Balancing a ball on a beam article code.

balancing_ball_beam.m

k = -7.0071;
s = tf('s');
G = k/s^2;

% PD controller 
R = -(0.38 + 0.5*50/(1+50/s));

% Design a PD controller for the unit feedback loop
L = series(R,G);
sys = feedback(L, 1);

% Phase margin
margin(L)

% Step response
step(sys)

% Root locus
rlocus(L)