THE. EASY CHAIR
`
`DESIGNED BY :
`JAMES P. WILLIAMS
`GREGORY F. WELCH
`
`SCEA Ex. 1033 Page 1
`
`

`
`E . E.T . 490/491 SENIOR DESIGN PRO~ECT
`
`THE EASY CHAIR
`
`INDEX
`
`TOPIC
`
`Abstract • . . . •
`Introduction •
`Infra red Touch-Pad
`Scop~ • •
`Body
`
`The Row Decodlng Block •
`The Column Decod1ng Block
`The Ex tra Oecod1ng Block .
`The Touch - Pad Block
`•
`•
`.
`The Row/Columr, Detect Block
`The Menu Select Det~c t Block
`General D1scuss1on
`Ultrason1c Rang1ng
`Scop~: • •
`.
`Body
`
`The D1rectional Transducer Block
`The Tone Generator Block •
`The Additional PIA and Timer Blocks
`General Discussion
`Computer and Motor Control
`Scope .
`Body
`
`The Computer Block
`The Motor Control Blo ck
`General D1scuss1on
`C.onclu s1 on .
`Proposed T1me L1ne .
`F1gures IP1ctorials>
`Current Easy Cha1r Software List1ng
`Cost1ng
`B1bl1ography
`
`PAGE
`
`l
`2
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`3
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`4
`4
`5
`5
`6
`7
`9
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`10
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`1 1
`12
`12
`1~:
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`14
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`14
`14
`16
`17
`18
`APPENDIX A
`APPENDIX B
`APPENDIX c
`APPENDIX D
`
`I.
`
`SCEA Ex. 1033 Page 2
`
`

`
`E.E . T . 4 90/49 1 SENIOR DESIGN PROJECT
`
`THE EASY CHAIR
`
`FIIJLIRE LIST
`
`TITLE
`
`FIGURE
`
`Eas y Cha1 r Block Diag r am
`In frared Touch-Pad
`Blo c k Diagram
`Schemati c . •
`P1ctor1al • .
`Ultras on1c Rang1ng
`Schemati c
`.
`Timing Di a gra m
`Pictc•rla.l
`Tone Generat o r
`Schemat1 c
`Motor Contro l
`Schemat1c
`Computer Scema.t1cs
`CPU •
`.
`.
`.
`.
`Memory
`.
`Tuner Group, I/0 Address1ng Group
`Ser1 a l Group
`I n terr·up t Selec t or Grc•up
`Parallel Group,
`Addit1onal Parallel Group •
`Bus Connector, Power Supply •
`
`1
`
`2
`3
`4
`
`5
`(:,
`7
`
`8
`
`9
`
`10
`1 1
`12
`13
`14
`15
`16
`
`II.
`
`SCEA Ex. 1033 Page 3
`
`

`
`ABSTRACT
`
`-ne follow1ng report 1s a g~neral synoos1s of ideas and
`oes1gns used 1n the oevE>lopmttnt of the Easy Cha1r, a
`m1croprocessor cont r·olled wheelctoalr for sma ll ch1ldren w1th
`muscular dlsorders .
`
`The 1n1t1al wneelcha1r come5 equ1ppeo w1th a Oamaco 088
`Add- On power un1t . Thls un 1t come s complete w1th toatter1es, t he
`0r1ve un 1ts <motors an d con t rollers>, an d a proport1 onal Joystlck
`controll e r .
`The touch-pad, ult r asonic k lt, and the compute r are
`the th r ee e x tra components to be added f or additional contr o l and
`safety .
`
`Spec1f1cat1 o ns f or the Easy Cha1r were ou t l 1 ned by an
`Occupat1onal Therap 1st, Phys1cal T herap1 st, and a cl ass room
`teacher f rom The Wabash Center 1n Lafayette, Ind1ana .
`Th1 s
`outl1n1ng was ass1sted toy George Karl1n, Spec 1a l Education
`proJeCt coor01nator at Purdue Un1vers1ty, Lafayette, lndlana.
`
`The or1g1nal 1dea for the whe~lcha1r was conce1v~d by G~orge
`E:arlln, wh1le wcorl(lrog w1tto srroall
`toarodlcapp.d ctnldr·en b·~th at
`Purdue Un1vers1ty a nd The Wabash Center . George Karl in also
`a cted as a po-between for the des1gners and therap1sts,
`throughout the des1gn .
`
`The touch-pa d 1s v a lue d at ar o u nd $21 3, the unltrason1c
`system at a round $ 342, and the computer at aroun d $363, wit h a
`total co st of around $1 053 . All of the development components
`a re be1ng be1ng paid f or by The Wabash Center, w1th the f1nal
`prototype be1ng released to them.
`
`The tnrwe sect1ons reported on hereafter, all work very wel
`The ultrason1cs prwsently convey per1meter
`seper~tely .
`1nfornoat1oro, the touch-pad can to• used to conf ~ gur-e the systeno,
`and the computer- 1s runn1ng, controlling the other systems .
`
`What rema1ns 1n the proJeCt IS toas1cally t o complet~ the
`mo tor con tr' ol system ,
`to comb1ne, test a nd modify t he seperate
`components, to package the result 1ng hardware, and to polish off
`the syste m softwa r-e so that 1t w1 ll a llow the users to conf1gure
`the cha1r for the 1 r spec 1f1c needs .
`
`1
`
`SCEA Ex. 1033 Page 4
`
`

