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Int J Adv Manuf Technol (2010) 51:233246DOI 10.1007/s00170-010-2626-2ORIGINAL ARTICLEDevelopment of an automated testing systemfor vehicle infotainment systemYingping Huang & Ross McMurran & Mark Amor-Segan & Gunwant Dhadyalla &R. Peter Jones & Peter Bennett & Alexandros Mouzakitis & Jan KielochReceived: 18 December 2009 / Accepted: 12 March 2010 / Published online: 15 April 2010# Springer-Verlag London Limited 2010Abstract A current premium vehicle is implemented witha variety of information, entertainment, and communicationfunctions, which are generally referred as an infotainmentsystem. During vehicle development, testing of the info-tainment system at an overall level is conventionally carriedout manually by an expert who can observe at a customerlevel. This approach has significant limitations with regardto test coverage and effectiveness due to the complexity ofthe system functions and humans capability. Hence, it ishighly demanded by car manufacturers for an automatedinfotainment testing system, which replicates a humanexpert encompassing relevant sensory modalities relatingto control (i.e., touch) and observation (i.e., sight andsound) of the system under test. This paper describes thedesign, development, and evaluation of such a system thatconsists of simulation of vehicle network, vision-basedinspection, automated navigation of features, randomcranking waveform generation, sound detection, and testautomation. The system developed is able to: stimulate avehicle system across a wide variety of initialisationconditions, exercise each function, check for systemresponses, and record failure situations for post-testinganalysis.Y. Huang (*) : R. McMurran : M. Amor-Segan : G. DhadyallaWarwick Manufacturing Group, University of Warwick,Coventry CV4 7AL, UKe-mail: yingping.huangwarwick.ac.ukR. P. JonesSchool of Engineering and IARC, University of Warwick,Coventry, UKP. Bennett : A. Mouzakitis : J. KielochJaguar Land Rover, Engineering Centre,Coventry, UKKeywords Automatic testing . Infotainment .Image processing . Modeling and simulation .Hardware-in-the-loop . Robustness . Validation1 IntroductionAn infotainment system provides a variety of information,entertainment, and communication functions to a vehiclesdriver and passengers. Typical functions are route guidance,audio entertainment such as radio and CD playback, videoentertainment such as TV and interface to mobile phones, aswell as the related interface functions for the users tocontrol the system. There has been a large growth in thisarea driven by rapid developments in consumer electronicsand the customer expectations to have these functions intheir vehicles. Examples of this are surround sound, DVDentertainment systems, iPod connectivity, digital radio andtelevision, and voice activation.With this growth in features there has been acorresponding increase in the technical complexity ofsystems. In a current premium vehicle, the infotainmentsystem is typically implemented as a distributed systemconsisting of a number of modules communicating via a highspeed fiber optic network such as Media Orientated SystemsTransport (MOST). In this implementation the infotainmentsystem is in fact a System of Systems (SOS) with individualsystems having autonomy to achieve their function, butsharing resources such as the HumanMachine Interface(HMI), speakers, and communication channel 1. Typicalissues with such SOS are emergent behavior as systemsinteract in an unanticipated manner particularly duringsome initialisation conditions where it may be possible toget delays and failures in individual systems. These maynot be readily observable until the particular part of the234system is exercised. During vehicle development, valida-tion of the infotainment system is extremely important andis conventionally carried out manually by engineers whocan observe at a customer level but this has limitations withregard to test coverage and effectiveness. The firstlimitation is the time available to do manual tests, whichis constrained by the development time scale and engineersworking hours. The second is in the repeatability of the test,which is subject to human error. Hence, there is arequirement for an automated infotainment test capability,which replicates a human expert encompassing relevantsensory modalities relating to control (i.e., touch and voice)and observation (i.e., sight and sound) of the system undertest. This test capability must be able to stimulate thesystem across a wide variety of initialisation conditionsincluding those seen under cranking, low battery or