MBSDLecture 2010-Braking Controller

1AdvancedModel-Based-SystemDesignLecture10:Lecture10:BrakesPart2:BrakeControllerIncorporatingtheBrakeModel•Nowthatwehaveamechanicalfrictionbrakemodel,weneedtoincorporatethebrakemdoelintoourvehicle.Thiswillrequirethreesteps:2–Connectingthebrakestothehalf-shafts–Modifyingthedrivermodeltoemitaccelerationandbrakingsignals.–Designingabrakecontrollersochoosebetweenthefoundationbrakes(mechanicalfrictionbrakes)andtheregenbraking(theelectricmotor).theregenbraking(theelectricmotor).Copyright2009Rose-HulmanInstituteofTechnology.2ConnectingtheBrakes•Thebrakesareconnectedtotherearhalf-shafts(theshaftsbetweenthereardifferentialandthewheels3differentialandthewheels.•WewillstartwithmodelLectue9_Model3thatwemodifiedinLecture9andimprovedthesimulationspeed.•SavethismodeasLecture10_Model1.•Addthemechanicalbrakesasshown:4Copyright2009Rose-HulmanInstituteofTechnology.3ConnectingtheBrakes•Thebrakemodelhas:–Beenresizedtofitinasmallspace.–TwoInportsthatarelabeledas“1”:5pInport1.Inport1.Inports•WenoticethatbothInportsarelabeledasport1.–Thismeansthattheportsarethesameport6–Thismeansthattheportsarethesameport.ÎTheRearDiffandBodysubsystemwillonlyhaveasingleSimulink(nottwo).–WecanusetheseduplicatedInportsinsteadofusingFromandGotoblocks.–Theduplicatedportwascreatedusingthe–Theduplicatedportwascreatedusingthefollowingprocedure.Copyright2009Rose-HulmanInstituteofTechnology.4Inports•PlaceasingleInportinyourdrawing:7Inport1addedhere.addedhere.Inport1notaddedhere.Inports•Right-clickanddragtheInportyouwanttoduplicate:8Right-clickonthisRightclickonthisInportanddragitsomewhere.DraggedInport:Copyright2009Rose-HulmanInstituteofTechnology.5Inports•Dragtheportnexttothelowerbrake9subsystemandreleasethemousebutton.•SimulinkwillaskifyouwanttoCfCopyofDuplicatetheport.Inports•SelectingCopywillcreateanewport(number2inthiscase)andwillnameitwiththesamenameastheoriginalportandappenda1tothe10name.•SelectingDuplicateInportwillcreateaportwiththesamenumber(1inthiscase)andwillnameitwiththesamenameastheoriginalportandappenda1tothename.•Duplicatingaportdoesnotcreateanewport.ItcreatesaconnectiontoanexistingportwithoutusingFromandGotoblocks.Copyright2009Rose-HulmanInstituteofTechnology.6Inports•SelectDuplicateInportandconnecttheportasshown:11Inports•Whenwegotop-levelblockdiagram,wewillseethattheRearDiffandBodysubsystemonlyhasasingleBrake_Requestinput:12SingleSimulinkinput.Copyright2009Rose-HulmanInstituteofTechnology.7DriverModel•Wenowneedtoupdatethedriversubsystem.•Thedriverblockknowswhatthedesiredandactualvehiclespeedsareandemitsthedrivertorque13pqrequesttotrytomaketheactualvehiclespeedequalthedesiredspeed:–Theemitteddrivertorquerequestisanumberbetween-1and+1.–Ifthevehiclespeedistooslow,thedriverblockemitsapositivesignaltoacceleratethevehiclepositivesignaltoacceleratethevehicle.–Ifthevehiclespeedistoohigh,thedriverblockemitsanegativesignaltodeceleratethevehicle.DriverModel•Thus,weseethatpositivedrivertorquerequestsareaccelerationrequestsandnegativetorquerequestsarebrakingrequests14negativetorquerequestsarebrakingrequests.•Wecaneasilysplitthedrivertorquerequestintotwoseparatesignals:–Thedriveracceleratorrequestwhicharethepositivevaluesofthedrivertorquerequestsignal.–Driverbrakerequestwhicharethenegativevaluesofthedrivertorquerequest.Copyright2009Rose-HulmanInstituteofTechnology.8DriverModel•Wewillusesaturationblockstosplitthesignalinhalf.TheDriver_Accel_Requestisthepositiveportionsofthedrivertorquerequestsignal.15Drivertorquerequestsignal.Ithasbothpositiveandnegativevalues.Driver_Accel_Requestsarealwayspositive.Thesatblockpassesonlythepositiveportionsofthedrivertorquerequest.DriverModel•TheDriver_Brake_Requestsignalisthenegativeportionsofthedrivertorquerequestsignal.16Driver_Brake_Requestsarealwayspositive.Thesatblockpassesonlythenegativeportionsofthedrivertorquerequestandthenwemultiplyby-1becausethebrakemodelrequiresapositivesignalaswell.Copyright2009Rose-HulmanInstituteofTechnology.9DriverSignals•Notethat:–ApositivevalueintheDriver_Brake_Requestmeansslowdownthevehicle.17meansslowdownthevehicle.–ApositivevalueintheDriver_Accel_Requestmeansspeedupthevehicle.•ThesetwosignalsareonestepinpreparingourmodelfortheHardware-in-the-Loop(HIL)iltiilldlththtsimulationswewilldolaterwherethesetwoinputswillcomefromactualbrakeandaccelerationpedals.DriverBlock•Alsonotethatourdriverblocknowhasasingleoutput.–TheDriverAccelRequestand18–TheDriver_Accel_RequestandDriver_Brake_RequestsignalsarenotcontainedintheVehicle_System_Diagnosticsbus.Copyright2009Rose-HulmanInstituteofTechnology.10BrakeController•Themeatofthissectionisthedevelopmentofabrakecontroller.•Wehavebothregenbrakes(usingtheelectric19g(gmotortoslowdownthevehicle)andfoundationbrakes(mechanicalfrictionbrakes).•Foundationbrakesresultin100%energylossÆallofthebrakingenergygoesintogeneratingheat.•Regenbrakingallowsyoutorecapturesomeofthevehicleskineticenergyandstoreitinthebattery.BrakeController•Severaldifferentconcernswillbeincludedinourbrakingcontrolstrategy:–Fuelefficiency–Wewillcreateastrategythatusesregenbrakingbeforefoundatio