Journal of Southeast U niversity (Eng lish Edition) V o.l 26,N o .1,pp .73-77M ar .2010 I SSN 1003 7985
Physiological signal acquisition syste m
based on w ireless sensor net works
Q iuW enjiao Zhang Y ongkui
(K ey L abo ra t o ry o f Ch ild D eve l opm ent and L earn i ng Sc ience o fM i n istry o f Education ,Southea st U n i v ersity ,N anji ng 210096,Ch i na)
Abstr act :B ase d on w ireless sensor net w orks ,a physi o l ogical
si gnal acquisiti on syste m is pr oposed .The syste m is use d i n classroo m education in order t o understand t he physi o l ogical c hanges i n t he students .I n t he s y ste m,the biolog i cal electrical si gnal relate d to student atte n ti on a nd e m oti on states ca n be m easur ed by electrocar d i ogr aphy signals .The b i oel ectri cal signal is digitali zed at a 200H z s a m p ling rate and is tra n s m itted by t he Z ig B ee protoc o.l S i m u lta neously ,t he B l uet ooth technology is als o e m be dde d i n the nodes so as to m eet the high sa m pli ng rate a nd the high ba nd w i d t h tra n s m issi on .The syste m can i m p l e m ent them on it o ri ng tas k s for 30students ,and t he experi m ental resu lts of usi ng t he syste m i n t he cl assroo m are propose d .Finall y ,t he a pplicati ons of w irel ess se n s or net w orks used in e ducati on is als o d iscussed .K ey w or ds :w ir eless sensor net w or k ;physi o l ogical si gna;l e du cati on
Recei ved 2009 07 20.Biographies :Q i u W en ji ao (1969 ),m ale ,graduate ;Zh ang Y on gku i (corres ponding au t ho r),m ale ,do ctor ,ass ociat e pro fess or ,yzhangb @s https://www.doczj.com/doc/215525574.html, .cn .
Foundati on ite m:The N ati ona lNatural S ci en ce Foundation of Ch i na(No.60775057).
C itati on :Q iu W en ji ao,Zh ang Y on gku.i Phy si o l og i ca l signa l acqu isition s y st e m based on w i rel ess sen s or net w ork s[J].J ournal o f SoutheastU niver sit y (E ngli sh Ed iti on ),2010,26(1):73 77.
A
lthough the attent i on state and e mot i ona l state of stude n ts dur i ng the lear n i ng process belong to the psyc holog ica l do m a i n,it can be i ndirectly m easured by physi o l og i cal signals ,suc h as e lectr ocard i ography si gnals and pulse signals .Students and teachers m ental states of attention and e mo ti on in the classroo m m ay be chang i ng dur i ng teach i ng progress ,wh ich can physi o l og i cally acti vate the sy m pathetic and parasy mpathetic division o f the
autono m ic nervous syste m (AN S )[1 2]
.T hese m easurable physi o l og i cal signals can be recorded for the analyses of psyc holog ica l ar ousal of social re w ar ds and punish m ents ,such as posit i ve feedbac k by the teacher s praises or higher exa m i nat i on grades ,even the a mount of a scholarship ,al though the arousal of the autono m ic nervous syste m reac t i ons m ay be a co m plex i ndirect relationship to e m o t i on [3 4]
.Interact i ons bet w een states of the autono m ic nerv ous syste m and cognit i ve perfor m ance have a long trad ition of being a top ic of psycho log ical research .C lassic concepts fro m mo tivat i onal psycho logy have suggested an i nverted u shaped association bet w een unspec ific activat i on and m en
tal funct i oning [5 6]
.A ccor d i ng to this ,the best funct i onal condit i ons are expected atm idrange arousa,l and both over ar ousa l and under arousal are acco m panied by declines in perf or m ance .Cardiovasc u lar psychophysiology has also contributed to this li ne of research ,the respective models re l at i ng changes in card i ovascular act i v ity to facilitation,
i nh i b it i on of i nfor m ation processi ng [7]
or ener get icm ob iliza t i on o f the organis m when faced w ith a situat i on requ iri ng
behav i oral ad j ust m ent [8]
.H o w ever ,although this certai n ly const itutes a benefic i a l appr oach ,e m p irical work i n th is
f i e l d re m a i ns re lati vely sparse [9]
.Both the sy m pathetic syste m and the parasy mpathetic syste m contri bute to cardi
ovascular regulat i on [10]
.Sy mpathetic i n fl uences are trans m itted through efferent fibres to the si nus node ,the m yo cardiu m and the vascularm usc u lature ,and their activati on leads to an i ncrease i n heart rate ,cardiac contract ility and vascular tone .Parasy mpathetic i nfl ue nces arew i de l y ,but not co mpletely ,restri cted to the m odulat i on of heart rate through i nhibiting sinus node act i v ity .I n addition ,the cardiac baroreflex is involved .I n th i s negative feedbac k loop ,c han ges i n the act i vity of the arterial baroreceptors due to fl uctua tions i n b l ood pressure are responded w ith co m pensatory changes i n heart rate and contract ility .A co mplex net work of brai n ste m un its subserve cardi ovascular autono m ic contro,l e .g .,the nucleus of the so litar y tract(NT S),the dorsalm otor nucle us(DMN ),the nucleus a mbiguous(NA )and the rostral
ventrolateral medulla(RVL M )[11]
.B ilateral direct and i ndi rect c onnecti ons ex ist bet w een this net work and cortical areas ,which for m an m i portant li nk bet wee n cardi ovascular
regulation and cogn ition [12-13]
.The present study am i s at in vest i gat i ng relationsh i ps a mong features of sy m pathetic ,para sy mpathetic and bar oreflex car d i ovascular control and atten tional perfor mance .
To collect these physi ca l and mental states data i n real tm i e and objectivel y ,a hybrid w ireless sensor net w ork is desi gned as the subjects of a teac her and st ude nts are mob ile .For m edical and ho m e usage ,li ce nse free IS M (i ndustr y ,sci ence ,m edical)radio frequency(RF )o f 2 4G H z Z i gBee w ire
l ess sensor node technology is usef u l [14 18]
.
1 Syste m D escripti o n
A s a secondary ai m ,the study i nvestigates i nter i nd i v i d ual differences i n task i nduced cardiovascular m odula
t i ons .Porges [19]
postulated an associat i on bet w een resti ng cardiac vagal tone and the ex tent o f card i ovascular react i v i ty .Th is is consistent w ith stud i es that have revealed m ore pronounced heart rate responses to var i ous st i m u li i n chil dren and adults w ith higher baseline heart rate variabili ty [19 21].Cardiovascular reacti v ity to cogniti ve de m a nds m ay
also rel ate to task perfor m ance .Duschek [22]
found a positive correlat i on bet wee n systo lic and diastolic b l ood pressure in creases duri ng the executi on o f five attenti on tasks a nd the perfor mance on each o f the m.I n i nfants ,greater decreases of RS A duri ng m ental testing are related to higher f unct i onal
levels [21]
.Inter i ndividual differences in cardiovasc ular mod ulation possi bly reflect different degrees of autono m ic adj ust
m e nt asw ell asmot i vat i on on a task ,both of wh i ch m ay con
tri bute to perfor mance .H o w ever ,i nc onsiste nt findi ngs ,.i e .,m issi ng or even i nverse associat i ons bet w een car d i ovascu l ar reactivity a nd mental perfor m a nce ,have also been repor te d [23 24].T hus ,the curre nt state of research does not a llo w defi nite conclusi ons .The hardware of t he w ireless se nsor net works(W SN s)consists of the data co llecting and trans m itt i ng parts which w ill be attached to students and teachers .To re spect t hese stude nts and teachers w illi ngness to try this ne w device ,the nodes can be c onnected by ECG leads ,but a lso can be rejecte d by the connecti on of leads .The syste m is au to configure d i n the classr oo m.The application of W S N s for physi olog ical si gnal acquisition in the cl assroo m is sho wn i n F ig 1
.