faultconditions, exercise each function, check for systemresponses, and record related data, e.g., MOST bus trace,in the case of a malfunction for subsequent analysis. Thispaper describes the design and development of such asystem as part of a UK academic and industrial collabora-tive project into the validation of complex systems.In the system, a Hardware-in-the-Loop (HIL) platformsupported by a model-based approach simulates the vehiclenetwork in real time and dynamically provides variousessential signals to the infotainment system under test. Sincethe responses of the system are majorly reflected in thedisplay of the touch screen, a machine vision system isemployed to monitor the screen for inspection of thecorrectness of the patterns, text, and warning lights/tell-tales.The majority of infotainment functions are accessed by theuser through an integrated touch screen. In order to achieve afully automated testing, a novel resistance simulationtechnique is designed to simulate the operation of the touchscreen. It is known that voltage transient processes, such asengine start where an instantaneous current inrush can reach800 A, may result in some failures on the system. To test thesystem robustness against low voltage transient conditions, atransient waveform generator is developed to mimic threespecific transient processes. A testing automation softwareintegrates and controls all devices to form a fully automatedtest process, which can be run continuously over days oreven weeks. The developed testing system not only makesvarious testing possible, repeatable, and robust, but alsogreatly improves testing efficiency and eases the task oftedious validation testing.Model-based testing of functionality of an ElectronicControl Unit (ECU) using HIL has been implemented byautomotive manufacturers over the last few years 25.Currently, Jaguar Land Rover (JLR) has adopted the HILtechnology for automated testing and validation of elec-tronic body systems, powertrain, and chassis controlsystems 6, 7. The benefits of this technology includeInt J Adv Manuf Technol (2010) 51:233246automated testing, earlier testing before physical prototypevehicle build, ability to perform robustness and dynamictesting, and reduction of supplier software iterations.Machine vision systems have been used in many manufac-turing applications such as automotive 810, roboticguidance 11, and tracing soldering defects 12, 13. Theauthor also employed machine vision technology forobstacle detection in advanced driver assistant systems14, 15. However, no research has been reported using amachine vision system for design validation testing.Validation testing in the design stage is very much differentfrom testing in manufacturing. Firstly, design validationtesting requires diverse test cases covering a large numberof, rather than a restricted, set to prove proper design. Theonly way to generate the test cases when the car is in theearly development phases is using model-based testingtechniques, which simulate vehicle-operating conditions inreal time. Secondly, design validation testing requiresiterative and repeated tests for robustness evaluation,although it does not require a high volume of parts to betested. Thirdly, design validation testing needs frequentadaptation of the testing system for different types of carsor for different development stages of the same car. Onenovelty of this paper is the integration of the machinevision and HIL techniques for complex design validationtesting. In addition, the paper proposes a novel pseudo-random concept for generating three voltage transientwaveforms, which allows the testing to mimic the randomprocess as seen in real cases, and also enables the testing tobe regenerated for further investigations. Furthermore, acommon approach to mimic the operation of the touchscreen by a human is by using robot arms. In this design, acrafty resistance simulation approach replaces the robotarms to achieve the goal. The approach can be completelyimplemented in software by using the HIL simulator,therefore eliminating the need of complicated mechanicaldevices such as robot arms, pneumatic/hydraulic, andsolenoid actuators.2 System configurationsThe configuration of the system developed for testing theinfotainment system is shown in Fig. 1. The system consistsof six vital elements including the unit under test, HILtester, machine vision (camera), operation of the touchscreen, transient waveform generator, and test automation.The infotainment system under test consists of a numberof modules including the radio/CD player, amplifier(AMP), navigation system, blue tooth/telephone/USB,vehicle