Km = 0.00767; Kg = 3.7; Rm = 2.6; r = 0.00635;
M = 0.522; m = 0.231; g = 9.81; L = 0.305; J = 0;

D1 = (J+m*L^2)*(M+m)-m^2*L^2;
alpha = m*g*L*(M+m)/D1;
beta = m*L/D1;
gamma = m^2*g*L^2/D1;
delta = (J+m*L^2)/D1;
alpha1 = Km*Kg/Rm/r;
alpha2 = Km^2*Kg^2/Rm/r^2;

A = zeros(4); A(1,3) = 1; A(2,4) = 1;
A(3,2) = -gamma; A(3,3) = -alpha2*delta;
A(4,2) = alpha; A(4,3) = alpha2*beta;
B = zeros(4,1); B(3) = alpha1*delta; B(4) = -alpha1*beta;