Sesors & Trasducers, Vol. 66, Issue 3, March 04, pp. 9-95 Sesors & Trasducers 04 by IFSA Publshg, S. L. http://www.sesorsportal.com Desg ad Research o Automotve Cotroller Area Network Bus Aalyzer Hogwe CUI Shezhe Polytechc, Shezhe, 58055, Cha Tel.: 86-0755-67309, fax: 86-0755-673033 E-mal: hogwecu@szpt.edu.c Receved: Jauary 04 /Accepted: 8 February 04 /Publshed: 3 March 04 Abstract: The detecto method of automotve cotroller area etwork bus s researched ths paper. Falure detfyg of CAN bus uder dfferet workg codtos has bee realzed. I order to realzg tellget falure dagoss, data fuso meas has bee put forward ths paper. The composto of aalyss ad detecto system s troduced. By aalyzg ad processg the data of CAN bus ad sesors, work codto of automotve s acheved. Mult-patter data fuso model ad algorthm for falure dagoss are researched. The aalyzer ad detecto system desged ths paper ca be appled to automotve fault aalyss, troubleshootg ad mateace. Copyrght 04 IFSA Publshg, S. L. Keywords: Cotroller area etwork, Bus, Automotve, Detecto, Data fuso.. Itroducto May mcrocotrollers have bee used automotve. The commucato of formato s ubqutous automotve ege, chasss ad electrcal system. The status formato of each system ca be shared. Wth a automotve commucato system the formato trasfer s frequetly acheved by cotroller area etwork whch acts as a carrer for the formato sgal. So a hghly advaced ECU (electroc cotrol ut) of ege, chasss ad vehcle body should have the fucto of data acqusto, data maagemet, trasmsso ad formato sharg. Cotroller Area Network techology has bee quckly adopted by automotve dustry 993, t became the teratoal stadard kow as ISO 898. CAN bus s a asychroous seral bus etwork that coects devces, sesors ad actuators for cotrol applcatos. Frst proposed by Bosch Compay, CAN bus s part of a computer etwork system ad s wdely used automotve. Automotve cotrol uts ca be coected to form a vehcle etwork system by usg CAN data bus. The exchage ad sharg of data ca be acheved betwee each cotrol ut the automotve. The applcato of CAN data bus techology greatly reduces the umber of sesors ad wres. Safety, comfort, emsso ad ecoomc performace have bee greatly mproved by usg CAN bus. I order to mprove the relablty of CAN, the detecto method of automotve cotroller area etwork bus s studed ths paper. Ths paper presets the mportace ad ecessty for CAN detectg. Relablty ad faults dagoss of hardware are descrbed detal. Ths paper classfes the software ad hardware relablty ratoally o the bass of collectg ad aalyzg bus formato. Systematc methods of data acqusto, aalyss ad detecto are preseted [-3]. Artcle umber P_909 9
Sesors & Trasducers, Vol. 66, Issue 3, March 04, pp. 9-95. Detecto Method of Automotve Cotroller Area Network Bus By testg voltage, curret, waveform ad pulse sgal of sesors placed auto parts, the status of the car wll be judged. Ths s a tradtoal vehcle fault detecto ad dagoss method. Wth the developmet of data bus techology, may cars provde the CAN bus commucato terface stead of the sesor terface. Oce the ege malfucto occurs, because of the lack of CAN bus test equpmet, sesor sgal caot be measured drectly. So the workg codto of the ECU caot be detected. The work of mateace staff wll be lmted. Whe vehcles equpped wth CAN bus trasmsso system have a falure, mateace staff should frst detect whether the data trasmsso system s workg properly. If the multplex system has breakdow, the some formato etre automoble data trasmsso system are uable to trasmt. Therefore, electroc cotrol modules caot receve data formato ad are uable to work good codto. Geeral troubleshootg techques of automotve are depth aalyss accordg to the multplex system's cocrete structure ad cotrol loop. Therefore, the developmet of test strumets based o CAN bus should satsfy the broad market demad of auto mateace. Ths kd of strumet ca be used real-tme aalyss of ECU ut operato. It wll works uder varous actual codtos durg operato parameters testg. It should have strog resstace to Electromagetc terferece, ad be sutable for the requremets of the car EMC. Tradtoal automoble decoder collects data stream from OBD II stadard terface. Because CAN data trasmsso system's formato ad breakdow code are qute smple, complex malfucto s uable to be dagosed relably based o Fault code. Based o the data stream capture from CAN bus, the system developed by ths paper has acheved breakthrough ad developmet