latis ii underwater remotely operated vehicle technical...

2010

Team Members:

Michel Bernier

B.S. Mechanical Engineering, University of Maine

Ryan T. Foley


Philip Rioux


Amelia Stech


Advisor:

Mohsen Shahinpoor, Ph.D., P.E.

Richard C. Hill Professor and Department Chair

Latis II Underwater Remotely Operated Vehicle Technical Report

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LATIS II TECHNICAL REPORT

ABSTRACT For the first time, a University of Maine

Mechanical Engineering Senior Capstone Design

group designed and built an underwater

remotely operated vehicle (ROV) and will

participate in the 2010 MATE International ROV

Competition. Four senior Mechanical

Engineering design students have worked on

preparing a prototype underwater ROV (Latis I)

and their final underwater ROV (Latis II) for the

competition. Missions included such tasks as

sensing and measuring sound waves, accurately

measuring fluid temperature, navigating

through an underwater cave and collecting

crustaceans and other materials from

underwater and returning them to the surface.

While Latis I provided much needed practice

and valuable insight into designing an

underwater ROV, Latis II was designed to

complete the missions outlined by MATE for the

competition. The UMaine ROV Team built two

identical four-degree-of-freedom (DOF) arms

with open-and-close grippers. To manipulate

the arms on the ROV the team also built two

control arms which provide feed-forward

control. Latis II has a custom-made upper body

structure machined from High Molecular

Weight Polyethylene (HMWPE) and a stainless

steel lower frame. There are six static thrusters

providing six DOF control, three cameras and a

holding net. Onboard control is achieved using a

Compact Rio (C-Rio) which receives signals from

a space navigator joystick and an Arduino

micro-controller that translates information

from the control arms.

TABLE OF CONTENTS Abstract ....................................................... 2 Budget/ Expense ......................................... 3 ROV Electronics ........................................... 4

Main Controller ....................................... 4 Thrusters ................................................. 4 Servos ...................................................... 4 Sensors .................................................... 4 Custom Circuit Boards ............................. 4

Surface Controls .......................................... 6 Main Controls .......................................... 6 Arm Controls ........................................... 6

Power Supply Box ................................ 6 Software ...................................................... 7 Design Rationale ....................................... 11

Missions ................................................. 11 TASK #1 – Resurrect HUGO................ 11 TASK #2 – Collecting Crustaceans ...... 11 TASK #3 –Sample New Vent Site ....... 12 TASK #4 – AGAR Sample .................... 12

ROV Design ........................................... 12 Frame..................................................... 12 Arms ...................................................... 13 Tether .................................................... 14 Thrusters ............................................... 14 Cameras ................................................. 14

Challenges ................................................. 15 Troubleshooting Techniques .................... 15 Lesson Learn/ Skills Gained ....................... 16 Future Improvements ............................... 17 Loihi Seamount ......................................... 18 Reflections................................................. 19 References ................................................ 20 Acknowledgements ................................... 20

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BUDGET/ EXPENSE

At the beginning of the 2009-2010 academic year The UMaine ROV Team predicted a budget of

$6,106.00 for the prototype and ‘start-up’ costs. For the competition ROV, the Team estimated a

budget of $5,337.13 with a travel budget of $6,554.00. In total, the estimated budget for the entire

project was $17,997.13. At the end of the 2009-2010 Design Year, the UMaine ROV Team spent a total

of $30,024.05 in preparing, designing, building, testing and competing in the MATE Competition. It is

predicted approximately 60.8% of the total cost went toward materials useable for next year’s ROV

Team at the University of Maine.

