Pole placement design, Control Theory

AI Thread Summary
The discussion revolves around a query regarding pole placement in control theory, specifically focusing on the characteristic equation derived from a closed-loop transfer function. The user presents their calculations for the open-loop transfer function and the closed-loop transfer function, ultimately leading to a characteristic equation. They express confusion over the roots of the equation, noting that their expected result, s = -β ± iβ, does not hold true. The user later mentions finding a solution on a math forum, indicating that the issue has been resolved. The conversation highlights the complexities involved in pole placement design within control systems.
rakso
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Summary:: Control Theory root equation pole

Hi, I ran into a simple question but somehow I can't get it right.
Skärmavbild 2020-11-02 kl. 14.28.47.png

My work this far:

## G_0(s) = G(s) \cdot K \cdot \frac{1}{T_I s} = \frac{k}{\tau s +1} \cdot \frac{2\beta \tau -1}{k} \cdot \frac{2\beta^2 \tau}{Kks} = \frac{2\beta^2\tau}{s(\tau s +1)},##

## G_{cl}(s) = \frac{G_0}{1+G_0} = \frac{2\beta^2 \tau}{s(\tau s +1)+2\beta^2 \tau}.##

Hence the characteristic equation for the poles is ## \phi(s) = s(\tau s +1)+2\beta^2 \tau##, but ## s = -\beta \pm i \beta ## is not a root.

Does anyone see my error?

Muchos gracias
 
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