some aspects. Tradtoal fault detecto ad dagoss methods eed to collect the data flow through a commo terface ad sesor sgal. The system ca detect the vehcle CAN bus data, the operato of ECU, the sesor sgal falure ad other formato drectly [4-7]. The legth of CAN bus stadard data frame chages from 44 to 08 bt. Exteded data frame legth chages from 64 to 8 bt. CAN bus message s maly composed of a start frame, arbtrato feld, data feld, CRC checkg feld, respose feld ad the ed of the frame. The stadard frame form s show Fg.. CAN bus ca use may kds of physcal meda, for example twsted par le, optcal fber ad so o. The twsted par le s most commoly used o automobles. The sgal s set by dfferece voltage. Twsted par wres were called CAN_H ad CAN_L. Through collectg CAN_H ad CAN_L voltage sgal by detecto system, CAN bus data ad basc data lk work codtos ca by acqured. The schematc dagram of CAN bus aalyzer ad dagoss system s show Fg.. Fg.. The stadard frame form of CAN bus. Fg.. The schematc dagram of CAN bus aalyzer. The speed ad complexty of formato trasmsso may ot be the same for dfferet automotve cotrol system. Automotve ege, automatc trasmsso, suspeso ad ABS system eed to collect sesor's formato wth hgh speed ad acheve rapd cotrol of fuel jecto, gto ad brake actuators. The respose speed of the strumet ad formato dsplay system s relatvely medum. Addtoally, the cotrol speed of seat, door ad wdow s lower. From the perspectve of the reasoable desg, accordg to the dfferet requremets of formato trasmsso speed ad propertes, CAN bus system ca be dvded to dfferet levels of subsystems such as hgh, medum ad low speed. Gateway techology of CAN bus allows data that was prevously trasmtted the crcut doma to be trasmtted the packet doma. The key techology of CAN bus detecto s aalyzed elaborately. I dgtal sgal techology, a sgal that uses a postve (or egatve) excurso ad groud as the two bary sgal states. There s a rage of voltages that the crcut wll recogze as a hgh or low level wth CAN bus. CAN trasmts sgals o the CAN bus whch cossts of two wres. These two wres are operatg dfferetal mode. They are carryg verted voltages to decrease ose terferece. Usg two sgal trasmsso les, voltage outputs of CAN bus are forms of dfferece whch are called V-hgh ad V-low. Ordarly, the voltage of two les s same. The voltage s approxmately equal to.5 Volts. Dfferetal voltage of two wres whch 9
Sesors & Trasducers, Vol. 66, Issue 3, March 04, pp. 9-95 s called V-dff approxmates to zero. Durg the process of sgal trasmsso, the hgh level of V-hgh s 3.5 volts ad the low level of V-low s.5 volts. I ths case the dfferece voltage kow as V-dff s equal to volts. As a result, there are two kds of logc state o the CAN bus. Oe s recessve state whch s same as the voltage level of two wres. The other s domat state whch s dfferetal level of two wres. CAN bus s respectvely represeted by the domat kd ad recessve kd of logc value. The commucato s hadled accordg to rules gve by maufacturers. The voltage of CAN bus s show Fg. 3. Typcal domat ad recessve logc voltage values of CAN bus sgal are show Table. ad ECU cotrol parameters ca be dsplayed as dgtal ad graphcs o computer. The examato ad aalyss results s set to the o board mcrocotroller through commucato module. The purpose of fault dagoss ad real-tme motorg s realzed. Hardware block dagram of detecto system s show Fg. 5. Fg. 4. Data trasmsso of CAN bus. Fg. 3. The voltage of CAN bus. Table. Domat ad recessve logc voltage value. Voltage of CAN Bus V-hgh V-low V-dff Recessve.5 V.5 V 0 V Doma 3.5 V.5 V V 3. The Desg of Automotve Ca Bus Detecto System Whe the automoble has a breakdow, related sgals eed to be tested by cotroller area etwork detecto system. Troubleshootg s based o the results of testg aalyss. I addto, massve expermets eed to be carred o whe calbratg parameters of automotve electroc cotrol ut. I expermetal process, the teral sgal ad rug parameters of cotroller should be acqured tme. Ths formato s take to carry o the optmzato of the cotrol system as the bass. Ths eeds to develop a set of CAN bus motorg ad debuggg software that ca test varous kd of parameters real-tme ad debug ole cotrol parameters ad varables. Data trasmsso of CAN bus s show as Fg. 4. The CAN bus test module s added o the orgal electrcally cotrol system. Data commucato betwee the PC ad the vehcle cotrol system s acheved by hardware ad software. The operator may carry o the motorg to the cotrol system through computer. The ege workg parameters Fg. 5. Hardware block dagram of detecto system. By collectg data stream of CAN bus, dyamc operato parameters of automotve wll be acqured. All collected data s trasmtted to computer, so workg status of automotve ca be tested ad the fault ca be dagosed. Ths system wll carry o examato to the electroc cotrol module, qury whether the output sgal, workload ad other stuatos are ormal. Defect dagostcs ad aalytcs for commucato betwee dfferet cotrol uts has bee realzed by CAN bus test module. 