Department ofVeterans Affairs

Journal of Rehabilitation Research andDevelopment Vol. 31 No . 3, August 1994Pages 236–244

CL NICAL REPORT

Evolution of mechanical fingerspelling hands for peoplewho are deaf-blindDavid L. Jaffe, MSE, Department of Veterans Affairs Medical Center, Rehabilitation Research andDevelopment Center, Palo Alto, CA 94304

Abstract—People who are both deaf and blind canexperience extreme social and informational isolation dueto their inability to converse easily with others . Tocommunicate, many of these individuals employ a tactileversion of fingerspelling and/or sign language, gesturesystems representing letters or words, respectively . Thesemethods are far from ideal, however, as they permitinteraction only with others who are in physical proxim-ity, knowledgeable in sign language or fingerspelling, andwilling to engage in one of these "hands-on-hands "communication techniques . The problem is further exac-erbated by the fatigue of the fingers, hands, and armsduring prolonged conversations.

Mechanical hands that fingerspell may offer asolution to this communication situation . These devicescan translate messages typed at a keyboard in person-to-person communication, receive TDD (TelecommunicationDevices for the Deaf) telephone calls, and gain access tolocal and remote computers and the information theycontain.

Address all correspondence and requests for reprints to : David L . Jaffe,VA Medical Center, Rehabilitation Research and Development Center(153), 3801 Miranda Ave ., Palo Alto, CA 94304.Dexter's design and development was conducted under DOE-NIHRGrant No . G008005054, with assistance from The Smith-Kettlewell EyeResearch Foundation.Dexter II was developed with Department of Veterans Affairs, Rehabil-itation Research and Development Service Core funding.Gallaudet Hand support was provided by the National Institute onDisability and Rehabilitation Research (NIDRR) Project H133G80189-90 under contract to Palo Alto Institute for Research and Education(PAIRE) and supervised by Gallaudet University.RALPH was supported by Department of Veterans Affairs Rehabilita-tion Research and Development Service, Rehabilitation Research andDevelopment Center, Palo Alto, CA, Core funds .

Key words : communication devices, deaf-blindness,fingerspelling.

INTRODUCTION

Communication is such a natural and integralpart of one's daily activities that it is taken forgranted. Today instantaneous international commu-nication is an affordable reality . For example, it isnot uncommon for a person with access to theInformation Superhighway (Internet) to retrieveinformation and post messages from/to a dozendifferent countries during a single on-line session.Cellular telephones and telephones in airplanes arethe latest advances in mobile communication tech-nology. These systems, which permit communica-tion with anyone, at any time, and from anylocation, suggest that being without communicationis unnatural and personally limiting . Yet there aremany people for whom interpersonal isolation is away of life . These are the estimated fifteen thousanddeaf-blind men, women, and children in this countrywho cannot even communicate with another personon the opposite side of the same room, let alonewith someone on the other side of the world . Thereare veterans who incurred deaf/blindness as a resultof a service-connected injury.

Usher's SyndromeThe majority of adults who live with the dual

sensory loss of deafness and blindness have a disease

236

237

CLINICAL REPORT : Mechanical Fingerspelling Hands

called Usher's syndrome. It manifests itself asdeafness at birth, followed by a gradual loss ofvision commencing in the late teens or early twen-ties. Although Usher's syndrome accounts for 15percent of congenital deafness, it is usually notdiagnosed until the onset of the visual impairment,or even later . Unaware that special education prepa-ratory to visual loss may be in order, these childrenare usually enrolled in programs for the deaf wherethey learn fingerspelling and sign language (and/orlip reading and speech) in addition to reading print.Because they are identified as deaf, Braille skills arenot taught.

When loss of vision is superimposed on deaf-ness (as happens with Usher's syndrome), a majorchannel of receptive communication is lost, usuallyresulting in an enormous social and informationalvoid.

