My Note for MatlabSimulink.docx

My Note for MatlabSimulink.docx

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MyNoteforMatlabSimulink

HydraulicSimulationUsingSimulink

1.Simulink-S-PSandPS-SConverter

（1）S-PSconverter

It’sfunctionisconvertingsimulink（S）signalintophysical（P）signal.

（2）PS-Sconverter

IthastheoppositefunctiontoS-PS.

Youcanlookatthefollowingdiagram.

2.Asimplesymbol

”~=”meansunequal.

3.Switchblock（signalrouting）

Theswitchblockpassesthroughthefirstinputorthethirdinputbasedonthevalueofthesecondinput.Thefirstandthirdinputsarecalleddatainputs.Thesecondinputiscalledcontrolinput.Specifytheconditionunderwhichtheblockpassedthefirstinputbyusingthecriteriaforpassingfirstinputandthresholdparameters.

Selecttheconditionunderwhichtheblockpassesthefirstinput.Ifthecontrolinputmeetstheconditionsetinthecriteriaforpassingfirstinputparameter,theblockpassesthefirstinput.Otherwise,theblockpassesthethirdinput.

☺自己的对switch模块的理解：

（1）中间端口（port2）是判定，另外两个端口（port1andport3）是输入。

（2）在模块设置中选择判定条件（数据输入）：

默认选择是u>=threshold，可以设定门限值。

如果设定门限值为0，然后判断port2的输入与0的大小关系，若port2>=0，则输出port1的输入；若port2<0，则输出port3的输入。

如果选择判断条件为u>threshold，结果类似。

如果选择判断条件为u~=0（意思是非零），若port2非零，则输出port1的输入；若port2为零，则输出port3的输出。

（3）若port2输入是布尔运算输入（Booleancontrolinput）：

若port2的布尔运算结果为1，则输出port1的输入；

若port2的布尔运算结果为0，则输出port3的输入。

（4）Example

下面举个例子，将一个简单的判断语句用switch模块来表示。

Ifa>1

b=3;

else

b=5;

end

4.ConnectionofSimulinkandMatlab

（1）由Matlab工作空间变量设置Simulimk模块参数：

一般情况下可以通过打开模块参数设置对话框来设置参数，但是当参数比较多时，就比较麻烦了。

如果各个参数有一定的函数关系，那么就更适合这种方法了。

具体过程如下：

A.将模块中的参数用字母表示，比如k，然后其他的参数写成关于k的函数；

B.在工作空间中给定k一个值，那么模块就会自动从工作空间中读取参数的值。

Example:

（2）将信号输出到Matlab工作空间中：

一般是使用scope示波器显示输出结果，但这只能定性的分析输出结果，要想定量的分析且希望把几组结果画在同一张图中进行比较，就需要（三种方法：

a.使用ToWorkspace模块;b.在示波器模块设置中将数据输出到工作空间；c.使用SimulinkConfigurationParameter对话框中的Dataimportandexport）先将数据输出到工作空间中，然后再进行数据处理（我习惯于用Origin进行数据分析和画图）。

Example:

（3）使用Matlab工作空间变量作为系统的输入信号：

使用FromWorkspace模块可以将Matlab工作空间中的变量作为Simulink系统仿真模块的输入信号。

Example:

t=[036910];

x=[-11-111/3];

input=[t’,x’];

系统输入是一个三角波，从结果可以看出Simulink对Matlab工作空间中的input进行了线性插值。

（4）调用M文件中定义的参数（自己摸索出来的）：

在一个M文件中罗列定义出simulink模型中所要用到的参数，然后在运行simulink模块之前，先运行M文件，这样参数就写入matlab工作空间中，然后再运行simulink系统仿真。

Example:

