Mobile In e ace o a Sma Wheelchai
Julio Abascal1, Daniel Cagigas2, Nes o Ga ay1, and Luis Ga deazabal1
1 Labo a o y o Human-Compu e In e ac ion o Special Needs
In o ma ika Fakul a ea. Euskal He iko Unibe si a ea.
Manuel La dizabal 1. E-20018 Donos ia, Spain
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2 G oup o Robo ics and Rehabili a ion Technology
E. T. S. Ingenie ía In o má ica. Uni e sidad de Se illa.
A enida Reina Me cedes s/n. Se illa, Spain
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Abs ac . Sma wheelchai s a e designed o se e ely mo o impai ed people
ha ha e di icul ies o d i e s anda d -manual o elec ic powe ed-
wheelchai s. Thei goal is o au oma e d i ing asks as much as possible in
o de o minimize use in e en ion. Ne e heless, human in ol emen is s ill
necessa y o main ain high le el ask con ol. The e o e in he in e ace design
i is necessa y o ake in o accoun he es ic ions imposed by he sys em
(mobile and small), by he ype o use s (people wi h se e e mo o es ic ions)
and by he ask ( o selec a des ina ion among a numbe o choices in a
s uc u ed en i onmen ). This pape desc ibes he s uc u e o an adap i e
mobile in e ace o sma wheelchai s ha is d i en by he con ex .
1 In oduc ion
Sma wheelchai s a e designed o imp o e he mobili y o use s wi h se e e mo o
impai men s ha expe imen di icul ies o d i e adi ional elec ic-powe ed
wheelchai s. The echniques used o au oma ically d i e wheelchai s come om he
Mobile Robo ics and he Au oma ed Guided Vehicles ields [1]. Sma wheelchai s
a e usually p o ided wi h a numbe o senso s and he necessa y so wa e o con ol,
o be able o au oma ically ollow a pa h om a s a ing posi ion o a des ina ion
wi hou human in e en ion [2, 3, 4]. E en i he use o a sma wheelchai does no
need o ca e ully d i e i , he o she mus be p o ided wi h an adequa e in e ace o be
able o gi e he necessa y o de s o he wheelchai con ol.
The design o an in e ace o a sma wheelchai aces di e se p oblems due o he
special cha ac e is ics o he use , he sys em and he ask. Sma wheelchai ypical
use s a e se e ely mo o –and some imes oice– impai ed people ha can no handle
a s anda d in e ace. On he o he hand, he compu ing capaci y o he sys em is
condi ioned by he ac ha usually i is un by an embedded compu e mainly
de o ed o eal ime con ol o he ehicle. In addi ion, people wi h disabili ies need
equen ly di e se de ices ha assis hem o e e yday asks. Ne e heless, hey can
no easily swi ch om a de ice o o he . The e o e, all hese de ices end o be
in eg a ed oge he sha ing an in e ace ha gi es access o all he unc ions equi ed
by he use : wheelchai mo emen con ol, en i onmen al con ol (usually h ough a
domo ic sys em) and, equen ly, pe sonal di ec o emo e communica ion ia
compu e . Among he di e se asks ha he use can pe o m o m ha in e ace, in
his pape we will only analyse he con ol o he wheelchai mo emen , because
communica ion and en i onmen al con ol a e well documen ed [5]. The e o e, he
main in e ace design p oblem is o gi e he use he possibili y o selec a des ina ion
among a ela i ely la ge numbe o choices equi ing he minimum e o . Nex
sec ion p esen s he p ojec we e his in e ace was de eloped.