Fig 1 The sm i p l e star conf i gurati on o f w i reless nodes i n class room
1 1 D ata collecti ng and trans m itt i ng parts
T his part is desi gned to collect and trans m it physiolog i ca l
data fro m t he subjects [3]
.W e collect t w o kinds of physi o l og i cal signals :electr ocar d i o si gnals and pulse si gnals fro m the subjects in this research .AD620is chosen as the pre a mpli fier for the a m plification of the weak bi oelectrical signals of 10to 20mV .The ECG uses three standar d lm i b leads (left ar m,ri ght ar m,right leg).T he pulse sensor uses PVDF pie zoelectric fil m w ith a te m perature co mpensati on co mpone nt and an i ntegrated si gnal circuit .
A fter pre a mplification of about 100tm i es ,the signal is subjected to l o w pass and hi gh pass filters (5to 100H z).T o reduce the 50H z po w er li ne i nterfere nce ,the addit i onal notc h f ilter is designed before the signal is pro m oted to a posi tive DC level of 1 5V.The har dware block diagra m and cir cuit are shown i n F ig 2and F ig 3.F ig 4sho w s the picture of the se nsor node .
The a nal og si gnals ar e di gitali zed usi ng a n A t me ga128m icr ocontroller s on c hi p ADC at a 200Hz sa mpli ng rate
because
Fig 2 Phy si o l og i ca l signa l acquisiti on hardw are block d i ag ra
m
F i g 3 C ircuit pri nc i p l e b l o ck diagra m o f sen s o r i nput un
it
F ig 4 P i c t ure o f t he senso r node
the frequency range of the physiolog ical si gnal is fro m 5to
100H z .U si ng a hard w are SPI i nterface ,t he collected data are trans m itted by the w ireless sensor net wor k w it h the Z i g Bee protocol by a CC2420RF chip .A s t he gate way to a per sonal co mputer (PC ),the sink node co mm un icates w it h the PC thr ough a RS 232i nterface .
1 2 Soft w are chart of data co llect i ng and trans m itting parts 1 2 1 Topo l ogy confi gurati on of theWSN T he WSN is expected to realize t he dyna m ic m anage m ent o f nodes ,suc h as the j o i nt and leave of the nodes ,serv ice d iscovery ,and dev ice auto configurat i on .The topology con tr o l can adapti vely organize certa i n numbers o f nodes to a net by certain m echan is m s .W e establish a star net wor k i n the intelli gent classr oo m.The sink node init i alizes the net work ,broadcasts its net work address and sca n c hanne,l and receives responses fr o m the ter m inal nodes ,whil e the ter m i nal nodes atte mpt to seek and joi n the net after i n itial
ization [4]
.
1 2 2 Task sc he duling m echanis m I n our syste m,w e realize tasks such as data acqu isit i on ,storage ,processi ng and tr ans m ission ,usi ng the sm i ple F I F O (first in first out)task scheduli ng .The data str ucture used
74Q i u W en ji ao ,and Zhang Yongku i
i n the F I FO is a c irc ular que ue ;eac h ele m ent i n it i s a func t i on po i nter ,po i nti ng to the head address of the releva nt task .A ny task m ust enter t he task queue by a task subm it t i ng f unction and c ha nge the rear poi nter ,wh ile it can only run the task runn i ng functi onwhen t he front poi nter points to its function pointer .The tasks i n the queue w ill be exec uted successi vel y .A task can appear as one kind of operat i on ,wh ic h can only be interrupted by events such as cloc k i nter ruption ,A /D interrupti ons and so on ,but not by any other
tasks [14]
.
1 2 3 D esi gn of data packet The space nodes i n the classr oo m can collect vari ous phys i o l og ical data of st ude nts and env ir onm e nta l data .I n our sys te m,we use si x A /D channels f or the co llection of the si g nals of the ECG,2 axis accelerat i on ,pressure ,te mperature and hu m i d ity ,respectively .W e asse mble the gathered data (H ere it i s the pay l oad of the data pac ket)and so me other
control i nfor m at i on i nto a data packet [15 16]
.T he fra m e contr o l fi eld w ith a 2 byte leng t h defi nes the control infor m ati on or fra m e for m at .The data seque nce nu mber i de ntifies the data packets in an orderly fashion .The address conta i ns t he PAN I D ,destinat i on node s address and source node s address .T he payload is the data of si gna ls w e co llect fro m the students and the environment of the classroo m.W e put these data into a n array ,storing ECG,x axis accelerati on ,y ax is acceleration ,z ax is acceler at i on and pressure in seque nce for 5tm i es of circular sa mpling ,w ith te mperat ure and hu m idity data at t he e nd of the array . T he soft w are design of our proposed syste m is based on the Z ig Bee protoco.l H o wever ,our collected data has a h i gh da
ta rate c o m pared to the ho me control syste m [25]
.W e take package trans m issi on m ethods to m i prove net wor k perf or m ance .F ig 5and F ig 6sho w the flo w c harts of the ter m i na l node and the sink node ,respective l y
.
Fig 5 F l ow cha rt o f t he ter m i na l
node
Fig 6 F l ow cha rt o f t he si nk node
1 3 G raphical user i nterface desi gn
T he ter m i na l display and the si gna l pr ocess are sho wn i n
F i g 7and F i g 8.A real tm i em onitori ng soft ware m i ple m en ted on the PC is created usi ng the LabV I E W progr a m.On the PC,t he ter m inal display a nd si gnal pr ocess can sho w the data of electrocardi o si gna ls ,pressure signals and accelera tion signals which are all m easured by the body se nsors and tra ns m itte d by the w ireless net wor k syste
m.
Fig 7 A n exa m ple o f m easured
signals
F i g 8 The ter m i na l d is p lay and the si g na l pro ce ss
I nteractions bet w een states of the autono m ic nervous sys
te m and cognit i ve perf or m ance have l ong been a tradit i on as a topic of psyc ho l og ical researc h .C lassic concepts fr o m mo tivational psyc ho l ogy suggested a n i nverted u shaped associa tion bet w een unspecif i c activation and m e nta l function i ng [5 6]
.A ccor ding to this ,the best f unctional conditi ons are expected at m i drange arousa,l and bot h over ar ousal
75
Physiol og i cal s i gnal acqu isiti on syste m based on w i reless se nsor net w orks
and under arousal are acco m panied by decli nes i n perf or m ance.Cardi ovascular psyc hophysi ology has also contri buted to this li ne of researc h,the respecti ve models relating chan ges i n cardi ovascular activity to facilitat i on or inhi biti on of i nfor mat i on processi ng[7]or ener getic m obilizati on of the or ganis m when faced w ith a situati on requiri ng behav i oral ad j ust m e nt[8].H o wever,alt hough th i s certa i nly constitutes a benefici a l approac h,e m piricalwork in th i s fiel d re m ains rel at i vel y sparse[9].
