- REMOTE WORK EXPERIENCE

Transcription

1 THE WORK SYSTEMS PACKAGE - REMOTE WORK EXPERIENCE Robert L. Wernli NAVAL OCEAN SYSTEMS CENTER SRN DIEGO, CALIFORNIA Abstrct The Work Systems Pckge (WSP), 20,000 foot mnipultive work system, hs been undergoing opertionl testiy t-send in the lbortory since It hs been tested on the Nvy's unmnned tethered vehicles, Cble Controlled Ltnderwter Recovery Vehicle (CURV III), Remote Unnnned Work System (RUWS), nd is presently undergoing testing on the Pontoon Implcement Vehicle [PIV). This pper wi?? discuss not only the results of these tests but the difficulties encountered due to "Murphy's Lw". It is hoped tht this pper wil provide the reder with better understnding technologicl the of dvncements obtined in the re of remote work from tethered vehicles nd some of the more criticl opertionl n design res to be encountered. 1. Introduction The primry intent of most ppers given t symposiums present to is recent technologicl dvncements. However, since writing the bstrct for this pper, I hve decided to use the utho& poetic license nd del more with opertionl the experience gined during my pst five yers with the Work Systems Pckge & ssocited Progrms. Although criticl technologicl res wil be discussed nd referenced s required, the intent of this pper is to tke step bck to the bsics ththe enyineer should bsing be t-se his designs upon. At times thengineer must return from chsing ptents or new dvncements in technology nd go bck to building the blocks tht provide successful system design, design tht cn counter Murphy's first lw: If nything cn go wrong, it wil, nd t the worst possible moment. Therefore, I wil discuss severl subsystem design res of underse vehicles nd work systems, res where dvncements in technology hve resulted in greter underse cpbility, nd res where engineering oversights could nd hve resulted in disster. Although I wil use the WSP s primry exmple of technologicl dvncement nd design pplictions, the comments in this pper re bsed on my experience in generl nd re not ment to reflect on the design or designers of ny specific system. But first, some bckground on the WSP. 2. Bckground The Work Systems Pckge (WSP), under the direction of the Nvl Se Systems Commnd, ws designed, fbricted nd is undergoing Opertionl testing t the Nvl Ocen Systems Center [MOSC) in Sn Diego (Reference 1). As prt of the Deep Ocen Technology (DOT) project, the WSP progrm ws initited in Februry ofiscl yer 1972, by NOSC working in conjunction with Bttelle Institute, Civil Engineering Lbortory nd the Dvid Tylor Nvl Ship Reserch nd Development Center, AnnpoTis. The Work Systems Pckge (WSP) is designed to provide verstile work cpbility when mounted s unit on the Nvy's Cble Controlled Underwter Recovery Vehicle (CURV 111) or the Remote Unmnned Work System (RUWS) unmnned cble -control led submersible vehicles, nd the ALVIN, SEACLIFF, nd TURTLE mnned vehicles. In ddition, it cn be positioned nd control led by divers or operted independently from surfce support ship for opertions t shllow depths without the need for submersible. The system ws designed to ccomplish complete work tsk or1 the ocen floor without the necessity of resurfcing for tool interchnge. Potentil tsks include slvge, recovery, instlltion nd repir opertions. Bsic components of the work pckge (Fig. 1) include two simple outer mnipultor rms without elbow functions tht ct s "grbbers" or restrining/holding rms to stedy the vehicle or hold smll work pieces. 743 U.S. Government work not protected by U.S. copyright.

