Research on the Optimal Sensor Placement of Vehicle Control System Based on Bode Sensitivity Function

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1 enor & Trnducer 4 by IF Publihing. L. Reerch on the Optiml enor Plcement of Vehicle ontrol ytem Bed on Bode enitivity Function hunqing Yu Hongjie heng Hongqing HouQin Mio Xi n Reerch Intitute of hi-tech Hongqing Town Xi n 75 P. R. hin Tel.: E-mil: 69@63.com Received: 7 ugut 4 /ccepted: 3 October 4 /Publihed: 3 November 4 btrct: In lluion to the optiml enor plcement problem for the condition monitoring nd fult dignoi of the vehicle control ytem in the wepon ytem the optiml enor plcement theory bed on Bode enitivity function i dopted to plce enor. imultion experiment i crried out through imultion model which h two-circuit cloed loop ytem nd the reult indicte the rtionlity of chooing detection point ccording to enitivity function mplitude. Finlly the bic cheme nd intructive rule on enor plcement of the vehicle control ytem re propoed. The cheme cn optimize the enor plcement nd obtin the rich informtion of the ytem t low cot. By thi wy the effect of condition monitoring nd fult dignoing re improved obviouly. opyright 4 IF Publihing. L. Keyword: ondition monitoring nd fult dignoi enor plcement Bode enitivity function.. Introduction lrge complex mechtronic ytem the vehicle control ytem of the wepon ytem i in chrge of the importnt opertion uch leveling erection nd o on. In opertion of the vehicle control ytem the control of the hydrulic ytem i relized through electromgnetic vlve controlled by computer nd the correponding function of mechnim ytem i implemented under the drive of hydrulic ytem. To mter the opertion tte of vehicle control ytem nd void ccident it necery to tudy the condition monitoring nd fult dignoing of vehicle control ytem. To monitor nd dignoe the ytem condition the firt conidered problem i the plce where the enor re locted. In vehicle control ytem there re lot of point poition which cn be ued to plce enor. It impoible to cquire ll dt which cn be cquired for the im of economizing cot nd enuring relibility. o the optiml plce which cn reflect the fult condition informtion mximlly mut be found to plce enor mong ll the cquired plce nd obtin the rich informtion of the ytem t lowet cot. ompring with rpid development of condition monitoring nd fult dignoi the optiml enor plcement problem h not provoked the ttention t ll time []. The beginning reerch of the optiml enor plcement w executed in 97 [-4] in 997 Lmbert hd nlyzed enor plcement uing fult tree nd bed on the influence of fult reource to procedurl vrible. But thi method hd no cpbility to del with loop nd the ging w very trong beide developing fult tree will led to error by itelf. In 979 Iri put forwrd the culity nlyi ide for ytem fult bed on Directed rph nd tudied the optiml enor plcement problem. fter tht mny cholr tudied Directed rph profoundly nd contructed fult dignoi 5

2 ytem bed on rule [5-7]. Directed rph model provide figure expreion method iming t monitoring proce which h the dvntge tht it ey to be built nd cn ue veted lgorithm of grph theory. But the retriction fctor of thi method re very trictly nd not ey to meet. In 3 to liner tructured ytem which contin diturb ignl to meet the olved condition of fult detection identify ommult hd completed the reerch work through dding enor t the lowet cot [8]. But it olution procedure which h exceive ubjective component w too complicted. ompring with thi method the optiml enor plcement theory bed on Bode enitivity function which w provoked by Yonghui Xu provide n importnt reference nd guidnce epecilly for the complicted ytem [9] uch vehicle control ytem which h mny mll ubytem. prmeter vector to the ytem i very lrge contrry i the me. o the mgnitude of mplitude of the Bode enitivity function cn be ued to intruct the enor plcement... Optiml enor Plcement Method Bed on Bode enitivity Function Fig. how typicl cloed loop ytem. c ( ) ( ) z ( ) nd b ( ) re defined the trnfer function of control unit driver unit performnce unit nd feedbck unit eprtely. B re the monitoring point which tnd of ytem output feedbck output nd control unit output eprtely.. Optiml enor Plcement Theory Bed on Bode enitivity Function [] I () + c () () () Y () B b () z.. Bode enitivity Function Fig.. typicl cloed loop ytem. Reviewing the liner time invrint ytem hown in Fig. it ingle input nd ingle output ytem. The trnfer function of the ytem minly depend on nd prmeter vector where [ ] r. T i () t y() t ( ) Fig.. typicl liner time invrint ytem. uppoed ( ) ( ) where nd re the rel trnfer function nd nominl trnfer function eprtely the Bode enitivity function cn be defined : i ( ) In generl ( ) ln ln i i i () i the complex frequency j function of ( σ + jw). When jw ( jw ) i the frequency repone of the function. j To pply conveniently the mplitude or modulu of jw i dopted reference vlue. If the j ( ) mplitude or modulu i too big in pecil frequencydomin tht i to y the influence generted by ocite with eqution () the number of Bode enitivity function i 9 on the three given point which cn be expreed mtrix form (eqution ()). The row of the mtrix tnd for the poible plce of enor nd the rry tnd for the influence to unit output by the fult. To expre imply the poition of detection point nd the nme of fult unit re ued to denote the upercript nd ubcript of the enitivity function. Y B b b b Y B () Y B z z z The olved reult cn be expreed : The monitoring point plce i the more portble plce to mount enor where the clcultion reult i. Hence from the bove enitivity vector we cn infer the concluion: ) If the enor i mounted on point the gined informtion i the mot which include the condition informtion of driver unit performnce unit nd feedbck unit. ) If the enor i mounted on point the mll quntitie informtion cn be chieved. 5

