stability test for complex valued transfer function

Question

Ömer Faruk Arslan 2022-1-25

回答： Mahesh Taparia 2022-3-3

Hello,

How can we test the stability of a "complex coefficient" transfer function? Assume that we have a plant ;

G = (5 +5j)/(s^2+4*s+4)

I see bode() function is able to that, however I m not sure about accuracy & correctness.

Thanks.

Answer 1

Mahesh Taparia 2022-3-3

Hi

You can use the 'isstable' function to check the stability of a transfer function. For example, in your case, consider the below code:

a=tf([5+5i],[1 4 4]);
Warning: The numerator or denominator of this transfer function has complex-valued coefficients.
isstable(a)
ans = logical
   1

For more information, you can refer this documentation. Hope it will help!