`
`INTRODUCTION
`
`For many years, smal' ch1ldren w1th muscular dtsorders h~ve
`had severly l1m1ted opportun1t1es to acqu1 re any amount of
`noab1l1ty . Because of th 1s lac~ of mob1l1ty, they nave a lso had
`l1m1ted opportunit1es to 1n1t1ate commun1cat1on w1th others,
`i1m1t1ng furttoer ttoetr
`learnHoQ Capato1 l1t1es .
`
`The 1dea behind a m1croprocessor controlled wheelcha1r ( the
`Easy Cha1rl 1s to prov1de a mode of transportat1on for very young
`Chlldren w1th muscular d1sorders . Because the users will be so
`young, typically two to s1x years old, the cha1r should be
`equ1pped w1th a var1ety of dev1ces which w1ll not only allow them
`to control movement w1th lim1ted muscular force, but will also
`protect them from any undes1reable c1rcumstances.
`
`Such devices include a method of 1nput such as a toucn-pad,
`lrequ1r1ng m1n1mal or no muscular for ce to actua te>
`, an
`ultrason1c rano1ng Eystem to mon1tor tne chalr 1 s per1meters, and
`a computer to control these oev1ces 1n a fash1on wh1ch 1s
`transparent to the user, <see F1gure 1).
`
`From th1s point on, there w1ll three majo r sections to the
`report .
`The f1rst sect1oro w1ll cover the touch-pad, the second
`w1ll cover the ultrason1c rang1ng, and the th1rd w1ll cover the
`computer and the motor control.
`
`2
`
`SCEA Ex. 1033 Page 5
`
`

`
`THE INFRARED TOUCH-PAD
`
`SCOPE
`
`The Infrared touch-pad 1s to be kroown as the 1nput system
`far the control of the cha 1r.
`It 1s currently thought of as the
`only d1rect method of 1roput wh1~h w1ll be assoc1ated w1th the
`f1nal whee lc halr. Therefore, 1t must meet many requ1rement~
`wn1ch allow 1t to alter the current system conf1gurations, or
`just to control the cha1r .
`
`In conce1v1ng the 1dea for the touch-pad, the follow1ng
`spec1fica t1ons were used as gu1del1nes to facilitate design .
`
`It was determined that a touch sens1t1ve 1nput surface
`requ1r1ng m1n1mal pressure would best suit the needs of the small
`children .
`The system needed to be adaptab le to different
`ch 1 ldren, som~ of whom are 1ncapable of generating h 1gh response
`force.
`
`Tne touch-pad should use a common med1um for set- up, to
`1ncrease the 1ndependance of the system and 1ts users. Th1~ 1s
`to say that 1t should be possible to s1mply plug 1n or unplug the
`t ouch-pad, and to switch between the pad and the current JOystick
`wlth l1ttle or no effort .
`It should be totally self-contalned as
`a un1t, e l ectr on 1cs and al l . Aga1n, th1s would 1ncrease the
`lndependance of the system .
`
`The touch-pad should be constructed 1n such a way that it
`could be attached to the current center off -set mounting arm of
`the wheelcha1r (whlch sw1ngs out of the way of the user>, w1th
`the opt1on of rest1ng on the lap tray of the chalr. These two
`methods w1l 1 result 1n the touch-pad be1ng as ambidex trous ~s
`posSible.
`
`The un1t should be large enough to be ~as1ly v1ewed and
`touched, but small enough so as not to be obtrus1ve to the us~r
`and the wheelcha1r. A general touch-pad area of ten 1nches by
`ten 1ncnes was set For 1n1t 1al d1mensions .
`
`The Sl~e and locat1ons of the symbols on the
`to control the wheelchair) must be programmable .
`acconoodate d1fferent ranges of noot1on .
`
`touch- pad (used
`Th1s w1ll
`
`The touch-pad must be mo1sture proof. Children with such
`nana·~~ts as c~rebral pdlsy frequenTly have ural nootor prub l~ms
`w~lCh r es ~l~ 1 n excess1v~ dro~.l~~. Any re asona ·l~ amount oi
`n1ol~tur·~ s~ould not c~u~~ tt1e wt·~~l ·:h~lr tv n.~1TUf•'~-~r,.
`
`In the past, 1t toad been thought that a total hardware
`
`3
`
`SCEA Ex. 1033 Page 6
`
`

