Recei ed May 7, 2021, accep ed June 26, 2021, da e o publica ion July 6, 2021, da e o cu en e sion July 19, 2021.
Digi al Objec Iden i ie 10.1109/ACCESS.2021.3095219
Fibe -Op ic B agg Sys em o he Dynamic
Weighing o Municipal Was e: A Pilo S udy
MARCEL FAJKUS 1, JAN NEDOMA 1, (Membe , IEEE), RADEK MARTINEK 2, (Membe , IEEE),
LUKAS DANYS 2, MICHAEL FRIDRICH 1, PAVEL MEC3, AND STANISLAV ZABKA1
1Depa men o Telecommunica ions, Facul y o Elec ical Enginee ing and Compu e Science, VSB—Technical Uni e si y o Os a a, 70833 Os a a, Czech
Republic
2Depa men o Cybe ne ics and Biomedical Enginee ing, Facul y o Elec ical Enginee ing and Compu e Science, VSB—Technical Uni e si y o Os a a,
70833 Os a a, Czech Republic
3Depa men o Building Ma e ials and Diagnos ics o S uc u es, Facul y o Ci il Enginee ing, VSB—Technical Uni e si y o Os a a, 70833 Os a a, Czech
Republic
Co esponding au ho : Ma cel Fajkus (ma cel. ajkus@ sb.cz)
This wo k was suppo ed in pa by he Eu opean Regional De elopmen Fund in Resea ch Pla o m ocused on Indus y 4.0 and Robo ics
in Os a a unde P ojec CZ.02.1.01/0.0/0.0/17_049/0008425 wi hin he Ope a ional P og amme Resea ch, De elopmen , and Educa ion,
and in pa by he Minis y o Educa ion o he Czech Republic unde P ojec SP2021/32 and P ojec SP2021/45.
ABSTRACT The publica ion ocus on a pilo s udy (design, implemen a ion and e i ica ion) o a dynamic
weighing sys em designed o weighing o municipal was e du ing he dumping o ga bage con aine s.
The p esen ed solu ion is based on ibe B agg g a ings (FBG) and can be addi ionally implemen ed in o
he li ing equipmen o commonly employed ga bage ucks. The weighing p inciple is based on he
measu emen o de o ma ion e ec and ib a ion esponse o he li ing equipmen du ing he dumping
o ga bage bins. The measu ing sys em le e ages he ad an ages o powe measu emen , which use he
con e sion o he spec al shi o modula ed ligh signal du ing he measu emen o he change in op ical
powe o a pai o spec al o e lapping B agg g a ings. Two di e en me hods a e p esen ed and discussed:
he ampli ude me hod, which analyze he maximum ampli ude change o he signal and/o he me hod, which
analyze he ime pe iod o he dampened oscilla ion o he li ing de ice. Due o he small dimensions,
he comple e sys em can be ins alled oge he wi h FBG senso s di ec ly on o he li ing de ice. The pilo
es s o he p esen ed sys em we e ca ied ou o o e 4 mon hs, showing an accu acy o up o ±4.04 kg in he
ange o 10-100 kg o s anda dized con aine s used o municipal was e. The sys em wo ked in comple ely
s andalone mode and he ga bage ucks we e no modi ied in any incon enien way.
INDEX TERMS Fibe B agg g a ing, op ical senso , dynamic weighing.
I. INTRODUCTION AND STATE-OF-THE-ART
Dynamic was e weighing o e s a solu ion o a i ica ion
o ci izens based on he amoun o p oduced was e. This
ad an age is o e lapping – he de ailed o e iew o ga bage
con aine s (including he in o ma ion ega ding hei used o
ee capaci y) can be used by smalle ci ies o municipali ies
o educe was e disposal cos s and addi ional ees. The whole
was e disposal p ocess can also be op imized in e nally o
ex e nally, based on ga he ed da a and beha io o ci izens.
These majo ad an ages a e behind he inc easing deploy-
men o dynamic weighing sys ems. RFID sys ems, which
use inac i e plas ic chips placed on was e bins, can be used o
ansmi he equi ed in o ma ion [1]–[4]. When he ga bage
The associa e edi o coo dina ing he e iew o his manusc ip and
app o ing i o publica ion was Sal a o e Su do .
uck is equipped wi h a weighing sys em, an in o ma ion on
he commodi y and weigh o he was e can be di ec ly ans-
mi ed, hus iden i ying, and cha ging he speci ic ci izen. The
da a is usually s o ed in a cen alized da abase and e alua ed
by a con ol node.
