t rf, j remotely operated vehicle rov/auv ad … · ... (rov) reliability study was initiated in...

Click here to load reader

Post on 19-Jun-2018

216 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Report Number: MIS 8908001

    t rF, j REMOTELY OPERATED VEHICLE ROV/AUV

    AD-A240 672 RELIABILITY STUDY1 1111 I' HI PHASE II FINAL REPORT

    Kurt L. Smrcina / John Perry Fish

    Marine Imaging Systems, Inc.8 Otis Park DriveBourne, MA 02532

    September, 1989

    FINAL REPORTN00014-87-C-0728

    Prepared for:

    Office of Naval Research (Code 122)Department of the Navy800 N. Quincy StreetArlington, VA 22217 91-11147

  • faONT 0=CMV(ATION4 L' 2wlp . 2.4O9 g N

    'I S -l k ,L Assm Dm

    REMOTELY OPERATED VEHICLE (ROV) RELIABILITY STUDY; SEPTEMBER 1989SFINAL REPORT

    KURT L. SMRCINA; JOHN PERRY FISH MIS 89

    MARINE IMAGING SYSTEMS, INC.8 OTIS PARK DRIVE 'c u Qrmng "

    BOURNE, MA 02532 ' N00014-87-C-0728

    32. wq ~ D~S 4~ 1. tem & ftw~ue wmqjOFFICE OF NAVAL RESEARCH (CODE 122)

    DEPARTMENT OF THE NAVY FINAL REPORT800 NORTH QUINCY STREETARLINGTON. VA 22217

    ONR COTR CAPT. D. KOCZUR (202) 696-4713KURT L. SMRCINA (508) 759-1311

    A REMOTELY OPERATED VEHICLE (ROV) RELIABILITY STUDY WAS INITIATED IN TWO

    PHASES TO DETERMINE HOW ROVs CAN BE DESIGNED AND BUILT TO ACHIEVE ENHANCED

    OPERATIONAL RELIABILITY WHEN OPERATED DURING EXTENDED UNDERWATER DEPTOYMFN7.THE CONTRACTOR WAS TO EXAMINE THE TEGHNOLOGY USED IN THE DESIGN AND

    CONSTRUCTION OF REPRESENTATIVE ROVs IWHICH ARE CURRENTLY STATE-OF-THE-ARTAND DOCUMENT PROPOSED DESIGN OR CONSTRUCTION METHODOLOGY TO EFFECT HIGHRELIABILITY. THIS REPORT IS THE CONTRACT FINAL REPORT OF THE PHASE I

    STUDY EFFORTS AND PHASE II STATEMENT OF WORK (SOW) DEVELOPMENT.

    THE RESULTS OF THE PHASE I STUDY WERE COMPILED AND DETAILED IN THE STUDY

    REFORT (DELIVERED SEPARATELY). IT WAS RECOMMENDED THAT EFFORTS SHOULD BE

    INITIATED UP FRONT TO DEVELOP TECHNOLOGICAL APPROACHES AND DESIGN ANDMANUFACTURING CRITERIA TO ADDRESS THE LONG TERM RELIABILITY PROBLEMSIDENTIFIED IN THE STUDY. A PRIORITIZED LISTING OF RECOMMENDED THEORECTICAl

    AND EXPERIMENTAL WORK WAS DEVELOPED FROM THE STUDY RESULTS AND FORWARDEDIN THE FORM OF A PROPOSAL FOR PHASE II TASKING APPROVAL.

    REMOTELY OPERATED VEHICLES (ROV)

    AUTONOMOUS UNDERWATER VEHICLES (AUV)UNMANNED UNTETHERED VEHICLES (UUV)

    TETHERED VEHICLES, UNTETHERED VEHICLES, RELIABILITY

    IL Sso clew crha f.e 2L. IS&a Poem

    UNLIMITED UNCLASSIFIED

    I2 ftw emm nit~ pm' XL "weUNCLASSIFIED

    Report Docamnw- :-3t

  • REPORT DOCU MENTATION

    PAGE 2

    THE PHASE II TASKING WAS APPROVED BY THE SPONSOR AND SOWs WERE DEVELOPED FOR THETECHNICAL AREAS OF INTEREST.

    THE RESULTS OF THE PHASE I1 SOW DEVELOPMENT ARE PROVIDED AS APPENDICES TO THISREPORT. IT WAS INTENDED THAT THE SOWs DEVELOPED IN PHASE Ii WOULD BE USED 1O

    GENERATE SOLUTIONS IN THE FORM OF RELIABILITY DESIGN SPECIFICATIONS, VIDELT_-ES

    AND DOCUMENTATION FOR THE PROBLEMS.

    IN A FOLLOW-ON EFFORT, THE CONTRACTOR WILL PROVIDE EXPERT TECHNICAL PERSO >'vL,

    MATERIALS, AND FACILITIES NECESSARY TO SUPPORT EXECUTION OF THE INDIVIDUALCONTRACTS FOR THE SOWs.

  • TABLE OF CONTENTS

    I. Executive Summary ................................. 1

    II. Acknowledgements .................................. 3

    III. Introduction ...................................... 4

    IV. Statement of Work (SOW) Development Methodology... 3

    v. Manufacturer List Development Methodology ......... 15

    VI. Conclusions/Recommendations ........................... 13

    Appendix A. Statements of Work (SOW)

    Appendix B. Expert Data Base

    Appendix C. Technical Review Board

    Appendix D. Bibliography

    Appendix E. Distribution

    U4,

    L-, t

    j-I :C H,~ , C

  • I. EXECUTIVE SUMMARY

    A Remotely Operated Vehicle (ROV) reliability study wasinitiated in two phases to determine how ROVs can bedesigned and built to achieve enhanced operationalreliability when operated during extended underwaterdeployment. The contractor was to examine the technologyused in the design and construction of representative ROVswhich are currently state-of-the-art (Phase I) and documentproposed design or construction methodology to effect highreliability (Phase II). This report is the final report ofthe contract, focusing on the Phase II Statement of Work(SOW) development. The Phase I study report was deliveredpreviously.

    The Phase I study results revealed that the process ofdevelopment and procurement of ROVs for Navy use presentlyinvolves modification of off-the-shelf commercial vehicles.Long term reliability is not a design criterion forcommercial vehicles and is certainly lost in the developmentprocess due to cost competition. As a result, commercial-grade vehicles with broad applications are modified forspecific requirements. These vehicles have reliability andother problems as described in detail in the Phase I studyreport.

    Present state-of-the-art ROVs cannot be modified to meet thereliability requirements of extended deployment vehicles.Develcpment of a highly reliable long term deploymentvehicle requires the rigorous use of a thorough developmentprocess. Experts in the field recommend that simultaneouslywith vehicle development, efforts should be initiated upfront to develop technological approaches and design andmanufacturing criteria to address the long term reliabilityproblems identified in the study.

    The results of the Phase I study were compiled and detailedin the Phase I study report. A prioritized listing ofrecommended theoretical and experimental work to improvevehicle reliability was developed from the study results andforwarded in the form of a proposal for Phase II taskingapproval.

    The approved Phase II tasking resulted in the development ofSOWs for each of the technical areas of interest. The SOWsare provided herein as Appendix A. Two lists were alsogenerated, one of manufacturers known to produce qualityunderwater connectors and another of manufacturers known toproduce quality syntactic foam. These lists were providedto the Government under separate cover.

  • This final report, specifically Sections IV and V, describeshow the SOWs and lists were derived, and details theinteraction with the experts during list development. Theresultant SOWs are included as appendices to this report.(The Contract Data Requirements List (CDRL), form DD1423,and Figure (1) to the SOWs, Acoustic Noise Levels, will beprovided by the Government). It was intended that the SOWsdeveloped in Phase II would be executed vid contracts togenerate solutions in the form of reliability design andspecification guidelines for each of the problems.

    2

  • II. ACKNOWLEDGEMENTS

    The contractor would like to acknowledge the assistance ofthe following people in identifying experts in varioustechnical fields:

    Mr. Theodore AustinNUWES, Keyport, WA

    Mr. Dennis HurstHoneywell Inc.

    Dr. Colin SandwithApplied Physics LabUniversity of Washington

    Dr. Robert SpindelDirector, Applied Physics LabUniversity of Washington

    Dr. Robert WernliNOSC, San Diego, CA

    Mr. Jeffrey Wilson,Naval Civil Engineering Laboratory

    A list of the many technical personnel contacted and whoparticipated during the course of this contract are listedin Appendix B.

    3

  • III. INTRODUCTION

    1. Summary

    A Remotely Operated Vehicle (ROV) reliability study wasinitiated in two phases to determine how ROVs can bedesigned and built to achieve enhanced operationalreliability when operated following extended underwaterdeployment. The contractor was to examine the technologyused in the design and construction of representativestate-of-the-art ROVs and document proposed design orconstruction methodology to effect high reliability. Theresults of the contractor's Phase I study effort isdocumented in reference (a).

    The result of the Phase I study was a prioritized listing ofrecommended theoretical and experimental work for Phase IItasking approval.