setup, auxiliary audio interface, and climate controlfunctions. The HMI is based primarily on a 7 TFT resistivetouch screen with additional hard keys on an IntegratedInt J Adv Manuf Technol (2010) 51:233246Images (referenced to test)EthernetRS232 SerialCamera235Vision TestTriggerTestResultsControl ParametersHIL TesterResistive control of touch screenHostPCOpticalCANTouchScreenCapture DataTest AutomationscriptsTest ScriptPrecondition.test.post conditionPrecondition.test.post conditionTrigger LowVoltage testprofileRS232ICP &Remote ContClimate/Setup/InterfaceICMgatewayPrecondition.test.post conditionPrecondition.test.post conditionPrecondition.test.post.test.post condition.Precondition .test.post conditionPrecondition .test.post conditionPrecondition .test.post conditionPowerSupplyRadio/CDplayerMOSTRingOptolyseranalyzerPrecondition .test.post condition.Blue tooth/MOST AnalyzertriggerFig. 1 System configurationTransient waveformgeneratorAudio output monitoringNavigationAMPPhone/USBControl Panel (ICP) in the center console and remotecontrols on the steering wheel. Audio output is via a DSPamplifier. Communication between the modules is througha MOST optical bus carrying control, data, and audioinformation. The infotainment system is connected to therest of the vehicle via a module called ICM acting as agateway between MOST and a vehicle Controller AreaNetwork (CAN) bus. It is worth noting that the ICP and theremote controls on the steering wheel reside in the vehicleCAN bus. In addition, a MOST analyzer was connected inthe MOST ring during the testing. The MOST analyzer wascontrolled by the HIL tester via digital outputs to trigger thelogging of the MOST traces when a failure occurs.Within the testing system, the HIL tester simulates thevehicle network and dynamically provides various essentialsignals to the infotainment system under test. It also acts as acontrol center to control other devices. For example, it sendscommands via a serial port to trigger the camera and receivethe inspection results from the camera. The machine visionsystem (camera) checks the responses of the system bymonitoring the display of the touch screen such as patternsand text. The operation of the touch screen is achieved byusing a resistance simulation approach, which is imple-mented in the HIL tester. By using this approach, the testingsystem can get access to the majority of infotainmentfunctions. The transient waveform generator producesvoltage signals and powers up the infotainment system viaa programmable power supplier. The waveform generator,mimicking three voltage transient processes, is used fortesting system robustness against low voltage events. Thetest automation is running in the host computer to integrateand control all devices to form a fully automated testprocess. In addition, the host PC has been linked with themachine vision system via a TCP/IP Ethernet communica-tion. This link allows the storage of time-stamped images inthe host PC so that the behavior of the unit under test can bereviewed offline in terms of the test results. The followingsections describe the individual elements of the automatedtesting system including the HIL tester, vision-basedinspection, automated touch screen operation, transientwaveform generator, and test experiments.3 HIL testerA dSPACE simulator 16 was used to form a hardware-in-the-loop simulation test system. The HIL test systemsimulates the vehicle CAN bus to provide power modesignals to the MOST Network via the MOST gateway. Italso simulates the ICP to operate the infotainment system.Test ResultsconditionMOST236Int J Adv Manuf Technol (2010) 51:233246Fig. 2 dSPACE real-time simulatorSimulation ModelsExpansion boxSimulation of Power Mode andintegrated control panel - CANDigital signalprocessorPower supply controlSimulation of touch Screen operationand On/Off Switches -resistanceoutputsSound detection and measuringsound frequency A/D inputsSerial communications RS232Real-time simulatorStandard I/OInterfaceCANI/O RS232In addition, the HIL tester also provides RS 232 serialinterfaces to communicate with the camera and transientwaveform generator, resistance simulation to operate thetouch screen, and an A/D interface for detecting sound andmeasuring sound frequency.The dSPACE Simulator consists of simulation models andexpansion hardware as shown in Fig. 2. The expansion boxincludes one processor board DS1006 and one interfaceboard DS2211. The DSP board runs the simulation models,while the interface board provides various interface linkswith other devices, such as CAN, resistance outputs, A/Dconverters, analog/digital input and output, and RS 232serial