2 ~ ~ ~ ~. Box ATOR HYDRAULIC POWER UNIT "GRABBERS Figure 1. WSP s it would pper mounted to the mnned submersible ALVIN. A centrlly locted seven-function mnipultor rm cn select, interchnge nd operte vriety of hydruliclly ctuted tools. Included in the tool storge box re tools perform cble cutting, synthetic line cutting, nut torquing, jcking, prying, wire brushiny, swing, grinding, drilling, tppiny? nd stud driving. An electriclly-drlven hydrulic pump unit supplies the power to most tools. Electric power is supplied to the system from self-contined bttery pckge. Control of ll opertions nd functions is provided throuyh mu1 tip1 exed telemetry circuit from vehicle. the Pressure tolernt electronic nd hydrulic components operte t full mbient pressure in oil-filled, pressure-compensted enclosures. Upon completion of ssembly, checkout nd preliminry tests, the WSP ws mted to the CURV I11 for its first mjor in-wter test. The WSP underwent six weeks of opertionl testing the t Nvy's Sn Clemente Islnd test fcility in fiscl yer Such tests s underwter docking with submerged test fixture, tool exchnges nd opertion, object identifiction nd recovery, nd simulted flight recorder recovery were successfully completed. The superior operbility of the system, the short-time (2 to 2 1/2 minutes) required for remote tool exchnges underwter nd the successful performnce of complicted recovery sequence requiring exchnge nd opertion of nine different tools nd bits in 2-1/2 hours, (Figure 2) chieved, nd in mny cses, surpssed originl design gols. SEQUENCE OF OPERATION 1. EXTRACT THE DRILL MOTOR AND A 1-INCI-l DRILL BIT 2. DRILL ACCESS HOLES IN THE ALUMINUM COVER TO ALLOW SPREADER INSERTION 3. EXTRACT THE SPREADER INSERT INTO THE ALUMINUM SKIN AND OPEN THE SKlN TO &LO% 1NSERTION OF THE JACK A.. REPOSITION ~ THE VEHICLE TO ALLOW USE OF THE JACK 5. EXTRACT THE JACK INSERT AND SPREAD APART THE ALUMINUM RIBS ALLOWING REMOVAL O'F THE "FLIGHT RECORDER 6. EXTRACT THE IMPACT WRENCH AND SOCKET AND REMOVE THE '/-INCH BOLT FROM THE "FLIGHT RECORDER" 7. ATTACH A BUOY-LINE TO THE 'FLIGHT RECORDER" AND REMOVE IT FROM THE TEST FIXTURE USING THE MANIPULATOR 8. EXTRACT THE CABLE-CUTTER AND CUT THE ELECTRICAL CABLE... AHACHED. TO THE ~ "FLIGHT RECORDER" 9. EXTRACT THE SYNTHETIC LINE-CUTTER AND CUT THE 1-INCH NYLON LINE ATTACHED TO THE "FLIGHT RECORDER" RELEASING IT TO FLOAT TO THE SURFACE Figure 2. Simulted "flight recorder" recovery scenrio Following the successes t Sn Clemente Islnd, the WSP ws flown to NOSC's Hwii Lbortory for interfce nd testing with the Remote Unmnned Work System (RUWS). The WSP nd RUWS were mted nd operted in the RUWS test pool preprtion in for support of the Lrge Object Slvge System (LOSS) opertionl demonstrtion the Nvl Costl Systems Center (NCSC) during the fiscl yers 1976 nd The WSP/RUWS ws flown to Pnm City, Florid, where it successfully completed support of the LOSS opertion. The systems esily performed such tsks s midwter docking, cble cutting, stud driving, messenger line ttchment, nd ir hose ttchment using quick-disconnects. The WSP ws then returned to Sn Diego where it ws prepred for n extensive lbortory evlution of the operting chrcteristics of the system. The lbortory evlution resulted in complete time notion bseline description of the Work Systems Pckge upon which ny opertionl scenrio cn be simulted resulting in projection of both operting time nd power consumption by the bseline ksp design. With this bseline, subsystem prmeters cn be chnged nd the 744

3 sensitivity of these chnges on the system cn be determined providing the design engineer with n excellent tool for future work system designs (Reference 2). Presently, the NSP is undergoing studies ddressing the integrtion of it with the Pontoon Implcement Vehicle, in nticiption of testing which wil del with the re of Deep Ocen Recovery. 