`
`solut1on was the most ~el 1 able and cons1stant route to take .
`Howeve~. afte~ carefully study1ng that ~oute, and testtng the
`resu l ts, 1t was determ1ned that a comb1nat1on of approx1ma t ely
`equal amounts of hardware and software would al l ow the most
`fle x lble o:leslgfl .
`The fol 1 0Wll19 secti<•riS descr·lt.>e the present
`solutlOfl, and how 1t 1s 1mplemwnted.
`
`BODY
`
`BLOCK DIAGRAM
`
`The block d1agram for t he touch- p a d con s ists of s1 x main
`blocks . These blocks 1 nclude the ~ow decod1ng
`t s elect1ngl block,
`the column decoding block, t he extra decod1ng block <wh1ch
`1 nclude s the menu- select decod 1ng a nd the ul t r a sound direc t 1on
`llght decod1ngl, the touch- pad block, the ro w/column de tect
`block, and the menu-select detect block .
`Ea ch of thes e blocks
`w1l l be d1scussed further 1n the follow1ng sect1ons <se e also
`&1~ure 2, B l oc k D1agram l .
`
`1 • THE ROW DECOD I N13 BLOCI '
`
`The row decod1ng block 1s one such block where the
`seven b1t control word wh1ch 1 s sent to the touch- pad
`c1rcu1try 1s 1 nterpreted to select a ce~ta1n
`L ED/phototranslstor pa 1r .
`
`The de c odlng 1s a c~omp l 1 s hed by s e nding the least
`s1gn1f1cant four of t he seven b1ts as a nibble which g1ves a
`zero through f1fteen <F He w ) count, and then br1ng1ng one of
`three ch1p select l1nes h1gh, 1n part1cular the row decoder
`Chlp select line ( see f1gure 3-1> . To accompl1sh th1s, a
`74154 4 to 16 l1ne decode r 1s used. The outputs of tllll
`74154 a~e low when they are selected, so they are used to
`prov1de a ground path fo r
`the 1nfrared LE Os and
`thus al l ow1ng them to oe turned on on l y
`Dhotot r an~1st o rs ,
`when they are selected .
`
`It 1s appropr1ate at this time to re- state the fact
`that the select l1nes are used t o select both an LE D and a
`phototrans1stor . W1th th1s scheme, 1f the~e 1s noth1ng
`block1ng the bea m pa t h from the LED to t he phototrans1stor,
`t hen the phototrans1stor should be turned on.
`
`II . THE COLUMN DECODING BLOCK
`
`'the s a ntE(cid:173)
`;-.s. lnro!: "t
`: r1
`T"~ -:olutT1fl o~ c <•O i rt? l••.:•ci~ ..=-u rJC: tl on s
`~ a S~lO~ a s th e ~o~ o e: o~ - ~9 b 1 oCi' .
`The only d lff~ r e ~~~ 1 -
`tt,a t <•f t~ • ., se- lec t
`l 1ne wh 1c ~' 1s useei to s '" l t:<. t the <: (•l •~ mn
`decod1np ch1p, also a 74154 . Of the three se l ct l1nes
`
`SCEA Ex. 1033 Page 7
`
`

`
`<btts> from the seven b1t word mentioned, one 1s used to
`select the row decoding chtp, one the column decod1ng chip,
`and one the e x tra decoding ch1p .
`To select the column
`pa1rs, the .:col Ulllro s<?le•:t b1t must b.;, high .
`
`Aga1n, 1 n the sam" fQ.shloro as the row decod1ng, t.~olS.
`t• l ock select!> certatro LED/ptovt•:.tranststc<~" pau·s to t•e
`observed by the detect1on c1rcu1try .
`
`I II. THE EXTRA DECOD I NG BLOCK
`
`Again, the baste f unct1on of the extra decod 1 ng block
`1s the same a s
`t ha t o f
`t he row a nd col um n deco d ing blo c ks .
`However, this block serves no one s 1ngle f unc t ion such a s
`row or column decod 1 ng .
`
`t o reflect the odd or ' extra
`The term extra 1s mean t
`decod1ng that 1s done by thl~ block. At th~ present time,
`1t serves two ma1n furocttons; to select oroe of the f1ve
`menu-select LED/phototrans1stor pa1rs for observation. and
`also to momentarily select other dev1ces sue~ as l 1ghts
`whiCh w1ll ass1st ttoe user 1n determ1n1ng whlch per1meters
`are be1ng warned about by the ultrason1cs .
`
`I n refertng to f 1gure 3-1, 1t should be noted that the
`five ' menu select ~ l1nes are passed through trt-state
`buffers before they are connected to t he LED/phototra n s istor
`pa1rs . Th1s 1s because smaller LEDs an~ phototra ns1stors
`had to be used for the ftve menu select patrs (to f1t
`between the column pa1rs 1n the paa) . These smaller
`phototranststors had lower off-state resistance, wh1ch
`caused problems when they were not selected . Normally when
`a patr 1s not selected, +5 volts ~~ connected to the cathode
`o~ the LED and to the em1 t te r oF the phototrans1stor .
`Th 1s
`would not allow etther to be turned on . W1th these ftve
`menu select pairs however, the +5 volts <seen when not
`selected) caused the menu-select detect circu1try to send •
`touch message to the computer . Therefore, the trt-state
`buffers were used, wh1ch present a n open c1rcuit 1n the1r
`non-selected st a te .
`
`This extra decoding devtce could be thought of a s an
`e x tra computer port, with the only difference <whtch is a
`atsadvantage) be1ng that the outputs are not latched •n
`thetr selected states . However, for the present t1m~, th1•
`1s ro~· t rot- c ..:: ssar·y, a roc
`rroonoent-::tr y s&lctlo:•ro Wlll wo:•r·;-· flro&.
`
`Th1s ~lock contains the actual touch-pad w1th the LEDs
`and phototrans1stors mounted 1n 1t, and the slot for the
`
`5
`
`SCEA Ex. 1033 Page 8
`
`