3 3) If the enor i mounted on point B it difficult to chieve ny informtion bout ytem condition. Extending the bove concluion to the typicl cloed loop neted ytem hown in Fig. 3 if the repone of outermot lyer ( ) contin integrtion component the numericl tbulr of enitivity function illutrted in Tble cn be chieved. The enitivity function vlue in the tble cn be ued to guide the plcement of enor. R() Y + () N () N... () () () + () c B c B... ( ) () + cn B N N () N Fig. 3. Typicl cloed loop neted ytem. pn Loop N... Loop Loop Tble. Numericl tbulr of enitivity function for typicl cloed loop neted ytem. N B B N N N pn... N N From Tble we cn chieve the following concluion which cn be ued to guide the enor optiml plcement of vehicle control ytem: ) The output of the ytem nd enor how no enitivity to the fult of performnce unit. ) The output of the ytem how enitivity only to the enor fult of the outermot lyer. 3) Except for the output of outermot lyer enor the output of the enor how enitivity to the fult which ppered in the outermot lyer enor nd itelf loop enor. 3. imultion Experiment nlyi The vlidity of optiml enor plcement method bed on Bode enitivity function i certified through two circuit cloed loop ytem imultion model. The contructed cloed loop i hown in Fig. 4. In the ce of gurnteeing the vlidity of imultion experiment to reduce clcultion the trnfer function in Fig. 4 re et : N I() + - Input dd B ( ) ( ) 3 (3) c c z ( ) ( ) ( ) ( ) b (4) (5) c + c - dd B Fig. 4. imulink imultion model of two circuit cloed loop ytem. To two circuit cloed loop ytem the monitoring point re plced on the given point B B nd. ccording to the clcultion method the enitivity function expreion of fult unit in the monitoring point cn be expreed : b z Y() B -c c z (6) + czb + c cz B b b b -cz (7) b + czb + c cz B B B z z (8) + + c z b c c z + (9) + + B c z b czb c cz + () + + B c c z b czb c cz b c c z b c z b c c z c c z b ( ) () 5

4 z c c z b b c z c z b c c z b c b b ( ) z () czb c cz (3) + czb + c cz ubtituting eqution (3) (4) nd (5) into eqution (6)~(3) the explicit expreion of the correponding enitivity function cn be chieved nd the mplitude frequency curve i hown in Fig. 5. From Fig. 5 in low frequency the mplitude of enitivity function indicte tht the fult condition detection of feedbck unit b cn be fulfilled through plcing monitoring point in B nd the fult condition detection of feedbck unit cn be fulfilled through plcing monitoring point in B nd to the fult detection of drive unit nd performnce unit the enor mut be plced in point. enitivity.5 () (b) (d) (e) (f) (g) (h) Frequency(rd/) Fig. 5. mplitude frequency curve of Bode enitivity function. To further certify the correponding reltionhip between the enor plcement concluion bed on Bode enitivity function nd the reltive trength of reidul ignl of the detecting point in fult condition preintll fult model i dopted to crry out certified experiment. Bed on the imultion model the preintll fult i et the gin vlue of (c) feedbck unit drive unit nd performnce unit re decreed percent in the time of econd the reidul ignl of the detecting point in imultion experiment re illutrted in Fig. 6 () Fig. 6 (b) nd Fig. 6 (c). The concluion of enitivity function re proved by the reidul ignl curve of the monitored point. If the performnce unit or drive unit pper fult the reidul output ignl of control unit re not equl to zero o the monitoring point cn be plced on the terminl of control unit. If the feedbck unit hppen to occur fult the reidul output ignl of ytem output feedbck unit nd control unit re ll not equl to zero thu ll thee output cn be ued to et monitoring point. When the feedbck unit h fult it reidul output ignl i tble nonzero vlue the detecting point cn be plced in the feedbck output poition. ompring Fig. 5 with Fig. 6 we cn infer tht t low frequency domin the correponding fult unit whoe mplitude of enitivity function i bigger will hve bigger reidul vlue in monitoring point. Thu the option of monitoring point through mplitude of enitivity function i reonble. t circumtnce of the three fult condition the reidul vlue in ytem output i zero pproximtely. o in the cloed loop ytem the trditionl ytem performnce judging method from the ytem output h mny flw nd cnnot find the incipient fult in the inner ytem timely. Reidul Reidul Reidul. -. B -.4 B Time() 3 () the reidul ignl of excittion unit or execution unit filure B B Time() 3 (b) the reidul ignl of the detection on the feedbck unit fult B B Time() (c)the reidul ignl of excittion unit or execution unit filure Fig. 6. Reltionhip curve mong fult unit reidul ignl nd monitoring point. 53

