clear all;
close all;
Jp=0.0030;bp=0.067;
Jn=0.0033;bn=0.0673;
Gp=tf([1],[Jp,bp,0]);  %Practical plant
Gn=tf([1],[Jn,bn,0]);  %Nominal plant

tol=0.001;
Q=tf([3*tol,1],[tol^3,3*tol^2,3*tol,1]);
bode(Q);
dcgain(Q)
OD1=1/(1-Q);
OD2=Q/Gn;