ITEM DESCRIPTION DISCOUNT TOTAL

1 Prototype (Latis I) Materials $0.00 $1,303.35

2 Competition ROV (Latis II) Materials $0.00 $2,039.36

3 Cameras $0.00 $497.42

4 Power Circuit Boards with Components $0.00 $401.54

5 Sensors (Temperature, Humidity, Sound, Thermistor) $0.00 $346.45

6 Thrusters and Drivers $3,600.00 $2,689.96

7 Servo Motors $0.00 $1,051.36

8 Tether Materials $0.00 $496.34

9 Outsourced Manufacturing $0.00 $4,967.69

10 Pilot Controls $0.00 $569.54

11 Computer and Monitors $0.00 $964.94

12 Power Converters $0.00 $838.36

13 Onboard Controller $5,795.70 $6,279.90

14 LabVIEW Software $4,699.00 $0.00

15 SolidWorks Software $396.00 $0.00

16 Travel Cases, T-Shirts and Shipping $0.00 $6,794.40

17 Water Tank and Tools $0.00 $783.44

Grand Total $14,490.70 $30,024.05

Table 1: 2009-2010 UMaine ROV Budget and Expense Sheet

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ROV ELECTRONICS

MAIN CONTROLLER

At the heart of Latis II is a National Instruments

Compact RIO controller (cRio). The cRio is most

commonly used for data acquisition and

automation control. The cRio on Latis II has

slots for four drop-in modules, of which three

are used. The team used two 9401 Digital

Input/ Output modules, as well as a 9205

Analog Input module. These modules are used

to link the cRio processor to its environment

through sensors and output devices.

THRUSTERS

Six BTD-150 Seabotix thrusters are used on Latis

II for propulsion. Three Sabertooth 2x10

electronic speed controllers are used to

regulate thruster power. Each Sabertooth

controls two thrusters.

SERVOS

The motion of each arm joint is provided by a

small hobby servo. Eight HS-7775MG Hitec

servos are used for the shoulders, elbows, and

grippers. Two HS-805BB Hitec servos are used

for the shoulder rotation joint. All of the servos

connect back to custom circuit boards in the

main enclosure for control and power signals.

SENSORS

To provide feedback on internal and external

conditions, Latis II is equipped with a variety of

sensors.

Phidgets Temperature and Humidity

Sensor Board to measure thermal

conditions inside the ROV enclosure

OMEGA Thermistor for measuring

external water temperature

H1a Aquarian Audio Hydrophone for

measuring external sound sources

CUSTOM CIRCUIT BOARDS

To make it easier to interface to the cRio

modules, three custom printed circuit boards

(PCBs) were designed and manufactured. Each

PCB connects to its cRio module through a

ribbon cable, and connects to various devices

through three-conductor cables commonly

found in radio-control hobby electronics.

THRUSTER BOARD

The Thruster Board breaks six digital output

channels from a 9401 module on the cRio into

three-pin headers for the Sabertooth units to

plug into. The remaining two channels are used

to control the gripper servos. Each servo pulls

power from the 5V supply through a PCB-

mounted 3A fuse.

Figure 1: Thruster PWM Board

To work with this PCB, the 9401 module on the

cRio is configured for pulse-width-modulation

(PWM) output. Each channel produces a square

wave with a duty cycle proportional to the

desired speed.

A resistor-capacitor (RC) circuit is used to filter

the pulse with modulation (PWM) signal into an

analog signal for the Sabertooth. The servos

require an actual PWM signal, so no filtering

circuit is used.

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ANALOG SENSOR BOARD

The Analog Sensor PCB breaks eleven analog

input channels out to three-pin headers for easy

interfacing with sensors.

Figure 2: Analog Sensor Board

Almost all sensors used on Latis II return a 0-5V

analog signal. The thermistor used for external

temperature measurements is a resistive

sensor, meaning it varies in electrical resistance

based on the surrounding temperature. Since

the 9205 analog input module on the cRio can

only measure voltage, additional circuitry was

required on the board.

Figure 3: Thermistor Circuit

As shown in the schematic in Figure 3, the cRio

measures the voltage across a 10K resistor.

Using Ohm’s Law, the current passing through

the resistor can be calculated.

𝐼10𝐾 =𝑉10𝐾10𝐾Ω

Using Kirkoff’s Current Law, the current through

the thermistor is the same as what passes

through the 10K resistor. Then, Kirkoff’s

Voltage Law shows that the voltage across the

thermistor is the difference between the 5V

supply and the voltage across the 10K resistor.

This yields a final thermistor equation shown

below.

