A miniature biomimetic gaze control system

For any sighted mobile creature, whether it be natural or artificial, stabilizing the visual system is a much more crucial issue than that of preventing a snapshot from being blurred by the unsteadiness of a human photographer. The more immune the eye of an animal or a robot is to various kind of disturbances such as body or head movements of all kinds, the less troublesome it will be for the visual system to carry out its many information processing tasks when walking or flying in unknown environments. The gaze control system that we describe In this work takes a lesson from the vestibulo ocular reflex (VOR) that is known to contribute to the stabilization of the human eyes. The originality and performances of the control system arise from the merging of two sensory modalities: (a) a retinal position signal is yielded by a novel piezo-based visual sensor called OSCAR (optical sensor for the control of autonomous robots); and (b) a VOR reflex is merged with a visual smooth pursuit reflex. Our gaze controller involves a feedforward eye control based on measurements of the angular head speed by a rate gyro. The performances of the gaze controller were tested on-board a miniature (5 grams) oculomotor system, which makes use of the OSCAR visual sensor. The combined visual/inertial sensory-motor controller enables the gaze to be stabilized within a 12-times smaller range than the perturbing head movements, which were applied here at frequencies of up to 3 Hz with an amplitude of 6° peak-to-peak. This is a relatively high standard of performance in terms of rejecting head movement disturbances; in any case, these performances are comparable to those which the human visual system is capable of.