function [dotl,omega_2] = fermeture_cinematique(theta_2,l,theta_1,omega_1)
e=0.109;
R=0.0792;
theta_1_star=theta_1+pi/4;
omega_2=(l/R)*omega_1/cos(theta_2-theta_1_star);
dotl=-R*omega_2*sin(theta_2-theta_1_star);