    The Phase II approved tasking included the preparation ofStatements of Work (SOWs) for each technology area ofinterest to the government. The purpose was to address eachof these technology areas thoroughly and to define theproblems for generation of SOWs. The SOWs would be used todevelop design guidelines, specifications and documentationfor the ROV design engineers. The technology areasrequiring the generation of SOWs were:

    1. Hydraulics2. Seals3. Suspect Manufacturing Processes4. Variable Ballast5. Buoyancy Materials6. Tether Assemblies7. Dry Connectors8. Magnetically Coupled Thrusters

    In addition to the generation of SOWs, two lists, one toidentify Reliable Connector Manufacturers and the other toidentify reliable Syntactic Foam Manufacturers was requestedby the government. These lists were provided under separatecover.

    The SOW development methodology is described in Section IV.The methodology used to generate the manufacturers list isdescribed in Section V.

    2. Program Overview

    2.1 Description of Work

    The program was a two-phased study contract to determinehow Remotely Operated Vehicles (ROVs) can be desianed orbuilt to achieve reliability of 0.98 or better when

    4

  • operated during extended underwater deployment. Thecontractor was to examine the technology used in thedesign and construction of representative ROVs which arecurrently state-of-the-art (e.g. the Perry OffshoreSystems' TRITON or AMETEK's SCORPIO) and documentproposed design or construction methodology to effecthigh system reliability. The ROV system includes thelaunch, recovery and storage system, power and controlcables and the tether storage and management subsystemthat would be required to support the ROV when installedon platforms from which the ROV would be deployed.

    2.2 Program Description

    The contract for the study consisted of two phases: thefirst to review the design, manufacturing processes,maCerials used, sensors, lights, cables, connectors,handling systems and electronic component reliability ofROV systems; and the second, to develop, recommend anddocument specific design and manufacturing methodologiesto use, or to change current practice as necessary toachieve the desired reliability. To satisfactorilycomplete this work, the contractor used consultants whoare experts in the various ROV components and subsystems.The deliverable from the contract was to be acomprehensive technical report detailing technologicalapproaches and design and manufacturing criteria todesign, construct, and operate an ROV system having thedesired reliability.

    2.3 Program Modification

    During the conduct of the Phase I study it becameapparent that development of detailed technologicalapproaches and design and manufacturing criteria todesign, constcuct, and operate an ROV system havinq tnedesired reliability was an inappropriate next step ana anadditional step was required in the development process.The additional effort required definition of the problemsin sufficient detail so SOWs could be generated. TheSOWs could then be awarded as contracts to have thedetailed technical approaches developed, and design andmanufacturing criteria generated. This additional stepwas approved and has required a follow-on Phase III toexecute the SOWs generated in Phase II.

    2.4 Deliverables

    The contractor provided a written report at the end ofPhase I which was accepted and approved by the governmentprior to proceeding to Phase II. This document serves asthe final report required at the conclusion of Phase IIefforts. A program plan was developed for each -rogr~nph&se (delivered separately). Oral and written progress

    5

  • reports were made as necessary during the conduct of thiscontract. A detailed description of the methodology forconduct of Phase I was included in the Study Report,reference (a). The methodology for the conduct of PhaseII and the deliverable SOWs are included in this, theFinal Report.

    3. Reliability Study Discussion

    3.1 The state-of-the-art and maturity of the ROV marketwith regard to the US Navy, has led to the U.S. Navy'suse of commercial grade broad application vehicles thathave been modified for specific requirements. Long termreliability is not a design criterion and is certainlylost in cost competition. Vehicles are reqaired tooperate for hours, not weeks; these ROV can be easilyretrieved and repaired, if necessary. Extensivemaintenance is performed between the short operationalperiods. Present state-of-the-art ROVs cannot bemodified to meet the requirements for reliability :fextended deployment vehicles. Instead, a vehicle willhave to be developed to meet the stringent requirementsfor extended deployments.

    3.2 To develop a highly reliable, long-term deploymentvehicle requires the rigorous use of a thoroughdevelopment process. This process should includerequirements definition, prototype design and developm.entthough full scale engineering development, and theassociated test programs to ensure that the prouct beingdeveloped will meet the system design requirements.

    3.3 The Phase I study identified several reliabilityproblem areas Lhat needed to be addressed. A thoroughassessment of those problems along with identification ofsolutions would ensure that the reliability problemswould be ddequately addressed in any vehicle develop-t-.

    3.4 A synopsis of the reliability problems consideredsignificant for a future long-tetin exposure system showsthat solutions would affect both the design and themanufacturing processes.

    All of these problems must be addressed in order to bringan ROV system to a state of high reliability. In amajority of cases, however, this design for increasedreliability will be at the ex:pense of ease ofmaintenance. In most design changes tc increasereliability, Mean Time Between Failures (MTBF) figuresand those for the Mean Time To Repair (MTTR) are relatedin that an increase in the time between failures willincrease the time required to repair the system.

    6

  • Both simplicity of design and operational requirementsare closely related to reliability. The more complex thesystem becomes and the more varied its requirements, themore unreliable it will become.

    In conclusion, of the reliability problems identified inthe Phase I study, the government chose to pursue thedetailed investigation and development of Statements ofWork for seven of them. The purpose of this report is todetail how the problems were addressed and how theStatements of Work were developed (Section IV). Themethodology for development of the two lists is alsoincluded (Section V). This report provides the vehiclefor forwarding the approved Statements of Work. TheManufacturers lists were provided to the Government underseparate cover.

    -7

  • IV. STATEMENT OF WORK (SOW) DEVELOPMENT METHODOLOGY

    1. Approach

    The following is a description of the process by which theStatements of Work were generated:

    1.1 The individual task problems were defined ascompletely as possible using inputs from expertsidentified during the Phase I study. The expert database list was expanded during Phase II after discussionsAnH meetings with persons identified to us as the expertor experts in the technological area of interest. Usin-gthese experts, the individual task problems were furtherconfirmed as problems for the high reliability Ro'designer. This confirmation process resulted in on!y oneof the original problems being reclassified as a non-problem (dry connector failure from vibration) by theexperts. The decisions were Lupported by the technicalreview board.

    Through a variety of meetings, telephone contacts and on-site visits, the contractor developed specific problemdefinitions as well as specific potential solutions tothe problems. Visits to experts located across thenation were necessary to discuss the problems andpotential solutions for development of the Statements ofWork. Included were meetings with NOSC fr discussionson all eight problem areas, Gianinni Institute fordiscussions on magnetically coupled thruster assemblies,Harbor Branch Foundation for discussions on connectorsand variable ballast systems, University of WashingtonAPL for discussions on all eight problem areas, NCEL fordiscussions on tethers and connectors, Woods HoleOceanographic Institution for discussions on all eightproblem areas, NUWES for discussions on all eight problemareas, Brantner Sea Con, Impulse, D.G. O'Brien,Envirocon, Burton, for discussions on connectorreliability, Rochester Corporation concerning tethers andconnectors, Coors Ceramics for discussions onalternatives to the use of syntactic foam, CumingCorporation, W. R. Grace, and Flotation Technologies fordiscussions on limitations of syntactic foam.

    1.2 The detailed task nroblem3 generated in Section 1.1were used by the contractor in developing the individualSOWs. After internal review, each draft SOW was reviewedby the respective Technology Review Board (TRB)member(s). The TRB consisted of expert(s) considered themost knowledgeable in their field and available. Theirexpertise was used to guide the development of the finalSOWs. It should be noted that significant effort wasmade to ensure that both the experts and the TRB

    81

  • member(s) were thoroughly indoctrinated with regard tothe requirements and objectives of the contract. As aresult, we found our experts and TRB member(s) verysupportive of the SOW development and the Navy's effortto address technology reliability problems up front,prior to vehicle design. We feel this enthusiasm isreflected in the quality of the efforts put forth by theexpe:ts and TRB member(s). The ROV technical experts andTRB members are identified in Appendices B and C,respectively.

    1.3 The developed SOWs were forwarded to the governmentfor internal review and comment. On receipt of thecomments, the necessary changes were incorporated intothe SOWs. The final SOWs are forwarded as Appendix A tothis Final Report. The Contract Data Requirements List(CDRL) form DD1423, and Figure (1) to the SOWs will beprovided by the Government.

    Major comments from government reviewers included theirdesire to include AUVs in the effort and to modify thedesign depth guidelines to include 3,000 feet and 20,000feet.

    1.4 During development of the SOWs, pertinent comments,technical inputs and general information were acquiredfrom the experts which had direct bearing and inputs onhow the SOWs were structured. These comments, technicalinputs and information are considered important and areprovided here as insight into the development of theSOWs.

    1.4.1 Hydraulics Statement of Work

    In developing the Statement of Work to solve chronichydraulic system problems, the approach was reasonablystraightforward. Although the problems are classic andgeneric to many hydraulic systems existing today, theexperts developing the problem definitions focused onhighly specialized aspects of hydraulic systems. Forthis SOW, the technical review board had considerableinput.

    1.4.2 Seals Statement of Work

    As in hydraulics, the seals SOW was reasonablystraightforward; however, the seal problem is verybroad and includes static, rotary, and sliding seals,each of which requires a separate definition/solution.The broad nature of this SOW required a variety ofexpert input in order to accomplish precise problemdefinition.

    9

  • 1.4.3 Suspect Manufacturing Processes Statement ofWork

    The structuring of this SOW was difficult and it soonbecame apparent that the contracting approach beingutilized for execution of the other SOWs wasinappropriate in this effort. The developer of thesuspect manufacturing processes list had to be anuninterested third party able to interface with themanufacturers providing inputs. To accommodate thisapproach, an SOW was generated for implementation byMarine Imaging Systems. The planned approach is asfollows:

    Marine Imaging Systems would contact those majormanufacturers who have provided work vehicles to thegovernment, who have production facilities and who haveexperience with production runs of medium and largesized remotely operated vehicle systems. Thesecontractors would be requested to compile a list of ROVreliability problems they or their users haveexperienced that have resulted from past or presentmanufacturing errors or faulty production design.Participation in the error identification effort wouldbe encouraged by offering manufacturers the results ofthe effort.