2 R esu lts and D iscussi o n
T he attent i onal capac ity is assessed usi ng a classic letter cance ll at i on test[23].T asks of this type address the cogni t i ve co m ponents of selective and sustained attention that are undoubted l y of vast i m portance in everyday life[26 27]. In the test,subjects have to select and m ark as m any tar get sti m uli as possi b le i n a g i ven a m ount o f ti m e,and, hence,it also creates a certa i n load on the speed o f infor m ation processing.A utono m ic para m eters are recor ded under resting cond itions duri ng the exec ut i on of the task. O ne m ay assum e that features o f autono m ic control as sessed duri ng cognitive processi ng sho w the closest li nk to perf or m ance.On the other hand,on task m easures are i n fluenced by factors such as m enta l effort,e mo tiona l stress or sub jectively experienced task d ifficulty.I n contrast, base li ne m easures are free of these confounding variab les. T he fo ll ow ing predict i ons are m ade:1)T aking an i nverted u shaped assoc i at i on bet w een unspec ific sy m pathetic a rousal a nd m ental perf or m ance into account,a nd assum i ng an e xperm i ental situati on i n which sy mpathetic over act i v ity is unli kely to occ ur,an i nverse re l ationshi p bet ween RP I and atte ntional perfor mance may be expecte d;2)O n account of Por ges model[19],w e predict a positive correlati on bet ween the resting RSA and perfor mance;3)Our find i ngs on the baroreflex funct i on suggest t hat i ndividualsw ith an i ncreased BR S should e xhi b it poorer perfor mance[28];4)G i ve n the in verse associat i on bet ween oscillati ons in theM F ba nd a nd the m ental effort l oad,and supposing better perf or m ance i n the case of hi gher effort,t heM F po wer assessed duri ng task exe cut i on shou l d correlate ne gati vely w ith perfor mance;5)Con sideri ng Porges hypot hesis[19],we expect higher cardi ovas cular reactivity in indi v i duals w ith the hi gher rest i ng RS A;
6)Even though the available database is so me what controver sia,l the li kel y assoc i ation bet ween mental effort and auto no m ic reactivity suggests str onger react i v ity to be related to better perfor m ance.
3 Concl u sion
In this paper,w e develop a real tm i e,physiological data acquisiti on syste m f or educat i on assess m ent,wh i ch co m bi nes LabV I E W and w ireless sensor net wor ks,and w e fulfill the f unction of collecting,trans m itti ng,displ ay i ng and process i ng physiolog ical signals.In f uture w ork,we plan to add m ore f unctions to the ter m i nal display and si gnal process suc h as the e x traction of the special freque ncy spectru m s, and furt her psyc ho l og ical researches on the physi o l og ical si g nals fro m more subjects.F i nally,our subsequent consi dera t i on is to set up a more efficient m et hod to obtain physi o l ogi cal signals for assessing e motional states and mental reacti ons duri ng lear ning i n the classroo m.
References
[1]R a i nv ille P,Becha ra A,N aqv iN,et a.l Ba sic em o ti on s are
asso ciated w ith d isti nc t pa tterns o f cardio re s p ira t o ry acti v ity [J].Int J P sychophy sio l,2006,61(1):5 18.
[2]D uschek S,M uckentha ler M,W erner N,e t a.l R e l a tion
shi p s be t w een fea t ures o f aut onom ic card i o va scu l ar contro l and cogn iti v e perfo r m ance[J].B i o l o g ica l P sycho l o gy,
2009,81(2):110 117.
[3]S te mm ler G.T he autonom i c diffe renti a ti on o f em o ti ons re
v isited:conv erg en t and d iscri m i na te va lida tion[J].P sycho physi o l o gy,1989,26(6):617 631.
[4]Izard C E,M alate sta C Z.P erspec tives on e m o ti ona l deve l
op m ent[M].N ew Y o rk:W il ey,1987:494 554.
[5]H eeb D O.D r i v es and the CN S[J].P sycho l Rev,1955,
62(4):243 254.
[6]Y erkesR M,D o ds o n J D.T he re l a tion o f streng th o f sti m u
lus t o rapi d ity o f habit fo r m ati o n[J].Journa l o f Com pa ra tive N euro lo gy and P sycho log y,1908,18:459 482.
[7]L acey J I,L acey B C.Som e au t onom ic cen tra l nerv ous
sy stem i nterrela tionshi p s[C]//Physi o lo g ica l C o rre l a te s o f
E m o tion.N ew Y o rk:A cade m ic P ress,1970:205 227.
[8]O brist P A.C ardiova scula r psychophy sio log y:a per s pective
[M].N ew Y o rk:P lenu m Press,1981.
[9]H ansen A L,John sen B H,Thayer J F.V aga l i nfluence on
w o rking m e m o ry and a tten tion[J].Interna tiona l Journa l o f P sychophy sio l o g y,2003,48(3):263 274.
[10]L ev y M N,P appano A J.C a rdi o va scu l a r phy sio log y[M].
Phil adelphia:M o sby E lsev ier,2007.
[11]V an R oon,M u l de r L J M,A lthausM,e t a.l Introduc i ng a
baro reflex m ode l fo r st udy ing card i o vascular effects o f m en tal w orkload[J].P sychophysio l o gy,2004,41(6):961 981.
[12]D em bow s ky K,Se ll er H.F rom the hea rt to the bra i n:the
p sycho physi o lo gy o f c ircu l a tion bra i n i nteraction[M].
Frankfur:t Europ ischer V erlag der W issenschaf t en,1995:
35 60.
[13]R au H,E lber tT.P sy chophy si o logy o f arter i a l baro recepto rs
and t he eti o l og y o f hypertensi on[J].B i o l P sycho l,2001,
57(1/2/3):179 201.
[14]Z hang W e,i Ji ng Shenq,i G ui L i n,e t a.l Phy si o l og i ca l data
acqu isition sy ste m fo r educa ti on a ssess m ent usi ng w i re l e ss senso r net w o rk[C]//P ro ceed i ng s o f the5th Interna tiona l Co nference o n Info r m a ti on T echno l o gy and Applica ti on.
Shenzhen,Ch i na,2008:471 473.
[15]D i ng Fe,i Song G uangm i ng,Song A i g uo,Hom e contro l
s y ste m based on Z i gB ee w ire l e ss senso r net w o rks[J].Jour na l o f Sou t hea st U n i ver sity:Eng lis h Edition,2008,24(4):
420 423.
