TELKOM
NIKA
, Vol.13, No
.2, June 20
15
, pp. 442 ~ 4
5
0
ISSN: 1693-6
930,
accredited
A
by DIKTI, De
cree No: 58/DIK
T
I/Kep/2013
DOI
:
10.12928/TELKOMNIKA.v13i2.1490
442
Re
cei
v
ed
Jan
uary 31, 201
5
;
Revi
sed Ma
rch 2
7
, 2015;
Acce
pted April 12, 2015
Application of Single MEMS-Acceler
ometer to Measure
3-Axis Vibrations and 2-Axis Tilt-Angle Simultaneously
Didik R. San
t
oso
1
*, Sukir
Mar
y
anto
2
, Ahm
a
d
Nad
h
ir
1
1
Divisio
n of Instrumentatio
n, Ph
y
s
ics De
part
m
ent, Bra
w
ij
a
y
a Univ
ersit
y
, M
a
la
ng, Indo
nesi
a
2
Division
of Geophy
sics, Physics Departmen
t, Bra
w
i
j
a
y
a
U
n
iversit
y
, Mal
a
ng, Indo
nesi
a
Jl. Veteran 2 M
a
la
ng 6
514
5, telp. +
62-3
41-
5
758
33, fa
x. +
62-34
1-57
58
34
Corresp
on
din
g
author, e-mai
l
: dieks@
ub.ac.i
d
A
b
st
r
a
ct
This pa
per d
i
sc
usses a
bout a
techni
qu
e to d
e
ve
l
opi
ng a
n
i
n
tegrated s
ens
o
r
system for
measur
ing
mec
h
a
n
ica
l
vi
bratio
ns i
n
3-
axis
and
tilt ang
le in
the 2-axis
si
mu
lta
neo
usly, us
in
g si
ngl
e ME
MS-
accel
e
ro
meter,
i.e. MMA736
1
L
. T
he MMA73
61L
is an
an
al
og acc
e
ler
o
me
ter w
i
th max
i
mum s
ens
itivity
of
800
mV/g. T
h
i
s
device h
a
s 3
-
chan
nels o
u
tp
ut voltage (V
x
, V
y
, V
z
) in res
pons
e to the a
cceler
a
tion "
g
"
of
each ax
is corr
espo
ndi
ng w
o
r
k
(g
x
, g
y
, g
z
). By using cert
ain
techniq
ues i
n
the desi
gn of s
i
gn
al con
d
iti
oni
n
g
circuits, then th
e MMA736
1L c
an us
ed to d
e
tect 3-axis vi
bra
t
ion a
nd 2-
axis
tilt angl
e at th
e sa
me ti
me. T
o
accomm
odate
the 5-signals from
out
put of
the sens
or system
, is c
onstr
ucted a data
ac
quisition system
base
d
o
n
PIC
16F
87
6
micr
o
c
ontrol
l
er, w
h
i
c
h prov
id
es
5-
chan
nels
int
e
rnal A
DC w
i
th
10
bits res
o
lut
i
on
.
Thus, the resu
l
t
ing int
egrate
d
sens
or
syste
m
beco
m
es
very simple an
d
in
e
x
pens
ive. Res
u
lts of exp
e
ri
ment
show that the
devel
oped s
e
nsor system
has prov
en hav
ing good
perfor
m
ance. For the vibr
ation s
e
nsor,
voltag
e gai
ns can be
set up to
60
dB
(8
00 V/g)
w
i
th
lo
w
-
l
e
vel
no
ise. W
h
ile
the ti
lt se
ns
or is
cap
a
b
l
e
o
f
detectin
g
up t
o
± 30 a
n
g
l
e
on the n
on-
lin
earity of 4.5%
(max), w
i
th
a
v
erag
e reso
luti
on of ab
out 0.
06
degr
ees.
Ke
y
w
ords
: Integrate
d
Sens
o
r
, Vibration, T
ilt
-Angl
e, MEMS-Acceler
o
meter
1. Introduc
tion
For analyzi
n
g
the
dyna
mic motion
of an obje
c
t,
the m
easure
m
ent
of multi-axis
vibration
and tilt-a
ngle
often pe
rformed
si
multa
neou
sly. Fo
r example, fo
r testin
g a
n
d
analysi
s
of
the
dynamic m
o
vement of a ship [1], investigating
active volcano [2],[3], determine t
he health
stat
us
of indu
stri
al
machi
n
e
s
[4],
[5], and
so
on
. In he
re, to
g
e
t sim
u
ltane
o
u
s
mea
s
u
r
em
ent of vib
r
atio
ns
and tilt-a
ngle,
will
re
quire
more
then
on
e ki
nd
of sen
s
or.
The
n
m
e
asu
r
ing
in
stru
ment
will b
e
come
compl
e
x and
may be expe
nsive. The
co
mplexity is n
o
t only in terms of the
se
nso
r
de
sig
n
, but
also in the d
a
t
a acqui
sition
(DAQ
) sy
ste
m
.
