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Abstract

Subsea geological investigations are important to the development and progression of offshore structures including natural resource and alternative energy exploitation. Current research techniques involve surface-based procedures which are expensive and ineffective. The goal of this undergraduate project, in collaboration with The Ryan Beaumont Corporation, is to develop a more efficient process to acquire information on seafloor and riverbed composition.

This report includes the parameters and solutions, as well as the process and theory, behind every detail that is integrated into the design. The full-scale device is designed to house and transport geotechnical equipment to the seafloor to perform rock and soil investigations. The structure’s frame is able to withstand and counteract any forces or vibrations created by the testing equipment. By utilizing ballast pods and a control system, the stability of the platform is monitored during ascension and descension maneuvers. The autonomous control system allows the structure to determine its current orientation and make any necessary adjustments.

A prototype model was constructed to represent the physical properties of the device including size, weight, and performance criteria. Various stability experiments were performed on the prototype, the procedures and results of these tests are also included in this report.

Contributions

Thomas Allain: Design Concept Process (Ballast), Recommendations for Future Designs, Website

Paul Amsden: Purpose, Overall Design Description, Design Concept Process (Frame)

Ethan Gray: Design Concept Process (Stability & Controls), Conclusions

Brady Jacques [Lead Writer]: Scope, Design Concept Process (Stability & Controls), Design Testing & Evaluation,

Recommendations for Future Designs Erik Medina: Design Concept Process (Frame), Project Poster

Matthew Storgaard: Design Concept Process (Stability & Controls), Website

Matthew Waldroup: Abstract, Design Concept Process (Ballast)

Table of Contents:

1 Introduction ............................................................................................................................. 1

1.1 Purpose .......................................................................................................................................... 1

1.2 Scope of Full-Scale Model Design ............................................................................................... 2

1.3 Scope of Prototype Design ............................................................................................................ 2

2 Overall Design Description ..................................................................................................... 3

2.1 Frame ............................................................................................................................................ 3

2.2 Ballast Tanks ................................................................................................................................. 4

2.3 Air System .................................................................................................................................... 4

2.4 Control System .............................................................................................................................. 4

3 Design Concept Process .......................................................................................................... 5

3.1 Overview ....................................................................................................................................... 5

3.2 Full-Scale Design .......................................................................................................................... 6

3.2.1 Frame .................................................................................................................................... 6

3.2.1.1 Material Selection for Full-Scale ...................................................................................... 7

3.2.1.2 Full-Scale Pontoon Arm Design ....................................................................................... 7

3.2.2 Ballast Design ....................................................................................................................... 7

3.2.2.1 Sizing the Full-Scale Ballast Tanks .................................................................................. 8

3.2.2.2 Material Selection for Full-Scale Ballast Tanks ................................................................ 8

3.2.3 Stability & Control System ................................................................................................... 8

3.3 Prototype Design ......................................................................................................................... 10

3.3.1 Frame .................................................................................................................................. 10

3.3.1.1 Sizing the Prototype ........................................................................................................ 10

3.3.1.2 Material Selection for Prototype ..................................................................................... 10

3.3.1.3 Prototype Pontoon Arm Design ...................................................................................... 10

3.3.2 Ballast Design ..................................................................................................................... 11

3.3.2.1 Sizing the Prototype Ballast Tanks ................................................................................. 11

3.3.2.2 Material Selection for Prototype Ballast Tanks .............................................................. 11

3.3.2.3 Airflow System ............................................................................................................... 11

3.3.2.4 Fabrication & Installation ............................................................................................... 12

3.3.3 Stability & Control System ................................................................................................. 13

3.3.3.1 Stability of the Prototype ................................................................................................ 13

3.3.3.2 Equipment and Software Selection ................................................................................. 14

3.3.3.2.1 Software .................................................................................................................... 15

3.3.3.2.2 Microcontroller ......................................................................................................... 15

3.3.3.2.3 IMU Digital Combo Board ....................................................................................... 15

3.3.3.2.4 Power Supply ............................................................................................................ 16

3.3.3.2.5 Relay ......................................................................................................................... 16

3.3.3.3 Programming ................................................................................................................... 16

3.3.3.3.1 Autonomous Control ................................................................................................. 17

3.3.3.4 Installation ....................................................................................................................... 18

3.3.3.4.1 Autonomous Control Wiring..................................................................................... 18

3.3.3.4.2 Switchboard Wiring .................................................................................................. 19

3.3.3.4.3 Switchboard Control Box .......................................................................................... 20

3.3.3.4.4 Solenoid Valve Mount .............................................................................................. 20

3.3.3.4.5 Dry Box ..................................................................................................................... 20

3.3.3.5 IMU Calibration .............................................................................................................. 21

4 Final Design Testing & Evaluation ....................................................................................... 21

4.1 Stability Testing .......................................................................................................................... 21

4.1.1 Introduction & Objectives ................................................................................................... 21

4.1.2 Experimental Setup ............................................................................................................. 22

4.1.3 Results ................................................................................................................................. 23

4.2 Submersion Testing .................................................................................................................... 23



4.2.3 Results ................................................................................................................................. 25

4.3 Draft and Steady-State Keel Evaluation ..................................................................................... 25



4.3.3 Results ................................................................................................................................. 26

4.4 Heave & Roll Displacement Testing .......................................................................................... 26



4.4.3 Results ................................................................................................................................. 27

5 Conclusions ........................................................................................................................... 28

6 Recommendations for Future Designs .................................................................................. 29

6.1 Improvements in Design ............................................................................................................. 29

6.1.1 Pneumatic Arms .................................................................................................................. 29

6.1.2 Ballast Tanks ....................................................................................................................... 30

6.1.3 Dry Box ............................................................................................................................... 30

6.2 Design Innovations ..................................................................................................................... 30

6.2.1 Thrusters ............................................................................................................................. 30

6.2.2 Liquid Level Sensors .......................................................................................................... 30

6.2.3 On-Board Optics ................................................................................................................. 31

7 List of References .................................................................................................................. 31

8 Appendices ............................................................................................................................ 31

Table of Figures:

Figure 1: Overall Design Arrangement ......................................................................................................... 3 Figure 2: Air supply system arrangement ..................................................................................................... 4 Figure 3: The controls dry box and breadboard-relay wiring setup .............................................................. 5 Figure 4: The full-scale model of the device generated using SolidWorks .................................................. 6 Figure 5: Transverse righting arm & hydrostatic property curves of the full-scale design ........................... 9 Figure 6: Diagram of the airline system ...................................................................................................... 12 Figure 7: Left to right from top; solenoid valves, 4-way manifold, T-valve, air pressure regulator, compressed air tank, and hose bundle ......................................................................................................... 13 Figure 8: Transverse righting arm and hydrostatic property curves formulated using GHS ...................... 14 Figure 9: The Arduino Mega microcontroller and 6-DOF IMU combo board ........................................... 15 Figure 10: The Elenco 20VDC power supply and Kyotto DC solid state relay ......................................... 16 Figure 11: The LabVIEW virtual instrument created for autonomous stability control ............................. 17 Figure 12: A schematic of the autonomous control system wiring ............................................................. 18 Figure 13: A schematic of the manual switchboard control wiring ............................................................ 19 Figure 14: Fiberglass manual switchboard control box .............................................................................. 20 Figure 15: Calibration curves for the inertial measurement unit ................................................................ 21 Figure 16: Schematic of the wave tank experimental apparatus ................................................................. 22 Figure 17: The device during testing in the Wallace Pool, and the experimental setup ............................. 24 Figure 18: An illustration of the draft (T) of a floating vessel .................................................................... 26 Figure 19: Impulse application points for heave and roll displacement ..................................................... 27

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1 Introduction 1.1 Purpose

The Ryan Beaumont Corporation, in conjunction with a team of mechanical engineering students from the University of Maine, is working to develop a submersible geotechnical investigation device called Triton.

Currently, surfaced-based techniques are used in seabed investigations. A surface vessel with a moon pool will typically use a long pipe as a borehole casting between the vessel and the seabed. However, there are several drawbacks to this means of investigation:

The amount of time required to mobilize equipment and perform the investigation, which can take upwards of 3 months

High associated cost The goal of the senior capstone Triton project was to offer solutions to these and many other

problems encountered in surfaced-based investigations. Figure 1 summarizes some problems and proposed solutions.

Table 1: Investigation issues and associated solutions that Triton hopes to offer [1]

Triton will be primarily used to assist in the development of offshore renewable energy sites for Maine Hydrokinetic (MHK). The advantages of offshore wind and tidal energy sources are many:

Offshore energy is more predictable than other renewable sources

These sources are emission-free

Many MHK technologies are not visible or audible from shore The total market for tidal and wave renewable energy is worth up to $746.6 billion in the

period of 2010-2050, with the market reaching $64.9 billion per annum in 2050 (Carbon Trust, 2011). For a number of remote communities located near MHK resources, the growth opportunity is enormous.

P a g e | 2

1.2 Scope of Full-Scale Model Design

The student design team set out to come up with a preliminary design of a completely submersible device that is limited to accommodating for drilling, cone penetrometer tests, and sampling in underwater geotechnical investigations. The team then tested the viability of the design by assembling a scaled prototype of the device and running various performance tests.

For the safety of all personnel involved, the submersible is designed to be used in calm ocean conditions, and therefore was designed to a one year storm as a conservative limit. Except for the forces and moments produced by the geotechnical equipment, no other specifications for the geotechnical devices were included in the scope of this project. The Ryan Beaumont Co. has taken responsibility for the design of the suction caisson anchoring system, so the student design team engineered the full-scale submersible around the company’s plans in that regard.

Given the above design assumptions and constraints, the original design parameters for the full-scale Triton device that needed to be met by the student design team include:

Be towable by a one-ton hydraulic winch behind a chartered vessel

Counteract forces and moments caused by the geotechnical equipment

Comply with trailer size restrictions of 48 feet in length and 8.5 feet in width

Have the ballast system control the ascent and descent of the vessel

Control with umbilical lines running from the chartered vessel to the Triton

1.3 Scope of Prototype Design

The prototype fabricated in the spring semester is a scaled-down and simplified model of the full-scale design. The scale was chosen to be one tenth of the original size to allow the prototype of the device to fit transversely in Crosby Laboratory’s wave tank. Simplifications to the prototype took place in various aesthetic alterations and material changes. For example, the truss frame has a reduced number of members to make the construction of the device easier and to minimize redundancy in strength. Also, the material of the ballast tanks has been changed from steel to aluminum to achieve similar weight to buoyancy ratios for the prototype and full-scale model.