点击

运行M文件；

然后运行simulink系统仿真

Warning：

根据个人试验，M文件和simulink模型不能取相同的名字，原因可能是simulink运行时会自动产生一个同名文件，如果M文件取相同的名字，则可能会引起冲突。

（Iamnotsure.Ijusttakesometentativetest.）。

并且M文件命名时，名字里面不可以有“空格键”，要不然M文件没法运行（可能这只是一个很小的知识点，但是花了我好长时间才摸索出来）。

5.HydraulicCircuitwithLoad-SensingVelocityControl

Thecircuitisequippedwiththeload-sensingvelocityregulatorinstalledbetweenthepumpanddirectionalvalve.Unlikeaconventionalmeter-invelocitycontrol,theload-sensingdeviceautomaticallyadjustsoutputpressureofthepumpinsuchawaythatitequalsthesumofthepresetpressuredropacrossthepressure-compensatedflowcontrolvalveandthepressureinducedbyload.Thepilot-operatedpressure-reliefvalveintheload-sensingblockisbuiltofthePoppetValveandtheHydraulicDouble-ActingValveActuatorblocks.

6.CreatingaSimpleModel

BuildingaSimHydraulicsDiagram

ModifyingInitialSettings

RunningtheSimulation

AdjustingtheParameters

BuildingaSimHydraulicsDiagram

Inthisexample,youaregoingtomodelasimplehydraulicsystemandobserveitsbehaviorundervariousconditions.Thistutorialillustratestheessentialstepstobuildingahydraulicmodel,describedintheprevioussection,andmakesyoufamiliarwithusingthebasicSimHydraulicsblocks.

Thefollowingschematicrepresentsthemodelyouareabouttobuild.Itcontainsasingle-actinghydrauliccylinder,whichiscontrolledbyanelectricallyoperated3-waydirectionalvalve.Thecylinderdrivesaloadconsistingofamass,viscousfriction,andpreloadedspring.

Thepowerunitconsistsofamotor,apositive-displacementpump,andapressurereliefvalve.Dependingonitscharacteristics,suchapowerunitcanbemodeledinavarietyofways,asdescribedinModelingPowerUnits.Inthisexample,thepumpunitisassumedtobepowerfulenoughtomaintainconstantpressureatthevalveinlet.Therefore,wearegoingtorepresentitinthediagrambyaHydraulicPressureSourceblock.

TocreateanequivalentSimHydraulicsdiagram,followthesesteps:

1.OpentheSimscapeandSimulinkblocklibraries,asdescribedinIntroducingtheSimHydraulicsBlockLibraries.

2.Createanewmodel.Todothis,clicktheNewbuttonontheLibraryBrowser'stoolbarorchooseNewfromthelibrarywindow'sFilemenuandselectModel.Thesoftwarecreatesanemptymodelinmemoryanddisplaysitinanewmodeleditorwindow.

Note  Alternately,youcantypessc_newattheMATLABCommandprompt,tocreateanewmodelprepopulatedwithcertainrequiredandcommonly-usedblocks.Formoreinformation,seeCreatingaNewSimscapeModel.

3.OpentheSimscape>FoundationLibrary>Hydraulic>HydraulicSourceslibraryanddragtheHydraulicPressureSourceblockintothemodelwindow.

4.OpentheSimscape>SimHydraulics>HydraulicCylinderslibraryandplacetheSingle-ActingHydraulicCylinderblockintothemodelwindow.

5.Tomodelthevalve,opentheSimscape>SimHydraulics>Valveslibrary.Placethe3-WayDirectionalValveblock,foundintheDirectionalValvessublibrary,andthe2-PositionValveActuatorblock,foundintheValveActuatorssublibrary,intothemodelwindow.

6.Connecttheblocksasshowninthefollowingillustration.

7.PortsToftheHydraulicPressureSourceand3-WayDirectionalValveblockshavetobeconnectedtothetank,atatmosphericpressure.Tomodelthisconnection,opentheSimscape>FoundationLibrary>Hydraulic>HydraulicElementslibraryandaddtheHydraulicReferenceblocktoyourdiagram,asshownbelow.Todothis,connecttheonlyportoftheHydraulicReferenceblocktoportToftheHydraulicPressureSourceblock,thenright-clickthisconnectionlinetocreateabranchingpoint,andconnectthispointtoportTofthe3-WayDirectionalValveblock.

