a computer-controlled engine test cell for engineering experiment

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1622 PROCEEDINGS OF THE IEEE, VOL. 61 , NO. 11, NOVEMBER 1973

A Computer-Controlled Engine Test Cell forEngineeringExperiments

JAMES H. RILLINGS, WENDELLD. CREPS, AND LAKSHMI S. VORA

Abstract-A computer-controlled engine test cell was developedfor conducting complex transient experiments with automotive en-gines. The test celluses a minicomputer with 16OOGword 16-b corememory to perform data acquisition and closed-loop control of theengine and dynamometer. A tabladriven real-time control programis used to duplicate the effects of vehicle, transmission, and roadnengine operation. Reference data and acquired data are exchangedover a high-speed communications channel between the minicom-puterand acentralizeddataacquisitioncomputer (DAC) system.Datacanbeplottedagainst imeorcross-plottedagainstotherparameters on a graphic cathodbray-tube display peripheral to theminicomputer.The user can interactwith hesystem ochangeparameters during the running of an experiment.

INTRODUCTION

IJ? O R T H E PAST several years the automotive industryhas facedmore evere hallengesots ngineeringcapabilities han thas faced inall heyears of i tsexistence. With he ndustrysgreaterawareness of safet yandenviro nment al problems, heseburdensonengineeringwill continue to increase in the future.

Traditional methods of design using data obtai ned fromsteady-state esting s no onger sufficient o solve many oftodays problems. For example, exhaust emissions are highly

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RILLINGS et al .:COMPUTER-CONTROLLED ENGINE TEST CELL 1623generalized input buffer

1 channel (16 b) ;generalized o utpu t buffer1 channel (16 b).

The analog and digital 1/0 are connected to the patch panelshown on the left side of Fig. 3 . This patch panel connects tothe ransducers n he est cell and hesignal-conditioningelectronics n he control room. The patch panel distributesthe resources of theminicomputer o hesignal lines beingused for the current experiment .The graphic termina l can be used as a teletypewriter-likedevice for alphameric input and output, and it can e used inavectorgraphics mode or pres enti ngdata i n the orm ofanalog plots and labeled graphs. I t is interfaced to the mini-computer hrough a teletypewritercontrolleroperating at100 charac ters/s.Because of the large volumeof dat a tha t s taken during atypical engine experiment, a bulk storage device is required.For reasonsof economy it was decided tose a nearby existingDAC with four disk drives as a bulk storage satellite to theminicomputer. The DAC operates in a continuous real-timemultitask mode and can supply remote computational sup-port for the minicomputer when needed. An interrupt-drivenparallel communications channel was established between thetwo compute rs using a generalized input buffer and general-ized output buffer o n the minicomputer, isolating line-receiverdrivers and digital 1/0 o n theDAC. This permits he womachines to exchange data at speeds exceeding 10 000 16-bwords/s, giving the minicomputer rapid access to a large bulkstorage pool.

GRAPHICS

Fig. 2. Engine test cell and dynamometer control console.

motebuildup of experimentsand apid nstallation n hetest cell.Theexhaust-emissionsanalyzers,not visible inFig. 2 ,measure the Federa lly required constit uents of carbon mon-oxide, oxides of nitrogen, and unburned hydrocarbons, aswellas oxygen and carbon dioxide.The engine can be instrumented o log dat a from up o40 variables, among which are engine speed, engine orque,throttle ngle, park dvance,manifoldvacuum, xhausttemperature, and many other temperatures and pressures de-pending on the objectives of the particu lar experim ent beingconducted.Th e controlled ariablesnclude nginepeed, nginetorque,hrottlengle,parkdvance,nd thers when


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1624 PROCEEDINGS OF THE IEEE, N O V E M B E R 1973

Fig. 3. Control minicomputer, graphic terminal, and patch panel.


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RILLINGS et al . : COMPUTER-CONTROLLED ENGINE TEST CELL 1625

RUN THEPRDSPAHS LVEHICLE

YESr

SIMULATOR -+ R E F E E S C E I N T H ETORE THEDATA DATA INPROGRAM DACD R I V I N GTXROUGHCYCLE

WAD GRAPHICS pLaT THEMINI A R E T H E Y* NOATISFACTORY?TEST ~ S ~ T S-NTOKIN1 -I

C W G E C ONT RO LLaoP PARRMETERSUSRY; OPERATORCCWWRJICATIONSSYSTEM

1RE RDY TORUNEXPERIMENT ANDGATHER DATAFOR ANALYSIS

Fig. 5 . Functional block diagram of an experiment to tune a control algorithm.

system timingmeasured variables:calibration curvesmeasurement ratesfiltering

calculated variablesequationscontrolled variables:control ratescontrol algorithmslogged variables:

the card reader. The supervisory program reads nput vari-ables and controls output variables during real-time tests.ILLUSTRATIVEXAMPLETh e following example illustrat es theuse of this system totuneanalgorithm orenginecontrol.Open-loop eference

valuesfor he wocontrolledparameters,enginespeedandthrottle ngle, were obtained romanautomotive vehiclesimulationprogram [ 2 ] whichcalculatesengineparametervalues for a given in put of vehicle description and road-speedprofile. For his test the road-speed profile chosenwas the


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1626 PROCEEDINGS OF TEE IEEE, VOL. 61 , NO . 11, NOVEMBER 1973and allows heoperator o nterface with hisexperiment. heircontributions o heminicomputer-to-DACcommunica-Having a small powerful computer dedicated to single appli- tions programs.cation makes facilities like his practical. REFERENCES

ACKNOWLEDGMENT [l ] J . F. Cassidy and J. H. Rillings, Tra nsien t engine testi ng by com-putercontrol,presented at he SAE Nat.AutomobileMeeting,J. Farrell, A. A. K o k c ~ , . r ab ld , nd L. 121 W. C.Walters,Generalurposeutomotive vehicle performanceTroxel or heirhelp,andalso R. Chaneyan d G. Kimm or Engineers, an. 10-14, 1972, Paper 720043.and economy simulation, presented o he Society of Automotive

Theuth ors wish tohank J. Cassidy, V. Coppola, Detroit,Mich.,May22,1972.

The Use of Minicomputers n Racetrack Totalisator SystemsBURT H. LIEBOWITZ AND RICHARD S. WOLF

AbstracA racetrack totalisator is desuibed which is capableof processing 300bets/s from up to 1OOO ticket-issuing machines.The system contains which provide high-reliabilitylow-castomprttingpower, apableof DpPortfng the requirementsofany racetrack n theUnited States orThe coanprrters are duplexed.. Both eaanputersprocess every betand operator action Either computer can continue processing if theother fails. The softwan provides extensive error checking of allhardware compon- Al l bets are logged to magnetic tape, whichc a n b e ~ t o n s t .r t t h e ~ i a c u r eo f a s y s t e m b l o w . Thereal-thaeprogramwasrrittminmachinelanguageandaspeeiany developed higher levelLpngFegeThe master 6le contains

track may have from100 to 600 icket machines. There are 11dist inct typ es of bet ting pools used at AmTote tracks.2) Thesystemmust be accurateand eliable.AmToteguarantees hesystem o tscustomers; i.e., AmTote willmakegoodany inancial osseswhichcan be attrib uted oequipment failure. The system must not o down because lost

time means lost money to track management. Also, horse anddog bettors are not the most patient people in the world, andare apt to ive vent to their emotions in publicf they cannotplace their bets in a timely fashion.


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a computer-controlled engine test cell for engineering experiment

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