    Marine Imaging Systems would compile those lists ofreal and potential errors as supplied by themanufacturers and form a matrix of errors, causes andrecommendations/solutions. The deliverable from MarineImaging Systems would be an outline of manufacturingerrors and production design faults that have causedreliability problems for ROV systems in the past.

    The list would be cross-referenced so that the designerand/or manufacturer of high reliability vehicle systemswill be able to draw from it to help in preventingsimilar problems in future manufacturing processes. Inorder to protect the participating manufacturers whoare providing the information, MIS would organize theinformation not by manufacturer but rather by the majorvehicle categories. The list would also be sanitizedfor the protection of the individual manufacturers.Emphasis would be placed on identifying errors ratherthan those who experience them.

    1.4.4 Variable Ballast Statement of Work

    During Phase I of the study, emphasis had been placedon 1500 psi ROVs for variable ballast systems. DuringPhase II when 3,000 and 20,000 foot systems were to beconsidered it was realized that each of these depthswould require its own unique approach. It was

    10

  • discovered during Phase II that most of the VariableBallast systems in use today for the deeperapplications were designed in the early 1970's and manyof the parts are obsolete and no longer manufactured.This new problem was also taken into consideration indeveloping the Variable Ballast SOW.

    1.4.5 Buoyancy Materials Statement of Work

    During early phases of research on the BuoyancyMaterials SOW there were indications that the problemdescribed in Phase I may have become obsolete, howeverfurther investigations showed that there was really nousable specification for quality syntactic foam forgovernment applications. Further, the specificationsin existence were outdated and, today, higherperforming foams are in use. It was realized thatthere is a need for both design recommendations as wellas specifications for high reliability foams.

    1.4.5.1. Additional Tasking (Functional Alternativesto Syntactic Foam)

    The Syntactic Foam task, to develop a Statement ofWork, requested that MIS present alternative effortsthat are ongoing to design pressure hulls frommaterials that would not require the use of syntactic.Our investigations were only into the unclassifiedactivities of R&D efforts. Although some aspects ofwork underway at Coors Ceramics in Golden, CO werecorporately classified, we were able to judge the stateof the technology from a conceptual standpoint.

    Historically, syntactic foam used for flotation onunderwater structures has exhibited reliabilityproblems over the long term. In an effort to find amore suitable solution to underwater systems buoyancy,a number of avenues have been explored. The mostpromising to date has been the elimination of anyrequirement for buoyancy by designing the structuralcomponents of the underwater system from lightweightmaterials. Classically, materials with a low weight todisplacement ratio (light weight) have had lowstrength, even when designed into structures in such away as to maximize strength (interior or exterior ribstiffening, lamination, etc.). New materials,specifically ceramics and Filament Wound Epoxy (FWE)composites have undergone extensive R&D and testing inan effort to produce workable configurations for largediameter cyl nders strong enough to survive highcompression forces.

    11

  • 1.4.5.1.1 Composites

    Although FWE technology is not immature, most pastapplications for it have been in the aerospace industrywhere high compressive forces on cylinders are nottypically found. One of the first major steps inutilizing reinforced resins in a pressure hull on acommercial submarine was made by a British firm,Slingsby Engineering Ltd., by the construction ofseveral manned submersibles including a 21 ton lockoutboat (LR5), from glass filament wound cylinders. Sincethe main cylinder in manned submersibles is typicallylarge diameter, and the interior is only partiallyfilled with equipment, these systems requiresubstantial ballast loads. The same is not expected tobe true for unmanned vehicles where functionaldiameters will be far less with smaller electronics andequipment densities.

    The major limitation to composite hulls appears to betheir low resistance to abrasion and shock.Delamination of the materials, resulting in significantstructural weakening, has been the major effect ofshock.

    More recent experiments in Filament Wound Epoxy (FWE)cylinders under hydrostatic pressure have shown wallfailure beginning with delamination due to the exposureof cylinder wall ends to hydrostatic pressure as well.Although this problem may be solved with wall-endtreatment or sophisticated "outside-seal" endcapdesigns, the manufacturing process is not asstraightforward as with some other materials.

    Of the two materials now being used for the highstrength component in composite structures (graphiteand glass), FWE using glass fibers appears to bestronger, albeit heavier, in formulation whereapproximately 70% fiber content is used. Althoughgraphite fibers result in more costly manufacturingprocesses and are lighter, they may be preferable overglass in applications where maximum buoyancy isrequired.

    Recent experimentation with hybrid compositesconstructed from both glass and graphite FWE appear tohave very attractive weight to displacement ratios.However, further testing is required to determine thesuitability of these hybrid composites in environmentswhere abrasion and shock loading will be found.

    12

  • 1.4.5.1.2 Ceramics

    For decades, ceramics cylinders constructed fromPyroceramtm, alumina, zirconia and silicon carbide havehistorically been viewed with potential for use aspressure hulls, yielding high strength and a low weightto displacement ratio. However, even more thancomposites, these materials are susceptible to damagefrom shock. There are man, different formulae forceramic materials and ong. ing experimentation mayprovide more shock resistant materials. Although theJapanese have been applying ceramics to underwaterbuoyancy spheres for over 15 years, the actalapplication of these materials as cylinders in themarine environment is relatively immature. Some of thetechnological limitations in ceramics involve controlof tolerances when manufacturing large diametercylinders, although ongoing R&D may provide solutionsto this.

    The major limitation to the ceramic designs forpressure hulls still appears to be shock. In purecompression, ceramic cylinders posses extremely highstrength and even more so in a spherical configuration.However, the materials used to date have a limitedcapacity to withstand shock, failing most often byspalling, chipping or cracking.

    1.4.5.1.3 Overview

    There appears to be, at the present time, an industrycapacity limit to both FWE and ceramic cylinders foruse in large diameters applications. Further thereappears to be technology limitations to both conceptsbut significant funding is urging further technologicaldevelopments at a rapid pace.

    These developments may provide hull structures thatwould eliminate the requirement for syntactic foammodules. Although the American oceanographic industrycommonly uses cylindrical pressure hulls constructedfrom FWE materials, for the near term, it appears thatpressure hulls of the diameter required for medium andlarge size unmanned vehicles will be constructed frommetals such as titanium and aluminum. The weight todisplacement of these materials will require theattachment of low density modules such as syntacticfoam to increase the overall system buoyancy.

    1.4.6 Tether Assemblies 3tatement of Work

    A major factor in developing the SOW to solve chronicproblems in ROV powered tether systems was the apparentdichotomy between the design performance of tethers

    13

  • (and underwater cables) and the actual manufacturedproduct performance in real-world applications. Thisrequired careful examination of historical performanceof a variety of cable types under a variety ofconditions in order to predict problem areas that mayoccur in future high reliability tethers.

    1.4.7 Dry Connectors Statement of Work

    Research into the problem of dry connector failureproved that there is not a problem and those companiesthat had reported these failures described in Ohase I,had simply been using improper components and .gnoredavailable design guidelines. It was recommended thatthis effort be dropped and a SOW was not developed.

    1.4.8 Magnetically Coupled Thrusters Statement ofWork

    In closely defining the problem of limited powerapplicability to magnetically coupled thrusterassemblies, two related and important problems becamevery apparent. These are: (1) the high levelacoustic signature of bearings in water contact and,(2) corrosion problems from exposing sensitivethruster components to the environment. These newproblems may also be solved through the use ofmagnetics and, as a result, were included in the SOWfor magnetically coupled thrusters.

    14

  • V. LIST DEVELOPMENT METHODOLOGY

    1.1 Overview

    In developing the lists of ROV system componentmanufacturers (Underwater Connectors and Syntactic Foam)the approach for each differed greatly due to the natureof the product application. Because there is anextremely limited application for syntactic foam andthere are a limited number of companies that produce theproduct, generating the list of recommended syntacticmanufacturers was a comparatively straightforwardprocess. In contrast, the sheer number of underwaterconnector types available to the design engineer andrelatively large number of connector manufacturers madethe generation of the reliable connector manufacturer amuch more complex process. Also, since far more peoplehave had considerable historical experience withunderwater connectors many more experts had to beconsulted. The analysis of connector manuficturersrequired a lengthy process of assuring that the properpeople were contacted in order to properly analyze theconnectors available.

    1.2 Connector List

    There are approximately ten major American underwaterconnector manufacturers who supply the major portion of a20 million dollar worldwide annual market. Of thesemanufacturers most have a good knowledge of their productperformance in the field under working conditions overtime as a result of feedback from their customers. Inorder to determine what companies provide reliableproducts in service it was necessary to interview manyexperienced users of many different kinds and types ofconnectors. Even the most experienced program managersde-emphasize electrical connector problems, because theconnector component is physically small, relative!1simple in design, and often low cost in comparison to theequipment or vehicle on which it is used. Therefore, itis usually expected to perform well. When it does not,it often jeopardizes entire programs and can result invery expensive losses. As a result, users find it intheir own interest to provide failure data to themanufacturer.