𝑅𝑇ℎ𝑒𝑟𝑚𝑖𝑠𝑡𝑜𝑟 =5𝑉 − 𝑉10𝐾

𝐼10𝐾

ARM SERVO BOARD

The Arm Servo Board connects to the second

9401 digital I/O module, distributing its

channels into eight three-pin headers for the

arm servos. Each servo draws its power from

the 5V bus through a PCB-mounted 3A fuse.

Figure 4: Arm Servo Board

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SURFACE CONTROLS

MAIN CONTROLS

Latis II is capable of six degrees of motion; three

axes of translation and three axes of rotation. A

3D Space Navigator was used to help make the

propulsion control intuitive for the pilot. The

3D navigator is capable of motion in the same

six axes that Latis II is, so the pilot simply moves

the navigator manner that he/ she would like

Latis II to move. The 3D navigator allows one

handed control of the ROVs motion. Having

one hand free, the pilot can use the mouse or

keyboard to interact with the LabVIEW program

dashboards on the computer.

ARM CONTROLS

Latis II features an intricate pair of arms, each

one capable of four degrees of freedom.

Controlling these arms through joysticks or

sliders on the computer screen would be

complicated and require a great deal of practice

for the arm operator. Taking inspiration from

arm controls seen in the FIRST Robotics

Competition, Latis II has a set of control arms on

the control board. These control arms contain

three potentiometers for the lower joints, as

well as a mini-joystick for control of the wrist

and gripper. As these arms are moved to

various positions, the software adjusts the

servos on Latis II to match the angles read from

the sensors on the control arms.

The sensors are connected to an Arduino Mega

controller, which sends the values to LabVIEW

via serial communication. This style of arm

control is significantly more intuitive for the

operator, greatly reducing practice time

required to become skilled at using the system.

Figure 5: Control Arms

POWER SUPPLY BOX

An acrylic box was designed and fabricated to

hold all of the power converters, video

convertors, fuses, switches, camera and power

connectors, and the main 40A breaker while

supplying continuous air circulation to all the

components. Three DC-DC converters step the

supplied 48V down to 24V, 12V, and 5V for the

ROV. The power supply box also contains all

the connections for the video lines that allow

the tether to be plugged in on one side and the

VGA monitor wires run out the other. With

their power box design the UMaine Team can

be set up and ready to compete with their ROV

in less than a minute.

Figure 6: Power Supply Box

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Figure 7: ROV Pool-Side Electronics

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Figure 8: Onboard ROV Electronics

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SOFTWARE

LATIS II

The cRio controller on the ROV is programmed

using National Instruments LabVIEW software.

LabVIEW is a graphical programming language

that allows users to create programming code

through control block diagrams rather than

traditional line code found in BASIC or C. Since

most of the team did not have any experience

with C or other typical controller programming

languages, the graphical format of LabVIEW

allowed the team to focus their efforts on the

actual content of the program, rather than

learning the syntax.

MAIN HOST AND DASHBOARD

The core component of the software is the main

host program (called a virtual instrument, or

VI). The main host contained the code for all of

the inputs and outputs for the ROV, including

sensors, thrusters, and the arms. The front

panel of this VI contains displays and indicators

for many of the ROVs vital functions.

Figure 9: LabVIEW Dashboard

VENT MISSION SUB-VI

To increase the modularity of the system, the

vent mission code is broken out into a sub-VI.

When performing this mission, the pilot presses

a button on the dashboard to load this program

separately. The program then allows the pilot

to record the three temperatures, chart the

data, and show the judge before closing the

program. Having this code as a sub-VI helps

free up space on the main dashboard for other

indicators. This setup also allowed the team to

create and test the code for this mission before

any of the code for the actual ROV was created.

Figure 10: Vent Mission Dashboard

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Figure 11: Latis II Software Flowchart

LATIS II

Read 3D

Navigator

Convert 3D navigator signals

to individual thruster values

Write PWM values

to thrusters

Read serial

string from

Arduino

Break serial string into

individual sensor values

Write duty cycles

to arm servos

Convert sensor values to arm

servo duty cycles

Read sensor

voltages from ROV

Convert sensor voltages to

real-world values

Update dashboard displays

for all sensors

Update thruster power level

displays on dashboard “VENT”

button

“HUGO”

button

VENT Mission

subroutine

HUGO Mission

subroutine

END

“Stop”

button

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DESIGN RATIONALE

MISSIONS

After establishing that the UMaine ROV team

could successfully build, program and operate

the prototype, Latis I, the team began the

design process to create a new ROV specifically

designed for the MATE ROV Competition. The

team focused on compactness, efficiency,

simplicity, and manufacturability in the final

design. The following is a short description of

the design rationale followed for each task

appointed by MATE.