2 The Te aNau a Sys em
Te aNau a1 p ojec de eloped a con olle o s anda d elec ic-powe ed wheelchai s
ha allows use s wi h e y se e e mobili y es ic ions (such as people wi h
quad iplegia) o easily na iga e in closed s uc u ed en i onmen s (home, hospi al,
school, e c.). The main goal o his p ojec was o design a non-expensi e au oma ic
d i ing sys em o help his kind o use s o employ he wheelchai wi h he minimum
e o , bu main aining he use as ac i e as possible – o bene i his o he
ehabili a ion. Fo his eason he design o an adequa e adap i e mobile use in e ace
was a key ac o in Te aNau a a chi ec u e.
commands
s a us
nex
mo emen
Absolu e
posi ion
Powe
con ol
commands
eedback
es ic ions
pa h signals
s a us
eedback
Use
commands
es ic ions
pa h e en s
p og amming
p og amming
Te aNau a
Sys em
Use
In e ace Pa h
Planne T ajec o y
Followe
Powe
S age
Con olle
Ex e nal
Signals
M
anage
T a ic
Module
USER
Cen al
T a ic
Con olle
Senso s
Mo o s
IR
US
Bumpe ansponde s
Video
came a
Fig. 1. A chi ec u e o he Te aNau a Sys em
F om he poin o iew o he na iga ion, wo main sec ions can be dis inguished in
Te aNau a a chi ec u e ( ig.1), he Con ol Sec ion and he Use In e ace. The i s
deals wi h au oma ic ope a ions -such as signals handling, con ol o he mo o s, e c.-
while he second manages use dialogue. Due o al eady men ioned use mo o
es ic ions, many ope a ions ha usually a e done by he use , mus be ans e ed o
he au oma ic con olle , he eby dec easing he e o made by him o he . Hence,
modules o pa h planning and guidance mus be added. The pa h planning sub-
1 Te aNau a is a esea ch p ojec de eloped by he Na ional Hospi al o Pa aplegics;
Bioingenie ía A agonesa S. A.; he G oup o Robo ics and Rehabili a ion Technology o he
Uni e si y o Se ille and he Labo a o y o HCI o Special Needs o he Uni e si y o he
Basque Coun y.
sys em inds a pa h ee o obs acles be ween wo poin s on a opological map (a
g aph, see ig 2), whils he guidance sub-sys em d i es he wheelchai along he
ajec o y calcula ed by he pa h planning module while es ima ing i s absolu e
posi ion. The pa h planne is implemen ed by means o a sea ch algo i hm ha inds a
pa h ha links wo nodes o a g aph. A de ailed desc ip ion o ha algo i hm can be
ound in [6, 7].
A numbe o beacons a e dissemina ed in he en i onmen o allow absolu e
posi ioning. When he wheelchai app oaches one o hem i ecalib a es i s posi ion.
The e is a command o au oma ically ind a ack o beacon o acqui e he cu en
posi ion when i is unknown by he sys em. I is also possible o manually d i e he
wheelchai o a ack o beacon.
3 In e ace S uc u e
The use con ols he sys em h ough a e y in ui i e g aphical in e ace ha
ansla es his o he o de s (e.g. he desi ed des ina ion) in o commands o he
T ajec o y Planne ( ha calcula es a quasi-op imal ajec o y). I also gi es eed-back
o he use abou he cu en ope a ion.
The inpu de ice o Te aNau a in e ace is ypically he same used o d i e he
wheelchai : a joys ick, mou h-s ick, o any o he al e na i e inpu sys em used in
Assis i e Technology [5]. The ou pu is a small colou display ( ha cu en ly has
been po ed o a PDA). Due o he use mo o es ic ions he selec ion o he desi ed
command is usually done ei he by scanning a ma ix o icons and selec ing hem
wi h a pushbu on; o by means o di ec ed scanning whe e he use goes h ough he
ma ix using a joys ick2.
2 Depending on he use cha ac e is ics o he inpu /ou pu de ices a e possible: o inpu
pu poses ouch-sc eens, oice ecogni ion, e c., while, besides a display, syn he ic oice can
be used o ou pu in some cases. He e we only p esen he mos common choice.
