Steering by Gazing: An Efficient Biomimetic Control Strategy for Visually Guided Micro Aerial Vehicles

OSCAR II is a twin-engine aerial demonstrator equipped with a monocular visual system, which manages to keep its gaze and its heading steadily fixed on a target (i.e., a dark edge or a bar) in spite of the severe random perturbations applied to its body via a ducted fan. The tethered robot stabilizes its gaze on the basis of two oculomotor reflexes (ORs) inspired by studies on animals: 1) a visual-fixation reflex (VFR) and 2) a vestibulo-ocular reflex (VOR). One of the key features of this robot is that the eye is decoupled mechanically from the body about the vertical (i.e., yaw) axis. To meet the conflicting requirements of high accuracy and fast ocular responses, a miniature (2.4 g) voice-coil motor (VCM) was used, which enables the eye to make a change of orientation with an unusually short rise time (19 ms). The robot, which was equipped with a high-bandwidth (7 Hz) ¿VOR,¿ which is based on an inertial microrate gyro, is capable of accurate visual fixation as long as there is light. The robot is also able to pursue a moving target in the presence of erratic gusts of wind. Here, we present the two interdependent control schemes driving the eye in the robot and the robot in space with no knowledge of the robot's angular position. This ¿steering-by-gazing¿ control strategy, which is implemented on this lightweight (100 g) miniature aerial robot, demonstrates the effectiveness of this biomimetic visual/inertial heading control strategy.