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

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

[Guillaume]

What does

which pid

return?

[Phyo]

pid should return double too. just like tf or feedback function I guess. but the error encountered was

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

Error in ==> Untitled4 at 17 Gc = pid(Kp,Ki,Kd);

[Phyo]

though I put all value as int, the error shows the same thing.

[Guillaume]

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]

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

Answer 1

[Arkadiy Turevskiy]

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.