Components of the prototype were configured and sized by the design team, although much of the equipment necessitated by the design, such as air pumps for ballast tanks, are to be purchased. All fabrication of the prototype took place in the Crosby Laboratory under the supervision of graduate students and professors. The prototype was subjected to stability testing in the wave tank in Crosby Laboratory and to submersion testing in the Wallace Pool at the Memorial Gym. A comprehensive laboratory report was composed for the stability testing process. This report discusses the final full-scale design, the final scaled prototype, the development process for both, and an assessment of how well the scaled prototype worked.

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2.2 Ballast Tanks

The ballast tanks were cut from aluminum tubing to specified lengths using a horizontal band saw. Circles, the diameter of the tubing, were cut from a flat aluminum sheet to serve as end caps, and were TIG welded on. Next, air inlet and water inlet holes were drilled in the tops and bottoms of the tanks, respectively, using a drill press.

2.3 Air System

At the surface, the ballasting and de-ballasting of the device is controlled by compressed air. The air is supplied by a tank filled to approximately 100psi. A line regulator is then connected to prevent exceeding the working pressure of the hoses, valves, and fittings. The regulator also allows for control of the pressure of the air in ballasting. After the regulator there is a T-valve that permits either venting to the atmosphere or using the compressed air in the tank. After the T-valve comes a 4 way manifold with breaks the air supply into the 4 necessary lines for each ballast compartment. Each supply line has its own solenoid which controls air flow to each of the compartments in the ballast tanks. The lines then travel down the umbilical, each to its specific compartment. Figure 2 shows these components.

Figure 2: Air supply system arrangement

2.4 Control System

The control system was developed to monitor the ballasting and de-ballasting of the device. Using an Arduino microcontroller, a six degree-of-freedom inertial measurement unit (IMU) board, LabVIEW software, power supplies, relays, and a breadboard, the system is

P a g e | 5

capable of autonomous operation. The system works by using case structures in LabVIEW that activate or de-activate relays to open or close solenoid valves depending on the angular displacement of the device. The microcontroller and IMU board are located in a dry box mounted on the submersible device that has been custom fabricated so that wires may run to a laptop computer on the surface. The IMU is responsible for providing the angular displacement input necessary for the control system.

Figure 3: The controls dry box and breadboard-relay wiring setup

3 Design Concept Process

3.1 Overview

The Triton vessel was designed to meet requirements made by R.M. Beaumont Corporation (RBC). In the project proposal, the main objectives of the Triton vessel were to safely carry geotechnical equipment to the seafloor, to provide a stable platform for geotechnical tests performed, and to have the vessel return to the surface. Specific towing weight and size limits were also set. RBC requested that our vessel accommodate drilling, rock coring, and soil sampling procedures. The current procedures for these tests are slow, expensive, and are surface based. To speed up a typically month long procedure, the Triton was to be designed to perform its mission in 24 hours. By designing the vessel to satisfy the design and time requirements, the expenses would be greatly lower than the current surface based method.

Although the team would create a design package for a full-scale Triton platform, building the full-scale device was outside the scope of the project. Instead, the team undertook to build a scaled down working prototype as a proof of concept exercise. In the following sections, we first describe the full scale design we had finished by the end of the fall 2013 semester, and then we describe the scaled prototype we designed and constructed during the spring 2014 semester to perform certain proof of concept tests.

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As for accommodating the exploration equipment, the cone penetrometer and the rock coring drill were placed in the middle of the front and back sections of the frame in order to keep the reactions symmetrical.

3.2.1.1 Material Selection for Full-Scale

The building material we chose to use for the frame is Type 316 Stainless Steel, chosen mainly because of its corrosion resistance. It is also relatively cheap compared to other stainless steel alloys, and has superior ability to be welded.

3.2.1.2 Full-Scale Pontoon Arm Design

Since the width of the vessel was restricted by road regulations, we decided to design foldable arms to allow the pontoons to be raised and lowered, narrowing the footprint and allowing the device to be transported more easily. The geometry of the arms was designed so that the arms would retract into the frame when the vessel is on land. When in water, the arms deploy lowering the pontoons below the frame and turning the device into a catamaran type vessel.

To achieve these design criteria, CAD software was employed to design the geometry of the arm mechanism. Ultimately, a four-bar linkage with an added linear actuator was chosen. The three links were 1.5m long, to be made with the same material as the frame. The actuator was 1.7m long fully retracted, with a stroke of 0.66m. The hinges were unique and would have to be custom machined.

3.2.2 Ballast Design

The ballast tanks take on two major functions in relation to the mobility of the structure:

First, the tanks need to perform as pontoons to keep the vessel afloat while it is being towed out to the geotechnical location of interest. To do this, the pontoons were designed to be completely empty during towing to provide as much buoyant force as possible to elevate the frame and equipment out of the water. This will minimize the overall drag created by the vessel and will allow it to be towed much easier. The remaining factor creating drag in the water is the pontoons themselves. To accommodate this, the pontoons were designed as hydrodynamic as possible. The final design locates the ballast tanks in a catamaran configuration with one tank on each side of the structure.

The second function of the ballast tanks is to control the buoyancy of the structure during ascent and descent. The levels of water inside of the tank were designed to be monitored at all times to maximize desired ascent and descent rates as well as controlling the stability of the structure under water. Each ballast tank is to be divided into three compartments to create bulkheads. The bulkhead water volumes would be controlled separately to increase stability and counteract any undesired motions.

P a g e | 8

To initiate descent, the ballast tanks will be filled with a desired amount of water and air will be pumped out of the tanks to regulate the pressure. This will create negative buoyancy and allow the vessel to sink to the ocean floor. To ascend, air will be injected into the tanks as water is simultaneously pumped out. The buoyancy will once again become positive and elevate the vessel to the surface.

3.2.2.1 Sizing the Full-Scale Ballast Tanks

When designing the physical properties of the full-scale ballast tanks, the main focus is to trap enough air to counteract the entire weight of the structure to keep afloat during the towing procedure. This weight includes all payloads as well as all of the hull components and any additional weight due to environmental conditions. Since the tanks will be required to hold pressure, the most practical shape for the tanks is long cylinders with rounded edges. This cylindrical shape was derived from common pressure vessel and pontoon practice. The buoyant force created by the entrapped air was calculated to be greater than the weight entirety of the vessel, this creates reserve buoyancy. Reserve buoyancy is important to accommodate any added weight and also adds to the stability of the structure. This extra buoyant force also takes into consideration damage criteria; if one tank becomes damaged and fills with water the vessel still possesses enough buoyant force to reach the surface. Also considered during the ballast tank design is the transportability. The tanks are connected to mechanical arms on the frame in order to fold upward during transportation to conform to traffic regulations. Due to this, the maximum tank diameter was limited and the ballast tanks were designed to be slightly longer than the frame to reach appropriate buoyant force.

3.2.2.2 Material Selection for Full-Scale Ballast Tanks

The material chosen for the full-scale ballast tanks is ASTM-A36 Structural Steel. This is common steel with relatively high yield and ultimate strengths. When calculating the stresses on a pressure vessel the stresses act mainly in two directions, longitudinally and along the circumference of the structure. Typically the hoop, or circumferential, stress is twice that of the longitudinal stress. In this case both stresses are well under the yield strength of the material. The remaining failure method for the tanks is buckling. This is counteracted by the bulkheads, which act as stiffeners for this loading case. The steel thickness is then determined by the pressure at the maximum operation depth of 70 meters. The tanks need to be thick enough to tolerate the pressure as well as any small impacts during the expedition, yet too thick will have large impacts on the overall weight.

3.2.3 Stability & Control System

During the fall semester, the control system design subgroup was primarily concerned with stability analyses that would be necessary to understand and develop a working control system in the spring semester. Concepts were learned from Professor Thiagarajan in MEE 489,

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3.3 Prototype Design

3.3.1 Frame

3.3.1.1 Sizing the Prototype

In the design of the prototype, we were concerned about the welded frame holding together, as well as it being strong enough to support the payload, the arms, and the pontoons. We chose to ignore the forces of the cone penetrometer and the drill, since we do not have equipment able to simulate the forces to scale, and since the full-scale model was already designed and analyzed with the forces taken into account.

Part of our capstone includes the testing of the device, so the prototype needed to be sized to easily fit in the wave tank and in the university pool. We decided to design it to a one-tenth scale in order to be able to fit the vessel transversely in the wave tank.

Another sizing criterion was the scaling of the weight. Since the weight is proportional to length cubed, scaling down the size of the device by 1/10 meant scaling the weight by 1/1000. This proved impossible with the prototype frame, whose members would not have had sufficient strength if we had used correctly scaled wall thickness. So we accepted the inevitable extra weight and compensated elsewhere.

3.3.1.2 Material Selection for Prototype

As mentioned in the Sizing section, choosing the material came down to scaling the weight, as well as choosing a material strong enough that would also be easy to weld. We started with PVC tubes, because of its availability, which would speed up the fabrication and installation. However, we quickly realized this material would be too heavy for our scale.

Later, we decided to test hypodermic stainless steel tubes. After building a model on SolidWorks, we knew the weight would scale properly. It was not until we welded a joint to test its strength that we realized the wall thickness was not high enough for welding.

We finally decided to go with stainless steel tubes with an outside diameter of 0.25 inches and an inside diameter of 0.12 inches. These tubes have a wall thickness high enough to support the welded joints. We decided to use 304 stainless-steel since it is strong, commonly used, and it has a higher corrosion resistance than other steels, which is required because the vessel will be used underwater.

3.3.1.3 Prototype Pontoon Arm Design

As discussed in the full scale design section above, we wanted to allow the pontoon arms to be raised and lowered. The mechanism was scaled down and redesigned slightly: threaded

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rods were chosen for the three links, vinyl ball joints were chosen for the hinges, and small pneumatic actuators were chosen to drive the mechanism.

3.3.2 Ballast Design

3.3.2.1 Sizing the Prototype Ballast Tanks

To size the scaled model ballast tanks, a third degree exponential scaling factor was used to determine the required volume inside the tanks. This volume would provide the correct amount of buoyant force considering all other scaled elements. For simplification reasons the original design of three bulkheads is decreased to two, in order to minimize umbilical size and ease the manufacturing process. Slight shape modifications were also made to increase accuracy of the operating volume and also for more practical fabrication. The final prototype shape of the pontoons is a cylinder with flat-disc caps on the ends.