    The Phase II work included interviewing numerous expertsin the field of underwater connectors. These peopleincluded major underwater systems manufacturers,commercial and Government underwater equipment users andGovernment program managers. Each had extensiveexperience with underwater connectors of a variety oftypes and styles.

    15

  • The interviewees were virtually unanimous in theiropinions of the companies who manufactured qualityconnectors. Some experts agreed that there is nofoolproof connector and of the two companies favored forreliability, many experts had qualifying statementsrelative to each.

    In selecting the reliable components produced by the twomanufacturers, we chose to go to the manufacturersthemselves. It was determined that, although they may bebiased, the manufacturer has the most complete knowledgeand data on individual design reliability. Consequently,it was in the governments best interest for themanufacturer to supply this data.

    During interviews and discussions with the twomanufacturers, individual connector and/or connectortypes were identified as being the most reliable. Thelist of reliable connectors was generated specificallywith the assistance of the two manufacturers.

    A description of connector types and typical applicationsaccompanies the reliable connector list which wasdelivered separately.

    1.3 Syntactic Foam Manufacturers List

    There are less than ten manufacturers who haveconsistently produced syntactic foam for the Americancommercial and government market. This market isconsiderably smaller than the connector market and somemanufacturers produce foam from very small facilities, onand off, as demand for small amounts of the productarise.

    In analyzing the producers of this product, we chose toconcentrate on the manufacturers that consistentlyproduced the product and have had a history of doing so.

    Although there are manufactures of quality foam in theU.S. and England, as a result of our Phase II interviews,it appears that there is no manufacturer of syntacticfoam that produces a high performance foam that does notexhibit water pickup, eventual degradation from stressesencountered in deployment, and that is also notformulated from potentially harmful constituents. Thedevelopment of the SOW on syntactic foam was directed atthe definition/design of such a high performance foam(Appendix (A)).

    t6

  • 10 25 91 09:00 %50 759 1595 MAROUEST GROUP 002

    One of the difficuLtie t~nr:vered in defining individualreliability problems with syntactic foam is that many ofthe experts in this field work in the foam manufacturingindustry. It was necessary, therefore, to look toindividual manufacturers for some of the expertiserequired in defining individual problem areas.

    A list of major syntactic foam manufacturers was preparedand provided to the Government under separate cover.

    17

  • VI. CONCLUSIONS/RECOMMENDATIONS

    1. Conclusion

    To provide credibility to the development of the Statementsof Work (SOWs) in Phase II, extensive effort was expended toidentify the experts in each of the technological areas.Their expertise was subsequently applied to define theproblems, define the approaches for solving the problems andto develop the SOWs. The result was the generation of sevendetailed SOWs which are available for execution to addresshigh reliability technological problems prior to thedesign/development of high reliability Remotely OperatedVehicles by the government. The experts identified duringPhase II are available for the next phase of the program tosupport execution of the SOWs. Their participation willincrease the chances of the government receiving a qualityproduct.

    2. Recommendations

    It is proposed that the SOWs developed in Phase II beexecuted to generate solutions in the form of reliabilitydesign specifications, guidelines and documentation to theproblems.

    It is recommended that the experts be utilized to provideknowledgeable personnel to support execution of the SOWcontracts. A detailed proposal describing the recommendedapproach for the use of experts in the execution of the SOWshas been prepared and provided under separate cover.

    18

  • APPENDIX A

    STATEMENTS OF WORK (SOW)

    1. Hydraulic Systems

    2. Magnetically Coupled Thrusters

    3. Suspect Manufacturing Processes

    4. Buoyancy Materials

    5. Sealing Systems

    6. Tether Assemblies

    7. Variable Ballast Systems

  • STATEMENT OF WORK

    FOR

    High Reliability Remotely Operated Vehicle (ROV)

    and Autonomous Underwater Vehicle (AUV)

    Hydraulic Systems

    Prepared By:

    Marine Imaging Systems, Inc.8 Otis Park DriveBourne, MA 02532

    Prepared For:

    Office of Naval Research (ONR)Warfare Technologies Division

    (ONR Code 122)

  • TABLE OF CONTENTS

    Section/Paragraph

    1 BACKGROUND AND INTRODUCTION........................ 1

    2 APPLICABLE DOCUMENTS................................ 22. 1 Other Government Documents......................... 2

    3 SCOPE.................................................2

    4 REQUIREMENTS......................................... 34.1 Critical Design Areas............................. 34.1.1 Hydraulic System Leaking and Flooding Problems .44.1.2 Hydraulic Line Failure Problems.................. 74 .2 Manufacturing...................................... 84.2.1 Components......................................... 94.2.2 Fabrication and Assembly.......................... 94 .3 Reference Documentation........................... 9

    5 DELIVERABLES....................................... 105.1 Program Plan (A002)............................... 105.2 Project Status (AO0l)............................. 115. 3 Final Report (A005)............................... 115.3.1 Problem Documentation (A005)................ ..... 115.3.2 Reference Documentation (A003).................... 135. 3 .3 Manufacturing Errors (A004)....................... 13

  • STATEMENT OF WORK

    1. BACKGROUND AND INTRODUCTION

    Future Navy requirements will involve protracted deploymentsof underwater Remotely Operated Vehicles (ROVs) andAutonomous Untethered Vehicles (AUVs) . To date, theperformance of such vehicles has been heavily dependent onthe quality and quantity of the maintenance and supportavailable during relatively limited deployments. An ROVdesign that is appropriate for industrial (e.g., petroleumindustry) operations, with limited exposure and theexpectation of much maintenance, as a tradeoff againsthigher initial cost, is inappropriate for military missionswith little or no opportunity for upkeep. As a result, thecommon practice of modifying existing ROVs and ROVsubsystems for long term, at-sea storage and/or operationwithout maintenance is not considered to be a long termsolution for extended mission Navy operations.

    The following operational capabilities and reliability goalsneed to be achieved for the Navy to meet its long termdeployment ROV/AUV requirements. The vehicles must bedesigned and built to achieve an operational reliability of98% or better when operating from submarines duringprotracted deployments (3-6 months wet or in a powered-downconfiguration for one to two months followed by severalweeks of subsequent operations) . The ROV/AUV systemoperational capabilities to be considered are as follows:

    1. The operational depth design consideration is a maximumof 3,000 feet. Consideration shall also be given tosystems that have a maximum depth capability of 6,000feet.

    2. TETHERS:

    A. The ROV system shall have a 4,000 ft powered tetherworking from a station keeping platform with a maximumdistance from the platfform of 3,000 feet in anydirection. Station keeping is defined as zero relativevelocity between platform and geodetic or geographicsurroundings.

    B. The AUV shall have no tether.

    3. The ROV or AUV system shall have low self-radiated noise,according to the goals shown in Figure I, and itsauxiliary acoustic components shall not interfere withthe platform sensors. The entire system should minimizeacoustic radiation.

  • 4. The ROV or AUV system's magnetics shall not interferewith the platform or its sensors and vice versa.

    5. The ROV's capacity for a variety of work tasks, includingheavy duty work and high power manipulators, shall alsobe considered.

    6. The ROV's or AUV's maximum nominal speed shall be 5knots.

    All aspects of the system life cycle that may offsetreliability were considered in an initial investigation,including; design, procurement practices, fabrication,inspection, in-service use and maintenance. The reliabilityproblems identified in the investigation report covered theentire development phases of design, manufacturing and in-service life. The in-service life phase, concerned withtraining, maintenance and documentation are not to beconsidered under the tasking of this SOW, but later on aspart of a specific system design. The focus of this SOW ison the application of technology to improve reliability.

    Specifically, this statement of work addresses ROV/AUVhydraulic systems reliability problems and how their designmight be improved to help obtain the long range Navyobjective of achieving a substantial increase in theextended mission reliability of ROVs/AUVs.

    2. APPLICABLE DOCUMENTS

    2.1 Other Government Documents

    The following Government document forms a part of thisspecification to the extent specified herein.

    David Taylor Research Center, Annapolis - Ocean EngineeringHandbooks

    3. SCOPE

    The objective of this SOW is to provide recommendations forspecific solutions to chronic failures in hydraulic systems.This will be presented in the form of deliverables so thatdesigners can use this information in the creation of newvehicles and systems, or in ti-oubleshooting/retro-fittingexisting systems.

    The work will be focused on ways to improve the reliabilityof hydraulic systems, including associated controls,plumbing and fittings. The trend toward quieter vehicles,and therefore quieter and lower power hydraulics, isrecognized as a major future design goal. Quieting a systemworks against reliability in a volume constrained system,and can, with a high reliability ROV/AUV, drive up the size

  • and complexity of the vehicle. Consequently, the contractorshall conduct design trade-offs to select the optimumhydraulics design affording the desired reliability levelwith the least noise.

    Hydraulic failures (unrelated accidents excepted) can comeabout for a wide variety of reasons, but they may be groupedinto two major areas of proximal cause:

    * Those traceable to faulty design* Those resulting from faulty materials or manufacturing

    processes.Those resulting from improper building, assembly ormanufacturing workmanship.

    The SOW is organized around the two areas of design andfabrication with "faulty materials or manufacturingprocesses" included under the latter area. Further, the SOWis structured so as to treat each thoroughly, with thefailure modes as documented to date and described in detailin Section 4. The Design (4.1) and Manufacturing (4.2)subheadings deal with the breakdown of the two majorcategories into areas of specific interest.