The con en ional app oaches o measu ing ehicle
weigh , o dynamic weighing espec i ely, a e nowadays
di ided in o wo p e e ed di ec ions o de elopmen : Weigh-
In-Mo ion (WIM) and On-Boa d Weighing (OBW). WIM
sys ems a e independen and ex e nal, while he OBW sys-
ems a e buil in o he ehicle i sel . WIM echnology is
usually used o measu e he axle load o ehicle du ing i s
mo emen in combina ion wi h induc ion loops [5]–[7]. The
deploymen o ibe op ic sys ems o dynamic weighing
while d i ing based on a ious p inciples is u he desc ibed
in publica ions [8]–[17]. Fo example, Malla e al. [8]
99050 This wo k is licensed unde a C ea i e Commons A ibu ion 4.0 License. Fo mo e in o ma ion, see h ps://c ea i ecommons.o g/licenses/by/4.0/ VOLUME 9, 2021
M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
p esen s in e es ing expe imen al esul s om a measu emen
on a special op ical ibe o measu e wheel loads o ehi-
cles. The ibe used has a unique design wi h wo concen-
ic ligh -guiding egions o di e en e ec i e op ical pa h
leng hs, which has he po en ial o enable di ec measu emen
o magni udes as well as loca ions o o ces ac ing a mul iple
poin s along a single ibe . In gene al, hese sys ems a e
cha ac e ized by an e o a e o up o ±10 %.
The so-called OBW sys ems, which a e ins alled di ec ly
on he ehicle can be a much mo e in e es ing subjec .
The common goal o he s udies men ioned below is o
design ligh weigh senso s and sys em, wi h high accu-
acy ha can be easily ins alled in o he exis ing ehicles
(ei he di ec ly om he ac o y o e o i ed). The a i-
cle [18] desc ibes a capaci i e lexible senso , whose dynamic
beha io was desc ibed using he Maxwell-Kel in model.
The esul s showed ha he measu emen e o is less han
±10 %. Khei alla e al. [19] deal wi h he de elopmen o
an on-boa d weighing solu ion o an indus ial wheel loade
o p o ide on- he-go weighing o ucks. Desc ibed measu -
ing sys em consis s o he sensing elemen s (s ain gauges),
which we e based on h ee locally made load pins ansduce s
eplaced he exis ing pins be ween he wheel loade a m
and he bucke . Sys em accu acy is wi hin accep able ange
limi 0.7 % and 1 % o he measu ed magni udes unde
s a ic and dynamic measu emen s, espec i ely. Radoiˆ
cić [20]
p esen ed a measu ing sys em ha is based on a p essu e
senso moun ed di ec ly wi hin a hyd aulic pis on, which is
used o li he was e con aine s. Radoicic and o he s [21]
desc ibe an al e na i e sys em o con inuous ehicle weigh-
ing du ing was e collec ion while in mo ion, which is based
on s ain gauges. Thei de ia ions in he measu ed weigh
alues ha e no exceeded 0.5 %. The collec i e behind a i-
cle [22] desc ibes a sys em whe e he ca go weigh du ing
loading is de e mined by he gas p essu e in he suspension
cylinde s a he ime o he oscilla ion ending and a he
s a o he ib a ion smoo hing p ocess. The weighing e o
is de ined by a maximum o 3 %. A icle [23] desc ibes a
ehicle on-boa d weighing sys em based on BP (Back P opa-
ga ion) neu al ne wo k. The eam ca ied ou an expe imen al
measu emen s o uck axles de o ma ion, caused by a ious
ehicle loads. The esul s show ha he load measu emen
e o is wi hin 5 %. Based on he p e iously men ioned
s udies, i can be clea ly decla ed ha a simila app oach ( he
use o ibe -op ic senso s) in OBW sys ems has no ye been
published.
Va ious dynamic was e weighing sys ems a e cu en ly
gaining on impo ance and a e o en pa o a newly manu ac-
u ed ga bage ucks. Since he ga bage is o en also ga he ed
by olde ehicles, a simila sys em mus be e oac i ely
ins alled in o hese olde ehicles as well. Uni e sal mea-
su ing sys ems can be e y expensi e, wi h p ices eaching
up o uni s o ens o housands o dolla s, o example
On-boa d ehicle weighing (Hawkley G oup Limi ed, Bo -
don Hampshi e, UK), AE Weighing Sys ems (AE Van de
Vlie , Tu nhou Belgium). Complex in eg a ion and design
changes a e also equi ed ( o u he in o e e o men ioned
publica ions). These adjus men s a e spanning om suspen-
sion sys em adjus men s o comple e edesigns. These issues
we e used as a mo i a ion o he au ho ’s eam o implemen a
new simple and e o i iendly sys em o weighing munic-
ipal was e.
The main pa ame e s o cu en ly used weighing sys ems
a e summa ized in Table 1, co e ing he e o a es, whe he
he sys em can be e o i ed and whe he i is an ex e -
nal (s andalone) o in e nal (ins alled di ec ly in o he ehicle)
sys em.
TABLE 1. The summa y o esea ched municipal was e weighing sys ems.
Ou o iginal weighing solu ion is based on ibe op ic
senso s, speci ically ibe B agg g a ings. The en i e sys em
can be e o i ed in o a ga bage uck and, due o i s small
size and weigh , can be ins alled oge he wi h FBG senso s
di ec ly on he ga bage ucks li ing equipmen , wi hou any
addi ional modi ica ions o he ehicle. Thanks o he use
o powe measu emen s o in o ma ion e alua ion, he ligh
sou ce in he o m o Ligh -Emi ing Diode (LED), and con-
en ional low-cos FBG senso s he p ice o he whole sys em
is app ox. $2000 (coun ing only he necessa y ma e ial). The
applicabili y, usabili y and accu acy o he p esen ed sys em
is de e mined by an ini ial s udy (4 mon hs) on a eal es ing
ga bage uck and s anda d 0-100 kg con aine s.
