4
3. Steady-State Errors ) s ( E ) s ( R ) s ( G c ) s ( G p ) s ( C ) s ( N ) s ( R ) G G 1 ( G G ) s ( C p c p c ) s ( R ) G G 1 ( 1 ) s ( E p c ) s ( N ) G G 1 ( G ) s ( C p c p n Final value theorem: )] s ( sX [ lim ) t ( x lim x 0 s t ss c c c D N G p p p D N G R N N D D D D ) s ( E p c p c p c N N N D D N D ) s ( C p c p c p c n t ) t ( r Step input t ) t ( r At ) t ( r Ramp input t ) t ( r 2 t 2 A ) t ( r Parabolic input s A ) s ( R 2 s A ) s ( R 3 s A ) s ( R 1 3

3. Steady-State Errors

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R. (. s. ). Step input. Ramp input. Parabolic input. Final value theorem:. 3. Steady-State Errors. R. (. s. ). Step. Ramp. Parabol. Final value theorem:. Step. Ramp. Parabol. e ss :. Step. Ramp. Parabol. [c n ] ss :. Example 3.1 a). Sistem type: 0. Stability test. R. - PowerPoint PPT Presentation

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Page 1: 3.  Steady-State Errors

3. Steady-State Errors

)s(E)s(R )s(Gc )s(Gp)s(C

)s(N )s(R)GG1(

GG)s(C

pc

pc

)s(R)GG1(

1)s(E

pc

)s(N)GG1(

G)s(C

pc

pn

Final value theorem: )]s(sX[lim)t(xlimx

0stss

c

cc D

NG

p

pp D

NG R

NNDD

DD)s(E

pcpc

pc

N

NNDD

ND)s(C

pcpc

pcn

t

)t(r

Step input

t

)t(r At)t(r

Ramp input

t

)t(r2t

2

A)t(r

Parabolic input

s

A)s(R

2s

A)s(R 3s

A)s(R

13

Page 2: 3.  Steady-State Errors

)s(E)s(R )s(Gc )s(Gp)s(C

)s(N

pc K)s(G

)10s3s(

)10s()s(G

2p

RGG1

1)s(E

pc

Final value theorem: )]s(sX[lim)t(xlimx0st

ss

23

0spcpc

pcss R

NNDD

DDse

)K1(

A

p ess:

Step Ramp Parabol

s

A2s

A3s

AStep Ramp Parabol

Example 3.1 a)

NGG1

G)s(C

pc

pn

0s

pcpc

pc

ssn

NNNDD

NDs

]c[

pK Sistem type: 0

0sp2

2

R)10s)(K()10s3s)(1(

)10s3s)(1(s

0sp2

R)10s)(K()10s3s)(1(

)10s)(1(s

)K1(

A

p [cn]ss:

Step Ramp Parabol

Stability test

Page 3: 3.  Steady-State Errors

)s(E)s(R )s(Gc )s(Gp)s(C

)s(N

s

KsK

s

KK)s(G ipipc

)10s3s(

)10s()s(G

2p

33

0spcpc

pcss R

NNDD

DDse

0sip2

2

R)10s)(KsK()10s3s(s

)10s3s(ss

iK

A0 ess:

Step Ramp Parabol

Example 3.1 b)

System type: 1

Integral control improves error performance

sKK)s(G dpc

)K1(

A

p ess:

Step Rampa Parabol

System type: 0

Derivative control does not change error performance

Page 4: 3.  Steady-State Errors

)s(E)s(R )s(Gc )s(Gp)s(C

)s(N

pc K)s(G

)10s3s(s

)10s()s(G

22p

43

0spcpc

pcss R

NNDD

DDse

0sp234

234

R)10s)(K()s10s3s)(1(

)s10s3s)(1(s

Example 3.1 c)

pK

A0 0ess:

Step Ramp Parabol System type: 2

DcDp de s0 System type: 0

DcDp de s1 System type: 1 DcDp de s2 System type: 2

DcDp de s3 System type: 3

sse Overshoot sst rt

pK

iK 0

dK