    4. REQUIREMEVITS

    The contractors proposal shall identify from an overview howto approach each problem technically, alternativeapproaches, costs and schedules. The approach shall addressthe two major reasons for hydraulic failures as delineatedabove in Section 3 and as follows.

    The contractor shall examine common failure modes ofvehicle hydraulics and recommend design and/or proceduralsolutions to these problems so that they can be implementedat a later date for testing and/or evaluation purposes.These solutions will be in the form of deliverablesdescribed later in this section of the SOW. Thedeliverables shall reflect the current state-of-the-arttechnology, and assume implementation in the next fiveyears.

    4.1 Critical Design Areas

    The overall objective is reliable longer-term deployment ofROVs/AUVs than is possible with current commercial vehicledesigns modified to meet Navy requirements. Severalspecific critical areas have been identified which must beaddressed in order to improve reliability to an acceptablelevel. In dealing witi- specific design recommendations formaximizing system reliability, the contractor must keep inmind that these must be based on the realization thatcompromise is an inevitable part of every design effort.Consequently, the importance of each recommendation,

    3

  • relative to other recommendations, must be indicated.Further, the contractor shall provide reasonable comparisoninformation on the application of less than optimumalternatives and their possible consequences.

    The contractor shall give consideration to the effect ofnoise reduction criteria on system design (see Figure IGoals) and resulting reliability to provide the designerwith adequate information to properly evaluate theconsequences of the trade- offs involved. As an example;(a) the relative merits of low pressure/high volume vs.high pressure/low volume systems, (b) output power vs.quieting, (c) volume occupied vs. quieting, and (c) outputpower to input power ratio vs. quieting shall be carefullydocumented.

    4.1.1 Hydraulic System Leaking and Flooding Problems

    The contractor's critical design review must considerleaking and flooding involving the loss of hydraulicfluid overboard and the ingress of water. The loss offluid overboard is a problem because of the relativelylong time between service/maintenance opportunities.The ingress of water presents corrosion, lubrication,and particle contamination problems.

    Hydraulic fluid loss and water ingress in underwaterhydraulic systems can come about through faulty orimproperly installed line termination, fittings onmotors/pumps/compensators, faulty hydraulic lines orcorroded mechanical components. Another potential leaksite is rotary seals on moving shafts in the hydraulicpropulsion system. These seals commonly experienceexcessive friction and wear which can lead to failureof the seal integrity over a period of time. Mostexisting hydraulic systems can tolerate a limitedamount of fluid loss or contamination because of theuse of sufficient fluid quantities and filters in thesystem. This scenario is not acceptable for a systemundergoing long deployments and this problem requiressolutions to prevent both a loss of fluid and ingressof water into the system.

    4. 1. 1.1 Manifolds

    The use of manifolds machined from solid stock tomount and interconnect control valves and even somepower devices such as linear actuators shall beexamined. The objective is to minimize the quantityof potential leakage sites. This approach canreduce the quantity of potential leak sites (aswell as the space required for lines and fittings)by a significant factor. It is realized that whenmanifolds vice smaller and more convenient

    4

  • connections are employed there may be a serioustrade off between the Mean Time To Repair (MTTR)figures and the Mean Time Between Failure (MTBF)figures. In designing systems to secure highreliability, it may make the vehicle harder torepair at a forward deployment site and require itsreturn to the manufacturer for repair. This processis time consuming, very costly, and adverselyaffects the availability of the vehicle. It isdesirable for these hydraulic systems to beconfigured in a manner that considers the trade-offsbetween repair in the field or at the factory. Thecontractor shall provide recommendations for the useand design of manifolds in the final report. Thecontractor shall also analyze the tradeoffs expectedbetween MTBF and MTTR figures using manifold vicesingle connection interconnects and include thesetradeoffs in the final report (CDRL item #A005).

    4.1.1.2 Welded Lines

    The contractor shall examine the use of weldedpiping assemblies and subassemblies to decrease thenumber of leak sites. Consideration shall be givento the weldability of the specific materialssuitable for use in a high pressure, vibrational,long term salt water immersed application. It isacknowledged that the use of welded lines toincrease system reliability carries the sameadvantage and disadvantage in terms of MTBF versusMTTR figures as the use of manifolds (section4.1.1.1.). Considering that maintenance and repairis desirable at a forward deployment site in orderto increase the systems' availability, the trade-offs between the use of welded lines and the use ofother line fittings shall be evaluated. Thecontractor shall provide recommendations for and/oragainst the use of welded lines and suitablematerials in the final report. The contractor shallalso provide the analysis and tradeoffs in MTBF andMTTR figures when using welded lines vice linefittings in the final report (CDRL item #A005).

    4. 1. 1. 3 Threaded Connections

    The need for some threaded connectors is recognizedand the relative merits of the various typesavailable shall be investigated. Since many systemcomponents are available with a limited number ofinterconnection fitting choices, evaluation of thesechoices shall be made to provide analysis of theirsuitability. For example, it may be shown that asingle pipe fitting decreases system reliability byan amount equivalent to using 10 "0" seal fittings

    5

  • but that seal welding the pipe fitting results in ajoint equivalent to socket welding. The contractorshall compare and report on the suitability of theseconnections in the final report (CDRL item #A005).

    Methods for correcting the deficiencies in existingthreaded joint designs shall be considered in thehope that the specific low maintenance applicationwill allow improvements. As an example, it mayprove practical to utilize tack welding to overcomethe tendency of a threaded connection to loosen in ahigh vibration environment. The contractor shallprovide recommendations for improved design ofthreaded connections in the final report (CDRL item#A005).

    The choice of acceptable materials for threadedconnections shall be carefully evaluated.Particular attention shall be paid to problems ofcrevice corrosion and stress corrosion cracking in asalt water environment. Again, the low maintenanceapplication may allow use of novel solutions such asjoint encapsulization in a suitable conformalcoating. The contractor shall evaluate andrecommend acceptable materials for threadedconnections in the final report (CRDL 4tem #A005).

    4.1.1.4 Pressure Loaded Compensator Connection Seals

    Typically a hydraulic system that is designed forunderwater operation is equipped with a pressurecompensator that maintains hydraulic system pressureat or slightly above the ambient water pressure.When the hydraulic fluid pressure is slightly abovewater pressure, if a leak does occur, oil will leakout. This is usually the preferred situation tominimize the possibility of system degradation dueto corrosion. Examination shall be made of optimumcompensator connection points and pressures. Bothactive and passive methods for providingcompensation pressure shall be evaluated. Theexamination results and recommendations shall bepresented in the final report (CDRL item #A005)

    4.1.1.5 High Friction Seals

    At rotary and sliding seals special seal methodssuch as advanced lip or O-ring seal, redundant seal,or hermetic boundary seals shall be examined. Thecontractor shall examine the long term effect ofboth oil and water on these seals. Further, thecontractor shall specify or design and qualify thesehigh reliability sealing methods as a potentialsolution to leaking and flooding. The contractor

    6

  • shall provide these specifications, designs and/orqualifications in the final report (CDRL item#A005). The contractor shall quantify seal leakagerates to expect after 1000 operational hours andassociated passive exposure to saltwater and/or oil.

    4.1.1.6 Other Potential Leak/Flood Problems

    There are many different hydraulic component designsnow in use on Remotely Operated Vehicles. Each ofthese systems may have unique problems with respectto the loss of fluid or ingress of water. Thecontractor shall detail any other problems ofconcern to a design engineer of which he may beaware and provide potential solutions for theseproblems in the final report (CDRL item #A005).

    4.1.2 Hydraulic Line Failure Problems

    Line failure can be caused by several system-design oroperational problems. The major causes of line failurefollowing acceptance testing are; corrosion, abuse, andfatigue resulting from pressure and large spikes orpulsations. Failure modes are normally bursting orleakage but other, less common, failure modes exist.

    Any hydraulic line that carries fluid at or nearambient pressure is susceptible to possible collapse.The line will collapse if the internal pressure issufficiently lower than the external pressure and linewalls are of inadequate strength. Such a line is inunstable equilibrium. If constant flow is maintained,once collapse starts it will tend to quickly proceed tocomplete collapse. Lower internal pressure is due totwo factors; low hydrostatic pressure at the exit endof the line, and fluid flow velocity (which reduceshydrostatic pressure at the line wall) within the line.Bends, external loads or rapid pressure changes due topulsations can aggravate the situation. Collapse in apump suction line can also occur if the systemcompensator bottoms (due to a leak somewhere in thesystem) and the pump continues to deliver fluid. Sincehose generally is weaker than tubing or pipe, it is themore likely system element to fail by collapsing.

    4.1.2.1 Contamination

    Despite a competent manufacturing process,maximizing reliability will involve both particleand water removal. The contractor shall considerthe various methods for accomplishing this and makerecommendations; specifically the type, fineness,location, quantity, size, leakage potential and failsafe aspects of available filtering components shall

    7

  • be addressed. The contractor shall also providerecommendations on cleanliness levels and associatedprocedures. The contractor shall provide theserecommendations in the final report (CDRL item#A005).

    4.1.2.2 Hydraulic Line Noise

    The contractor shall review those areas of existinghydraulic system design practices, Navy andcommercial sound silencing techniques, and the useof noise reduction components (i.e. flex hoses andsound dampeners) with the goal of achieving thedesired reliability level and reduced acousticsradiation. The impact of these designs/componentson reliability shall be examined and specificrecommendations made. The contractor shall providethese recommendations in the final report (CDRL item#A005).