3. Systen Concept/Configurtion One the of hrdest portions the of design problem is tht of coming up with the proper concept or system configurtion. This usully rises from the lck of proper definition of the systems mission. For exmple, the rnge missions of in underse work covers such res s inspection of offshore drilling pltforms with smll remotely -controlled vehicles, recovery of downed ircrft or ordnnce, up to recovery of entire submrines. Along with mission definition, the identifiction of the operting criteri is lso essentil. Chnges in opertionl se sttes, current velocities, depth requirements, mneuverbility, nd work cpbility, ll hve considerble impct on the initil design concept nd should, therefore,be ccurtely identified in the erly stges. For successful design, these criteri must be relisticlly determined. The usul pproch, tht the system to be designed wi 11 be "THE SYSTEM" tht wil do everythiny, nytime, nywhere, cost nothing nd be completed yesterdy, is totlly unstisfctory. However, time nd time gin system designs begin with this "pie in the sky" ttitude. Subsequently, lot of time nd money is wsted chsing totlly unrelistic yols. The pproch of beiny relistic nd determining exctly wht the opertionl criterire, bsing the system design round these criteri, nd sticking to them is of the utmost importnce. The lws of nture re not going to chnge for the design engineer, nd he who enters the re of underse design with the optimistic pproch tht this ll-encompssing, generl system wil be ble to do nything he desires, usully wil end up with system tht compromises the mission nd opertionl criteri, system tht insted of doing one thing very well, does few things mediocre. 4. Opertionl Support/Hndling Although most spects this of pper pply eqully to both mnned nd unmnned submersibles, this section, more thn others, wil primrily ddress the tethered, unmnned system. Too often in system designs, tunnel vision results in the overlooking of severl criticl res. Ares such s: -Identifiction opertionl the of pltform. -How wil the system be trnsported to the operting loction? -How wil the system be hndle during the opertion? -kill the hnd1 ing system keep the tether out of criticl dynmic rnge? The Tether - The link which llows mn to mke his presence felt to the depths of the ocen, while he remins topside in n ir-conditioned environment where cn control the opertions below the surfce in sfety nd comfort. The tether - the wek link of the unmnned submersible. kith ll the dvntges ssocited with tethered submersibles, the tether design nd its ssocited equipment is by fr the most criticl re the entire of system. Assuming you hve cble with the proper configurtion nd strength, its is termintion cpble of tking the stresses imprted on it by the cble dynmics? Hs the hndling system tht you hve come up with ssured you ththe cble wil not enter snp lod region where it or the termintion cn be quickly dmged? You my sy "this is only design problem nd cn be overcome," nd this is herd quite often when it cones to tetheredesign. You my be right, but if you re cn you ensure tht the pilot of the vessel you re operting froln won't bck over your cble nd sever it? Once gin, you my sy "tht wil never hppen to me," tht your cble design is dequte, the dynmics hve been tken into ccount, nd you wil operte from ship tht wil not give you this kind of problem. Tht is gret on pper, but when you get down to the hrd fcts, life is not lwys bed of roses, nd severl of those "it cn't hppen to me" problems re listed in Figure 3. The list in Figure 3 is only out of my bckground, nd I'm sure it would grow considerbly if it hd been reserched tking into ccount ll of the offshore industry. mtter short, no In how sophisticted nd elborte your submersible design is, if you lose your tether nd cn't communicte with it, it wil do none bit of good. The engineer who tkes short cut in the cble dynmics design of the system becuse he sees light t the end of the tunnel, my find out tht the light is nother trin. VEHICLE STATUS FAILURE Lost (1 978) Tether Termintion Lost/Recovered (1979) Tether Termintion Lost/Recovered (1979) Tether Entngled Lost/Recovered (1979) Tether Entngled/Broken Severed/Recovered (1979) Tether Severed by Ship Figure 3. Five Recent Vehicle Ctstrophies 745

