3,188 research outputs found
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Developing Flexible, Networked Lighting Control Systems That Reliably Save Energy in California Buildings
An important strategy to meet California's ambitious energy efficiency goals is to use innovative wireless communications, embedded sensors, data analytics and controls to significantly reduce lighting energy use in commercial buildings. This project developed a suite of networked lighting solutions to further this goal. The technologies include a platform for low-cost sensing, distributed intelligence and communications, the âPermaMote,â which is a self-powered sensor and controller for lighting applications. The project team also developed a task ambient daylighting system that integrates sensors with data-driven daylighting control using an open communication interface, called the âReadings-At-Deskâ (RAD) system. To address the problem of building occupants being confused about how to operate traditional lighting control systems, the research team created content that could be the basis for a user interface standard for lighting controls. Finally, to address the difficulty of ensuring that advanced lighting control systems actually deliver their promised energy savings, the project team developed a new method for evaluating and specifying lighting systemsâ performance.
The research team validated these technologies in the laboratory, showing significant lighting energy savings, up to 73% for the PermaMote sensor system from occupancy control and daylight dimming features, compared to the same light source (LED replacement lamps) operated via simple on/off scheduling. The project team also developed a proposed standard lighting data model and user interface elements, which were contributed to the ANSI Lighting Systems Committee (C137) for standardization. Existing data models are incomplete and inconsistent, whereas the lighting-specific data model developed here is clear and comprehensive, to serve as a starting point for creating common, universally agreed upon semantic definitions of key lighting parameters, to promote interoperability. For the task on verifiable performance of lighting systems, the project team developed a more effective metric for capturing the actual energy impact of a lighting system over time â the energy usage intensity (kWh/ft2/year). Three commercial lighting systems were tested in FLEXLABÂź using this new metric, and the tests show a wide range in the accuracy of the self-reported energy-use metric, from 0.5% to 28% error compared to direct measurement of lighting energy using dedicated submeters. Overall, the project team estimates that these advanced technologies can reduce California office lighting energy use by 20% (above and beyond normal advanced lighting controls mandated by Title 24), resulting in about 1,600 GWh/year in savings
Exposure-Tolerant Imaging Solution forCultural Heritage Monitoring
This paper describes a simple and cheap solution specifically designed for monitoring the degradation of thin coatings employed for metal protection. The proposed solution employs a commercial photocamera and a frequency-domain-based approach that is capable of highlighting the surface uniformity changes due to initial corrosion. Even though the proposed solution is specifically designed to monitor the long-time performance of protective coatings employed for the restoration of silver artifacts, it can be successfully used also for assessing the conservation state of other ancient metallic works of art. The proposed solution is made tolerant to exposure changes by using a procedure for sensor nonlinearity identification and correction, does not require a precise lighting control, and employs only free open-source software, so that its overall cost is very low and can be used also by not specifically trained operator
Methods for measuring work surface illuminance in adaptive solid state lighting networks
The inherent control flexibility implied by solid-state lighting - united with the rich details offered by sensor networks - prompts us to rethink lighting control. In this research, we propose several techniques for measuring work surface illuminance and ambient light using a sensor network. The primary goal of this research is to measure work surface illuminance without distraction to the user. We discuss these techniques, including the lessons learned from our prior research. We present a new method for measuring the illuminance contribution of an arbitrary luminaire at the work surface by decomposing the modulated light into its fundamental and harmonic components.Massachusetts Institute of Technology. Media Laborator
CoBe -- Coded Beacons for Localization, Object Tracking, and SLAM Augmentation
This paper presents a novel beacon light coding protocol, which enables fast
and accurate identification of the beacons in an image. The protocol is
provably robust to a predefined set of detection and decoding errors, and does
not require any synchronization between the beacons themselves and the optical
sensor. A detailed guide is then given for developing an optical tracking and
localization system, which is based on the suggested protocol and readily
available hardware. Such a system operates either as a standalone system for
recovering the six degrees of freedom of fast moving objects, or integrated
with existing SLAM pipelines providing them with error-free and easily
identifiable landmarks. Based on this guide, we implemented a low-cost
positional tracking system which can run in real-time on an IoT board. We
evaluate our system's accuracy and compare it to other popular methods which
utilize the same optical hardware, in experiments where the ground truth is
known. A companion video containing multiple real-world experiments
demonstrates the accuracy, speed, and applicability of the proposed system in a
wide range of environments and real-world tasks. Open source code is provided
to encourage further development of low-cost localization systems integrating
the suggested technology at its navigation core
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Building a Bidirectional Visible Light Communication Link: Challenges and Contributions
Visible Light Communication is a new information transmission method that involves sending data through light emitting diodes and photo-diodes via the visible light spectrum. It has strong applications in improving security for IoT (Internet of Things) devices. This paper describes a hardware-first approach to building a visible light communication (VLC) link. A VLC link was designed by choosing the simplest possible circuit and software and then incrementally improving it as challenges such as ambient lighting noise and data rate limitations were encountered. This link was used with two main communication protocols: On-off keying (OOK), and Frequency-Shift Keying. The paper describes a design for a fast, robust system using both protocols that also allows for an adjustable data rate. Because many issues were encountered along the way, the paper presents several possible sources of noise and data rate limitations and how to remove this noise and limitations. Finally, the paper also describes extensions to the design to make it bidirectional, more robust, and faster.Electrical and Computer Engineerin
Etude et réalisation d'un systÚme de communications par lumiÚre visible (VLC/LiFi). Application au domaine automobile.
