the 2012 Marine Field Projects. The report details the motivations for the Wave Glider project,

Transcription

1 TRANSMITTAL Florida Institute of Technology Department of Marine and Environmental Systems Marine Field Project TO: FROM: RE: Dr. Stephen Wood, P.E. Program Chair, Ocean Engineering Department of Marine and Environmental Systems Florida Institute of Technology 150 West University Blvd. Melbourne, FL Steven Meyer Sanjukta Misra John Velasco Marine Field Project Final Report: Wave Glider DATE: July 19, 2012 Dr. Wood, Please review the attached final report for the Ocean Engineering Wave Glider team for the 2012 Marine Field Projects. The report details the motivations for the Wave Glider project, basic theory and background information, all procedures, designs, engineering specifications, testing and deployment results. The project and report have been the individual designs and work of the team and any supplemental material has been referenced.

2 Marine Field Project 2012: Wave Glider Prepared for: Prepared by: Dr. Stephen Wood, P.E. Program Chair, Ocean Engineering DMES Steven Meyer, Student Sanjukta Misra, Student John Velasco, Student 19 July 2012

3 FLORIDA INSTITUTE OF TECHNOLOGY [Acknowledgements] We would like to thank Dr. Wood and the rest of the DMES faculty for their help and support during the duration of this project. We would also like to extend thanks to the other senior design teams including NARWHALES, TURTLES, and the Wave-Energy team, the machine shop faculty and the Florida Institute of Technology for their help. We would like to give Matt Jordan special thanks for working out the electrical system.

4 Table of Contents List of Figures... 5 List of Tables... 5 List of Abbreviations Executive Summary Introduction... 9 Task... 9 Estimated Time... 9 Start Date... 9 Team member Role Topics Background Historical Background Liquid Robotics Wave Glider Procedures Customer Requirements Preliminary Designs Engineering Specifications and Computer Models Function Decomposition Structure Construction Results Discussion Conclusion Recommendations References Appendices Safety Report and MSDS Project Description Hazard Analysis

5 Human Safety Analysis Failure Modes and Effects Analysis List of Figures Figure 1: Challenger Expedition (10) 12 Figure 2: Data Buoy (13) 13 Figure 3: AUV on mission (16) 15 Figure 4: Military AUV (5) 16 Figure 5: MIT s Odyssey II (13) 17 Figure 6: Basic Design Patent (18) 19 Figure 7: Autonomous Steering Setup (18) 19 Figure 8: How the Wave Glider Moves (15) 20 Figure 9: Wave Glider on its mobile platform (6) 21 Figure 10: PACX mission from San Francisco to Hawaii (12) 22 Figure 11: Wave Glider Specifications (9) 22 Figure 12: First Float Design 24 Figure 13: Second Float Design 25 Figure 14: Intermediate Designs for Comparison 25 Figure 15: Simple Designs for Testing 26 Figure 16: Inductive Mooring System (17) 28 Figure 17: Inner foam of the float 29 Figure 18: Final View of Fiberglass Float 29 Figure 19: Wing System Design 30 Figure 20: Wing System Design 30 Figure 21: Harken Winch for Wings (11) 31 Figure 22: Rudder Design and Ideal Angle of Attack 32 Figure 23: Rudder design in Pro-E 33 Figure 24: Coordinate Plot for Rudder Design 33 List of Tables Table 1: Project Timeline... 9 Table 2: Team Members and Responsibilities Table 3: PacX Routes taken by Wave Gliders (9) Table 4: Surface Component Specifications Table 5: Wing Specifications

6 Table 6: Winch System Specifications Table 7: Rudder Calculations Table 8: Rudder Motor Options

7 List of Abbreviations DMES FIT ADCP CTD NOAA NDBC NWS AUV ROV Department of Environmental Systems Florida Institute of Technology Acoustic Doppler Current Profiler Conductivity, Temperature, and Depth National Oceanic and Atmospheric Administration National Data Buoy Center National Weather Service Autonomous Underwater Vehicle Remotely Operated Vehicle 7

8 1.0 Executive Summary The purpose of the Wave Glider project was to increase the efficiency and functionality of Liquid Robotics wave glider. The 2012 Wave Glider Senior Design project focuses on the optimization and modification of the current Wave Glider built and designed by Liquid Robotics in Sunnyvale, CA. The Wave Glider is an autonomous unmanned vehicle (AUV) which uses the power of the ocean to propel itself: a technological leap from typical AUVs powered by motors and buoys with expensive mooring systems. The objectives of the project included analyzing the current wave glider design to make it faster and more maneuverable. Initial design changes involved figuring out how to make the surface instrument float in different directions with respect to the subsurface propulsion wings. Another objective was to make the depth of the subsurface propulsion adjustable from 10 to 150 feet. With consideration to the material used for the system, a complete safety report was made and followed for all construction procedures. Analysis of fluid flow around the surface platform and subsurface propulsion system was conducted to ensure an efficient design with less drag acting on the structure. The overall design changes make the system more adaptive to different conditions while maintaining the simplicity of the system and its deployment. 8

9 2.0 Introduction Oceans cover over 71% (19) of the planet s surface. Traversing the oceans to record data is very important for keeping track of meteorological and oceanographic phenomenon. A new way to explore the oceans is needed. With improvements to current exploratory systems, a safer and more efficient method can be achieved. The motivation for the senior design project Wave Glider came from the team members desire to replicate the wave glider designed by Liquid Robotics and enhance some of its aspects to make it more practical and reliable. The team members wanted to make various improvements to the mechanism of the glider that would make it possible to collect a more diverse range of data and use a wide variety of instruments. The oceans cover 70% of the Earth s surface but majority of the ocean is yet to be explored. However, new technology is being designed to explore the dark seas and unmanned vehicles have been successful by the use of computers and technological advancements. The Wave Glider project focuses on a prototype of the glider designed by Liquid Robotics and the enhancement of its features, making it capable of changing the length of the cable by remote operation and having the capacity to employ more instruments with the help of Inductive Mooring. Table 1: Project Timeline Task Estimated Time Start Date Design Wave Glider 3 months January 10th, 2012 CNC Foam cutout 1 week April 4th, 2012 Construct model Drag Test 9

