Extrapolation of weight from smart scale data
Abstract
In the area of human digital twins, the designed model should be as close as possible to the reality. The weight variable is one of the interested parameters of these mathematical models, as well as its interaction with other vital signals. The aim of this paper is including the information gathered from weight sensors of a person in its digital twin. To do this it is described an algorithm that filters and forecasts the human weight to use it in indexes such as BMI. It has been applied to a real sample and the results obtained are good
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P ocedia Compu e Science 192 (2021) 2761–2768
1877-0509 © 2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h ps://c ea i ecommons.o g/licenses/by-nc-nd/4.0)
Pee - e iew unde esponsibili y o he scien i ic commi ee o KES In e na ional.
10.1016/j.p ocs.2021.09.046
10.1016/j.p ocs.2021.09.046 1877-0509
© 2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h ps://c ea i ecommons.o g/licenses/by-nc-nd/4.0)
Pee - e iew unde esponsibili y o he scien i ic commi ee o KES In e na ional.
A ailable online a www.sciencedi ec .com
P ocedia Compu e Science 00 (2021) 000–000
www.else ie .com/loca e/p ocedia
25 h In e na ional Con e ence on Knowledge-Based and In elligen In o ma ion & Enginee ing
Sys ems
Ex apola ion o weigh om sma scale da a
Pablo Caballe oa,*, Juan A. O egaa, Luis Gonzlez-Ab ilb
aUni e sidad de Se illa, ETS Ingenie a In o m ica, A da. Reina Me cedes s/n, E-41012 Se illa, Spain
bUni e sidad de Se illa, Facul ad de Ciencias Econmicas, A da. Ramn y Cajal, 1, E-41018 Se illa, Spain
Abs ac
In he a ea o human digi al wins, he designed model should be as close as possible o he eali y. The weigh a iable is one o
he in e es ed pa ame e s o hese ma hema ical models, as well as i s in e ac ion wi h o he i al signals. The aim o his pape is
including he in o ma ion ga he ed om weigh senso s o a pe son in i s digi al win. To do his i is desc ibed an algo i hm ha
il e s and o ecas s he human weigh o use i in indexes such as BMI. I has been applied o a eal sample and he esul s ob ained
a e good.
c
2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
Pee - e iew unde esponsibili y o he scien i ic commi ee o he KES In e na ional.
Keywo ds: WEIGHT; EXTRAPOLATION; ALGORITHM; DIGITAL-TWIN; SIGNAL PROCESSING
1. In oduc ion
The c ea ion o a human digi al win equi es di e en i al signals, calcula ed indexes and some me ics. Fo
complex models like hese i is necessa y o di ide in simple models which in u n can be ela ed each o he .
The moni o iza ion [1] o he humans and he ea ly disease p e en ion is he inal aim o he human digi al wins,
ying o align he a ge o s a e machine o he model wi h he pa e ns o he human-machine [2]. The la es In e ne
o Things (IoT) de elopmen s [3] ocused on he i ness p o ides o he ma ke a so o comme cial ubiqui ous de ices
[7], in pa icula sma bands and sma wa ches. Some examples such as he eal ime hea a e, he walking o es ing
hea a e, and he sleeping hou s a e s o ed in he sma wa ches like Apple Heal hKi and cloud da abases. This aw
in o ma ion can be que ied by mobile applica ions as well as complex backend sys ems.
On he o he hand, he inc emen o o e weigh and obesi y [4, 5] has also opened he ma ke o new sma de ices,
o ins ance sma scales. The weigh o he body a can be measu ed and eco ded whene e he use s wan .
∗Co esponding au ho . Tel.: +34-605-458-552
E-mail add ess: [email p o ec ed]
1877-0509 c
2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
Pee - e iew unde esponsibili y o he scien i ic commi ee o he KES In e na ional.