Alternate Methods of CommunicationBraille is a potential tool for relieving some of

this isolation . In addition to providing a system forreading, a mechanical representation of Braille hasbeen incorporated in electronic aids such as theTelebraille (a TDD with a 20-character mechanicalBraille display), to enable deaf-blind individuals toreceive information in both face-to-face and remotecommunication situations . Learning Braille as anadult, however, is difficult . The very act of learningto read Braille may be considered a final admissionof blindness.

Many deaf people use sign language whichincorporates more global movements and configura-tions of the hands and arms, as well as facialexpressions, to represent words and phrases . Theysupplement sign language with "fingerspelling," agesture system in which there is a specific hand andfinger orientation for each letter of the alphabet, tocommunicate words for which there is no signedequivalent (such as proper names).

Tactile Fingerspelling and Sign LanguageA common communication technique used with

and among deaf-blind people is simply a hands-onversion of fingerspelling and/or sign language(Figure 1) . Instead of receiving communicationvisually as deaf people do, the deaf-blind person'shand (or hands) remain in contact with the hand (orhands) of the person who is fingerspelling orsigning . The full richness of the motions present in

Figure 1.The manual fingerspelling alphabet.

sign language can not be conveyed in the tactilemode required by a deaf-blind individual . Instead,each word of a message is typically spelled out, oneletter at a time with the fingerspelling technique.(Although many Usher's Syndrome patients canspeak intelligibly or use sign language, others usefingerspelling for expressive communication as well .)

While such tactile reception works fairly wellfor many deaf-blind people, it does have significantdrawbacks . Since very few people are skilled in thesemanual communication techniques, there are very

238

Journal of Rehabilitation Research and Development Vol . 31 No. 3 1994

few people with whom to "talk ." The need forinterpreters poses still other problems : locating,procuring, and paying for the interpreter service . Aproblem unique to deaf-blind individuals is thatmany interpreters are accustomed to being "read"visually by deaf clients and may not be comfortablewith the physical restrictions involved in signingwhile another person's hands are touching theirs . Inaddition, the rapid fatigue resulting from thesetactile methods often requires two interpreters sothat a break may be taken from continuousfingerspelling or signing. The need for an interpretermay also intrude on the deaf-blind individual'sprivacy and place him/her in an extremely depen-dent situation due to the complete reliance on aninterpreter for any communication.

THE FIRST ROBOTIC FINGERSPELLINGHAND

MethodIn an attempt to alleviate these problems, the

Southwest Research Institute (SWRI) in SanAntonio, TX, conceived and developed a mechani-cal fingerspelling hand in 1977 (1) . This early devicedemonstrated the feasibility of transmitting linguis-tic information to deaf-blind people by typingmessages on a keyboard connected through electricallogic circuitry to the mechanical hand . The handresponded by forming the corresponding letters ofthe one-hand manual alphabet . To receive theinformation, the deaf-blind user placed his/herhand over the mechanical one to feel the fingerpositions, just as he/she would with a humanfingerspelling interpreter . This system finally en-abled deaf-blind people to receive communicationsfrom more than a few select individuals; anyonewho could use a keyboard could express themselvesto the deaf-blind person through the mechanicalfingerspelling hand.

ResultsWhile the SWRI system demonstrated the

concept's feasibility, it had many technical short-comings : not all of the letters could be properlyformed, it operated more slowly than a humaninterpreter, and the fluidity of motion which seemedto greatly enhance the intelligibility of receptivetactile fingerspelling was lacking. In addition, any

changes in timing or how the hand formed theletters had to be achieved through mechanicalalterations of the hardware . This limited the device'sflexibility as a research tool.

DEXTER

MethodIn 1985, the Rehabilitation Engineering Center

of The Smith-Kettlewell Eye Research Foundationsponsored a class project conducted by four gradu-ate students in the Department of Mechanical Engi-neering at Stanford University to design and fabri-cate an improved state-of-the-art fingerspelling hand(2-7) . Its major goal was to develop a system withimproved timing and easily modifiable finger posi-tions . These qualities were realized in a new roboticfingerspelling hand named "Dexter" (Figure 2.)

