PD Control 2P 0T1, T1T2 Step Response and Root Locus

Cuthbert Nyack

Applet shows the root locus (closed and open loop poles) of a system with a PD controller and its connection to the transient and frequency response.

One example of P control is the parameter values (K, 1.0, 5.0, 0.0, 1.0). For K < ~0.8 the roots are real and become complex conjugate for larger K. As K increases, the poles move parallel to the imaginary axis and the overshoot and oscillatory behaviour increases.
One example of PD control is the parameter values (K, 1.0, 5.0, 0.4, 1.0). In this case the poles move on a circle instead of a vertical line and the overshoot and oscillatory behaviour is reduced.

Gif image below show how the applet should appear.

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