CURRENT-MODE SINGLETON FUZZY CONTROLLER
I. Ba u one, S. Sánchez Solano, J. L. Hue as
Ins i u o de Mic oelec ónica de Se illa - Cen o Nacional de Mic oelec ónica
A da. Reina Me cedes s/n, (Edi . CICA)
E-41012, Se illa, Spain
3 d. In e na ional Con e ence on Fuzzy Logic, Neu al Ne s and So Compu ing (IIZUKA’94),
pp. 647-648, Iizuka - Japan, Augus 1-7, 1994.
This ma e ial is p esen ed o ensu e imely dissemina ion o schola ly and echnical wo k. Copy igh and all igh s he ein
a e e ained by au ho s o by o he copy igh holde s. All pe sons copying his in o ma ion a e expec ed o adhe e o he e ms
and cons ain s in oked by each au ho ’s copy igh . In mos cases, hese wo ks may no be epos ed wi hou he explici pe -
mission o he copy igh holde .
Abs ac .-- This pape desc ibes he ealiza ion o a
uzzy con olle which implemen s he simpli ied
in e ence mechanism. CMOS analog ci cui s whe e
signals a e ep esen ed as cu en s a e employed.
Howe e , he whole sys em is ex e nally communi-
ca ed h ough ol ages, hus enabling simple in e -
ace wi h con en ional con ol ci cui y.
I. INTRODUCTION
The e icien ealiza ion o mic oelec onic sys ems
o uzzy logic-based con ol applica ions equi es a
ca e ul choice o bo h he in e ence mechanisms and
he ci cui s uc u es which implemen each con olle
block. Among he a ious in e ence me hods, he sin-
gle on o simpli ied me hod is he mos adequa e o
ha dwa e implemen a ion, as well as o e ing enough
eedom in he choice o an eceden s and consequen s
o ensu e e icien con ol. Conce ning ci cui design
me hodologies, cu en -mode echniques a e espe-
cially sui ed o di ec implemen a ion o he basic
uzzy ope a o s. Wo king in cu en -mode, dynamic
ange p oblems can be handled wi h enough lexibili y
and a high-speed ope a ion can be a ained. Ano he
impo an ea u e wo h conside ing is he con olle ’s
compa ibili y wi h exis ing de ices. The elec ical
a iable (ei he ol age o cu en ) ha senso s (ac ua-
o s) p o ide (accep ) imposes a limi a ion o he
design echnique o be chosen. In his sense he p o-
posed con olle wo ks wi h ol ages a inpu and ou -
pu o main ain compa ibili y wi h con en ional
ol age con ol ci cui s. Finally, con olle p og am-
mabili y is essen ial since i limi s he con olle adap -
abili y o sol e di e en con ol p oblems wi hou
demanding complex adjus men p ocedu es.
II. CONTROLLER ARCHITECTURE
The simpli ied in e ence mechanism can be consid-
e ed as a pa icula case o hose which a e p oposed in
[1]. Howe e , i s implemen a ion cos is much less as
can be deduced om Fig. 1. The only building blocks
a e membe ship unc ion gene a ing ci cui s o
desc ibe he an eceden s o he di e en ules, Min o
Max ope a o s o implemen he connec i es be ween
hese an eceden s, and a ule ponde ing block (consis -
ing o a cu en mi o and a di ide ci cui ) o ul ill
he exp ession:
In wha ollows he ealiza ion o each block in Fig.
1 is p esen ed.
A. Membe ship Func ion Ci cui (MFC)
The MFC blocks o Fig. 1 gene a e he membe ship
unc ions o he di e en an eceden s. The o m and
loca ion o hese unc ions a e de e mined by a se ies
o pa ame e s, which allow choosing iangula o ap-
ezoidal unc ions wi h di e en slopes. A ol age o
cu en con e o p o ides he cu en Ixi p opo ional
o he inpu ol age. The g oup o med by he ansis-
o s M1, M2 and he block cN ac s as an absolu e alue
ope a o . The block cP pe o ms he bounded di e -
ence wi h Isa and ixes he slope alue o membe ship
unc ion. The ou pu cu en o he MFC ep esen s he
complemen a y alue o he membe ship le el o he
signal Vin.
Ci cui s based on his echnique a e mo e p ecise
han o he app oxima ions epo ed in li e a u e, since
hey do no depend on a combina ion o wo o h ee
unc ions [2-3]. They a e also mo e e icien ega ding
a ea, powe consump ion, and ope a ion speed. In addi-
ion, p og ammabili y is easily included [4].
B. Mul i-inpu MAX Ci cui
The mul i-inpu MAX ci cui which is shown in
Fig. 1 pe o ms a double unc ion. On one hand,
h ough I e i ixes he maximum membe ship deg ee.
On he o he , i implemen s a connec i e MIN be ween
he ules an eceden s, using he De Mo gan’s law:
Min(Ii) = Max (Ii)= I e - Max(Ii)
The ci cui is a modi ica ion o he p oposal in [5]
and uses only 3n+1 ansis o s, ye achie ing he same
p ecision wi h less a ea and powe consump ion. As
shown in Fig. 1, i consis s o a combina ion o Wilson
cu en mi o s which sha e a diode-connec ed ansis-
o . The Ti ansis o s no only ac as ol age ollowe s
bu also conduc he cu en om a low impedance o a
high impedance node, a oiding cha ge e o s wi hou
addi ional cascode o egula ed s ages [6].