The me
asure
m
ents of vib
r
ation a
s
well
as
tilt angl
e can be
co
ndu
cted by usi
ng
variou
s
sen
s
o
r
s, of
course e
a
ch of
them with th
eir o
w
n
me
rit
s
an
d limitations. In recent
year, appli
c
a
t
ion
of micro el
ectro-me
ch
ani
cal system
s (MEMS) acce
l
e
rom
e
ter to
detect vibration as
well a
s
tilt-
angle
ha
s b
e
en
widely u
s
ed in va
rio
u
s fields of ap
p
lication,
su
ch
as in [4]-[8].
Accele
romet
e
r
sen
s
o
r
s
mad
e
usi
ng MEM
S
are b
e
tter
than thei
r
co
nventional
co
unterp
a
rt
s be
cau
s
e th
ey a
r
e
smalle
r in si
ze, low p
o
wer con
s
umpti
on, sen
s
itiv
e
to input variations, ea
sy to integrate i
n
to
system
s or m
odify, and ch
eape
r.
No
wad
a
ys, m
any kin
d
s
of MEMS accel
e
rom
e
ter h
a
ve bee
n availa
ble in the
co
mmercia
l
market with
relatively l
o
w-co
st. ME
MS accele
ro
meters play
an imp
o
rta
n
t role i
n
t
he
instrumentati
on of dynam
ically
sensitiv
e system
s.
MEMS ac
cel
e
rom
e
ter has capabilities to
detect vibration a
s
well as tilt-an
g
le
by pr
e
c
isely and a
c
cura
tely. Therefo
r
e, the ide
a
of
integratin
g vibration
sen
s
ors a
nd tilt sen
s
o
r
s into
one modul
e
by using si
ngle chip M
E
MS
ac
cele
rom
e
t
e
r is v
e
ry
int
e
r
e
st
ing t
o
ma
k
e
t
he sen
s
o
r
sy
st
em b
e
co
me simpl
e
an
d low c
o
st
.
2. Rese
arch
Metho
d
2.1. Working
principles of the s
e
nsor
s
y
stem
Figure 1
sho
w
s
a blo
c
k di
agra
m
of the
integr
ate
d
se
nso
r
sy
stem
whi
c
h i
s
deve
l
oped i
n
this research
. The sen
s
o
r
system
ha
s cap
abilit
ie
s to
mea
s
ure of
three co
m
pone
nts (3-a
xis)
vibration
s
an
d two
com
p
o
nents
(2
-axis) tilt-angl
e,
si
multaneo
usly
. The 3
-
axis
vibration
s
a
r
e
in
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
Applic
ation of Single MEMS-Acc
elerometer to Meas
ure 3-A
x
is
Vibrations
... (Didik
R. Santos
o)
443
dire
ction
of (x
, y, z), i.e.
Vib [X]
,
Vib [Y]
,
Vib [Z]
, whil
e
the 2
-
axis tilt-angl
e
a
r
e
in dire
ction of
(x
z)
and (yz), i.e.
Tilt [XZ]
and
Tilt [YZ]
.
Figure 1. Block di
agram of
the develope
d sen
s
o
r
syst
em
‐
2.
00
‐
1.
50
‐
1.
00
‐
0.
50
0.
0
0
0.
5
0
1.
0
0
1.
5
0
2.
0
0
0
6
0
1
2
0
180
240
300
360
St
a
t
i
c
A
cce
l
e
r
a
t
i
o
n
(g
)
Angle
(deg)
Til
t
An
g
l
e
Vs
Sta
t
ic
Accel
e
r
a
t
i
on
Gx
Gz
AT
an(
G
x/G
z
)
(A)
(
B
)
Figure 2. (A)
Static accele
ration voltage
s, (B
) g-val
u
e
as functio
n
o
f
tilt-angle po
sition
In this re
se
a
r
ch,
we u
s
e
an IC MMA7
361L. It i
s
a
n
an
alog
-tria
x
ial ca
pa
citive ba
se
d
MEMS accel
e
rom
e
ter, fab
r
icate
d
by F
r
eescal
e
Semi
con
d
u
c
tor. T
he MMA7
361
L featuri
ng
si
gnal
con
d
itioning, temperature comp
en
satio
n
,
0
g-dete
c
t, and g-sel
e
ct
which allo
ws for the sele
ction
betwe
en
t
w
o sen
s
itivities (±1.5 g
a
nd ±6
g
)
with
sen
s
itivity maximum of
800
m
V
/g @ 1.5
g.
The
device
ca
n
measure bot
h po
sitive a
nd ne
gativ
e mech
ani
cal accele
ration [9].