A ailable online a www.sciencedi ec .com
P ocedia Compu e Science 00 (2021) 000–000
www.else ie .com/loca e/p ocedia
25 h In e na ional Con e ence on Knowledge-Based and In elligen In o ma ion & Enginee ing
Sys ems
Ex apola ion o weigh om sma scale da a
Pablo Caballe oa,*, Juan A. O egaa, Luis Gonzlez-Ab ilb
aUni e sidad de Se illa, ETS Ingenie a In o m ica, A da. Reina Me cedes s/n, E-41012 Se illa, Spain
bUni e sidad de Se illa, Facul ad de Ciencias Econmicas, A da. Ramn y Cajal, 1, E-41018 Se illa, Spain
Abs ac
In he a ea o human digi al wins, he designed model should be as close as possible o he eali y. The weigh a iable is one o
he in e es ed pa ame e s o hese ma hema ical models, as well as i s in e ac ion wi h o he i al signals. The aim o his pape is
including he in o ma ion ga he ed om weigh senso s o a pe son in i s digi al win. To do his i is desc ibed an algo i hm ha
il e s and o ecas s he human weigh o use i in indexes such as BMI. I has been applied o a eal sample and he esul s ob ained
a e good.
c
2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
Pee - e iew unde esponsibili y o he scien i ic commi ee o he KES In e na ional.
Keywo ds: WEIGHT; EXTRAPOLATION; ALGORITHM; DIGITAL-TWIN; SIGNAL PROCESSING
1. In oduc ion
The c ea ion o a human digi al win equi es di e en i al signals, calcula ed indexes and some me ics. Fo
complex models like hese i is necessa y o di ide in simple models which in u n can be ela ed each o he .
The moni o iza ion [1] o he humans and he ea ly disease p e en ion is he inal aim o he human digi al wins,
ying o align he a ge o s a e machine o he model wi h he pa e ns o he human-machine [2]. The la es In e ne
o Things (IoT) de elopmen s [3] ocused on he i ness p o ides o he ma ke a so o comme cial ubiqui ous de ices
[7], in pa icula sma bands and sma wa ches. Some examples such as he eal ime hea a e, he walking o es ing
hea a e, and he sleeping hou s a e s o ed in he sma wa ches like Apple Heal hKi and cloud da abases. This aw
in o ma ion can be que ied by mobile applica ions as well as complex backend sys ems.
On he o he hand, he inc emen o o e weigh and obesi y [4, 5] has also opened he ma ke o new sma de ices,
o ins ance sma scales. The weigh o he body a can be measu ed and eco ded whene e he use s wan .
∗Co esponding au ho . Tel.: +34-605-458-552
E-mail add ess: [email p o ec ed]
1877-0509 c
2021 The Au ho s. Published by Else ie B.V.
This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
Pee - e iew unde esponsibili y o he scien i ic commi ee o he KES In e na ional.
2762 Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768
In a model, he body mass index [6] is widely used o measu e he s a us in i ness models. Some ac ions can be
sugges ed when he use is unde weigh , o e weigh o mo e.
Due o he in o ma ion is ga he ed om se e al de ices and e e y de ice can ha e one o mo e senso s; he e o e,
he collec ion o samples ha e di e en ime equencies. To ela e he signals and he e o e he collec ions o samples
need o exis in a speci ic momen , so he model is spli in s eps.
The body mass [13] o commonly called weigh has a iny ecu ency compa ed o hea a e so i is needed a
o ecas mechanism o ma ch he alues in one ime s ep. This pape will be ocused on he ex apola ion o he
weigh ecei ed om a sma scale. A e his s anda diza ion p ocess he esul ed samples can be used as da ase o
machine lea ning models o cloud compu ing calcula ions.
The pape is o ganized as ollows. Sec ion 2 exposes he p ope ies o he weigh o ge a pic u e o he p oblem.