Mechanical Hardware

Dexter looked like a mechanical version of arather large human hand projecting vertically out ofa box. The four machined aluminum fingers and athumb were joined together at its palm . All digitsoperated independently of each other and had arange of motion comparable to human fingers . Thethumb was jointed so as to allow it to both sweepacross the palm as well as move in a planeperpendicular to it . A pneumatic rotary actuatorallowed the palm to pivot in a rotary fashion around

Figure 2.Dexter fingerspelling hand .

239

CLINICAL REPORT : Mechanical Fingerspelling Hands

a vertical steel rod much the way a human hand canpivot from the wrist—except that Dexter couldachieve a full 180° pivot.

All Dexter's finger and thumb motions wereactuated by drive cables . Pneumatic cylinders pulledthese cables which flexed the individual fingers andthumb, while spring-driven return cables extendedthe fingers. The cylinders, in turn, were activated byair pressure controlled by electrically operatedvalves . These valves were controlled by a microcom-puter system. The actuating equipment and valveswere housed in two separate assemblies below thehand.

Computer Hardware

The original student design was based on anIntel 8085 STD-bus "target system" used in ME218(Smart Product Design Course) at Stanford . Itconsisted of the 8085 microcomputer, Forth pro-gramming language, memory, and counter/timersupport . The timer generated the signals that deter-mined the rate of hand motion and how long eachfinger position was to be held . The additionalcircuitry needed to control Dexter was fabricated ona standard card which plugged into the target systemcard cage. A single external 12 volt power supplyactivated the 22 valves under computer control.Digital output port latches received data from themicroprocessor, while Darlington power transistorsprovided sufficient current to activate the electricallycontrolled valves . Letters to be displayed on thehand were entered on an IBM-PC computer'skeyboard which was connected by a serial link to thetarget hardware.

Dexter's hardware was subsequently revised atthe Rehabilitation Research and Development Cen-ter (RR&D), Palo Alto, CA, to consist of a Z80microprocessor card, two medium-power drivercards, and a high-current DC power supply allhoused in an STD bus card cage . The microproces-sor card itself contained counter-timers, memory,and serial interfaces. Commercial medium-powerDC driver cards replaced the student-built wire-wrapped version and the power supply for operatingthe pneumatic valves was included within the STDchassis. An Epson HX-20 laptop computer's key-board and display were employed to communicateuser messages over a serial link to the self-containedtarget system .

Computer SoftwareThe Forth programming language was chosen

because 1) its design cycle is approximately eighttimes shorter than assembly language, 2) it is aninteractive and compact high-level language that canemploy assembly language for critical timing andinterrupt service routines, 3) it uses a standard hostcomputer connected by a serial port to the targethardware for development, and 4) the applicationprogram can be stored in non-volatile memory afterit is fully tested.

The student-designed Forth software was sub-stantially updated by RR&D to 1) execute fromnon-volatile memory, 2) accommodate menu-drivenalteration of critical parameters such as timingvariables, 3) allow new characters typed on thekeyboard to be accepted while previous ones werebeing fingerspelled, and 4) incorporate both modemand serial input of characters.

OperationThe microcomputer and its associated software

controlled the opening and closing of the bank ofvalves which directed air pressure to specific pneu-matic cylinders which pulled on the drive cableswhich were the "tendons" of the fingers. As amessage was typed on a keyboard, each letter'sASCII value was used by the software as a pointerinto an array of stored valve control values . Thestates (open or closed) of all 22 valves were specifiedby three bytes. Two to six valve operations, eachseparated by a programmed pause, were needed tospecify the finger movements corresponding to asingle letter . The hand could produce approximatelytwo letters per second, each starting from andreturning to a partially flexed neutral position.

An additional bit in the valve control byte triadwas used by the software to determine whether thecurrent finger position was an intermediate or finalletter position. Different programmed pause timeswere associated with each of these two situations.