Principle
of
vibration a
nd
tilt measurem
ent by usin
g MMA7361
L i
s
dete
c
tion “g
” value du
e to dynami
cs a
nd
static a
c
cele
ration. With n
o
me
chani
cal
accele
ration
(g=0), the
M
E
MS output voltage i
s
at m
i
d-
sup
p
ly
(V
DD
/2). For po
sitive accele
ratio
n
, the output will increa
se
above V
DD
/2,
and for ne
gat
ive
accele
ration,
the output
wil
l
decrea
s
e
be
low V
DD
/2. In hori
z
ontal
po
sition a
s
sho
w
n in
Figu
re
2A,
MMA7361
L g
i
ves a certain
voltages o
n
the pin-outs
(X
OUT
, Y
OUT
, Z
OUT
) am
ount
depe
nd
s on t
h
e
positio
n. By the u
s
e
of V
DD
= 3.3
V a
n
d
g-sel
e
ct
=
±1.5g
(sen
siti
vity is set to
800 mV/g
), t
h
e
values of the
MEMS static voltage are 1.
65 V fo
r 0 g, 0.85 V for -1
g, and 2.45 V
for +1 g.
Figure 2B sh
ows relatio
n
ship between
the
angle p
o
s
ition (in d
e
g
r
ee
) and the
static
accele
ration
(in ‘g’) of the
MMA7361
L i
n
the direct
io
ns of x-axi
s
and
z-axi
s
. As sho
w
n in t
h
is
figure, the rel
a
tionship bet
wee
n
tilt angl
e and
static
accele
ration i
s
not line
a
r,
but as the
si
ne
function. Su
ch ch
ara
c
te
rist
ic is n
o
t favorable i
n
term
s of a sen
s
o
r
desi
gn du
e to non
-line
a
rly
.
Actually, to get true line
a
ri
ty on the tilt
angle
m
e
a
s
u
r
eme
n
t by using MEMS a
c
celeromete
r is
requi
re
d two
-
axis. Then,
g-values
cal
c
ul
ated by u
s
ing
arc tan (g
x
/g
z
), as
sh
own
o
n
the g
r
een li
ne
on that figure.
However, for small an
gle, the value of (sin
) will
be almost same with
(arc-tan
),
so the u
s
e of one axis
will not prod
uce too la
rg
e mea
s
ureme
n
t errors
(see Figu
re 2B).
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 2, June 20
15 : 442 – 45
0
444
2.2. Design
of 3-axis Vibrations Sen
s
or
Acco
rdi
ng to
Figure 1, to b
u
ild a 3
-
axis
vibration sen
s
or by
usi
ng MMA7361
L,
we
n
e
e
d
all of the output of
this device, i.e. X
OUT
, Y
OUT
, and Z
OUT
. The
s
e outp
u
ts then be conne
cted to the
sign
al co
nditioning
circuit. Procedu
re to develop t
he
signal conditio
n
ing ci
rcuit is as follo
ws:
First,
remove
static a
c
cel
e
ration
volta
ge of th
e M
M
A7361
L, to
ma
ke
sig
nal
swing
on
th
e
zer
o
-li
ne (0 V
)
,
Secon
d
, filter the sign
al to redu
ce hig
h
freque
ncy noi
se,
Third, amplifi
c
ation the
sig
nal, so it
is in the rang
e of (-2.5 to 2.5) V,
Fourth, lift the sig
nal by 2
.
5 V, to put it on t
he p
o
siti
on in the mi
d
d
le of (0
-5
)
V; it is upon
requ
est of the
DAQ (which will be de
scri
bed later).
Implementati
on of the a
b
o
v
e pro
c
ed
ure
to build
circuit is given i
n
Figure 3. Th
e ci
rcuit
con
s
i
s
ts of low pa
ss filter (LPF
), high
pass f
ilter (HPF), an
d instrum
entation
amplifier (IA
)
.
Functio
n
of
L
P
F is to
red
u
c
e
high f
r
equ
enci
e
s
noi
se,
whe
r
e
a
s HP
F is to
re
move stati
c
volta
ge
(DC) ca
used by
static acceleratio
n
of
t
he
MMA
7
361
L. Then
by a
pplied
HPF, t
he stati
c
volt
age
will removed
automatically. In he
re, bot
h HPF
and
L
P
F are
de
sig
ned b
a
sed
o
n
2
nd
-o
rde
r
(-
20
dB) Sallen
-
Key filter, and built by usin
g IC LF35
3. The LF3
53 is dual Op
-am
p
with low-co
st,
high-sp
eed,
JFET-i
nput
with very lo
w i
nput offs
et voltage. It re
q
u
ire
s
lo
w
su
pply current
yet
maintain
s a l
a
rge
gain
-
ba
ndwi
d
th prod
uct and
a fast
slew
rate [10
]. The corne
r
freque
ncy of
LPF
(
f
C-LPF
) as we
ll as HPF (
f
C-
HPF
) is given by formula in
Eqs.(1
)
and
Eqs.(2
) re
sp
e
c
tively [11].
By
determi
ning values of
(
R
1
, R
2
, C
1
, C
2
) and
(
R
3
, R
4
, C
3
, C
4
),
then the
worki
ng frequ
ency
(freq
uen
cy re
spo
n
se) of the vibr
ation se
nso
r
ca
n be specifie
d.
Furthe
rmo
r
e,
in
vie
w
of DAQ syste
m
,
the
i
n
tern
al ADC
of
the
microcontroll
er nee
ds
analo
g
input
sign
als
within
(0-5) V. To
provide
thi
s
condition,
the output
si
gnal from
the sign
al
con
d
itioning
circuit
sho
u
ld
be in
the
range
of
(-2.