Figure 12: Prototype ROV, Latis I

TASK #1 – RESURRECT HUGO

The first mission requires the ROV to locate an

area of seismic activity, release the High Rate

Hyrdophone (HRH) from the elevator, and

install it at that spot. Next, the ROV must open

the port on HUGO’s junction box and insert the

HRH’s cable. To accomplish these tasks, Latis II

has a hydrophone installed on the front of the

body which can detect sound waves. The

LabVIEW dashboard provides a graphical display

of the sound waves underwater and gives a

numeric value of the frequency. The ROV also

has opposing four degree-of-freedom arms

outfitted with grippers. This will allow the ROV

to remove both pins from the HRH

simultaneously and move it to the location

emitting the sound waves on the pool floor.

Latis II has three cameras installed to give the

operators multiple views of the arms and any

objects the ROV needs to grab or manipulate.

These multiple viewing angles allow the

operator to successfully complete this task. The

grippers were designed specifically to hold the

elevator and HRH frame so that the ROV is

stable as it removes the HRH.

TASK #2 – COLLECTING CRUSTACEANS

The mission involves entering an 80cm by 80cm

cave, collecting crustaceans, and returning

them to the surface. It is with this task in mind

that the ROV Team designed such dexterous

arms. The increased flexibility of the arms

allows them to be particularly useful in this task

as the ROV will only have to rest on the bottom

of the pool as the arms do the work. Two LED

lights installed on the front of the ROV allows

the operator to clearly see the inside the cave.

A retractable net affixed to the front of the

skids makes a handy place for storing

crustaceans that will be brought to the surface.

Having the net on the front of the ROV provides

storage space for the crustaceans so that no

time has to be wasted returning to the surface

to retrieve them. The overall size of the ROV

was decided when designing for this task as it is

the only one with a size limit. The dimensions of

the ROV are 43cm wide, 60cm long and 29cm

tall. This allows the ROV to maneuver freely

through the cave.

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Figure 13: Arms Collecting a Crustacean

TASK #3 –SAMPLE NEW VENT SITE

This task requires Latis II to measure the

temperature of the venting fluid in three

different locations along the chimney height

and collect a sample of vent spire to return it to

the surface. A waterproof thermistor was

installed on the right gripper to record the

venting fluid temperature. This task provided

another reason for the increased dexterity of

the arms for the gripper needs to clamp on the

tip of the vent which is at a 45deg angle and

hold on until the temperature value is displayed

on the computer screen. By having the

thermistor situated at the end of the gripper

and allowing the gripper to hold on to the vent,

the ROV will be stabilized as the thermistor

reads the fluid temperature. Furthermore, the

net attached to the front of the ROV will allow

room to store the vent sample that needs to be

returned to the surface.

TASK #4 – AGAR SAMPLE

This mission task requires Latis II to collect a

sample of a bacterial mat and return it to the

surface. A special AGAR sampling tool was

designed using PVC pipe and fittings to collect

the proper amount of bacterial mat. The tool

relies on suction power and the ability of the

arms to break the surface tension of the AGAR.

The depth of the AGAR sample tray was taken

into account such that the diameter of the PVC

device was the only adjustable factor in

collecting the proper volume of AGAR. The

design allows for the tool to simply be pushed

straight into the AGAR and then pulled out with

the AGAR held by suction inside the tool. The

device and AGAR fit in the net on Latis II to

prevent the extra trip to the surface. Through

testing, AGAR was found to hold its shape and

not disintegrate when collected so the holding

net could be made of simple window screening

and no special alterations were required.

ROV DESIGN

The ROV was designed with buoyancy, strength,

size, dexterity, maneuverability and stability in

mind. The overall idea incorporates six simply

mounted thrusters, two identical 4 DOF arms

with open-close grippers, three cameras for

vision, a hydrophone and a thermistor for

measuring sound and temperature respectively.

