Nguyễn Công Phương

CONTROL SYSTEM DESIGN

State Variable Models

Contents

Introduction

I. II. Mathematical Models of Systems III. State Variable Models IV. Feedback Control System Characteristics V. The Performance of Feedback Control Systems VI. The Stability of Linear Feedback Systems VII. The Root Locus Method VIII.Frequency Response Methods IX. Stability in the Frequency Domain X. The Design of Feedback Control Systems XI. The Design of State Variable Feedback Systems XII. Robust Control Systems XIII.Digital Control Systems

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2

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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3

The State Variables of a Dynamic System (1)

• The state of a system is a set of variables

whose values, together with the input signals & the equations describing the dynamics, will provide the future state & output of the system.

• The state variables describe the present

configuration of a system & can be used to determine the future response, given the excitation inputs & the equations describing the dynamics.

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4

The State Variables of a Dynamic System (2)

Wall friction b

M b ky t ( ) u t ( )   

2 d y t ( ) 2 dt

k

y t ( ),

x t ( ) 1

x t ( ) 2

dy t ( ) dt

Mass M

dy t ( ) dt

2

y(t)

u(t)

M

bx

u t ( )

2

kx 1

dx 2 dt

x 

2

C

u t ( )

i

x u     x 1 k M 1 M b M dx 1 dt dx 2 dt      

i c

L

2

dv C dt

x u t ( )   

L

Li C

R

1 C 1 C

L

Ri

 

2

v C

L

 Cv 

( )u t

Ci

t ( )

di L dt 

x   x 1 1 L R L dx 1 dt dx 2 dt  ov 

x

i

2

v o x 1

Ri L v ,C

2

L

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5

Rx  v t ( ) o          

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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6

The State Differential Equation (1) ...  

...  

...  

...  

x  1 x 

a x 11 1 a x 21 1

a x 12 2 a x 22 2

a x 1 n n a x 2 n n

b u 11 1 b u 21 1

b u 1 m m b u 2 m m

2

...  

...  

n

a x 1 1 n

a x 2 2 n

a x nn n

b u 1 1 n

b u nm m

       x  

x 1 x

a 11 a

a 1 n a

a 12 a

x 1 x

n

d dt

b b  11 1 m    b b  nm n 1

u 2  u m

    

         

    

2  x

21  a

2  x

  22 2    a a 

n

n 1

nn

n

2

n

     

     

     

           

     

x Ax Bu    y Cx Du 

 

t

t

x

t ( )

exp(

A x t

) (0)

exp[

A

(

t

)

Bu

t

)

r d ( ) 

( ) 

d 

t ( ) (0) Φ x

( Φ

Bu

0

0

1

1

X

[

s

 I A x ]

(0)[

 I A BU s ]

s ( )

 s ( )

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7

The State Differential Equation (2)

x

u t ( )

 

2

1 C

1 C

x

x 1

2

1 L

R L

dx 1 dt dx 2 dt

L

Li C

R

Rx

 Cv 

v t ( ) o

2

        

( )u t

Ci

 ov 

0 

x u t ( )   x 

1 C 0        

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8

1   C  R   L  x R    1   L   0         y 

The State Differential Equation (3)

q

p

1k

2k

u

f

f

u  

M a 1 1

spring

damp

M2

M1

)

(

)

 

M p  1

u k p q ( 1

b p q   1

1b

2b

 



M p b p k p 1

1

1

u k q b q  1 1

(

)

(

)

M q  2

k p q 1

b p q   1

k q b q   2

2

(

(

M q  2

k 1

k q ) 2

b 1

b q )  2

k p b p   1

1

p

,

q

x 3 x

x  1 x 

p  q 

2

4

2

x  1  x  

  

 b 1 M

1

1

1

p u q     p     p  q  x  3 k 1 M 1 M k 1 M b 1 M

2

4

1 b  1 M

2

2

2

2

1 k  1 M sites.google.com/site/ncpdhbkhn

9

k b 2 q p    q  p  x  q     k 1 M b 1 M       

The State Differential Equation (4)