5 to 2.5
)
V,
and th
en b
u
ffered
by 2.5
V.
Therefore, th
e output
sign
als of
the M
M
A7361
L (af
t
er pa
ssi
ng t
he filter ci
rcu
i
ts) ne
ed to
be
amplified several time
s. The value of amplificat
ion (vol
tage gain
)
is depe
nd
s on the power of th
e
mech
ani
cal vibration
whi
c
h
is detected
by the
MMA7361L. In here
,
the voltage
amplifier ci
rcuit
perfo
rmed
by an inst
rume
ntation amplif
ier (IA), a
nd
con
s
tru
c
ted
by IC AD62
0
.
It is low co
st
device
an
d id
eal fo
r u
s
e
in
the
pre
c
i
s
ion
DAQ
sy
stem
s. Th
e A
D
62
0 requi
re
s o
n
ly one
extern
al
resi
sto
r
to se
t voltage gain
s
(Av) of 0 d
B
to
60 dB, even more. Voltage gai
ns
of the AD62
0
is
given by Eqs.(3) [12]. On
ce the si
gnal i
s
already
at t
he de
sired le
vel, it then shifted by 2.5
V,
throug
h the
setting u
p
of
a refe
ren
c
e
voltage (RE
F
) of AD620
. Thus, o
u
tp
ut sign
al of t
he
vibration
sensor
will fluctuate (swing) at the va
lue of 2.5 V. Then the
signal wi
ll has mi
nimum
value of at 0 V and maxim
u
m value of at 5 V.
In addition, Zene
r
Diod
e (5.1 V) mounted o
n
the
IA serve
s
a
s
a safety for th
e DAQ ove
r
v
o
ltage ex
ce
ss of the sig
nal
s. In he
re, to
handl
e of thre
e-
axis vibration
s
se
nsor, we
need three m
odule
s
of sig
nal co
nditioni
ng circuit
s
.
C
2
C
1
U
1
U
2
R
3
R
4
C
3
C
4
R
1
R
2
RG
IN
+
IN
-
RG
OUT
REF
R
G
2.
5V
V
OUT
Z
V
IN
Fr
om
MMA
736
1L
LPF
H
PF
IA
U
3
Figure 3. Signal co
nditioni
ng circuit for
vibration sen
s
or
Hz
C
C
R
R
f
LPF
C
2
1
2
1
2
1
(1)
Hz
C
C
R
R
f
HPF
C
4
3
4
3
2
1
(2)
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
Applic
ation of Single MEMS-Acc
elerometer to Meas
ure 3-A
x
is
Vibrations
... (Didik
R. Santos
o)
445
1
4
.
49
G
v
R
k
A
(3)
2.3. Design
of 2-axis Tilt-angle Sen
s
or
To build a 2-axis tilt-angle
sensor by u
s
ing MMA7
3
61L, we ne
e
d
two sign
al
s of th
e
device, i.e. X
OUT
and Y
OUT
.
In here, Tilt [XZ] related to
the X
OUT
(Vx), and Tilt [YZ] related to the
Y
OUT
(Vy). Th
e pri
n
ci
ple of
tilt measu
r
em
ent by
u
s
ing
MMA7361
L i
s
to utili
ze
st
atic a
c
cele
rat
i
on
voltage d
ue t
o
the
gravitational fiel
ds ‘g’.
Thu
s
,
the
sta
t
ic a
c
cele
ratio
n
voltage
of t
he MMA
736
1
L
is de
pen
ds
o
n
its po
sition
again
s
t the
downward
di
rection
(di
r
e
c
tion of the g
r
a
v
itational field).
Relatio
n
ship betwe
en tilt angle an
d output volt
age o
f
the MMA7361L is given i
n
Figure 4. The
maximum vol
t
age (2.45 V) co
rre
sp
ond t
o
the
static
a
c
celeration of
(+1 g
)
, the
minimum volt
age
(0.85 V)
corre
s
po
nd
s to the (-1 g
)
, and center voltage
(1.65 V)
corre
s
po
nd
s to the (0 g).
Figure 4. Rel
a
tionship bet
wee
n
angle
a
nd output voltage
Figure 5 sho
w
s a capture
d
and normali
zed (ze
r
oi
n
g
) signal
s in the rang
e of (-9
0 to +90)
degree
s. The
additional li
n
e
(g
reen li
ne) on this figu
re obtaine
d from arc-ta
n (Vx/Vz), and it is a
linear lin
e. It
seem
s
clea
r that mea
s
ure
m
ent of
tilt angle by usin
g MMA7361
L will produ
ce lin
ear
voltages whe
n
pe
rformed
by two
-
ax
is sensi
ng.
