
Abs ac —This pape p esen s he main design s eps in he
de elopmen o an ac i e knee-ankle- oo o hosis (KAFO)
concei ed o assis he gai o incomple e spinal co d inju ed
(SCI) subjec s. The design app oach is based on he idea o
modi ying he a ailable passi e o hoses by adding
adap able mecha onic modules a he join s. This app oach
has esul ed in a p o o ype ha has been es ed on SCI
pa ien s. The design and con ol p oblems ound and hei
adop ed solu ions a e ho oughly desc ibed.
I. INTRODUCTION
HE design o powe ed o hoses and exoskele ons ha
assis human gai is an open ield o esea ch ha co e s
se e al a eas such as biomechanics, mechanical design,
obo ics and neu o ehabili a ion. Those ac i e de ices a e
designed o help pa ien s wi h disabili ies, caused o
example by a spinal co d inju y (SCI) o acqui ed b ain
damage, and ha e shown o be use ul o eco e ing
locomo o unc ion a e he inju y [1], and o a ou ing
physical ac i i y la e , hus imp o ing he pa ien s’ heal h
and quali y o li e a e ehabili a ion.
In he las yea s, a numbe o obo ic de ices aimed a
assis ing human gai ha e been de eloped [2]. The objec i e
o his wo k is o p esen he p og ess o an ongoing p ojec
aimed a designing a pa ien - ailo ed ac i e o hosis o assis
he gai o incomple e SCI subjec s. A pai o o hoses ha e
been buil so a and hey a e now being es ed on pa ien s o
he SCI Uni o he “Complejo Hospi ala io Uni e si a io de
A Co uña” (CHUAC).
The design o he o hosis is based on he ideas o he
Head o he SCI Uni o he CHUAC, who wan ed o
imp o e he comme cial passi e o hoses ha SCI pa ien s
o his uni a e using a p esen . I mus be no ed ha he
a ge pa ien s a e able o con ol hip lexo muscles, being
classi ied unde le els C o D in he ASIA impai men scale
(AIS). The cu en comme cial o hoses include wo basic
pa s: a) a knee locking sys em, which is essen ial o bea he
pa ien ’s weigh du ing he s ance phase due o he lack o
This wo k has been suppo ed by he Spanish Minis y o Economy and
Compe i i eness unde p ojec s DPI2009-13438-C03 and DPI2012-38331-
C03, co inanced by he Eu opean Union h ough EFRD.
J.M. Fon -Llagunes and D. Clos a e wi h he Depa men o Mechanical
Enginee ing and he Biomedical Enginee ing Resea ch Cen e o he
Technical Uni e si y o Ca alonia, Ba celona, Spain (e-mail:
[email p o ec ed]).
F. Rome o and F.J. Alonso a e wi h he Depa men o Mechanical,
Ene ge ics and Ma e ials Enginee ing o he Uni e si y o Ex emadu a,
Spain.
U. Lug ís and J. Cuad ado a e wi h he Labo a o y o Mechanical
Enginee ing o he Uni e si y o La Co uña, Spain.
o ce a he quad iceps muscle; and b) a passi e ankle join
(klenzak join ) ha cons ains ankle plan a lexion du ing
he swing phase, hus a oiding d op- oo gai . Comme cial
knee-locking sys ems a e shape o ic ion-based, being
ac i a ed upon heel s ike de ec ion, usually by means o an
on-o con ac senso . The klenzak join consis s o a sp ing
ha applies an ex e nal do si lexion o que. Those de ices
a e essen ially passi e, being he only semi-ac i e sys em
ha o med by he knee locking mechanism and he on-o
con ac senso .
Those cu en o hoses ep esen he s a ing poin o he
p o o ypes ha ha e been de eloped in he p ojec . Wi h he
aim o ob aining a pa ien - ailo ed, low-cos and low-weigh
p oduc , ou design app oach is based on using as much as
possible he exis ing o hopaedic de ices and de eloping
mecha onic modules ha can be a ached o hem.
The ollowing sec ion p esen s he mechanical design and
senso s o he buil ac i e o hoses, highligh ing he design
p oblems ound and solu ions adop ed. Finally, he main
u u e de elopmen s o he p ojec a e ou lined.
II. MECHANICAL DESIGN AND SENSORS
The main modi ica ions o he cu en de ices sugges ed
by he medical s a o he SCI Uni a CHUAC we e he
ollowing ones: a) in oducing, besides he locking sys em,
ac ua ion a he knee join because he conside ed subjec s
do no ha e enough muscle o ce o lex and ex end he
lowe limb du ing he swing phase; and b) including some
addi ional senso s on he p o o ype o he body in o de o
be e con ol he knee-locking sys em and ac ua ion.
Fig. 1. CAD design o he i s p o o ype o ac i e KAFO.
Mo o g oup
Knee-locking
de ice
Klenzak and
encode
Design o a Pa ien -Tailo ed Ac i e Knee-Ankle-Foo O hosis o
Assis he Gai o Spinal Co d Inju ed Subjec s
J. M. Fon -Llagunes, U. Lug ís, F. Rome o, D. Clos, F.J. Alonso, and J. Cuad ado
T
Based on ha , a i s knee-ankle- oo o hosis (KAFO)
p o o ype was designed [3], Fig. 1. In his p o o ype, a
s anda d klenzak join was sligh ly modi ied including an
op ical inc emen al encode o con ol pu poses. The knee
join inco po a ed wo powe ed sys ems ac ing in pa allel. In
o de o lock he knee du ing s ance, he con ollable shape-
locking mechanism Neu o T onic, manu ac u ed by Fio &
Gen z (Ge many), was used. An on-o con ac -de ec ion
senso p o ided by he company con olled his sys em.
