Search (and execute) for tile message as:
GET POS : get position of agents
GET FOR1 : get force of sensor 1
GET FOR2 : get force of sensor 2
PUT VEL : put new velocity of agents
PUT ANGLE : put new direction of robot
PUT BEH : put actual behavior we are using
Calculate an approssimate sign of a parameter using a function that is continuos
and has the first and second differential continuos (so it can be used by
Newton-Rapson algorithm