1

1

1

p u q     p     p  q  x  3 k 1 M b 1 M 1 M k 1 M b 1 M

2

4

1 k  1 M

1 b  1 M

2

2

2

2

k b 2 q p    q  p  x  q     k 1 M b 1 M      

  p

,

2

4

2

x

u

x

 

x  3

x 1

2

x 3

4

k 1 M

k 1 M

b 1 M

b 1 M

1 M

1

1

b 2

2

x

x

x 

4

4

x 1

2

x 3

k 1 M

1 k k  1 M

1 b 1 M

1 b  1 M

2

2

2

2

      

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10

q x 3 x   x  1 x  p  q  x  1  x     

4

2

The State Differential Equation (5) b 1 M

1

1

u x x       x 3 x  3 x 1 k 1 M k 1 M b 1 M 1 M

2

4

4

2

1 k k  1 M

1 b 1 M

1 b  1 M

2

2

2

2

0

0

b 2 x x     x  x 1 x 3 k 1 M      

A

,

B

x

,

0 0 k 1 M

0 0 k 1 M

1 0 b 1 M

0 1 b 1 M

1

1

1 M

1

k

x 1 x 2 x 3 x

2

b 2

4

p     q     p    q   

     

     

0

        

       

k 1 M

1 k  1 M

b 1 M

1 b  1 M

2

2

2

2

         

        

x Ax B u   

y

p  

x Cx

 1 0 0 0

x 1

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11

The State Differential Equation (6)

q

p

1k

2k

u

M2

M1

1b

2b

x

u

x

 

x  3

x 1

2

x 3

4

k 1 M

k 1 M

b 1 M

b 1 M

1 M

1

1

b 2

2

x

x

x 

4

4

x 1

2

x 3

k 1 M

1 k k  1 M

1 b 1 M

1 b  1 M

2

2

2

2

     

p

q

)

)

p

u

M2

M2

)

)

p 

k p q 1( b p q 1( 

2k q 2b q

k q 1( b q 1(

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12

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram

Models

4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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13

Signal – Flow Graph & Block Diagram Models (1)

L

x

u t ( )

 

2

1 C

1 C

Li C

R

 ov 

( )u t

Ci

x

x 1

2

1 L

R L

dx 1 dt dx 2 dt

R L

1 L

1 s

R

1 C

Rx

v t ( ) o

2

        

( )U s

 Cv 

?

oV s ( )

1/ s

1X

2X

2

1 C

oV s ( ) U s ( )

G s ( )  

( )

( )U s

1X

oV s ( )

R

1 L

R L 2X1 s

1 s

1 C

( )

1 C

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14

LC ) s ( ) /( R LC R L s ) / 1/(  

Signal – Flow Graph & Block Diagram Models (2)

m

m

1 

b m

G s ( )

,

n m 

( ) Y s U s ( )

b s m n s

 a

s 1  1 n  s

...   ...  

n

b s b  1 0 a s a  1

0

1 

n m

)

(

1)

1)

n

(  

n m   

( n  

b s m

b m

b s 0

 n

s 1  1  s

 s a 

...  

b s 1 1) 

n

...   ( n   a s 1

a s 0

1 

P k

k

N

Sum of the forward-path factor 1 sum of the feedback loop factors 

1

L q

  

q

1 

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15

Signal – Flow Graph & Block Diagram Models (3)

Ex. 1

4

G s ( )

4

3

1

3

4

2

b s 0 2 

Y s ( ) U s ( )

s

1

a s 3

a s a  1

0

a s 3

a s 2

a s 1

a s 0

b 0 a s 2

4

3

2

)

a s 2

s (   4

 3

d

)

d

d

)

)

(

)

a

a

/

)

u

3

2

a y b ( 0

0

a 1

d y b / 0 dt

a s a Y s ( ) 1 0 2 y b / ( 0 3 dt

b U s ( ) 0 y b / ( 0 2 dt

4X

1

1 s

1 s

1 s

1 s

0b

( )U s

( )Y s

x 1 x

a s 3 y b / ( 0 4 dt y b / 0 

3X

2X

1X

2

3a

2a

1a

x 3 x

0a

4

x  1 x  2 x  3

y b /  0 y b /  0 y b /  0

4X

3X

2X

1X

( )Y s

( )U s

0b

1 s

1 s

1 s

1 s

1 s

( )

( )

3a

2a

( )

1a

0a

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16

Signal – Flow Graph & Block Diagram Models (4)

Ex. 1

4

G s ( )

4

3

1

3

4

2

b s 0 2 

Y s ( ) U s ( )

s

1

a s 3

a s a  1

0

a s 3

a s 2

a s 1

a s 0

b 0 a s 2

4

3

2

d

)

d

)

d

)

)

(

a

a

/

)

u

3

2

a 1

a y b ( 0

0

/ d y b 0 dt

( y b / 0 4 dt

( y b / 0 3 dt

( y b / 0 2 dt

x 1 x

y b / 0 

2

x 3 x

4

x  1 x  2 x  3

y b /  0 y b /  0 y b /  0

u

x     4

a x 0 1

a x 1 2

a x 2 3

a x 3 4

y

b x 0 1

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17

Signal – Flow Graph & Block Diagram Models (5)

Ex. 1

4

G s ( )

4

3

1

3

4

2

b s 0 2 

Y s ( ) U s ( )

s

1

a s 3

a s a  1

0

a s 3

a s 2

a s 1

a s 0

b 0 a s 2

u

 

x 

4

a x 0 1

a x 1 2

a x 2 3

a x 3 4

y

b x 0 1

u t ( )

x Ax B u   

0 0 0 a

0 0 0 a

0 0 0 a

x 1 x 2 x 3 x

x  1 x  2 x  3 x 

0 0 0 a 1

0

2

3

4

4

0     0     0   1  

     

     

     

     

     

     

x 1 x

y t ( )

Cx

0 0 0

b 0

2 x 3

     

     

x 4 sites.google.com/site/ncpdhbkhn

18

Signal – Flow Graph & Block Diagram Models (6)

Ex. 1

4

G s ( )

4

3

1

3

4

2

b s 0 2 

Y s ( ) U s ( )

s

1

a s 3

a s a  1

0

a s 3

a s 2

a s 1

a s 0

b 0 a s 2

4X

1

1 s

1 s

1 s

1 s

0b

( )U s

( )Y s

3X

2X

1X

3a

2a

1a

0a

P k

k

G s ( )

N

Y s ( ) U s ( )

Sum of the forward-path factor 1 sum of the feedback loop factors 

1

L q

  

q

1 

4X

3X

2X

1X

( )Y s

( )U s

0b

1 s

1 s

1 s

1 s

( )

( )

3a

2a

( )

1a

0a

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19

Ex. 2

2

1

3

2

3

4

G s ( )

 1

4

4

 2 

Y s ( ) U s ( )

1

s

b s 2 

b s 3 

Signal – Flow Graph & Block Diagram Models (7) b s  0 3  a s  0

b s b  1 0 a s a   1

b s 2 a s  2

b s 3 a s  3

b s 1 a s  1

 2 a s 2

0

P k

k

G s ( )

N

( ) Y s U s ( )

Sum of the forward-path factor 1 sum of the feedback loop factors 

1

L q

 3 a s 3   

q

1 

3b

2b

4X

1b

1

1 s

1/ s

1/ s

1/ s

0b

( )U s

( )Y s

3X

2X

1X

3a

2a

1a

0a

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20

Ex. 2

1

2

3

3

4

2

G s ( )

 1

4

4

 2 

Y s ( ) U s ( )

1

s

b s 2 

b s 3 

Signal – Flow Graph & Block Diagram Models (8) b s  0 3  a s  0

b s b  1 0 a s a   1

b s 2 a s  2

b s 3 a s  3

b s 1 a s  1

 2 a s 2

 3 a s 3

0

3b

2b

4X

1b

1

1 s

1/ s

1/ s

1/ s

0b

( )U s

( )Y s

3X

2X

1X

3a

2a

1a

0a

X

1

X

2

X

X s / 2 X s / 3 X s / 4

3

X

) /

s

U a X ( 

a X 0

1

2

       Y

4 

3 

4 b X  0

1

3 b X 1

2

a X 2 b X 2

3

a X 1 b X 3

4

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21

Ex. 2

2

1

3

2

3

4

G s ( )

 1

4

4

 2 

Y s ( ) U s ( )

1

s

b s 2 

b s 3 

Signal – Flow Graph & Block Diagram Models (9) b s  0 3  a s  0

b s b  1 0 a s a   1

b s 2 a s  2

b s 3 a s  3

b s 1 a s  1

 2 a s 2

 3 a s 3

0

X

X

sX

1

2

1

X

X

sX

2

3

2

X

X

sX

X s / 2 X s / 3 X s / 4

3

4

3

X

sX

) /

s

)

U a X ( 

U a X ( 

a X 0

1

2

a X 0

1

2

4 

3 

4 

3 

3 b X 1

2

a X 2 b X 2

3

a X 1 b X 3

4

1

4 b X 0

1

3 b X 1

2

a X 2 b X 2

3

a X 1 b X 3

4

       4   Y b X  0

          Y 

0

1

0

0

0

0

0

1

x 1 x

x 1 x

u t ( )

x

2

0

0

1

0

d dt

2 x 3

2 x 3

a

a

a

x

x

0

a 1

3

4

4

0     0     0   1  

     

     

     

     

     

     

x 3 x

4

a x 0 1

2 x 1 x

y t ( )

b 0

b 1

b 2

b 3

x  1 x  2 x  3 u a x   3 4 b x 1 2

b x 0 1

a x 2 3 b x 2 3

a x 1 2 b x 3 4

       x   4   y 

2 x 3

x

4

     

     

              sites.google.com/site/ncpdhbkhn

22

Ex. 2

2

3

G s ( )

4

Signal – Flow Graph & Block Diagram Models (10) Y s ( ) U s ( )

s

b s 2 

b s 3 

b s b  1 0 a s a   1

 2 a s 2

 3 a s 3

0

3

2

G s ( )

.

4

Y s ( ) U s ( )

( ) Z s Z s ( )

s

b s 3 

b s 2 

 3 a s 3

 2 a s 2

b s b  0 1 a s a   1

0

y

3

2

b 3

b 2

b 1

b z 0

(

)

b s 3

b s 2

b s b Z s ( ) 1 0

    

4

3

2

(

s

)

a s 3

a s 2

a s a Z s ( ) 1 0

 Y s ( )    U s ( ) 

a

a

3

2

a 1

a z 0

dz dt

3 d z 3 dt 4 d z 4 dt

2 d z 2 dt 3 d z 3 dt

dz dt 2 d z 2 dt

  u 

x

2

z

2

x 3 x

4

a x 0 1

x 3 x

z  z  z 

4

x  1 x  2 x  3

x  1  x      

x  1 x  2 x  3 u a x   3 4 b x 1 2

b x 0 1

a x 2 3 b x 2 3

a x 1 2 b x 3 4

       x   4   y 

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23

Ex. 2

3

2

3b

G s ( )

4

Signal – Flow Graph & Block Diagram Models (11) Y s ( ) U s ( )

s

b s 2 

b s 3 

b s b  1 0 a s a   1

 2 a s 2

 3 a s 3

0

2b

4X

1b

1

1 s

1/ s

1/ s

1/ s

0b

x

( )U s

2

( )Y s

3X

2X

1X

3a

2a

1a

x 3 x

4

0a

a x 0 1

phase variable canonical form

x  1 x  2 x  3 u a x   3 4 b x 1 2

b x 0 1

a x 2 3 b x 2 3

a x 1 2 b x 3 4

      x   4   y 

3b

2b

1b

4X

3X

2X

1X

( )Y s

( )U s

0b

1 s

1 s

1 s

1 s

( )