Ho
we
ver, for th
e
re
aso
n
s of
sim
p
lification
on
the
sen
s
o
r
de
sig
n
, in this p
r
o
j
ect we use
one-axis
d
e
tection
only. As de
scrib
e
d
above, for
small
angle
case, the valu
e of [V
x] is alm
o
st
e
qual to
the va
lue of
arc-ta
n
[Vx/Vz]. For
MMA7361
L
with
sen
s
itivity 800 mV/g, and in the positio
n
like in Figu
re
4, then:
)
sin
*
8
.
0
(
Y
X
V
V
volt;
)
cos
*
8
.
0
(
Z
V
volt
(
4
)
Percentag
e o
f
the maximum non-li
nea
rity can be calculated by:
%
100
*
)
/
(
arctan
*
8
.
0
)
/
(
arctan
*
8
.
0
%
Z
X
Z
X
X
V
V
V
V
V
linearity
non
(5)
By using Eqs.
(5), the p
e
rce
n
tage of maxi
mum
non
-line
a
rity for som
e
small an
gle
can b
e
cal
c
ulate
d
. F
o
r
example
s
,
su
ch
as for 3
0
de
gr
e
e
s
is 4.5%,
20 deg
ree
s
i
s
2.0% and 10 deg
re
es
is 0.5%. Smaller angl
e of measure
m
ent
will pro
d
u
c
e smaller n
on-li
n
earity.
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 2, June 20
15 : 442 – 45
0
446
Figure.5. Normalize
d
tilt-a
ngle vs. outp
u
t voltage
In order to i
m
prove
resol
u
tion of
the t
ilt
sen
s
o
r
, m
easure
m
ent
data
sho
u
ld
be in
the
rang
e of
(0 t
o
5) V. T
e
ch
nically, we n
eed to
amplif
y the sig
nal
by seve
ral ti
mes, a
nd th
en
buffered
sign
al by 2.5 volts. For
ca
se
whe
r
e an
gl
e
of measure
m
ent is in the
rang
e of (-30
to
+30
)
de
grees, the norm
a
lized outp
u
t of the MMA73
61
L is
(-0.4 to 0
.
4) V. Then,
amplificatio
n
of
the sign
als b
y
6.25 times, the voltage become (-
2.5
to 2.5) V. Graph in Fi
gu
re 6 sho
w
s th
e
cal
c
ulatio
n
re
sult fo
r tilt a
n
g
le m
e
a
s
ure
m
ent
with
in
range
of
(-30 t
o
+30
)
d
e
g
r
e
e
s
after
sifted
by
2
.
5
V. T
h
e do
t-
r
e
d
c
i
rc
le
is
da
ta
fr
om th
e
s
e
ns
or
outp
u
t
(
V
x)
, and
b
l
ack
line
is
ar
c-
ta
n o
f
th
e
data. It can be see
n
that the smalle
r ra
n
ge
of angle m
easure
m
ent, the linea
rity will better.
0.
00
0.
50
1.
00
1.
50
2.
00
2.
50
3.
00
3.
50
4.
00
4.
50
5.
00
5.
50
‐
30
‐
20
‐
10
0
1
0
2
0
3
0
Vx+2
.
5
AT
AN
+
2
.5
Figure 6. Line
arity of tilt an
gle within -30
to 30 degre
e
s
Based o
n
the
working p
r
in
ciple
s
of MM
A7361L d
ue to static a
c
cel
e
ration, the d
e
sig
n
of
sign
al co
nditioning for tilt-a
ngle sen
s
or
should b
e
follo
w these step
s.
First, pla
c
e a
high-Z buffer to avoid the loadin
g
effect cau
s
e
d
by vibration sen
s
o
r
,
Secon
d
, filter the sign
al to redu
ce hig
h
freque
ncy noi
se,
Third, no
rmali
z
e the si
gnal,
and amplificat
ion to the ra
nge of (-2.5 to 2.5) V,
Fourth, lift the signal by 2.5
V; to put it
o
n
the positio
n
in the middle
of (0-5
) V.
Implementati
on of the a
b
o
v
e pro
c
ed
ure
s
is
gi
ven in
Figure 7. Fo
rmulation to
calcul
ate
corne
r
frequ
e
n
cy of
the
LP
F is same
wit
h
vibrat
ion circuit
e.g.
Eqs (1). No
rmali
z
ed-offset
(1.6
5
V) an
d
sifted
-
offset
(2.5 V
)
is given
by
an a
d
ju
stable
voltage
reg
u
l
ator, an
d n
o
t expre
s
sed
o
n
this
figure.
