A sun sensor implemented with an asynchronous luminance vision sensor

A sun sensor implemented with a spiking pixel matrix is reported. It is the very first one based on an asynchronous event-based pixel array. A paradigm associated to classic digital sun sensors is solved with this approach. Only pixels illuminated by the sun light are readout. Hence, the output data flow is quite reduced. The computational load to resolve the sun position is quite low, comparing to prior sensors. Sensor's latency is in the order of milliseconds. The advantages over implementations with APS pixels are more reduced data flow, less latency, and higher dynamic range.Universidad de Cádiz PR2016-072Ministerio de Economía y Competitividad TEC2015-66878- C3-1-RJunta de Andalucía TIC 2012-2338Office of Naval Research (USA) N00014141035

A Bio-Inspired AER Temporal Tri-Color Differentiator Pixel Array

This article investigates the potential of a bio-inspired vision sensor with pixels that detect transients between three primary colors. The in-pixel color processing is inspired by the retinal color opponency that are found in mammalian retinas. Color transitions in a pixel are represented by voltage spikes, which are akin to a neuron's action potential. These spikes are conveyed off-chip by the Address Event Representation (AER) protocol. To achieve sensitivity to three different color spectra within the visual spectrum, each pixel has three stacked photodiodes at different depths in the silicon substrate. The sensor has been fabricated in the standard TSMC 90 nm CMOS technology. A post-processing method to decode events into color transitions has been proposed and implemented as a custom interface to display real-time color changes in the visual scene. Experimental results are provided. Color transitions can be detected at high speed (up to 2.7 kHz). The sensor has a dynamic range of 58 dB and a power consumption of 22.5 mW. This type of sensor can be of use in industrial, robotics, automotive and other applications where essential information is contained in transient emissions shifts within the visual spectrumPeer reviewe

Centroid estimation method with sub-pixel resolution for event-based sun sensors

Resumen del trabajo presentado a la 17th Conference on Ph.D Research in Microelectronics and Electronics (PRIME), celebrada en Sardinia (Italia) del 12 al 15 de junio de 2022.A new method to obtain sub-pixel measurement resolution for sun sensors based on spiking pixels is presented. The procedure is intended to increase the resolution of the estimated angle. The method uses the profile of incident light to estimate the angle of the vector towards the sun with sub-pixel resolution. Read-out time, data bandwidth, and spatial resolution are improved. Experimental results are provided. The proposed method can be implemented in any asynchronous sun sensor operating in Time-to-First-Spike (TFS) mode.This work was supported by Proyectos de I+D+i de entidades públicas – Convocatoria 2020 P20_01206 (VERSO), by Ayudas a Proyectos de I+D+I Programa Operativo FEDER through Project US-1264940 (SPADARCH), by Spanish Government MINECO and European Regional Development Fund, (ERDF/FEDER) through Project RTI2018-097088-B-C31, and by ONR grant ONR NICOP N00014-19-1-2156.Peer reviewe

Sun Sensor Based on a Luminance Spiking Pixel Array

We present a novel sun sensor concept. It is the very first sun sensor built with an address event representation spiking pixel matrix. Its pixels spike with a frequency proportional to illumination. It offers remarkable advantages over conventional digital sun sensors based on active pixel sensor (APS) pixels. Its output data flow is quite reduced. It is possible to resolve the sun position just receiving one single event operating in time-to-first-spike mode. It operates with a latency in the order of milliseconds. It has higher dynamic range than APS image sensors (higher than 100 dB). A custom algorithm to compute the centroid of the illuminated pixels is presented. Experimental results are provided.Peer Reviewe