//www.basicairdata.eu 2013 (c) JLJ
//Second order system step response plot and bode plot
//Example figure
s=poly(0,'s');
t=linspace(0,2,200);
//Second order transfer function Natural frequency wn 10 1/s, damping psi 0.15
//Denominator is in the form S^2+2*psi*wn*S+wn^2
//Numerator is wn^2 to have unity dc gain
//Natural frequency 10 1/s, damping 0.15
H1=(100)/(s^2+2*0.15*10*s+100);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,1);
xgrid();
//Natural frequency 10 1/s, damping 0.2
H1=(100)/(s^2+2*0.2*10*s+100);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,2);
//Natural frequency 10 1/s, damping 0.4
H1=(100)/(s^2+2*0.4*10*s+100);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,3);
//Natural frequency 10 1/s, damping 0.8
H1=(100)/(s^2+2*0.8*10*s+100);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,4);
xlabel("Time [s]")
ylabel("Step response")
xtitle("Second order system response to a unity step at t=0 s www.basicairdata.eu JLJ")
f1=figure();
f1.background=8;
//Now some wn value
//Natural frequency 10 1/s, damping 0.8
H1=(100)/(s^2+2*0.8*10*s+100);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,1);
xgrid();
//Natural frequency 20 1/s, damping 0.8
H1=(400)/(s^2+2*0.8*20*s+400);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,2);
//Natural frequency 100 1/s, damping 0.8
H1=(10000)/(s^2+2*0.8*100*s+10000);
fdt=syslin('c',H1)
y=csim('step',t,fdt);
plot2d(t,y,3);
xlabel("Time [s]")
ylabel("Step response")
xtitle("Second order system response to a unity step at t=0 s www.basicairdata.eu JLJ")