Bode, Nyquist, and Nichols Diagrams of Second-Order Systems
Consider a second-order system given by the transfer function:[more]
where is the damping coefficient, is the response time, and is the process steady-state gain.
This Demonstration plots the Bode, Nyquist, and Nichols diagrams for user-set values of the parameters , , and . Different behaviors are observed for (underdamped or oscillating system), (critically damped system), and (overdamped system).[less]
 D. E. Seborg, T. F. Edgar, D. A. Mellichamp, and F. J. Doyle III, Process Dynamics and Control, 3rd ed., New York: John Wiley & Sons, 2010.