Secondly, in Sec ion 3 he ime in e als is de ined. Then, in Sec ion 4 he ex apola ion algo i hm is desc ibed. The
acknowledgemen s a e in Sec ion 6. Finally he conclusions and u he wo ks a e de ailed in Sec ion 5.
2. P ope ies o weigh
Based on he anonymous su ey “habi s o weigh you sel ” made o his pape on in e ne o e 58 people on
Ma ch 4, 2021; he ollowing p ope ies can be in e ed om i s esul s and hey jus i y disc e izing he signal o he
weigh and aking he alues based on he close samples.
2.1. Recu ence
The high a iabili y o he hou o weigh you sel shown in Figu e 1 does no allow o p edic he momen when
he sample o he weigh is ga he ed.
Table 1. Common weigh you sel hou .
Hou Coun Pe cen age
None 8 13.8%
758.6%
8 19 32.8%
9 9 15.5%
10 2 3.4%
11 4 6.9%
12 1 1.7%
19 2 3.4%
20 5 8.6%
21 3 5.5%
None
13.8%
7
8.6%
8
32.8%
9
15.5%
10
3.4%
11
6.9%
12
1.7%
19
3.4%
20
8.6% 21
5.5%
Fig. 1. Common weigh you sel hou om Table 1.
The ecu ency pe week is also highly a iable, shown in Figu e 2. Consequen ly, i is no possible o p edic how
o en he samples a e ga he ed.
Table 2. Numbe o weighing you sel pe week.
F equency Coun Pe cen age
(Weekly) 1 14 17.7%
267.6%
3 12 15.2%
445.1%
5 15 19.0%
(Daily) 7 28 35.4%
Weekly
17.7%
2
7.6%
3
15.2%
4
5.1%
5
19%
Daily
35.4%
Fig. 2. Numbe o weighing you sel pe week om Table 2.
Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768 2763
2.2. Va iabili y
The a iabili y h oughou a day he weigh could inc ease o dec ease signi ican ly based on he quan i y o liquid
o ood, basal me abolic a e [8], ac i i y [9], ho mone le els [10], he equency o bowel mo emen [11]... So, i is
no possible o ecas ing mo e accu a e o an speci ic day.
In he opposi e case, i migh be possible measu e o he weigh ew imes in a sho pe iod o ime and i should
ep esen he same momen . In some cases, mobile applica ions [16] linked o he sma scale ask o a con i ma ion
when he di e ence is oo big. Fo he cu en p oposal, he alue o he weigh in a s ep will be he a e age o he
alues inside he same ime s ep.
3. Time in e al
As i was exposed be o e, du ing he c ea ion o a model he samples o he i al signals a e in di e en equencies,
so i is necessa y o s anda dize in ime in e als. The complex s uc u e [14] has o be con e ed in o a ime in e al
de ined by [s a ,end].
The pa ame e s epSize is he numbe o minu es o one s ep. Fo his algo i hm will be 1 min. So a ime in e al
can be de ined as he pe iod o ime [ i, i+1] whe e iis he beginning o he s ep and i+1.
i+1= i+s epS ize (1)
In he o ecas ing algo i hm some ime in e al me hods will be used, hey a e in e sec and expandMinu es.
3.1. Me hod in e sec
An in e al xin e sec s wi h an in e al ywhen hey sha e pa o hei ime. I is shown in Figu e 3.
in e sec (x,y)=y.end ≥x.s a ∧y.s a ≤x.end (2)
---------------->
x -----S-----E-----
y1 ---------s---e--- y1 in e sec s wi h he igh bounda y o x
y2 --s-----e-------- y2 in e sec s wi h he le bounda y o x
y3 -------s-e------- x con ains y3
y4 --s----------e--- y4 con ains x
Fig. 3. Possible cases o in e sec is ue.
3.2. Me hod expandMinu es
Da e ypes a e speci ic o he p og amming languages, so i is ecommended he usage o a common ep esen a ion.