    4.1.2.3 Working Fluids

    Trar-e-offs between various working fluids in thesystem shall be considered for ROV/AUV deploymentswith particular attention to long term wet storageof the system and extended power down periods.Consideration shall also be given to whetherperiodic start-up/exercise of hydraulic systems isnecessary or desirable. The contractor shallprovide these trade-offs and make recommendations inthe final report (CDRL item #A005).

    4.1.2.4 Other Potential Line Failure Problems

    Depending on the type and design of the hydrauliclines in any given system, there may be uniqueproblems with line failure not covered in thissection. The contractor shall detail any otherproblems of concern to a design engineer andpotential solutions of which he may be aware. Thecontractor shall provide a description anddiscussion of these problems and potentialsolutions in the final report (CDRL item #A005).

    4.2 Manufacturing

    Even with reliable, quality designs for all parts of avehicle, system errors in manufacturing involving theincoming materials or components from vendors, fabricationof materials in house and the assembly of these can cause areduction in the overall system reliability. These errorscan be product-wide and effect virtually all units in aproduction run and result in multiple in-service failuresbefore detection.

    8

  • 4.2.1 Components

    Incoming components for the production of vehiclesystems are most often either tested by themanufacturer or certified as tested by the vendor.Even if the components are certified by the vendor theycan still be faulty and cause unpredictable failures inservice. In some vehicle systems, manufacturers willutilize marginally reliable components due to eithercost competition or component availability.

    4.2.1.1 Component Failure

    The contractor shall review the available componentsused in the manufacturing of ROV/AUV systems withregard to their reliability history. The contractorshall consider whether the formulation of a QualityParts List (QPL) for ROV/AUV systems will improvetheir reliability and make his recommendation in thefinal report (CDRL item #A005).

    4.2.2 Fabrication and Assembly

    Errors in fabrication and assembly which may be missedby even a good quality assurance program, may weakenthe product and create later in- service failures.Identification and documentation of these known errorscan contribute to their elimination.

    4. 2. 2. 1 Manufacturing Errors

    During the contract it is expected that thecontractor shall develop a list of commonmanufacturing errors found to cause various types ofhydraulic failures. This list will be valuable inwarning the vehicle designer or manufacturer oftheir existence. The contractor shall make thislist available as an attachment to the final report.The list of errors shall include explanations,desirable alternative solutions, and recommendations(CDRL item #A004).

    4.3 Reference Documentation

    DTRC (Annapolis) has published a series of Ocean EngineeringHandbooks on tcpics ranging from electric underwater motorsto hydraulic systems. These handbooks provide the designerwith examples, design data, standards and other informationof great practical value during the design process. Thecontractor shall draw on these and other sources ofinfuimaLion (z- described elsewhere in this SOW), and on hisown extensive experience in the design and implementation ofunderwater hydraulic systems of all types, and produce a

    9

  • compendium of specific guidelines on how to design toprevent problems (historical and expected) which plague ROVhydraulics reliability. This compendium shall be presentedas an attachment (CDRL item #A003) to the final report.

    The contractor shall make a thorough survey of applicablemilitary standards, specifications and handbooks. Thecontractor shall compile all such documents, cross-referenced and explained so that the designer will have asingle, concise source for selection of applicablecontrolling documents to reference during the preparation ofmaterial, process, or product specificaticns. Thecontractor shall provide this compilation as an attachment(CDRL item #A003) to the final report.

    5. DELIVERABLES

    Designer Guidelines for the technical aspects of thehydraulic system which contribute to failures shall be aprime product (CDRL item #AO05). The contractor shallproduce a compendium of specific design guidelines forpreventing problems which plague ROV hydraulics systems(CDRL item #A003). The contractor shall also provide a listof common manufacturing errors found to cause hydraulicfailures (CDRL item A004). Other deliverables required area program plan (CDRL item #AO02), status reports (CDRL item#AO01) and a final report (CDRL item #AO05).

    The deliverables on this project shall be in contractorformat and in accordance with the attached Contract DataRequirements List (CDRL), Form DD1423. The details of therequired deliverables are as follows:

    5.1 Program Plan (A002)

    The contractor shall develop a program plan in accordancewith CDRL #A002 identifying: how to approach each problemtechnically (including breakpoints), alternative approaches,and a schedule for each required deliverable in section 4 ofthe SOW. The plan shall elaborate on the contractorsproposed technical approach to the SOW and detail how thecontractor will perform each required item within theallocated time and cost. A draft program plan shall bedelivered 30 days after contract award, and is subject toGovernment approval. A final version of the program plan,with Government comments incorporated, shall be required 15days after the contractors receipt of the Governmentscomments.

    10

  • 5.2 Project Status (AO01)

    The contractor shall provide project status in accordancewith CDRL #AO01 by the fifteenth of each month for theprevious calendar month.

    5.3 Final Report (A005)

    A draft final report prepared in accordance with CDRL #A005,describing all research results and conclusions, shall besubmitted 60 days prior to completion of the contract forreview and comment.

    A final report updating the draft report, as required by thereview comments, shall be submitted 30 days after thecontractors receipt of the Governments comments on the draftreport.

    Specific deliverables to be included in the final report arethe following:

    5.3.1 Problem Documentation (A005)

    Section 4 requires the contractor to provideevaluations, designs, specifications, comparisons,trade-offs, descriptions, discussions and/orrecommendations for each specific problem and toinclude the results as separate, identifiable items inthe final report. The results shall be prepared inaccordance with CDRL #A005 for the ROV/AUV hydraulicscomponents, subsystems, supporting/auxiliary equipmentor processes as directed in items 4.1 through 4.2inclusive, less item 4.2.2.1 Manufacturing Errors.The specific items to be reported are:

    (4.1.1.1) Manifolds

    Recommendations for the use and design of manifolds.Provide an analysis of trade offs between MTBF andMTTR figures using manifolds vice singularinterconnections.

    (4.1.1.2) Welded Lines

    Recommendations for the use of welded lines andsuitable materials. Provide an analysis and thetradeoffs in MTBF and MTTR figures when using weldedlines vice line fittings.

    11

  • (4.1.1.3) Threaded Connections

    Provide comparisons and applicability of threadedconnections, and recommendations for improveddesign of threaded connections. Provide anevaluation and recommendations of acceptablematerials for threaded connections.

    (4.1.1.4) Pressure Loaded Compensator Connection Seals

    Provide recommendations of optimum compensatorconnection points and pressures (active and passive)for seals.

    (4.1.1.5) High Friction Seals

    Provide specifications, designs and/orqualifications for sealing methods. Provide aquantification of seal leakage rates expected after1,000 hours of operation with high friction seals.

    (4.1.1.6) Other Potential Leak/Flood Problems

    Provide a description, discussion and potentialsolution for each problem identified.

    (4.1.2.1) Contamination

    Recommendations for removal of particle and watercontamination during the manufacturing process andrecommendations on cleanliness levels and associatedprocedures.

    (4.1.2.2) Hydraulic Line Noise

    Recommendations for the use of designs/components onnoise reduction and reliability.

    (4.1.2.3) Working Fluids

    Provide trade-offs between various working fluidsand make recommendations. Include recommendationson the desirability/necessity of periodic start-up/exercise of hydraulic systems.

    (4.1.2.4) Other Potential Line Failure Problems

    Provide a description, discussion and potentialsolution for each problem identified.

    12

  • (4.2.1.1) Components

    Provide an assessment and recommendations of aQuality Parts List (QPL, program for ROV/AUVsystems.

    5.3.2 Reference Documentation (A003)

    The contractor shall provide a compendium of specificguidelines on how to design to prevent problems whichplague ROV/AUV hydraulics reliability.

    The contractor shall make a thorough survey ofapplicable military standards, specifications andhandbooks. He shall compile all such documents,cross-referenced and explained so that the designerwill have a single, concise source for selection ofapplicable controlling documents to reference duringthe preparation of material, process, or productspecifications. (Item 4.3 Reference Documentation.)

    5.3.3 Manufacturing Errors (A004)

    The contractor shall provide a list of common ROV/AUVhydraulics manufacturing errors including desirablealternative solutions and explanations. (Item 4.2.2.1Manufacturing Errors).

    13

  • STATEMENT OF WORK

    FOR

    High Reliability Remotely Operated Vehicle (ROV)

    and Autonomous Underwater Vehicle (AUV)

    Magnetically Coupled Thrusters

    Prepared By:

    Marine Imaging Systems, Inc.8 Otis Park DriveBourne,MA 02 5

    Prepared For:

    Office of Naval Research (ONR)Warfare Technologies Division

    (ONR Code 122)

  • TABLE OF CONTENTS

    Section/Parag~raph

    1 BACKGROUND AND INTRODUCTION........................ 1

    2 APPLICABLE DOCUMENTS................................ 32.1 Other Government Documents........................ 3

    3 SCOPE................................................. 3

    4 REQUIREMENTS....................................... 34.1 Critical Design Areas............................

    5 DELIVERABLE........................5.1 Program Plan (AOO1)............................... 65.2 Status Report (A002).............................. 65.3 Final Report (A003)............................... 65.4 Prototyping Plan (A004)........................... 8

  • STATEMENT OF WORK

    1. BACKGROUND AND INTRODUCTION

    Future Navy requirements will involve protracted deploymentsof underwater Remotely Operated Vehicles (ROVs) andAutonomous Underwater Vehicles (AUVs )the performance ofsuch vehicles has been heavily dependent on the quality andquantity of the maintenance and support available duringrelatively limited deployments. An ROV design that isappropriate for industrial (e.g., petroleum industry)op-rations, with limited exposure and the expectation ofmuch maintenance, as a tradeoff against higher initialcost, is inappropriate for military missions with little orno opportunity for upkeep. As a result, the common practiceof modifying existing ROVs and ROV subsystems for use inmilitary service is undesirable and is not considered to bea long term solution for extended mission Navy operations.