`
`selected merous to be 1nserted 1nto (see f1gure 4 ) . Along
`the vert1cal a nd hor1:ontal sides of the sunken touch area,
`are al t ernate l y mounted 32 1nfra red LEOs and 32
`phototrans1stors, one a cross from eac h LED . These pairs were
`alternated to reduce the amount of light being rece1ved 1n
`error . The LEOs a nd photot r ans1stors we re c a re f ully a l1gned
`£o as to ach1eve the ma•1mum s1gnal rec1e~~o when a s1gnal
`1s sent . Each of the cathodes of tne LEOs a long w1th the
`em1tte rs o f the phototrans1stors ac ross from them, are t1ed
`t o the select l ines of t he 7 4154s <see a lso T he Row Decoder
`Bloc k and The Column Dec oder Block) .
`
`The t ouch-pad a l so contains f1ve seperate pa1r s wh1ch
`are mounted perpendicular t o the row and column pairs, along
`the edge of the pad. These serve the purp o se of a llow1ng
`the computer t o detect wh1ch menu 1s 1n the pad . The paper
`menus h ave f1ve c orrespond1ng holes wh 1ch c a n be cut open or
`le ft 1ntact <clo se d), represent1ng z eros and ones .
`
`The anodes of a ll of the infrared LEOs (both
`r·ow/column LEDs a nd menu-select LEOs) are t1ed high through
`a s1ngla ser1es l1m1t1ng res1stor . Therefore, a ga1n when
`the pa1r is sel ecte d , and the cat hode lS ta ken to ground,
`tho= LED turns on .
`
`Eventually, all of t he select a nd the detect c1rcu1try
`w1l l be packaged a long the lef t a nd r 1ght s1de o f
`the
`t oucro- pad, a nd a ll C•f th1s w1ll be enclosed 1n one case .
`Th 1 s w1 ll allow t h e
`t ouch-pad to be tota lly se lf-c ontalned
`l indepe nd ant l .
`It w1ll be t1ed to the computer by a ten
`conductor c ab le wh 1ch w1ll 1nclude the f our pair select
`1 iroes, the thr·ee ch1~· !'>elect b1ts, onE-
`touch return l1ne, +5
`volts and ground .
`
`V.
`
`THE ROW/COLUMN DETECT BLOCK
`
`Th1s block is where the phototrans1stor statu s 1s
`t ransformed 1nto a level that can be 1nterpre te d by the
`computer .
`
`The co lle ctors of • 1 1 of the phototrans1stors are t1ed
`togethe r, because only one 1s selected at a time . These are
`then pulle6 h 1 9h through a s1ngle pull-up res1stor 1100k
`ohms) . When any one of the 32 row/column phototrans1stors
`1s selected, an 1nf rared beam of l1ght from the pa1red ~ED
`shou d Turn ~~ on, putt!ng the col e~tor voltage somcw~er.
`-~ ~th: le on~ lS ~electe~~ the bean: 1! ~~ocK~d,
`n~ar ~rour1d .
`t'rt~ ~.'tP .. •t<•t ,..oar·SJ.S·tOr- Wl ll l;)-: tur·nerj of-'i .
`Wt1~n Or't"., ttr~
`co11e(.tor V•)ltag c=- appr t:·~·:Jtt;-!· +5 volt! t•t-cause.- of :t.~ pu11-'.JP
`r esl~t' .;:.r.
`
`SCEA Ex. 1033 Page 9
`
`

