lightweight and strong

•Rice Nozzle – Low drag and increased thrust

•Polymer Membrane – High strength PEEK (Polyetheretherkeytone) material

•Modular Housing – Used for both thruster and light

Final DesignSpecial Electrical/ Software Features:

•Feedback via Hall Sensors – Monitors position, speed and direction of the rotor, allows for synchronous control and fine tuning

•Motor driver – 5.6A peak with over-current protection, enable, forward/reverse, variable speed using pulse width modulation

•ATmega168 Microcontroller – Efficiently uses power, and has numerous PWM channels

•Topside GUI – Made using GTK to control thrusters and lights

Board Layouts

Left: Microcontroller

Right: Motor Driver

ST Microelectronics Driver

ATmega168 Microcontroller

Engineering Specifications•Must have a continual forward thrust of at least 4.8 lbf (2.18kg)

•Must have a reverse thrust at least ¾ the value of the forward thrust

•Power consumption must be limited to under 80W

•Impeller shaft must be balanced to within 0.001in (0.0254mm)

•Must withstand pressures up to 173psi (1192.8kPa)

•Should be of comparable weight and volume to both the Tecnadyne Model 260 and the Seabotix Model 150

•Needs to operate at ambient temperatures ranging from 38 to 75oF (3.3 to 23.9oC)

•Should be able to run for 168 hours without failures

Design VerificationSpecification

NumberDesign Specification Unit of Measure

Marginal Value

Ideal Value Pass/Fail

Physical Requirements1 Continual Thrust lbf 4.8 12 Fail2 Motor Power Draw Watts 80 50.4 Pass

3Mountable to the prototype ROV originally designed in SD team project P06606

Yes/No Yes Yes Pass

4 Uses standard (off the shelf) fittings / connections Yes/No Yes Yes Pass5 Seals must withstand at least 173 psi Yes/No Yes Yes Pass

6 Available Reverse ThrustRatio Reverse

to Forward1/2 3/4

Pass

7 Output shaft must be balanced

Amplitude of Vibration (Inches)

0.001 0.0001Pass

8 Depth (Pressure) Feet (psi) 400 (173) 800 (346) Pass9 Weight (in the air) Ounces (oz) 40 28 Fail10 Weight (in the water) Ounces (oz) 28 18 Fail11 Size Comparable to Market Competition Volume (in 3̂) 18.8851 15.8812 Fail12 Operate at Varied Temperatures Fahrenheit 38-75 34-100 Pass

Production and Document Constraints13 Open Architecture Design Yes/No Yes Yes Pass

14Open Source Documents and Drawings so that future SD teams can utilize this design in future projects

Yes/No Yes Yes Pass

Quality Control15 Robust Design Hours 168 252 Fail

Compatibility

16Modular so that the housing design integrates with the SD team project P08456

Yes/No Yes Yes Pass

Project CostsMechanical………………………………………………………….$1,623.74

Electrical………………………………………………………………$484.64

Machining (Production)……………...………………………………$2,150.00

Research and Development…………………………………………...$563.55

Total Project Cost: $2,671.93

Projected Cost per Thruster: $668.00

Man Hours……………………………………………….……..2116 Hours

For The Future…•Place thrusters on the Hydroacoustics Inc. ROV named Proteus to test design characteristics

•Maximize the thrust to weight ratio by reducing the wall thickness of the light housing

•Maximize the thrust to power consumption ratio by reducing friction losses in places such as the gearbox

•Use a new motor supplier

•A future RIT MSD project could be an open source ROV design and these thrusters can be integrated into the design

•Look at modularity in the software and electronics

•Possible uses for land-based and hybrid (land and sea) vehicles

Questions?