Laplace.T	Root-locus	Transient response	Frecuency response

3 Program 6.3 OGATA 4edition (root locus)

Let us calculate the root-locus of a closed-loop system with feedback by Scilab, whose transfer function in open loop is:

$\begin{displaymath}G(s)=\frac{K}{(s^{4}+1.1\cdot s^{3}+10.3\cdot s^{2}+5\cdot s)}\end{displaymath}$

Program in Scilab

clf;
num=poly([1 0 0 0 0],'s','coeff');
den=poly([0 5 10.3 1.1 1],'s','coeff');
g=syslin('c',num/den);
for k1=0.2:0.2:20,
  gl=1+k1*g;
  numl=numer(gl);
  r=roots(numl);
  x=real(r);
  y=imag(r);
  plot(x,y,'o');
end;
for k2=20.02:0.2:30,
  g2=1+k2*g;
  num2=numer(g2);
  r2=roots(num2);
  x2=real(r2);
  y2=imag(r2);
  plot(x2,y2,'o');
end;
for k3=35:5:1000,
  g3=1+k3*g;
  num3=numer(g3);
  r3=roots(num3);
  x3=real(r3);
  y3=imag(r3);
  plot(x3,y3,'o');
end;
v=[-20 20 -25 25];
mtlb_axis(v)
xgrid;

Image Programa6_3