3.3.2.2 Material Selection for Prototype Ballast Tanks

The original material selection for the scale model design was PVC piping. This would make fabrication very simple due to availability and price. PVC is commonly used in saltwater because of its resistance to corrosion. The main problem with using this material is that the ballast tank ratio of structural weight to buoyant force was dismal. The final material choice is thin-walled aluminum. This provided accurate weight and performance specifications. The aluminum proved to be lightweight, to be durable, and to have a constructible design. The required thickness was recalculated to accommodate for the appropriate scaled operation depth. As a result of availability, the dimensions for the ballast tank were increased slightly in order to be able to buy off-the-shelf aluminum tubing.

3.3.2.3 Airflow System

We needed a system to transport air to the tanks when the Triton is on the bottom of the pool. A bundle of 4 reinforced plastic tubes, one line to each tank, transports the pressurized air to the tanks when necessary. The airflow system is made up of a compressed air tank, an air pressure regulator, a T-valve, a four way manifold, and four solenoid valves which lead to the hose bundle. Air coming from the compressed tank travels through the four way manifold; which splits the single airline into four individual lines. The pressure regulator is located between the pressure tank and manifold to control the pressure in each of the four hoses. Each solenoid is responsible for directing air into one ballast tank, and the solenoids are able to be independently controlled. This enables autonomous control of the structure during ascent and descent. The airflow system is driven by the software written control system to offset the moments created by the force of the waves acting on the vessel. A schematic of the airlines system is shown below.

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Figure 6: Diagram of the airline system

3.3.2.4 Fabrication & Installation

The hoses have quick connect fittings on both ends in order to make transport and storage convenient. The ballast tanks also have aluminum tubes welded to the air inlet locations so that there was material to tap with NPT threads for the male quick connect fittings. The male QC fittings provide the locations for the umbilical lines to attach. A list of equipment specifications is shown below.

1. Tanks (dimensions present on drawings in appendix) a. Cut aluminum tube for tank walls using a horizontal band saw b. Cut circular tank end caps out of aluminum sheet with an aluminum band saw c. Tig weld caps to tubing to form closed tanks d. Drill air inlet and water inlet/exit holes in tanks using ¼” drill bit on drill press. e. Cut and tap aluminum pipe to form air inlet fitting

2. Umbilical/Air Line System a. Cut bulk length hose to appropriate length b. Used barbed fittings and hose clamps to ease assembly and increase safety c. Assemble necessary hose segments from tank to manifold and manifold to

solenoid valves d. Use spiral bundling in conjunction with zip ties to form umbilical components

into one, easy-to-maneuver system

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Airline Components

Solenoid Valve (4): 3/8” 12VDC NPT Electric, normally closed

4-Way Manifold: 3/4” in, 3/8” out

T- Valve: 3/4” in/out

Air Pressure Regulator: 0-145 psi, 3/4” in/out

Air Tank: 0-200 psi, 13 gallon capacity

Hose Bundle: 3/4"

Figure 7: Left to right from top; solenoid valves, 4-way manifold, T-valve, air pressure regulator,

compressed air tank, and hose bundle

3.3.3 Stability & Control System

3.3.3.1 Stability of the Prototype

The control system has been designed to ballast our vessel quickly and maintain its stability so that the vessel can descend to the ocean floor during a slack tide. Slack tide is the short time, usually about 15 minutes, in between the high and low tides where there is little to no waves. Of course, since a scaled prototype is being built, the distance the device must descend and the time in which it must do so are also scaled. The vessel will not have much time to reach the ocean floor, a little over two minutes when scaled appropriately, but the stability of the vessel will greatly benefit from fewer waves.

The control system was designed to stabilize the vessel if it is thrown off balance due to wave forces acting on it. This is to be done by adjusting the levels of air and water within the segmented ballast tanks by electrically actuating solenoid valves. A geometric stability analysis of the vessel using General Hydrostatics Software (GHS) led us to focus on its transverse

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ballast tanks and create righting moments to offset the angles created by the waves. To activate these solenoids requires additional equipment such as power supplies and relays.

3.3.3.2.1 Software

LabVIEW has been chosen to be the software to use for the control system. LabVIEW is capable of collecting data and integrating the different segments of the control system. Using the downloadable VI packages, we are given the LabVIEW functions that can easily take outputs from the microcontroller and convert the signals into usable data. Details of the virtual instruments created for this project are covered in depth later in the report.

3.3.3.2.2 Microcontroller

An Arduino Mega is used to drive the control system. The microcontroller is responsible for taking signals sent from the sensor and transferring it into the LabVIEW software. The microcontroller was chosen for its compatibility with most equipment and software. It is also capable of running the solenoid valves by controlling the current that will open and close the valves.

Figure 9: The Arduino Mega microcontroller and 6-DOF IMU combo board

3.3.3.2.3 IMU Digital Combo Board

The inertial measurement unit (IMU) combo board is made up of an ADXL345 accelerometer and an ITG3200 gyro. Implementing the IMU board with the microcontroller, the roll, pitch, and yaw angles of the device can be determined. The calculated angles are used to demonstrate the angles of the vessel during wave testing, and act to legitimize our stability calculations experimentally.

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3.3.3.2.4 Power Supply

The power supply is an Elenco Precision Quad Power X-581, which produces up to 20 volts DC, and is used to electrically actuate the solenoid valves. One power supply is capable of powering two solenoid valves, and therefore two power supplies are required.

Figure 10: The Elenco 20VDC power supply and Kyotto DC solid state relay

3.3.3.2.5 Relay

The relays are manufactured by Kytech Electronics, and are 32 volt input and 4 amp, 60 volt output. One relay is required for each solenoid, and therefore four of them are necessary. The relays act as the midway point between the stored power supply and each solenoid valve, and control whether each valve is either open or closed. The relays are ultimately controlled by the Arduino microcontroller board.

3.3.3.3 Programming

The original goal of the control & stability subgroup was to develop a system that was capable of autonomous stabilization when the device experienced excessive angular displacement. Using an IMU board, a microcontroller, solenoid valves, relays, and LabVIEW software, such a system has been created. One concern that we had with this system is that it might potentially create more stability issues than it solves if valves are rapidly activating and deactivating in wave cycles. Therefore, a more rudimentary system was also built that allows a user at the surface to actuate each valve manually in the event that our concerns were realized.

LabVIEW is a graphical programming platform that allows the user to essentially write a computer programming code using virtual blocks that represent commands. It was ideal for our application because it is nearly unparalleled data acquisition software, it is compatible with Arduino microcontrollers, and it is software that we’ve all had brief experience with from Mechanical Laboratory courses.

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3.3.3.3.1 Autonomous Control

A VI was created that essentially takes the data readings given off by the IMU board through the microcontroller, and then determines whether or not to signal the microcontroller to activate a relay based off the readings. The decision is made depending on if the readings represent a displacement greater than an arbitrary maximum heel angle in roll or pitch. Four relays act as buffers between the power supply and the four solenoid valves. When activated, they allow current to pass through them and on to the solenoid valves, which is how each valve is opened. Once the microcontroller no longer activates the relay, current flow is discontinued and the valve closes.

The first “Arduino Init” VI block is used to communicate with and control the microcontroller by specifying the COM port, the Baud Rate, the Board Type, and the Connection type. The “Init I2C” block allows the microcontroller to communicate to the IMU board and collect its output data. The “I2C Write” blocks are allowing the microcontroller to control the sensors on the IMU board, telling it when to start collecting data, and when to turn on and off. The “I2C Read” block reads the information coming from the sensor, and the IMU board sends out a voltage that can be converted into a corresponding angular displacement. The maximum voltage output (256 mV) is sent from the IMU board when the sensor reads a 90 degree displacement. Using this knowledge, we were able to divide the voltage by 256/90 (2.844) and receive angular displacements ranging from 0 to 90.

Figure 11: The LabVIEW virtual instrument created for autonomous stability control

The data being collected is used as true-false criteria for case structure loops used to activate the solid state relays. The case structure loop changes the VI based on the true-false input. Inside the loop, the “Arduino Set Digital Pin” and “Arduino Write Digital Pin” reference the location on the microcontroller where a signal will be sent to depending on the true false

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status. If the loop is true, the microcontroller will send a “0” to the digital pin and the relay will close the switch and open the solenoid valve. If the loop is false, the microcontroller will send a “1” to the digital pin and the relay will open the switch and create a short in the circuit, closing the solenoid.

3.3.3.4 Installation

3.3.3.4.1 Autonomous Control Wiring

The control system features a myriad of wiring connections that are necessary to both record angular displacement data and activate solenoid valves. The wiring process requires the purchase of many other equipment items such as 16 gauge copper wire, breadboards, and terminal blocks. To ensure reliable wiring, wires must be firmly in position at each and every connection. In some cases wire must be soldered directly to an object, and in other cases wires must be connected to a breadboard using a terminal block which acts as a junction between the two. The breadboard is a vital tool in the wiring scenario because it allows us to integrate a large number of connections while also making the system more visually appealing. Pins on the breadboard are interconnected in segments, so that a number of wires may meet within a segment to connect them without the need for a soldered union.

Figure 12: A schematic of the autonomous control system wiring

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First, the IMU is wired to the microcontroller board at the matching connection point labels on each object. A USB attached to the microcontroller is responsible for transporting information between it and the laptop computer. From the microcontroller, wires are strung out to the breadboard where they meet with two input pins from each relay. Connecting to the two output pins of each relay are a connection to the power supply and a connection to a solenoid valve. The solenoid valves also feature another wire that is connected directly to the power supply through the breadboard to complete the loop through which power travels. A diagram is shown below that has been virtually developed for reference. Please note that the actual setup features four solenoid valves and two power supplies, only two valves and one supply have been shown in the figure for clarity.

3.3.3.4.2 Switchboard Wiring

The wiring for the alternative switchboard control system is nearly identical to that of the autonomous control system. The only difference lies on the breadboard where the relays were featured in the latter. Instead of relays, toggle switches are connected to the breadboard. Since the relays were essentially acting as automated toggle switches in the case of the autonomous control, it is clear that by placing actual switches at these locations we will be able to actuate the solenoid valves manually. Refer to the wiring schematic for the switchboard scenario pictured below. Please note that the actual setup features four switches and solenoid valves, only two of each have been shown in the figure for clarity.

