Multidisciplinary Engineering Senior Design

Project 06606 Underwater ROV Preliminary Design Review

11/11/05

Project Sponsor: Daniel Scoville

Team Members: Josh Figler, Chris Nassar, Matt Paluch, Antoine Joly, Jason Caulk, Scott Gerenser, Larry Shaver, Daniel

Scoville

Team Mentor: Prof. Walter

Kate Gleason College of EngineeringRochester Institute of Technology

ROV Project Overview

Goal• Construct an underwater vehicle capable of

diving 400 ft deep to video an underwater shipwreck from the mid 1800’s in Lake Ontario

Side Scan Sonar Images of the Wreck

Major Project Needs

• Vehicle movement joystick controlled• Vehicle speed must be variable • Minimum tether diameter to reduce drag• Temp and depth data returned to operator• 400ft operating depth• 4.5°C operating environment• Vehicle must be deployable by at most two

people

The Design Process

• Develop needs assessment• Create preliminary concepts• Assess concept feasibility• Determine project schedule (Gantt chart)

Objective Tree

Key Requirements & Critical Parameters

• Total cost less than $3000• Finish within 20 weeks• Doesn’t leak• Can send video to boat• Controlled from boat• Recoverable in emergency situation• Reliable communications• Able to illuminate at least 20 ft in clear water• Measures and relays current depth

Overall System Diagram/Block Diagram

ROV User Interface

• The ROV user interface is going to be implemented using Qt 4 which is a complete C++ Application framework for building GUI’s.

• The design of the GUI is such that there is one main window with several “Groups” of information that can be easily removed, added, changed, moved and resized within the code.

• The GUI displays information to the user that is required in order to control the ROV underwater. Some of the information displayed is:

– Depth– Temperature– Pressure

• The layout of the interface has already been determined and created and now needs to interact with the MCU which is on board the ROV. Most of this will be completed during the early parts of SD 2.

ROV User Interface

• There are several highly desirable features that would be useful and convenient to have on the GUI. Some of these features are:

– To have live video from the ROV fed directly to the GUI.– Speed Reporting.– Light selection to maximize power efficiency.– Some form of error reporting for the different components of the ROV.

• Due to constraints such as time, some of the desirable features will most likely have to be omitted. However, this is something that could easily be followed up on in the future.

• The GUI will have an “Admin” mode for the purposes of debugging and to follow the general theme for designing for testability.

• Designing for testability is one of the most important concepts that have and will continue to lead the design of the GUI for the ROV.

• Finally, a key feature of the GUI is that it will be portable between operating systems should the owner ever switch or update the machine he uses to run the ROV.

The RIT ROV Display

Communications

• One fiber optic line (approximately 3mm diameter) will be multiplexed to include one video line and up to five data lines.

• Prizm Inc’s Micromux will multiplex the video and data lines into the fiber optic line and de-multiplex the signals on the other end.

Microcontroller Requirements

• 16 GPIO• Low error baud rate generation• UART capable of RS232 interrupt driven communication• Real time clock with at least 10ms resolution for polling• PWM generation in the 1-10kHz band with a minimum of

8-bit resolution• Analog to digital conversion with a minimum of 8-bit

resolution from 0-5V

VCC

Motor 3 Fwd PWM

Analog Temp In

Analog Compass Sin In

0

*Camera Servo PWM

VCC

Motor 2 Rev PWM

C2

20pf

Analog Pressure In

Y115.36MHz

Motor 4 Rev PWM

Motor 2 Fwd PWM

MCU TX

Cam Select 2

C1

20pf

IC1

ATmega128

1011121314151617

3536373839404142

2526272829303132

23456789

5455565758596061

4445464748495051

3334431819

64

62

20

1

24

23

21 5222 53 63

PB0 (SS)PB1 (SCK)PB2 (MOSI)PB3 (MISO)PB4 (OC0)PB5 (OC1A)PB6 (OC1B)PB7 (OC2/OC1C)

PC0 (A8)PC1 (A9)PC2 (A10)PC3 (A11)PC4 (A12)PC5 (A13)PC6 (A14)PC7 (A15)

(SCL/INT0) PD0(SDA/INT1) PD1

(RxD1/INT2) PD2(TxD1/INT3) PD3

(IC1) PD4(XCK1) PD5

(T1) PD6(T2) PD7

(RxD0/PDI) PE0(TxD0/PDO) PE1(XCL0/AIN0) PE2

(OC3A/AIN1) PE3(OC3B/INT4) PE4(OC3C/INT5) PE5

(T3/INT6) PE6(IC3/INT7) PE7

(TDI/ADC7) PF7(TDO/ADC6) PF6(TMS/ADC5) PF5(TCK/ADC4) PF4

(ADC3) PF3(ADC2) PF2(ADC1) PF1(ADC0) PF0

PA7 (AD7)PA6 (AD6)PA5 (AD5)PA4 (AD4)PA3 (AD3)PA2 (AD2)PA1 (AD1)PA0 (AD0)

(WR) PG0(RD) PG1

(ALE) PG2(TOSC2) PG3(TOSC1) PG4

AVCC

AREF

RESET

PEN

XTAL1

XTAL2

VCC

VCC

GND

GND

GND

0

Motor 4 Fwd PWM

Motor 1 Rev PWM

Analog Compass Cos In

Cam Select 1

Motor 3 Rev PWM

Motor 1 Fwd PWM

MCU RX

Atmel AVR ATMega128L

• 2 – 16 bit compare timers with 3 compare modules each. These timers can be used for PWM generation. 7.5kHz can be generated using the clock frequency/8 with 8 bit resolution.