`
`Because of the change 1n collector voltage from when a
`beam 1s blocked to when one 1s not blocked, the collectors
`a re the 1 nput to the row/column detect circu1try .
`Th1 s
`c1rcu1 t ry uses a pair of comparat ors, wit h re fe rences set by
`a 20k ohm potent1ometer set up as a vol tage d i v1der .
`
`The f1rst compara tor 1s set up in a n 1nvert1ng
`fash1 o n, so tha t when any coll e ctor vol t age is below the
`reference <no beam b lo cked>, the ou tput of the comparator is
`at positive saturation . However, 1f any coll ect or voltage
`swi ngs a bove the reference, the ou tput go es t o negat1ve
`saturation <close to ground >. This output 1s then used as
`the 1nput t o the second comparat or .
`
`This second comparat or has the s a me r eference voltage
`as t he first one, however, 1t is set up in a non-invert1ng
`fa sh1on .
`I t is used to clean-up the comparator signal .
`Whe n the select ed bea m 1s not b roken, the outp ut of t he
`f1 rst comparator Cwh1ch 1s the 1nput to the second> 1s h1gh,
`wh1 ch a l so send s the second conparator 1nt o pos1t1 ve
`saturat1on. This second output s1groal, called RCRET
`Crow/column ret ur n), 1s then passed throug h an OR gate wh 1 ch
`h a s one input tied low, to cl ean it up .
`
`Th1s cond 1t1 oned RCRET s1gnal 1s the n comb1ned wit h
`the MSRET s 1gnal <menu- select return> to prov 1de one sin gle
`RET <return) signal for the computer . This signal does not
`prov1de a hard wa re 1nterrupt, but is 1nstead polled by the
`s oftware as a sing le b1t 1 npu t
`t o a port.
`
`VI . THE MENU-S ELECT DETECT BLOCK
`
`The menu-se lect detect block has almost the same
`circu1try as the row/column detect block, w1th t he only real
`d1 ff erence be1ng the s1ze of the pull-up res1stor needed for
`the five smaller phototrans1stors (men u-s elect pa irs> .
`Otherwise, the opera t1o n 1s the same, w1t h the same
`circu1try repeate d s1mply to 1solate the menu-select return
`IMSRET I from t he row/column return <RCRET I .
`
`I t is appropriate at this time to note the reason for
`combining the three decoding chip selects w1th both the
`row/column detect and the menu- se lect dete c t <see f1gure 4,
`SCHEMATIC >. The reason 1s that 1f the neither the row or
`column ch1p is selected, then the RCRET s1gnal is high,
`falsely sign~l1ng a beam be1ng broken. The same problem 1s
`<=r .. :•:o.Jnter·.;o.j wtr.,n t ~~~ merou-s.,'<?o:t
`·=lo1t•
`lS root s.,l~cted, tt·e
`MSRET s1gnal 1s high, fals.::ly s1gnal1ng a
`t>eam being brol(ert.
`To el1v1at<? this problem, the row and column ch1p selects
`
`7
`
`SCEA Ex. 1033 Page 10
`
`

`
`are AND ' ed with the RCRET signal, and the extra chip select
`1s AND ' ed with the MSRET s1gnal. W1th this method, RCRET
`can only go h1gh when e1ther the row or column chips are
`selected. Also, MSRET can only go h1gh when the extra ch1p
`1s sele cted .
`
`The result1ng s1gnals are OR ' d together to form a
`s1ngle RET l1ne wh1ch 1s h1gh whenever a selected beam 1s
`broken. This l eaves the computer free to select e1the r a
`row, column or menu-select beam, and then determine w1th one
`line <RET> whether or not that beam is being broken .
`
`e
`
`SCEA Ex. 1033 Page 11
`
`

`
`GENERAL DISCUSSION
`
`As was ment1oned earl1er 1n the scope of t he project, the
`or1g1nal thou~ht had been that a total hardware system would be
`bast . W1th such a system, the computer would only have to
`respond to an 1nterrupt by the touch- pad, and dur1ng 1ts servace
`r·equest, c~oecl· the pad to see wn1ch locat1 on had been touched.
`
`Al l of th1s cou l d have been prov1ded by sett1ng up a
`h a rdware clock which ran several counters . These counters would
`in turn select e a ch row pa i r, then e a ch column pair, a nd finally
`each menu- select pair . The maJOr disadvantage to this method was
`that the scan process would be set in one cer t ain fashion, unable
`to change as bet t er processes were discovered . W1th t he present
`method, the compute r supplies the count to the pa d, so i f 1t sees
`that the RET <return) line is hagh, then 1t knows that the beam
`Cpair) selected has been 1nterrupted or blocked .
`
`The current metho~ of us1ng anfrared l1ght beams, was
`dec1ded upon for v a r1ous reasons. Farst of all, other touch-pad
`schemes such as cap1c1t1va touch sensang, and pressure sens1t1ve
`membrQne type keypads, are all open to problems be c ause they are
`affected by water, or saliva in this case . Secondly land most
`lmportantl, breaking a l1ght beam raquares the least amount of
`pressure of any method stud1ed .
`
`The approach of us1ng 1dent1cal c1rcu1ts for the RCRET and
`the MSRET may at first seem redundant . Howeve r, because of the
`l1m1ted a mount of phys1cal space between the column LEOs and
`phototrans1stors, smaller vers1ons had to be used. These smaller
`vers1ons requ1red the same type o f detect1on c1rcu1try, w1th only
`a change an one res1stor. So, because the two blocks need to be
`electron1cally 1solated, and because the needed gat~s and
`•:on,paratc•rs (for du~•l1cate ciro:ultry) wer·e 1n fact av;;ulable, 1t
`was decided to dupl1cate the row/column detection for the
`menu-s~lect detection.
`
`Other reasons for choos1ng to duplacate the detect1on scheme
`are, not only the fact that no add1tional components were
`requ1red, but also that the or1g1nal scheme wa s tested and
`work1ng well.
`
`It is thought that 1n the future, there m1ght be the
`poss1b1 l1 ty of 1nterfac1ng a small lap- top computer which would
`allow the users to much more read1ly re-configure the touch-pad.
`With such a dev1ce, proorarns could be wratten in BASIC to ma~e
`~:Jr·c·gr·.;o.rmro lfl g OoUCto more u_ er-.:r 1erod . v .
`
`a
`
`SCEA Ex. 1033 Page 12
`
`