Although the mechanical hand could not ex-actly mimic the human hand in fingerspelling all theletters (such as the special wrist and arm motionsrequired in J and Z), the fact that Dexter alwaysproduced the same motions for a given letter was animportant factor influencing its intelligibility . Theinter-letter neutral position was another unnaturalfeature of the design that did not accurately reflect

240

Journal of Rehabilitation Research and Development Vol . 31 No. 3 1994

human fingerspelling and limited the speed of letterpresentation . Despite these shortcomings, users ofDexter had little difficulty in accommodating to it.

ResultsDeaf-blind clients of Lions Blind Center

(Oakland, CA) served as subjects for the initialtesting of Dexter . They were able to identify most ofthe letters presented by the robotic hand without anyinstructions, and in less than an hour were correctlyinterpreting sentences . Equally important was theirpositive emotional reaction to the hand . Theyseemed to enjoy using it and seemed to be intriguedby its novelty . There were no negative commentsmade concerning its mechanical nature or any otheraspect of the system.

DEXTER-II

MethodDexter-II was built by a second Stanford

student team in 1988 as a second-generation com-puter-operated electro-mechanical fingerspellinghand (8,9) . This device, like its predecessor, trans-lated incoming serial ASCII (a computer coderepresenting the letters and numbers) text intomovements of a mechanical hand . Dexter-11's fingermovements were felt by the deaf-blind user andinterpreted as the fingerspelling equivalents of theletters that comprise a message (Figure 3).

Dexter-II was approximately one-tenth the vol-ume of the original Dexter mechanical system. Itwas designed by three Stanford graduate mechanicalengineering students and employed DC servo motorsto pull the drive cables of a redesigned hand,thereby eliminating the need for a supply of com-pressed gas. A speed of approximately four lettersper second, double that of the original design, couldbe achieved with the improved design.

Mechanically, the hand (a right hand the size ofa 10-year-old) was oriented vertically on top of anenclosure housing the motors . Each finger could flexindependently . In addition, the first finger couldmove away from the other three fingers in the planeof the hand (abduction) . The thumb could move outof the plane of the palm (opposition) . Finally, thewrist could flex. Each hand motion was driven by itsown servo motor connected to a pulley . Wire cablesanchored at the hand's fingertips and wound around

Figure 3.Dexter II fingerspelling hand.

pulleys served as the finger's "tendons ." As themotor shafts were powered, they turned the pulleys,pulling the cables, to flex the fingers . Torsionsprings at the "knuckles" separating the Delrinfinger segments provided the force to straighten thefingers when the motors released tension on thecables.

Dexter-II's computer used the STD-bus enclo-sure, Z80 microprocessor card, and Epson HX-20computer from Dexter . Two commercial countertimer cards replaced the medium-power driver cardsand were used to produce the pulse-width modulatedwaveforms required to control the DC servo motors.In operation, a message was typed on a keyboard(the Epson HX-20) by a nondisabled person . Eachletter's ASCII value was used by Dexter-II's com-puter software to access a memory array of stored

241

CLINICAL REPORT: Mechanical Fingerspelling Hands

control values . This data stream programmed thepulse-width modulation chips to operate the eightservos and flex the fingers. The resulting coordi-nated finger movements and hand positions werefelt by the deaf-blind communicator and interpretedas letters of a message.

ResultsDexter-II was first tested by a deaf-blind

woman who is extremely proficient at "reading"tactile fingerspelling . She provided many suggestionsfor improving Dexter-II's letter-shape configura-tions. Later, it was introduced to 12 deaf-blindpeople during an annual retreat in Sacramento,California.

In June of 1989, about 20 deaf-blind attendeesat the annual Deaf-Blind Conference in ColoradoSprings had an opportunity to experience Dexter-II.The device was also exhibited at the 1989 RESNAConference in New Orleans, Louisiana, and at theInvenTech meeting in Anaheim, California in Sep-tember, 1989. In all cases, the deaf-blindindividuals' ability to initially understand Dexter-IIvaried considerably. Some were able to understandDexter-II immediately, while others had troubletranslating a few letters.