10 Task Estimated Time Start Date Instal remote-control mechanism Pressure Housing 2 weeks 3 weeks MFP Cruise 3 days June 6th, 2012 Testing of model Senior Design Symposium 1 day July 18th, 2012 Final Report The Wave Glider team uniformly decided on a unique system in which each member would work on their concentrated skill and area of interest in ocean engineering and then share with the team the progress of their specified task. Steve Meyer was chosen as the team leader and was placed in charge of the design of the hull and the pulley mechanism while John Velasco was in charge of designing the wings and rudder of the Glider. Sanjukta was put in charge of the electrical circuits dealing with the solar panels and the remote operation of the winch system. Each team member contributed while writing the assigned reports. Table 2: Team Members and Responsibilities Team member Role Topics Steve Meyer Team Leader Hull Designer Naval architecture Sanjukta Misra Electronics Designer Underwater technology John Velasco Wings Designer 10

11 The Wave Glider is a surface vehicle with an attached sub-surface wing system. The wing system is comprised of six individual wings that adjust to the current, speed, and direction of passing waves. This system propels the surface component forward, negating the need for a motor. The Wave Glider can be programmed for travel or to keep station at a certain location, which is hopeful in the need for replacement of buoys with expensive mooring systems. The Wave Glider has instruments on the surface component that can be customized for ADCP and CTD measurements, passive monitoring of marine life, and other commercial and defense applications. The instruments are powered by solar panels on the surface component, making the Wave Glider a self-sustaining vehicle. The vehicle transmits data to land in real-time sequence, allowing for accurate and easy monitoring of the vehicle s trip and the data collected. The goal of the 2012 Senior Design project is to optimize and modify certain aspects of the current Wave Glider design. Through research, collaboration, and use of modeling software for new designs, several aspects of the original Wave Glider were altered to reflect the group s own engineering intuition with hopes of improving the current model. The hull (surface component) design was modified, along with the design of the wing system (subsurface component). The new wing system is designed to be sleeker, more streamlined, and have a greater wing area with more flexible wings. The system was designed with the notion of creating a smoother ride for the vehicle with less jerking motion from the waves. Another modification is the attachment of the wing system to the surface component of the vehicle. The current model has a 7-meter tether connecting the two components. This has been modified with a retractable cable that allows the wing system to glide at a range of depths. The wiring of electronics has also been modified to allow for an adjustable rudder on the subsurface wing component. 3.0 Background 3.1 Historical Background Gathering data from the seas has been a focus since The HMS Challenger set out between 1872 and 1876 to gather information on ocean temperatures, chemistry, currents, 11

12 marine life and seafloor geology. The Challenger s first voyage set off from England and traveled through the Atlantic Ocean around the Cape of Good Hope. It traveled though the Antarctic Circle, the Indian Ocean, and the Pacific visiting New Zealand, Australia, and the Hawaiian Islands before returning back to England in (4) Figure 1: Challenger Expedition (10) The Challenger discovered the Marianas Trench and the Mid-Atlantic Ridge. It also revealed the first outline of the Atlantic Ocean. From data provided by the Challenger, scientists were able to map some of the currents and temperature distributions. The discoveries of the Challenger paved the way for studying the oceans and led many other countries to take interest and start other expeditions. (4) An American scientist, Mathew Fontaine Maury, noticed patterns in all of the data. From this data he was able to make charts of the ocean currents and wind patterns allowing captains to plan the best routes for travel. In return Maury requested ships to keep logs of data and throw bottles with notes overboard. By using the location of the found bottles and additional data Maury was able to create more detailed patterns of ocean currents. (4) In the late 1800s into the 1900s, Prince Albert of Monaco used a method similar to Maury s method to figure out the Gulf Stream s location and travel as it traveled along the Eastern seaboard of North America and across the Atlantic to Europe. Prince Albert determined that the Gulf Stream split into two currents and one traveled to the United Kingdom and one headed south towards Spain and Africa before heading west again. Prince Albert s information allowed authorities to predict where mines would drift in World War 1, giving them enough information to find and disarm them. (4) 12

13 Technology has led to a new era in ocean exploration in which ships are not needed. Long term observation can be taken using many sensors and instruments to make continuous measurements of many ocean properties. The data can then be transmitted to scientists through underwater cables linked to moored buoys and transmitted to satellites in real time. (4) The three most common methods of getting data are remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and buoys. The use of these instruments has greatly increased the reach of oceanographers in the line of research and knowledge of the oceans. (4) Buoys are one of the most common systems for obtaining data. They measure and transmit data automatically and transmit them in real time through different systems. The observations from buoys have led to significant advances in modeling and understanding global weather and climate systems on every space and time scale. (3) Buoys are one of the most cost effective means for obtaining meteorological and oceanographic data. Two types of buoys exist. Depending on the needed application, a drifting buoy or a moored buoy can be used. (3) Figure 2: Data Buoy (13) Drifting buoys are generally attached to an anchor or a drogue. They are easy to deploy and can measure the atmospheric and ocean conditions for an average of 18 months. They have been around since the 1970s and are still being used currently. One type of drifting buoy is a 13

