chapter2-2.ppt

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1、ThreebasicformsG1G2G2G1G1G2G1G2G1G2G1G1G21+cascadeparallelfeedback2.6blockdiagrammodels(dynamic)2.6.2.2blockdiagramtransformationsbehindablockx1yG±x2±x1x2yGGAheadablock±x1x2yGx1yG±x21/G1.Movingasummingpointtobe:2.6blockdiagrammodels(dynamic)2.Movingapickoffpointtobe:behindab

2、lockGx1x2yGx1x2y1/GaheadablockGx1x2yGGx1x2y2.6blockdiagrammodels(dynamic)3.Interchangingtheneighboring—Summingpointsx3x1x2y＋－x1x3y＋－x2Pickoffpointsyx1x2yx1x22.6blockdiagrammodels(dynamic)4.Combiningtheblocksaccordingtothreebasicforms.Notes:1.Neighboringsummingpointandpickoff

3、pointcannotbeinterchanged！2.Thesummingpointorpickoffpointshouldbemovedtothesamekind！3.Reducetheblocksaccordingtothreebasicforms！Examples:MovingpickoffpointG1G2G3G4H3H2H1abG41G1G2G3G4H3H2H1Example2.17G2H1G1G3MovingsummingpointMovetothesamekindG1G2G3H1G1Example2.18G1G4H3G2G3H1

4、DisassemblingtheactionsH1H3G1G4G2G3H3H1Example2.19Chapter2mathematicalmodelsofsystems2.7Signal-FlowGraphModelsBlockdiagramreduction——isnotconvenienttoacomplicatedsystem.Signal-Flowgraph—isaveryavailableapproachtodeterminetherelationshipbetweentheinputandoutputvariablesofasys

5、-tem,onlyneedingaMason’sformulawithoutthecomplexreduc-tionprocedures.2.7.1Signal-FlowGraphonlyutilizetwographicalsymbolsfordescribingtherelation-shipbetweensystemvariables。Nodes,representingthesignalsorvariables.Branches,representingtherelationshipandgainBetweentwovariables.

6、Gb2.7Signal-FlowGraphModelsExample2.20:x4x3x2x1x0hfgedca2.7.2sometermsofSignal-FlowGraphPath—abranchoracontinuoussequenceofbranchestraversingfromonenodetoanothernode.Pathgain—theproductofallbranchgainsalongthepath.2.7Signal-FlowGraphModelsLoop——aclosedpaththatoriginatesandte

7、rminatesonthesamenode,andalongthepathnonodeismettwice.2.7.3Mason’sgainformulaLoopgain——theproductofallbranchgainsalongtheloop.Touchingloops——morethanoneloopssharingoneormorecommonnodes.Non-touchingloops—morethanoneloopstheydonothaveacommonnode.2.7Signal-FlowGraphModels2.7Sig

8、nal-FlowGraphModelsExample2.21x4x3x2x1x0hfgedcba2.7Signal-FlowGraphModels2.