A small-scale hyperacute compound eye featuring active eye tremor: application to visual stabilization, target tracking, and short-range odometry

Abstract

In this study, a miniature artificial compound eye (15 mm in diameter) called the curved artificial compound eye (CurvACE) was endowed for the first time with hyperacuity, using similar micro-movements to those occurring in the fly's compound eye. A periodic micro-scanning movement of only a few degrees enables the vibrating compound eye to locate contrasting objects with a 40-fold greater resolution than that imposed by the interommatidial angle. In this study, we developed a new algorithm merging the output of 35 local processing units consisting of adjacent pairs of artificial ommatidia. The local measurements performed by each pair are processed in parallel with very few computational resources, which makes it possible to reach a high refresh rate of 500 Hz. An aerial robotic platform with two degrees of freedom equipped with the active CurvACE placed over naturally textured panels was able to assess its linear position accurately with respect to the environment thanks to its efficient gaze stabilization system. The algorithm was found to perform robustly at different light conditions as well as distance variations relative to the ground and featured small closed-loop positioning errors of the robot in the range of 45 mm. In addition, three tasks of interest were performed without having to change the algorithm: short-range odometry, visual stabilization, and tracking contrasting objects (hands) moving over a textured background.

A novel hyperacute gimbal eye to implement precise hovering and target tracking on a quadrotor

“…However, to be able to track more complex targets, in natural environements, with texture and and objects, this simple eye could be replace by another minimalistic bio-inspired eye [37]. Indeed, it was proven that such an eye was able to perform visual odometry tasks, and could also be used to track a target moving over a textured background [30].…”

“…The focallength of each lens was adjusted to implement a Gaussian angular sensitivity ∆ρ of 3.7°for each pixel, and an inter-pixel angle ∆φ of approximatively 3.9°(see figure 2). As described in (see [24], [28], [30]), we need an active vibration system Fig. 1.…”

Insect-inspired vision for autonomous vehicles

“…However, several authors have integrated micro movements of this kind into their artificial visual sensors, and the results obtained have shown that they were able to locate a contrasting target with much greater accuracy (up to 700-fold) than that achieved using optical systems alone [22,57]. Thanks to this hyperacuity, it was recently established using a biorobotic approach that a contrasting moving target (moving hands) could be located on a textured background and the distance travelled by a micro robot flying above a textured plane could be measured by processing the visual signals conveyed by the 40 ommatidia in a vibrating artificial compound eye [8]. The presence of hyperacuity has not yet been clearly determined in insects, but a highly counter-intuitive principle in which coarse and blurry vision (due to the Gaussian angular sensitivities of the photoreceptors) is combined with vibration seems to be able to give a more accurate perception of the world.…”

Bio-Inspired Principles Applied to the Guidance, Navigation and Control of UAS

“…Optic flow is a popular technique for the real-time stabilisation and control of small-size rotorcraft [23,31,45,[94][95][96][97].…”