II. ANALYSIS OF SUITABLE PLACES FOR INSTALLATION
OF FIBER BRAGG GRATINGS
The designed weighing sys em based on ibe B agg g a -
ings echnology was es ed on a selec ed commonly used
ga bage uck (MAN TGS 28.360 6 ×2-4 BL). The li ing
sys em o a ga bage uck is gene ally o med by a s eel
ec angula solid p o iles, which a e connec ed by pins and
d i en by a hyd aulic pis on. The weighing sys em is based
on he mechanical s ess o hese p o iles du ing he emp ying
o ga bage bins. This mechanical s ess causes measu able
de o ma ions o he p o iles.
The in oduc o y pa o he esea ch was mainly ocused
on he selec ion o sui able loca ions o B agg g a ings and
unde s anding o he dynamic beha io o de o ma ion o ces
on indi idual pa s o he li ing sys em du ing he dumping
o ga bage bins.
The esis ance oil s ain gauges we e chosen as a sui able
echnology. Resis ance s ain gauges a e used as a sensing
elemen o a ious de o ma ion o ces and a e a s anda d-
ized solu ion o de o ma ion sensing. The iNET-555-EU
measu ing con ol panel (GW Ins umen s, Cha les own,
USA) and SGD-3/350-LY11 (Omega Enginee ing, No walk,
USA) esis ance oil s ain gauges we e selec ed o he
measu emen s.
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M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
Foil s ain gauges we e ins alled in p eselec ed loca ions,
whe e he la ges loads we e p esumed. These loca ions we e
p ede e mined by an ea lie simula ion o li ing sys em. Six
oil s ain gauges we e i ed di ec ly o he p o iles o he
li ing sys em (Fig. 1) – he posi ions a e ma ked as P1 o
P6. Th ee oil s ain gauges we e moun ed on he uppe a m
o he li ing sys em, while h ee o he we e moun ed on he
lowe a m.
FIGURE 1. Ga bage uck li ing sys em wi h p ede e mined oil s ain
gauges loca ions.
Based on an ini ial s udy, a se o epea ed ‘‘emp ying
cycles’’ was pe o med on wo ypes o plas ic ga bage bins
(ga bage bin A: olume 120 li e s, con aine weigh 10 kg;
ga bage bin B: olume 240 li e s, con aine weigh 15kg).
Da a ga he ed du ing hese ini ial es we e used as a basis
o u he analysis. In he ini ial s udy, he ‘‘emp ying cycle’’
was ca ied ou wi h bo h emp y bins and bins wi h p ede-
e mined weigh s (10-100 kg, 10 kg s ep). The ou pu was
used o p ede e mine he mos sui able loca ion o he B agg
g a ing senso s on he li ing sys em. Based on he analysis
o he ga he ed da a - whe e he magni ude o he esponse
o de o ma ion, he dependence on he weigh o he ga bage
bin con en s and he s abili y du ing he ‘‘emp ying’’ p ocess
we emoni o ed-posi ionP5wasselec edas hemos sui able
spo o moun ing o he ibe B agg g a ing senso .
A ypical wa e o m cap u ed by he oil s ain gauge
loca ed a he selec ed posi ion (P5) can be seen in Fig. 2. The
example ep esen s he speci ic ‘‘emp ying cycle’’ o 240 l
ga bage bin weighing 30 kg. Phase 1 is a ‘‘wa ming up’’
4 second long in e al, whe e he whole li ing mechanism
is es ing. This phase is ollowed by Phase 2, which ep e-
sen s he li ing and emp ying p ocesses and can be u he
di ided in o h ee pa s. Pa 2a ep esen s he beginning o
he li . This sec ion is cha ac e ized by oscilla ion o he
li ing sys em, wi h subsequen slow a enua ion in a ime
in e al o abou 0.7 s. Pa 2b ep esen s he li ing p ocess,
whe e he de o ma ion o he li ing a m a posi ion P5 is
a i s maximum, ollowed by a signi ican impac caused by
connec ion o he wo main mo ing pa s o he li ing a m.
FIGURE 2. A ypical wa e o m cap u ed om he s ain gauge du ing
emp ying cycle.
Pa 2c ep esen s he las impac o he a m on he s uc-
u e o he ehicle, which again causes he li ing sys em o
oscilla e.
The analyzed da a showed ha he de ec ed de o ma ion a
he P5 loca ion is in he measu able ange ±100 µs ain and
a e he e o e also measu able by ibe B agg g a ings.