The scientific problematic of this PhD is centered on the usage of Visible LightCommunications (VLC) in automotive applications. By enabling wireless communication amongvehicles and also with the traffic infrastructure, the safety and efficiency of the transportation canbe substantially increased. Considering the numerous advantages of the VLC technologyencouraged the study of its appropriateness for the envisioned automotive applications, as analternative and/or a complement for the traditional radio frequency based communications.In order to conduct this research, a low-cost VLC system for automotive application wasdeveloped. The proposed system aims to ensure a highly robust communication between a LEDbasedVLC emitter and an on-vehicle VLC receiver. For the study of vehicle to vehicle (V2V)communication, the emitter was developed based on a vehicle backlight whereas for the study ofinfrastructure to vehicle (I2V) communication, the emitter was developed based on a traffic light.Considering the VLC receiver, a central problem in this area is the design of a suitable sensorable to enhance the conditioning of the signal and to avoid disturbances due to the environmentalconditions, issues that are addressed in the thesis. The performances of a cooperative drivingsystem integrating the two components were evaluated as well.The experimental validation of the VLC system was performed in various conditions andscenarios. The results confirmed the performances of the proposed system and demonstrated thatVLC can be a viable technology for the considered applications. Furthermore, the results areencouraging towards the continuations of the work in this domain.La problĂ©matique scientifique de cette thĂšse est centrĂ©e sur le dĂ©veloppement decommunications par lumiĂšre visible (Visible Light Communications - VLC) dans lesapplications automobiles. En permettant la communication sans fil entre les vĂ©hicules, ou entreles vĂ©hicules et lâinfrastructure routiĂšre, la sĂ©curitĂ© et l'efficacitĂ© du transport peuvent ĂȘtreconsidĂ©rablement amĂ©liorĂ©es. Compte tenu des nombreux avantages de la technologie VLC,cette solution se prĂ©sente comme une excellente alternative ou un complĂ©ment pour lescommunications actuelles plutĂŽt basĂ©es sur les technologies radio-frĂ©quences traditionnelles.Pour rĂ©aliser ces travaux de recherche, un systĂšme VLC Ă faible coĂ»t pour applicationautomobile a Ă©tĂ© dĂ©veloppĂ©. Le systĂšme proposĂ© vise Ă assurer une communication trĂšs robusteentre un Ă©metteur VLC Ă base de LED et un rĂ©cepteur VLC montĂ© sur un vĂ©hicule. Pour l'Ă©tudedes communications vĂ©hicule Ă vĂ©hicule (V2V), l'Ă©metteur a Ă©tĂ© dĂ©veloppĂ© sur la base dâun pharearriĂšre rouge de voiture, tandis que pour l'Ă©tude des communications de l'infrastructure auvĂ©hicule (I2V), l'Ă©metteur a Ă©tĂ© dĂ©veloppĂ© sur la base d'un feu de circulation. ConsidĂ©rant lerĂ©cepteur VLC, le problĂšme principal rĂ©side autour dâun capteur appropriĂ©, en mesured'amĂ©liorer le conditionnement du signal et de limiter les perturbations dues des conditionsenvironnementales. Ces diffĂ©rents points sont abordĂ©s dans la thĂšse, dâun point de vue simulationmais Ă©galement rĂ©alisation du prototype.La validation expĂ©rimentale du systĂšme VLC a Ă©tĂ© rĂ©alisĂ©e dans diffĂ©rentes conditions etscĂ©narii. Les rĂ©sultats dĂ©montrent que la VLC peut ĂȘtre une technologie viable pour lesapplications envisagĂ©es
A sub-mW IoT-endnode for always-on visual monitoring and smart triggering
This work presents a fully-programmable Internet of Things (IoT) visual
sensing node that targets sub-mW power consumption in always-on monitoring
scenarios. The system features a spatial-contrast binary
pixel imager with focal-plane processing. The sensor, when working at its
lowest power mode ( at 10 fps), provides as output the number of
changed pixels. Based on this information, a dedicated camera interface,
implemented on a low-power FPGA, wakes up an ultra-low-power parallel
processing unit to extract context-aware visual information. We evaluate the
smart sensor on three always-on visual triggering application scenarios.
Triggering accuracy comparable to RGB image sensors is achieved at nominal
lighting conditions, while consuming an average power between and
, depending on context activity. The digital sub-system is extremely
flexible, thanks to a fully-programmable digital signal processing engine, but
still achieves 19x lower power consumption compared to MCU-based cameras with
significantly lower on-board computing capabilities.Comment: 11 pages, 9 figures, submitteted to IEEE IoT Journa
Indoor Visible Light Communication:A Tutorial and Survey
Abstract
With the advancement of solid-state devices for lighting, illumination is on the verge of being completely restructured. This revolution comes with numerous advantages and viable opportunities that can transform the world of wireless communications for the better. Solid-state LEDs are rapidly replacing the contemporary incandescent and fluorescent lamps. In addition to their high energy efficiency, LEDs are desirable for their low heat generation, long lifespan, and their capability to switch on and off at an extremely high rate. The ability of switching between different levels of luminous intensity at such a rate has enabled the inception of a new communication technology referred to as visible light communication (VLC). With this technology, the LED lamps are additionally being used for data transmission. This paper provides a tutorial and a survey of VLC in terms of the design, development, and evaluation techniques as well as current challenges and their envisioned solutions. The focus of this paper is mainly directed towards an indoor setup. An overview of VLC, theory of illumination, system receivers, system architecture, and ongoing developments are provided. We further provide some baseline simulation results to give a technical background on the performance of VLC systems. Moreover, we provide the potential of incorporating VLC techniques in the current and upcoming technologies such as fifth-generation (5G), beyond fifth-generation (B5G) wireless communication trends including sixth-generation (6G), and intelligent reflective surfaces (IRSs) among others
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