Although neither Dexter nor Dexter-II couldexactly mimic human hand movements in finger-spelling all the letters, they were able to display closeapproximations that have proven to be easy to learnby deaf-blind users . An advantage of Dexter-II'smechanical system was that it always produced thesame motions for a given letter—an importantfactor in recognizing its fingerspelling "accent ."

FINGERSPELLING HAND FOR GALLAUDET

MethodIn 1992, Gallaudet University (Washington,

DC), with funding from the National Institute onDisability Rehabilitation Research (NIDRR), con-tracted for the design and construction of twothird-generation fingerspelling hands for clinicalevaluation (10,11) . These units were to be smaller,lighter, and more intelligible than previous designs(Figure 4) . The effort involved two facilities : RR&DCenter designed the new mechanical and computersystems, while the Applied Science and EngineeringLaboratories (ASEL) (Wilmington, DE) provided

Figure 4.Fingerspelling hand for Gallaudet University.

critical hand position data and addressed telephoneinterface access issues.

Mechanical Design

In this design, as in Dexter-II, each handmotion was driven by a servo motor connected to apulley. A cable was wound around the pulley,routed up the finger, and attached to its tip . Thefingers themselves were constructed of Delrin seg-ments attached to each other by a strip of carbonfiber . The carbon fiber provided the flexible hingeand restoring force necessary to extend the finger.When the motor shaft and pulley rotated, the cablewas pulled and the finger flexed . When the motorshaft rotated in the other direction, the tension onthe cable was released and the finger straightened.

Computer Hardware DesignA Z180 SmartBlock (Z-World, Davis, CA) 8-bit

microcontroller accepted RS232 serial data and

242

Journal of Rehabilitation Research and Development Vol . 31 No . 3 1994

choreographed hand motion by controlling eight DCservo motors. The controller itself was compactenough to be packaged within the hand's enclosure.

Computer Software Design

The Forth programming language provided asimple user interface, allowed modifications to thefinger positions, and permitted the system parame-ters to be altered . Fingerspelling movements in thisversion were much more fluid due to the eliminationof the inter-letter neutral position . The softwareincludes two finger position tables for each letterpair . One table is permanently installed, while theother can be altered using a built-in editor . Thisfacility permits movements to be changed to en-hance a particular-letter pair's readability.Fingerspelling speed was adjusted by a six-positionrotary switch . The first five positions selectedincreasing speeds by altering the length of the pausesbetween letters, while the final position offered aprogrammable speed.

ResultsASEL tested and configured the fingerspelling

hands for use with TDDs . The letters were furtheroptimized for improved recognition . Nine deaf-blindpeople tested the hands over a 2-month period atGallaudet . One individual was able to interpret all10 simple sentences without error . Other users wereable to understand 70 percent of the sentences.Comparable performance was achieved with singleisolated letters . The users identified confusing lettercombinations and suggested improvements for acommercial prototype (12).

RALPH

MethodA fourth-generation fingerspelling hand called

RALPH (for Robotic ALPHabet) has been con-structed by RR&D to serve as a basis for technologytransfer and commercialization (Figure 5) . Specifi-cally, this design implemented an improved mechan-ical system.

Mechanical Design

RALPH's design is similar to the hands de-signed for Gallaudet . In this device, however, a new

Figure 5.RALPH fingerspelling hand.

mechanical system replaces the pulleys and car-bon fiber strips. Each hand motion is driven bya servo motor connected by a lever arm to a rod.The rods push and pull a system of linkages thatflexes the individual fingers and the wrist . Theelimination of the pulleys makes RALPH morecompact and able to fingerspell faster . Its fingers areactively extended, unlike Dexter-II or the Gallaudethands .

243

CLINICAL REPORT : Mechanical Fingerspelling Hands

Computer DesignRALPH utilizes the same computer hardware

as its predecessor and its Forth software is organizedin 17 modules . These modules provide enhance-ments for the Forth kernel, an assembler (includingroutines that implement special I/O instructionsused by the microcontroller), an ANSI displaydriver, serial port utilities, timer port utilities, clockutilities, servo motor pulse width modulation gener-ation, speed switch driver, interrupt routines, inputbuffer software, timing control, hand data storage,fingerspelling algorithm, hand position editing sup-port, and the user interface . As with the Gallaudethand, RALPH's software provides a menu-drivenuser interface, allows the finger positions to beedited, and permits alteration of system parameters.