( )

3a

2a

( )

1a

( )

0a

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24

Ex. 2

3

2

3b

G s ( )

4

Signal – Flow Graph & Block Diagram Models (12) Y s ( ) U s ( )

s

b s 2 

b s 3 

b s b  1 0 a s a   1

 2 a s 2

 3 a s 3

0

2b

4X

1b

1

1 s

1/ s

1/ s

1/ s

0b

( )U s

( )Y s

1X

3X

2X

3a

2a

1a

0a

phase variable canonical form

3b

2b

1x

2X

1X

1

1/ s

1/ s

1/ s

1b

1

( )Y s

( )U s

1/ s

1

1

4X

3X

0b

4x

3x

2x

2a

1a

3a

0a

input feedforward canonical form

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25

Ex. 2

3

2

G s ( )

4

Signal – Flow Graph & Block Diagram Models (13) Y s ( ) U s ( )

s

b s 2 

b s 3 

b s b  1 0 a s a   1

 2 a s 2

 3 a s 3

0

x

 

3

 

2 x 3

2

x u t ( )  

x

 

b u 3 b u 2 b u 1

 

0

a x 3 1 a x 2 1 a x 1 1 a x 0 1

4 b u 0

x d dt

x 1

x   1  x    x   3  x   4   y

3b

2b

1x

2X

1X

1

1/ s

1/ s

1/ s

1b

1

( )Y s

( )U s

1/ s

1

1

4X

3X

0b

4x

3x

2x

2a

1a

3a

0a

y t ( )       x  a    a  2   a  1  a   1 0 0 0  1 0 0 0 1 0 0 0 1 0 0 0  b   3   b 2     b 1   b   0   0 ( ) u t          

input feedforward canonical form

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26

Ex. 2

3

2

G s ( )

4

Signal – Flow Graph & Block Diagram Models (14) Y s ( ) U s ( )

s

b s 2 

b s 3 

b s b  1 0 a s a   1

 2 a s 2

 3 a s 3

0

3b

2b

1x

2X

1X

1/ s

1

1/ s

1/ s

1b

1

( )Y s

( )U s

1/ s

1

1

4X

3X

0b

4x

3x

2x

2a

1a

3a

0a

3b

2b

1b

4x

3x

2x

1x

4X

3X

2X

1X

( )U s

( )Y s

0b

1 s

1 s

1 s

1 s

( )

( )

( )

( )

3a

2a

1a

0a

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27

Ex. 3

( )U s

( )Y s

G s ( )

s 3( s s (

s s

2) 4)

 

Signal – Flow Graph & Block Diagram Models (15) Y s ( ) 1)(  3)(  U s ( )

T s ( )  

( )

2

G 1 G 

3

3

s  2 s 6 

3

 1 

X1

X2

s

6

s

s 3 1 10 

9 

6 s s  2  s 21 

G

( )

H

2X

1X

1

G GH

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28

3 s 10  1  9 6 s  21 s  2 

Ex. 3

( )U s

( )Y s

2

1

3

G s ( )

s 3( s s (

s s

2) 4)

Signal – Flow Graph & Block Diagram Models (15) 1)(  3)( 

 

3

( )

3

9

1

1/ s

1/ s

1/ s

6

( )U s

( )Y s

1X

3X

2X

10

21

6

1

2

3

4

T s ( )

 1

4

 2 

 3 

1

b s 3 a s  3

b s 2 a s  2

b s 1 a s  1

b s 0 a s  0

3b

2b

4X

1b

1

1 s

1/ s

1/ s

1/ s

0b

( )U s

( )Y s

3X

2X

1X

3a

2a

1a

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29

0a

T s ( )   1  s 6 s s 3 1 10  9  6 s s  2  s 21 

Ex. 3

( )U s

( )Y s

2

3

1

G s ( )

s 3( s s (

s s

2) 4)