Rega ding he knee ac ua ion, an elec ical EC 45 la mo o ,
manu ac u ed by Maxon Mo o (Swi ze land), oge he wi h
a 1:156 plane a y gea box was used. The mo o included an
op ical encode o i s posi ion con ol. The objec i e o
using he wo sys ems was o a oid he use o he mo o o
locking he knee du ing s ance, hus educing he powe
consump ion o he o hosis. Rega ding he con ol, apa
om he men ioned senso s, a hip elec o-goniome e was
also included. Since he a ge pa ien s a e able o con ol (up
o a ce ain deg ee) he hip join o a ion, his angula
measu emen was in ended o be used as a e e ence o he
knee lexion-ex ension ac ua ion du ing swing. I mus be
men ioned ha his p o o ype had leng h-adap able la e al
ba s, so ha i could be used wi h di e en SCI subjec s.
Fig. 2. (a) P o o ype wi h emu -aligned mo o . (b) Expe imen al es
o a SCI subjec wea ing he ac i e KAFO.
Labo a o y es ing e ealed se e al d awbacks o he i s
p o o ype, which a e desc ibed in wha ollows.
A i s incon enien was ela ed o he ho izon al
a angemen o he mo o axis, which could collide wi h he
c u ches du ing walking. This was amended using a 1:1
be el gea and placing he mo o axis pa allel o he emu ,
Fig. 2(a). Howe e , he lack o obus ness o he gea se
o ced o e u n o he o iginal ho izon al layou .
Rega ding he shape-locking mechanism, a conside able
ex ension o que om he mo o was equi ed o unlock he
join in o de o s a he swing, hus inc easing he powe
consump ion and ime o esponse. So i was decided o use
he mo o o lock he knee, since i p o ed o be capable o
locking ha join du ing s ance.
In wha e e s o he oo -g ound con ac de ec ion, he on-
o ansduce s we e e y un eliable, so hey we e eplaced
by con inuous o ce-sensing esis o s.
Finally, he inabili y o p ope ly measu ing he hip angle
by means o elec o-goniome e s led o disca d i as a con ol
inpu .
The men ioned imp o emen s led o a second p o o ype,
illus a ed in Fig. 2(b), his ime speci ically ailo ed o he
a ge emale pa ien , since he p e ious adap able design
showed o be p oblema ic due o he wide ange o
mo phologies ound among pa ien s. Each o hosis weigh s
less han 2 kg, which was he ini ial speci ica ion o he
medical s a . A PID con olle is used o con ol he posi ion
o he knee ac ua o as a unc ion o he ankle angle o he
con ala e al leg. A eal- ime GUI has been de eloped in
o de o pa ame ically une his unc ion du ing he es s, so
ha i adap s o he gai s yle o he pa ien . Acco ding o he
physicians, his con ol has yielded a mo e na u al gai
pa e n o he SCI subjec , who has been so a walking wi h
he aid o pa allel ba s.
III. FUTURE DEVELOPMENTS AND CHALLENGES
The e a e s ill se e al challenges o ace in he p ojec .
Fi s o all, o he pa ien o be able o walk long dis ances
so ha he pe o mance can be objec i ely measu ed,
po abili y o he sys em is being add essed. The objec i e is
o in eg a e powe and con ol de ices inside a 2 kg
backpack ca ied by he pa ien . As o he mechanical
design, a no el ac ua ion sys em is unde de elopmen and
he use o se ies elas ic sys ems o educe ene gy
consump ion is being in es iga ed. Mo eo e , he use o
elec omyog aphy (EMG) o ac i e muscles o con ol, and
he use o unc ional elec ical s imula ion (FES) oge he
wi h he cu en ac ua ion (hyb id ac i e o hosis) a e also
being explo ed.
IV. CONCLUSION
This ex ended abs ac p esen s he wo k being done in a
p ojec aimed a designing an a o dable and pa ien - ailo ed
ac i e o hosis o gai ehabili a ion o SCI subjec s. The
main ea u es o he p o o ypes and he decisions made
du ing he design s age, which a e based on p ac ical
expe ience on ac ual SCI pa ien s, a e ou lined. F om his
expe ience, se e al design and con ol challenges a e
cu en ly aced in o de o ob ain a p oduc ha could be
in oduced in hospi als and ehabili a ion cen e s.
REFERENCES
[1] M. Hubli, and V. Die z, “The physiological basis o neu o ehabili-
a ion – locomo o aining a e spinal co d inju y,” J. Neu oeng.
Rehabil., ol. 10:5, Jan. 2013, pp. 1–8.
[2] A.M. Dolla , and H. He , “Lowe ex emi y exoskele ons and ac i e
o hoses: challenges and s a e-o - he-a ,” IEEE T. Robo ., ol 24:1,
Feb. 2008, pp. 1–15.
[3] J.M. Fon -Llagunes, R. Pàmies-Vilà, J. Alonso, and U. Lug ís,
“Simula ion and design o an ac i e o hosis o an incomple e spinal
co d inju ed subjec ,” P oc. IUTAM, ol. 2, Jun. 2011, pp. 68–81.