14 Lagrangian drifter which measures the velocity of currents at the depth of its drogue while also collecting surface and other subsurface measurements. The Lagrangian drifter was standardized in 1991 to provide reliable data. (3) Moored buoys are stationary and do not move. They are generally much larger, with some of them being over 12 meters in breadth. They serve forecasting needs, record surface measurements including sea surface temperature and salinity, record subsurface measure past 500 meters in some cases, and also serve maritime safety needs. The buoys are very difficult to deploy due to the size, and they also require a robust mooring system to keep them from setting adrift during times of large waves and stormy conditions. These buoys are also very expensive due to their service needs and the bulky materials required for their construction. (3) Two different types of moored buoys exist. Tropical moored buoys are set up in large arrays and measure large scale phenomenon including El Niño, the Southern Oscillation, and the North Atlantic Oscillation. These show annual variability in global climate changes. The other type of moored buoy is known as a wave buoy. Wave buoys record the free surface of the waves, allowing waves to be models. They measure the frequency, amplitude, height, period, and celerity of waves. The wave buoys can incorporate data to predict storms and changes in offshore wind patterns. (3) The AUV definition comes from the oil and gas industry. The oil industry developed the first conceivable untethered underwater vehicle which was a self-propelled torpedo in The more traditional history begins with Dimitri Rebikoff s Sea Spook in The next AUVs created were the Applied Physics Laboratory s Self Propelled Underwater Research Vehicles developed in 1963 and 1973, followed by the Unmanned Arctic Research Submersible (UARS) in AUV developments after 1973 were slow until the late 1980s when significant advances in energy, computing, and navigation were developed. Advanced AUVs started appearing, funded primarily by the US Navy, and Applied Remote Technology s XP21. During the 1990s major advances came through in computers, batteries, and sensors, leading to Woods Hole Oceanographic Institute s Autonomous Benthic Explorer and Florida Atlantic University s Ocean Voyager. The AUV industry has since branched from military use and the ocean exploring community into the commercial offshore survey market (14). 14

15 Figure 3: AUV on mission (16) AUVs are programmable robotic vehicles that drift, cruise, or glide through the ocean. They are untethered and loaded with actuators, onboard sensors, and in some cases, onboard intelligence. They do not need any real time control. The AUV can be programmed to go anywhere and record data throughout the entire journey or only at certain points. Some AUVS can make their own decisions based on the data that they receive and interpret along the way. They are very simple to deploy and easy to control from a ship or land-based control center. AUVs communicate periodically through underwater beacons or real-time via satellite. (7) The main reason for using AUVs is that they are the most cost effective way to obtain a large series of data. AUVs usually offer the best or only option for many missions due to the low cost and high level of safety. They are the newest technology for obtaining data and many advancements are still underway. The lack of a tether provides a much more mobile vessel that requires a smaller crew, easier deployment, and little to no vessel time. The only downfalls include the necessity of the vehicle s ability to efficiently and safely act on its own since there are no humans to interfere in the case of a problem, and also the difficulty of underwater transmission for submerged AUVs; they must be able to act completely independent from human involvement at times. (7) AUVs have not been proven to be cost effective at abyssal depths. Three AUVs have gone to depths greater than 6000 meters, including the Naval Ocean Systems Center s Underwater Search System (AUSS), the French vehicle EPAULARD, and the Soviet Union s MT-88. The deep water AUV systems proved to be too expensive in terms of equipment and operational costs due to the complexity and size required to reach those depths. (7) 15

16 A large portion of research and development in the United States has been for military purposes. Vehicles weighing an excess of 6 metric tons have been built. They cost millions of dollars and require large support vessels and have limited handling capabilities. The Navy s main concern is littoral warfare, so AUV research and development has moved away from the large expensive systems and shifted towards small vessels that are designed for shallow water use; the smaller AUV systems are relatively low cost and have stealthy abilities. (7) Figure 4: Military AUV (5) Small AUVs were previously thought of as impractical because they did not have the capacity, durability or range that was required. In recent years the scientific community has seen a need for small, high performance, low cost AUVs. The lower cost of the AUVs allows scientists to deploy greater numbers of them. This results in a larger number of data points being collected for analysis. The cheaper AUVs also allow more dangerous missions to be attempted without the fear of losing extremely expensive pieces of equipment. (6) In 1991 and 1992 MIT Sea Grant College Program s AUV Laboratory constructed a vehicle called the Odyssey; it underwent trials in the Atlantic Ocean off of New England before being deployed from the Nathaniel B. Palmer off of Antarctica in early The work of the Odyssey was supported and monitored by the Sea Grant College Program, MIT, the National Science Foundation, and the National Underwater Research Program. Because of the success of this program, a second generation of the Odyssey was created: the Odyssey II. The Odyssey II also proved to be very successful in autonomously taking measurements up to 1,400 meters under Arctic sea-ice. (1) 16

17 In 1995, four vehicles were built by the Office of Naval Research and named the Odyssey IIb. The four new AUVs were loaned to Woods Hole, the Navy s Research and Development center, and Electronic Design Consultants in Chapel Hill, NC. The vehicles were all very simple to use and conducted many experiments over the course of a month. Two of the Odyssey II-b vehicles were used to conduct studies on the dynamics of frontal mixing in the Haro Strait and were equipped with water quality sensors, a side-scan sonar, and water current profilers. All of the Odyssey II-b vehicles were recovered successfully after performing many dives. (1) In 1997 the Sea Grant College Program s AUV lab primarily focused on developing an Autonomous Ocean Sampling Network that would collaborate the data collected by many AUVs over many trials. Between Woods Hole Oceanographic Institute s system that allowed the AUVs to dock, recharge their batteries, and download data, and the additional mooring and communication systems put in place, the Ocean Sampling Network became a reality by The integrated system conducted research and searches all over the oceans and proved to be very successful before being disbanded in August of The Odyssey II-c was developed after the Odyssey II-b. The Odyssey II-c was mechanically the same as the Odyssey II-b but was upgraded with new computers, sensors, and software. The Odyssey II-c was much more advanced and was aimed towards the commercial market. The main commercial application of the Odyssey II-c was aimed at the offshore oil and gas market for exploration and surveying to find new deposits. (1) Figure 5: MIT s Odyssey II (13) 17