Signal – Flow Graph & Block Diagram Models (16) 1)(  3)( 

 

3

( )

3

9

1

1/ s

1/ s

1/ s

6

( )U s

( )Y s

1X

3X

2X

10

21

6

3

9

3X

2X

1X

( )Y s

( )U s

6

1 s

1 s

1 s

( )

10

21

( )

6

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30

T s ( )   1  s 6 s s 3 1 10  9  6 s s  2  s 21 

Ex. 3

( )U s

( )Y s

1

2

3

G s ( )

s 3( s s (

s s

2) 4)

Signal – Flow Graph & Block Diagram Models (17) 1)(  3)( 

 

3

( )

3

9

1

1/ s

1/ s

1/ s

6

( )U s

( )Y s

1X

3X

2X

10

21

6

0

1

0

x 1 x

0

0

1

x 1 x

u t ( )

x

2

d dt

6 21

10

2 x 3

2 x 3

    

    

    

         

    

0     0     1  

10

21

x

6

x  1 x  2 u  

x 1

2

x 1

y t ( )

x

6

9

x

3

x 3 

 6 9 3

2

x 1

x 3

   x  3  x   3   y 

2 x 3

    

    

           

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31

T s ( )   1  s 6 s s 3 1 10  9  6 s s  2  s 21 

Ex. 3

( )U s

( )Y s

3

2

1

G s ( )

s 3( s s (

s s

2) 4)

Signal – Flow Graph & Block Diagram Models (18) 1)(  3)( 

 

3

( )

3

9

1

1/ s

1/ s

1/ s

6

( )U s

( )Y s

1X

3X

2X

10

21

6

3

2X

1X

2x

1x

3X

1/ s

9

1/ s

1

1

( )Y s

( )U s

1/ s

1

6

3x

21

6

10

x

u 3

10

 

10 1 0

21 0 1

T s ( )   1  s 6 s s 3 1 10  9  6 s s  2  s 21 

x

u t ( )

9

u

21

 

2 x 3

2

x d dt

6

6

u 6

x 1 x 1 

 

x 1

y t ( )

     x 

        1 0 0 

0 0 

3     9     6     0 ( ) u t

x 1

x    1  x    x   3   y

       

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32

Ex. 3

( )U s

( )Y s

1

2

3

G s ( )

s 3( s s (

s s

2) 4)

Signal – Flow Graph & Block Diagram Models (19) 1)(  3)( 

 

3

( )

3

9

1

1/ s

1/ s

1/ s

6

( )U s

( )Y s

1X

3X

2X

10

21

6

3

2X

1X

2x

1x

3X

1/ s

9

1/ s

1

1

( )Y s

( )U s

1/ s

1

6

3x

21

6

10

3

9

3x

2x

1x

2X

1X

3X

( )U s

( )Y s

6

1 s

1 s

1 s

( )

( )

( )

10

21

6

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33

T s ( )   1  s 6 s s 3 1 10  9  6 s s  2  s 21 

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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34

Alternative Signal – Flow Graph & Block Diagram Models (1)

Ex. 1

Field voltage

Field current

Velocity

( )Y s

( )R s

5

( )U s

I s ( )

1 2s 

6 3s 

Motor & load

s 1  s 5  Controller

x

x 

6 2  0

0 20 5

    

0     5 ( ) r t     1  

x

     ( ) y t 

3  0 0  1 0 0

  

5

      

2X

1/ s

1X

1/ s

1

6

1

3X

( )Y s

( )R s

5

1/ s

( )U s

I s ( )

1

2

5

3

5

3X

1X

( )U s

I s ( )

( )R s

( )Y s

5

6

2X

1 s

1 s

1 s

( )( )

( )( )

( )( )

5

3

2

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35

Alternative Signal – Flow Graph & Block Diagram Models (2)

