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ROV Snoopy and ROV Woodstock Cambridge Underwater Robotics Team Cambridge Rindge and Latin School Cambridge, MA 02138 E. Huo (2004), C. Grouard (2004), C. Katrak (2004), C. Stefanov-Wagner (2006) Mr. Paul McGuinness June 11, 2004
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ROV Snoopy and ROV Woodstock

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Page 1: ROV Snoopy and ROV Woodstock

ROV Snoopy and ROV Woodstock

Cambridge Underwater Robotics Team

Cambridge Rindge and Latin School

Cambridge, MA 02138

E. Huo (2004), C. Grouard (2004), C. Katrak (2004),

C. Stefanov-Wagner (2006)

Mr. Paul McGuinness

June 11, 2004

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Abstract

The team is now competing in the MATE ROV Competition for its

third year. The three members from last year recruited a new member,

and began to meet after school once weekly in November. Until February,

meetings consisted primarily of brainstorming, considering various

strategies and designs, which could best complete the mission tasks. The

decision was made to attempt all mission tasks, and a rough design was

chosen of two small robots, controlled separately, with high

maneuverability and mostly passive devices. Designs were then refined,

with construction beginning in early March. In the final two weeks before

Regionals, the vehicles were tested in the school pool and modified as

necessary.

Fol lowing regionals, we disassembled the robots, planning to

reassemble them on frames more suited to their specific tasks. During

rebuilding, we added an additional vertical thrust motor to each vehicle,

improved several task devices and made the motor and camera mountings

more secure. Rechristened Snoopy and Woodstock , the vehicles are now

ready for pool testing and competition.

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Contents

1. Design Rationale 1

2. Electrical Schematics 4

3. Description of At Least One Challenge 5

4. Troubleshooting 6

5. Future Improvements 7

6. Lessons Learned or Skills Gained 9

7. Use of ROVs in National Marine Sanctuaries 10

8. Acknowledgments 13

9. Budget and Expense Sheet 14

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1. Design Rationale

There are several key design features to the mission system we have

constructed. The most important of these features was the decision to

construct two ROVs to complete the array of tasks set out before us. There

are several advantages to using two ROVs rather than just one. First, each

ROV is simpler, because it has fewer tasks to complete. Second, the

smaller number of tasks per ROV allow for larger devices while

maintaining the general design of a small, highly maneuverable vehicle.

By having two vehicles completing tasks at one time, controlled by

separate drivers and independent control systems, less time is required to

complete as many mission tasks as possible. With seven tasks to

complete, time becomes an important consideration. (N.B. We received

off icial confirmation that having two ROVs, together operating under the

25-amp limit, i s allowed.)

ROV Snoopy ( l eft) and ROV

Woodstock (right)

Another notable feature

is the passive nature of most

of our task devices. By using

non-powered devices to

complete most tasks, we were able to limit current draw and remain

within limits even with two vehicles. For the patch placement, fish

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col lection, and bell identi fication, simple, non-powered devices complete

a task that would otherwise require a very complex powered device. For

the releasing of the towfish hook, dropping the tags, and the collection of

rocks, we could not think of any very reliable passive device, so these

three devices are actuated. With our effort to limit current draw, even

these devices are very simple, largely passive devices with a control led

trigger, relying on gravity and maneuvering to complete the remainder of

each task.

ROV Woodstock ’s tag-

dropping device is powered

by two solenoids, taken from

an old doorbell , wired in

parallel but with oppositely

facing diodes. When the

actuator DPDT switch is

flipped to the left, the left

solenoid pulls the core back,

releasing the left tag. When

the DPDT switch is fl ipped

to the right, the right tag is

released. On top of each tag

is a micro-Mag-Lite that

shines straight down. This

Mag-Lite shines a spotlight

over where the tag is supposed to land.

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Another powered

device is the rock-collection

system. After testing a

passive system which

consisted of a sharp scoop,

we concluded the ROV

Snoopy did not meet the

power requirements

necessary for reliable retr ieval of the rocks. Thus, an active system was

developed that use a bilge pump to act as a vacuum for rocks. The bi lge

pump just has i ts protective covering removed, and instead of one exi t for

water, a grill of holes were dril led on the side casing for water to exit.

This allows for greater water flow and no exertion of a lateral force by the

bilge pump. In addition, a chicken wire

covering protects the rock sample from

col lision with the bi lge pump’s propellors.

When the rock is retr ieved into the main

tube, the bilge pump is turned off so that the

rock can fall into a bottom pocket. Once the

ROV has resurfaced, a removable cap below

the bottom pocket is taken off for easy

removal of the rock sample.