18 Bluefin Robotics was developed in 1997, and opened a manufacturing facility in The commercial industry soared with the growth of Bluefin Robotics. The transition led to an increase in AUV technology and yielded a mobile network for ocean observation. (1) AUVs are usually shaped similar to a torpedo. They can be buoyancy driven, driven by a battery with a propeller, a motor with a propeller, wave energy driven, or solar-driven in conjunction with batteries and a propeller. (14) 3.2 Liquid Robotics Wave Glider Liquid Robotics has developed a completely autonomous vehicle that draws all of its power from the sun and the sea. The propulsion works primarily off of the buoyancy of a surface float that pulls the wings upward, and the negative buoyancy of the wings causing them to sink. The up and down motion of the wing system through the water and the wings freely pitching cause the wings to excel forward, pulling the float by its 22-foot tether. The Wave Glider therefore does not need to be fueled. The electrical system on board is powered by solar panels on the floating surface component of the system. The solar panels power the remote control and onboard instruments that allow the Wave Glider to constantly monitor and test different aspects of the ocean. (9) Liquid robotics has patented the system which comprises the fin system, tether, and float. The patent number , titled Wave Power. The subsurface wing system, called the swimmer, has a frame on a longitudinal axis, and fins that rotate about the axis. The fins are laminar and the frame consists of a rigid bar. The fin system is comprised of 3 to 10 identical laminar fins. The fins are generally elastically deformable. The original claim is that if the system is placed in wave bearing water the vertical motion will result in the fins moving about their axis and horizontal motion being achieved. The swimmer is attached to a tether in front of the center of drag. The steering actuator is a rudder that is attached to the float. The three parts work together as a unitary body. The float contains a system for satellite communication and tracking, which allows for steering using the rudder. The tether comprises of a device to detect twisting and another device to correct the twisting. 18

19 11. Float 21. Swimmer 31. Tether 111. Float Body 112. Solar Panels 113. GPS Receiver 114. Antenna 115. Electronics Box 116. Rudder Figure 6: Basic Design Patent (18) 211. Body 212. Nose Cone 213. Fin 214. Fin System 215. Electrical Passthrough 216. Batteries 217. Control Electronics 218. Rudder servo mechanism 219. Rudder control passthrough 220. Rudder Control 221. Rudder Arm 222. Rudder 311. Tensile Member Figure 7: Autonomous Steering Setup (18) 19

20 Figure 8: How the Wave Glider Moves (15) Because the Wave Glider offers a cheaper, more economical, and environmentally sound method of monitoring the seas compared to other AUVs, scientists are able to obtain much greater amounts of information at much lower costs. The wave glider is commonly fitted with an Acoustic Doppler Current Profiler (ADCP), an acoustic modem, vessel automation identification system receivers, passive acoustics for animal monitoring, and a few other instruments to measure meteorological and oceanographic conditions. (9) The Wave Glider is fit to replace many AUVs for a variety of applications. The government could use the Wave Glider for intelligence, surveillance, monitoring exclusive economic zones for fishing, and other economic resources that are very important to coastal countries. Monitoring of coastal waters normally requires large amounts of expensive surveillance. The Wave Glider does away with the large crews required for monitoring, cutting down the costs substantially. The Wave Glider also has a variety of applications in the commercial sector. They can be used to find and research resources and fisheries at a fraction of the cost of other methods. Since the Wave Glider can either be programmed for a journey or to keep station, it is looked at as an alternative for expensive moored buoys. (9) Because the Wave Glider is relatively inexpensive, many of them can be deployed to monitor the vast oceans. Wave gliders have the capabilities of a 3-meter moored buoy but are mobile with real-time data transmission; this means the Gliders have no need for ship time, mooring 20

21 lines, and at-sea servicing. Because the Wave Gliders are mobile they can be deployed from any port or harbor, complete their long missions, and return back to any port or harbor to be serviced. (9) Figure 9: Wave Glider on its mobile platform (6) The first Wave Gliders were delivered in In 2011, NOAA s NDBC deployed the first operational Wave Gliders to monitor real time observations throughout the Gulf of Mexico. They also released a second Wave Glider to record tsunami observations and data. The Wave Glider has helped the NDBC enhance maritime safety, coastline inundation, oceanographic and meteorological observations. (9) Liquid Robotics has proved the success of the Wave Glider with a 60,000-kilometer journey called PacX. Four Wave Gliders traveled from San Francisco to Hawaii and then broke into two pairs. One pair proceeded to Australia while the other traveled to Japan. Table 3 describes the record-breaking journey and PacX routes. (9) 21

22 Figure 10: PACX mission from San Francisco to Hawaii (12) Figure 11: Wave Glider Specifications (9) 22

23 Table 3: PacX Routes taken by Wave Gliders (9) Glider Mission Route Description Mission Objective and Results Red Early January 9 18, This successful engineering test demonstrated the Wave Flash Endurance day mission to Glider s ability to operate in offshore waters over extended Trial circumnavigate the periods. Circling Hawaii provided exposure to a variety of island of Hawaii. conditions. Average speed: 1.57 knots. Maximum Sea State: 10 foot waves, 15 knot winds Red Extended August 13-September This successful engineering test demonstrated the Wave Flash Coastal 23, day Glider s ability to operate in offshore waters and varying Voyage mission from Monterey conditions. The test concluded after the vehicle was Bay to Alaska. Average successfully passed through a severe storm and sea state 6 speed: 1.5 knots. conditions. Maximum sea state: 20 foot waves, 40 knot winds Stripes Offshore Loiter offshore Hawaii, Demonstrated the wave gliders exceptional endurance. Hawaii launched December 16, Exposed a single wave glider to ocean conditions for over one 2008 year. After being brought in, slight maintenance was done and the wave glider was redeployed. Red Monterey April, 2010, test Test to evaluate the Wave Gliders ability to take Flash Bay operations measurements with a CTD. The test was successful, demonstrating the Wave Glider s ability to take oceanographic surveys at the air-sea surface. Honu Hawaii to April-June, 2009, 82 Demonstrated the Wave Gliders ability to cross long distances and California day trip from Hawaii to in the open ocean. The Wave Gliders returned in excellent Kohala San Diego, over 2500 condition miles 23