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
Applic
ation of Single MEMS-Acc
elerometer to Meas
ure 3-A
x
is
Vibrations
... (Didik
R. Santos
o)
447
Figure 7. Signal co
nditioni
ng circuit for t
ilt-sen
so
r
2.4. Design
of Da
ta
Acq
u
isition (DAQ)
In the desi
gn
of DAQ sy
ste
m
hardwa
r
e, t
he u
s
e of a m
i
cro
c
o
n
troll
e
r
as mai
n
com
pone
nt
is
well
choi
ce
to get
a si
mp
le form
and
lo
w b
udget. T
h
e adva
n
tage
s of u
s
ing
a mi
cro
c
o
n
troll
e
r t
o
build a
DAQ
system a
r
e
small dimen
s
i
ons, p
r
og
ram
m
able, sim
p
l
e
, reliabl
e an
d relatively cheap
[13]. Microco
n
trolle
r al
so
dire
ctly conn
ected
to
the
c
o
mp
u
t
er
(PC
)
w
i
th
ou
t o
r
w
i
th
min
i
mu
m
interface. Th
us, in this
re
sear
ch the
DA
Q system i
s
built based
on
PIC
1
6
F
87
6 mic
r
oc
on
tr
o
l
le
r
,
manufa
c
tured
by Micro
c
h
i
p [14]. The
device
ha
s 5-cha
nnel
s intern
al ADC with
10
bits
resolution. B
y
using a A
DC
referen
c
e
voltage (V
re
f) of 5 V, th
e analo
g
voltage that can
be
conve
r
ted by the ADC is in
the range of
(0-5) V.
Therefore, in the desi
gn of sig
nal co
nditioni
n
g
circuit, the
ou
tput voltage
o
f
the
signal
conditionin
g
m
u
st b
e
at
a v
a
lue
(0
-5) V.
For th
e p
u
rpo
s
e
of interfacin
g to the sensor m
odule, Ch
-1 ADC u
s
ed f
o
r Tilt-[XZ], Ch-2 for Tilt-[Y
Z
], Ch-3 to Vib-
[X], Ch-4 for Vib-[Y], and Ch-5 for Vib-[
Z
].
More
over, communi
catio
n
between
DAQ
m
odule
(mi
c
ro
co
ntroller
unit)
a
nd PC is
arrang
ed by prog
ram p
r
o
c
edure that h
a
s be
en in
st
alled on b
o
th
micro
c
o
n
troll
e
r an
d PC. This
comm
uni
cati
on can be pe
rforme
d
by wi
re
o
r
wirele
ss. Usually, wi
reless
com
m
unication is used
to long
di
stan
ce
mea
s
u
r
em
ent via
radio
telemetr
y
syst
em, and
it
ca
n be
ha
ndle
d
easily
by u
s
in
g
a RF
-tra
nscei
v
er such a
s
YS-C20K. It i
s
lo
w
co
st, and capa
ble t
o
cove
re
d a
r
ound
3
km [
15].
Figure 8 sh
o
w
s h
a
rd
wa
re
of DAQ syste
m
.
A D
C
Figure 8. Block di
agram of
the DAQ mo
dule
3. Results a
nd Analy
s
is
Implementati
on de
sign of t
he se
nsor, si
gnal
conditio
n
ing ci
rcuits,
and DA
Q on
a printe
d
circuit b
oard, given in
Fig
u
re
9. Figu
re
9A
sh
ows
p
hoto of the
d
e
velope
d sen
s
or mod
u
le.
The
sen
s
o
r
modul
e is MMA736
1L, and then
packe
d by acry
lic materi
al. It is nece
s
sa
ry to make n
o
t
easily
sh
aken
and
be
co
me
watertig
ht. In
this figu
re,
fiv
e
pin
s
-out
is
made
up
of th
ree
pin
s
of th
e
accele
ration
sign
als (Vx,
Vy, Vz) a
nd t
w
o
pin
s
for th
e po
we
r
sup
p
ly (G
ND an
d
Vdd
=
+5 V
)
.
The
output of the
sen
s
o
r
mod
u
l
e
is then
con
necte
d to
the
sign
al-con
ditioning
circuit
s
to be forme
d
as
vibration si
gn
als i.e.
Vib-[X
], Vib-[Y], and Vib-[Z], and tilt-angle
sign
als, i.e. Tilt-[XZ] and Tilt-[YZ].
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 2, June 20
15 : 442 – 45
0
448
Acco
rdi
ng to
the explana
tion above, in true-hor
i
z
o
n
tal position
(Fig. 2A) a
nd no dyna
mics
vibration, the outputs of the
five
signals
mentione
d ab
ove is 2.5 V.
Figure 9B sh
ow si
gnal
co
nditioning
an
d DAQ mo
d
u
le. This mod
u
le co
ntain
s
of three
sign
al
conditi
oning
ci
rcuits for
vib
r
ation
se
nsors, two si
gnal
co
n
d
itioning
ci
rcuits for tilt-an
g
le
sen
s
o
r
s,
and
a five analo
g
input chan
nel
s
DAQ to a
c
quire
sig
nal
s
from all
(five)
of the sen
s
ors.
As de
scri
bed
above, th
e
sign
al
con
d
itioning
fo
r vib
r
ation
se
nsor co
ns
i
s
ts of
HPF, LPF
a
n
d
voltage ampl
ifier, wherea
s tilt-
angle sensor ci
rcuits con
s
i
s
ts o
f
Buffer, HPF, and voltage
amplifier. Th
e DAQ
syste
m
built ba
se
d on PIC
16F
876 mi
croco
n
trolle
r, it ha
s capa
bilities to
measure up t
o
five chan
n
e
ls an
alog
si
gnal
s sim
u
lt
a
neou
sly, with
ADC resoluti
on of 10 bit
s
. In
addition, the
DAQ
system
module
conn
ected to
t
he comp
uter (P
C,
as
ha
rd
wa
re controlle
r and
data pro
c
e
ssing) via US
B port. We
used TT
L to USB con
v
erter a
s
interface betwe
en
microcontroll
er and P
C
.