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12 V( - ) ( + )25A Fuse (Provided to Competitors)

Left Thruster(Bilge Pump)

DPDT Switch

DPDT Switch

DPDT Switch

Right Thruster(Bilge Pump)

Vertical Thrusters(Bilge Pumps)

Left Thruster(Bilge Pump)

Right Thruster(Bilge Pump)

Vertical Thrusters(Bilge Pumps)

DPDT Switch

Note: Dotted line represents separationbetween the control box and the ROV itself,almost like an imaginary waterline.

Power Switch

A

A25A Ammeter

20A Fuse

PowerSwitch

DPDT Switch

Tag Dropper(Two Solenoids)

Hook Release(Hobby-Kit)

10A Fuse

DPDT Switch

12V DC Out (Camera)

12V DC Out (Camera)

25AAmmeter

( + ) ( - )

( - ) ( + )

2 SPDTSwitches

2 SPDTSwitches

2. Electrical Schematics

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3. Description of At Least One Challenge

One of the most challenging issues in constructing the ROVs was the

attempt to keep devices simple and passive. Oftentimes, outlandish ideas

are the f irst response to a complicated challenge, such as the seven

mission tasks. However, outlandish ideas are more complicated to build,

and, according to Murphy’s Law, more

likely to fail , while a simple device requires

a less intensive build and is less likely to

fai l . One of the best examples of simplifying

a complex idea was with the fish collection;

original ideas included forks that would lift

up and down picking up the fish, and even a

complicated arm was briefly considered.

However in the end, a simple pair of

parallel rods was our solution.

This simple device for collecting fish also meets our second design

goal of using passive devices. We tried to keep devices passive in order

to conserve current draw— with two ROVs, current draw was a constant

concern. Oftentimes a single motor could have made a task much simpler,

but we kept to our goal of passive devices, successfully limiting each

vehicle to only one powered device.

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4. Troubleshooting

The cameras we ordered claimed to be waterproof, so a shallow-

water test was done on one of the cameras.

However, the tested camera was not entirely

waterproof, proven by the fact it was not

operational the next day, and when the

camera was opened, much of the circuit

board was covered in rust. Therefore,

another camera was covered in sil icone glue

at all the seams, and was tested in deeper

waters. The camera was sti ll ful ly

operational afterwards.

Whenever a motor stopped working, connections were checked

using the probes of a multimeter. First a voltage was checked to see if the

motor was receiving any signals from the control box. If there was no

signal, then the tether and the control box

had to be checked. I f there was a signal,

then the leads of the motor were probed for

continuity. If there was no continuity, then

the shaft of the motor was manual ly forced

to turn to attempt to clean the brushes. If

that stil l did not work, the case of the

motor was opened to check the status of the

inside components. The motor was then

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cleaned and lubricated, or replaced if it was too corroded or damaged.

5. Future Improvements

In any engineering project, there are possibi lities for improvement.

This is true of our ROVs. One feature which needs improvement is

construction material for the frame. While

using PVC for the frame is cheap, durable,

and easy to modify, there are drawbacks.

The length of piping that goes into joints

varies widely; meaning that cutting out the

correct pipe lengths is dif ficult , if not

impossible. Due to considerations of tools

and budget, we plan to continue using PVC

while looking for other possible materials.

Another area for improvement is in the control system. While the

current rocker switches we use are suff icient, they do not allow analog

control. An analog joystick would allow improved control , through

integrated controls, and variable motor speeds. Further more such a

setup would easier to use as piloting the ROV becomes more like flying.

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ROV Woodstock ’s Control Box Layout

Greatest of all improvements would be the use of a fiber optic

control system. The tether could be reduced to a single power cable and

fiber optic cable. One power

cable means that there would

be little if any power lost in

tether. Smaller tether would

result in fewer restr ictions

for a maneuvering ROV. The

fiber optic cable could carry

as many sensory inputs as

necessary allowing it to be re-used year after year . Currently the tether is

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connected to the control box via DB9 connectors, which offer at least four-

pair of connections.

6. Lesson Learned or Skills Gained

The most important lessons learned during the completion of the

project were to begin earlier and to use more secure building materials.

In the past, we have used plastic cable-ties

to attach motors and task devices.

However, in modifying our vehicles since

regionals, we decided to use pipe brackets

to hold motors and devices. This makes the

propulsion more efficient due to reduced

vibrations, and makes the task devices

sturdier and more effective. We plan to

continue using this more professional

approach in future ROVs.