communication to control the machine vision system.In the HIL system, simulation models are implementedin MATLAB/Simulink/Stateflows and compiled using theauto-C-code generation functions of Matlabs Real-TimeWorkshop for real-time execution.3.1 Simulation of power modeThe behavior of the components of the Infotainment systemis determined by a CAN signal known as Power mode,which indicates the operational state of the vehicle e.g.,ignition off, ignition on, engine cranking, enginerunning, etc. To test the performance of the infotainmentsystem under cranking conditions, the car under test must bein the engine-cranking state when applying crankingtransient voltages to the car. Moreover, any subsequentfunctional tests must be conducted in the engine-runningstate after the cranking. In a real car, power mode messagesare transmitted by the body ECU connected to the CAN.Since we were testing the infotainment system on a testplatform representing a real car sometimes, in order togenerate the correct power mode behavior, we utilized CANsimulation of the HIL tester to simulate the body ECU totransmit power mode messages to the MOST gateway.3.2 ICP simulationThe Integrated Control Panel of the infotainment systemprovides users with a number of hard keys for operating thesystem. The functions controlled by the ICP includeselection of the audio sources, loading and ejecting CDs,seeking up/down for radio stations and CD tracks, volumecontrols, and so on. To enable an automated testing of thesefunctions, the ICP must be controlled by the test center, thedSPACE real-time simulator.The ICP electronic control unit interfaces with a vehiclevia the vehicle CAN. Therefore, the ICP unit was simulatedby using the CAN simulation of the dSPACE simulator.The models of ICP simulation are shown in Fig. 3.3.3 Sound detectionSound detection contains two aspects i.e., detecting soundon or off and detecting the frequency (dominant) of thesound. The sound signal is sampled from the speaker end asshown in Fig. 1, and converted into digital signal by an A/Dconverter within the dSPACE simulator. The sound on/offis determined by checking the amplitude of the signal. Thefrequency of the sound is detected by the specific circuit ofthe simulator. The purpose of detecting sound frequency isto identify a sound source and active CD track. The modelis shown in Fig. 4.Int J Adv Manuf Technol (2010) 51:233246Fig. 3 Model of ICP simulation3.4 Simulation of serial communicationsThe RS232 serial communication is used to establishthe link between the HIL tester with the camera and thetransient waveform generator so that closed loop testingcan be performed. During the test, the HIL tester is thecontrol center to command the camera and the transientwaveform generator and to obtain the inspection resultsfrom them. For example, the camera needs to becommanded to select a specific image processing jobfile for specific testing. The checking results generatedby the camera need to be returned to the HIL tester.The transient waveform generator needs to be com-237manded to generate a specific cranking waveform forspecific testing. The parameters of the waveformresulting in a failure need to be returned to the HILtester so that this specific testing can be duplicated inthe later analysis stages.A simplified version of the simulation models of theRS232 serial communication is shown in Fig. 5. Atransmitted message is ended with a carriage return andhas a maximum length of 10 bytes. A received message hasa fixed length of 8 bytes. The first 3 bytes gives the resultname while the following 5 bytes indicates the resultvalues. For example, the active track number is abbreviatedas the result name ATN.238Fig. 4 Model of sound detection4 Vision-based inspection4.1 Machine vision systemThe machine vision system consists of a camera, lighting,optics, and image processing software. A Cognex In-sightcolor vision sensor 17 was selected for image acquisitionand processing, which offers a resolution of 640480 pixelsand a 32-MB flash memory. The acquisition rate of thevision sensor is 60 full frames per second. The imageacquisition is through progressive scanning. The imageprocessing software (In-sight Explorer Ver 4.2.0) provides awide library of vision tools for feature identification,verification, measurement, and testing applications. ThePatMaxTM technology for part fixturing and advancedOptical Character Recognition (OCR) tools for readingtexts 17 are available within the software. The primarysource of illumination is from a LED ring light withdirectional front lighting, which provides high contrastbetween the object and background. The selection ofoptical lens depends on the field of view and the workingdistance. In this setting, a lens with a focal length of 8 mmis used. Image processing task can be assigned intodifferent job files stored in the camera flash memory. Inthis work, the image processing jobs were organizedaccording to the system functions with five job filescorresponding to five display pages. Each job file conductsall visual inspections for the page required by the testspecifications. The visual inspections conducted in thiswork can be divided into three categories as follows.Int J Adv Manuf Technol (2010) 51:2332464.2 Inspection of patternsThe majority of infotainment functions are displayed tousers through the touch screen. Therefore, the majority ofthe functional testing is to check if the screen gives correctdisplay as expected. For example, we need to check thepage, temperature format, clock format, radio/CD sources,and so on. This checking can be done by inspectingpatterns in the specific screen areas. Fig. 6 gives anexample of checking the home page display. Initially, theleft upper corner pattern of the home page was trainedusing PatMaxTM tools and stored as a master pattern.During the test, the image captured from the unit under testwas compared with the trained patterns. The page wasrecognized based on the pattern matching score returnedfrom the PatMaxTM tools. As shown in Fig. 6, the homepage got the highest matching score of 99.9, while otherpages “Audio,” “Climate,” and “Comms” got lowermatching scores. The author has also applied the Pat-MaxTM tools for inspection of vehicle instrument cluster.More detailed information about how PatMaxTM toolswork is described in 7.4.3 Text recognitionThe CD track number and some warning messages need tobe checked for their correctness. This test aims atrecognizing and reporting these texts.In the image processing library, the OCR tools aredesigned to recognize a text string. However, this tool canInt J Adv Manuf Technol (2010) 51:233246a) Transmission modelb) Receiver modelFig. 5 Simulation models of the RS232 serial communication. a Transmission model, b Receiver model239240Fig. 6 Pattern inspectionInt J Adv Manuf Technol (2010) 51:233246TrainedPatternPattern matchingscore = 99.9Pattern matchingscore = 70Pattern matchingscore = 50Pattern matchingscore = 30only be used for identifying a text string with a knownnumber of characters. In our case, texts appearing on thescreen are distinct with different numbers of characters. Inorder to solve this problem, instead of identifying a wholetext string, each character of the string was recognizedseparately by treating it as a “blob”. An example is shown inFig. 7 for identifying a CD track number. We firstly used ablob tool to extract the blobs within the string and sort themin terms of their positions. Since characters were separatedfrom (not linked) each other, each character was recognizedas an individual blob. Sequentially, each blob area waslocated with a red text tool, and the character within theblob was recognized by comparing it with the trained fonts.All digits from 1 to 9 were pre-trained and stored using thesummation of the average values of the three colorcomponents within the region represents a specific color.By this method, we can identify a color within a button areaas shown in Fig. 8. Its worth pointing out that the colordetection based on the average value of RGB colors issimple but may cause some false detection in some cases.Examples are that the RGB values (255, 0, 0), (0, 255, 0),(0, 0, 255) and (85, 85, 85) indicate different colors buthave the same average value. However, the methoddeveloped works fine in the application since the colordetection is majorly for discriminating an active button,active CD, and active radio with a change from dark blue tolight blue. For identifying more colors, we may use a hue,saturation, and intensity (HIS) color model.“TrainFont” vision tool. Finally, all identified characterswere concatenated together to retrieve the entire string.5 Automated touch screen operation4.4 Color identificationAs the main HMI of the infotainment system, the touchSince the active button on the display is shown with adifferent color, color identification was used to check activebutton, active CD, active radio stations, and so on. The“ExtractColorHistogram” vision tool was used for thispurpose, which accesses every whole pixel in an imageregion to accumulate a color histogram. Each color pixel iscomposed of three separate color components: red, green,and blue (RGB). Each color component is converted to avalue from 0 to 255; therefore, the accumulated histogramscreen allows the user to navigate through various menusand screens to select and control a desired function, or toconfigure user preferences and defaults. Fig. 1 also shows asmall picture of the premium vehicle touch screen. In orderto achieve the goal of a fully automated infotainment testcapability which can replicate a human expert, an essentialrequirement is the ability to replicate the users touch screenbutton presses. Approaches for simulating user buttonpresses were investigated including the use of a roboticcontains 256 elements for each color component. TheColour value:31+112+171=314Colour value:69+232+241=542Extract andsort blobsFig. 