24 4.0 Procedures Extensive background research was done on the current Wave Glider design and general engineering specifications of AUVs. After coming up with initial ideas and design objectives to improve the current model, the task of figuring out how to employ such changes on the current model so that the system remained mechanically sound was undertaken as a collaborative effort. 4.1 Customer Requirements The Wave Glider must work as efficiently as the one Liquid Robotics created but must be lighter, easier to deploy, and have wings that reach adjustable depths. The lighter weight can be obtained by creating a lighter float that is near hollow, and a severe reduction of materials used in the wings. The forces on most of the materials are small enough to be able to use much less material while retaining an appropriate safety factor. The Wave Glider must be deployable from the Thunder Force or similar ship. This means that the Wave Glider must be able to be lifted by a winch and deployed or recovered easily. Control of the rudder and the winching systems to make the wings adjustable must be via remote control from the Thunder Force. All power must be obtained from wave energy and solar energy to power all of the systems on the Wave Glider. It should be able to be deployed and functioning for a minimum of a few hours. 4.2 Preliminary Designs Figure 12: First Float Design 24

25 Figure 13: Second Float Design Figure 14: Intermediate Designs for Comparison 25

26 Figure 15: Simple Designs for Testing After reviewing all of the designs for the surface component of the system, it turned out that the machine shop does not have machinery capable of cutting out extremely complex shapes. The simple shapes encountered excessive drag while moving through the water so some intermediate shapes (between too simple and too complex) were considered. The intermediate shapes offered the best combination of buoyancy, platform area, stability, efficiency, and ruggedness. Hydrodynamic calculations were made to be sure of the correct choice of shape and hull for the surface float. The wings were designed to remain stable while adjusting to different depths, which is why weight was added to give the subsurface system negative buoyancy. The wing system was also designed so that when the winch rescinds the cable toward the surface float, pulling the wings upward, it will not pull the float underwater possibly damaging some of the instruments. The design calls for much thinner materials making it lighter and more flexible. The wings will also pitch 26 degrees in motion, as this angle proved to be the best angle of attack for creating forward propulsion from vertical motion. The winch system was designed so that the wings could be retracted to fit directly underneath the float for deployment and retrieval; this provides a very simple and safe deployment and ease of transport compared to the original Wave Glider. The current Wave Glider is on a stationary tether that is not adjustable or retractable, making it very dangerous to deploy and retrieve in high seas. The retractable wings would also make it simpler to deploy the Wave Glider from shallow water such as that of a harbor or bay with shallow depth. The wings 26

27 could also be integrated at a later date so that they would be able to adapt to the water column which would increase the overall speed or station-keeping abilities. The rudder is designed to create a small turning radius while inhibiting the forward motion as little as possible. The rudder is driven by a motor encased in the wing system. The electrical system will run from two solar panels that constantly charge a battery. The setup was designed because the winch draws more power than the solar panels can deliver. The battery will be charged from the panels and have the electrical output to drive the winch and rudder when needed. Direct cable connections were generally the preferred choice for underwater to surface data transmission but the advancement of technology has made it possible to use new methods like inductive mooring that allows up to 100 instruments to be positioned or repositioned at any desired depth. The Wave Glider team incorporated the idea of inductive mooring in the proposed design to make it more economical and flexible. The Inductive Mooring system employs transformers to couple data to the mooring cable and sensor data is applied to the primary winding of a toroidal transformer. The mooring cable is passed through the toroid forming a single turn secondary that conveys the data to the surface. The toroids can be conveniently split into halves so that they can be clamped around the cable without the need to thread the cable through. The data transmission is done with the help of a high frequency carrier onto which the data is impressed. If a bigger budget could be acquired for the Wave Glider project, the Preferred IM configuration would be used. In this configuration, the ends of the mooring cable are grounded to the seawater, which causes a current to flow through the mooring wire and seawater. The Inductive Cable Coupler (ICC) senses this current and provides a voltage to the Surface Inductive Modem. The instruments can be easily clamped on the mooring cable at any point, without having to cause a break in the cable at the instrument position or having to provide any electrical connection between instrument and cable. 27

28 Figure 16: Inductive Mooring System (17) After researching an inductive mooring system for the Wave Glider, it was determined that such an apparatus was far too expensive and advanced to be purchased and used for the Wave Glider. 4.3 Engineering Specifications and Computer Models Table 4: Surface Component Specifications Width 30 Height 6 Length 52 Weight 140 lbs w/ winch and battery Buoyancy 290 lbs 28

29 Figure 17: Inner foam of the float Figure 18: Final View of Fiberglass Float Table 5: Wing Specifications Width 43 Height 18 Length 72.5 Thickness Bearings Bones Ceramic Red Bearings Stabilizing Material 10 lbs Lead Main Material Aluminum Weight 47 lbs total 29

30 Buoyancy Max Drag (V=1m/s vertical) 32 lbs 136 lbs Figure 19: Wing System Design Figure 20: Wing System Design Table 6: Winch System Specifications Model Harken Rewind Radial Electric Winch Height 8.5 Width 7.5 Radial Draw 12 volts/700 Watts Cut off Power 1874 lbs Weight 26.5 lbs 30