8.Modelthemechanicalloadforthecylinder.OpentheSimscape>FoundationLibrary>Mechanical>TranslationalElementslibraryandaddtheMass,TranslationalSpring,TranslationalDamper,andthreeMechanicalTranslationalReferenceblockstoyourdiagram.

Toindicatethatthecylindercaseisfixed,connectportCoftheSingle-ActingHydraulicCylinderblocktooneoftheMechanicalTranslationalReferenceblocks.TorotatetheMechanicalTranslationalReferenceblock,selectitandpressCtrl+R.YoucanalsoshortentheblocknametoMTRtomakethediagrameasiertoread.

ConnecttheotherblockstoportRoftheSingle-ActingHydraulicCylinderblock,asshownbelow.

9.Nowyouneedtoaddthesourcesandscopes.TheyarefoundintheregularSimulinklibraries.OpentheSimulink>SourceslibraryandcopytheConstantblockandtheSineWaveblockintothemodel.ThenopentheSimulink>SinkslibraryandcopytwoScopeblocks.RenameoneoftheScopeblockstoValve.Itwillmonitorthevalveopeningbasedontheinputsignalvariation.TheotherScopeblockwillmonitorthepositionofthecylinderrod;renameittoPosition.

10.Double-clicktheValvescopetoopenit.Inthescopewindow,clicktoaccessthescopeparameters,changeNumberofaxesto2,andclickOK.Thescopewindownowdisplaystwosetsofaxes,andtheValvescopeinthediagramhastwoinputports.

11.EverytimeyouconnectaSimulinksourceorscopetoaSimHydraulicsdiagram,youhavetouseanappropriateconverterblock,toconvertSimulinksignalsintophysicalsignalsandviceversa.OpentheSimscape>UtilitieslibraryandcopytwoSimulink-PSConverterblocksandtwoPS-SimulinkConverterblocksintothemodel.Connecttheblocksasshownbelow.

12.Tospecifythefluidproperties,addtheHydraulicFluidblock,foundintheSimscape>SimHydraulics>HydraulicUtilitieslibrary,toyourdiagram.YoucanaddthisblockanywhereonthehydrauliccircuitbycreatingabranchingpointandconnectingittotheonlyportoftheHydraulicFluidblock.

13.EachtopologicallydistinctphysicalnetworkinadiagramrequiresexactlyoneSolverConfigurationblock,foundintheSimscape>Utilitieslibrary.Copythisblockintoyourmodelandconnectittothecircuit,similartotheHydraulicFluidblock.Yourdiagramnowshouldlooklikethis.

14.Yourblockdiagramisnowcomplete.Saveitassimple_hydro1.mdl.

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ModifyingInitialSettings

Afteryouhaveputtogetherablockdiagramofyourmodel,asdescribedintheprevioussection,youneedtoselectasolverandprovidethecorrectvaluesforblockparameters.Alltheblockshavedefaultparametervaluesthatallowthemtorun"outofthebox,"butyoumayneedtochangesomeofthemtosuityourparticularapplication.

Toprepareforsimulatingthemodel,followthesesteps:

1.SelectaSimulinksolver.Onthetopmenubarofthemodelwindow,selectSimulation>ConfigurationParameters.TheConfigurationParametersdialogboxopens,showingtheSolvernode.

UnderSolveroptions,setSolvertoode15s（Stiff/NDF）andMaxstepsizeto0.2.

AlsonotethatSimulationtimeisspecifiedtobebetween0and10seconds.Youcanadjustthissettinglater,ifneede

ClickOKtoclosetheConfigurationParametersdialogbox.

2.Selectafluid.Double-clicktheHydraulicFluidblock.IntheBlockParametersdialogbox,setHydraulicFluidtoSkydrol5andsettheotherblockparametersasshownbelow.

ClickOKtoclosetheBlockParametersdialogbox.

3.Specifytheunitsforthepressureinputsignal.Simulinksignalsareunitless.Whenyouconvertthemtophysicalsignals,youcansupplyunitsbyusingtheconverterblocks.Double-