7 Text recognitionRecognise characterwithin each blob areaFig. 8 Color identificationInt J Adv Manuf Technol (2010) 51:233246xYFig. 9 Four-wire resistive touch screenarm or finger, and an array of solenoid operated actuators.These approaches were discounted due to issues of eithercost, interference with the operation of the machine visionsystem, or limited upgradeability. As an alternative andmore suitable solution, a novel resistance simulationtechnique was developed for the purpose.5.1 Touch screen operationThe touch screen consists of two layers including a rigid glassback layer and a flexible polyester front layer, each with auniform resistive coating, separated by small insulatingspacers or dots. One layer is used to capture horizontal241equivalent to separated resistances are an analog represen-tation of the XY coordinates of the touch point. The touchscreen controller then converts these measured voltages intothe appropriate screen press coordinates.5.3 Resistive simulationResistance simulation was adapted to mimic a physicalpress of the touch screen like a human user operation. Fivesoftware controllable resistances in the HIL tester wereused to simulate the circuit shown in Fig. 11. Four of themsimulate resistances RX1, RX2, RY1, and RY2 while the fifthresistance mimics a short electrical contact as generated byphysical press. The simulation outputs were then connectedin parallel with the real touch screen.Calibration must be performed to build up a look-uptable listing the coordinates on the touch screen and itsequivalent resistances. Accordingly, any point in the touchscreen can be virtually pressed by assigning the equivalentresistance values to the resistances. In practice, the touchscreen was divided into many small areas, eachcorresponding to a set of resistance value.5.4 Benefits of the methodThe approach of mimicking screen button press offers thefollowing benefits:coordinates, and the other layer vertical coordinates. Electro-des at either side of each resistive layer are connected to thetouch screen controller. This arrangement is illustrated inFig. 9. When the screen is touched, the front layer is forcedagainst the back layer at the touch point and an electricalcontact is made between the two resistive coating layers.5.2 Measuring touch-point coordinatesThe equivalent circuit for such a four-wire resistive touchscreen is illustrated in Fig. 10.The values of resistances RX1, RX2, RY1, and RY2 will varyaccording to the position of the touch point. The switch andthe resistor R represent the touch point and contact resistance.This means coordinates of a touch point are equivalent to a setof values of resistance, RX1, RX2, RY1, and RY2.It takes two steps to obtain respectively the X and Ycoordinates of the touch point. Firstly, to obtain the Xcoordinates, the touch screen controller applies a fixedvoltage across the back layer, and then uses the front layeras a voltage probe to measure the voltage at the touch point.It then repeats this process to obtain the Y coordinates byapplying a fixed voltage across the front layer, and using theback layer as a probe. This process is illustrated in Fig. 11.The resistive coating on each layer creates a potential&The approach does not affect the normal operation ofthe touch screen itself since the simulated equivalentcircuit is connected in parallel. The real touch screencan be operated alongside the simulated touch screen.This is particularly useful for experimental setup andmanual operation of the Infotainment functions.The approach does not obstruct the view of the display.This allows the machine vision system to operate easilyand without hindrance.This technique can easily and quickly accommodatechanges in screen layout resulting from either softwarechanges or changes in display/vehicle. New or changedbutton coordinates can be introduced by adding orupdating the corresponding resistance value mappings.divider at the touch point. The voltages Vx and VyFig. 