31 Figure 21: Harken Winch for Wings (11) Javafoil was used to design and analyze the rudder to be used on the subsurface wing component. Analysis of the rudder was critical because the right motor for the control of its movement had to be determined. The motor needs to have enough power to control the rudder against the drag and forces that act on it without wasting any power or taking too much energy from the battery. Table 7 entails the forces acting on the cambered plate of the rudder at angles of attack of 45, 30, and 20. The Reynolds number used for calculation was 40,000 and the area of the rudder is m. Table 7: Rudder Calculations Angle of Attack Coefficient of Lift ( Coefficient of Drag ( Force (Lift) [N] Force (drag) [N] Turning Torque [kg-m] Turning Torque [oz-in] The coefficients of lift and drag were obtained through the use of the modeling software Javafoil. Using an aluminum plate for the rudder limited the Reynolds Number to 40,000 which is the highest number that can expected for optimum performance with its simplistic shape. The area of the rudder was determined by designing an appropriate body-to-rudder ratio and the performance of the designed area can only be fully analyzed through model testing. Calculations for drag forces and lift forces on the plate were determined by the following equations: 31 Equation 1

32 Equation 2 ( Equation 3 Figure 22: Rudder Design and Ideal Angle of Attack 32

33 Figure 23: Rudder design in Pro-E Figure 24: Coordinate Plot for Rudder Design Due to the calculations in Table 7, the motor needed to control the rudder must have the specified turning torque power to be sufficient for use in the system. After determining that a servo motor should be used instead of a stepper motor, due to the capabilities needed of the motor and its ease of use, a few options were considered: 33

34 Hitec HS-5086WP Waterproof Micro Servo USD $49.99 The Hitec HS-5086WP Waterproof Micro Servo features 38.9 oz-in 4.8 Volts and 44.4 oz-in 6.0 Volts. The speed is 0.18 sec/60 degree (4.8 Volts) and 0.15 sec/60 degree (6.0 Volts). Hitec HS-5646WP Waterproof, High Torque Digital Servo USD $54.99 The Hitec HS-5646WP Waterproof, High Torque Digital Servo features 97.2 oz-in 4.8 Volts and oz-in 6.0 Volts. The speed is 0.26 sec/60 degree (4.8 Volts) and 0.22 sec/60 degree (6.0 Volts). Table 8: Rudder Motor Options Servo Model HS- 5086WP HS- 5646WP Speed [sec/60 ] Torque [oz-in] Size [in] Weight [oz] Gear Type 0.18 (4.8V) 38.9 (4.8V) 1.22 x 0.60 x Metal 0.15 (6.0V) 44.4 (6.0V) 0.26 (4.8V) 97.2 (4.8V) 1.65 x 0.83 x Metal 0.22 (6.0V) (6.0V) If only considering a 20 turn radius, or angle of attack, then the ideal servo motor to choose would be the HS-5086, not only because it meets the torque requirements of the rudder but it is smaller and lighter than the HS Taking into account whether or not the rudder will actually be limited to a 20 angle of movement, it would be safer to go with the HS-5646 but a sacrifice in space is needed. Overall, the HS-5086's torque capacity meets the needed power for the rudder from the calculations in Table 7, but gives no room for safety. For a small increase in size the HS-5646WP in any circumstance is the safest option to prevent failure in the rudder component. 4.4 Function Decomposition Structure for Original Design The float will be constructed of high density closed-cell foam and vinyl ester resin fiberglass. The fiberglass will be laid over the frame of the foam. This will create a rigid float that will be very durable and not susceptible to salt water. The winch being used will be one made for lifting sails on sailboats; it is very durable as long as the electrical components are encased. 34

35 The wings will be made out of a marine-grade aluminum that will sustain for many years in salt water. The bearings being used are rust-resistant ceramic skateboard bearings that will last long enough to test the Wave Glider. They have no record of being used in salt water but are the best bearings that can be afforded. The bearings can be replaced with a very small amount of work if failure were to occur. The material used to connect the winch to the wings will be a 5/16 spectra fiber rope that has a tensile strength of 3,663 pounds. The rope is very tough, flexible, and resistant to the salt water environment. All electrical equipment will be covered by attached plastic to keep the system watertight. The motor for the rudder will be enclosed in the wing system and sealed with a gasket sealer to ensure that the motor to control the rudder remains dry at all times. 4.5 Construction Float: The float was constructed through many steps. The first step was obtaining the high density foam that was used as the core. The original plan was to have the float core cut on a CNC (computer numerical control) router. Due to time constraints the core had to be constructed by hand. The foam was layered into two layers and cut to 52 x30 x6 using the band saw at the Florida tech machine shop. The next step was using a routing bit with a mill to get the rough dimensions of the float and cut out the center grove. The foam was then sanded to smooth dimensions using 40,80, and 120 grit sand paper. 35

36 Figure 25-Smoothing out the foam core To make the foam lighter a 1.25 diameter speed bit was used to drill deep holes. After the foam core was completed an air hose and compressed air was used to strip the core of all dust. The core was then coated with two layers of fiberglass cloth and vinyl ester resin. The fiberglass clothe was a type of e-glass with a 24 ounce specification. Figure 26-Fiberglass curing at FIT machine shop Once the fiberglass was cured a grinder was used to remove all of the sharp edges, followed by sanding. The bulk of the sanding was done with sixty grit sand paper on a belt sander with 36

37 the rest being done with compressed air rotary sanders and 120 grit sand paper. Once the fiberglass was smooth batches of resin were mixed and coated onto the float to smooth out the model. This process was repeated four times for the top and bottom of the float. The float was then sanded again. I final coat of west systems 207 epoxy resin was coated on and sanded with 320 grit sand paper on the rotary sanders. Figure 27-Applying layers of resin for smooth surface The next step was using one quart of West Marine white gel coat with a tube of West Marine blue coloring agent. The coloring agent came in a tube the mixed 1 tube of coloring agent to one quart of gel coat. The final result was a baby blue color. In order to increase visibility stencils were constructed and FIT-DMES-OE was painted on the port and starboard sides. On the bow of the wave glider a wave was stenciled on along with our project name in script, Radical-V. 37