III. BRAGG GRATING SENSORS, BASIC PRINCIPLE AND
INSTALLATION OF THE DESIGNED SYSTEM
A. FIBER BRAGG GRATING (FBG)
Fibe B agg g a ing (FBG) is o med by a s uc u e wi h pe i-
odic a ia ion in he index o he ibe co e. In his s uc u e,
he e ac i e index o he co e n1al e na es wi h an inc eased
e ac i e index n3=n1+δn, whe e δnis he induced e ac-
i e index which esul s om exposu e o he pho osensi i e
op ical ibe o UV ligh . Figu e 3shows he s uc u e and he
unc ional p inciple o he B agg g a ing.
FIGURE 3. S uc u e and ope a ional p inciple o he B agg g a ing.
The s uc u e o he B agg g a ing e lec s a na ow e-
quency band o he b oadband ligh and ansmi s he o he s.
The cen al pa o he e lec ed spec um is called he B agg
wa eleng h λBand is gi en by ela ion (1):
λB=2ne 3, (1)
whe e ne is he e ec i e e ac i e index o he g a ing in
he ibe co e, 3is he g a ing pe iod. O he wa eleng hs a e
ansmi ed wi hou a enua ion.
The B agg wa eleng h is he geome ic and op ical p op-
e ies ha change unde he in luence o mechanical and/o
he mal s esses. I is impo an o men ion he equa ion (2),
whe e he B agg wa eleng h change, he ela i e de o ma ion
99052 VOLUME 9, 2021
M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
and empe a u e change is exp essed by:
1λB
λB
=kε+(α3+αn)1T,(2)
whe e 1λB ep esen s B agg wa eleng h shi , kis de o -
ma ion coe icien , εis de o ma ion, α3is he coe icien o
he mal expansion, αnis he he mo–op ic coe icien and 1T
is change o empe a u e. [24]
B. MEASURING POWER OF THE DEFORMATION BY A
PAIR OF BRAGG GRATINGS
In mul ipoin senso applica ions, he wa eleng h-di ision
mul iplexing is one o he mos widely used and simples
me hods. This mul iplexing me hod is based on he ac
ha indi idual B agg senso s a e made wi h di e en B agg
wa eleng hs. The op ical signal e lec ed om se ies o FBG
senso sis o med by he sum o pa ially non-o e lapping
e lec ion spec a. Moni o ing he p ecise shi o B agg spec-
a equi es he employmen o cos ly e alua ion uni , which
is o en based on a wide-spec al sou ce, a di ac ion g a ing
and a as CCD linea de ec o . [25]
The e o e, in case o single-pu pose applica ions wi h a
limi ed numbe o FBG senso s, i is o en ad ised o an-
si ion o simple powe measu emen s. This measu emen
uses he con e sion o he B agg wa eleng h shi o change
o he op ical powe . The mos commonly used me hods a e
he deploymen o he wa eleng h-dependen il e [1], [2],
a wa eleng h-dependen couple [4], [5] o a sys em wi h
wo Chi ped B agg g a ings wi h o e lapping spec a [6], [7].
In his a icle, he p e iously men ioned me hod o wo B agg
g a ings wi h o e lapping spec a, was used o weigh he
was e and educe he long- e m cos s.
The scheme o p oposed measu ing sys em (please see
Fig.4) used wide-spec um LED (ligh -emi ing diode), ype
SLD1550S-A1 1 mW (Tho labs, New on, New Je sey, USA),
op ical ci cula o 1550 nm (Guilin GLsun Science and Tech
G oup, Guilin, Guangxi, China), pai o B agg g a ings wi h
pa ially o e lapping e lec ion spec a wi h pa ame e s men-
ioned below. The e lec ed ligh is ed o a pho ode ec o
(InGaAs APD G10899-01K 1.55 µm, Hamama su Pho onics
K.K, Japan), digi ized by an A/D con e e , and p ocessed
by a mic o p ocessing uni ha e alua es he weigh o
he was e.
The senso pa o he p oposed sys em consis s o a mea-
su ing senso (FBGM) and a e e ence senso (FBGR). The
measu ing senso is di ec ly a ached (by glue) o he p e i-
ously men ioned posi ion (P5) o he li ing sys em, so he
de o ma ions om he s uc u e we e ansmi ed o he g a -
ing s uc u e o he measu ing FBGM senso . The e e ence
senso is ins alled wi h espec o de o ma ion insensi i i y
(by app op ia e encapsula ion as de ined below) on he li ing
sys em o he ga bage uck. The ad an age o his app oach
is au oma ic empe a u e impac compensa ion, because bo h
used senso s a e a ec ed by he empe a u e equally.
Figu e 5shows he spec a o bo h FBGM and FBGR
senso s, whe e he ed colo o he spec um co esponds o
FIGURE 4. Scheme o ibe -op ic sys em wi h a pai o B agg g a ings.
FIGURE 5. Basic p inciple o a sys em wi h a pai o g a ing senso s
whose spec a pa ially o e lap: (a) a measu ing senso in he unloaded
s a e; (b) measu ing senso in loaded s a e.
he FBGR e e ence senso and he blue colo co esponds
o he FBGM measu ing senso . Figu e 5(a) desc ibes he
s a e o he spec a when he FBGM measu ing senso is
no in luenced by he measu ed de o ma ion (due o he
weigh o he was e bin du ing he dumping p ocess). In his
case, he e lec ed powe P1consis s o bo h e lec ed spec-
a, his powe en e s he e alua ion uni (In e oga o pa ).