FRAME

The ROV frame was one of the most highly

discussed components for the second semester.

While the simple design of the prototype with

its cylindrical water proof enclosure surrounded

by a metal frame was effective, it wasted

valuable space for electronics and was difficult

to mount components to. It was finally agreed

upon to make the upper structure both

waterproof and structural so that there was no

need for both, square for ease of fabrication

and mounting, and made out of light plastic for

buoyancy and strength. The bottom plate and

lower skids were made of stainless steel for

weight and resistance to corrosion in water.

Constructing the lower portion of the ROV out

of heavy stainless steel and the top section out

of buoyant plastic creates a pendulum effect in

the water causing the ROV to always tend

toward an upright attitude and increases its

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stability. Since the ROV is bottom heavy, the

primary thrusters for forward, backward,

turning, and strafing motion were mounted on

the underside, allowing Latis II to maneuver

easier since the thrusters’ force is applied close

to the center of mass. The skids also protect the

thrusters from being damaged and provide a

solid stand for the ROV to sit on the pool floor.

The ROV was tested in a tow tank and

coefficient of

Figure 14: Main Frame Parts

ARMS

Many different arm design ideas were

considered during this part of the design

process. The team eventually decided on using

Hitec 7775MG digital hobby servos for the

majority of the arm linkages, and Hitec 805BB

analog high toque servos for the heaviest joint-

the shoulder rotation. Most joints utilized a

chain and sprocket power transmission design

not only for its simplicity and effectiveness, but

also for the ability to use sprocket ratios to

increase the power at any given connection.

The range of motion for each link was decided

and the corresponding sprocket ratio calculated

to reach that desired range from the 180deg

range of the servos. Since the range was always

less than 180deg the torque available at the link

would always increase proportional to the

range decrease. The servos were sized for their

power, size, and weight. To waterproof the

servos they were dipped in Plastic Dip. A

greased O-ring was installed between the servo

case and the servo sprocket to protect the

opening where the spline enters the case.

Figure 15: Servo Waterproof Testing

Lightweight plastics were utilized wherever

possible for easier manufacturability and their

high strength-to-weight ratios. HMWPE was

used for the larger pieces of the arm and the

connecting pins; a quarter inch thick PVC plate

was used for the main structure of the links,

and Teflon (PTFE) was used for bushings

between the connecting pins and links as a soft

slippery interface to reduce friction. All

connections were made using press fit sizing to

reduce the need for heavy metal fasteners. The

grippers were designed using a rotation-to-

linear linkage system and the grippers

themselves were dipped in Plastic Dip to add

extra grip.

Figure 16: Latis II Arms

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TETHER

The tether supplies Latis II with power and

communication. It is composed of four 10g

power cables, one 35mm coaxial audio cable, 3

coaxial camera cables with BNC connectors and

incorporated power, and a single CAT5e

Ethernet cable. The team designed the tether to

be neutrally buoyant for the first 15 feet to

allow Latis II to maneuver without much tether

drag. This was extremely important considering

the ROV needs to travel freely through the

underwater cave.

THRUSTERS

The team decided to use six high quality

thrusters from Seabotix for their propulsion

system. The team chose these because of the

frequency with which MATE ROV Competition

Teams have used them in the past and Seabotix’

discount to MATE Teams. While four thrusters

were tested on the prototype, six thrusters

were installed on Latis II to provide extra power

and maneuverability. The positioning of the

thrusters provided maximum dexterity for the

ROV to move in all six dimensions with ease.

Figure 17: Thruster Arrangement

Cost, voltage and amperage were the three

main driving factors for the team’s decision to

use three Dimension Engineering Sabertooth

2X10 motor controllers to drive the thrusters.

CAMERAS

Vision was a high priority for the team as it

allows for smoother operation by the pilot and

arm operator. Two cameras are mounted on

the top of the ROV and can be infinitely

adjusted in all directions. The third camera is

mounted inside the ROV and looks through a

window directly at any task that the arms may

be completing and can also see the attitude of

the retractable net. The two waterproof

cameras on the outside of the ROV have wide-

angle lenses allowing them to see as much of

the playing field as possible, while the indoor

camera has a slightly smaller aperture giving it a

more defined and detailed view of the

immediate front of the ROV.