10 Touch screen equivalent circuit242Fig. 11 Measuring touch-pointcoordinates6 Transient waveform generator6.1 Three voltage transient conditionsA transient waveform generator was developed tosimulate three voltage transient conditions includingEngine Crank, Contact Bounce, and Voltage Ramp(down/up), which have been specified in the JLREngineering StandardImmunity to Low Voltage Tran-sients 18. Engine Crank is the case when the car engineis cranking. A parameterized representation of thevoltage seen at the battery terminals is shown inFig. 12. The values of all parameters T1, T2, T3, T4,V1, V2, and V3 may randomly vary depending on factorssuch as system configuration, electrical load (imped-ance), battery state of charge, and ambient temperature.Contact Bounce reflects the voltage transient caused bypoor connections at the battery terminals. A poor connectioncan be generated by installation errors or damages to thewiring or connectors. Fig. 13 illustrates the parameterizedrepresentation of the contact bounce voltage waveform.Voltage Ramp is the voltage variation caused by a slowbattery discharge, dwell at low voltage and subsequenttrickle charge. A common example of these cases is: theengine is switched off but some vehicle loads are left onsuch as the lights or the radio. A parameterized represen-tation of the ramp profile is shown in Fig. 14.As shown in the figures, each type of waveform can berepresented by a set of parameters. In real situations, eachparameter can randomly vary. The variation of theparameters creates various combinations representing dif-ferent voltage scenarios. That is, these voltage scenarios canbe mimicked by manipulating these parameters.6.2 Pseudo-random distributionTwo types of probability distributions, uniform distributionand normal distribution, were selected to generate theparameter sets. For example, if the test was being run forthe first time then the test engineer may require getting abroad understanding of where failures may occur. In this casea parameter set with Uniform distribution would be a sensibleselection since it will give an equal probability to each valueInt J Adv Manuf Technol (2010) 51:233246within the test set. Whereas, if after some testing it becameevident that failures occurred around a specific value, then,the parameter sets that need to be generated would have to bebiased around this point. In this case a parameter set withnormal probability distribution where the mean is equal to thefailure parameter value would be a sensible selection.An important requirement for the testing system is theability to repeat a given test sequence so that any actions takento address an identified fault can be reconfirmed. This isextremely useful for post-review and analysis in order toisolate the failure causes. The way to fulfill this requirementwas to use a pseudo-random number generator to generateparameter values. In this project, a LabVIEW softwarepackage (Ver. 8.5) 19 was employed to implement thetransient wave generator. The LabVIEW software libraryprovides a selection of pseudo-random number generatorfunctions which support both uniform and normal probabil-ity distributions. A test set generated by the pseudo-randomnumber generator depends on a seed value, the range andlength of the number, therefore can be regenerated. The seedvalue can be any value within the range. In this work, testsets for each parameter were individually generated by thepseudo-random generator with the same sample size i.e., thenumber length. To cover as many voltage scenarios aspossible, the number length should be as big as possible. Inpractice, it can be set according to the testing time allowedand not overrun the computer memory size.7 System evaluation and experimentsThe testing system developed has been deployed andheavily utilized in JLR. Five different carlines, i.e., RangeRover, XF and Discovery, have been tested with differentversions of software updates. It has been evaluated that anautomated testing using the system developed is four timesfaster than the manual testing and utilizes approximately20% of the resource required for manual regression testingonce test scripts have been developed. Furthermore, thetesting accuracy is dramatically improved with the detectedfailure ratio increased from 5% by manual testing to 12%by the automated testing for the first issue of the softwareof a specific vehicle. Fig. 15 shows a real test setup for aInt J Adv Manuf Technol (2010) 51:233246Fig. 12 Parameterized repre-243sentation of a crank waveformV1fV3T3V2T1T2T4bench test. In this setting, two cameras are employed forinspection of the instrument cluster and the touch screendisplay respectively. The transient waveform generator is anToT2T1embedded version of the system described in Section 6. Thetest automation software was provided by dSPACE as a partOnOffFig. 