Figu e 5(b) shows he spec a wi h he loaded FBGM senso
(due o he weigh o he ash in he ash bin), which di ec ly
co esponds o he inc eased dis ance be ween bo h spec a
and he consequen inc ease o he a ea unde bo h spec a
cu es. The powe P2(P2>P1) is used o e alua ion.
Fo he pu pose o his speci ic measu emen scena io,
a linea wo king a ea is used, which is loca ed a he begin-
ning o he con e sion cha ac e is ic ( o de ails see Fig. 6).
The de e mina ion o a sui able spec al con igu a ion
o a pai o B agg g a ings was based on ou p e ious
esea ch [26] in he Op iSys em en i onmen . Di e en spec-
al wid hs o he B agg g a ings, hei spec al sepa a ion
and e lec ance we e chosen o achie e he con e sion cha -
ac e is ic app oaching he linea cou se wi h high s eepness
and su icien measu ing ange. The ollowing Fig. 7shows
he cha ac e is ics o he spec um wid hs o 300 pm, wi h a
e lec ance o 95%. This cha ac e is ic ( o a spec um wid h
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M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
FIGURE 6. Con e sion cha ac e is ic o he men ioned measu ing
p inciple wi h a linea dependence o he measu ed powe on he
de o ma ion.
FIGURE 7. Analysis o a sui able spec al spacing o a pai o B agg
g a ings usable o achie e he bes possible linea i y o he con e sion
cha ac e is ic in he ange om -100 o 100 µs ain.
o 300 pm) can be w i en by a linea ela ionship p1ε+p2
wi h he R-squa e pa ame e R2=0.9946, whe e εis de o -
ma ion, p1=0.2973, and p2=104.5. I is a combina ion o
pa ame e s ha exhibi s accep able p ope ies.
Wi h ega d o he linea i y and s eepness o he con-
e sion cha ac e is ic and he equi ed measu ing ange
o 200 µs ain (see Chap e II), a a ian wi h a spec al
spacing o bo h B agg g a ings o 300 pm was chosen. The
selec ed con e sion cha ac e is ic shows (in he ange om
−100 µs ain o +100 µs ain) a s eepness o 0.3 µW/µs ain
wi h R-Squa ed pa ame e o 0.994. The ac ual pa ame e s o
he B agg g a ings a ec ed by he p oduc ion me hod can be
seen in Table 2.
TABLE 2. Pa ame e s o used B agg g a ings.
C. INSTALLATION OF FBG SENSORS
B agg g a ings in polyimide p o ec ion (SM ibe , G.652.D.
s anda d) on one ibe wi h a spacing o 25 cm we e used o
FIGURE 8. Diag am o he ga bage uck li ing a m wi h loca ions o FBG
senso s ( he ed line ep esen s he op ical ibe , in which he dashed
lines a bo h pin A and B ep esen B agg g a ing).
he ins alla ion. Polyimide ecoa ing o B agg g a ings was
chosen due o he s onge igh ness o he p ima y p o ec ion
and he op ical ibe and hus ensu ing he be e ansmission
o de o ma ion e ec s o he op ical ibe wi h he FBG
s uc u e. The loca ion o he measu ing senso (FBGM) and
he e e ence senso (FBGR) on he li ing sys em is shown
in Fig. 8and Fig. 9. The FBGM senso is ins alled by a ixed
join (Loc i e EA 3430, Düsseldo , Ge many) a posi ion
P5 as men ioned in p e ious simula ions.
A simpli ied diag am o he li ing de ice can be seen
in Fig. 8. The li ing sys em is a ached o he uck by a
connec ing pin A. Ano he pin – Pin B – is i ed a he
bending poin o he a m. A hyd aulic pis on used o li he
whole a m is a ached di ec ly o he pin B. When he a m is
li ed by he pis on, he ga bage bin (o con aine ) is aised
o maximal heigh and he con aine is emp ied. A FBGR
e e ence B agg g a ing is loca ed nea pin A. This speci ic
loca ion was picked, since he e a e only e y small de o ma-
ions, co esponding o wo o de s o magni ude lowe alues
han in he place behind he pin B, whe e he measu ing B agg
g a ing FBGM is loca ed.
The e e ence FBGR senso was loca ed in he place wi h
he smalles de o ma ion, as was de e mined by he p e ious
measu emen s, which employed oil s ain gauges. The e -
e ence g a ing was also no a ached di ec ly o he su ace
o he s uc u e. I was sepa a ed by a se e al millime e
laye o oamed polyme ic ma e ial. Due o his loca ion and
speci ic a achmen , he ansmission o de o ma ions and
ib a ions om he s uc u e o he e e ence g a ing was
p e en ed. Due o he ela i ely small dis ance o bo h senso s
and he employmen o he p e iously men ioned he mally
conduc i e sealan , a compa able he mal s ess o bo h FBG
g a ings is achie ed.