5 4. Bic cheme of Optiml Vehicle ontrol ytem enor Plcement ccording to difference of tructure nd function the vehicle control ytem cn be prted into three min component hydrulic ytem electric ytem nd mechnim ytem. The monitoring nd dignoi of mechnim ytem doe not need to mjor conider for it high relibility. o the problem of optiml enor plcement minly im t hydrulic nd electric ytem. 4.. enor Plcement of Hydrulic ytem complex ytem ccording to the different opertion procedure hydrulic ytem i contructed by mny ubytem nd the fulfillment of the function re ll relized by thee ubytem. o when plcing enor every ubytem hould be conidered. If the ubytem i cloed loop ytem which contin integrting element the optiml enor plce cn be found through pplying the bove reult imply generlly peking the optiml poition i directionl control vlve. If the ubytem doe not contin integrting element the front-end or rer-end of the high fult rte element uch pump hydrulic cylinder re often choen the etting point of enor. To oil ytem for the elf-complex vibrting enor nd temperture enor ll dded to chieve good monitoring effect. 4.. enor Plcement of Electricl ytem For the retriction of pce dimenion wepon ytem often pplie modulrized deign o it difficult to meure the inner of element or circuit. The poition which cn be meured only include the I/O port of control ytem nd individul element. In trditionl the enor re often plced in the I/O port of electric equipment ccording to the importnce nd mlfunction probbility. But if the monitored unit i cloed loop ytem which h integrting element it difficult to mke correct judgment of opertion tte of electricl ytem only through meuring the I/O of the ytem. The min reon lie in to cloed loop ytem even if the prmeter of the inner circuit element h been chnged the meured ignl in the output poition of ytem my jut devite the norml rnge intntly it will retore rpidly for the regulting ction of feedbck. o in thi circumtnce the fult ignl i trnient ignl which cn not be chieved eily. ccording to the enor plcement theory bed on enitivity function only the ignl which i extrcted from the front-end of trouble unit i continuou nd tble fult ignl which devite from the norml domin. ccordingly new cheme of enor plcement i dopted which plce the enor in the front-end of performnce unit poibly Mtter Need ttention To the whole vehicle control ytem hydrulic ytem electric control ytem nd mechnim ytem compoe united whole body where hydrulic ytem i equivlent to performnce unit electric control ytem i looked on controller nd mechnim ytem i thought to be performnce unit. In opertion the three component dded enor contruct cloed loop control ytem. Therefore the correponding enor re plced in the output terminl of electric ytem i the optiml cheme. On the other hnd for the cro nd mergence of ubytem the vehicle ytem i mde quite complex. One component of the ytem which i recognized cloed loop ytem t firt will be chnged into performnce unit or controller t n open loop ytem with the enlrgement of obervtion domin. Thu when optimizing the plcement of enor the rule tht plcing enor from the big ytem to mll ytem hould be obeyed. The poition of enor in big ytem hould be conidered firtly ccording to it tructure then the econd tep i to conider the plcement of enor in mll ytem. t the me time the relibility ignificnce nd other fctor hould lo be conidered. Of coure beide thinking bout the effect of fult monitoring nd dignoi the ddition of enor lo conider the reliztion cot proceing cpbility nd improving complexity nd decreing relibility which re generted by dding enor. The option of the optiml cheme i ynthei of mny influencing fctor which hould be conidered eriouly in relizing nd the cheme lo hould be checked by experiment nd prctice. 5. oncluion The enor plcement bed on Bode enitivity function i mthemtic model-bed method in eence which i quite fit to the ytem which operted long preintll trck uch the vehicle control ytem of the wepon ytem. The conidertion trting point of enor plcement of detected unit i not the ppering of functionl fult in trditionl ene but the performnce prmeter chngeble. In other word the ytem my operte t norml ttion even if the fult phenomenon bed on Bode enitivity function hppened epecilly for thoe ytem which hve feedbck modultion cpbility. In ce of thi circumtnce the provided enor plcement method bed on Bode enitivity function cn find the incipient fult of the ytem oon poible nd the method lo h the forect cpbility which i quite importnt to wepon ytem. Reference [].. Khn D. eglrek J. Ni enor loction optimiztion for fult dignoi in multi-fixture 54

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