    The following operational capabilities and reliability goalsneed to be achieved for the Navy to meet its long termdeployment ROV/AUV requirements. The vehicles must bedesigned and built to achieve an operational reliability of98% or better when operating during protracted deployments(3-6 months wet or in a powered-down configuration for oneor two months followed by several weeks of subsequentoperations). The ROV system operational capabilities to beconsidered are as follows:

    1. The operational design depth consideration are maximums

    of 6,000 feet and 20,000 feet.

    2. TETHERS:

    A. The ROV system shall have a 4,000 ft powered tetherworking from a station keeping platform with amaximum distance from the platform of 3,000 feet inany direction. Station keeping is defined as zerorelative velocity between platform ana geodetic orgeographic surroundings.

    B. The AUV shall have no tether.

    3. The ROV or AUV system's shall have low self-radiatednoise, according to the goals shown in Figure I, andits auxiliary acoustic components shall not interferewith the platform sensors. The entire system shouldminimize acoustic radiation.

    4. The ROV or AUV system's magnetics shall not interferewith the platform or its sensors and vice versa.

  • 5. The ROY's capacity for a variety of work tasks,including heavy duty work and high power manipulators,shall also be considered.

    6. The ROV's or AUV's maximum nominal speed shall be 5knots.

    All aspects of the system life cycle that may offsetreliability were considered in an initial investigation,including; design, procurement practices, fabrication,inspection, in-service use and maintenance. The reliabilityproblems identified in the investigation report covered theentire development phases of design, manufacturing and in-service life. The in-service life phase, concerned withtraining, maintenance and documentation are not to beconsidered under the tasking of this SOW, but later on aspart of a specific system design. The focus of this SOW ison the application of technology to improve reliability.

    -pecifically, this statement of work addresses ROV/AUVmagnetically coupled thruster assemblies and how to improvetheir power and reliability without undue increase in sizeor complexity. The objective is to improve the design ofmagnetically coupled thrusters to help achieve a substantialincrease in the extended mission reliability of NavyROVs/AUVs.

    In current state-of-the-art ROV systems there are a numberof different propulsion system designs. One of the morereliable designs utilizes an air backed electric motor.Although the average life of this type of thruster design iscomparatively long, one of the components of this assemblywith the shortest life cycle, is a rotating shaft seal wherethe propeller shaft penetrates the pressure housingcontaining the motor. In many designs this seal, althoughreliable in the short term, demonstrates extremely high wearrates and requires frequent maintenance.

    One type of thruster design implemented on a number of ROVseliminates these shaft seals altogether through the use ofmagnetic field- which transfer rotational power without theuse of sealed, pressure-housing-penetrating shafts. Byeliminating shaft sEals altogether the reliability of theelectric thruster has been greatly improved allowing longterm deployments with little or no maintenance to thethruster assemblies.

  • 2. APPLICABLE DOCUMENTS

    2.1 Other Government Documents

    The following Government document forms a part of thisspecification to the extent specified herein.

    David Taylor Research Center, Annapolis - Ocean EngineeringHandbooks

    3. SCOPE

    The objective of this SOW is to assess the feasibility ofincreasing power levels that can be applied to small,magnetically coupled thruster assemblies and to providerecommendations for specific solutions to increasing theperformance of magnetically coupled thruster assemblies.These will be presented in the form of deliverables so thatdesigners can use this information in the creation ofprototypes for testing and evaluation of the designsolutions.

    The work will be focused on ways to improve the design ofthruster assemblies utilizing magnetic fields to transferpower from an electric motor to a rotating propulsion shaft.The work will also focus on improving the design ofassociated bearings and other parts that may be exposed tothe underwater environment. The trend toward quietervehicles, and therefore quieter propulsion shaft bearings,is recognized as a major future design goal.

    Several problems exist with current designs of magneticallycoupled thrusters. The limitations of these thrusterassemblies fall into 3 categories:

    " Torque limitations within size restrictions.

    " Rotational Speed limitations

    " Abbreviated life of propeller shaft support bearings

    This statement of work is designed around these limitations

    and shall address these problem areas.

    4. REQUIREMENTS

    The contractor's proposal shall identify from an overviewhow to approach each problem technically, alternativeapproaches, additional problems, costs and schedules, andrecommendations for prototyping.

    The contractor shall examine existing designs ofmagnetically coupled thruster assemblies and recommenddesign and/or procedural solutions to these problems so that

    3

  • they can be implemented at a later date for testing and/orevaluation purposes. These solutions will be in the formof deliverables described later in this section of the SOW.The deliverables shall reflect the current state-of-the-arttechnology, and assume implementation within the next fiveto seven years.

    4.1 Critical DesiQn Areas

    The overall objective is reliable longer-term deployment ofROVs/AUVs than is possible with current vehicle designs.Several specific critical areas have been identified whichmust be addressed in order to improve performance to anacceptable level. In dealing with specific designrecommendations for maximizing system performance, thecontractor must keep in mind that these must be based on therealization that compromise is an inevitable part of everydesign effort. Therefore, an indication of the relativeimportance of the recommendations must be provided as wellas reasonable information on the application (and possibleconsequences) of less than optimum alternatives.

    Consideration shall be given to the effect of noisereduction criteria on system design and resultingreliability to provide the designer with adequateinformation to properly evaluate the consequences of thetrade-offs involved.

    4.1.1 Torque vs Size, Weight and Fragility

    The magnetically coupled thruster assemblies in usetoday are fairly large, particularly where higher thannormal torque forces are required. In particular, thematerials used in the past, require inordinately longcoupling housings in order to deliver high levels oftorque to the shaft. New materials may be available atpresent that will allow the use of shorter, morecompact coupling assemblies. These potentialimprovements may allow shorter thrusters overall whiledelivering greater torque than has been possible in thepast.

    It is known that there are further limitations to thematerials used in the past for magnetically coupledthrusters. Sumarium cobalt is a fragile material;Gaudolinium is somewhat stronger magnetically; somerare earth materials are not resistant to hightemperatures.

    The contractor shall investigate and recommend in thefinal report (CDRL item #A003), reliable materials thatwill increase the torque performance of existingmagnetically coupled thruster designs.

    4

  • 4.1.2 Speed

    There are further limitations to the performance ofmagnetically coupled thruster assemblies in terms ofrotational shaft speed. Historically, in order tomake housings for magnetically coupled thrusters usedin deep water (greater than 1000 feet) strong andpressure proof, the materials for these housing aretypically metallic and have been chosen for their highresistivity.

    In using metals (or other conducting materials),designers have found that magnetic inductance from therotating couplings induces eddy currents in the housingmaterials resulting in heat buildup. Most designs ofthis type also have a tangential speed limitation ofapproximately 5 feet per second even when usingrelatively high resistivity metallic materials such ashastelloy.

    The contractor shall evaluate and recommend in thefinal report (CDRL item #A003), new housing materialsthat will substantially improve, or eliminate,rotational speed limitations and inductance heatbuildup in magnetically coupled thruster assemblies.

    4.1.3 BearinQs in Sea Water

    Another drawback to the use of magnetically coupledthruster assemblies is the exposure of bearingassemblies to the environment. This creates anundesirable corrosion problem in the bearing assemblieswhich necessitates undesirable frequencies ofmaintenance. An added performance problem for manyapplications is the added acoustic output of thesebearing assemblies immersed directly in seawater.

    A design that utilizes magnetic bearings may eliminatethe requirements for bearings exposed to sea water andstill allow the shaft to be exposed to seawaterwithout corrosion or acoustic problems.

    The contractor shall provide design recommendations inthe final report (CDRL #A003), for magnetic bearingsfor use on the secondary coupling component inmagnetically coupled thruster assemblies.

    4.1.4 Other Potential Design Problems

    There may be other potential problems encountered inhigh performance magnetically coupled thruster design.The contractor shall detail any other problems ofconcern and provide potential solutions for theseproblems in the final report (CDRL item #A003).

  • 4.1.5 Prototypinq Plan

    If the results of the solutions to the problemsidentified above (and by the contractor) are favorable,and an overall assessment of the feasibility ofincreasing power levels that can be applied to small,magnetically coupled thruster assemblies is promising,prototyping of the design efforts will likely bepursued. The contractor shall provide a plan forprototyping of the designs developed under this phase(including cost and schedule). This effort may beperformed in the second phase of this SOW as an option.The prototyping plan shall be submitted separately fromthe final report as (CDRL item #A004).

    5.0 DELIVERABLES

    The deliverables on this project shall be in contractorformat and in accordance with the attached Contract DataRequirements List (CDRL), Form DD1423. The details of therequired deliverables are as follows:

    5.1 Program Plan (AO01)

    The contractor shall develop a program plan in accordancewith CDRL #A001 identifying how to approach each problemtechnically (including breakpoints), alternative approaches,and a schedule for each required deliverable in Section 4 ofthis SOW. The plan shall elaborate on the contractor'sproposed technical approach to the SOW and detail how thecontractor will perform each required item within theallocated time and cost. A draft program plan shall bedelivered 30 days after contract award, and is subject toGovernment approval. A final version of the program plan,with Government comments incorporated, shall be required 15days after the contractor's receipt of the Government'scomments.