Figure 13: A schematic of the manual switchboard control wiring

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3.3.3.4.3 Switchboard Control Box

A switchboard control box has been fabricated using fiberglass that features four control switches on the top face and a hollow interior that houses the breadboard, and in the case of autonomous control, relays. While running manual ballast control, each switch corresponds to a solenoid valve which is actuated at the flip of a switch. The top face is attached to one side of the box using hinges so that the face may be opened and closed to facilitate wiring changes. The purpose of the box was to not only create a manual interface for ballast control, but to also isolate the abundance of wires and connections into a transparent, enclosed region.

Figure 14: Fiberglass manual switchboard control box

3.3.3.4.4 Solenoid Valve Mount

To keep the solenoid valves in an upright and stable position, a mounting surface was built using a wooden 2x4. A long horizontal piece was butted between two vertical pieces with screws to keep the mount from simply resting flat on a surface. Two long screws were threaded through the base plate of each valve and into the horizontal piece of wood. Not only does the wooden mount keep the valves steady, but also organizes a crucial section of the airflow system. The mount is visible in Figure 7.

3.3.3.4.5 Dry Box

The first step in the installation process was to create a dry box for the IMU board so that it may be on board the device to record angular displacements. In addition, the Arduino microcontroller had to also fit into this same dry box because long I2C connections (i.e. the IMU to the Arduino) can generate significant noise in data readings.

We went about this issue by purchasing a Pursuit 40 dry box from Otterbox, and drilling a hole on the top surface so that wires may run to the computer interface and solenoid valves on the surface. Once the necessary hole-size was determined and the wires were fed through, the hole was enclosed using a marine sealant. We ran into leakage issues with the marine sealant alone, and therefore the next step was to seal the box entirely using silicone adhesive. Although this was unfavorable because it permanently restricted access to the box’s contents, it was necessary to prevent water damage to the electronics. Aside from using a compound latch to seal,

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the Otterbox features interior padding to prevent impact damage to the objects and a web hammock that limits movement of the objects within it. The dry box is shown in Figure 3.

3.3.3.5 IMU Calibration

To obtain accurate angle readings, the IMU board needed to be calibrated. The IMU board readings, without calibrating the signal, start off with a small error and slowly grow larger as the angle gets larger. To find the calibration curve, the correct angles were compared to the IMU angle reading for known angles ranging from 0 to 90 by increments of five. A protractor was used to accurately read the angle the IMU board was supposed to be reading. Each angle was held for ten seconds and averaged to accurately obtain the angle readings from the IMU. The IMU readings were graphed against the known angles, and a best fit trend line was created. Using the trend line equation from Excel, we used the equation to manipulate the signal in the LabVIEW VI to get more accurate readings from the IMU board. The calibration curves are shown in the figures below.

Figure 15: Calibration curves for the inertial measurement unit

4 Final Design Testing & Evaluation

The Triton design team has conducted a number of experiments to validate the degree to which the finished prototype meets the design objectives determined at the outset of the project. An overview of each experiment, consisting of objectives, experimental setup, and results, is included in the proceeding subheadings below. One of these experiments, stability testing in the wave tank, was highlighted in a comprehensive laboratory report as a requirement for MEE 443. This report may be observed in full in the Appendix.

4.1 Stability Testing

4.1.1 Introduction & Objectives

Stability testing was used as the experiment to satisfy the requirements of MEE 443, and because of this was the most rigidly structured experiment conducted by the design team. The wave tank in Crosby Laboratory was used to generate waves for this experiment. The primary purpose was to observe the response of the device when subjected to scaled levels of extreme

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environmental factors set for the full-scale design from the first semester. The objectives of the stability testing are as follows:

Use the Crosby Laboratory wave tank to simulate environmental forces on the submersible device

Introduce at least 5 different levels of wave magnitude to the device in two different situations; when the device is floating and when it is fully submerged at the bottom of the tank

Obtain data for the angular displacement (heel angle) of the device as a function of time using a 6 degree of freedom accelerometer/gyro IMU Combo Board

Compare heel angle results to plots of wave amplitude generated by the wave tank

Determine the highest magnitude of wave strength that the device may withstand for each situation (amplitude and test position) based on a maximum heel angle requirement

Plot wave amplitude and angular displacement vs. time for all 5 amplitudes and each test position

4.1.2 Experimental Setup

To conduct the stability test, the most important pieces of equipment are the wave tank and the IMU board. The wave tank is responsible for simulating the conditions at which stability is desired, and the IMU board is the means by which transient angular displacement data is measured. The IMU is integrated with the Arduino microcontroller board and LabVIEW software so that these measurements may be logged and recorded. For underwater wave testing, the ballast air-line system becomes necessary to flood the tanks and allow the device to submerge. See the figure below for a schematic of the experimental setup, and Figure 6 for a blow up of the air-line manifold. For complete equipment specifications refer to the Lab Report in the Appendix.

Figure 16: Schematic of the wave tank experimental apparatus

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Equipment / Instrumentation List:

1. Wave Tank 2. Triton Submersible Device 3. IMU Digital Combo Board 4. Microcontroller Board 5. Laptop Computer (2 required) 6. Air Tank 7. Air Pressure Regulator 8. Pneumatic Manifold 9. USB cable (30 feet) / 16 Gauge Wire (200 feet) 10. Rope Tether 11. Relay (4 required) / Breadboard 12. Power Supply (2 required)

4.1.3 Results

The stability of the device during wave testing was impressive in the transverse direction. Longitudinal stability was also tested to confirm our hypothesis that the transverse direction was the limiting factor, but no data was taken. Several different combinations of wave periods and amplitudes were subjected to the device, often times failing to disorient the device more than 10-15 degrees.

Unfortunately, all angular displacement measurements obtained come from an inclinometer attached to the frame of the device. The IMU board that was intended to collect transient angular displacement data failed to collect any meaningful information. The waves within the tank created vibrations that ended up inducing erratic data that did not adequately describe the behavior of the device. Although this was catastrophic to the development of useful graphs and models, with the use of the inclinometer we were able to at least quantify an approximation of the maximum displacements that the device experienced in each situation. Refer to the lab report included in the appendix of this document for more specific results and thorough summarization.

4.2 Submersion Testing


Submersion testing was the other integral experimental procedure that was conducted by the design team. For this experiment the Wallace Pool in the Memorial Gym was used. The full-scale design required that the device make its 70 meter descent and ascent in less than 15 minutes each, allowing it to complete the travel safely within a slack tide. The depth of the pool is 13 feet, which leads to a scaled descent time of just over two and a half minutes. Remaining stable while submerging to the bottom of the ocean and while returning to the surface is crucial

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to the performance of the full-scale design; this is due to the geotechnical equipment that is to be on board the device that must be protected. To ensure stability, the autonomous control system is utilized. The goals of the submersion testing are as follows:

Use the Wallace Pool to simulate ocean descent and ascent for the prototype

Complete the 13 foot ascent and descent of the device within the scaled slack tide timeframe of 160.5 seconds

Remain stable utilizing both the autonomous ballast control system and manual control


The setup for submersion testing in the Wallace Pool is nearly identical to that of stability testing in the Crosby Laboratory wave tank. One difference between the two is the test medium, where the pool is now being used as opposed to the wave tank. Other differences are that only one laptop computer is required since there is no longer a wave generation interface, and that no tether is used because the device is held in position using a makeshift pulley system. The pulley system consists of a long aluminum rod that rests on top of two diving boards located on the edge of the pool, and a cardboard spool covered with duct tape that is threaded through the rod. The umbilical is fed over the spool, and effectively limits the tension forces acting on the device to act in the vertical direction. This is an effort to reduce the possibility of having two of the four ballast tanks ballast or de-ballast quicker than the rest due to an inclination of the device from tension acting horizontally in the umbilical. The results are smoother descent and ascent trials. Refer to the equipment list in the previous section for the numbers in the pool experiment schematic.

Figure 17: The device during testing in the Wallace Pool, and the experimental setup

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4.2.3 Results

For the manual ballast control system, submersion testing was a large success. The inherent instability of the device while underwater attempted to de-stabilize the device, but by manually filling and adjusting each bulkhead with water with the use of switches it was possible to reach the bottom of the pool and return to the surface without flipping. At least five separate tests were run in which the device maintained stability, with descent times ranging from 26.8 to 116 seconds and ascent times ranging from 33.5 to 78 seconds. The large variation in times is due to the nature of the system being manually controlled. As the user become more comfortable controlling the device it was possible to speed up the process.

For the autonomous ballast control system, submersion testing began very promising but ultimately ended up being a disappointment. The very first test that was run using the LabVIEW designed system, the device made it to the bottom of the pool successfully in approximately 35 seconds. Shortly afterward, the dry box that was custom fabricated to house the IMU board and Arduino microcontroller began to leak and allowed water into the box. The result was a damaged IMU board that unfortunately made it impossible to continue assessing the potential of the autonomous ballast control system. From that point forward, the manual switchboard system was used to continue with testing.

4.3 Draft and Steady-State Keel Evaluation


The most basic form of testing conducted by the design team was the evaluation of the submersible device’s draft and steady state keel. Draft is defined as the vertical distance from the keel of an object (the bottom most point) and the waterline when an object is resting on the water’s surface. A theoretical value of the draft has been calculated based on the weight and geometry of the device. Steady-state keel is the inclination with which an object rests when floating on the water’s surface. These parameters are crucial to the performance of any offshore object because they have implications in the object’s stability. The objectives of these two brief experiments are as follows:

Obtain the experimental draft by marking the waterline on the ballast tanks and measuring the distance with a ruler

Compare the theoretical and experimental values of the draft, then alter any calculation using draft accordingly

Determine an approximate steady-state keel of the device by observing the angular displacement outputs from the IMU board while resting on a calm water surface

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Quantify the response when a heave impulse is applied to the top of the submersible device

Quantify the response when a roll impulse is applied to the center of the ballast tanks


Much like the draft and steady-state keel testing, heave and roll displacement testing is basic and may be done by placing the device in either the wave tank or the pool. Also like the other tests, this may be conducted with the experimental setups of either stability or submersion testing but does not need all of the capabilities of those setups. The design team chose to execute heave and roll displacement tests in the wave tank. Refer to Figure 19 for a representation of where the impulses might be applied for testing.

