Question

我正在比较连续（s域）传递函数与其等效离散（z域）函数的时间响应。我使用c2d函数通过所有5种方法（Tustin，ZOH，FOH，冲量不变，匹配）离散化TF。阶跃响应函数对于所有传递函数（都是连续的离散函数）都可以正常工作，但是当我要进行斜率响应时，MATLAB没有斜率（）函数。我在网上发现的一个简单技巧是使用step（）并将TF除以s，它应该模拟斜坡响应step（G / s）。这对于连续TF来说效果很好，但对于其余离散TF却给出了错误

使用/时出错（第65行）采样时间必须一致。

如何解决此错误？

这是我的代码，第58行（最后一行）出现问题

clc
clear all
close all

s=tf('s') %Defining s as laplace domain vairable
Ts=0.1 %Sample Time

%Continuous Transfer Function
G = (-40824*s^2 - 122472*s + 1.497*10^8)/(s^4 + 186*s^3 + 4.67*10^4*s^2 + 3.71*10^6*s + 1.452*10^8)

%Continuous to Discrete conversion
Gt = c2d(G,Ts, 'tustin')
Gi = c2d(G, Ts, 'impulse')
Gz = c2d(G, Ts, 'zoh')
Gf = c2d(G, Ts, 'foh')
Gm = c2d(G,Ts,'matched')

%Bode Plot (Frequency Response) for all methods
bode(G,Gt,Gi,Gz,Gf,Gm)
legend('Continuous','Tustin (Bilinear)','Impulse Invariant','Zero-Order Hold','First-Order Hold','Matched')

%Step (Time Response) for all methods
figure; step(G,Gt,Gi,Gz,Gf,Gm)
legend('Continuous','Tustin (Bilinear)','Impulse Invariant','Zero-Order Hold','First-Order Hold','Matched')

%Impulse (Time Response) for all methods
figure; impulse(G,Gt,Gi,Gz,Gf,Gm)
legend('Continuous','Tustin (Bilinear)','Impulse Invariant','Zero-Order Hold','First-Order Hold','Matched')

%Root-Locus for continuous TF
figure; rlocus(G)
legend('Continuous')

%Root-Locus for Tustin method TF
figure; rlocus(Gt)
legend('Tustin (Bilinear)')

%Root-Locus for Impulse Invariant method TF
figure; rlocus(Gi)
legend('Impulse Invariant')

%Root-Locus for Zero-Order Hold method TF
figure; rlocus(Gz)
legend('Zero-Order Hold')

%Root-Locus for First-Order Hold method TF
figure; rlocus(Gf)
legend('First-Order Hold')

%Root-Locus for Matched method TF
figure; rlocus(Gm)
legend('Matched')

%Ramp Response for continuous TF
step(G/s)

%Ramp Response for Tustin method TF
step(Gt/s)

Answer 1

对于斜坡响应，您可以使用以下方法：

t=0:0.1:10;
r=t; %this is your input -u
Ts=0.1 ;
lsim(G,r,t);
figure
Gt = c2d(G,Ts, 'tustin');
lsim(Gt,r)

其中G是连续TF。

如何绘制离散（z域）传递函数的斜坡响应？ [MATLAB]

1 个答案: