V Iteratioal Forum for Youg cietists "pace Egieerig" Multisesor trasducer based o a parallel fiber optic digital-to-aalog coverter Vladimir Grechishikov 1, Olga Teryaeva 1,*, ad Vyacheslav Aiev 1 1 amara Natioal Research iversity, 44386 amara, Russia Abstract. Cosidered possibility of creatig a multisesory iformatio coverter (MPI) based o ew fiber-optic fuctioal elemet-digital-toaalog () fiber optic coverter. The use of fiber-optic provides jammig immuity combied with low weight ad cost of idicators.because of that MPI scheme was developed based o parallel fiber-optic (Russia Federatio Patet 157416). We came up with a euatio for parallel fiber-optic. A eleborate geeral mathematical model of the proposed coverter. Developed a method for reducig coversio errors by placig the trasfer fuctio betwee i ad i + 1 uatizatio levels. By usig this model it allows you to obtai reliable iformatio about the techical capabilities of a coverter without the eed for costly experimets. 1 Itroductio Fiber-optic digital multisesor trasducers (MTs) are a class of multi-iput biary sigal trasducers desiged for collectio of data o threshold parameters of the cotrolled object, their trasmissio over a shared chael ad restoratio at the output i a form suitable for cotrol ad moitorig systems applicatio. The mai competitive advatage of trasducers of this class compared with their electroic couterparts is evidet i desig of multivariable cotrol systems of spatially distributed objects operatig uder strog electromagetic fields, as well as i explosive ad evirometally hazardous eviromets. uch operatio coditios are typical for cotrol systems used for space purposes, covetioal ad uclear power egieerig, chemical idustry ad other fields. The mai reuiremets of MTs i these coditios are: immuity to electromagetic iterferece, zero risk of abormal spark formatio, high umber of moitored parameters ad accuracy of reproductio of the iput sigal values, high performace typical for electrically passive cotrol systems with peumatic ad hydraulic actuatig uits. The problems of developmet of MTs ad their compoets are expouded i patet literature ad research work of Russia ad foreig authors amog them V.M. Grechishikov, V.A. Zelesky, O.A. Kulish, G.I. Leoovich, J. H. Hog, C. M. Verber, I. A. Galto, Y-K. Che, A. Leve whose work is highlighted [1, ]. * Correspodig author: aeva_olga@ibox.ru The Authors, published by EDP cieces. This is a ope access article distributed uder the terms of the Creative Commos Attributio Licese 4. (http://creativecommos.org/liceses/by/4./).
V Iteratioal Forum for Youg cietists "pace Egieerig" Parallel FO-based MT Examples of MT based o parallel digital to aalog fiber optic coverter are discussed i sectio [3, 4]. I the existig devices there are sigificat errors i geeralizatio of uatized sigal at the output of the due to ueveess of optical radiatio eterig ito the chaels limitig metrological characteristics of the device as a whole I order to address this problem, the modified MT desig was proposed [1]. The problem of ouiformity of optical iput i MT described above is solved by replacig fixed-value resistors i the LED supply circuit with trimmig resistors, ad supplyig offset.5v of uatizatio icremet of FO output parameter to the iput of the amplifier. A diagram of MT is show i Figure 1. MT circuit icludes a erece voltage source 1, a four-chael biary coverter uit (BC), a FO, a commo fiber optic light guide 14, a photo detector 15, a amplifier 16, a 17. Each chael of BC icludes a electroic key, a trimmig resistor 3 ad LED 4. FO icludes trasmittig optical fibers 5, trasmittig spherical leses 6, weightig elemets 7-1, receivig spherical leses 11, receivig optical fibers 1, a Y- coupler 13. BC FO Fig. 1. Diagram of parallel FO-based MT. MT operates as follows. Whe keys are closed, REF 1 sets the level of direct optical radiatio at the output of LED 4. Optical radiatio flows through the trasmittig optical fiber 5 ad the trasmittig spherical les 6 to weightig elemets 7-1. They provide weightig of each light flux i accordace with the law i. The each of the light flows is trasmitted to the Y-coupler through the receivig spherical les 11 ad the receivig optical fiber 1. Optical sigals are geerated ad trasmitted to the fial positio of the actuatig mechaism. Optical sigal from the output of the Y-coupler is trasmitted through the commo optical fiber 14 to the photodetector 15. The the sigal is amplified at the amplifier 16 ad receives offset voltage from the secod output of REF. po amplificatio ad offsettig, the voltage is supplied to the iput of where it is coverted ito codea i that explicitly correspods to termial positios of actuators x. i 3 Geeralized mathematical model of a parallel FO-based MT A mathematical model of a parallel FO was derived i [4, 5]. For output sigal to match iput sigal, it is ecessary for uatizatio icremet ( ) to match the value of the uatizatio icremet ( ):. Give that
V Iteratioal Forum for Youg cietists "pace Egieerig", ad ( 1) px, (1) where is erece voltage, is discharge, p is step of uatizatio of the aalog output. We obtai: ( 1) px, pr ( 1). () A group of expressios below follows from (): R ; p p R ;. (3) pr The euality ca be obtaied by variatio of back resistace, optical power level at the output of the BC or chagig of photodevice sesitivity. As show i Figure, it is evidet that the scale of trasfer characteristic coicides with the levels of uatizatio, ad the slightest sigal istability ca lead to sigificat errors i operatio. To avoid these, it is ecessary to shift off up by a amout eual to:,5 * off (parameter ). The trasformed offset parameter has output uatizatio levels betwee i ad i 1 of uatizatio levels (see Fig. 4). This provides oe-to-oe correspodece betwee the output code of ( a, a1,..., a 1) ad the iput code of the data collectio device ( x, x1,..., x 1) set by the positio of the. IN OT OT IN Fig.. Parameters of coversio provided by FO ad. Through these operatios, the followig oe-to-oe correspodece is achieved: { xi} { ai} The sigal at the output of the amplifier: ( x) R p N[{ x}] i i off (4) 3
V Iteratioal Forum for Youg cietists "pace Egieerig" where p is uatizatio iterval of the aalog output sigal; i is the coefficiet of eergy losses i fiber-optic commuicatio lies; is the sesitivity of the detector; R off is back resistace of a trasducer trasformig photoelectric curret ito voltage; is zero offset voltage; N[{ xi}] P *. Let us assume to be voltage-to-code coverter (VCC) with parallel coversio [6]. The output sigal of i comparator of VCC uit ca be set by a sigle fuctio with the followig form: e m m 1 at ( x) off ; m при ( x) off, (5) 1 where is erece voltage, m. sig Boolea algebra rules, we ca obtai expressios for the values of bit digits of the output code as follows: a ( x) b ( x) b ( x) b ( x) b ( x); 1 3 5 7 a ( x) b ( x) b ( x) b ( x) b ( x); 1 3 6 7 a ( x) b ( x) b ( x) b ( x) b ( x), 4 5 5 7 (6) bi( x) ei( x) ei 1( x); where where i1,...,( m 1). bm( x) em( x) e ( x), Thus, the resultig mathematical model makes it possible for us to ivestigate a set of metrological characteristics of optical s, takig ito accout deviatios of desig parameters of the trasducer ( ФП, RОС, i, p N[{ xi }], СМ ) from the omial value, i accordace with the procedures set forth i [6]. 4 Coclusio We propose the origial desig of parallel FO-based MT for cotrol systems with electrically passive peumatic ad/or hydraulic actuators. A euatio for FO coversio was obtaied, takig ito accout the passive ature of its optical circuit. We cosidered a method to reduce the error of coversio by placig trasfer factor betwee i ad i 1 uatizatio levels. A geeralized mathematical model of the proposed data collectio device was developed to display data trasductio processes i its aalog, aalog-to-digital ad digital fuctioal elemets. Applicatio of this model makes it possible to obtai reliable iformatio o the techical capabilities of the described trasducer with o eed for costly physical experimets. Refereces 1.. Chi-Chog Tseg, Patet 398543 (1974). V.M. Grechishikov, O.V. Terjaeva, RF Patet 157416 (15) (i Russia) 4
V Iteratioal Forum for Youg cietists "pace Egieerig" 3. V.M. Grechishikov, V.G. Domrachev, O.V. Teryaeva, A.A. Yudi, Measuremet Techiues 57, 139 (15) 4. V.M. Grechishikov, O.V. Teryaeva, Russia Aeroautics 59, 46 (16) 5. V.M. Grechishikov, V.G. Domrachev, I.V. Retiskaya, O.V. Teryaeva, Measuremet Techiues 58, 117 (16) 6. V.M. Grechishikov, Metrologiya i radioizmereiya (Publishig House of amara Natioal Research iversity, 7) (i Russia) 5