[16]Hong J H,K i m J M,C ha E J,et a.l A w ire less3 channel
ECG trans m issi on sy ste m usi ng PDA pho ne[C]//P roceed ings o f Interna tiona l Con ference on Converg ence Info r m a ti on Techno l o gy.Seou,l K o rea,2007:462 465.
[17]C erny M,Penhaker M.T he hom ecare and circad i an rhy t hm
[C]//P ro ceed i ng s o f t he5th Interna tiona l C onference on
Info rma tion T echno log y and A pplica ti o n.Shenzhen,Ch i na,
2008:245 248.
[18]C ar m en L opez C asado.N et w o rk arch itecture fo r g l o ba l b i o
m edical m on it o r i ng s e rv ice[C]//P ro ceeding s o f IEEE Eng i neer i ng in M ed ici ne and Bio log y27t h Annua l Co nference.
Shangha,i C hina.2005:2433 2436.
[19]Po rg es S W.Hear t rate va riab ilit y and dece l e ra tion as i nde
xe s o f reac tion ti m e[J].Journa l o f Exper i m enta l P sycho l o gy,1972,92(1):103 110.
[20]Po rter F L,Po rg es SW,M arshallR E.N e w bo rn pa i n cries
76Q i u W en ji ao,and Zhang Yongku i
and v ag a l tone :para lle l changes i n re s ponse t o c i rcu m c isi on
[J].Ch ild D ev,1988,59(2):495 505.[21]D e G ang iG A,L aur i e R S ,C ast e ll an J ,et a.l T rea t m ent o f
senso ry ,e m o tiona,l and a ttenti ona l proble m s i n regu l a t o ry d is o rdered i n fants [J].In fants and Young Chil dren,1991(3):9 19.
[22]D uschek S .E ssen ti a l hy po ten si on is accom panied by defic its
i n a tten ti on and w o rking m e m o ry[J].Beha vio ra lM edicine,2005,30(4):149 158.
[23]B acks R W ,Se ljo s K A.M etabo lic and cardio re s p ira t o ry
m easures o fm en t a l e ffo r:t t he e ffects o f leve l o f diff i culty i n w o rki ng m e m o ry task [J].Int J P sycho physi o l,1994,16(1):57 68.
[24]G endo ll a G H E ,W right R A.M o tiva tion i n soc i a l set
ti ng s :studies of effo r t related cardiov ascul a r arousa l[C ]//So cia lm o ti va ti o n:Consci o us a nd N onconsc i ou s P ro ce sses.
L o ndo n :C a m br i dge U n i v ersity Press ,2005:71 90.[25]L ee M i H ee ,Y ang G yunghye ,L ee H yo ung K ,i et a.l D e
ve lop m ent stress m on it o r i ng sy st em ba sed on personal d i g ital a ssistant(PDA )[C ]//P roceedi ng s o f t he 26t h Annua l Inter na tiona l C onfer ence o f the IEEE E M BS.San F rancisco,CA,U SA,2004:2364 2367.
[26]J o hnson A,Proc t o r R W.A ttention:theo ry and practice
[M ].Tho usand O aks ,CA,U SA:Sag e ,2004.[27]Po s ner M I ,R afa l R D.Co gn itive theo ries of a ttenti on and
t he rehab ilit a ti on o f atten tional defic its[C ]//N eu ro psycho lo gica l rehabilita ti on.Edinburgh :Churchill L i v i ng ston ,1987:182 201.
[28]Y a su m asu T,R ey es de l Pa s o G A,T akahara K,et a.l R e
duced baro reflex cardiac sen sitiv ity pred icts i ncreased co gni tive perfo r m ance[J].P sychophysi o l o gy,2006,43(1):41 45.
一种基于无线传感器网络的生理信号采集系统
邱文教 张永魁
(东南大学儿童发展与学习科学教育部重点实验室,南京210096)
摘要:提出了一种应用于课堂教育的无线生理采集系统,以了解学生在上课过程中的生理变化情况.系统中,反映学生的注意力和情绪状态的生理电信号可通过测量ECG 来获得.生物电信号采用200H z 的采样速率,并由Z i g Bee 协议进行无线传输.同时,节点嵌入了蓝牙技术以适应高采样速率和高带宽的传输要求.本系统可以同时对30个学生进行监测,并且给出了系统在教室执行监测任务的实验结果.最后探讨了无线传感器网络在教育领域的应用.
关键词:无线传感器网络;生理信号;教育中图分类号:TN92
77
Physiol og i cal s i gnal acqu isiti on syste m based on w i reless se nsor net w orks
南京航空航天大学 硕士学位论文 基于无线传感器网络的环境监测系统设计与实现 姓名：耿长剑 申请学位级别：硕士 专业：电路与系统 指导教师：王成华 20090101
南京航空航天大学硕士学位论文 摘要 无线传感器网络（Wireless Sensor Network，WSN）是一种集成了计算机技术、通信技术、传感器技术的新型智能监控网络，已成为当前无线通信领域研究的热点。 随着生活水平的提高，环境问题开始得到人们的重视。传统的环境监测系统由于传感器成本高，部署比较困难，并且维护成本高，因此很难应用。本文以环境温度和湿度监控为应用背景，实现了一种基于无线传感器网络的监测系统。 本系统将传感器节点部署在监测区域内，通过自组网的方式构成传感器网络，每个节点采集的数据经过多跳的方式路由到汇聚节点，汇聚节点将数据经过初步处理后存储到数据中心，远程用户可以通过网络访问采集的数据。基于CC2430无线单片机设计了无线传感器网络传感器节点，主要完成了温湿度传感器SHT10的软硬件设计和部分无线通讯程序的设计。以PXA270为处理器的汇聚节点，完成了嵌入式Linux系统的构建，将Linux2.6内核剪裁移植到平台上，并且实现了JFFS2根文件系统。为了方便调试和数据的传输，还开发了网络设备驱动程序。 测试表明，各个节点能够正确的采集温度和湿度信息，并且通信良好，信号稳定。本系统易于部署，降低了开发和维护成本，并且可以通过无线通信方式获取数据或进行远程控制，使用和维护方便。 关键词：无线传感器网络，环境监测，温湿度传感器，嵌入式Linux，设备驱动
Abstract Wireless Sensor Network, a new intelligent control and monitoring network combining sensor technology with computer and communication technology, has become a hot spot in the field of wireless communication. With the improvement of living standards, people pay more attention to environmental issues. Because of the high maintenance cost and complexity of dispose, traditional environmental monitoring system is restricted in several applications. In order to surveil the temperature and humidity of the environment, a new surveillance system based on WSN is implemented in this thesis. Sensor nodes are placed in the surveillance area casually and they construct ad hoc network