Du ing he s a ic expe imen al measu emen s, he e we e
only e y small empe a u e di e ences in bo h deployed
loca ions. Acco ding o he measu emen s, he oscilla ion
o empe a u e led o a change in he spec al sepa a ion
(be ween FBGRand FBGM) by a maximum o 20 pm. Due o
he su icien ly la ge wo king a ea o he ans e cha ac e is-
ic (see Fig. 7), hese changes do no a ec he p inciple and
99054 VOLUME 9, 2021

M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
FIGURE 9. Ins alla ion o a pai o FBG on he li ing sys em o he
ga bage uck.
FIGURE 10. The p ocess o emp ying an emp y bin - ma king (blue colou )
he change in powe 1Ppeak o ampli ude me hod.
accu acy o he weighing p inciple. In addi ion, he accu acy
o weighing is no a ec ed, as he measu emen s o as
dynamic phenomena a e no a ec ed by he slowly changing
empe a u e.
IV. EVALUATION PRINCIPLES
Based on he ob ained da a, wo possible me hods o sig-
nal p ocessing we e de ined o ind he op imal con e sion
cha ac e is ic o he ga bage bin weigh . The i s one is an
ampli ude me hod ha moni o s he inc ease in ampli ude
du ing emp ying (Fig. 10), while he second one examines
he oscilla ion pe iod o he li ing sys em (Fig. 12).
A. AMPLITUDE METHOD
Ampli ude me hod is based on he inc ease in signal ampli-
ude du ing he emp ying p ocess. The moni o ed alue is he
di e ence in powe ampli ude 1Ppeak be ween he a e aged
alue shi ed o ze o in phase 1 and he maximum alue o
Ppeak in phase 2 (o pa 2b) – o u he in o e e o Fig. 2
and Fig. 10.
This me hod was used o pe o m a se ies o es measu e-
men s du ing he ‘‘emp ying p ocess’’ wi h di e en weigh s
spanning om 0 o 100 kg in s eps o 10 kg. Figu e 11 shows
he a iance o powe change 1Ppeak and he de ia ions om
FIGURE 11. Ampli ude me hod o was e weigh es ima ion: (a) box plo
o changes in emp ying p ocess; (b) he de ia ion o he powe change
om he a e aged alue o di e en weigh s.
he a e aged alue o he powe change using a box plo s o
all measu emen s (a o al o 220 cycles o emp ying cycles,
20 o each weigh ).
The dependence o he a e age alue o he change in
powe on weigh is linea wi h he eliabili y o R2=0.9935.
Based on he alue o eliabili y, i is clea ha he a e age
alues o pe o mance changes a e linea ly dependen o he
weigh o he was e bin con en s. The me hod o con en mass
calcula ion can be exp essed by he ollowing equa ion (3):
w=0.311Ppeak −33.03.(3)
Based on he equa ion (3) and he calcula ed cha ac e is-
ics, he ela i e e o o he ga bage bin weigh was es ima ed
as 14 %. The men ioned solu ion and he me hod o weigh
calcula ion is only app oaching he eal alues – he e o e i
is no su icien o was e collec ion op imaliza ion. Fo his
eason, a second me hod based on he ib a ion esponse o
he li ing sys em was p oposed.
B. TIME METHOD
A he beginning o he ‘‘li ’’, he cou se o de o ma ion is
cha ac e ized by he oscilla ion o he li ing sys em, which is
dampened quickly, see Fig. 2(phase 2a). In e ms o mechan-
ical ib a ion, he equency o hese ib a ions depends on
he magni ude o he igidi y o he li ing sys em and he
weigh o he ga bage bin. The basic p inciple o he signal
p ocessing can be seen in Fig. 12. The beginning o he
wa e o m is cu , so ha a sec ion o 40 ms be o e he i s
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M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
oscilla ion is s ill p esen . Subsequen ly, an o se shi is
applied on he y-axis o he alue o 0. Then he ea pa o he
signal is cu o , so ha only an in e al o 0.7 s is le . In he
nex phase, local maxima (posi i e peaks) a e iden i ied, ime
in e als be ween adjacen maxima a e calcula ed and hese
in e als a e a e aged. The same p ocess is ca ied ou wi h
local minima (nega i e peaks).
FIGURE 12. Basic p inciple o ime me hod wi h local posi i e/nega i e
peaks, which a e used o de e mina ion o he oscilla ion ime pe iod o
li ing sys em.
This me hod was also used in simila scena io as in he
p e iously men ioned ampli ude me hod (emp ying ga bage
bins weighing om 0 o 100 kg wi h s ep o 10 kg).
Ga he ed da ase was used o de e mine he dependence
o he oscilla ion ime pe iod on he weigh o he was e.
Figu e 13 shows he a iances o he oscilla ion pe iod and
he de ia ion om he a e aged alue. The oscilla ion pe iod
is calcula ed as he a i hme ic mean be ween he pe iods
ob ained om posi i e local maxima and he nega i e local
maxima.
The dependence o he a e age alue o he change in
powe on weigh is linea wi h he eliabili y o R2=0.996.