4 Following closely behind the se stte induced cble dynmic problems the is problem hndling of the vehicle system during lunch nd recovery. Quite often the system being designed wil operte off ships opportunity of which my impose severe problems during lunch nd recovery in hevy ses. Since the designer cnnot lwys be ssured of the type of crne or system to be used to lunch the vehicle, he must ensure tht the method of rigging the vehicle for lift fil-sfe. is For exmple, lifting hrdwre should be kept cler of criticl system components, where during hndling rough ses dmge to those systems is lmost certin. Also, the lift points must be ttched to portion of the system which in no wy cn fil or come off either through overstressing or component or weldment filure. Expensive systems hve often been dmged due to filure to properly integrte the hndling system. This integrtion should be done very erly in system design nd not done in retrospect. These filures cnnot only cuse loss of n entire vehicle or progrm, but cn esily result in personl injury. Once gin, s the following list indictes, Murphy something hs for everyone who sys "it cn't hppen to ne": -Figure 4 shows dmge to the CURV 111 frme resulting from n ccident tht occurred during shipbord hndling. -WSP/RUWS dropped pproximtely two inches due to weldment filure t lift point in 1977 which resulted in over one week of down time during t-se opertions (Fi yure 5). Figure 5. Effect of 2" drop of the NSP on 11 of its 16 mounting bolts. In n effort to heed our own words, the upcoming opertions with the WSP wil utilize hndling system which remins on the vehicle nd provides single point for remote ttchment, s opposed to the six point lift system previously used which required divers in the wter to mke the ttchments. When plcing you re vehicle in the wter next to ship or tking it out, there is no time for mistkes, nd the system tht you re using should be filsfe, simple, remote, nd quick, thus providing mximum sfety to divers, the crew, nd the vehicle. 5. Structure Figure 4. CURV I11 Frme Dmge Structure, the skeleton of the vehicle, mechnicl the "bg" the of design engineer. Wht technologicl problem does there exist with the structure? None relly, but how often did the sleek hydrodynmic vehicle which ws presented in the erly concepts end up being the cluge tht is sitting on the lbortory floor? How often did improper system integrtion into the structure, problems with corrosion, or poor design for mintinbility hmper n t-se opertion? Unless you re reltively new in the field, then your nswer is probbly "more thn one time." Let's look t these 3 res more integrtion, specificlly: system corrosion, mintinbility. Since most the of subsystems on vehicle re reltively smll compred to the overll size of the vehicle, the bsic impct of poor systems integrtion, other thn the effect of the overll vehicle design nd efficiency,is the ese in which you.cn get to the subsystem nd perform preventive mintennce or repir. However, one subsystem in tethered design stnds out foremost, nd tht the is 746

5 buo3ncy system. The buoyncy of system is often considered lte in the design; but in fct, it cn hve substntil impct on the system design nd should be integrted in the initil stges. For exmple, the WSP buoyncy mteril, needed to provide neutrl buoyncy while submerged, ccounts for one-third of its in-ir weight. The integrtion of subsystem this substntil must tke into ccount viewing requirements, mnipultor movement requirements, ccessbility other to subsystems, long with the structurl integrity required to withstnd the ocen environment. The ffect of cble dynmics, wve-slp, system nd dynmics during lunch nd recovery cn impose severe loding problems on lrge mount of buoyncy mteril, especilly if this mteril is hnging on for der life nd not integrted properly into the vehicle itself. The second re to ddressed be concerning the vehicle structure is tht of corrosion. "No problem," sy? you "A good fresh wter wshdown fter ech opertion should tke cre of it." In generl this is good philosophy; however, in relity, Mother Nture hs nother ide. Since I hve become involved in underse design, I hvencountered two schools of thought corrosion on prevention. The first, nd lest used, is presented by those involved long term underse corrosion studies. This thought is tht if you don't do nything to lrge structure, i.e., don't pint or nodize it, then it wil corrode slightly ll over nd you won't hve corrosion concentrtions which would cuse filure. The second school of thought is tht ifs best to either nodize, pssivte, or pint the structure thus protect iny it froni yenerl corrosion problems, such s overll