automatieally. Sensor nodes send the collection data to the sink node via multi-hop routing, which is determined by a specific routing protocol. Then sink node reveives data and sends it to the remoted database server, remote users can access data through Internet. The wireless sensor network node is designed based on a wireless mcu CC2430, in which we mainly design the temperature and humidity sensors’ hardware and software as well as part of the wireless communications program. Sink node's processors is PXA270, in which we construct the sink node embedded Linux System. Port the Linux2.6 core to the platform, then implement the JFFS2 root file system. In order to facilitate debugging and data transmission, the thesis also develops the network device driver. Testing showed that each node can collect the right temperature and humidity information, and the communication is stable and good. The system is easy to deploy so the development and maintenance costs is reduced, it can be obtained data through wireless communication. It's easy to use and maintain. Key Words: Wireless Sensor Network, Environment Monitoring, Temperature and Humidity Sensor, Embedded Linux, Device Drivers
中英文资料对照外文翻译 基于网络共享的无线传感网络设计 摘要：无线传感器网络是近年来的一种新兴发展技术，它在环境监测、农业和公众健康等方面有着广泛的应用。在发展中国家，无线传感器网络技术是一种常用的技术模型。由于无线传感网络的在线监测和高效率的网络传送，使其具有很大的发展前景，然而无线传感网络的发展仍然面临着很大的挑战。其主要挑战包括传感器的可携性、快速性。我们首先讨论了传感器网络的可行性然后描述在解决各种技术性挑战时传感器应产生的便携性。我们还讨论了关于孟加拉国和加利 尼亚州基于无线传感网络的水质的开发和监测。 关键词：无线传感网络、在线监测 1.简介 无线传感器网络，是计算机设备和传感器之间的桥梁，在公共卫生、环境和农业等领域发挥着巨大的作用。一个单一的设备应该有一个处理器，一个无线电和多个传感器。当这些设备在一个领域部署时，传感装置测量这一领域的特殊环境。然后将监测到的数据通过无线电进行传输，再由计算机进行数据分析。这样，无线传感器网络可以对环境中各种变化进行详细的观察。无线传感器网络是能够测量各种现象如在水中的污染物含量，水灌溉流量。比如，最近发生的污染涌流进中国松花江，而松花江又是饮用水的主要来源。通过测定水流量和速度，通过传感器对江水进行实时监测，就能够确定污染桶的数量和流动方向。 不幸的是，人们只是在资源相对丰富这个条件下做文章，无线传感器网络的潜力在很大程度上仍未开发，费用对无线传感器网络是几个主要障碍之一，阻止了其更广阔的发展前景。许多无线传感器网络组件正在趋于便宜化（例如有关计算能力的组件），而传感器本身仍是最昂贵的。正如在在文献[5]中所指出的，成功的技术依赖于
基于无线传感器网络的桥梁安全检测系统 摘要 根据桥梁监测无线传感器网络技术的桥梁安全监测系统，以实现方案的安全参数的需要；对整个系统的结构和工作原理的节点集、分簇和关键技术，虽然近年来在无线传感器网络中，已经证明了其潜在的提供连续结构响应数据进行定量评估结构健康，许多重要的问题，包括网络寿命可靠性和稳定性、损伤检测技术，例如拥塞控制进行了讨论。 关键词：桥梁安全监测；无线传感器网络的总体结构；关键技术 1 阻断 随着交通运输业的不断发展，桥梁安全问题受到越来越多人的关注。对于桥梁的建设与运行规律，而特设的桥梁检测的工作情况，起到一定作用，但是一座桥的信息通常是一个孤立的片面性，这是由于主观和客观因素，一些桥梁安全参数复杂多变[1]。某些问题使用传统的监测方法难以发现桥梁存在的安全风险。因此长期实时监测，预报和评估桥梁的安全局势，目前在中国乃至全世界是一个亟待解决的重要问题。 桥梁安全监测系统的设计方案，即通过长期实时桥跨的压力、变形等参数及测试，分析结构的动力特性参数和结构的评价科关键控制安全性和可靠性，以及问题的发现并及时维修，从而确保了桥的安全和长期耐久性。 近年来，桥梁安全监测技术已成为一个多学科的应用，它是在结构工程的传感器技术、计算机技术、网络通讯技术以及道路交通等基础上引入现代科技手段，已成为这一领域中科学和技术研究的重点。 无线传感器网络技术，在桥梁的安全监测系统方案的实现上，具有一定的参考价值。 无线传感器网络（WSN）是一种新兴的网络科学技术是大量的传感器节点，通过自组织无线通信，信息的相互传输，对一个具体的完成特定功能的智能功能的协调的专用网络。它是传感器技术的一个结合，通过集成的嵌入式微传感器实时监控各类计算机技术、网络和无线通信技术、布式信息处理技术、传感以及无线发送收集到的环境或各种信息监测和多跳网络传输到用户终端[2]。在军事、工业和农业，环境监测，健康，智能交通，安全，以及空间探索等领域无线传感器网络具有广泛应用前景和巨大的价值。 一个典型的无线传感器网络，通常包括传感器节点，网关和服务器，如图1
无线传感器网络概述 1科技发展的脚步越来越快，人类已经置身于信息时代，作为信息获取最重要和最基本的技术——传感器技术，得到了极大的发展。 2目前无线网络可分为两种:一种是有基础设施的网络,需要固定基站,例如我们使用的手机，属于无线蜂窝网，它就需要高大的天线和大功率基站来支持，基站就是最重要的基础设施；另外，使用无线网卡上网的无线局域网，由于采用了接入点这种固定设备，也属于有基础设施网。 另一类是无基础设施网，又称为无线Ad hoc网络,节点是分布式的，没有专门的固定基站。 无线Ad hoc网络又可分为两类: 一类是移动Ad hoc网络(Mobile Ad hoc Network,简称MANET)，它的终端是快速移动的。一个典型的例子是美军101空降师装备的Ad hoc网络通信设备，保证在远程空投到一个陌生地点之后，在高度机动的装备车辆上仍然能够实现各种通信业务，而无需借助外部设施的支援。另一类就是我们讲的无线传感器网络,它的节点是静止的或者移动很慢。 3传感器网络的标准定义是这样的： 传感器网络是大量的静止或移动的传感器以自组织和多跳的方式构成的无线网络，其目的是协作地感知、采集、处理和传输网络覆盖地理区域内感知对象的监测信息，并报告给用户。它的英文是Wireless Sensor Network, 简称WSN。 如图所示，大量的传感器节点将探测数据，通过汇聚节点经其它网络发送给了用户。 在这个定义中，传感器网络实现了数据采集、处理和传输的三种功能，而这正对应着现代信息技术的三大基础技术，即传感器技术、计算机技术和通信技术。 4它们分别构成了信息系统的“感官”、“大脑”和“神经”三个部分。因此说，无线传感器网络正是这三种技术的结合，可以构成一个独立的现代信息系统。 5第一阶段：最早可以追溯二十世纪70年代越战时期使用的传统的传感器系统。当年美越双方在密林覆盖的“胡志明小道”进行了一场血腥较量，这条道路是胡志明部队向南方游击队源源不断输送物资的秘密通道，美军曾经绞尽脑汁动用航空兵狂轰滥炸,但效果不大。后来，美军投放了2万多个“热带树”传感器。所谓“热带树”实际上是由震动和声响传感器组成的系统，它由飞机投放，落地后插入泥土中，只露出伪装成树枝的无线电天线，因而被称为“热带树”。只要对方车队经过，传感器探测出目标产生的震动和声响信息，自动发送到指挥中心，美机立即展开追杀，总共炸毁或炸坏4.6万辆卡车。 这种早期使用的传感器系统的特征在于传感器节点只产生探测数据流，没有计算能力，并且相互之间不能通信。 6第二阶段是二十世纪80年代至90年代之间。 主要是美军研制的分布式传感器网络系统、海军协同交战能力系统、远程战场传感器系统等。这种现代微型化的传感器具备感知能力、计算能力和通信能力。因此在1999年，商业周刊将传感器网络列为21世纪最具影响的21项技术之一。 7第三阶段：21世纪开始至今。也就是本课开始介绍的911事件发生之后。这个阶段的传感器网络技术特点在于网络传输自组织、节点设计低功耗。 除了应用于情报部门反恐活动以外，在其它领域更是获得了很好的应用，所以2002年美国国家重点实验室－－橡树岭实验室提出了“网络就是传感器”的论断。 由于无线传感网在国际上被认为是继互联网之后的第二大网络，2003年美国《技术评论》杂志评出对人类未来生活产生深远影响的十大新兴技术，传感器网络被列为第一。 在现代意义上的无线传感网研究及其应用方面，我国与发达国家几乎同步启动，它已经成为我国信息领域位居世界前列的少数方向之一。在2006年我国发布的《国家中长期科学