Hence o h he da es will be ep esen ed in icks1[15] o ma . Due o some sys ems like Apple de ices include he
second p ecision and i is no needed, he smalles p ecision is minu e and he seconds componen can be uled ou .
The cons an icksPe Minu e is he numbe o icks in one minu e, ha is 600 000 000, and i is necessa y o
con e ime di e ence in minu es.
An in e al iis expanded in mminu es when he ield s a in mo ed mminu es be o e i and he ield end is mo ed
mminu es a e i . This me hod is used when he e a e no any samples o a ime in e al and i is need o expand he
sea ch adius.
expand(in e al,m)=[i.s a −( icksPe Minu e ×m),i.end +( icksPe Minu e ×m)] (3)
1One ick is 100 ns (nanoseconds) and da e is he numbe o icks since 12:00, Janua y 1, yea 1 in G ego ian calenda .
2764 Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768
4. P ocedu e
Below, he in ol ed me hods and he esampling p ocess a e desc ibed. The ex apola ion i sel is pa o he
me hod sea chSamples(samples, in e al) and he gene al me hod o s anda dize all he samples is he me hod
ge AllS anda dSamples(samples1,samples2, ... samplesn).
4.1. Fil e ing o bounding alues
When in o ma ion is ex ac ed om a sma de ice, a po en ial p oblem could happen, use s can add manually
alues and consequen ly ha ac ion could be a sou ce o possible e o s.
Based on a da ase [12] o 40 400 samples o heigh o 18 yea s old people, he bounding alues depending on he
gende ha e been ob ained using BMI he o mula can ollow:
bmi =weigh [kg] ÷heigh [m]2(4)
weigh i=bmi ×heigh 2
i(5)
weigh =a e age(weigh i) (6)
Table 3. Ex eme alues o weigh s depending on he gende .
Gende Th eshold
Weigh (kg)
Ex eme
Unde weigh
BMI 16
Weigh (kg)
Mode a e
Unde weigh
BMI 16
Weigh (kg)
Obesi y III
BMI 40
Weigh (kg)
Obesi y IV
BMI 50
Female Minimum 39.50 41.97 - -
Female Maximum - - 98.74 123.43
Male Minimum 45.38 48.22 - -
Male Maximum - - 113.46 141.83
The BMI alues o ex eme unde weigh and obesi y IV ha e been aken as limi s maximum and minimum e-
spec i ely due o he e a e no mo e ex eme ca ego ies. The ca ego ies mode a e unde weigh and obesi y III could be
aken in a mo e es ic i e model because mo e alues a e ou o ange. All he samples whose weigh is ou o ange
should be disca ded. This il e can be applied in ea ly s eps in ou p ocess, so i is no needed o spend space and
p ocessing ime.
4.2. Iden i y ime o ecas bounda ies
All he samples ex ac ed om he de ices usually a e wi hin a ime in e al, so hey ha e a leas a uple o h ee
alues: s a da e (samplei.s a ), end da e (samplei.end) and he signal alue (samplei. alue).
In addi ion o he samples o weigh he e a e also o he samples like hea a e o heigh , and ha bounda ies
belong o he model i sel , so he en i e se o samples is needed. One modi ica ion could be including he cu en ime
in his limi calcula ion so i will y o ex apola e un il hen.
The bounda ies will be a uple o he minimum da e o all he samples o all he signals o he cu en model and
he maximum da e o all he samples.
ge Fo ecas Bounda ies(samples1, ..., samplesn)=[min(x.s a |x∈samplesi),max(x.end|x∈samplesi)] (7)
Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768 2765
4.3. De ini ion o all in e als
I is needed o c ea e a collec ion o ime in e als, one pe s ep. The me hod ge AllIn e alsPe S ep is de ined
in Algo i hm 1.
The esul is a collec ion o s eps. E e y s ep is ollowed by he immedia e nex s ep, and all he s eps ha e he
same size.