Operation

Any device that produces RS232 serial data,including terminals, modems, computers, OCRscanners, speech recognizers, or modified closedcaption systems, could be used to control RALPH.The user interface is implemented as a menu systemthat provides easy access to the unit's variousfunctions including displaying and setting themicrocontroller's parameters, testing the hand mo-tions, editing hand position data, and enteringletters to be fingerspelled.

In the fingerspelling mode, key presses areentered on the keyboard . The hand's softwaretranslates these key presses into commands for theDC servo motors . As the motor shafts rotate, theypush/pull on the rods that connect to the fingers'mechanical linkages . It is by this coordinated seriesof motor commands that keyboard input is trans-formed into choreographed motion representingfingerspelling.

The mechanical system provides sufficienttorque to move the fingers against the resistance of auser's hand, but not enough to cause any pain orinjury if the user's finger happens to get caughtunder RALPH's . The servo motors simply stallwhen their torque limit is exceeded.

ResultsOver a 2-day period at ASEL, RALPH was

evaluated for approximately 8 hours by two individ-uals. One was familiar with the Gallaudet

fingerspelling hand and was completely deaf andblind. The other had not used mechanicalfingerspelling hands before and had some residualsight and hearing capabilities . They both reportedtrouble with some letters, but the first user was ableto correctly identify isolated characters over 75percent of the time.

When short sentences were presented, the expe-rienced user completely understood approximately75 percent of the sentences . Furthermore, in each ofthe failures, after a second presentation, the sen-tence was either understood in its entirety or justone key word was incorrectly identified.

Additionally, both users appreciated the newrounded design of RALPH's finger segments be-cause they felt more natural than the hands built forGallaudet.

DISCUSSION

Beyond evaluation, technology transfer issuesmust be addressed . The market for fingerspellinghands needs to be assessed . A collaborative effortwith a manufacturer will be required to move thisdevice out of the laboratory and into the hands ofdeaf-blind people . A potential manufacturer hasbeen found in southern California . Current plansinvolve pursuing Small Business Innovative Re-search (SBIR) funding for technology transfer andthe additional design changes to address remainingconcerns identified during Gallaudet's evaluation.

A potential solution exists for the provision offingerspelling hands to deaf-blind people. WithinCalifornia (and some other states), all telephonesubscribers support a fund which provides telephoneaccess equipment for persons with disabilities . Un-der this program, approved commercial versions ofthis fingerspelling hand could be furnished at nocharge to deaf-blind people.

Research has also been done on a "TalkingGlove" (13). This device consisted of an instru-mented glove worn by a deaf-blind person thatsensed the flex of each finger . Its pattern matchingsoftware translated the wearer's fingerspelling ges-tures into letters that could be displayed or vocalizedby a speech synthesizer . This system could providean expressive communication channel for RALPH'susers .

244

Journal of Rehabilitation Research and Development Vol . 31 No . 3 1994

CONCLUSION

RALPH was intended to serve deaf-blind usersas a complete receptive communication system, notjust a means of receiving information in face-to-facesituations . Its ability to respond to computer inputmeans it can be interfaced to a TDD to providedeaf-blind people with telephone communication . Itcan also be connected to computers to provideimproved vocational and avocational potential tothe deaf-blind community.

All encounters with RALPH and previousfingerspelling hands have been enthusiastic, posi-tive, and at times, highly emotional . The in-creased communication capability and ability to"talk" directly with people other than interpret-ers are powerful motivations for using finger-spelling hands . They have the potential to providedeaf-blind users with untiring personal communica-tion at rates approaching that of a human inter-preter.

A commercially available product may helpalleviate some of the extreme isolation experi-enced by people who are deaf and blind . It is adevice that performs a worthy task—that of en-abling human beings to communicate with eachother.