13 Parameterized representation of the contact bounce waveformof the package of HIL simulator and runs in the host PC,which is not contained in the picture.Figure 16 gives a typical test plan for investigating theimpact of various cranking waveforms on the infotainmentsystem. The test script is created using dSPACE Automa-tionDesk (Ver. 1.5) software. The software allows a real-time control of the Simulink models in the HIL and featuresa drag-pull user interface. Each test cycle corresponds withapplying one mode of cranking voltage to the vehiclesystem. Before starting a test cycle, the testing system andthe Infotainment system under test need to be initialized soFig. 14 Parameterised represen-T0T1T 2T3T4T5tation of the ramp waveformFig. 15 A real testing setup fora bench test0vV1V2V3244that the testing system is ready and original configuration ofthe touch screen can be recorded as a reference. In thebeginning of a test cycle, a CAN message is issued by thesimulator to make the car go to power mode 9 (crankingstate) as discussed in Section 3.1. Meanwhile, a crankingvoltage is created by the Transient Waveform Generatorand applied into the car. The car then goes to normalrunning state and the testing starts, which includes soundchecking and inspections of five different display pages.The right part of the flow chart gives more details on thehome page inspection such as checking the page title,temperature format, clock format, and audio status. Whenan unanticipated pattern occurs, the testing system istrigged to record the failure scenarios including displayimages, MOST traces, and transient waveform parameters.The information is synchronized by test cycle number andtime stamping. These features are extremely useful for post-testing analysis and further investigation. The testingdescribed in Fig. 16 has been continuously run for 100 hwith more than 5,000 test cycles generated. The experi-mental result has shown that the system was highly robustfor a long period of the testing.Int J Adv Manuf Technol (2010) 51:233246Figure 17 gives five screen shots to illustrate theoperation of the testing system. Screenshot 1 shows thetest automation script running in the AutomotionDesk.Screenshot 2 shows the image processing jobs running in theCognex In-sight camera. Screenshot 3 illustrates how thetouch screen are manipulated by the resistive simulationapproach, where the touch screen is divided into 4024 smallsquare areas (grids), each corresponding to a set of resistancevalue. A button within the touch screen may span a number ofgrids. Screenshot 4 shows the system control desk where allsettings and configurations on the unit under test and thetesting system can be done. It can also be used to conductsome manual testing. Screenshot 5 illustrates the status of atransient waveform being applied to the unit under test.8 ConclusionsA system capable of replicating human control andobservation has been developed for automated functionaland robustness testing of a vehicles infotainment system.The system mainly contains four modules including an HILFig. 16 Flow chart of a typicaltest planInitialise dSpace platform and load variable fileInitialise camera, select job0 for homepageinspection, camera on lineInitialise transient voltage generator and selectcrank waveform,.Configure the Unit, record original status(display) of all pages in touch screenSet the MOST analyzer standbyStart a test cycleEnter power mode 9, engine cranking stateApply an cranking voltage, wait for endingEnter power mode 7, engine running stateSound checkingGo to home page and inspect using job 0Go to audio page and inspect using job1Go to climate page and inspect using job2Go to phone page and inspect using job 3Go to navigation page and inspect using job 4Go to vehicle page and inspect using job 5End the test cycleTurn MOST analyzer off, End the testSelect the job 0 for home page inspectionVirtually press the home page soft button in thetouch screenCheck page titleCheck temperature formatCheck clock formatCheck audio status, CD or radioIf CD, check active CD number and tracknumberIf Radio, check radio source and active stationAny failure?if yes, record the image, the cycle number andwaveform parameters, log the MOST messagetrace and increase failure count.If no, continue the test.Int J Adv Manuf Technol (2010) 51:2332462451. Test script runningin Automation
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