showing "too many output arguments" error in this code

function [J] = pid_optim(x)

s = tf('s');

plant = 1 / (s^2 + 10*s + 20);

Kp = x(1);
Ki = x(2);
Kd = x(3);

cont = Kp + Ki/s + Kd * s;

step(feedback(plant*cont,1));

dt = 0.01;
t = 0:dt:1;

e = 1 - step(feedback(plant*cont,1),t);

J = sum(t'.*abs(e)*dt);

Answer 1

[ag]

Hi Keerthana,

I understand that you are getting “too many output arguments” error while implementing genetic algorithm.

I tried to run the function provided by you, and it ran without any errors. Try to modify the caller function to rectify the error.

Below is the full working code:

s  = tf('s'); 
Gp = 1 / (s^2 + 10*s + 20); 

step(Gp, 2), grid on 
nvars     = 3; 
K = ga(@pid_optim, nvars) 
Gc = K(1) + K(2)/s + K(3)*s;  % ideal type 
Gcl = feedback(Gc*Gp, 1); 
step(Gcl, 2), grid on 
S = stepinfo(Gcl) 

function [J] = pid_optim(x) 
    s = tf('s'); 
    plant = 1 / (s^2 + 10*s + 20); 
    Kp = x(1); 
    Ki = x(2); 
    Kd = x(3); 
    cont = Kp + Ki/s + Kd * s; 
    %step(feedback(plant*cont,1)); 
    dt = 0.01; 
    t = 0:dt:1; 
    e = 1 - step(feedback(plant*cont,1),t); 
    J = sum(t'.*abs(e)*dt); 
end 

Please refer to the below resources for more details:

• https://www.mathworks.com/matlabcentral/answers/640585-ga-algorithm-for-pid-tuning?s_tid=answers_rc1-3_p3_Topic
• https://www.mathworks.com/help/gads/genetic-algorithm-options.html

Hope this helps!

Best Regards,

Aryan Gupta