C. Di ide
F om a MOS analog ci cui poin o iew, di ision
has always been a cos ly ope a ion in e ms o ime and
a ea. Consequen ly, many o he epo ed uzzy con-
olle s impose he condi ion ha he denomina o in
exp ession (1) assumes he alue 1, o ecu o he use
o global no maliza ion loops [5, 7] which limi he
yo
Σihici
Σihi
---------------=(1)
Cu en -Mode Single on Fuzzy Con olle
I. Ba u one, S. Sánchez-Solano, J. L. Hue as
Dep . de Elec ónica y Elec omagne ismo,
Facul ad de Física, Uni e sidad de Se illa, SPAIN
in e ence speed o he con olle and implemen an
app oxima ion o exp ession (1).
The s a egy ollowed he e is he use o a simple
con inuous- ime di ide ci cui which accep s cu en s
as inpu s and gi es a ol age as ou pu . Fo his, we ol-
low a a iable ans esis ance echnique. This means
he use o an elemen which allows a ela ion Vo=In⋅R,
wi h a esis ance alue R being con olled by a cu en
Id, so ha Vo=In⋅Va/Id.
The s uc u e o his ci cui is shown in Fig. 1. The
ou ansis o s which o m he a iable ans esis ance
elemen ope a e in he ohmic egion. This allows a
la ge dynamic ange han ha eached wi h squa e-
law s uc u es, and equi es less powe and a ea con-
sump ion ( hei geome ies can be minimal). I also
pe mi s a high equency ope a ion, since his s uc u e
is sel -compensa ed o in insic pa asi ic capaci ances
[9]. Finally, i is also mo e obus o ansis o mis-
ma ching.
III. RESULTS AND CONCLUSIONS
The ope a ion speed o he MFC and MIN/MAX
blocks is es ic ed by he ime in es ed in pe o ming
he bounded di e ence because his in ol es changing
ansis o s om being OFF o conduc . Gene ally,
hese imes a e less han 300 ns. Rega ding he di ide
block, i s dynamics is go e ned by a dominan pole
whose magni ude is p opo ional o he bandwid h o
he ampli ie and he alue o Id (which co esponds o
Σhi). Fo ypical alues, he esponse ime o his block
is also some hund ed nanoseconds. Thus, he p oposed
con olle can each he ange o MFLIPS.
The use o a simpli ied in e ence me hod and he
adequa e choice o he ci cui s which implemen he
di e en ope a o s eases he ha dwa e ealiza ion o
uzzy logic-based con ol sys ems. The main cha ac-
e is ics o he p oposed a chi ec u e a e educed a ea
cos s, high ope a ion capaci y, simple in e ace wi h
con en ional con ol ci cui y, and he possibili y o
include digi al p og amming echniques.
REFERENCES
[1] Chuen Chien Lee, “Fuzzy Logic in Con ol Sys ems:
Fuzzy Logic Con olle ” Pa s I and II, IEEE T ansac ions
on Sys ems, Man and Cybe ne ics, Vol. 20 N. 2 (1990) pp.
404-432.
[2] T. Yamakawa, T. Miki and F. Ueno, “The Design and
Fab ica ion o he Cu en Mode Fuzzy Logic Semi-
Cus om IC in he S anda d CMOS IC Technology”, P oc.
IEEE In . Symp. Mul iple-Valued Logic, May 1985, pp.
76-82
[3] T. Ke ne , C. Hei e and K. Schumache , "Analog CMOS
Realiza ion o Fuzzy Logic Membe ship Func ions", IEEE
T ans., July 1993, SC- 28, ( 7), pp. 857-861.
[4] J. L. Hue as, S. Sánchez-Solano, A. Ba iga and I.
Ba u one, “Se ial A chi ec u e Fo Fuzzy Con olle s:
Ha dwa e Implemen a ion Using Analog/ Digi al VLSI
Techniques”, 2nd. In . Con . on Fuzzy Logic and Neu al
Ne wo ks, Iizuka, 1992, pp. 535-538.
[5] M. Sasaki, N. Ishikawa, F. Ueno and T. Inoue, “Cu en
Mode Analog Fuzzy Ha dwa e wi h Vol age Inpu
In e ace and No maliza ion Locked Loop”. IEICE T ans.
Fundamen als, Vol. E75-A (6), June 1992, pp. 650-654.
[6] I. Ba u one, J. L. Hue as, A. Ba iga and S. Sánchez-
Solano, "Cu en -Mode Mul iple-Inpu Maximum Ci -
cui ", Elec onics Le e s, Vol. 30 (9), Ap il 1994, pp. 678-
680.
[7] T. Yamakawa, “A Fuzzy In e ence Engine in Nonlinea
Analog Mode and i s Applica ion o a Fuzzy Logic
Con ol”, IEEE T ans. on Neu al Ne wo ks, Vol. 4, No. 3,
pp. 496-522, May 1993.
[8] M. Ismail, “Fou -T ansis o Con inuous-Time MOS
T ansconduc o ”, Elec onics Le e s, Vol. 23, pp. 1099-
1100, Sep . 1987.
(2)
Ix1 Vbn cP
1 : mx1
Vbp
cN
Fig. 1.- Schema ic o he p oposed con olle .
cN
1o
c1h1
h1
o he ules
consequen
Vx1 V-I
I-V
MFC
Ix2 Vbn cP
1 : mx1
Vbp
cN
Vx2 V-I
MFC
I e
MAX
DIVIDER
:1 :c1