Algo i hm 1: ge AllIn e alsPe S ep(samples1, samples2, ... samplesn)
samplesi:Inpu . Se o samples.
Resul : The se o all in e als.
1(globalS a ,globalEnd)←
ge Fo ecas Bounda ies({x.s a |x∈samples1},{x.s a |x∈samples2}, ..., {x.s a |x∈samplesn})
2in e al.s a ←globalS a
3in e al.end ←globalS a +( icksPe Minu e ×s epS ize)
4in e als ←∅
5while in e al.end <globalEnd do
6in e als ←in e als ∪{in e al}
7in e al.s a ←in e al.end
8in e al.end ←in e al.end +( icksPe Minu e ×s epS ize)
9end
10 e u n in e als
4.4. Look o a possible alue
Once he aw alues a e il e ed, Algo i hm 2 desc ibes he p ocess whe e he weigh is assigned o e e y in e al
as well as he es o he se s o samples.
I is possible o ind mo e han one samples, howe e hose alues should be close o each o he so he a e age
me hod is used.
Algo i hm 2: ge AllS anda dSamples(samples1, samples2, ... samplesn)
samples: Inpu . Se o samples. E e y sample has a s a ime, an end ime and a weigh alue.
Resul : The se o all weigh samples.
1in e als ←ge AllIn e alsPe S ep(samples)
2 esul ←∅
3 o each in e al in in e als do
4samplesInIn e al ←sea chSamples(samples,in e al)
5i |samplesInIn e al|>0 hen
6cu en S ample.s a ←in e al.s a
7cu en S ample.end ←in e al.end
8cu en S ample. alue ←a e age(x. alue|x∈samplesInIn e al)
9 esul ← esul ∪{cu en S ample}
10 end
11 end
12 e u n esul
Below in Algo i hm 3 he me hod sea chSamples is de ined. The esul is a se o samples ha a e close o ha
in e al.
The i s pa o he algo i hm co e s he co ne cases o ha ing a educed numbe o samples. This case could
happen when i is he i s ime ha he s anda diza ion p ocess is execu ed.
The second pa ies o il e all he alues ha in e sec wi h he cu en in e al, so we could say ha hey belong
o his in e al.
2766 Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768
In he hi d pa i ies o inc ease he window ime o ca ch a alue. The inc emen is de ined by he pa ame e
sea chS ep, i is he numbe o minu es o be inc emen ed (by de aul is 60). The limi o he sea ch is de ined by
he pa ame e sea chRa e cons an (by de aul i s alue is 4, so he maximum sea ch will be a qua e o he o al
ime). These pa ame e a e isually explained in Figu e 4.
Fig. 4. Visual explana ion o he pa ame e s.
A d awback o s opping he sea ch using maxSea chS ep (Algo i hm 3, line 20) is when he e a e a small se o
samples close in ime hen he di e ence be ween las Ins ance and i s Ins ance is iny, and i is also educed
by sea chRa e so he window ime maybe is no enough. A possible solu ion less es ic i e could be se a minimum
o maxSea chS ep o he leas es ic i e solu ion is emo ing ha condi ion so i always will ind a leas one sample.
Algo i hm 3: sea chSamples(samples, in e al)
samples: Inpu . Se o samples. E e y sample has a s a ime, an end ime and a weigh alue.
in e al: Inpu . Cu en in e al o e alua e.
Resul : The se o samples o a gi en in e al.