Ex. 1

Field voltage

Field current

Velocity

( )Y s

( )R s

5

( )U s

I s ( )

1 2s 

6 3s 

Motor & load

s 1  s 5  Controller

T s ( )     

1X

20

1/ s

1X

1 s

( )( )

1

5

20

( )

5

( )

2X

2X

1

( )R s

( )Y s

( )R s

( )Y s

10

10

1/ s

1 s

( )( )

30

1

2

2 1/ s

3X

Y s ( ) R s ( ) 30( s 5)( 1)  2)( s ( s 3) s    20  s 5  10  s 2  30 s 3 

Diagonal canonical form

3X

30

1 s

3

( )( )

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36

3

Alternative Signal – Flow Graph & Block Diagram Models (3)

Ex. 1

Field voltage

Field current

Velocity

( )Y s

( )R s

5

( )U s

I s ( )

1 2s 

6 3s 

5

r t ( )

 

Motor & load

s 1  s 5  Controller

x 1 x

r t ( )

2

 

2

2

r t ( )

3

 

x  1 x  x  3 ( ) y t

10

x

30

 

x 3 x 20 1

x 3

2

      

1X

20

0

5

0

1 s

( )( )

2

 0

x

0

x 

5

( )

 0

( )

2X

( )R s

( )Y s

10

20

    3  10 30

1 s

    0   ( ) y t  

1     1 ( ) r t     1    x

( )( )

       

2

3X

Diagonal canonical form

30

1 s

( )( )

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37

3

x

2 

x 1 

u t ( ) 1 u t ( ) 2

2

2

x 1

d dt

u t ( ) 1 u t ( ) 2

  

x

0 0 0

    

2

Ex. 2 x    1 x  x  3

x 1

x 1 x 2 x 3

x 1 x 2 x 3

Alternative Signal – Flow Graph & Block Diagram Models (4) 1 0    x   0 1    0 0  

       

         

    

    

    

    

( )

1U

1X

1 s

1X

1/ s

1

( )

1U



1/ s

3X



3X

1 s

1/ s

1

2U

2X

2X



2U

1 s

( )( )

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38

Ex. 3

m

u t

Alternative Signal – Flow Graph & Block Diagram Models (5) my  My ml  

( ) 0 



0

2  

mgl 

mly ml  

mg

l

(

,

,

)

,

)

 y y   ( , , 

x x x x , 1 2

3

4

( )u t

u t

( ) 0 

M

0

 2 

lx 

x 

Mx mlx   4 gx 3

2

4

   

( )y t

x

2

u t ( )

 

x 

2

x 3

mg M

1 M

u

x

d dt

x  3

x 1 x 2 x 3 x

x 1 x 2 x 3 x

0 1 0 0 0 0 0 0

0 mg M / 0 g l /

0 0 1 0

0 M 1/ 0 Ml 1/(

)

4

4

     

     

     

     

     

     

     

     

u t ( )

x 

4

x 3

4 g l

1 Ml

x   1         

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39

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State

Equation

6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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40

The Transfer Function from the State Equation (1)

x Ax B u   y Cx D u 

 

  

 CX

AX s ( ) s ( )

B U s ( )  D U s ( )

X s ( ) s    ( ) Y s 

)

s ( )

B

U s ( )

I A X s (  

1

X

s ( )

 I A B s ]

[

U s ( )

( ) s U s ( )  Φ B

Y s ( )

[

U s ] ( )

CΦ B D s ( )

G s ( )

CΦ B D s ( )

Y s ( ) U s ( )

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41

L

Li C

R

0

 ov 

( )u t

x u u Ax B     x   Cv 

Ci

1 C 0        

R y 

The Transfer Function from the State Equation (2) 1    C  R    L   x Cx 

   1   L   0

Ex.        