38 Figure 28-Bow stenciling and gel coat color The float is constructed out of high density foam, fiber glass, vinyl ester resin, epoxy resin, and gel coat. The high density foam is susceptible to sun damage but is completely enclosed. The vinyl ester resin is water resistant but not waterproof. To deal with this we put a layer of epoxy resin on and two layers of finishing gel-coat. The float should have a service life of at least 30 years assuming no structural damage is encountered. If any structural damage is encountered it could be fixed by anyone experienced in fiber glassing. Wing System: The Wing-Frame was pre-fabricated by Alro to 43 x0.375 x18 (wxlxh) with an extra two 43 x0.375 x4 Aluminum plates that would clamp together parallel to the top of the system to add strength to the structure. Six 1 holes (evenly distributed along the width) were drilled through the three eighth-of-an-inch aluminum plates that would later serve as casings for dual ceramic bearings. Twelve identical aluminum wings were also prefabricated by Alro to a measurement of 62.5 x4 x

39 Figure 29-Pre-fabriscated parts from Alro in Orlando, Fl Six 5/16 Aluminum rods were later welded to the wings to keep them together through the bearings. Originally the wings were set for an extra 10 in Length, but after a reconsideration in facilitating portability the extra length was dismissed to create a more modular design that would fit with the float. In order to limit the angle of attack of the wings two aluminum rods were added above and beneath every wing to limit their movement to 30 degrees (after approximately 28 degrees there is more resistance than thrust). The wings were also modified near the base by cutting the edges so they wouldn t cause friction with the frame. An inch think hole was drilled through the top of the frame using the center of gravity as its location, an inch bolt would be passed through the hole so it could serve as a lifting point for the winch. Modifications of the frame for the rudder s motor were necessary, and in consequence, a perfect fit. On the tail of the wing-frame a detailed shape was cut through the three aluminum layers to serve as a casing to the motor. A stainless steel half inch screw was inserted a few inches below the motor s casing to serve as a second support for the rudder to relieve unnecessary axial stress from the motor. All welds and cuts received appropriate aftershave grinding. 39

40 Figure 30-Completed wings before priming and painting Winch: For mounting the winch on the Float, two sheets of aluminum were obtained and with the help of the band saw, the sheet was cut according to the desired shape and dimensions. The two sheets were then clamped together so that Bill, from the Machine Shop could weld them together. Figure 31-Connecting the aluminum plates 40

41 This was done so that the frame on which the winch is positioned would be strong and not buckle under the weight of the winch and give a more refined appearance to the Float. After the sheets were welded together, small holes were drilled along the length of the aluminum sheet so that it could be firmly attached to the Float with screws. Another piece of aluminum was placed diagonally across the square part of the bigger sheet. This was strategically done so that the winch could be placed in a manner that would not affect the balance the Float and cause it to tip in any particular direction. The winch was then bolted down to prevent its displacement due to large waves or any other sudden movement. A hole was drilled in the Float to allow the passage of the winch cable so that it can be attached to the Sub, which serves as a frame for the wings. Figure 32-Winch bolted to reinforcing plate 41

42 Battery: For the placement of the battery, a section of the Float was drilled out from the surface for a snug fitting. The section drilled out was however, larger than the battery size by a few centimeters so that the battery could be quickly removed in case of electrical issues. After the section was drilled out, a sander was used to create a smooth surface to enable the battery to be placed correctly. After the battery was properly placed, it was firmly glued using a spray foam to prevent it from being damaged due to sudden movements. Figure 33-Battery used for final project Solar Panel: For installing the solar panel on the Radical V, four small holes were drilled on the Float, corresponding to the pre-drilled points for mounting on the solar panel. Four rods were installed at those points so that the solar panel could comfortable balanced on the four rods at the four corners. RC Transmitter / Receiver: The RC transmitter / receiver used in the Radical V needed to be configured and Mathew Jordan helped to make the electrical connections and hook up the servos in the Radical V so 42

43 that it could be radio controlled. The electric circuit configuration in the winch control box had to be modified so that the servo could be installed in it to allow the radio-controlled up and down motion of the winch cable. Another servo was connected to the rudder in the glider part of the Radical V so that the rudder could also be operated by the transmitter. 5.0 Results Pool Testing Pool testing was conducted on both the float and the wings. The wings were tested independently from the rest of the system. The Florida Institute of Technology allowed for the parts to be tested in the pool located at South Gate. The wings were transported in a student s vehicle (Mallory Bonds 2007 Toyota Rav4). The Wings were tested by moving them up and down roughly one foot at a period of 3 seconds. The wings were successful in that the wings were able to provide a forward motion to themselves and a 180 pound student. Figure 34-Wing Testing The float was also tested in the pool. Radical-V and TURTLES met at South Gate pool where the float was to be tested for stability, buoyancy, and durability. The float was tested under the load of a 180 pound student which is much larger than the weight that later went on the float. The float was then pushed and pulled across the pool to examine how it reacted with motion. The float maintained a steady course due to the pontoon style. Waves were also 43

44 generated using tubes and the float reacted extremely well in the choppy style water. Overall the pool testing of both the wings and the float went extremely well encouraging the unification of the system and testing it as a whole. Figure 35-Float testing with TURTLES Ocean Testing A 1998 Mercedes Benz ML320 (courtesy of Trier Perry) offered a perfect fit while transporting the wave glider to Melbourne Beach. Once arrived, two wooden beams were lifted by four students as they were hooked to the four lifting points on the float. 44