1武警部队监控平台架构介绍与设计 1.1监控系统的系统结构 基站监控系统的结构组成如上图所示，主要由三个大的部分构成，分别是监控中心、监控站点、监控单元。整个系统从资金、功能以及方便维护性出发，我们采用了干点加节点方式的监控方法。 监控中心（SC）：SC的定义是指整个系统的中心枢纽点，控制整个分监控站，主要的功能是起管理作用和数据处理作用。一般只在市级包括（地、州）设置相应的监控中心，位置一般在武警部队的交换中心机房内或者指挥中心大楼内。 区域监控中心（SS）：又称分点监控站，主要是分散在各个更低等级的区县，主要功能是监控自己所负责辖区的所有基站。对于固话网络，区域监控中心的管辖范围为一个县/区；移动通信网络由于其组网不同于固话本地网，则相对弱化了这一级。区域监控中心SS的机房内的设备配置与SC的差不多，但是不同的是功能不同以及SS的等级低于SC,SS的功能主要是维护设备和监控。 监控单元（SU）：是整个监控系统中等级最低的单元了，它的功能就是监控并且起供电，传输等等作用，主要由SM和其他供电设备由若干监控模块、辅助设备构成。SU侧集成有无线传感网络微设备，比如定位设备或者光感，温感设备等等。 监控模块（SM）：SM是监控单元的组成部分之一，主要作用监控信息的采集功能以及传输，提供相应的通信接口，完成相关信息的上传于接收。
2监控系统的分级管理结构及监控中心功能 基站监控系统的组网分级如果从管理上来看，主要采用两级结构：CSC集中监控中心和现场监控单元。CSC主要设置在运营商的枢纽大楼，主要功能为数据处理，管理远程监控单元，对告警信息进行分类统计，可实现告警查询和存储的功能。一般管理员可以在CSC实现中心调度的功能，并将告警信息进行分发。而FSU一般针对具体的某一个基站，具体作用于如何采集数据参数并进行传输。CSC集中监控中心的需要对FSU采集的数据参数进行报表统计和分析，自动生产图表并为我们的客户提供直观，方便的可视化操作，为维护工作提供依据，维护管理者可以根据大量的分析数据和报表进行快速反应，以最快的速度发现网络的故障点和优先处理点，将人力资源使用在刀刃上。监控中心CSC系统的功能中，还有维护管理类，具体描述如下： 1）实时报警功能 该系统的报警功能是指发现机房里的各种故障后，通过声音，短信，主界面显示的方式及时的上报给操作者。当机房内的动力环境，空调，烟感，人体红外等等发生变量后，这些数据通过基站监控终端上传到BTS再到BSC。最后由数据库进行分类整理后存储到SQLSEVRER2000中。下面介绍主要的几种报警方式： 2)声音报警 基站发生告警后，系统采集后，会用声卡对不一样的告警类别发出对应的语音提示。比如：声音的设置有几种，主要是以鸣叫的长短来区分的。为便于引起现场维护人员的重视紧急告警可设置为长鸣，不重要的告警故障设置为短鸣。这样一来可以用声音区分故障的等级，比方某地市的中心交换机房内相关告警声音设置，它的开关电源柜当平均电流达到40AH的时候，提示声音设置为长鸣，并立即发生短信告警工单。如果在夜晚机房无人值守的情况下：
无线传感器网络的应用与影响因素分析 摘要：无线传感器网络在信息传输、采集、处理方面的能力非常强。最初，由于军事方面的需要，无线传感网络不断发展，传感器网络技术不断进步，其应用的范围也日益广泛，已从军事防御领域扩展以及普及到社会生活的各个方面。本文全面描述了无线传感器网络的发展过程、研究领域的现状和影响传感器应用的若干因素。关键词：无线传感器网络；传感器节点；限制因素 applications of wireless sensor networks and influencing factors analysis liu peng (college of computer science,yangtze university,jingzhou434023,china) abstract:wireless sensor networks in the transmission of informa- tion,collecting,processing capacity is very strong.initially,due to the needs of the military aspects of wireless sensor networks,the continuous development of sensor network technology continues to progress its increasingly wide range of applications,from military defense field to expand and spread to various aspects of social life.a comprehensive description of the development
一、课题研究目的 针对目前中国的交叉路口多，车流量大，交通混乱的现象研究一种控制交通信号灯的基于无线传感器的智能交通系统。 二、课题背景 随着经济的快速发展，生活方式变得更加快捷，城市的道路也逐渐变得纵横交错，快捷方便的交通在人们生活中占有及其重要的位置，而交通安全问题则是重中之重。据世界卫生组织统计，全世界每年死于道路交通事故的人数约有120 万，另有数100 万人受伤。中国拥有全世界1. 9 %的汽车，引发的交通事故占了全球的15 % ，已经成为交通事故最多发的国家。2000 年后全国每年的交通事故死亡人数约在10 万人，受伤人数约50万，其中60 %以上是行人、乘客和骑自行车者。中国每年由于汽车安全方面所受到的损失约为5180 亿(人民币)，死亡率为9 人/ 万·车，因此，有效地解决交通安全问题成为摆在人们面前一个棘手的问题。 在中国，城市的道路纵横交错，形成很多交叉口，相交道路的各种车辆和行人都要在交叉口处汇集通过。而目前的交通情况是人车混行现象严重，非机动车的数量较大，路口混乱。由于车辆和过街行人之间、车辆和车辆之间、特别是非机动车和机动车之间的干扰，不仅会阻滞交通，而且还容易发生交通事故。根据调查数据统计，我国发生在交叉口的交通事故约占道路交通事故的1/ 3，在所有交通事故类型中居首位，对交叉口交通安全影响最大的是冲突点问题，其在很大程度上是由于信号灯配时不合理(如黄灯时间太短,驾驶员来不及反应)，以及驾驶员不遵循交通信号灯，抢绿灯末或红灯头所引发交通流运行的不够稳定。随着我国经济的快速发展，私家车也越来越多，交通控制还是延续原有的定时控制，在车辆增加的基础上，这种控制弊端也越来越多的体现出来，造成了十字交叉路口的交通拥堵和秩序混乱，严重的影响了人们的出行。智能交通中的信号灯控制显示出了越来越多的重要性。国外已经率先开展了智能交通方面的研究。 美国VII系统(vehicle infrastructure integration)，利用车辆与车辆、车辆与路边装置的信息交流实现某些功能，从而提高交通的安全和效率。其功能主要有提供天气信息、路面状况、交叉口防碰撞、电子收费等。目前发展的重点主要集中在2个应用上: ①以车辆为基础; ②以路边装置为基础。欧洲主要是CVIS 系统(cooperative vehicle infrastructure system)。它有60 多个合作者，由布鲁塞尔的ERTICO 组织统筹，从2006 年2 月开始到2010年6月，工作期为4年。其目标是开发出集硬件和软件于一体的综合交流平台，这个平台能运用到车辆和路边装置提高交通管理效率，其中车辆不仅仅局限于私人小汽车，还包括公共交通和商业运输。日本主要的系统是UTMS 21 ( universal traffic management system for the 21st century , UTMS 21)。是以ITS 为基础的综合系统概念,由NPA (National Police Agency) 等5个相关部门和机构共同开发的，是继20 世纪90 年代初UTMS 系统以来的第2代交通管理系统，DSSS是UTMS21中保障安全的核心项目，用于提高车辆与过街行人的安全。因此，从国外的交通控制的发展趋势可以看出，现代的交通控制向着智能化的方向发展，大多采用计算机技术、自动化控制技术和无线传感器网络系统，使车辆行驶和道路导航实现智能化，从而缓解道路交通拥堵，减少交通事故，改善道路交通环境，节约交通能源，减轻驾驶疲劳等功能，最终实现安全、舒适、快速、经济的交通环境。
Journal of Southeast U niversity (Eng lish Edition) V o.l 26,N o .1,pp .73-77M ar .2010 I SSN 1003 7985 Physiological signal acquisition syste m based on w ireless sensor net works Q iuW enjiao Zhang Y ongkui (K ey L abo ra t o ry o f Ch ild D eve l opm ent and L earn i ng Sc ience o fM i n istry o f Education ,Southea st U n i v ersity ,N anji ng 210096,Ch i na) Abstr act :B ase d on w ireless sensor net w orks ,a physi o l ogical si gnal acquisiti on syste m is pr oposed .The syste m is use d i n classroo m education in order t o understand t he physi o l ogical c hanges i n t he students .I n t he s y ste m,the biolog i cal electrical si gnal relate d to student atte n ti on a nd e m oti on states ca n be m easur ed by electrocar d i ogr aphy signals .The b i oel ectri cal signal is digitali zed at a 200H z s a m p ling rate and is tra n s m itted by t he Z ig B ee protoc o.l S i m u lta neously ,t he B l uet ooth technology is als o e m be dde d i n the nodes so as to m eet the high sa m pli ng rate a nd the high ba nd w i d t h tra n s m issi on .The syste m can i m p l e m ent them on it o ri ng tas k s for 30students ,and t he experi m ental resu lts of usi ng t he syste m i n t he cl assroo