Code only - step disturbance at 40 seconds

Hi All,

Can anyone help me with pure code for a step disturbace at 40 seconds? I dont want to use symulink for this project and i am interested in the fundamentals.

I need to test the tuning by applying a step disturbance at 40 seconds to see how the controller responds in each case.

Help very much appreiciated!!

Question:

what is the code to implement a step disturbance in the system at 40 seconds that would test the disturbance rejection of the controller and allow the system to return to 1?

Disturbance is defined as G_Disturbance in the below code.

matlab version R2018b

load time.dat

load response.dat

plot (time,response,'g');

title ('Actual response')

xlabel ('Time')

ylabel ('Amplitude')

hold on

s=tf('s')

K = 2;

tau = 3;

sysmod = exp(-s)*(K/(tau*s+1))

plot (time,response,'g');

hold on

step (sysmod,'k')

title ('System Model Step Response')

hold off

Applying the Hagglund-Astrom Tuning

theta = 0.1; % Defines the dead time in the process

kp = (0.14/K)+((0.28*tau)/(theta*K)) % Defines the Proportional element CORRECT

ki = ((0.33*theta) + ((6.8*theta*tau)/(10*theta+tau))) % Defines the Integral element CORRECT

G_disturbance = (exp(-40*s)*(1)) % Function for the disturbance

%haggast1 = feedback ((kp + (ki/s)) * sysmod,1); % Applying the Hagglund-Astrom tuning

haggast1 = feedback ((K*(1+(ki/kp)/s)) * sysmod,1);

step (haggast1,'g')

hold on

step (sysmod,'k')

title ('Haggland-Astrom Tuning')

%step (G_disturbance + haggast1,'r',60) % Applying Disturbance

legend ('haggast1','sysmod','disturbance')

hold off

Applying the Cohen and coon PI Tuning

theta1 = 0.1;

kp1 = (1/K)*(tau/theta1)*(0.9+(theta1/(12*tau))) % Defines the Proportional element CORRECT

ki1 = (theta1*(30+(3*(theta1/tau))) / (9+(20*(theta1/tau)))) % Defines the Integral element CORRECT

%CC = feedback ((kp1 + ki1/s) * sysmod,1); % Applying the Cohen Coon tuning

CC = feedback ((K*(1+(ki1/kp1)/s)) * sysmod,1);

step (CC,'g',100)

hold on

step (sysmod,'k')

title ('Cohen Coon Tuning')

legend ('CC','sysmod')

hold off

Ziegler-Nichols Reaction curve PID settings

RN = 13;

L = 0.1;

Kp_P = 1/(RN*L);

Kp_PI = 0.9/(RN*L);

Kp_PID = 1.2/(RN*L);

Ki_PI = 3*L;

Ki_PID = 2*L;

Kd_PID = 0.5*L;

ZN_P = feedback ((Kp_P)*sysmod,1);

ZN_PI = feedback ((Kp_PI + Ki_PI/s) * sysmod,1);

ZN_PID = feedback ((Kp_PID + Ki_PID/s + s*Kd_PID) * sysmod,1);

step (ZN_PID,'b')

hold on

step (ZN_PI,'y')

step (ZN_P,'g')

title ('Ziegler Nichols')

legend ('PID','PI','P')

hold off

[Image Analyst]

Probably but you forgot to ask a specific question and forgot to attach your data files.

https://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Toby Russell]

Good Morning,

Thank you for your reply.

OK, sorry for the lacking info.

the data files are attached, not possible to load .dat here so they are in excel format.

below is a copy of latest code, I am running a live script for this.

Question:

1. is it possible to code a step disturbance to occur at 40 seconds that would test the conntrollers disturbance rejection and allow the controler to return the output to 1?
2. how would this be achieved in code?

MATLAB version - R2018b

I will edit the code in my origninal question to show the lastest verion of where I am. Iam using G_Disturbance to define the disturbance.

best regards

Toby