Figure 18: Control Monitors and power supply box

Two computer monitors are used to provide

views from all three cameras by way of a video

switcher, while a third is dedicated to the

LabVIEW dashboard.

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CHALLENGES

One of the most difficult challenges faced by

the UMaine Team was preparing the ROV to

operate in a submerged environment. Due to

the extensive electronic systems both inside

and outside the electronics enclosure, excellent

waterproofing processes were essential. To

address this challenge, initial testing was

conducted on prototype, Latis I. The

information gained from these tests influenced

the final ROV design. For example, difficulties

with small leaks through the waterproof

connectors led to a final design with a

permanent wire configuration and only

installing a single removable part to access the

sealed enclosure. Furthermore, sealing

compounds such as potting epoxy were used

more on Latis II because of the hardening

capabilities not observed when using silicone or

polyurethane.

Another challenge faced by the team was

dealing with conflicting opinions within the

group regarding the steps to address a technical

issue or the particular technical issue itself. It

became obvious to the team that a process for

resolving such conflicts would increase the

productivity while avoiding interpersonal

aggravations. To solve this problem it was

agreed upon that testing would be conducted,

when possible, on each idea to determine its

viability. The criterion for selection was based

on design parameters for our project such as

cost, reliability, ease of implementation, and

integration into existing systems. This process

allowed a comparison between the ideas of the

individual, and the goals of the team, usually

resulting in one idea that best fit the situation

at hand.

Finally, one of the biggest challenges was

manufacturing the parts for Latis II. After

spending more time and effort than anticipated

on Latis I it was decided early on in designing

Latis II that the team should outsource

manufacturing responsibilities to a company

that specializes in the task. This however did

not work well due to the slow turn-around time

of the parts and frequent mistakes made by the

manufacturing company. To solve this problem,

the team decided to learn how to operate the

Computer Numerically Controlled (CNC)

machine available in the lab and manufacture

some of the simpler parts. The team fabricated

the remainder of the parts needed to finish the

ROV, control arms and power supply box.

TROUBLESHOOTING TECHNIQUES

To gain some knowledge and experience that

the UMaine ROV Team could later call upon

when troubleshooting issues on Latis II, the

team designed and constructed their prototype

Latis I in the fall of 2009. From this first attempt

the team gained valuable insight into the things

that may go wrong in the future.

WATERPROOFING

In designing Latis I the team decided to use

factory-made water proof electrical connectors.

However, finding such connectors at the 40A

current rating was problematic. Furthermore,

the waterproof connectors finally purchased

ended up being the weakest link in the entire

electronics enclosure for Latis I. After weeks of

trying different techniques such as greasing the

O-rings of the connectors, tightening the

connectors more than the specified torque, and

even creating a positive pressure inside the

electronics compartment, the team was still

16


battling leaks. Hours of research was conducted

into finding better waterproof connectors.

When searching for connectors finally failed to

produce anything useful and legally sold in the

US, the team switched tactics and decided to

run the wires through air fittings which were

then tapped into the walls of the ROV body.

When the wire was sealed into this fitting and

the fitting threaded into the body, a water tight

seal was made and still allowed for the fitting

and component to be removed if necessary.

PROGRAMMING

By using the NI C-rio early on in the prototype

process the UMaine ROV Team was able to

encounter and fix as much of the programming

bugs as possible before beginning work in the

more complicated Latis II. Troubleshooting the

ROV control program involved either consulting

the team’s resident LabVIEW expert or

contacting the technical support provided by

National Instruments. With both of these

resources, the team was able to effectively

diagnose and solve significant programming

problems.

By far the most commonly used

troubleshooting technique was teamwork.

Working as a team allowed the most productive

use of time and netted the best results. Once

ideas were considered and then decided upon

the problem usually was solved by utilizing

other internal and external resources.