corrosion, but mking it more susceptible to corrosion concentrtions when this protective surfce is dmged. However, both schools of thought miss one very criticl spect of corrosion. This spect rises in the re of crevices or recessed loctions which re usully hrd to get to nd entrp some slt wter. As is usully the cse these re the res where stinless steel hrdwre or components re used in conjunction with the luminum structure housing. or However, with the ppliction of nodic cotings nd dequte preventive mintennce this problem cn be delt with. These nodic cotings lso require ppliction to those res which re hrd get to for to preventive mintennce. This includes ll metl interfces nd not just those of dissimilr metls, since entrpped se wter long with res of reduced oxygen due tight to interfces cn set up detrimentl corrosion cycles. This becme very pprent to those of the first school of thought upon retrieving lrge corrosion test pltes nd finding tht there ws little corrosion on the plte itself, but severe corrosion below the teflon mounting wshers used to insulte the test plte from the mounting fixture. 'Just remember, rwphy is lwys looking over your shoulder; he ws looking over mine in 1977 when the WSP lifting filure ws prtilly cused by corrosion. Therefore, I offer the third school of thought. You cnnot overpint, overnodize, overpssivte, pply too much protective coting, or perform too IiluCh preventive mintennce. If you don't pply enough protection to your system keep or tht protection mintined you re going to hve problems, even in the most sophisticted nd well designed systems. Also, proper system design the erly in stges help to eliminte res conducive to corrosion nd designing for esy preventive mintennce cn he1 p solving the problem of corrosion. Following long the pth of preventive mintennce is the mintinbility of system. MAINTAINABILITY? Wht! You hve never herd of the word mintinbility? I would not be totlly surprised. Unfortuntely, too mny tody's of engineers hve been stuck in n office designing systems for so long tht they hve forgotten wht it's like out in the rel world when this perfect design decides to no longerun. Repiring n inoperble system t-se, in bd wether bord rolling ship, especilly when you hve just run out of drmmine, is not the most plesnt experience. Wht most engineers need, nd I think should be required of ny tsk tem, would be spending few weeks t-se correcting the previous engineer's mistkes. Especilly, when he cn't quite get the to subsystem due to improper systems integrtion therly design stges. becuse Just innovtive the engineer mnged to plce squre peg in round hole does not men tht the optimum design ws chieved. Srcsm you sy? Possibly. But remember the following: Operting costs t-se re phenomenl. When you re cutting 3 to 4 digit figures from your system design costs, scrificing proper design nd mintinbility to chieve this, your dily losses while t-se duriny filure of thisystem to operte my esily be in the 4 to 5 digit rnge, nd if you re working for one of the oil compnies, it my be pushing 6 digit figure. Therefore, t l costs, design preventive for mintennce nd mintinbility of ny given system nd hve enough spre prts on hnd to complete the repir job. A beutiful system tht does not work nd cnnot be esily fixed is of no use. 747

6 6. Mnipultors To mechnicl engineer the mnipultor suit is usully the most dynmic nd first ddressed in the design of more optimized underse system. Shouldn t more sophisticted, dvnced dexterous, mnipultor be used in your next vehicle system so tht you cn do your job much fster? Being mechnicl engineer, nd therefore going ginst my bsic design philosophy, I hope to refute this ide. In order to perform ny type of work opertions in the ocen, the work system mnipultors must be cpble of two things: (1) ttch to nd mintin the work system orienttion the work site, nd (2) provide rnnipult l on the required to operte tools to perforrii remote work tsks. The system must hve this cpbility not only on the bottom, but lso during mid-wter opertions. In nswer to the first requirement, the WSP design evolved into one requiring three mnipultors. Previousubmersibles hd no more thn two mnipultors; one to hold the vehicle in position, the other to perform work