feedback function

Feedback Connection of LTI systems

feedback forms a feedback connection for two LTI state-space or transfer function systems

feedback(sys1, sys2, in1, out1)

Arguments

• sys1: LTI system model of transfer-function or state-space model
• sys2: LTI system model of transfer-function or state-space model
• in1: vector of inputs
• out1: vector of outputs

Returns

Returns the feedback system in tf or ss model

Details

When sys1 and sys2 are transfer functions feedback(sys1, sys2, SIGN) produces the SISO closed loop system in transfer function form obtained by connecting the two SISO transfer function systems in feedback with the sign SIGN.

feedback(sys1, sys2, SIGN) produces an aggregate state-space system consisting of the feedback connection of the two systems 1 and 2. If SIGN = 1 then positive feedback is used. If SIGN = -1 then negative feedback is used. In all cases, the resulting system has the same inputs and outputs as system 1.

feedback(sys1, sys2, inputs, outputs)

produces the feedback system formed by feeding all the outputs of system2 into the inputs of system 1 specified by INPUTS1 and by feeding the outputs of system 2 specified by OUTPUTS1 into all the inputs of system 2. Positive feedback is assumed. To connect with negative feedback, use negative values in the vector INPUTS1.

feedback() calls fdbcksys() to perform the feedback connection for two systems. Unity feedback calls are possile, for example, feedback(sys1, 1), feedback(1, sys1)

Examples

C <- pid(350,300,50)
P <- TF(" 1/(s^2 + 10* s + 20)")
feedback(C,P)
feedback(P,P,1)
feedback(P,P,-1)
feedback(P,P)
feedback(P,1)
feedback(TF("C*P"))
## Not run:  On Octave: feedback(C*P)

See Also

cloop parallel series