LESSON LEARN/ SKILLS GAINED

The problem with manufacturing that the team

learned is one that is undoubtedly inherent in

any design project and definitely provides room

for new skills to be gained. The lesson learned is

when relying on a company to produce vital

components, it is critical that the team monitors

the progress closely to avoid delays. If there are

problems, the team can decide early on what

actions need to be taken to resolve the issue.

As noted before, having learned from the time

needed to complete the parts for Latis I, the

team decided to send out Latis II parts to a third

party. The company, however, was unable to

deliver the parts as scheduled, or to the

specifications requested. This left the ROV team

with less material, money and time with which

to troubleshoot and complete their design.

Fortunately, there were good results from this

situation. The team stepped up to the plate and

took control of their product. Team members

worked day and night on the manual milling

and turning machines as well as the CNC. Parts

were retrieved from the manufacturer and

finished in the team’s lab. Team members

learned how to machine parts and to re-

fabricate already manufactured components.

Time-management became even more of a

priority as the team had even less time than

anticipated so they worked to gain lab access

during the nights and weekends.

In all, the team learned a valuable lesson in

taking control of their own design and gained

skills in machining, quality control, and time

management. Furthermore, the team gained

skills in diplomacy and professional

correspondence in working with the

manufacturing company to fix the problem.

Through teamwork and dedication, the UMaine

ROV Team was able to overcome the problem

and still produce a quality product in the time

available for the project.

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FUTURE IMPROVEMENTS

Throughout the entire design process the ROV

Team had to continuously change, alter and in

some cases completely remove or disregard

design components and ideas. Some of these

ideas, if they had been followed through, could

have made great designs. The following are

some design ideas the team would like to see

either pursued and integrated or improved

upon.

PROPULSION

Early in the design of the prototype the team

battled with designing the best propulsion

system for the ROV. Ideas ranged from belts

and flippers to hydraulics and pneumatics. One

idea that continuously surfaced, however, is

that of dynamic thrusters. With dynamic

thrusters, the same thrusters from Seabotix

could be used but instead of being statically

mounted to the body of the ROV they would be

mounted to rotatable plates such that they

could turn up to 360deg. This would allow a

single thruster to control at least two axis of

motion instead of just one when statically

mounted. Servos or any kind of motor

electrically driven or otherwise could be used to

rotate the thruster. The team would be able to

literally double their effectiveness with each

thruster and therefore cut the number of

thrusters, and motor drivers in half. The

downside of this is making the device that

would have to turn the thruster and then

integrating the extra control specifications into

the control program.

WATERPROOFING

Being one of the most, if not the most, difficult

problems plaguing the ROV team;

waterproofing techniques and design could be

improved. If the design had taken into account

more water tight compartments and less thru-

wall connections the waterproofing would have

been much easier. Furthermore, using less

electronics would also help in this respect (i.e.

hydraulic or pneumatic propulsion/power

system that is already inherently waterproof).

KEEP IT SIMPLE STUPID (KISS)

Even with the team’s best efforts to try and

make the design as simple as possible without

compromising function, the project still proved

to be far too complicated to complete in the

time allotted and with the people and resources

available. The team would like to see future

teams drastically cut down on the complexity of

the manufactured parts and the overall design.

Although many pre-made parts were

researched and considered for the ROV design,

a huge number of components still had to be

custom fabricated. Taking less time and effort

to make custom parts would leave more time to

practice with the ROV and prepare it for

competition.

18


LOIHI SEAMOUNT

The Loihi seamount is Hawaii’s youngest

underwater volcano located 30 km off the

southern coast of the Big Island. Rising more

than 3,000m above the sea floor, it is taller than

Mt. St. Helens was before its catastrophic

eruption in 1980. However, with the peak of the

seamount being a thousand meters below the

surface, exploration of the area has not been a

simple process. In 1996, a large earthquake

swarm at the seamount brought new attention

to the area. Researchers found evidence that

Loihi had erupted during the earthquake. This

was the first ever confirmed historical recording

of the seamount’s volcanic activity. Scientific

communities changed their view of Loihi from

that of a dormant seamount to an active

undersea volcano.