From ME
MS
M
M
A7361
L
SC
for
Til
t
-Angle
Sen
s
or
(A)
(B)
Figure 9. (A)
Senso
r
mod
u
l
e, (B
) Signal
con
d
itioning
and DAQ m
o
dule
Hereafter, to determi
ne pe
rforma
nce of the se
n
s
o
r
, we carrie
d out some
simulati
ons. By
usin
g
circuit i
n
Figu
re
3, a
nd
setting val
ue of
R
1
= R
2
= 220
k
Ω
; C
1
= C
2
= 15
nF
; R
3
= R
4
= 3.3
M
Ω
, and
C
3
=
C
4
=
1 µF,
then
corne
r
frequ
en
cy of the LPF i
s
arou
nd
48.5
Hz, a
nd
co
rn
er
freque
ncy of
the HPF is
a
r
oun
d 0.05
Hz. With thi
s
result, freq
ue
ncy re
sp
on
se
of the vibration
sen
s
o
r
is
(0.0
5 to 48.5)
Hz (Figu
r
e 10A
). This freq
ue
ncy ra
nge i
s
usu
a
lly use
d
on the de
sig
n
o
f
sei
s
mic
sen
s
ors, that very
important in
geophy
si
cs
field. Further,
Figure 1
0
B is simul
a
tion
of
usin
g voltag
e-offset a
nd
gain control to make
se
v
e
ral g
a
ins
of the sign
als.
In this figure,
amplificatio
n of the signal
is optimal; si
gnal ha
s
val
ue of (0-5) V
.
It appears t
hat the sign
a
l
is
buffered to
2.5 V, and then
vibration
sig
nals
will
fluct
uate aroun
d this voltage. If amplified
sig
nal
has m
o
re th
a
n
5.1 V, it will be trun
cate
d by zen
e
r di
ode (Fi
g
u
r
e 1
0
C). In h
e
re,
althoug
h ze
n
e
r
diode
will all
o
w ne
gative
signal a
s
lo
w
a
s
-0.7 V, but i
t
is still in
tole
ran
c
e
and
wil
l
no p
r
o
c
e
s
se
d
by ADC. By usin
g Eqs.(3), to
obtained
gain =
20 dB
(10x)
we u
s
e R
G
app
roxi
mately of 5.5 k
Ω
,
for gain
= 40
dB (100x
) we
use
R
G
= 50
0
Ω
, for gain
= 60 dB (100
0x) we u
s
e
R
G
= 50
Ω
, and so
on. We
can
choo
se the
ap
prop
riate
gai
n, but k
eep i
n
mind th
at the la
rge
r
gai
n will
pro
d
u
c
e the
large
r
noi
se.
In experime
n
ts (Fi
gure 1
1
), the gai
n of 60 dB still
provide
s
noi
se that can
be
tolerated.
For the tilt-a
ngle
sen
s
o
r
(Figure 7), th
e mec
hani
sm
is simil
a
r to
the vibration
sen
s
o
r
,
except it n
o
use
s
the
HP
F. The tilt-an
g
le sen
s
o
r
wi
ll detect
stati
c
a
c
cele
ratio
n
(DC-si
gnal
), and
we
can
not a
pply HPF. To
norm
a
lize th
e sig
nal to
b
e
amplified, i
s
u
s
ed
a refe
ren
c
e voltag
e
of
1.65 V that i
s
given
at the i
n
verting i
nput
IA. Buffe
r Amplifier i
n
thi
s
circuit, ha
s
function
to m
a
ke
high imp
eda
n
c
e inp
u
t. It is neede
d to o
v
erco
me loa
d
i
ng effect ca
use
d
by vibration sensor.
As
descri
bed a
b
o
ve, to measure the tilt-an
g
le in t
he ran
ge (-3
0 to 30) degree
s, which corre
s
po
nds
to (-0.4 to 0.4
)
V, for optimal results
we
set t
he voltag
e gain of 6.25
x and shifted
2.5 V. With this
condition, the signal
will fluctuate
i
n
value (0-5) volt
s.
By using 10
bits ADC, the smallest
angul
ar
can
still be detected by the tilt sensor is:
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
Applic
ation of Single MEMS-Acc
elerometer to Meas
ure 3-A
x
is
Vibrations
... (Didik
R. Santos
o)
449
deg
06
.
0
5
deg
60
*
)
1
2
(
5
10
10
volt
volt
LSB
(6)
1.
00
0
m
H
z
10
.
0
0m
H
z
100
.
0
m
H
z
1.
000
H
z
10
.
0
0 H
z
1
0
0.
00
0 dB
-
1
0.
00 d
B
-
2
0.
00 d
B
-
3
0.
00 d
B
-
4
0.