Figure 19: Impulse application points for heave and roll displacement

4.4.3 Results

Heave and roll displacement tests turned out to be quite successful. To quantify heave displacement, we forced the device to be fully underwater by applying force to the top center of the frame with. Its response was a violent return to the water surface with most movement occurring in the Z-orientation. In roll displacement, the device was forced at just short of the angle of vanishing stability as determined by the GHS model (40.65 degrees). The device responded by flipping back into an upright position while oscillating in roll briefly until settling down back in equilibrium. Our intention was to record the response of the roll displacement using the IMU board, but similar to our issues in wave testing the data contained a significant amount of vibration and therefore the data was not usable.

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5 Conclusions

The prototype model based on the original, full-scale design has given us insight on how a submersible device such as Triton may operate in real world applications. The design team set out to validate the performance of the prototype by setting various design and testing requirements based on the desired capabilities of the full-scale design.

The primary goal of the prototype was to remain stable during all phases of deployment, including underwater and above-water situations. The model proved very stable when subjected to several different wave amplitudes and wave periods, responding quite well and not showing signs of instability that would lead to capsizing. The design of the prototype resulted in an inherently unstable object underwater due to the center of gravity being higher than the center of buoyancy. In addition, uneven descent and ascent led to the sloshing of water in the ballast tanks. Despite these issues, the device was effectively submerged and returned to the surface well within the target time restrictions using manual ballast control. Although the device did not remain flat during the entire test, adjustments were made quickly enough to prevent exceeding a dangerous level of heel. We were also able to submerge the device on one trial run utilizing the autonomous control system prior to sustaining water damage.

Another goal for the design of the prototype was to achieve a high level of structural integrity, which was met by welding the small, segmented members of the frame together. The fabrication process left us with a very rigid and strong frame prototype. Constructed using steel tubing, the frame can withstand great force without deformation or failure.

The prototype featured a pontoon arm mechanism that allows the position of the tanks to be adjusted. The full-scale design called for retractable arms so that the width of the device does not exceed state of Maine road regulations for the width of an object being towed by trailer. Designed with pneumatic actuators, the mechanism keeps the arms in a horizontal position when pressurized and in a more vertical position when decompressed.

Yet another goal for the Triton prototype was to conceive a control system that is capable of collecting angular displacement data and using it to actuate solenoid valves that control the flow of water into the ballast tanks. The IMU board, the equipment that collects angular displacement, was to serve a dual purpose in that it could collect data for a laboratory experiment in which transient angular displacement would be compared to the behavior of waves generated in the wave tank. Two main problems arose with this system: the accelerometer was ineffective in wave tank testing due to vibrations induced by the waves, and the dry box on board the design was not designed robustly enough to keep out water for extended periods of time under the water pressure at the bottom of the pool. Although the accelerometer successfully collected data when rotated by hand, the data from wave testing proved completely unreliable and oscillated every few milliseconds. As mentioned earlier, the autonomous control system was also successful prior to sustaining so much water that the IMU board was damaged beyond repair.

P a g e | 29

The design process for the Triton comprised a full-scale design and a prototype scale model. Both the full-scale model and prototype design were thoroughly developed with the use of drawings and calculations. However, a great deal of time was spent on the fabrication of the prototype model. As with many engineering projects, unanticipated problems arose frequently that required rapid solutions so that the fabrication process could continue on pace. Regrettably, we feel that the overall deliverables associated with this project could have been improved slightly if the fabrication stage had been undertaken earlier in the spring semester. Issues such as inadequate data collection, insufficient waterproofing, and troubleshooting the arm design could have been overcome if they did not occur with such little time to go in the year. We felt that the corrections and alterations that we made in order to reach the final product were as optimal as possible in rectifying the problems that we encountered, given the amount of time left to solve them.

6 Recommendations for Future Designs

Over the course of the year, we have identified a number of elements that could use further improvement in design to enhance the overall effectiveness of the original Triton prototype. In addition, we have developed some potential design innovations that future project groups could take into consideration for a new and improved prototype.

6.1 Improvements in Design

6.1.1 Pneumatic Arms

The main concern with our pneumatic arms was that the actuators were not capable of supplying the required force to actually actuate the pontoons. At their max operating force of 22lbs. at 100psi the tanks would only raise an inch. Deploying the arms was not difficult, but raising the required the assistance of an operator. Therefore, more robust actuators that are capable of supplying a greater force at a much lower pressure are desired. The arm mechanism itself lends to this issue as well, the nature of the frame as a result of welding created a difficult situation. Because the frame was irregular making the arms equal and level was very difficult. Nylon ball joints were used for all the connections. This accounted for the play and offset, but also allowed for extra movement of the tanks, and potential moment generation that the actuators could not counteract.

The arm mechanism’s only flaw was that it took up space on the frame where the payloads would be placed, and the arms on the opposite tank had to be oriented so that there was no collision between the two. This forced the mounting points on the ballast tanks to not be symmetrical. Our recommendation would be to design a simpler system that potentially functions simultaneously in order to optimize space and streamline operational controls. Some thought was put towards horizontally actuating arms, but that is difficult geometry to work out with the frame cross members present.

P a g e | 30

6.1.2 Ballast Tanks

While we were quite happy with the choice of material and the overall performance of the ballast tanks, one thing that could be improved on is the amount of sloshing present in the current design. While it was taken into consideration in our prototype, we ultimately decided to go with only two bulkheads per ballast tank to simplify the fabrication process. We recruited the help of Matt Cameron, a welder with years of experience, to perform the job of welding the tank caps onto the aluminum tubes since it proved to be quite difficult.

The current design features bulkheads that are approximately 0.4 meters long a piece. A more ideal design would feature either more bulkheads or an even smaller scale size to reduce the overall size of the ballast tanks. Featuring more bulkheads, or reducing the overall length of the ballast tanks, would reduce sloshing and greatly improve the stability of the device. To understand how this would positively affect the design, consider a rectangular Tupperware container and a water bottle. Imagine both are half-full of water, and then that they are shaken back and forth. The water bottle experiences a much lesser degree of sloshing because there is less area for the water to move in the container horizontally.

6.1.3 Dry Box

One of the most consistent sources of issues on our project was the integrity of the controls dry box. On two separate preliminary descent tests, a considerable amount of water penetrated the box and marine sealant. To protect the electronics we decided to seal the box entirely using a silicone adhesive. Clearly this is a major drawback because the box may no longer be opened to adjust the electronics inside. The next step in the design of a dry box is to develop it such that it remains dry but also maintains accessibility to the contents of the box.

6.2 Design Innovations

6.2.1 Thrusters

The need for thrusters was expressed to us in a design review with RBC to potentially avoid rotation of the Triton during decent. Rotation could cause unnecessary twist on the umbilical and its connection points. During testing we found that if care was taken to ensure the umbilical did not have any twist in it that the Triton would not rotate during decent and ascent in idealized slack tide conditions, and only marginally in wave testing scenarios.

6.2.2 Liquid Level Sensors

One potential addition that could be made to the Triton project is by adding liquid level sensors, or having other means of determining how much water is in the ballast tanks at any given time. This could be beneficial to the design because it would then become possible to determine precisely when the device reaches neutral buoyancy. Having this information would

P a g e | 31

allow the design team to stop allowing water into the tanks once there is already enough to begin descent.

6.2.3 On-Board Optics The need for on-board optics was apparent when we found out that the Wallace Pool has a

slanted bottom surface at the deep end of the pool. Being able to see which tanks are oriented on the slope could allow for a more controlled ascent start by ballasting the lower tanks first in order to reach equilibrium. Optics would also be useful in controlling the landing. As the floor approaches, the operators could blast a small amount of air into the tanks to slow decent to a smooth gradual landing.

7 List of References

[1] R. M. Beaumont, “Triton: For Seabed Geotechnical Investigation,” R. M. Beaumont Corp., Brunswick, ME, Prop. DE-FOA-0000715, July 3, 2012.

8 Appendices

I

Triton Offshore Device: Formal Lab Report

Measuring stability of the device in mechanically induced waves

Crosby Laboratory University of Maine Orono, ME 04469

May 7, 2014

Report Composed By:

Thomas Allain Paul Amsden Ethan Gray

Brady Jacques

Erik Medina Matthew Storgaard Matthew Waldroup

II

Table of Contents:

Introduction: .................................................................................................................................................. 1

Objectives: .................................................................................................................................................... 2

Apparatus, Equipment, & Instrumentation: .................................................................................................. 3

Equipment / Instrumentation List: ............................................................................................................ 4

Theory: .......................................................................................................................................................... 5

Procedure: ..................................................................................................................................................... 7

Overview of LabVIEW VI Development: ................................................................................................ 8

Results ........................................................................................................................................................... 8

Conclusions ................................................................................................................................................. 10

References ................................................................................................................................................... 11

Appendix ..................................................................................................................................................... 11

1

Introduction:

The goal of the Triton project is to construct a submersible vessel that supports geotechnical devices intended to perform testing on the ocean floor. The vessel will be able to maintain stability while being towed on the water's surface to various locations, and also while the device is deployed to the ocean floor. The testing equipment on board the vessel that will perform the geotechnical investigation will exert reactive forces that the vessel needs to be able to handle. The current method of performing these geotechnical tests is very costly and can take up to a week to perform. The goal of the Triton project is to perform the same tests at a much lower cost and within 24 hours.

Aside from maintaining structural integrity, the most important result of the Triton project is that the device remains stable and upright during all phases of deployment. Ensuring that the device will not become severely disoriented at various current magnitudes is the most effective way of illustrating this desired experimental outcome. In order to accomplish this, the design team will utilize the capabilities of the wave tank located in the Crosby Laboratory. The aim is to subject the vessel to a range of wave frequencies and heights, and to then plot the data obtained from an accelerometer that will be located onboard. The accelerometer, while very useful in analyzing the motion of an object, will be used in this instance as a means of obtaining the angles at which the device becomes tilted when subjected to the waves.

In an ideal experiment, the design team would like to have an uncertainty in the results that is less than 5 percent. This is because the stability of an object in a fluid is very sensitive, and therefore conclusions as to whether the device will be stable at various wave amplitudes may not safely be drawn unless there is a very high level of certainty in the results. In order for this goal of uncertainty in results to be achieved, the uncertainty of the measured data will also need to be very low.