0

s

[

]

I A s 

s 0

0 s

  

  

s

1 L

1  C R  L

1  L

     

     

     

1   C  R   L 

s s  

1

 ]

2

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42

R L 1  C R L 1  C             s ( ) [ s     Φ  I A 1 s ( )  s s   s s 1 R L 1 LC 1 L 1 L                        

L

Li C

R

0

 ov 

( )u t

x u u Ax B     x   Cv 

Ci

1 C 0        

R y 

The Transfer Function from the State Equation (3) 1    C  R    L   x Cx 

   1   L   0

Ex.        

G s ( )

0

R

1 C 0

   

1  C s ( )  s s ( )

R L s ( ) 1 L s ( ) 

 s       

          

R L 1  C  s      s ( )  Φ 1 s ( ) 

s

)

2

s

s

G s ( )

1 L            

CΦ B D ( ) s

R LC /( R L

1 LC

Y s ( ) U s ( )

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43

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using Control

Design Software

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44

The Time Response & the State Transition Matrix (1)

t

x

t ( )

exp(

A x t

) (0)

exp[

A

(

t

)

Bu

r d ( ) 

0

t

t

)

( ) 

d 

t ( ) (0) Φ x

( Φ

Bu

0

Φ(t): the state transition matrix

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45

L

The Time Response & the State Transition Matrix (2) Li C

R

0

 ov 

( )u t

u u x  Ax B    x   Cv 

Ci

1 C 0        

y R     1   L   0 1    C  R    L   x Cx 

Ex.        

0 2 

 1 0

R 3, L 1, C 0.5 A , B , C       

s

s

3

 3

1

s ( )

[

 ]

1 3        2     0  

Φ

s  I A

2

1 s ( )

 1

2  s

 1

2  s

1 s 3

s

  2  

  

  

  

t

2

t

t

2

t

(2

e

e

)

e

2

e

)

( 2 

t ( )

Φ

t

2

t

t

2

t

(

e

e

)

(

e

2

e

)

    

   

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46

L

The Time Response & the State Transition Matrix (3) Li C

R

0

 ov 

( )u t

u u x  Ax B    x   Cv 

Ci

1 C 0        

R y  1    C  R    L   x Cx     1   L   0

Ex.        

t

2

t

t

2

t

(2

e

e

)

e

2

e

)

( 2 

t ( )

Φ

t

2

t

t

2

t

(

e

e

)

(

e

2

e

)

    

   

t

x

t ( )

t

)

( ) 

d 

t ( ) (0) Φ x

( Φ

Bu

0

2

t

e

(0)

x

u t

( ) 0

t ( )

(0) 1, 

 

Φ

x 1

2

2

t

x t ( ) 1 x t ( ) 2

e

1     1  

  

  

    

   

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47

Ex.

L

2

t

e

The Time Response & the State Transition Matrix (3) Li C

R

t ( )

Φ

2

t

x t ( ) 1 x t ( ) 2

e

1     1  

  

  

 ov 

    

   

( )u t

Ci

1

1

1

0.9

0.9

0.9

0.8

0.8

0.8

0.7

0.7

0.7

0.6

0.6

0.6

) t (

) t (

) t (

1

1

2

0.5

0.5

0.5

x

x

x

0.4

0.4

0.4

0.3

0.3

0.3

0.2

0.2

0.2

0.1

0.1

0.1

0

0

0

0

0.5

1.5

2

0

0.5

1.5

2

0.2

0.4

0.6

0.8

1

0

1 t

1 t

x1(t)

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48

 Cv 

State Variable Models

1. The State Variables of a Dynamic System 2. The State Differential Equation 3. Signal – Flow Graph & Block Diagram Models 4. Alternative Signal – Flow Graph & Block

Diagram Models

5. The Transfer Function from the State Equation 6. The Time Response & the State Transition

Matrix

7. Analysis of State Variable Models Using

Control Design Software

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49

Analysis of State Variable Models Using Control Design Software

Ex.

2

T s ( )

3

Y s ( ) R s ( )

 2 s

s

6

s 3 10 

s 6 9  21 s 

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