opertions. This configurtion cused the system to be pushed wy due to the rection forces of the work mnipultor, usully resulting in the breking of tools or intolerble completion times of required tsks. To eliminte this problem the WSP uses two mnipultors to ct s grbbers or restrining rms while the third nd more dexterous mnipultor is used to perform tool exchnge opertions nd the work tsks. For the second requirement, let s ddress grbbers the nd mnipultors seprtely. The desiyn the of grbbers should be reltively simple. Their primry function is to hold the vehicle in plce, so they do not need the dditionl elements such s elbows or extensive movements in ech joint. The criticl point often overlooked in the design of grbbers to ct s restrining rms is tht not enough ttention is pid to wht they re ctully restrining. The grbbers must be designed with enough strength to hold.the entire vehicle in plce in the mximum expected cross current. The drg forces imposed on the vehicle by the cross current cn be quite substntil nd cn esily dmge the grbbers. This fctor, long with the following, resulted in breking one of the WSP grbber wrists during t-se Opertions. The second fctor ws requirement to move TV cmers from one grbber to the other in order to view the undocking procedure. This resulted in the removl of the first grbber followed by the binding of the second grbber due to its bering the entire vehicle lod in the cross current. To llevite this problem, in future WSP opertions, the system hs been modified so tht the ctivtion of single switch now opens nd retrcts both restrining rms of the system, therefore ensuring tht no single rm is over-stressed during n undocking opertion. And now let s discuss the hert of the system, the dexterous work mnipultor. when ttempting to identify the desired chrcteristics of the work mnipultor, engineer the fced is with severl lterntives such s control, rte mster/slve control, force feedbck, or computer control. The optimum system wil depend entirely on the criticl tsks to be performed by the system. For exmple, if you re in spce ttempting to grb stellite s it psses you, then you hd better hve mster/slve system incorported into the design. If you re underse ttempiny to disssemble nd disrm mine, you hd better hve very dexterous mnipultor with some force feedbck cpbilities. However, if your primry purpose is hevy duty underse work, then the choice of force feedbck or mster/slve mnipultor system my not optimize the design, but quite the to contrry my subtrct from it. For more sophisticted mnipultor penlty must be pid in cost, re1 ibility, nd mintinbility lthough certin tsks cn be performed quicker. The design of the system must be ddressed to tht tsk which wil occupy the gretest percentge of the work to be performed. After ll, the mnipultor tht my do things twice s fst but only works hlf the time is not very good trde-off. This is not to sy tht excetlent sophisticted mnipultors do not exist, but for certin jobs they my not be required. For exmple, when doing underse tsksuch s drilling, tpping, bolting, swing, cble cutting, etc., such s the WSP hs been designed to perform, it hs been found tht more sophisticted mster/slve design does not sve tht much time. In dditon, if you re nticipting work t-se with tethered submersible where you hve no time limit s to how long the tsk cn nd my tke then you do not necessrily wnt to hve your rm stuck in the mster mnipultor for n eight hour period. this In cse, simple rte controlled mnipultor usiny series of toggle switches is more thn sufficient. In fct, recent studies hve shown tht designing better mnipultor not is necessrily the plce to strt in designing more efficient system (Reference 2). Figure 6 shows tht in opertions without tools, the mnipultor is used only 33 percent of the time, the cmers moved 17 percent of the time, while the opertor requires 50 percent of his time to decide wht to do on his next move. Therefore, 748