This year , we began meeting about six months before the regional

competition but did most our construction in the final three or four weeks

before competition. This was because we spent too much time earlier in

the project designing speci fic devices without real ly knowing the exact

dimensions of the tasks. All of this early brainstorming had to be revised

when we had more information. Also, we were designing primarily in

our heads and on paper, rather than with real objects. In the future, we

plan to work more with three-dimensional models in the early stages of

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design, and to build a functional vehicle for practice during the fal l .

Later in the project, when we have more information, we can bui ld the

actual vehicle with more knowledge and experience.

7. Use of ROVs in National Marine Sanctuaries

ROVs are used in National Marine sanctuaries to enhance the work

done by scientists. They take pictures of ocean li fe around to help us

understand what functions occur in sanctuaries and how they can be

protected. They are used to videotape ocean life or as l ive camcorders to

further aid the understanding and exploring of marine sanctuaries.

When there are unfavorable and hazardous diving conditions such

as during the night and exploring the ocean f loor, ROVs are very useful.

They can stay down for many hours since they are not limited to an

oxygen as a diver would be. ROVs have plenty of l ight and are very

maneuverable. They can hold a certain location for hours at di fferent

depths. More importantly, ROVs are used to collect biological and

geological samples and to understand and characterize coral reefs. ROVs

also measure distance, which helps scientists evaluate conditions at

certain depths and potential problems.

ROVs were deployed in the Olympic Coast National Marine

Sanctuary to explore the organism activities late at night on the ocean

floor. Side-scan sonar and multiyear bathymetry (high resolution seafloor

contour mapping) were among the instruments the ROV used. From this

expedition, scientists were surprised to discover a sand and cobble f loor,

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scattered with boulders. Brittle stars (pictured below) covered almost the

entire ocean floor. The data and images collected were used to predict

how rich the environment analyzed was. Scientists used this information

to compare it to other places in order to characterize the seaf loor

community.

(The image above is of bri ttlestars, which often gather on the soft

substrate.)

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The Phantom III S2 ROV (shown above) was about to be launched in

the Thunder Bay National Sanctuary. In this sanctuary lies over a

hundred shipwrecks. The ROV provided video documentation for the

understanding of preservation of submerged cultural resources. This

project was for outreach and educational purposes: the video was shown

to students, sparking interests in oceanography. The video greatly

fascinated students, and made them feel connected to the ocean, as if they

were actually in the ocean themselves. Also, the ROV documented the

settlement of the zebra mussels and round gobies, two invasive species.

In 1999, the locations of the spawning corals were observed. A ROV

was equipped with a video camera and skimmed the seafloor . A scientist

then used a multiyear bathymetry to track the ROV_s location. This was

the first time scientists were able to identi fy the location of the seafloor

features at the exact moment they were perceiving and videotaping them.

Sources:

NOAA Ocean Explorer: Sanctuary Quest

http://oceanexplorer.noaa.gov/explorations/02quest/sanctuaryquest.html

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CMG Multibeam Map Guides Sustainable Seas Exploration in Flower Garden Banks

National Marine Sanctuary

http://soundwaves.usgs.gov/1999/10/fieldwork.html

• NOAA Partnership Conducts Live Webcast from The Thunder Bay National Marine

Sanctuary and Underwater Preserve

http://www.nurp.noaa.gov/Spotlight%20Articles/underwaterweb.html

NOAA Ocean Explorer: Santuary Quest

http://oceanexplorer.noaa.gov/explorations/02quest/logs/jun16/jun16.html

8. Acknowledgements

We would like to thank Paul McGuinness for being our team

advisor, for being our supplier of tools and materials, and for keeping us

focused on the tasks at hand. Thanks to Peter Kerebruk from Draper

Laboratories for fitt ing propellers onto our thruster shafts. We appreciate

team graduate Thaddeus Stefanov-Wagner for bouncing our ideas back to

us and giving us feedback on our design. We would also like to thank the

Boston, MA Piledrivers Union and the Cambridge Public School

Department for their support of the team. Lastly, thanks to Nina

Alexander and Amanda Shing for giving us moral support and distracting

us when we got too serious and stressed, to Hummy Song, Paul Boudreau,

Catherine Liu, and Sara Gaynor for help with construction,

documentation and random comments, and to our parents for giving us

bui lding space and tolerating those late-night phone calls.

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9. Budget and Expenses

Expenses: McMaster (Tether) $46.00RadioShack (Cameras) $360.00Home Depot (Hardware) $150.00West Marine (Bilge Pumps) $100.00RadioShack (Control Box) $113.59Ace Hardware (Hardware) $50.00 $819.59 Funds: Existing from Last Year $500.00MATE $100.00School $300.00 $900.00

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