00 d
B
-
5
0.
00 d
B
-
6
0.
00 d
B
-
7
0.
00 d
B
-
8
0.
00 d
B
0.
00
0
s
1
.
0
00 s
2.
00
0
6.
00
0 V
5.
00
0 V
4.
00
0 V
3.
00
0 V
2.
00
0 V
1.
00
0 V
0.
00
0 V
-
1
.0
00
V
-
2
.0
00
V
0.000 s
1.000
s
2.
0
0
0
6
.
00
0 V
5
.
00
0 V
4
.
00
0 V
3
.
00
0 V
2
.
00
0 V
1
.
00
0 V
0
.
00
0 V
-
1
.0
0
0
V
-
2
.0
0
0
V
(A)
(B)
(C)
Figure10. (A)
Freq
uen
cy re
spo
n
se of the vibr
ation se
n
s
or, (B
) Ampli
f
ication an
d a
dding
DC
offset of 2.5 volts, (C) Tru
n
c
ated
sign
al
Finally,
Figu
re
11 sh
ows the
captured
sig
nal m
e
a
s
ured
by u
s
in
g develo
ped
se
nsor
system. In this Figure, the 3-comp
one
nts vibr
ation si
gnal and 2
-
co
mpone
nts tilt-angle si
gnal
are
measured
si
multaneo
usly
. He
re
app
ea
r, that in
Fig
u
r
e
11A tilt a
n
g
le i
s
in
the
zero
po
sition
b
o
th
for XZ
and
YZ, and
me
ch
anical vibration in
du
ced
in
z-directio
n. In Figu
re
11B,
tilt angle
is e
x
ist
for both XZ a
nd YZ, and
mech
ani
cal vibration in
du
c
ed in z-directi
on. In Figure
11C, tilt angl
e is
exist for YZ b
u
t for XZ is
zero, an
d me
chani
cal vibr
ation ind
u
ced i
n
y-directio
n. Finally in Fig
u
re
11D, tilt angl
e is still exist
for YZ but for XZ is zero, and mech
anical vibrati
on indu
ce
d in x-
dire
ction, the
n
vibration si
gnal will
sw
in
g (vibrate
) around its tilt position.
(A)
(B)
Ti
lt [Y
Z]
Vi
br
ati
on i
n
Y-
di
rec
t
i
o
n
Vi
b [Y]
T
ilt [X
Z]
(C)
(D)
Figure 11. Measure
m
ent o
f
3-axis vibrat
i
ons a
nd 2-axis tilt-angle
si
multaneo
usly
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 2, June 20
15 : 442 – 45
0
450
4. Conclusio
n
In this re
se
arch, a si
mple
and lo
w-co
st
sen
s
o
r
an
d system for inte
grated
mea
s
urem
ent
of 3-axis vib
r
ations a
nd 2
-
axis tilt-angl
e
s
of an obj
ect
has b
een d
e
veloped, u
s
in
g singl
e MEM
S
-
accele
rom
e
te
r. The
sy
ste
m
is
com
p
o
s
ed of tw
o m
o
dule
s
: sen
s
or and
data
acquisitio
n
(DA
Q
).
The se
nsor
module d
e
vel
oped ba
se
d on singl
e chi
p
MEMS accelero
meter, i.e. MMA7361
L. By
usin
g ce
rtain
techniq
u
e
s
in the desi
g
n
of
signal co
nditioning
circuits, the M
M
A7361
L ca
n be
function
ed to
measu
r
e 3
-
axis vibration
s
and 2
-
axis tilt-angle, at the same time. The dat
a
acq
u
isitio
n m
odule i
s
dev
elope
d ba
se
d on PIC1
6F
876 mi
croco
n
trolle
r. The
DAQ mo
dule
has
function to
collect am
ount
of five signa
ls from
sen
s
or mod
u
le, si
multaneo
usly
. To validate the
develop
ed se
nso
r
syste
m
, we have con
ducte
d seve
ral experime
n
ts. The re
sult
s of experime
n
ts
indicate that the system
has capability to measure of
3-axis vi
brati
ons and the
2-
axis tilt-angle,
with go
od a
c
curacy. Fo
r t
he vibratio
n
sen
s
o
r
, voltage gai
ns
ca
n
be set up to
60 dB (800
V/g)
with low l
e
vel noise.
While the tilt sensor is
cap
able
of detecting
up to ± 30 a
ngle on th
e n
on-
linearity of 4.5% (max), wit
h
averag
e re
solution of abo
ut 0.06 degre
e
s.
Ackn
o
w
l
e
dg
ment
The a
u
thors t
han
k to the
Dire
cto
r
ate G
eneral
of
Hig
her Ed
ucatio
n (DIKTI) Re
publi
c
of
Indone
sia, for financi
a
l suppo
rt unde
r "Hibah Pen
e
litian Strategis Na
sio
nal
”, contract n
o
.
023.04.2.4
1
4
989/20
14. Also, thank to
the USAI
D proje
c
t (PGA-200
000
505
3) for partial
ly
s
u
pport.
Referen
ces
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