Function 'subindex' is not defined for values of class 'ss' of 'zpk'
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Dear All
I am following MATLAB tutorial in Mathworks "Designing PID for Disturbance Rejection with PID Tuner" While following this tutorial, I got the following error in the picture. and another error is
"Function 'subsindex' is not defined for values of class 'zpk'."
The errors occurred after the following commands
G = zpk(-5,[-1 -2 -3 -4],6,'OutputDelay',1);
G.InputName = 'u';
G.OutputName = 'y';
C = pid(0.64362,0.30314);
C.InputName = 'e';
C.OutputName = 'u';
b = 0.7;
% The following code constructs an ISA-PID from F and C
F = tf([b*C.Kp C.Ki],[C.Kp C.Ki]);
F.InputName = 'r';
F.OutputName = 'uf';
Sum = sumblk('e','uf','y','+-');
ISAPID = connect(C,F,Sum,{'r','y'},'u');
tf(ISAPID)
% Closed-loop system with PI controller for reference tracking
sys1 = feedback(G*C,1);
% Closed-loop system with ISA-PID controller
sys2 = connect(ISAPID,G,{'r','u'},'y');
% Compare responses
step(sys1,'r-',sys2(1),'b.');
legend('show','location','southeast')
title('Reference Tracking')
The link of the tutorial is : https://www.mathworks.com/help/control/examples/designing-pid-for-disturbance-rejection-with-pid-tuner.html
Can anyone guide me how to remove these errors ?
Thank you
0 Comments
Accepted Answer
Steven Lord
on 26 Oct 2017
If you run these lines of code one by one, on which line does the error occur?
My suspicion is that you have created a variable named connect if the error occurs on the line of code where you're trying to call the connect function.
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