• Built in A/D converter with 10-bit resolution. Only 8-bit resolution is required by the pressure and temperature inputs.

• Built in differential A/D input. This option may be useful for finding the times when the navigational sinusoids cross.

• 15.36 MHz Crystal allows even baud rate generation (0% error for 9600 baud).

• Real-time clock with 1ms resolution attainable (60 overflows of the 8 bit timer)

• Real-time clock with 10ms resolution attainable (capture at clock counter = 150, clock prescaler of 1024). Much more real-time efficient with only 1 capture event required.

Pressure sensor

MSP 800 Series – MSI SENSORS

Hydrostatic pressure Depth

1 bar 10 meters

2 bars 20 meters

3 bars 30 meters

4 bars 40 meters

and so on …

 

When the ROV is 122 meters (400 feet) undersea level, the hydrostatic pressure will be equal to:

output voltage ofthe pressure sensor

hydrostatic pressure

Phydro_max = 12.2 bars = 176.9 PSI

0.5V 4.5V

MSP 800 Series – MSI SENSORS

RTD : Resistance Temperature Detector

Temperature probe

resistance ofthe probe

temperature

Temperature sensorWheatstone bridge

)()(2

5RRTD

RTDRVVV BAAB

What we would like is to have VAB = 0 when T=0°C.

For that we need to choose R = RTD(T=0°C).

Compass

Dinsmore R16552 axis analog compass

H-Bridge Concept• When high side (left) and low side (right)

are closed motor operates forward.

• When high side (right) and low

side (left) are closed motor operates

in reverse.

• Closing both switches on one

side is forbidden (causes short).

Our H-bridge Schematic

HI

V124Vdc

R7

10k

Q22N3904

R8

10k

R110k

R310k

R5

10k

Q5STP12PF06

Q4STF20NF06

R410k

Q3STF20NF06

Q12N3904

R210k

MOTOR

R6

10k

0

Q6STP12PF06

0

0

0

LO

Speed Control using PWM

• Pulse width modulation (PWM) is a powerful technique for controlling analog circuits with a microprocessor's digital outputs.

• By controlling analog circuits digitally, system costs and power consumption can be drastically reduced.

Prototype H-Bridge

Power?

Evaluate each additional concept against the

baseline, score each attribute as: 1 = much

worse than baseline concept 2 = worse than

baseline 3 = same as baseline 4 = better than

baseline 5= much better than baseline

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Suffi cient Team Member Skills? 4.0 4.0 2.0 1.0 4.0

Suffi cient Available Equipment? 5.0 5.0 4.5 1.0 5.0

Cost of Materials? 3.0 4.0 3.0 1.0 4.5

Cost of Purchased Components? 3.0 4.0 4.0 1.0 4.0

Complete by end of Winter Quarter? 3.0 3.0 2.0 1.0 2.0

Make Repeated Sequential Dives? 3.0 3.0 4.0 5.0 1.0

Manufacturing Technologies Needed? 3.0 3.0 3.0 1.0 3.0

Cool Technology for Excitement? 4.0 4.0 4.0 5.0 2.0

Adheres to Laws and Regulations? 5.0 5.0 4.0 1.0 1.0

Will Produce a Quality Product to Satisfy Sponsor? 5.0 5.0 4.0 2.0 1.0

Mean Score 3.8 4.0 3.5 1.9 2.8

Normalized Score 95.0% 100.0% 86.3% 47.5% 68.8%

And the winner is…….

• Batteries proved to be the more feasible choice.• Donation of tether without power cable makes

decision easy.

Battery Type

• Chose NiMH D-cells based on price and power to size ratio.

• Li too expensive for our budget.• Pb Acid too heavy.• NiCd not enough power.

Power Consumption

• Batteries packs will provide 24V and 10 amp hours. Approx. 240W/hr.

• Motors draw average 4 amps running at 24V. Each motor will draw 96 Watts.

• Only two motors on at the same time, therefore 192W total needed.

• Will run for over an hour on one battery pack. We have two.

• All other electronics will run off a separate 12V supply.

Lights and Video

•10 Watt HID Lamps

•6000K color Temp

•450 Face Lumens

•16 Deg. Beam Divergence

•Resolution 460 lines

•12 Volt supply

•110 milliamp power consumption

Multiplexer Board Schematic

ROV Frame

Light Housing

Fixed Camera Assembly

Tilting Camera Design Concept(To be finalized when RC servo is received)

Battery Enclosure

Electronics Housing

Overall Design: Putting the pieces together

ROV Sub System Donations Team Cost

Top Side Control $ 7,000.00 $ 92.73

Video Multiplexer Board $ 4.75 $ 1.03

Motor Driver Board $ 1,310.00 $ 1,378.68

Video and Lights $ 831.96 $ 252.47

Underwater light housing $ - $ 90.79

Underwater Video Camera housing $ - $ 55.44

Electronics housing $ - $ 69.94

Frame   $ 100.00

Battery Housing   $ 110.62

Sensors $ 125.00 $ 67.28

Bottom side Controls $ 94.05 $ 1.52

Power Source $ - $ 507.50

$ 9,365.76 $2,728.00

Anticipated Design Challenges/Risk

• Time• Budget• Integrating systems

SD II Project Plan

• Develop test plan• Complete construction with ample time for

testing• Use holiday breaks to get a head start on

physical construction

Questions

?

System Schematic