ACKNOWLEDGMENTS

The following people and facilities were involved inthe evolution of mechanical fingerspelling hands:

Rehabilitation Research and Development Center,Department of Veterans Affairs Medical Center, PaloAlto, CA—David L . Jaffe, Douglas F . Schwandt, andJames H. Anderson; Stanford student group (Dexter)—John Danssaert, Alan Greenstein, Patricia Lee, and AlexMeade; Stanford student group (Dexter II)—DavidFleming, Gregory Walker, and Sheryl Horn; Smith-Kettlewell Eye Research, Palo Alto, CA—DeborahGilden; Gallaudet University, Washington, DC—JudithE. Harkins, Ellie Korres, and Carl J . Jensema; AppliedScience and Engineering Laboratories, Wilmington, DE—Richard Foulds, William Harwin, and Timothy Gove;Palo Alto Institute for Research and Education, PaloAlto, CA—David D . Thomas ; and from the University ofCapetown Medical Center, Capetown, South Africa—David A. Boonzaier.

This effort would not have been possible withouttheir ideas, energy, and commitment .

PHOTOGRAPHIC AND LINE ARTACKNOWLEDGMENTS

Figure 1, The manual fingerspelling alphabet, wassupplied by the Helen Keller National Center for Deaf-Blind Youths and Adults . Figure 2, Dexter fingerspellinghand, was supplied by the Rehabilitation Research andDevelopment Center, Palo Alto VA Medical Center.Figures 3, 4, and 5 are photographs taken by CurtCampbell, Palo Alto VA Medical Center, Medical MediaProduction Service.

REFERENCES

1. Laenger CJ Sr, Peel HH . Further development and testsof an artificial hand for communication with deaf-blindpeople . Southwest Research Institute, March 1978.

2. Danssaert J, Greenstein A Lee P, Meade Alex . Afinger-spelling hand for the deaf-blind . ME210 FinalReport, Stanford, CA : Stanford University, June 1985.

3. Gilden D. A robotic hand as a communication aid for thedeaf-blind . In: Proceedings of the Twentieth HawaiiInternational Conference on System Sciences, Honolulu,HI, 1987.

4. Gilden D, Jaffe DL . Dexter : a mechanical finger-spellinghand for the deaf-blind . J Rehabil Res Dev Progr Rep1986 :24(1) :328.

5. Gilden D, Jaffe DL. Dexter : a helping hand for commu-nicating with the deaf-blind . In: Proceedings of the 9thAnnual RESNA Conference, Minneapolis, MN, June1986 :49-51.

6. Jaffe DL. Speaking in hands . SOMA : Eng Hum Body1987 :2(3) :6-13.

7. Gilden D, Jaffe DL. Dexter : a robotic hand communica-tion aid for the deaf-blind . Int J Rehabil Res1988 :II(2) :198-9.

8. Jaffe DL. Dexter II : The next generation mechanicalfingerspelling hand for deaf-blind persons . In: Proceed-ings of the 12th Annual RESNA Conference, NewOrleans, LA June 1989 :349-50.

9. Jaffe DL. Dexter : a fingerspelling hand . OnCenter -Technol Trans News 1989 :1(1) :l.

10. Jaffe DL. Third generation fingerspelling hand . In:Proceedings of the Technology and Persons with Disabili-ties Conference, Los Angeles, CA, March 1993 . In press.

11. Jaffe DL . The development of a third generationfingerspelling hand . In: Proceedings of the 16th AnnualRESNA Conference, Las Vegas, NV, June 1993 :161-3.

12. Harkins JE, Korres E, Jensema CJ . Final report : arobotic fingerspelling hand for communication and accessto text for deaf-blind people . Washington, DC : GallaudetUniversity, 1993.

13. Kramer J, Leifer L . An expressive and receptive commu-nication aid for the deaf, deaf-blind, and nonvocal . In:Proceedings of the Annual Conference, IEEE Engineeringin Medicine and Biology Society, Boston, 1987 (Suppl):20 .