How can I convert a transfer function into time dependent using ilaplace

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Tejas 2013-10-17

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评论： lithika 2014-2-28

I have tried to use ilaplace

X2=(F*G3+C*G3)/(1+C*G3); % F,G3,C are transfer functions generated using tf

v=sym('X2');

x=ilaplace(v);

then i use it to plot a function using plot but when i try to run the code i get an error as shown below

??? The following error occurred converting from sym to double: Error using ==> mupadmex Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.

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Answer 1

Jonathan LeSage 2013-10-17

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在 MATLAB Online 中打开

The ilaplace function works on symbolic expressions and not transfer function models. You need to convert the transfer function, X2, into a symbolic expression prior to using the ilaplace function.

Here are some links to some relevant functions:

To get you started, here is some example code of one potential method of conversion:

% Your transfer function model
X2 = (F*G3+C*G3)/(1+C*G3);
% Extract the numerator/denominator
[num,den] = tfdata(X2);
% Build symbolic expression using the numerator/denominator
syms s
arrayNum = cell2mat(num);
arrayDen = cell2mat(den);
X2_symbolic = poly2sym(arrayNum,s)/poly2sym(arrayDen,s);
% Valid usage of ilaplace on a symbolic
x = ilaplace(X2_symbolic);