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how can i solve this problem

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syms z kd kp ki a b c;
gs=tf([1369 74],[369600 51080 400 0])
gz=c2d(gs,3,'zoh')
gzz=(0.0004566*z^2+5.817e-06*z-0.0004382)/(z^3-2.933*z^2+2.866*z-0.9332);
f=(kp*(z-kd)*(z-ki))/(z*(z-1));
tzz=gzz*f/(1+gzz*f);
[n,d]=numden(tzz);
d=coeffs(d,z,'all');
d=d/d(1);
pd=(z^2+0.69*z+0.754)*(z^3+a*z^2+b*z+c)
pd=coeffs(pd,z,'all');
prob=pd==d;
sol=solve(prob,[kd ki a b c])
kiv=sol.ki(1);
kdv=sol.kd(1);
av=sol.a(1);
bv=sol.b(1);
cv=sol.c(1);
kpval=0:0.1:600
table=zeros(length(kpval));
for i=1:length(kpval)
table(i,1)=kpval(i);
table(i,2)=double(subs(kiv,kp,kpval(i)));
table(i,3)=double(subs(kdv,kp,kpval(i)));
table(i,4)=double(subs(av,kp,kpval(i)));
table(i,5)=double(subs(bv,kp,kpval(i)));
table(i,6)=double(subs(cv,kp,kpval(i)));
Dz=tf([table(i,1) -table(i,1)*(table(i,3)+table(i,2)) table(i,1)*table(i,2)*table(i,3)],[1 -1 0],3)
Tz=feedback(Dz*Gz,1)
info=stepinfo(Tz)
tablo(i,7)=info.Overshoot;
tablo(i,8)=info.SettlingTime;
end
%%%
Error using symengine
Division by zero.
Error in sym/subs>mupadsubs (line 160)
G = mupadmex('symobj::fullsubs',F.s,X2,Y2);
Error in sym/subs (line 145)
G = mupadsubs(F,X,Y);
Error in Untitled7 (line 23)
table(i,2)=double(subs(kiv,kp,kpval(i)));

  2 Comments

KSSV
KSSV on 27 May 2020
Copy paste the code here.....not an image snippet.
madhan ravi
madhan ravi on 28 May 2020
Don’t use table as a variable name.

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Accepted Answer

Ameer Hamza
Ameer Hamza on 28 May 2020
In the expressions of kiv and kdv, there is kp in the denominator. So, you should start the list of Kp from a non-zero value, for example, change the line to
kpval=0.1:0.1:600 % start from 0.1
also, there appear to be another issue on the line
Tz=feedback(Dz*Gz,1)
Gz is not defined in your code. I guess it should be 'gz'.

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