45 Figure 36-Transporting the glider for ocean testing On shore we had realized that a plastic gear had shred inside the rudder motor making it incapable of turning; the remote control was accidentally left turned on while the joystick for rudder control was pressed during the car ride, due to limited space the forced rudder was resisting to turn as it was already pressed against an object. Before we deployed the wing wave a short-circuit occurred in the receiver causing the winch to have a mind of its own, but the problem was resolved by manually controlling the winch. As the Wave glider was deployed students mounted their kayaks to keep a close view on the glider as it thrusted forward through the waves. Overall, the Ocean Testing was a complete success. The float kept its course and buoyancy as it sustained the nature of the ocean (1-2 foot choppy waves), and the submersible system attained its goal by continuously thrusting the float onward. For future Ocean testing, it is recommended that the aluminum rods be replaced by steel rods to prevent any accidental bending, and a more efficient waterproof casing must be used for the instruments on the float as ours had leakage. 45

46 Figure 37- Testing Radical-V in the ocean Comparison to the Original Wave Glider: The wave glider, designed by Liquid Robotics, Inc. consists of a fixed 6m (20ft) tether that connects the submerged glider and surface float. On the other hand, the Radical V has an adjustable tether due to the winch system installed on the surface float which makes it easy to deploy and retrieve. The Liquid Robotics wave glider weighs 200 lbs while the Radical weighs 170 lbs. This 30 lbs difference makes it easier to transport and deploy the Radical V. Also, unlike the Wave Glider which uses springs to restrict the movement of the underwater wings or fins, the Radical V has rods positioned at a specific angle to stop the wings from rotating too far. Since the rods are external, they can be repaired easily if any damage occurs. This design makes it more practical and cost-efficient in case of any malfunctions. 46

47 6.0 Discussion Many of the implications in the design came from a lack of time and money. The design phase was delayed and started two weeks behind schedule. Overall the team worked very hard splitting up the work and getting everything done on a fast timely basis. The construction of the float was difficult as most students do not have extensive experience working with the foam on a large scale and the fiber glassing. The foam core was supposed to be cut out at Structural Composites in Melbourne, Fl, but due to time constraints and the need to get the core built it had to be done by hand. This was done in very unconventional ways. All of the teams brainstormed how the core could be built and between the class ideas the core was built quickly and came out looking very good. The wings were going to be ordered as solid sheets of metal and cut to the dimensions that were needed. Due to the need for high tolerances and the time constraints the Radical-V team sent AutoCad drawings to Alro Metals in Orlando, Fl where all of the pieces were cut with a Flow Jet and delivered two days later. The parts came and were exactly what was needed allowing for the team to transition into the construction of the wings immediately. The wings system had to be altered. The wing blades were cut to a small size to provide less resistance and the original design was changed. The original plan was to use aluminum rods but they could not be welded to the wing blades without snapping. This resulted in resurfacing the wing blades and using steel rods. Since aluminum cannot be welded to steel each blade was bolted to the rods using three bolts. Overlooking the issues from welding and hitting that road bump resulted in the team developing a better system where the wings could be unbolted easily. The electronics proved to be too difficult for undergraduate students. The Radical-V team was going to install toggle switches to control the electronics until Matt Jordan, a graduate student in Dr. Woods Underwater Robotics Lab stepped in and set up the remote control to power the winch and the rudder. This saved the team a lot of time and proved to be effective. The pool testing went extremely well. With the help of other students and the permission of Florida Tech the float and wings were tested in Southgate pools. Everything worked out very smoothly. In fact, everything worked much better than expected for the first test trials. 47

48 After the pool testing the Radical-V team tested the wave glider in the ocean. It was transported in the back of a mid-sized sport utility vehicle proving the mobility of the system. The radio controls acted up and the system had to be tested by manually controlling the winch. It was later discovered that this occurred due to solder joints that broke. The problem is an easy fix and the system could easily be repaired and re-tested. The help of the TURTLES team was very appreciated on this day. The testing proved to be a large attraction with many people at Melbourne Beach inquiring about the project, ocean engineering, and Florida Tech. Figure 38-Spectators inquiring about Radical-V 48

49 7.0 Conclusion The Radical-V wave glider progressed extremely far over the six months that it was conceived and built. Overall the project was a great success for the first year. Very few road blocks were hit during the duration of the project and all problems encountered were quickly resolved and repaired. This project has the capabilities of providing the next generation of data acquisition through its light, modular, simplistic, and reliable base. This project will be very successful in the years to come and should change the face of the current technology. Figure 39-Radical-V in the symposium 8.0 Recommendations For future students working on this project many things could be done to improve the project. The first and foremost would be to develop a plastic molded float. The problem with the fiberglass is that it needed a core and multiple layers of resin and glass in order to make it durable enough to withstand slamming into other objects. The plastic is much more flexible then the fiberglass which is more important then the rigidity of the fiberglass. This would allow for a much lighter float, which would allow for more instruments and a smaller float size. The mounting frame for the winch could also be changed depending on the winch used. The winch we used was rated for 2000 pounds and was rather bulky. A more compact, lower draw, and more waterproof sailing winch could be used if it fit in the budget. The required winch strength is 200 pounds, ten times less then what we used. A smaller winch would allow for a 49

50 smaller battery, and a smaller mounting plate, further reducing the weight and increasing the mobility and efficiency of the glider. The electrical system should also be improved. All of the electronics should be placed in a small, neat looking electronic housing within the float. The wires should be increased in size as some of the solder joints came apart before testing limiting the testing of the project. The battery that powers the winch should be changed to the main battery with a voltage reducer instead of running off of a separate non-rechargeable battery pack. The most important electrical change would be a different electrical tether. This would allow the steel cable that supports the wings to not catch the Cat-5 wire that we used. Figure 40-Electronics The wave glider should be deployed on different days so the speed and performance of the wave glider could be analyzed in different wave height and period waves to establish possible routes and expected performance characteristics. Last off, the wave glider could also be set up to be completely autonomous. With some satellite communications and a GPS the wave glider could be set up and deployed for long periods of time under the control of Florida Tech students and faculty. The Wave glider should also be set up with instruments to observe oceanographic and meteorological phenomenon. 50