7 other res, such s reducing opertor decision time cn hve gret impct on the overll system design with mximum pybck of cutting the operting time in hlf, while instlling mnipultor which cn do its tsk twice s fst wil possibly only reduce the overll operting time by round 16 percent. Although more dexterous, fster operting mnipultor my id reducing opertor decisions, the primry effect wil only be cross the mnipultor opertion time. AVERAGE OPERATION LOW SPEED PUMP IDLE TIME DUTY TIME those tsks performed. t the work site which re only repeted few times, progrm control cn be used if the design is quite efficient. This requires tht the opertor needs only to push button to begin recording the progrm nd press button to store the progrm, llowing the opertor to recll the progrmmed pth t ny given time. This progrmmed pth, which would of course include ny opertor errors; my not be the most efficient pth to the work site; but, the fctht ll decision time in mking movements hs been eliminted, it cn be repeted in both the forwrd nd reverse direction in considerbly less time. The vilbility of this technology exists nd hs been demonstrted. Now, with the ddition of the progrm control to the mnipultor, it is n esy tsk to utomticlly progrm the pn nd tilts to follow the mnipultor once nd gin reduce opertor's the overll time by 11 to 17 percent by not hving to stop nd move the TV cmers. Therefore; when requested to optimize mnipultor system on limited budget, remember tht highly trined opertor with simple relible mnipultor my very possibly be the optimum design. OPERATION WITH TOOLS (%) 1 AVERAGE OPERATION I I I I I 1 TIME // / / / LOW SPEED PUMP 59% TOOL IDLE TIME 37 (22)' LOW SPEED PUMP DUTY TIME / / HIGH SPEED PUMP TIME DUTY (4)/// 22 TOTAL POWER CONSUMPTION (2' 23 (1) LIGHTING = 0.75KW (2) LOW SPEED PUMP IDLE = 1.55 KW (3) LOW SPEED PUMP DUTY = 2.00 KW (4) HIGH SPEED PUMP DUTY = 3.97 KW [ON-OFF ONLY) 'IT IS ASSUMED THE MANIPULATOR IS NOT BEING MOVED DURING TOOL ACTIVATION Figure 6. Opertionl Time Distribution of the WSP (percent) Now, ssuming you hve rte controlled mnipultor nd you wish more sophisticted system, next then recommended step would only the be instlltibn of position feedbck system. Nith dequte position feedbck vilble, computer control the of mnipultor is esily chieved. After ll, the most efficient opertor is one who thinks instntneously, i.e., computer. The computer cn esily be pplied to repetble tsks, thereby totlly eliminting 50 percent of the operting time. Figure 7 shows the effects of mnipultor progrmmer on tool nd bit exchnges on the Work Systems Pckge. It cn seen be tht ll in cses, the experienced opertor ws outdone by the mnipultor progrmmer. In the cse of r REDUCTION OPERATORS 82% 57% REPLACE 33% ACQUIRE 1.00 BIT REPLACE 0.74 BIT % Figure 7. Comprison of WSP tsk times (minutes) under direct opertor control nd computer control. 7. Viewing "Viewing - no problem,"you sy, "We'll just throw couple of cmers down there nd see- wht we're working on." This my be esier sid thn done. Remember if you cn't see it, you cn't do it, nd hving picture on. television monitor does not necessrily men you cn see wht you wnt to The do. tsk t hnd my be re-entering smll hole, for which generl overll view television cmer my not be suitble, but one with zoom lens would be optimum. But possibly the desired objective is to view the overll system so tht the- sttus of ll mnipultors ppendges my be known. Thisttus my be required t more thn just the forwrd operting point of the vehicle or system. Therefore, the engineer hs the qundry of I'DO I choose the wide ngle cmer, zoom lens cmer, stndrd cmer, or possibly stereo pir?" The choice OF ny cmer revolves round the bsic fct tht the wter must be cler enough to view the opertion. Grnted, developments in technology hve provided coustic imging systems which llow viewing through totlly 749

8 opque wter nd "touch nd feel " mnipultor systems which pint picture of wht they re feeling during ny work opertion thus llowing the completion of reltively simple tsks. However, these rexceptions to the rule nd remember tht your primry subsystem design should be bsed on tht sitution or opertion tht you wil encounter the highest percentge of the time. Therefore, we re once gin returned to the question of which cmer do ;,we use. The nswer to this question is "use them ll". If you hve wide ngle or zoom requirement then instll tht cmer in the proper position, i.e., use multiple cmers {Reference 3). A simple instlltion of severl cmers nd few video switches wil give the opertor lt the perspectives