Function File: sys = feedback (sys1)

Function File: sys = feedback (sys1, "+")

Function File: sys = feedback (sys1, sys2)

Function File: sys = feedback (sys1, sys2, "+")

Function File: sys = feedback (sys1, sys2, feedin, feedout)

Function File: sys = feedback (sys1, sys2, feedin, feedout, "+")

Feedback connection of two LTI models.

Inputs

sys1

LTI model of forward transmission. [p1, m1] = size (sys1).

sys2

LTI model of backward transmission. If not specified, an identity matrix of appropriate size is taken.

feedin

Vector containing indices of inputs to sys1 which are involved in the feedback loop. The number of feedin indices and outputs of sys2 must be equal. If not specified, 1:m1 is taken.

feedout

Vector containing indices of outputs from sys1 which are to be connected to sys2. The number of feedout indices and inputs of sys2 must be equal. If not specified, 1:p1 is taken.

"+"

Positive feedback sign. If not specified, "-" for a negative feedback interconnection is assumed. +1 and -1 are possible as well, but only from the third argument onward due to ambiguity.

Outputs

sys

Resulting LTI model.

Block Diagram

 u    +         +--------+             y
------>(+)----->| sys1  |-------+------->
        ^ -     +--------+       |
        |                       |
        |      +--------+       |
        +-------| sys2  |<------+
                +--------+

Package: control