tf2ss not returning the correct State Space form

Question

Christopher Delmond 2020-11-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/666883-tf2ss-not-returning-the-correct-state-space-form

回答： Star Strider 2020-11-28

采纳的回答： Star Strider

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I want to obtain the state space form of the following transfer function using tf2ss:

I went ahead and obtained the state space represention by hand:

So the code I developed to get the state space matrices for the transfer function was:

NUM = [1];
DEN = [1 -1 10];
[A,B,C,D] = tf2ss(NUM,DEN);

The state space matrices returned were:

A = [1 -10 ; 1 0]
B = [1 ; 0]
C = [0 1]
D = 0

It seems to have computed the correct numbers, but they are in the incorrect locations. How do I ensure that tf2ss returns the correct state space matrix representation?

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Answer 1

Star Strider 2020-11-28

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/666883-tf2ss-not-returning-the-correct-state-space-form#answer_558688

The result is correct. The exact configuration doesn’t matter, so long as all the matrices and vectors work together (and produce the correct result).

It may be possible to create a transformation matrix of some sort, however it’s likely not worth the effort. (For what it’s worth, the Control System Toolbox produces a result analogous to the Signal Processing Toolbox that you are using here, except for normalising it.)