Laplace from symbolic to tf tooling.

Question

am 2021-2-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/732423-laplace-from-symbolic-to-tf-tooling

评论： am 2021-2-1

Hello, I want to use the function stepinfo().

I understood from different posts that "Control System Toolbox objects and Symbolic Math Toolbox objects are inherently incompatible" (@Star Strider). But in all the responses I saw in the forum, the transfer function was already available.

How do I get the the transfer function from a non laplacian function?

The faulty code:

syms t
k = 3
T2 = 10
c = 2
time_vector = [1:1:50];
y =@(t) k*(1.-exp(-t/T2))*c
laplace(y)
results = y(time_vector);
laplace(y)

Error: Check for missing argument or incorrect argument data type in call to function 'laplace'.

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Answer 1

Walter Roberson 2021-2-1

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/732423-laplace-from-symbolic-to-tf-tooling#answer_611313

在 MATLAB Online 中打开

syms s t

k = 3

T2 = 10

c = 2

time_vector = [1:1:50];

y = @(t) k*(1.-exp(-t/T2))*c

y = function_handle with value:

@(t)k*(1. -exp(-t/T2))*c

Y = laplace(y(t), t, s)

Y =

[n, d] = numden(Y)

n =

6

d =

yTF = tf(sym2poly(n), sym2poly(d))

yTF = 6 ---------- 10 s^2 + s Continuous-time transfer function.

step(yTF, time_vector)

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am 2021-2-1

编辑：am 2021-2-1

在 MATLAB Online 中打开

Thank you, I missed you just needed to install it.

I want to see the stepinfo(), the raise time, settling time etc.

Now I do not have errors, I do have a plot but no step responses. How can I visualise the stepinfo()?

syms s t
k = 3
T2 = 10
c = 2
time_vector = [1:1:50];
y = @(t) k*(1.-exp(-t/T2))*c
results = y(time_vector);
plot(time_vector,results)
hold on
grid on
xlabel('Time')
ylabel('Temperature')
Y = laplace(y(t),t, s)
[n,d] = numden(Y)
yTF = tf(sym2poly(n), sym2poly(d))
stepinfo(yTF)