Undefined function or method 'pid' for input arguments of type 'double'.

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Phyo 2014-11-24

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https://ww2.mathworks.cn/matlabcentral/answers/164008-undefined-function-or-method-pid-for-input-arguments-of-type-double

回答： Arkadiy Turevskiy 2014-11-26

Hi, I am a beginner and would like to try out matlab for my assignment. I am encountering the error as ' Undefined function or method 'pid' for input arguments of type 'double'.' I can't figure out why. Please help.

clear all
clc
syms s
Gnum =exp(-0.5);
Gden = [7.724 32.317 25.220];  %((s+1)*((s+5)^2));
G=tf(Gnum,Gden);
H = 1;
T = feedback (G,H);
step(T)
hold on
Kp = 26.995;
Ki = 21.067;
Kd = 6.452; 
Gc = pid(Kp,Ki,Kd);
Mc = feedback(Gc*G,H);
step = (Mc);
grid on

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Guillaume 2014-11-24

在 MATLAB Online 中打开

I'll ask again, what does

which pid

return when you type that at the matlab prompt? That will tell us whether the function is visible to matlab or not.

Phyo 2014-11-24

you r right. pid function is not visible. I am using 2009a currently and trying to upgrade to newer version which includes that function.

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回答（1 个）

Arkadiy Turevskiy 2014-11-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/164008-undefined-function-or-method-pid-for-input-arguments-of-type-double#answer_160348

As you might have already realized, the pid objects were introduced in Control System Toolbox in release 2010b, so you would not be able to use them in 2009a.