Based on he alue o eliabili y, i is clea ha he a e age
alues o pe o mance changes a e linea ly dependen o he
weigh o he was e bin con en s. The me hod o con en mass
calcula ion can be exp essed by he ollowing equa ion (4):
w=0.921T−116.15.(4)
Based on he equa ion (4) and he calcula ed cha ac e is-
ics, he ela i e e o o he ga bage bin weigh was es ima ed
as ±6 %. The p esen ed solu ion o municipal was e weighing
is compa able o comme cially a ailable solu ions and shows
a p omising solu ion o was e collec ion op imaliza ion,
while also o e ing signi ican ad an ages such as simple
ins alla ion and much lowe p ice.
V. LONG-TERM TESTING
The e i ica ion o he unc ionali y and i s accu acy was
ca ied ou du ing a 4-mon h pilo s udy, in which he sys-
em was subjec ed o a o al o 2589 emp ying cycles wi h
a p e iously known weigh o was e in ga bage bins. This
long- e m measu emen was no ca ied ou in eal condi ions,
since i was necessa y o know he exac weigh o he was e o
de e mine he quali y pa ame e s ela ed o he accu acy and
FIGURE 13. Time me hod o was e weigh es ima ion: (a) box plo
ep esen ing changes in ime pe iods du ing emp ying p ocess; (b) he
de ia ion o he pe iod change om he a e aged alue o di e en
weigh s.
ep oducibili y o he weighing. The long- e m measu emen
was ca ied ou in he backg ound o he company ha p o-
ides was e collec ion.
The expe imen al se up was he same as in he analysis o
he weighing p inciple in he p e ious Chap e . A ga bage
uck (MAN TGS 29.360 6 ×2-4 BL) wi h a pai o B agg
g a ings ins alled on he li ing de ice was used o he mea-
su emen (see Fig. 9). The signal om he B agg g a ings was
ou ed ia an op ical cable o he e alua ion uni loca ed in
he ea o he ehicle. The op ical signal is hen con e ed o
an elec ical digi al signal using a con en ional pho ode ec o
and an A/D con e e wi h sampling equency o 500 Sps.
This disc e e signal is p ocessed in he µPC uni and he
es ima ed weigh o was e in he con aine is s o ed in he
in e nal memo y (Fig. 4). A 120 l was e collec ion con aine
wi h a ious es weigh s om 10 o 100 kg was used o es
he sys em.
The esul s o he 4-mon h pilo s udy can be seen
in Fig. 14. Fig 14(a) shows all measu emen s, whe e each
poin ep esen s one ga bage dump p ocess. The dependence
o he es ima ed weigh and he ac ual weigh co esponds
o a linea dependence wi h he R pa ame e o 0.9937.
Fig. 14(b) shows he a iance o he weighed weigh s, whe e
he x-axis shows he a e age alue o he es ima ed and ac ual
weigh s, while he y-axis shows he di e ence be ween he
es ima ed weigh and he ac ual weigh . The igu e shows he
con idence band ±1.96 SD (S anda d De ia ion) wi h a wid h
o 8.09 kg and i s mean sys ema ic e o o −0.24kg.
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M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
FIGURE 14. Resul s o was e weighing om a 4-mon h long- e m
measu emen . (a) dependence o he measu ed weigh s o he was e on
he ac ual dump weigh ; (b) absolu e weighing e o ; (c) ela i e weighing
e o ; (d) ep oducibili y o he weighing sys em scena io, de e mined by
he a iabili y o he da a se ou lied by a s anda d de ia ion.
The esul s show ha 97.91% o he measu emen s lie
in he con idence band o andom e o s. Only in case
o 54 dumps ou o a o al o 2589 is he e o g ea e han
he band de ined by wice he s anda d de ia ion. Fig. 14(c)
shows he ela i e weighing e o ela i e o he ac ual weigh
o he dumped was e. Weighing accu acy o weigh s up o
20 kg shows a ela i e a e age e o o app ox. 16%, while he
weigh s o up o 50 kg eached app ox. 7%, and weigh s o e
80% eached app ox. 5%. Due o he lon- e m measu emen ,
which was sp ead o e a pe iod o 4 mon hs (Sep embe o
Decembe ), i is no possible o speci y he epea abili y o
he measu emen , bu he ep oducibili y o he measu emen ,
which indica es he a iabili y o he weighing, can s ill be
epea ed. Fig. 14(d) shows he weighing a iabili y by he
s anda d de ia ion. The s anda d de ia ion was calcula ed o
all weighed weigh s ounded o he nea es kilog am. The
epe i ions o each weigh o was e we e di e en and anged
om 13 o weigh o 100 kg o 47 epe i ions o a weigh
o 59 kg. The smalles s anda d de ia ion o 1.268 occu s
a a weigh o 21 kg, while he la ges s anda d de ia ion
o 2.993 us a a weigh o 98 kg.