1i |samples|=0 hen
2 e u n ∅
3else i |samples|≤1 hen
4 e u n samples
5end
6
7samplesInCu en WindowTime ←{x|x∈samples ∧in e sec (in e al, x)}
8i |samplesInCu en WindowTime|>0 hen
9 e u n samplesInCu en WindowT ime
10 end
11
12 i s Ins ance ←min({x.s a |x∈samples})
13 las Ins ance ←max({x.end|x∈samples})
14 maxS ea chS ep ←((las Ins ance − i s Ins ance)÷ icksPe Minu e)÷sea chRa e
15 in e alS ize ←s epS ize
16 do
17 in e alS ize ←in e alS ize +(2 ×sea chS ep)
18 expandedIn e al ←expandMinu es(expandedIn e al, sea chS ep)
19 samplesInExpandedIn e al ←{x|x∈
samples ∧in e sec (expandedIn e al, cas SampleToIn e al(x))}
20 while samplesInExpandedIn e al =∅∧in e alS ize ≤maxS ea chS ep
21
22 e u n samplesInExpandedIn e al
Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768 2767
4.5. Algo i hm example
An example o his algo i hm is in Figu e 5. The ini ial da a is 5 in e als, om I0 o I4de ined in Table 4. The
algo i hm pa ame e s a e s epSize as 15 (min), sea chRa e as 4 and sea chS ep as 60 (min).
Table 4. Ex apola ion example da a.
In e al S a S a (Da e) End End (Da e) Weigh (kg)
I06 374 678 400 10801/21/2021 00:00 6 374 678 406 10801/21/2021 00:01 99.0
I16 374 687 040 10801/22/2021 00:00 6 374 687 046 10801/22/2021 00:01 98.0
I26 374 695 680 10801/23/2021 00:00 6 374 695 686 10801/23/2021 00:01 98.0
I36 374 704 320 10801/24/2021 00:00 6 374 704 326 10801/24/2021 00:01 99.0
I46 374 712 960 10801/25/2021 00:00 6 374 712 966 10801/25/2021 00:01 96.0
A e unning he s anda diza ion code i will gene a e 384 in e als o 15 minu es pe in e al.
In 0, 1, 2and 3 he alues a e o iginal alues. Be ween 0and 1 he e a e 2 in e als whose alues a e 98.5 kg,
his si ua ion happens due o sea ching a alue, he window ime in e sec s wi h I0and I1. Be ween 2and 3 he same
hing happens as well.
ime
weigh (kg)
I0(99.0)
I1(98.0) I2(98.0)
I3(96.0) I4(96.0)
0 1 2 3 4
Fig. 5. Ex apola ion example.
5. Conclusion and u he wo k
The di icul y o o ecas he weigh inside a day due o i s ecu ency and a iabili y has been exposed.
Some h eshold alues we e p oposed depending on he gende o il e possible w ong alues. Cases o ex eme
unde weigh o ex eme obesi y would be non-allowed alues.
The p oposed algo i hm is eady o be used and i ex apola es he weigh alue o momen s close o he o iginal
ins an . E e y s ep will ha e a disc e e alue o he weigh so i can be used o c ea e a digi al win model in conjunc ion
wi h o he signals. I he alue is ou he sea ch ange hen ha ime in e al could be disca ded i he weigh is needed.
In a gene al pe spec i e he o ecas ed alues a e alid, ne e heless o an speci ic momen he alue will depend
o how a in ime is om a eal alue.
A u u e modi ica ion could be a second pass day by day and con e ing he disc e e alues in a cu e. In e e y
day, he a ia ions a lunch o dinne could be also conside ed ne e heless a esea ch on nu i ional habi s would be
necessa y.
2768 Pablo Caballe o e al. / P ocedia Compu e Science 192 (2021) 2761–2768
6. Acknowledgemen s
This esea ch has been pa ially suppo ed by he E ol ing owa ds Digi al Twins in Heal hca e (EDITH) Resea ch
P ojec (PGC2018-102145-B-C21, C22 (AEI/FEDER, UE)), unded by he Spanish Minis y o Science, Inno a ion
and Uni e si ies.
Re e ences
[1] Kang, JS. & Chung, K. & Hong, E.J. 2021 Mul imedia knowledgebased b idge heal h moni o ing using digi al win. DOI: h ps://doi.
o g/10.1007/s11042-021-10649-x
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