Reputation: 1
I have to design a fractional order PID controller using the IMC method for my project and I need to find an approximation for (s − ψ) ^α,something similar to:
>THE FOLLOWING LINES ARE FROM THE ATTACHED IMAGE
s^α ∼= e^α(s−1)
(s − ψ)^α ∼= e^(α(s−1)−αψ)
(s − ψ)^α ∼= (s^α)\*(e^−αψ)
Can anyone give me a different approximation
\[IMC method for fractional order PID\](https://i.sstatic.net/wDUpQ.png)
We tried looking into Chebyshev approximation and we couldn't find anything. We just need a different approximation and the rest of the method would be the same as in the attached image.
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