m are propose d .Finall y ,t he a pplicati ons of w irel ess se n s or net w orks used in e ducati on is als o d iscussed .K ey w or ds :w ir eless sensor net w or k ;physi o l ogical si gna;l e du cati on Recei ved 2009 07 20.Biographies :Q i u W en ji ao (1969 ),m ale ,graduate ;Zh ang Y on gku i (corres ponding au t ho r),m ale ,do ctor ,ass ociat e pro fess or ,yzhangb @s https://www.doczj.com/doc/215525574.html, .cn . Foundati on ite m:The N ati ona lNatural S ci en ce Foundation of Ch i na(No.60775057). C itati on :Q iu W en ji ao,Zh ang Y on gku.i Phy si o l og i ca l signa l acqu isition s y st e m based on w i rel ess sen s or net w ork s[J].J ournal o f SoutheastU niver sit y (E ngli sh Ed iti on ),2010,26(1):73 77. A lthough the attent i on state and e mot i ona l state of stude n ts dur i ng the lear n i ng process belong to the psyc holog ica l do m a i n,it can be i ndirectly m easured by physi o l og i cal signals ,suc h as e lectr ocard i ography si gnals and pulse signals .Students and teachers m ental states of attention and e mo ti on in the classroo m m ay be chang i ng dur i ng teach i ng progress ,wh ich can physi o l og i cally acti vate the sy m pathetic and parasy mpathetic division o f the autono m ic nervous syste m (AN S )[1 2] .T hese m easurable physi o l og i cal signals can be recorded for the analyses of psyc holog ica l ar ousal of social re w ar ds and punish m ents ,such as posit i ve feedbac k by the teacher s praises or higher exa m i nat i on grades ,even the a mount of a scholarship ,al though the arousal of the autono m ic nervous syste m reac t i ons m ay be a co m plex i ndirect relationship to e m o t i on [3 4] .Interact i ons bet w een states of the autono m ic nerv ous syste m and cognit i ve perfor m ance have a long trad ition of being a top ic of psycho log ical research .C lassic concepts fro m mo tivat i onal psycho logy have suggested an i nverted u shaped association bet w een unspec ific activat i on and m en tal funct i oning [5 6] .A ccor d i ng to this ,the best funct i onal condit i ons are expected atm idrange arousa,l and both over ar ousa l and under arousal are acco m panied by declines in perf or m ance .Cardiovasc u lar psychophysiology has also contributed to this li ne of research ,the respective models re l at i ng changes in card i ovascular act i v ity to facilitation, i nh i b it i on of i nfor m ation processi ng [7] or ener get icm ob iliza t i on o f the organis m when faced w ith a situat i on requ iri ng behav i oral ad j ust m ent [8] .H o w ever ,although this certai n ly const itutes a benefic i a l appr oach ,e m p irical work i n th is f i e l d re m a i ns re lati vely sparse [9] .Both the sy m pathetic syste m and the parasy mpathetic syste m contri bute to cardi ovascular regulat i on [10] .Sy mpathetic i n fl uences are trans m itted through efferent fibres to the si nus node ,the m yo cardiu m and the vascularm usc u lature ,and their activati on leads to an i ncrease i n heart rate ,cardiac contract ility and vascular tone .Parasy mpathetic i nfl ue nces arew i de l y ,but not co mpletely ,restri cted to the m odulat i on of heart rate through i nhibiting sinus node act i v ity .I n addition ,the cardiac baroreflex is involved .I n th i s negative feedbac k loop ,c han ges i n the act i vity of the arterial baroreceptors due to fl uctua tions i n b l ood pressure are responded w ith co m pensatory changes i n heart rate and contract ility .A co mplex net work of brai n ste m un its subserve cardi ovascular autono m ic contro,l e .g .,the nucleus of the so litar y tract(NT S),the dorsalm otor nucle us(DMN ),the nucleus a mbiguous(NA )and the rostral ventrolateral medulla(RVL M )[11] .B ilateral direct and i ndi rect c onnecti ons ex ist bet w een this net work and cortical areas ,which for m an m i portant li nk bet wee n cardi ovascular regulation and cogn ition [12-13] .The present study am i s at in vest i gat i ng relationsh i ps a mong features of sy m pathetic ,para sy mpathetic and bar oreflex car d i ovascular control and atten tional perfor mance . To collect these physi ca l and mental states data i n real tm i e and objectivel y ,a hybrid w ireless sensor net w ork is desi gned as the subjects of a teac her and st ude nts are mob ile .For m edical and ho m e usage ,li ce nse free IS M (i ndustr y ,sci ence ,m edical)radio frequency(RF )o f 2 4G H z Z i gBee w ire l ess sensor node technology is usef u l [14 18] . 