www.gusucode.com > control 案例程序 matlab源码代码 > control/SecondOrderTransferFunctionFromDampingAndFrequencyExample.m

    %% Second-Order Transfer Function from Damping and Natural Frequency
% Create a |tf| model that represents a second-order system with
% known natural frequency and damping ratio. 
%%
% The transfer function of a second-order system, expressed in terms of its
% damping ratio $\zeta$ and natural frequency $\omega_0$, is:
%%
% 
% $$H\left( s \right) = \frac{{\omega _0^2}}{{{s^2} + 2\zeta {\omega _0}s + \omega _0^2}}.$$
% 
%%
% Represent this transfer function in MATLAB using the |tf| command.  For
% example, suppose you have a system with $\zeta$ = 0.25 and $\omega_0$ = 3
% rad/s.

% Copyright 2015 The MathWorks, Inc.

zeta = 0.25;
w0 = 3;
H = tf(w0^2,[1,2*zeta*w0,w0^2])
%%
% Examine the response of this transfer function to a step input.
stepplot(H)
%%
% The plot shows the ringdown expected of a second-order system with a low
% damping ratio.