Visual Odometry and Low Optic Flow Measurement by Means of a Vibrating Artificial Compound Eye

Abstract

In this study, a tiny artificial compound eye (diameter 15mm) named CurvACE (which stands for Curved Artificial Compound Eye), was endowed with hyperacuity, based on an active visual process inspired by the retinal micro-movements occurring in the fly’s compound eye. A periodic (1-D, 50-Hz) micro-scanning movement with a range of a few degrees ($5^\circ$) enables the active CurvACE to locate contrasting objects with a 40-fold greater accuracy which was restricted by the narrow interommatidial angle of about $4.2^\circ$. This local hyperacuity was extended to a large number of adjacent ommatidia in a novel visual processing algorithm, which merges the output signals of the local processing units running in parallel on a tiny, cheap micro-controller requiring very few computational resources. Tests performed in a textured (indoor) or natural (outdoor) environment showed that the active compound eye serves as a contactless angular position sensing device, which is able to assess its angular position relative to the visual environment. As a consequence, the vibrating compound eye is able to measure very low rotational optic flow up to $20^\circ /s$ and perform a short range odometry knowing the altitude, which are two tasks of great interest for robotic applications.