R0 R1 R3 R5
R7
R9 R1 R13
R2 R4 R6
R8
R10 R12
R24 R22 R20
R18
R16 R14
R17 R15
R21 R19
R25 R23
Gymnasium
TV oom
Chapel
Co ee shop
Toile S a Li
Li
O ice Toile
Main en ance
Fig. 2. A g aph (do ed lines) ep esen ing a plan .
Simpli ied Task Model
Fo na iga ion pu poses he use can pe o m he ollowing asks (see ig. 3): when
he ehicle is s opped, i he cu en posi ion is no known by he sys em, he use can
au oma ically ind a ack (o manually d i e he wheelchai o a ack). I he cu en
posi ion is known by he sys em, he use can selec a des ina ion o go o a gi en
des ina ion ( om he cu en localiza ion). While he wheelchai is going o a
des ina ion, he use can change he cu en des ina ion (which s ops he wheelchai
and pass o “selec a des ina ion”). In addi ion, he use can always swi ch o manual
con ol ha s ops he wheelchai and lea es he con ol o a human).
Fig. 3. Simpli ied ask diag am
As i is sown p e iously, mos o he asks can be ep esen ed by icons in a simple
in e ace. Ne e heless, when he use has o selec a des ina ion, he numbe o nodes
in a g aph ep esen ing a s uc u ed closed en i onmen (see ig. 2) is usually oo
la ge o he display moun ed in he wheelchai , making he selec ion di icul . To
a oid his ouble, he in e ace makes use o he in o ma ion he sys em has abou he
ask ha i is pe o ming [8]: he cu en posi ion and he map o possible des ina ions.
The e o e, he same da a s uc u e (a mul i-laye ed map) used o ajec o y planning
is used o display pu pose, due o he in o ma ion managemen acili ies ha i
p o ides. In ac , he hie a chical map model is e y sui able o compac menu-based
displays (do no o ge ha ou implemen a ion o menus is based on scanning and
selec ion). The e o e, each abs ac ion le el can be included in a menu and a selec ion
may be ca ied using a small numbe o menus.
In addi ion, use adap a ion allows he op imiza ion o he choices. When he use
is choosing a des ina ion, he selec ion se is composed only by he eachable
des ina ions om ha poin , o de ed by equency o use. In his way, only possible
des ina ions -in o de o p obabili y- a e o e ed, minimizing he selec ion e o .
O he impo an cha ac e is ic o Te aNau a in e ace is ha i is no in usi e. The
sys em does no ake decisions when he use is able o ake i , which is e y
impo an o acili a e he use ehabili a ion p ocess. Since he abili ies o he use
can change wi h he aining i is necessa y o build an inc emen al use model, o be
able o de e mine wha decisions a e in he hands o he use .
Mo e de ails abou he Te aNau a in e ace can be ound in [9].
Selec
des ina ion
Go o
des ina ion
Change
des ina ion
S a
Find a ack cu en
posi ion
known?
no
yes going o a
des ina ion?
yes
no
Swi ch o manual con ol
4 Conclusion
The design o an adap able mobile in e ace o a sma wheelchai hea ily depends
on he asks ha his de ice pe o ms. The knowledge ha he sys em has abou he
cu en posi ion and he poin s ha a e eachable om his poin allows he design o
a simple and e ec i e in e ace ha akes in o accoun he con ex . The in e ace o
Te aNau a sys em is also adap able and accessible o se e ely mo o impai ed
people. In addi ion, i helps o he ehabili a ion o he use gi ing o he use as much
decisions as he o she can ake.
Acknowledgmen s
This wo k has been pa ially suppo ed by he Spanish Comisión In e minis e ial de
Ciencia y Tecnología (CICYT) -con ac TER96-2056-C02-02- and he Minis e io de
T abajo y Asun os Sociales.
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Engin. Vol. 4, No. 1, (1996)
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g andes pa a obo s mó iles y sis emas AGV. Ph. D. disse a ion (in Spanish). The
Uni e si y o he Basque Coun y. Donos ia, Spain. (2001)
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En i onmen s. Aus ian Jou nal o A i icial In elligence (ÖGAI) (2001)
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