function [value,isterminal,direction] = eventRRs(t,x)

global  L1 L2 

vn = L1*x(2)*cos(x(1))+L2*x(4)*cos(x(3));

vt = -L1*x(2)*sin(x(1))-L2*x(4)*sin(x(3));
     
value = [ vn vt ];


isterminal = [1 1];

direction = [0 0];