The variables to be tested in the proposed experiment are heel angle, wave amplitude, wave frequency, and time. Heel angle and wave amplitude will be plotted as dependent variables on the ordinate axis, while time is treated as the independent variable on the abscissa. Placing heel angle and wave amplitude on the same graph with multiple ordinates could be useful in creating a visual demonstration of the device’s orientation at various points in the wave sequence. An acceptable heel angle is formulated based on requirements for the device; this heel angle will act as an upward limit for the magnitude of disorientation that the device may experience. The range of wave amplitude will be determined based on environmental conditions on the three locations of interest that the original design was engineered for. A significant wave height was found last semester for the locations to be approximately 1.159 meters. However, a scale model is being constructed and therefore the maximum wave amplitudes must also be scaled. Wave heights and many other parameters do not scale linearly, so background computational work is necessary. Time intervals for the experiment are in the range of 1-2 minutes. Time intervals of this

2

magnitude provide enough data to be thorough in assessing the stability while avoiding the possibility of being redundant.

As touched upon previously, the basic nature of the experiment is to assess the stability of a scale model of the Triton device using the wave tank in Crosby Laboratory. The wave tank has an established LabVIEW interface that the design team will use to obtain transient wave amplitude data. The wave tank is approximately 1 meter wide, 1 meter tall, and 6 meters long with a water depth around 0.7 meters. A picture of the wave tank is shown in Figure 2 below.

Figure 1: Photo of the wave tank to be used for the experiment, located in Crosby Laboratory

In order to obtain the information necessary for this experiment, a number of pieces of equipment and instruments are needed. The primary pieces of equipment necessary to collect data are an IMU Digital Combo Board, a Microcontroller Board, and two Laptop Computers to process data being collected by the IMU Board and by the wave tank interface.

The vessel will be placed in the tank and subjected to several magnitudes of wave heights while floating to determine the most extreme wave condition for each circumstance that the device may encounter and remain stable enough to not exceed a maximum heel angle. The design team estimates that a minimum number of 5 different wave magnitudes will be sufficient in capturing a spectrum of how well the device will perform in a wide range of conditions. Objectives:

Use the Crosby Laboratory wave tank to simulate environmental forces on the submersible device

Introduce at least 5 different levels of wave magnitude to the device when it is floating

3

Obtain data for the heel angle of the device as a function of time using a 6 degree of freedom accelerometer/gyro IMU Combo Board

Compare heel angle results to plots of wave amplitude generated by the wave tank

Determine the highest level of angular displacement of each trial and compare that to the maximum allowable heel angle

Plot wave amplitude and heel angle vs. time for all 5 amplitudes and each test position

Apparatus, Equipment, & Instrumentation:

The experiment conducted by the design team necessitates several instruments and pieces of equipment that are used to create, obtain, and record relevant data. First, the wave tank located in Crosby Laboratory is instrumental because it is the means by which waves and currents are propagated. The wave tank is complete with an interface that provides for the collection of wave amplitude as a function of time, from which it is possible to calculate frequency and other wave parameters of interest.

To collect heel angles as a function of time, an IMU Digital Combo Board that possesses an accelerometer and gyro is mounted on the device. This combo board is capable of capturing motion in all 6 degrees of freedom, and can be paired with an Arduino microcontroller board. The microcontroller board is the means by which movement data is relayed to a laptop computer for further processing and future reference.

Because the nature of the experiment requires the device to be in water, a number of waterproofing elements are needed for the equipment exposed to the water. Refer to Figure 3 below for a visual representation of the experimental apparatus.

Figure 2: Schematic of the experimental apparatus

4

Figure 3: Diagram of the airline system

Equipment / Instrumentation List:

1. Wave Tank

Tank Size: approximately 1 meter wide, 1 meter tall, and 6 meters long

Water height: approximately 0.7 meters

Interface: Compatible with a laptop computer to obtain wave data 2. Triton Submersible Device

Pontoons Material: Aluminum T6-6061 Size: 0.8 meter long, 0.1016 meter outside diameter

Frame Material: 304 Stainless Steel Size: 1/4” O.D., 1/8” I.D., length varies by member

3. IMU Digital Combo Board

Accelerometer Model: Analog Devices ADXL345

Gyro Model: IvenSense ITG 3200

Input: 3.3 volts 4. Microcontroller Board

Model: Arduino Mega 2560 Microcontroller

Input Voltage: 7 to 12 volts

Input/Output: 54 digital I/O pins

5

5. Laptop Computer (2 required)

Model: Lenovo ThinkPad W510 or Dell PP39L

Required Software: LabVIEW and Arduino IDE 6. Air Tank

Capacity: 13 gallons

Pressure Range: 0-200 psi 7. Air Pressure Regulator

3/4” Diameter in/out

Pressure Range: 0-145 psi 8. Pneumatic Manifold

3/4” Diameter Y-Valve

4-Way Manifold 3/4” diameter in, 3/8” out

Solenoid Valve (4 required) Model: US Solid 3/8” NPT Electric, normally closed Part Number: JFSV00006

Barb Fitting (5 required)

3/4” Diameter Inlet Hose

3/8” Diameter Outlet Hose (4 required) 9. USB cable (30 feet) / 16 Gauge Wire (200 feet) 10. Rope Tether 11. Relay (4 required) / Breadboard

32V input, 4A 60V output 12. Power Supply (2 required)

Model: Elenco Precision Quad Power X-581, 20VDC

Theory:

The methods by which this experiment collects data are such that there are very few manipulations necessary in order to reduce data to results. As stated in the Introduction of this report the parameters of interest are the heel angle of the device, the wave amplitude, wave frequency, and time. The data that is to be collected directly are the wave amplitudes, wave frequencies, and time. Since these parameters are obtained in their desired forms, no reduction is required in these instances.

To convert the readings from the IMU into angular displacements a small conversion is necessary. The program developed for the device reads an output from the IMU in least significant bits (LSB), and converts it into an angular displacement. Each level of LSB corresponds to a force in g’s that is being read in each of the three principal directions. The IMU gives off a maximum of 256 LSB in each direction, which occurs at 90 degrees of rotation about any axis and also when the force is highest. When the IMU exceeds a displacement of 90

degrees, of 90/256appear asbelow.

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As for the scaling of parameters, factors to take into account are average and significant wave heights, and peak periods and frequencies. Appropriate scaling factors may be determined from the table below, which was obtained from a proceeding technical report from an ASME conference on Ocean, Offshore, and Arctic Engineering circa 2012.

Tables 1&2: Scaling factors derived for the testing of floating wind turbine models [1], scaled values of environmental parameters

Previously determined values for the environmental factors of interest are to be corrected accordingly. The scale size factor designated for the Triton device is one tenth, and therefore a value of 0.1 is to be used for the scaling variable shown in Table 1 above, lambda. A scaling factor of 0.1 is translatable to a wave that can be produced by the wave tank. However for the scaling computations of wave period and frequency, a larger scaling factor is in order. This is because the one-tenth scale does not reduce the wave period and increase the wave frequency to levels that may be accommodated by the wave tank. A scaling factor of 0.01 has been decided on for this reason.

Procedure:

1. Multiple group members lift the fully assembled Triton device and place it in the wave tank orientated with the port or starboard perpendicular to the wave direction

2. The device is then tethered via a rope to the upper wave tank frame. The USB chord for the onboard measuring units is to be connected, along with the tether and ballast tank air-lines

3. Once the on-board data recording equipment has been become operational, a brief test of its response is done by simply pushing downward on any portion of the Triton

4. The LabVIEW VI outlined later in this section is launched to collect experimental data

Parameter Value Avg. Wave Height (0.1) 0.073m Sig. Wave Height (0.1) 0.116m

Peak Period (0.01) 1.07s Peak Frequency (0.01) 0.0093Hz

8

5. The wave generator is then operated, executing the specified wave levels for the surface tests. This is repeated at least 5 times, making sure to store each test labeled correctly via the LabVIEW software

Overview of LabVIEW VI Development:

To get started, it was necessary to download the Arduino VI Package for Arduino adaptable functions. Using the added Arduino functions, LabVIEW can be used to communicate with the Arduino microcontroller. Refer to the Appendix for all specific block references.

The first “Arduino Init” VI block is used to communicate with and control the microcontroller by specifying the COM port, the Baud Rate, the Board Type, and the Connection type. The “Init I2C” block allows the microcontroller to communicate to the IMU board and collect its output data. The “I2C Write” blocks are allowing the microcontroller to control the sensors on the IMU board, telling it when to start collecting data, and when to turn on and off. The “I2C Read” block reads the information coming from the sensor, and the IMU board sends out a voltage that can be converted into a corresponding angular displacement. The maximum voltage output (256 mV) is sent from the IMU board when the sensor reads a 90 degree displacement. Using this knowledge, we were able to divide the voltage by 256/90 (2.844) and receive angular displacements ranging from 0 to 90. The data being collected is used as true-false criteria for case structure loops used to activate the solid state relays. The case structure loop changes the VI based on the true-false input. Inside the loop, the “Arduino Set Digital Pin” and “Arduino Write Digital Pin” reference the location on the microcontroller where a signal will be sent to depending on the true false status. If the loop is true, the microcontroller will send a “0” to the digital pin and the relay will close the switch and open the solenoid valve. If the loop is false, the microcontroller will send a “1” to the digital pin and the relay will open the switch and create a short in the circuit, closing the solenoid.

Results

The data collected during experimentation by the IMU board failed to live up to the task set out for it in collecting reliable transient angular displacement. During experimentation, it was apparent that the waves introduced to the device were inducing detrimental vibrations that caused the IMU to relay data that represented a rapid oscillation with periods on the order of milliseconds. Several different trials of experiment were run, each producing results that were misrepresentative of the actual behavior of the device.

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generated that are within a specific range of wave height to period ratio, and the ratio of peak frequency and maximum amplitude fall outside this range. However, they were able to be demonstrated separately. The approximate maximum angular displacements caused by 5 different waves are shown in Table 2 below.

Table 2: Experimental wave parameters and approximate induced angular displacement Wave Period (s) H/L Ratio Wave Amplitude (m) Approx. Heel Angle (°)

1.1 0.03 0.029491 3° 1.1 0.06 0.058982 10° 0.85 0.06 0.037949 5°

2 0.05 0.11292 2° 0.6 0.05 0.020456 15°

Conclusions

Although transient angular displacement data was not obtained in this experiment, it was still successful in determining that the Triton device will remain upright when subjected to scaled environmental conditions in the transverse direction. In fact, the trial which caused the largest displacement was only able to disorient the device by about 15 degrees. The maximum allowable angle that it can experience and still possess a righting arm occurs at about 40.65 degrees, so there is plenty of flexibility when it comes to the stability of the device during extreme circumstances.