4. Data Fuso Model ad Algorthm I order to meet the eed of the fault dagoss, the tegrato of processg the large umber of complex data should be cosdered. Complex data eed to be coverted to dstgush formato effectvely. The core of the system s the desg of correspodg data extract algorthm, data fuso model, ad formato forecast. As a result, the research of mult-patter data fuso model ad algorthm for falure dagoss s very mportat. 93
Sesors & Trasducers, Vol. 66, Issue 3, March 04, pp. 9-95 The data fuso s maly used processg of mult-sesor data. I the ordary crcumstaces, t carres o uder dfferet rules. Properly data acqusto s produced through mult-sesor collecto, classfcato ad tegrato. The basc objectve s to derve more formato from data combato. I order to mprove the syergstc effect, jot operato advatages of multple sesors should be made use of. Therefore, the overall effectveess of the sesor system s mproved [8-]. Adaptve weghted algorthm s adopted by detecto system to fuse the vehcle's feature formato, sesor formato ad CAN bus data formato. A varety of sesors are stalled o vehcle. Because the precso of sesors s varous ad exteral detecto codto s qute complex, there are large homogeety for the object to be measured. Therefore, ths paper adopts the adaptve weghted data fuso algorthm based o measured data. Correspodg weghts of dfferet data are determed by the measuremet accuracy. Weghts dcate the relatve mportace of measuremet data. Because the error of hgh precso sesor s small, correspodg weght s large. The measured data were multpled by weght umber. The dfferet sesor has the correspodg weght umber. I order to get the smallest total mea error, the measured value of each sesor eeds the correspodg weght factor usg adaptve method. Test system's data fuso value s show as Eq.. where s the fuso value, Xˆ = W X = W =, () =, () W s the weght factors of varous sesors, ˆX X s the observed values of varous sesors. Total stadard devato s show as Eq. 3. W = σ = σ, (3) Weght factors of varous sesors are show as Eq. 4. ' W = σ =, σ (4) Total stadard devato σ s the mmum value. Therefore, after extractg the best weght factor, the estmated value of data fuso ˆX ca be calculated. By comparg ad aalyzg expermetal results, the test system s able to accurately obta the fault formato of automotve cotroller area etwork. Accordg to the data flow of varous sesors, the system ca also aalyze the fault formato. Tps ad solutos are preseted. The system acheves the orgal desg requremets. The accuracy ad relablty s qute satsfactory. Expermetal result of automotve CAN bus waveform s show Fg. 6. Fg. 6. Automotve CAN bus waveform. 5. Coclusos By desgg hardware ad software system, real tme data acqusto, motorg recorder ad detfcato of automotve cotroller area etwork are acheved. The data of automotve CAN bus ad sesors are processed ad aalyzed. Dyamc operato parameters of automotve are acqured by the aalyzer ad detecto system through collectg data stream of CAN bus. Although the error detecto, sgalg ad fault cofemet defed the CAN stadard makes the formato of CAN bus correct ad cosstet. Fault detecto ca be hadled automatcally by the CAN bus aalyzer. CAN bus aalyzer make sure that the system s more relable. The detecto system s of great value to removg cpet fault of rug vehcle, mprovg relablty, ratoal matag ad proper specto. Ackowledgemets Ths paper s supported by School of Trasportato & Automotve Egeerg, Shezhe Polytechc. Refereces []. M. Hafer, M. Schuler, O. Nelles, R. Iserma, Fast eural etworks for desel ege cotrol desg, Cotrol Egeerg Practce, No. 8, 000, pp. -. []. G. R. Yousef, A applcato of artfcal eural etworks power system load modelg, Proceedgs of the IEEE Power Egeerg Socety Geeral Meetg, Sa Fracsco, Calfora USA, Vol., -6 Jue 005, pp. 308-33. 94
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