`
`ULTRASONIC RANGING SYSTEM
`
`SCOPE
`
`The ultrasonic rancting system is cons1dered Cl protective
`dev1ce. Its maJor funct1on 1s to prevent damage to the cha1r or
`inJury to its operator.
`It is also necesarv to protect other
`young children who maght be in Lhe operating C<rea of the chaar.
`
`In conce1v1ng the 1dea for the ultrasonic system, the
`follow1ng speclf1cat1ons were used as gu1del1nes to facil1tate
`design.
`
`The system is nol intended to be an intelligent system. That
`is, it 1s not to take offensive control at anytime as this would
`deter the user from learning to be 1n complete control of the
`wheelchair . It is hoped eveRtually the devlopment of the users
`sk1lls will allow the user full control w1thout per1meter
`sens1ng.
`
`The svstem should have some k1nd of aud1o and vtsual
`feedbac~. warn1ng the user of obstacles. caus1ng the cha1r t~
`slow or stop. As loud no1ses c"'n become botht>rsome, th1s optt.:Jro
`should be selectable.
`
`The system should sense any obstacle enter1nq into an
`approxamantly 2 foot d1stance suround1ng the chair, and should
`slow down accordtngly to allow the cha1r user to have more t1me
`to ma~e correct1ve act1ons. If correct1ve act1ons are not made 1n
`time, the cha1r will stop just before contact~ng the obstacle <
`less than 4 inches}.
`
`The ultr-asonic system as well as thE' other- systems should
`not destr-oy or deface the wheelchair in any manner. If any one
`part uf the chair is rnndered 1noppprative, the chetr 1tself
`cennot becomP useless. Jf a maJor failure occured, 1l should be
`easily possible to remove and ret1re the complete svtem.
`
`The ultrc<sonic system . as specified, per+orms ~wo funct1ons.
`It prov1des feedback to the user as to the approach of obstacles
`and 1t p rov ides a failsafe for stopping cha1r movement if the
`ch1ld does not respond to the approach warning.
`
`SCEA Ex. 1033 Page 13
`
`

`
`BODY
`
`BLOCK DIAGRAM
`
`The bloc~ d1agram for the ultrasonic system consists of four
`pr1ncipal parts. These include four directional transducers, the
`tone generator, the time base qenerator for d1 s tance calculat1on,
`and the interfac e
`t o the computer svstem. Eclc h of these bloc l s
`wtll be dtscussed tn the f o llowing sections ( see also f1qure 1.
`EASYCHAIR BLOCI' DIAGRAM
`l .
`
`I . THE DIRECTIONAL TRANSDUCER BLOC~
`
`The directional transducer block is the heart
`of the ranging s y s t e m. It consits of four comp lete
`and sep e rate rang ing transducers . Each of which
`contains a 50-kHz 300-volt electros tatic trans ducer
`and a small amount of drive circuity. Each
`transducer ts capable of ranging from 4 tnches to
`appro.< cot 1 y 35 feet v•i th 1 ess than 2/. mi' 1 mum error.
`( see fiq u re 5 l
`
`Th~ drive circuity constts of Tex as
`Instrument s SN28827 sonar ranoing module. Th1s
`module provides the 150-volt bias for the
`transducer and pulses the transducer with 16 cycles
`of 50-IH: 300-volt waveform. <see ftgure 6l. This
`man1fests 1tself as short audiable cltcl. Th1s
`ultrasonic click trcovel at the speed of sound (0.9
`ms/foot l unttl 1t striles an obstacle and 1ts echo
`returns to the transducer at the same speed. The
`module provtdes a controlable blanktng pertod to
`allow transducer vibration to dtsapate before it IS
`enabled to wait for a returning echo. All control
`s ignels a r e TTL compatible, but the echo output 1s
`of ope n co llec tor t ype a n d needs a
`p u ll-Ltp
`resistor 1n order to g e t
`r eliable TTL ~ 1 gna l .
`d
`
`t h ree me1 n contr o l stgn~ls. Th e
`Ther P. i'r e
`INIT* tnp u t starts the ranq1ng process by send1ng
`out the cl1ck . The BLNK* 1nput defeates lhe
`internal echo blanking . And the ECHO* output
`signals when the click is returned . All three
`signals are active low and their relationship to
`all the rest of the control l1ne is shown 1n figure
`6.
`
`'The only devat1on f ro•n Tt->: c<S I n ~ t r u ment -;­
`destgn w.s 1n edd:ng d
`l ~ rae c~pdc: t o• 1n p a rell e l
`with the powt>r
`S 1t <?nter~ €'c<Ch
`:O!.tl:•p1v
`transducer's dr1ver . Th 1 • Wc< S done 1n orde r to
`suppl y t h P rat e d 2 00111 mA e.a ch t ransducer needs
`during the 326 • uS tr~nsnoit per1od. Thi~ 1~ ~uch a
`rapp1d dratn that the power supply could not source
`it through 6ft of cabl1ng.
`
`f1
`
`SCEA Ex. 1033 Page 14
`
`