The p esen ed weighing sys em shows a weighing accu-
acy o ±4.04 kg wi h a mean alue o -0.24 kg in 97.91% o
was e dumping p ocesses. Based on a 4-mon h expe imen ,
a o al o 140 682 kg o was e was dumped in epea ed es
cycles. In e ms o absolu e alues, a o al o 140 062 kg
was measu ed by he ins alled ibe op ic weighing sys em.
The di e ence was he e o e only 620 kg, which ep esen s
a di e ence o 0.44% compa ed o he eal es ing weigh o
he was e.
The e alua ion sys em was du ing long- e m measu e-
men s loca ed in he ea o he ehicle, whe e he s o age
space o he ehicle ope a o is de ined. This minimized
he necessa y dis ance o he in e connec ing op ical ibe
si ua ed be ween he senso pa and he e alua ion pa ( his
dis ance was app ox. 2m). The encapsula ion o he used
op ical cable (G.657.D) in o a polyme ube wi h Ke la
wi h an ou e diame e o 3mm gua an ees ha he sys em
is esis an o ex e nal in luences (wea he ) and mechanical
damage. The 2m op ical ibe ensu es ha he a enua ion o
he ibe is a negligible alue.
VI. DISCUSSION
This publica ion desc ibes an in oduc o y s udy e i ying
p ima ily he p inciple o unc ionali y and a possible new
di ec ion in he de elopmen o a ibe op ic sys em o
weighing municipal was e when emp ying ga bage bins. The
men ioned solu ion can be addi ionally implemen ed on he
li ing sys em o any comme cial ga bage uck wi hou any
addi ional s uc u al modi ica ions o he ehicle, which is a
signi ican ad an age. Howe e , i should be no ed ha due o
he complex issues o his p oposed solu ion, he esea ch and
long- e m es ing was ca ied ou on a selec ed (commonly
used) ype o ga bage uck. In case o o he ypes o li ing
equipmen , i migh be necessa y o speci y mo e sui able
places o he ins alla ion o FBG senso s and o calib a e
he sys em again. The au ho ’s eam is now ocusing on his
speci ic a ea.
Long- e m es ing was pe o med wi hin he es polygon
and he esul s we e p esen ed o local companies dealing
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M. Fajkus e al.: Fibe -Op ic B agg Sys em o Dynamic Weighing o Municipal Was e: Pilo S udy
wi h he collec ion o municipal was e. Discussions on he
deploymen o his solu ion on a pilo es ca in eal ope a ion
a e cu en ly unde way. The sys em will be supplemen ed
wi h a GPS module and an iden i ica ion code eade in o de
o c ea e a comp ehensi e solu ion o moni o ing he amoun
o municipal was e in o de o educe cos s and s eamline
was e collec ion.
The p ice o he whole sys em, including measu ing sen-
so s, is app ox. $ 2000, coun ing only he necessa y ma e ial.
The au ho ’s eam is awa e o he ac ha a sys em o
dynamic weighing o was e is nowadays a pa o newly man-
u ac u ed ga bage ucks. Ne e heless, i should be no ed
ha he majo i y o companies s ill employ ca s wi h an
olde p oduc ion da e, which in he case o deploymen o
dynamic weighing sys em equi e addi ional ins alla ion o
cus omized equipmen . Uni e sal measu ing sys ems can be
expensi e, wi h p ices eaching up o ens o housands o
dolla s, o example On-boa d ehicle weighing (Hawkley
G oup Limi ed, Bo don Hampshi e, UK), AE WEIGHING
SYSTEMS (Tu nhou Belgium).
Two weigh e alua ion app oaches a e discussed - he
ampli ude me hod analyzing he maximum change in signal
ampli ude and he me hod analyzing he ime pe iods o
damped oscilla ions in he signal. In bo h cases, he HW con-
igu a ion was he same, only he e alua ion algo i hm behind
he A/D con e e was changed. The esul s om he ampli-
ude app oach o signal p ocessing show ha he amoun o
de o ma ion o he a m o he li ing de ice inc eases wi h
inc easing weigh o he was e. Howe e , om he poin o
iew o weighing accu acy, he au ho ’s eam ecommends
using he ime app oach o da a p ocessing, in which a highe
accu acy was achie ed and main ained.
VII. CONCLUSION
This publica ion summa izes he esul s o an ini ial pilo
s udy desc ibing he design, implemen a ion and e i ica ion
o a new ibe op ic sys em based on ibe B agg g a ing
o weighing municipal was e. The p esen ed sys em can be
addi ionally implemen ed on he li ing sys em o commonly
used ga bage ucks. The p inciple o weighing is based on he
measu emen o de o ma ion e ec s and ib a ion esponse
o he li ing equipmen o ga bage ucks du ing he dumping
o ga bage bins.
Two weigh e alua ion app oaches a e discussed - he
ampli ude me hod analyzing he maximum change in signal
ampli ude and he me hod analyzing he ime pe iods o
damped oscilla ions in he signal.
The p esen ed weighing sys em was pilo es ed o
4 mon hs wi hin he es polygon on a eal ga bage uck. The
esul s o he pilo s udy show a ela i e accu acy o ±6 %
in he ange o 0–100 kg o s anda d con aine s in ended o
he collec ion o municipal was e.
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