PID Control 3P T1T2T3 Step Response and Bode Plot

Cuthbert Nyack
Applet shows the frequency response(Bode plot) of a third order type 0 system with PID control.

The PID controller magnitude and phase is shown in brown and light magenta. Comparing P control magnitude(Yellow) with PID controlled magnitude(Red) shows an increase at low frequencies(I controller) and at high frequencies(D controller). The phase comparison shows an increase in phase lag at low frequencies(I control) and a reduction at high frequencies(D control). With parameters (8.0, 1.0, 1.0, 1.0, 1.0, 1.1, 0.3) both the P and PID controlled systems are unstable. Bode plot shows that with these parameters the PID controller has had negligible effect on the phase and gain margins. Increasing Ti,Td increases the phase margin +vely while reducing them increases the phase margin -vely.

Gif image below show how the applet should appear.

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COPYRIGHT 2006 Cuthbert Nyack.