Design method of state feedback controller

Can you explain the design method of a state feedback controller using MATLAB and Simulink, and the methods of position and velocity control using it?

I have designed an observer using MATLAB and Simulink. Now, I want to add position control and velocity control to this model. How can I do this? If there are any other methods besides the one I used, please let me know so that I can consider them as well.

The MATLAB code is as follows:

close all;

clear;

clc;

J = 2.09e-5;

B = 0.00002;

Kt = 0.042;

Kb = 0.042;

R = 8.4;

L = 1.16;

Ae = [0 1 0 0

0 -B/J Kt/J 1/J

0 -Kb/L -R/L 0

0 0 0 0];

Be = [0 0 1/L 0]';

Ce = [1 0 0 0];

De = 0;

% Observability

obsv(Ae, Ce)

rank(obsv(Ae, Ce))

% eigenvalue

eigen = [-15 -15 -15 -15];

Lgian = acker(Ae', Ce', eigen)

L1 = Lgian(1)

L2 = Lgian(2)

L3 = Lgian(3)

L4 = Lgian(4)

The following is a model created for the motor and observation device through state equations.

The lines indicating the input and output of disturbance (d) in the picture are not shown, but they are actually connected.