One significant conclusion to draw from wave testing is the relationship between the wave period and the width of the device. The waves that are most disruptive to the transverse stability of the device are those with periods on the same order as the end-to-end distance of the ballast tanks. This is evidenced by the last trial in Table 2, which with a wave period approximately the same as the width of the device (0.63m), features the smallest wave amplitude of all the trials but the highest level of displacement. This is important to note because in a full-scale design, it would be critical to avoid conditions in which wavelengths are not the same length as the distance perpendicular to the wave direction. It is also important to note that aside from this, the results provide no evidence to infer any other definitive relationships between wave period size and angular displacement.

Although there is little evidence to back it up, it is hypothesized that there is a positive relationship between wave amplitude and maximum angular displacement when comparing waves with identical periods. The first trial in Table 2 features an amplitude that is half that of the second trial, but they share the same period. The end result is an increase is an increase in heel that is approximately 7 degrees higher when the wave amplitude is increased.

11

References

[1] Goupee, Kimball, Martin, Viselli. “Methodology for Wind/Wave Basin Testing of Floating Offshore Wind Turbines”. OMAE 2012-83627. http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=1733156

Appendix

Appendix A

Qnty. Description Unit Price TotalFIRST ORDER

1 3/8" NPT Electric Solenoid Valve 12-VDC Air PN: JFSV00006 $29.99 $29.99 US Solid

1 Arduino Mega 2560 R3 PN: DEV-11061 $58.95 $58.95 Sparkfun

1 IMU Digital Combo Board PN: SEN-10121 $64.95 $64.95 Sparkfun

SECOND ORDER20 Nylon ball joint rod end, female PN: 1064K711 $4.91 $98.20 McMaster-Carr14 Threaded connecting rod, male PN: 6516K110 $7.91 $110.74 McMaster-Carr

2 Grooved clevis pin, 3/8" w/ ring PN: 92735A110 $5.49 $10.98 McMaster-Carr8 Coupling nuts PN: 90264A430 $0.66 $5.28 McMaster-Carr2 Grooved clevis pin, 5/8" w/ ring PN: 92735A120 $5.55 $11.10 McMaster-Carr1 Hose & Tube Clamp PN: 54155K86 $11.83 $11.83 McMaster-Carr1 nylon tee fitting (black) PN: 5463K608 $7.37 $7.37 McMaster-Carr2 Brass port plug PN: 5454K81 $4.55 $9.10 McMaster-Carr4 Pivot-mount air cylinder PN: 6498K857 $26.89 $107.56 McMaster-Carr8 Pivot bracket PN: 4952K114 $3.74 $29.92 McMaster-Carr1 3/8" ID High-Pressure PVC Tubing clear 100ft length PN: 52375K13 $87.00 $87.00 McMaster-Carr1 3/8" ID High-Pressure PVC Tubing clear 50ft length PN: 52375K13 $43.50 $43.50 McMaster-Carr1 3/4" ID High-Pressure PVC Tubing clear 10ft length PN: 52375K16 $17.80 $17.80 McMaster-Carr1 Spiral Bundling Wrap-Around Sleeving clear 50ft length PN: 7432K33 $27.36 $27.36 McMaster-Carr2 Pipe Thread Sealant Tape: commercial grade white PN: 4591K11 $1.86 $3.72 McMaster-Carr

8 hose coupling 3/8" NPTF male, 3/8" coupling size PN: 6534K72 $4.33 $34.64 McMaster-Carr

8house couplin, sleeve Lok socket, 3/8" Hose ID, 3/8" coupling PN: 6536K62 $11.09 $88.72 McMaster-Carr

1brass barbed hose fitting 3/8" hose ID x 3/8" NPTF Male Pipe, pack of 5 PN: 5346K19 $8.78 $8.78 McMaster-Carr

2brass barbed hose fitting adapter for 3/4" hose ID x 3/4" NPTF male pipe, pack of 2 PN: 5346K28 $9.29 $18.58 McMaster-Carr

1 stainless steel hex nut 3/8" pack of 25 PN: 94804A325 $5.75 $5.75 McMaster-Carr1 pressure sealing washer 3/8" pack of 5 PN: 93781A038 $11.09 $11.09 McMaster-Carr

1 stainless steel type A flat washer 3/8" pack of 10 PN: 93852A104 $3.31 $3.31 McMaster-Carr1 Air regulator 145 max pressure 3/4" PN: 8812K38 $57.02 $57.02 McMaster-Carr

1 diverting 3 port brass ball valve 3/4" PN: 4093T24 $49.70 $49.70 McMaster-Carr

1SME-Code Horizontal Pressure Tank without Top Plate, 13 Gallon Capacity, 14" Diameter x 23" Long PN: 9888K19 $257.11 $257.11 McMaster-Carr

1 RTV sealant PN: 7462A22 $9.84 $9.84 McMaster-Carr1 Brass 37° Flared Tube Fitting PN: 50675K173 $2.99 $2.99 McMaster-Carr1 Rigid-Bristle Threaded-Arbor Cup Brush, carbon steel PN: 4771A38 $17.48 $17.48 McMaster-Carr1 flexible-Bristle Shank-Mount cup brush 1-3/4" PN: 4887A1 $13.29 $13.29 McMaster-Carr1 4" grinding wheel for angle grinder, pack of 25 PN: 44165A11 $5.76 $5.76 McMaster-Carr

1 Matala 4 Way Heavy Duty Manifold, 3/4" in, 3/8" out $42.00 $42.00www.webbsonline.com

16ft Aluminum, 6061-T6 Bare Drawn Tube 3.87" ID, 4" OD, .065" Thickness $190.34 $190.34 Onlines Metals

1 24 inches by 48 inches Aluminum Bare Sheet 6061 T6 $58.04 $58.04 Onlines Metals

136" length of Welded Stainless Steel Tube 0.25" X 0.065" X 0.12" $13.43 $13.43 Onlines Metals

130" length of Hypodermic Tubing, Gauge: 6G/Reg, Part #:HTX-06R $12.42 $12.42

Component Supply Company

4 3/8" 12VDC Electric Brass Solenoid Valve PN: 2W-160-10-12V $38.95 $155.80Electric Solenoid Valves

1 3M Marine Adhesive Sealant 5200 Black 3 oz. PN: 71-05205 $9.95 $9.95 PBS Boat Store1 Automotive Primary Wire, 16 AWG, 100 ft Black PN: 5LXF3 $13.90 $13.90 Grainger1 Automotive Primary Wire, 16 AWG, 100 ft Red PN: 5ZLN3 $18.74 $18.74 Grainger2 Solder-able Breadboard PN: 12070 $4.95 $9.90 Sparkfun

20 N-Channel MOSFET PN: 10213 $0.86 $17.20 Sparkfun8 Schottky Diode PN: COM-10926 $0.15 $1.20 Sparkfun1 30 ft A to B USB Cable PN: 247174 $21.95 $21.95 Office Depot

THIRD ORDER

1Hose Coupling, Plug, Zinc-Plated, 1/4" NPTF Female, 3/8 Coupling Size PN: 6534K74 $4.09 $4.09 McMaster-Carr

1Hose Coupling, Sleeve, Zinc-Plated, 3/8" NPTF Male, 1/2 Coupling Size PN: 6536K23 $12.10 $12.10 McMaster-Carr

1Hose Coupling, Sleeve, Zinc-Plated, 3/4" NPTF Male, 1/2 Coupling Size PN: 6536K42 $13.67 $13.67 McMaster-Carr

1Hose Coupling, Plug, Zinc-Plated, 3/4" Hose ID, 1/2 Coupling Size PN: 6534K64 $4.54 $4.54 McMaster-Carr

4Hose Coupling, Plug, Zinc-Plated, 1/4" NPTF Male, 3/8 Coupling Size PN: 6534K71 $2.61 $10.44 McMaster-Carr

1Pressure - Sealing Washer for Screws & Bolts, 9/16" Screw Size, Pack of 5 PN: 93783A034 $8.17 $8.17 McMaster-Carr

1Pressure - Sealing Washer for Screws & Bolts, 1/2" Screw Size, Pack of 5 PN: 93783A033 $14.80 $14.80 McMaster-Carr

30.25" OD x 0.065" WALL x 0.12" ID t-316/316L TUBE 36" Length PN: 4229 $18.91 $56.73 Online-Metals

1 Cut Fee $18.00 $18.00 Online-Metals

FOURTH ORDER

1Worm-Drive Hose Clamp, 1/2" to 29/32" Diameter, Pack of 10 PN: 5415K32 $6.61 $6.61 McMaster-Carr

1Worm-Drive Hose Clamp, 13/16" to 1-3/4" Diameter, Pack of 10 PN: 5415K16 $6.85 $6.85 McMaster-Carr

1 Tapered Round Rubber Plug, Size 7, Pack of 5 PN: 9545K19 $5.00 $5.00 McMaster-Carr

1Multipurpose Aluminum Tube, 5/8" OD, 0.495" ID, 1' Length PN: 9056K68 $8.05 $8.05 McMaster-Carr

2 Primer, Aerosol, Filler, 12oz, Gray PN: 7929T1 $7.12 $14.24 McMaster-Carr

2 Aerosol Paint, Low Odor, 12oz, Gloss Safety Yellow PN: 75035T41 $5.32 $10.64 McMaster-Carr1 Aerosol Paint, Low Odor, 12oz, Flat Black PN: 75035T41 $5.32 $5.32 McMaster-Carr

FIFTH ORDER

4Relay Solid State 32V DC Input 4A 60V DC Output 4-Pin PN: 175222 $9.95 $39.80 Jameco Electronics

2 IMU Digital Combo Board PN: SEN-10121 $40.00 $80.00 Sparkfun

SIXTH ORDER (INFRASTRUCTURE)1 Medium Steel Nozzle Combo PN: 6300-20 $19.95 $19.95 TP Tools1 48" Cabinet Siphon Hose, Straight PN: 6500-04 $8.95 $8.95 TP Tools1 Standard 12" x 24" Cabinet Lens PN: 6101-00 $26.00 $26.00 TP Tools1 Front Hose Gronmet PN: 6112-01 $1.95 $1.95 TP Tools

1 Skat Blast Cabinet Door and Funnel Gasket PN: 6217-00 $7.95 $7.95 TP Tools

1 Weather-Resistant Vinyl Foam (3/8" thick, 3/4" width, 10' length) PN: 93675K17 $3.29 $3.29 McMaster Carr

1 Flexible Magnet Strip (5 ft) PN: 5759K28 $2.65 $2.65 McMaster Carr1 Abrasive Blasting Media - Aluminum Oxide Grit 10lbs PN: 3398K34 $30.16 $30.16 McMaster Carr

OtterBox $20.00Epoxy $10.00Threat Tap $8.00

TOTAL: $2,304.23

0.050

0.200 0.250 0.350 0.450 0.500 0.650

0.600

0.038

0.2

25

0.0

75

0.088

0.050

0.150

0.700

0.2

25

DO NOT SCALE DRAWING

framedrawingSHEET 1 OF 1

2/5/2014PA

UNLESS OTHERWISE SPECIFIED:

SCALE: 1:8 WEIGHT:

REVDWG. NO.

