大三上自控原理three.pptx

Chapter3Theperformanceoffeedbackcontrolsystems重点掌握：1、一、二阶系统时域性能指标的定义和计算2、Routh-Hurwitz稳定性判据3、系统稳态误差的计算。

Typicaltestsignalsforthetimeresponseofcontrolsystems.Theunit-stepresponseandtime-domainspecifications.Timeresponseoffirst-orderandsecond-ordersystems.Improvementperformanceofsecondsystems.5.Conditionforafeedbacksystemtobestable6.Routh-hurwitzcriterion7.Thesteady-stateerroroffeedbackcontrolsystem.Maincontents

1.Unitimpulsefunction00tTypicaltestsignalsforthetimeresponseofcontrolsystems.

2.Unitstepfunction10t103.Unitrampfunctiont00

4.Unitparabolicfunction0t0

Theunit-stepresponseandtime-domainspecificationsUnit-stepresponse:Theresponseofacontrolsystemwhentheinputisaunit-stepfunction.Time-domainspecifications1.超调量（Percentovershoot）：指响应超出稳态值的最大偏离量与稳态值之比。

6.稳态误差(steady-stateerror）：期望值与稳态值之差，2.上升时间（risetime）：指单位阶跃响应曲线，从稳态值的10%上升到90%所需要的时间（也有指从零上升到稳态之所需要的时间）。3.调节时间（settlingtime）：在单位阶跃响应曲线的稳态值附近，取（或）作为误差带，响应曲线达到并不在超出该误差带的最小时间。4.延迟时间(delaytime)td：指响应曲线第一次达到其终值一半所需的时间。5.峰值时间(Peaktime)tp：指响应超过其终值到达第一个峰值所需的时间。

Timeresponseofafirst-ordersystemAssumethetransferfunctionofafirst-ordersystemisTheunitstepresponseforthissystemwhen

ResponseduetounitstepsignalT=2T=6

Timeresponseofasecond-ordersystemTheunitstepresponseforthissystem

jwherewhenunderdamped

NaturalfrequencyDampingratioDampedfrequency

criticallydampedundamped

overdampednegativelydampedThesystemisunstable.

例已知单位负反馈系统的开环传递函数为试计算系统在单位阶跃信号作用下,当分别取200、1500、13.5时，响应的性能指标：

Improvementperformanceofasecondsystem(1).VelocityfeedbackcontrolofoutputwhereR(s)E(s)k1sC(s)--

(2).Theproportion-differentialcontroloferrorsignalR(s)E(s)1TdsC(s)-where

Effectsofthirdpoleandazeroonthesecond-ordersystemresponseTheresponseofathird-ordersystemcanbeapproximatedbythesecond-ordersystem.

Theresponseforthes