Figure 19: Digital Terrain Model of Loihi

Research of the Loihi seamount has been

conducted in large part by the University of

Hawaii’s Undersea Research Laboratory (HURL),

operated through the School of Ocean and

Earth Science and Technology (SOEST). The

Hawaii Undersea Geo-Observatory (HUGO) was

developed to record seismic activity, sound

within the water, and pressure changes. As an

automatic observatory, Hugo’s information is

sent through a fiber optic cable along the ocean

floor to a seaside station. Information is sent

from there to the University Hawaii for analysis.

Professor Fred Duennebier from Hawaii’s

School of Ocean and Earth Science and

Technology was the project leader for the Hugo

venture.

Figure 20: HUGO

When contacted by our team, he offered some

updated information about Hugo’s current

status. The cable to HUGO developed a short to

sea water about 6 months after it was installed.

The observatory was later recovered by JASON

in 2004 and has now been reconfigured for re-

installation at the ALOHA Cabled Observatory

north of Oahu.

Projects like HUGO and the ALOHA observatory

continue to be vital assets for researching and

exploring the vast ocean realms.

19


REFLECTIONS

MIKE BERNIER

As team leader/manager I feel that I had some

of the greatest responsibilities of the team. I

learned a lot from pushing myself as a leader

and as an engineer. This was a very time-

consuming and resolve-testing project that

brought out some of the best and worst in me

as a leader and I applaud my team for taking

both with acceptance and criticism. I can only

hope to take what I have learned over these

past months and apply it to everything I do in

my professional career to come. I would also

like to thank all of our supporters, advisors,

family and friends in their contributions of time

and resources to our project.

RYAN FOLEY

Working on the electronics and programming of

the ROVs was a rewarding experience. After

seeing many control styles through other

robotics competitions, I was thrilled that the

team was able to implement the feed-forward

control arms. Not being limited to a certain set

of allowable parts, as is the case in other

competitions I have been a part of, was a

unique experience. Being able to research,

compare, select, and implement a variety of

parts and systems was good practice for real-

world engineering. Working on the ROV was a

rewarding opportunity to work on a robotics

project that was out of my comfort zone.

PHILIP RIOUX

Learning the process of integrating software

with electrical components, and hardware, has

been my greatest professional accomplishment

of the Latis project. Understanding the entire

process allows me to design the hardware with

the software in mind. I am grateful to the MATE

organization for offering me, through the ROV

competition, a venue to grow my understanding

of the design process, as well as develop many

new technical skills that will serve me well in my

career for years to come.

AMELIA STECH

Establishing the first ROV team from the

University of Maine has been rewarding and

challenging. Having no previous experience in

robotics, machining and programming, working

on the Latis project expanded my knowledge

tremendously. I focused on the electrical

components of the ROV and was able to gain a

hands-on-experience in what goes on to

communicate with the main components.

Documenting everything that was considered

and done showed to be a helpful task. I am

proud to be a part of one of the hardest

working and dedicated capstone teams which

set a solid foundation for future MATE

Competitions.

20


REFERENCES

School of Ocean and Earth Science and Technology: http://www.soest.hawaii.edu/SOEST_News/News/SOESTinthenews2002.htm) Hawaiian Center for Volcanology http://www.soest.hawaii.edu/GG/HCV/loihi.html Figure 19 Photo Courtesy of: http://oceanexplorer.noaa.gov/explorations/02hawaii/background/plan/media/pearl_hermes_atoll.html ) Figure 20 Photo Courtesy of: Professor Fred Duennebier

National Instruments

ACKNOWLEDGEMENTS

The UMaine ROV Team would like to thank everyone who helped us with this project. Art Pete David Morrison Department of Mechanical Engineering Justin Poland Karen Fogarty Mohsen Shahinpoor Neal Greenberg Patrick Bates Professor Fred Duennebier Victoria Blanchette 2011 ROV Team

Figure 21: 2010 UMaine ROV Team

http://www.soest.hawaii.edu/SOEST_News/News/SOESTinthenews2002.htm

http://oceanexplorer.noaa.gov/explorations/02hawaii/background/plan/media/pearl_hermes_atoll.html

http://oceanexplorer.noaa.gov/explorations/02hawaii/background/plan/media/pearl_hermes_atoll.html

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