1 Syste m D escripti o n A s a secondary ai m ,the study i nvestigates i nter i nd i v i d ual differences i n task i nduced cardiovascular m odula t i ons .Porges [19] postulated an associat i on bet w een resti ng cardiac vagal tone and the ex tent o f card i ovascular react i v i ty .Th is is consistent w ith stud i es that have revealed m ore pronounced heart rate responses to var i ous st i m u li i n chil dren and adults w ith higher baseline heart rate variabili ty [19 21].Cardiovascular reacti v ity to cogniti ve de m a nds m ay also rel ate to task perfor m ance .Duschek [22] found a positive correlat i on bet wee n systo lic and diastolic b l ood pressure in creases duri ng the executi on o f five attenti on tasks a nd the perfor mance on each o f the m.I n i nfants ,greater decreases of RS A duri ng m ental testing are related to higher f unct i onal levels [21] .Inter i ndividual differences in cardiovasc ular mod ulation possi bly reflect different degrees of autono m ic adj ust
无线传感器网络的研究现状及发展 默认分类 2008-06-12 18:19:20 阅读910 评论0 字号：大中小 摘要：无线传感器网络(WSN>综合了传感器技术、微电子机械系统(MEMS>嵌入式计算技术．分布式信息处理技术和无线通信技术，能够协作地实时感知、采集、处理和传输各种环境或监测对象的信息．具有十分广阔的应用前景，成为国内外学术界和工业界新的研究领域研究热点。本文简要介绍了无线传感器网络的网络结构、节点组成，分析了无线传感器网络的特点及其与现有网络的区别。进而介绍现有无线传感器网络中的MAC层技术、路由技术、节点技术和跨层设计等关键技术。最后展望无线传俄器网络的应用和发展并指出关键技术的进步将起到决定性的促进作用。 关键词：无线传感器网络节点 MAC层路由协议跨层设计 Abstract: Wireless sensor network (WSN> is integration of sensor techniques, Micro-Electro-Mechanical Systems, embedded computation techniques, distributed computation techniques and wireless communication technique. They can be used for sensing, collecting, processing and transferring information of monitored objects for users. As a new research area and interest hotspot of academia and industries, Wireless Sensor Network(WSN> has a wide application future. This paper briefly introduced the wireless sensor network of networks, nodes, the analysis of the characteristics of wireless sensor networks and the differences wih the existing networks. And the MAC layer technology, routing technology, joint cross-layer design technology and key technology are introduced . At last the prospects of wireless sensor network are discussed in this article. Key Words: Wireless Sensor Network, node, MAC, routing protocol, Cross-layer design 一、概述 随着通信技术、嵌入式计算技术和传感器技术的发展进步，包括微电子机械系统 文章编号:1004-9037(2009)02-0254-05 基于无线传感网络的大型结构健康监测系统 尚 盈 袁慎芳 吴 键 丁建伟 李耀曾 (南京航空航天大学智能材料与结构航空科技重点实验室,南京,210016) 摘要:针对大型碳纤维复合材料机翼盒段壁板结构,实现了基于无线传感网络的多点应变结构健康监测系统,采用自组织竞争神经网络成功判别了集中载荷模拟的损伤位置。本系统由传感采集子系统、无线传感网络子系统和终端监控子系统三部分组成。为了降低系统网络功耗及成本,提高系统的稳定性和可靠性,改善传感网络的实时性和同步性,设计了可直接配接无线传感网络节点的低功耗多通道应变传感器信号调理电路和基于无线传感网络的层次路由协议,开发了多通道应变数据采集、网络簇头转发和中继节点接收等主要软件模块。实验证明,相比于传统有线的监测方法和数据采集系统,基于无线传感网络的结构健康监测系统具有负重轻、成本低、易维护和搭建移动方便等优点。 关键词:无线传感网络;结构健康监测;层次路由协议;自组织竞争网络中图分类号:T P2;T P9 文献标识码:A 基金项目:国家“八六三”高技术研究发展计划(2007AA 032117)资助项目;国家自然科学基金(60772072,50420120133)资助项目;航空基金(20060952)资助项目。 收稿日期:2007-09-05;修订日期:2008-04-17 Large -Scale Structural Health Monitoring System Based on Wireless Sensor Networks S hang Ying ,Yuan Shenf ang ,Wu J ian ,Ding J ianw ei ,L i Yaoz eng (T he A ero nautic Key La bo rat or y o f Smart M ater ial and Str uct ur e,N anjing U niv ersit y o f Aer onautics and A str onautics,N anjing,210016,China) Abstract :Aimed at the large-scale structure and anisotropy nature o f the carbon fiber compos-ite material w ing box ,a large-scale structural health m onitoring system based on w ireless sen-sor netw orks is presented .A kind of artificial neural netw ork is designed to distinguish the damag e locatio n simulated by the co ncentrated load .The sy stem co nsists o f the sensor data ac-quisition,the w ireless sensor netw or ks,and the terminal monitoring sub-sy stem s.To im pro ve the performance o f the system ,the signal conditio ning circuit and the hierarchical routing pro -to col are designed based o n w ireless sensor netw orks ,the prog rams of data acquisition and Sink node are ex ploited.Experimental result pro ves that the system has advantag es of flexibili-ty o f deplo yment,low maintenance and deploym ent costs . Key words :w ir eless senso r netw or ks ;str uctural health monitoring ;hierarchical routing ;self -org anizing com petitive netw o rk 引 言 结构健康监测技术是采用智能材料结构的新概念,利用集成在结构中的先进传感/驱动元件网络,在线实时地获取与结构健康状况相关的信息(如应力、应变、温度、振动模态、波传播特性等),结 合先进的信号信息处理方法和材料结构力学建模 方法,提取特征参数,识别结构的状态,包括损伤,并对结构的不安全因素在其早期就加以控制,以消除安全隐患或控制安全隐患的进一步发展,从而实现结构健康自诊断、自修复、保证结构的安全和降低维修费用[1]。 无线传感网络节点具有局部信号处理的功能, 第24卷第2期2009年3月数据采集与处理Jour nal of D ata A cquisition &P ro cessing Vo l.24N o.2M a r.2009基于无线传感网络的大型结构健康监测系统_尚盈
相关主题
文本预览