Failsafe ARDrone

If no joystick is used in Failsafe mode, the drone will slowly descend with a speed of 0.5m/s instead of setting the thrust to zero. This will prevent the drone from dropping out of the sky without the possibility to take over with the joystick. 
An example flight plan for the optitrack system. The flight plan specifies the flight area indicating where and at what height the waypoints can be positioned. 
Finally the gains for indoor flying with the ARDrone in the arena have been tuned.
Note that this is for the Optitrack ARDrone2, not for regular use. With the ARDrone it would drop out of the sky which is more damaging than slow decent, but only since the ARDrones detect contact with soft blades and stop spinning. Main reason is to prevent to much breaking of the X frame again after a hard landing. Failsafe happens e.g after "Fake" GPS loss, e.g to high in an optitrack sytem.