`
`II . THE TONE GENERATOR BLOCK
`
`The tone generator block consists of the
`XR2206 function generator ch1p which is capabale of
`switching between two selPcted tones, and an LM2002
`8 watt audio power ampl1f1er ch1p that amplifies
`the tone s1gnC\l and drives the 8 ohm speaker. <se>e
`fiqure8).
`
`The XR2206 has the abl 1tiy to output a stable
`tone and change to a nothe r
`t one b y switching the
`TTL leve l at the FSK input . Th1s allows sev er al
`types of warnings to be generate d . The t wo tone s
`are seperatly adJusta ble and inde p endent . These
`adjustments a r e made to R4 and R6 in f lgure 8 . The
`potentiometer <R7l in the f igur e is a volume
`adjustme nt allowing t he overall loudness to b e
`changed .
`
`Turn1ng the tone off ~11 togther 1s done w1th
`the Amplitude Modulation 1nput witch 1f held at
`half the supply voltage to the chip will stop the
`output of the tone. What was done here WdS to butld
`a voltage div1der w1th t wo equal res1stances
`therefore a voltage at half the s upply .
`then
`parrallel a 2N3904 to ground. now the base of the
`trans1stor can accept a TTL s1gnal and s w1tch the
`tone on or off,
`
`III . THE ADDITONAL PIA AND TIMER BLOCKS
`
`The interface block necessa tated a s econd 8255
`programable port. It is conf1oured to have 24 bits
`of output and 4 b1ts o~ Input. W1th port A and B
`be1no output ports alono with the h1oher 4 b1ts of
`port C. The lowe>r 4 b1ts of port C are the input
`btts. Port A controls the ultrasonics INITt and
`BLNKI of each transducer. Port B output a d1gitMl
`word to be use by the motor control c1rciuts for
`d1rect1on and speed control. Port C controls
`the
`tone gene rator w1th its upper half and rece1ves the
`ECHO• from theo transducers on the 1 ower half.
`<see
`flgur e 15)
`
`The time base block consists of three
`programmable counterlt1mer~ 1n the 8253 on the
`t
`timer •• configured to count down
`SCCR-R~. Th~ f
`frcJm :,5. 5:;5
`\k:•TTtHf al"'\d 1 s used eos ct 1..to.., wC!tch
`~~·· ll"1C! the r.;ongu g cyCJt:. The second f~•nct1on OT
`the 8~5~ !B gPner?tlon of the lo&baud clock nwedPd
`for R8-232C coroomLonC'cat 1 on. Tt•e 1 ast counter is Lt'!'t?d
`for a heartbeal 1nterupt . This w1ll
`return the
`chair to the joystick conf1guration 1f the computer
`b e comes inopperat1ve or is turned off .
`
`12
`
`SCEA Ex. 1033 Page 15
`
`

`
`GENERAL DISCUSSION
`
`The ultrasonic ~yst em and it parts have all been bread(cid:173)
`boarded and tested. All parts worl as expected, and the ranging
`system . 1n partlcL•lc.r . out performs what was expected of it. The
`ul trason1 c system 1 s very easy to use and 1 s e >:treml y accure<te
`c~nd rel1ab1e . Th~ one dnd only d1sadvantaoe lo ultrasonics as
`opposed to other ranging methods would be the perceivable cl1c~
`when the transducer f 1 res .
`
`From a designers standpoint, using a prebLtilt module fo r the
`units was def1n1tely better than trying t o des1gn the modules
`themselves . This made troubleshooting the modules harder 1f the y
`failed to work <they often did) because of not be1ng exactly sure
`of what the module was tring to do. A lot o f
`t he solut1ons to
`those problems came about from tr 1al and error and a b1t of luck.
`
`The desi gn of the tone generator and additonal PIA/t1mer
`configuration was much more stra1ght forward and the results more
`along the l1nes of whe~t was e>·pected. The onlv problen• e~r1s1no
`here "'as dr1 v1 ng the 8 ohm 1 oad of the spec<l er . After trv1 ng to
`use voltaoe and current amps 1741 and 3900), and transformers and
`push- pull amps, 1t was decided to use the LM2002 wh1ch 1s made
`for suc~1 a purpose.
`
`What is left for these parts 1s for a s1nqle PC board for
`the PIA, tone generator, power supply and motor control c1rcuits
`to be made and tested . The software for the control of these
`circuits has been done to the e>:tent that tes.ting required, but
`has a long way to go before the Easy Chair is completed.
`
`13
`
`SCEA Ex. 1033 Page 16
`
`