nd fields of view required to perform tsks the effectively. Just becuse you cn only view 1 to 2 monitors t time when doing n opertion does not men tht you re limited to tht number of choices of pictures. You hve never seen footbll gme with one mn wlking round with cmer trying to prcrvide dequte coverge for television. There exists control room with severl video inputs in which the primry opertor chooses the one to be presented, nd underse opertionshould no be different. This does not only pertin to the work re of the vehicle but to the sttus of the port, strbord, ft, top, nd bottom res of the vehicle. The two entnglement probl ets mentioned previously in Figure 3 my hve been prevented with dequte viewing systems. You my possibly come up ginst the problem tht you do not hve the bndwidth vilble in your cble tcr trnsmit tht mny TV pictures. Testing hs shown tht the opertor cn work esily with "qusi-rel-time" televisin pictures, those being defined s providing sml Fer number of 'N lines t slower rte. Although less dt Is being trnsmitted to the opertor, for ll prcticl purposes he sees no difference in the qulity of the picture. With these types of processing of the television system, up to 4 gusirel-time televison pictures cn be sent over single coxil cble previously cpble of trrrsmittting only one rel time TV picture. And through the use of video switches the number of TV pictures vilble to the opertor cn be gretly incresed. 8. Comnnd nd Control As is usully the cse in pper or report written by n engineer of one discipline, res relting other to engineering disciptines re usully covered in less detil. Not wntlng to n be exception to the rule, this pper wil be no dlfferent, *en ddresslng the world of electronics, it utterly mzes me tht this field of engineers cn keep up with technology tht is moving so fst. These engineers seem to hve the cpbility of tking myrid of blck boxes nd pint portrit using circuit bord s plette nd soldering iron s brush. Although some their of chievements my seem remrkble, electronic engineers long with everyone else, esily ft1 prey to some of the criticl design res. Therefore, few conunents to those designing the electric? electronic or systems of submersibles follow: -Mintinbility, once gin dominting fctor. Bsic electronic design esily lends itself to modulrity during repir or mintennce. Therefore, the design of electro9ics nd their enclosures should keep in mind ese of ccessbility nd repir so tht minimum down time results from ny electronic component filure. -Redundncy of n electronic systwn is gret sset for successful opertion. Along with the redundnt system, system which hs the down link nd up link signls unssocited wil? provide better feedbck to the opertor. It is hrd to isolte problem when the feedbck dt you re receiving is possibly being ltered by tbe problem itself. -The veb-i-cle system should be simplified s much s possible, thus trnsferring s much sophisticted equipment s possible to mndynmic, controlled topside environment. Although the previous comments my be brief in eutline, they re monumentl in heir effect Z f pplied. 9. Conclusion Uesign of system for underse use is esy, design of one tht wrks is not. If you hve red this pper nd feel your intelligence hsbeen insulted, you re one of the engtneerr to whom thls pper ws not written. However, if single conment or point in this pper hs opened your eyes or mde you question your pproch of design in ny given re, then I feel the time spent presenting thfs pper ws more thn rewrded. The deep ocen is one of the few unconquered frontlers left, nd engineers desiring this chllenge wtl hve n invigortfng, frustrtlng, but fulfiling creer, The conquest of the cen is the gretest existing chllenge to mn. The chllenge of beting Mother Nture t her own gmel But one wrning, It hs been pssed on to me by n untmpechble swrce thst Mother Nture's lst nme is "Wurphy". 750

9 REFERENCES 1. Estbrook, N., H. Wheeler, D. Uhler, nd D. Hckmn, "Development of Deep-Ocen Work System," IEEE Ocen 'X, Wernli, K.L., "Development of Design Bseline for Remotely Controlled Underwter Work Systems," Nvl Ocen Systems Center, IEEE Ocen '78, Wernli, K.L., "Design for Remote Work in the Deep Ocen," Nvl Ocen Systems Center, AShE Winter-Annul Reeting,