National Instruments 370753C-01 Manual De Usuario

2

C

-1.5 1.5

D

0

X0

0

0

For the feedback system shown in Example 3-3, you can write the 
following system equations:

Combining these equations with the equation for the positive feedback 
input term:

and multiplying by the input and output gains M and N, you obtain the 
following state-space equations describing the entire system between input 
u and output y. If you do not specify any values for the gain matrices, 
K defaults to zero (no feedback) and M and N default to appropriately-sized 
identity matrices (unity gain on the input and output).

This algorithm assumes that the closed-loop system is well posed to ensure 
that 

Sys

 will be proper. The (I – KD

1

) term must be invertible, and a 

warning appears if the condition estimate of the term (refer to 

rcond

) is 

less than 

eps

. 

x·

1

1

1

+

=

1

1

1

1

+

=

1

1

+

=

x·

1

1

1

–

(

)

1

–

1

+

(

)x B

1

1

–

(

)

1

–

+

=

1

–

(

)

1

–

1

1

1

–

(

)

1

–

+

=