Biorobotics researchers at the Institut des Sciences du Mouvement (Aix Marseille University) have developed the BeeRotor, a tethered flying robot that adjusts its speed and follows terrain without an accelerometer or the measurement of altitude.
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Optic flow sensors, inspired by insect vision, allow the BeeRotor to adjust its speed and avoid objects. With a weight of 80 g and a length of 47 cm, the device can independently avoid vertical obstacles in a tunnel with moving walls (see video below):
To measure optic flow, environmental contrasts, and motion, BeeRotor is equipped with 24 photodiodes, distributed at the top and the bottom of its eye. As in insects, the speed at which scenery feature moves from one pixel to another provides the angular velocity of the flow.
BeeRotor has three feedback loops, which act as three different reflexes that directly make use of the optic flow. The first feedback loop changes altitude, the second controls speed, and the final loop stabilizes the eye in relation to the local slope.
By eliminating bulky accelerometers and inertial reference systems, the development could enable lighter robots and technologies.
SOURCE: CNRS/Aix Marseille Université; http://www2.cnrs.fr/sites/en/fichier/cp_beerotor_ok_en.pdf