Design and Simulation of a Circadian Lighting Control System Using Fuzzy Logic Controller for LED Lighting Technology

Abstract

This paper introduces a fuzzy logic-based circadian lighting control system using flexibility of Light-Emitting Diode (LED) lighting technology to synchronise artificial lighting with circadian (natural) lighting Correlated Colour Temperature (CCT) characteristics. Besides for vision acuity, the Non-Imaging Forming effects of lighting affect human circadian rhythms. Past works in spectrally tuning CCT or Spectral Power Distribution of lighting have used conventional Proportional-Integral-Derivative (PID) control system architecture, where the modelling process of system transfer functions was mathematically complex, especially for nonlinear systems. A methodology of regulating lighting CCT is employed in a 7×5 fuzzy logic rules matrix in a Fuzzy Logic Controller (FLC) system, to closely replicate natural lighting CCT characteristics for indoor lighting. A reference lookup table was devised to store desired CCT values arbitrarily with respect to time mark in a day, which acts as an outdoor circadian stimulus and guides the FLC. The FLC compensates for the lack of CCT in lighting space. Simulation results show acceptable CCT output values conforming to circadian lighting parameters at a time in a day compared to the lookup table targets. Deviation from blackbody curve was within ±0.003 using CCT Duv checking. The system did not produce an overshoot (0.0%) with a steady state (zero error) reached after the fourth iteration. Also, rise time was calculated to be 1 iteration. This approach could be further enhanced to cater for additional custom needs in many built environments. Future works may consider connecting more sensors to capture real-time outdoor CCT values for practical regulation.

Natural light optimization in an existing primary school: human centred design and daylight retrofitting solutions for students wellbeing

“…This provides considerable reduction of mental fatigue and hyperactivity in children, as proved by recent literature researches [7,11,15]. Our methodological approach showed how any lighting project, based on the integration of natural and artificial light, should be based on the use of digital technologies, DALI wireless, tunable white drivers, widely available today, to provide light quality and vision/perception quality [1,4,23,24]. These integrated solutions not only produce people visual comfort and global well-being but, at the same time, important energy consumption reduction, with consequent positive effects on the environment.…”

“…It is a sign of success, but also of acquired complexity. Tackling a lighting project only by modelling and pragmatic point of views, can lead to a solution, meeting the suggested limits and energy consumption reduction, but this raises the question of the misunderstanding concept of "scheme" that can reduce the project to quantity and quality of light control [1][2][3][4][5]. Moreover, the existing, renovated/refurbished buildings and especially the historic ones, do not always meet the standard requirements, often due to their use changed over time.…”

“…Natural light is fundamental for visual well-being and health, effectiveness and rational use of energy for any kind of building [1][2][3][4][5]. As a matter of fact, some literature studies have highlighted the importance of control and design the natural light effectiveness for energy consumption reduction and guaranteeing daylight autonomy [5][6][7][8].…”

“…As a matter of fact, some literature studies have highlighted the importance of control and design the natural light effectiveness for energy consumption reduction and guaranteeing daylight autonomy [5][6][7][8]. Some researches [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] have provided specific lighting design methods to assure the proper lighting conditions for different uses and activities, especially in school buildings at the proper time and proper area of each classroom, in compliance with the CIE suggestions [15,16]. Some authors by means of several climate based daylight (CBD) simulations, have provided the effective combination between natural and artificial light on spatial daylight autonomy and annual sunlight exposure metrics [17].…”

“…Other studies have investigated lighting and sources design, referring to the circadian light of tunable white technology with dynamic adjusting of spectrum and intensity [4]. They have also suggested a useful methodological approach for smart lighting system design, considering dynamic colour temperature and emission spectrum changes, together with user visual comfort criteria [4]. In particular, other studies on this matter have proposed an advanced smart self-calibrating lighting control system for energy consumption reduction [11].…”