ASIZE

TITLE:

Triton Frame Drawing

NAME DATE

COMMENTS:

For drawing purposes, dimensions are taken from edges ("sides") of tubing. During assembly, these dimensions should be taken from the CENTERLINE of tubing.

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

FINISH

MATERIAL:0.204" OD 304 stainless steel tubing

INTERPRET GEOMETRICTOLERANCING PER:

DIMENSIONS ARE IN METERSTOLERANCES: 0.001m

APPLICATION

USED ONNEXT ASSY

PROPRIETARY AND CONFIDENTIALTHE INFORMATION CONTAINED IN THISDRAWING IS THE SOLE PROPERTY OF<INSERT COMPANY NAME HERE>. ANY REPRODUCTION IN PART OR AS A WHOLEWITHOUT THE WRITTEN PERMISSION OF<INSERT COMPANY NAME HERE> IS PROHIBITED.

5 4 3 2 1

NUMBERPART

Information in this drawing is provided for reference only.

http://www.mcmaster.com

3"Stroke Length

0.50"

0.19"

9.25"Overall Extended Length

6.25"Retracted Length

0.38"

0.157" Pin Dia.

0.25"0.38"

0.62" OD

9/16"Bore Size

#10-32 Thread

7/16"-20 Mounting Thread

#10-32 UNF Ports

7/16"-20 Mounting Thread

0.31"

6498K857Stainless Steel Double Acting

Pivot-Mount Air Cylinder© 2011 McMaster-Carr Supply Company


NUMBERPART



0.06"

0.77"

0.16"

0.33"

0.57"

1.35"

0.75" 0.50"

0.13"

0.19"

0.20"

4952K114 Pivot Bracket with Pin for Switch-Ready

Stainless Steel Air Cylinder© 2013 McMaster-Carr Supply Company


NUMBERPART



1 3/16"

6"

1 3/16"

3/16"#10-32 Thread

6516K11Zinc-Plated Steel Right-Hand

Male-Threaded Connecting Rod© 2012 McMaster-Carr Supply Company


NUMBERPART



5/8"

1 1/16"

1 3/8"

13/32"

1/4"

5/16"

7/16"3/16"25° Max.Ball Swivel

5/16"

1/2"ThreadLength

#10-32 Thread

1064K711Nylon Right-Hand Threaded

Ball Joint Rod End© 2012 McMaster-Carr Supply Company


NUMBERPART



0.335"

+0.000 -0.020

0.029" Groove Width

3/16"

0.070" 3/4"

5/8" Usable Length

0.320" -0.0015-0.0065

+0.000 -0.020

92735A120Grooved Clevis Pinwith Retaining Ring

© 2012 McMaster-Carr Supply Company


NUMBERPART



0.335"

+0.000 -0.020

0.029" Groove Width

3/16"

0.070" 1/2"3/8"

UsableLength

0.320" -0.0015-0.0065

+0.000 -0.020

92735A110Grooved Clevis Pinwith Retaining Ring

© 2012 McMaster-Carr Supply Company


1/4-20 Tapped Hole

.065 3.87

15.50

4X .25

2.58

5.17

10.33

12.92

7.75

Ballast tank

ADO NOT SCALE DRAWING

BTank_AL_hullSHEET 1 OF 1

4/3

4/3MJW

TCA


SCALE: 1:8 WEIGHT:

REVDWG. NO.

ASIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

stock

T6061-T6 AluminumFINISH

MATERIAL


DIMENSIONS ARE IN INCHESTOLERANCES:FRACTIONALANGULAR: MACH BEND TWO PLACE DECIMAL THREE PLACE DECIMAL

APPLICATION

USED ONNEXT ASSY


5 4 3 2 1

4.00

.08

Tank Cap


BTank_AL_capSHEET 1 OF 1

4/3

4/3MJW

TCA


SCALE: 1:2 WEIGHT:

REVDWG. NO.

ASIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

6061 T6 Aluminum FINISH

MATERIAL



APPLICATION

USED ONNEXT ASSY


5 4 3 2 1

male QC air line1/4"

1/4 NPT threaded pipe for QC fitting

15.66Total Length

Ballast Tank


BTank_AssembSHEET 1 OF 1

4/3

4/3MJW

TCA


SCALE: 1:8 WEIGHT:

REVDWG. NO.

ASIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

6061 T6 AluminumFINISH

MATERIAL



APPLICATION

USED ONNEXT ASSY


5 4 3 2 1

Pneumatics Diagram Dimensions are in inches

Drawn: MJW 4/15

Checked: TCA 4/15

KG, KB, & GM (Submerged Prototype):

≔KGfp 0.132 ≔KGpop 0.0515 ≔KGbo 0.0775

≔Wfp 46.066 ≔Wpop 24.821 ≔Wbo 4.448

≔Rtp KGpop ≔KGbfp =+Rtp ――⋅4 Rtp

⋅30.073 ~ Assuming ballast tanks

are half-filled with water

≔KGup =――――――――――――――++⎛⎝ ⋅KGfp Wfp⎞⎠ ⎛⎝ ⋅KGpop Wpop⎞⎠ ⎛⎝ ⋅KGbo Wbo⎞⎠

++Wfp Wpop Wbo

0.102

≔Vpop 0.0123

≔Vfp 0.0191093

≔Vbo 0.00113

≔υup +Vbo

⎛⎜⎝――Vpop

2

⎞⎟⎠

=υup 0.0073

≔Iwpup 04

≔BMup =――Iwpup

υup

0

≔KBup =⋅――1

υup

⎛⎜⎝

+⎛⎝ ⋅KGbo Vbo⎞⎠⎛⎜⎝

⋅KGbfp ――Vpop

2

⎞⎟⎠

⎞⎟⎠

0.074

≔GMup =+−KBup KGup BMup −0.028 =GMup −1.113

≔PercentHeightp =―――GMup

0.285−0.099

Created with Mathcad Express. See www.mathcad.com for more information.

KG, KB, & GM (Submerged Full-Scale):

≔KGf 1.97 ≔KGpo 0.845 ≔KGpa 2.1344 ≔KGc 0.61

≔Wf 22530.2 ≔Wpo 11070 ≔Wpa 4445.2 ≔Wc 719.768

≔KGu =―――――――――――――――――――+++⎛⎝ ⋅KGf Wf⎞⎠ ⋅2 ⎛⎝ ⋅KGpo Wpo⎞⎠ ⋅2 ⎛⎝ ⋅KGpa Wpa⎞⎠ 4 ⎛⎝ ⋅KGc Wc⎞⎠

+++Wf ⎛⎝ ⋅2 Wpo⎞⎠ ⎛⎝ ⋅2 Wpa⎞⎠ ⎛⎝ ⋅4 Wc⎞⎠1.485

≔Vpo 4.2833

≔Vpa 1.529113

≔Vc 0.062033

≔Vf 0.293

≔Rt 0.4 ≔KGbf =+Rt ――⋅4 Rt

⋅30.57

~ Assuming ballast tanks are half-filled with water

≔υu +⎛⎜⎝

⋅2 ――Vpo

2

⎞⎟⎠

⎛⎝ ⋅2 Vpa⎞⎠

=υu 7.3413

≔Iwpu 04

≔BMu =――Iwpu

υu

0

≔KBu =⋅―1

υu

⎛⎜⎝

+⎛⎜⎝

⋅⋅KGbf 2 ――Vpo

2

⎞⎟⎠

⎛⎝ ⋅⋅KGpa 2 Vpa⎞⎠⎞⎟⎠

1.222

≔GMu =+−KBu KGu BMu −0.264 =GMu −10.38

≔PercentHeight =――――――GMu

+2.25 0.61−0.092


Inside Pontoon Length Pontoon Thickness≔ρ 63.989 ――

3≔g 32.2 ―

2≔Lc =2.625 31.5 ≔T .065

Draft Depth in Pontoon≔ID 3.87 ≔OD =+ID 2 T 4 ≔t 2.1 ≔d 0

≔r =――OD

20.167 ≔r' =――

ID

20.161

≔ϕ =2⎛⎜⎝acos

⎛⎜⎝―――(( −r t))

r

⎞⎟⎠

⎞⎟⎠

3.242 ≔ϕ2 =2⎛⎜⎝acos

⎛⎜⎝―――(( −r' d))

r'

⎞⎟⎠

⎞⎟⎠

0

≔At =―――――r

2(( −ϕ sin ((ϕ))))

20.046

2≔Ad =――――――

r2

⎛⎝ −ϕ2 sin ⎛⎝ϕ2⎞⎠⎞⎠

20

2

≔VTotal =⋅2⎛⎜⎝

−⋅――((ID))

2

4Lc ⋅――

ID2

4T

⎞⎟⎠

0.4283

*Calculated with one bulkhead, 2 flat caps≔VMaterial =⋅2

⎛⎜⎝

+⋅―――――⎛⎝ −OD

2ID

2 ⎞⎠

4Lc ⋅OD

2T

⎞⎟⎠

57.1583

≔WPVC 5.619 ―

≔WPontoons =⋅VMaterial 168.56 ――3

5.576 *Aluminum Density = 168.56

≔WTotal =+⎛⎝WPontoons⎞⎠ 9.39 14.966

≔FB =⎛⎝ −⋅⋅⋅ρ 2 ⎛⎝ −At Ad⎞⎠ Lc WTotal⎞⎠ 0.626


triton offshore device - mick petersonmickpeterson.org/2013design/groups/triton/final report.pdf ·...

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