`
`THE COMPUTER AND MOTOR CONTROL BLOCKS
`
`SCOPE
`
`The compute~ and motor control systems n~e poss1bly the most
`1mprotant parts of the Easy Chen~ system. A fa1lure 1n e1ther of
`these two svstems could ~ender the ent1re system lnopperative.
`Therefo~e. durabil1tv and usablttY are two maJor conce~ns. The
`computer svstem was chosen due to its ablit1es and because of the
`knowledqe and familiar1ty of the EET staff w1th th1s product. So
`far it has filled the need and lived up to its expectations.
`
`The motor control system 1s the weakest part of the total
`system as 1t stands now. This was due to the l1mited amount of
`t1me spent w1th the wheelchair 1tself. Arrangements have already
`been made to speed a great deal of time on th 1 s port 1 on ne>: t
`semeste~ .
`
`BODY
`
`I . THE C011PUTER BLOCI/
`
`The computer bloc~ 1s made from the 8085 based
`s1nqle card compute~ system avalible from Purdue.
`The computer was built acco~ding to the manual
`p~ovided . After opperation was verified, the
`following changes were made. Clock speed was
`1ncreased to speed execut1on t1me but no
`apprec1able increase has been noted . The memory
`conf1gurat1on for the computer cons1sts of th~ee
`types:
`8K of EPROM for start\.IP sequence and
`monitor, 8K of static RAM fo~ data storage and
`program development, and 2K of EEPROM memory used
`to store the mPnu 1nformat1on and other 'har d'
`vari,.bles. ThE' EEPROM 1s P pected to be conf·ourPd
`to allow anvone to make easy and permanent chances
`1n the menus o~ parameters. (see f1gures 10-16>
`
`II. THE MOTOR CONTROL BLOCV
`
`The motor control blocl. conta1ns all the
`necessary electron1cs to switch control of the
`ch~lr over to the Easy Cha1r controller . When this
`happens , the l1ght pad and ultrason1c systems
`become the controller replacing the Joystick . The
`mote~ control c1rcuit uses a single 2 d1git
`he"adec1mal value to control both motors in
`~PP~~ . Jmately ~Jqht spP•d~ forward, and e1ght
`'"f:",eds ~Pver""• Tlus sho•ua o<llow not only for
`cmooth ~pPed ctoeroaes. but ,lso. start1ng .,rod
`stopp · rg s oOl<l d root bt- roullh or J t-rl ".
`
`Operation of the controller is falrly stralqht
`forward . Two A0558 digital to analog converters are
`used to create a digitally controlled voltage
`
`14
`
`SCEA Ex. 1033 Page 17
`
`

`
`variable from 0-2 volts . This output is summed w1th
`a 7 volt reference to produce an overall output
`controllable from 7 to 9 volts . The joyst1cl pots
`hC\ve been measured to be i't these ootent1al5 dur1ng
`operatton of the cha1r. Although this has not been
`fully
`tested.
`it is bell eved
`to be
`"'
`solmd
`design. <see figure 9)
`
`IS
`
`SCEA Ex. 1033 Page 18
`
`

`
`GENERAL DISCUSSION
`
`The computer system lS worl: ing as e x pected and software
`is the only th1ng planned to be added to 1t at thls t1me . It
`1s e xepected that an add1t1onal EEPROM will be add 1n the
`future to allow greater p r ogram ~lexibility and poss1blv an
`increase 1n the number and qual1ty of the menus. The add1 t ion
`of the extra 8255 caused n o problems with the system and was
`easily added by using the available selects on the computer
`board .
`
`The motor control system is the part of the Easy Chair
`wh1ch the most effort is currently being put forth on. The
`design should wor k theoret1cally, but there are concerns such
`as no1se and dr1ft , which must be addressed ne>:t semester .
`Along with software. motor control is where most efforts will
`be concentrated next semester.
`
`''
`
`SCEA Ex. 1033 Page 19
`
`

`
`CONCLUSION
`
`The proJect as a whole seems to be running very smoothly, 1n
`fact, ahead of schedule. Each of t he separat e blocks 1s
`1ndependantly work1ng, w1th almost all fu nction1ng togethe r as a
`systen •.
`
`As far as software 1s concerned, the or 1g1 nal mon1tor
`program used 1n the SCCS-85 computer h as be e n mod1f1ed to 1n clude
`seve r al small test rou t1nes . These routines currently e x erc1se
`only the seperate b lock s to assure that they are working
`corre c tly.
`
`The des1gners felt that at this point, the software was only
`in an experiment a l stage, a nd that t he more serious software work
`woul d take place during the sec ond semester o f the 1985-86 school
`year at Purdue. For that reas on , this r eport •H•l y 1 nc l•J