    5.2 Status Reports (A002)

    The contractor shall provide project status in accordancewith CDRL item #A002 by the fifteenth of each month for theprevious calendar month.

    5.3 Final Report (A003)

    A draft final report prepared in accordance with CDRL item#A003, describing all research results and conclusions,shall be submitted 60 days prior to completion of thecontract for review and comment.

    6

  • A final report updating the draft report, as required by thereview comments, shall be submitted 30 days after thecontractor's receipt of the Government's comments on thedraft report.

    Specific deliverables to be included in the final report are

    the following:

    5.3.1 Problem Documentation

    Section 4 requires the contractor to provideevaluations, specifications, design guidelines,comparisons, descriptions and/or recommendations foreach specific problem and to include the results asseparate, identifiable items in the final report. Theresults shall be prepared in accordance with CDRL item#A003 for the ROV/AUV Magnetic Coupled Thruster taskingas directed in items 4.1.1 through 4.1.4 inclusive.The specific items to be reported are:

    (4.1.1) Torque vs. Size, Weight and Fragility

    The contractor shall investigate and recommendreliable materials that will increase the torqueperformance of existing magnetically coupledthruster designs.

    (4.1.2) Speed and Temperature

    The contractor shall evaluate and recommend newhousing materials that will improve on, or eliminaterotational speed limitations and heat buildup in thehousings of magnetically coupled thrusterassemblies.

    (4.1.3) Bearings in Sea Water

    The contractor shall provide design recommendationsfor magnetic bearings for use on the secondarycoupling component in magnetically coupled thrusterassemblies.

    (4.1.4) Other Design Problems

    The contractor shall detail and provide detailedpotential solutions for these problems in the finalreport.

  • 5.4 Prototyping Plan (A004)

    The contractor shall provide a draft plan for prototypingthe designs developed in this phase of the SOW. The planqhall be ,-irt to government approval. A final versionwill be required 15 days after receipt of governmentcomments.

    8

  • STATEMENT OF WORK

    FOR

    High Reliability Remotely Operated Vehicle (ROV)

    Suspect Manufacturing Processes

    Prepared By:

    Marine Imaging Systems, Inc.8 Otis Park DriveBourne, MA 02532

    Prepared For:

    Office of Naval Research (ONR)Warfare Technologies Division

    (ONR Code 122)

  • TABLE OF CONTENTS

    Sect ion/Paragraph

    1 BACKGROUND AND INTRODUCTION........................ 1

    2 SCOPE ............................................. 1

    3 REQUIREMENTS...............................23.1 Critical Manufacturing Problem A reas.........23.1.1 Problems with Working Systems..................... 23.1.2 Vehicles of Recent Manufacture................... 23.1.3 Vehicles Presently in Production................. 2

    4 DELIVERABLES......................34.1 Final Report (AOl)............................... 34.1.1 Problems with Working Systems..................... 44.1.2 Vehicles of Recent Mai~.facture................... 44.1.3 Vehicles Presently in Production................. 4

  • STATEMENT OF WORK

    1. BACKGROUND AND INTRODUCTION

    In the future the U.S. Navy shall require the use of ROVsystems for prolonged deployments. Toward this goal thegovernment would like to compile a comprehensive list ofmanufacturing errors encountered in past ROV manufacturingoperations which may have affected the reliability of theproduct. This comprehensive list shall be provided to ROVmanufacturers to aid in production of more reliable ROVsystems.

    Every manufacturer of ROV systems and ancillary equipmenthas experienced manufacturing errors and production designproblems which have adversely affected the reliability ofthe final product. These errors range over a wide spectrumof manufacturing processes from failure to reinspectcertified incoming subassemblies and components toinadvertently exposing certain materials to a solvent thathad detxiaiental effect on the material months later.Knowledge of all of these errors can assist a manufacturerin providing a more reliable product in the future.

    The most knowledgeable and capable contractors to dssemblecomprehensive list of these problems are the manufacturers.It is anticipated that manufacturers have records a. iknowledge of a variety of manufacturing problems andproduction design errors that have been eliminated forimprovement of product reliability.

    2. SCOPE

    The objective of this contract is to identify problems thathave caused errors in the manufacturing of ROV systems.These problems shall be identified, categorized andpresented in the form of non-attributable deliverables forthe use in the creation of new vehicles and systems, or introubleshooting/retrofitting existing systems. The effortshall be focused on identifying the manufacturing errorsthat have occurred in ROV systems even with adequate QA-QCprocesses.

    3. REQUIREMENTS

    The contractor shall examine and identify from an overviewall ROV manufacturing problems that have been observed bythe manufacturers and their subcontractors. Included inthis examination shall be alternative approaches, andexpected solutions devised to correct the problems. Thecontractor shall categorize the manufacturing errors andrecommend procedural solutions to these problems so thatthey can be avoided in the manufacturing of future high

    I

  • reliability ROV systems. These recommendations shall be inthe form of deliverables to this contract. The deliverablesshall reflect the current state-of-the-art technology, andassume implementation in the next five years.

    i. Critical Manufacturing Problem Areas

    In dealing with specific manufacturing recommendations formaximizing system reliability, the contractor must keep inmind that these must be based on the understanding thateliminating the large majority of these problems does notnecessarily require major restructuring of the manufacturingprocess. It is expected that recognition of many of theproblems shall be sufficient for the manufacturer to avoidthem.

    3.1.1 Problems with Workinq Systems

    ROV systems produced in the past have experiencedreliability problems resulting from production designand manufacturing problems. Many of these problemswere identified by the users and in many cases the usercontacted the manufacturer with full descriptions ofthe problem. The contractor shall outline theseproblems, their cause as it relates to manufacturingand production design and their solutions. Thecontractor shall identify and categorize any suchproblems and provide recommendations/solutions for themin the final report.

    3.1.2 Vehicles of Recent Manufacture

    There are a variety of ROV systems that have beenrecently (within three years) produced which have alimited time in the field. These would include systemsthat, although not yet accepted by the customer, arestill undergoing trials in the field at the presenttime. Many of the major ROV manufacturers haveproducts in this stage of production. Many of thesesystems have experienced faults that may be a result ofproduction design problems and/or manufacturing errors.As in item 3.1.1 above, these failures may be detailedin reports on operations and/or communications witheither the manufacturer or technical support group forthe system. The contractor shall identify andcategorize those reliability problems and providerecommendations/solutions in the final report.

    3.1.3 Vehicles Presently in Production

    ROV systems that are in production at the present timealso demonstrate reliability problems that are a resultof faulty production design or other manufacturingproblems. Most of the manufacturing errors that occur

  • with vehicles currently in production become knownthrough quality testing procedures for the finalsystem. Testing procedures that include vibration andshock tests, environmental tests, and pressure testsoften bring manufacturing errors to light before thesystem experiences field trials. The contractor shallidentify and categorize any manufacturing errors thathave been identified for ROV systems still in theproduction process. Further, the contractor shallprovide these categorizations and recommendationsand/or potential solutions in the final report.

    4. DELIVERABLES

    The deliverable for this project shall be in the contractorformat and in accordance with the attached Contract DataRequirements List (CDRL), form DD 1423. Details for therequired deliverable follow:

    The deliverable for this contract shall include lists of allthe ROV reliability problems, of which the contractor isaware, arising from problems in the manufacturing and/orproduction design process. Recommendations/solutions tothese problems shall also be detailed for each problem area.These lists should be categorized bymanufacturing/production processes within the three majorgroupings of vehicle field history.

    The deliverable for this contract shall be in the form of afinal report, CDRL Item # A001, including the above listsand categories. This report will be compiled with the finalreports from the other manufacturing contractors for thegovernment by Marine Imaging Systems. During thiscompilation the identification of contractors contributingto the report and the identification of specific ROV systemsshall be eliminated thus making the individual problemsoutlined generic and anonymous in the final compilation.

    This compilation shall be made available to themanufacturing contributors to this effort. This willprovide to the contributors listings of major manufacturingerrors, production design problems andrecommendations/solutions to these problems, so that theymay avoid these problems in future manufacturing efforts.

    4.1 Final Report (AO01)

    The final report, CDRL Item # A001, shall outline ROVreliability problems which stem from manufacturing errors.These errors/problems shall be categorized by vehicle fieldhistory as described in Sections 3.1.1 through 3.1.3 of thisStatement of Work. The problems shall be further sub-categorized by production processes within each majorcategory. For each problem area (or each individual problem

    3

  • if appropriate) recommendations/solutions to the problem asthey relate to manufacturing or production design shall beoutlined.

    A draft final report prepared in contractor format,describing all results and conclusions, shall be submitted60 days prior to completion of the contract for review andcomment. A final report updating the draft report, asrequired by the review comments, shall be submitted 30 daysafter the contractors receipt of the review comments on thedraft report.Specific deliverables to be included in the final report

    are:

    4.1.1(3.1.1) rroblems with Working Systems

    The contractor shall identify and categorize anymanufacturing related failures to ROV systems whichhave a significant field history and providerecommendations/solutions for them in the final report.

    4.1.2(3.1.2) Vehicles of Recent Manufacture

    The contractor shall identify and c