Proposal for a Beacon-type Intelligent Lighting System Automating the Toggling of the Occupancy Status Using a BLE Beacon

Transcription

1 214 Int'l Conf. Artificial Intelligence ICAI'16 Proposal for a Beacon-type Intelligent Lighting System Automating the Toggling of the Occupancy Status Using a BLE Beacon Sota NAKAHARA 2, Mitsunori MIKI 1, Kohei YAMAGUCHI 2, Shinya DAINAKA 2, and Hiroto AIDA 1 1 Department of Science and Engineering, Doshisha University, Kyoto, Japan 2 Graduate School of Science and Engineering, Doshisha University, Kyoto, Japan Abstract We research and develop an Intelligent Lighting System to realize the illuminance levels required by each office worker.under the current Intelligent Lighting System, each worker manually toggles the occupancy status of their seat, but as a result of demonstration test, it was found that there were many workers who did not toggle it appropriately. Consequently, unnecessary lamps remained on even though there was no worker, reducing energy efficiency. This study thus proposes a Beacon-type Intelligent Lighting System. As a result of verifying the effectiveness of the Beacon-type Intelligent Lighting System proposed, it was found to be able to detect correctly the occupancy status of a seat and the location of a worker and satisfy the illuminance requirement by the worker. Keywords: LightingIntelligent Lighting System, BLE Beacon, Attendance Management 1. Introduction In recent years, there has been a rise in attention to approaches for improving the intellectual productivity, creativity and comfort of office workers[1]. A study by Boyce et al. have revealed that providing the brightness (illuminance) optimized for the work of each worker is effective from the viewpoint of improving the lighting environment[2]. Against this backdrop, the authors have undertaken studies on Intelligent Lighting Systems aimed at improving worker comfort in offices and reducing power consumption by lightings[3],[4]. An Intelligent Lighting System realizes the illuminance level requested by each worker (target illuminance) at the relevant illuminance sensor position with a minimum power consumption. An office with an Intelligent Lighting System is expected to allow workers to work in luminous environments customized for each of them, which will improve their comfort and reduce their stress. Moreover, providing the necessary levels of luminance at areas in need can lower the average illuminance in the whole room, which will result in a significant reduction of power consumption. The target illuminance refers to brightness desired by a worker and is set by the illuminance sensor button on the PC on his/her desktop or the physical button installed on an illuminance sensor. As these advantages of Intelligent Lighting Systems are recognized, verification experiments have been underway at several offices in Tokyo, which have successfully realized required illuminance levels at the points where they are required, realizing high energy efficiency[5]. The Intelligent Lighting System judges that it is not required to provide illuminance to a seat unoccupied by any worker. By dimming or turning off lighting for an area around the seat in such a manner as not to affect working space of other workers, the system realizes even higher energy saving. As a result of demonstration tests at real offices, however, it was found that workers did not appropriately toggle the occupancy status of their seat. It was thus found that there were lighting fixtures which provided brightness more than required even though there was no worker. We thus propose a Beacon-type Intelligent Lighting System, which identifies the location of a worker by using a BLE beacon (hereinafter "beacon") and a smartphone to automate the toggling of the occupancy status in the Intelligent Lighting System. The Beacon-type Intelligent Lighting System determines the degree of proximity between a beacon and a smartphone by using the signal strength of radio wave transmitted by the beacon and received by the smartphone and then determines whether a seat is occupied or not by using the degree of proximity. It is intended to improve the convenience of the Intelligent Lighting System for workers by having the system toggle the occupancy status of a seat, which was previously toggled manually by a worker, by using a beacon and a smartphone. 2. Intelligent Lighting System 2.1 Overview An Intelligent Lighting System realizes an illuminace level desired by the user while minimizing energy consumption by changing the luminous intensity of lightings. The Intelligent Lighting System, as indicated in Fig.1, is composed of lighting fixtures equipped with lighting control device, illuminance sensors, and electrical power meters, with each element connected via a network. A lighting control device evaluates the effectiveness of the current lamp lighting pattern on the basis of illuminance information obtained from an illuminance sensor and power information obtained from a power meter. It is intended to minimize power consumption while satisfying the illuminance constraint required by each worker by repeatedly

2 Int'l Conf. Artificial Intelligence ICAI' W Power meter Electric Power Consumption Control device Control signal Network Sensor ID Current illuminance Target illuminance Lighting Fixture Illuminance sensor Fig. 1: Configuration of Intelligent Lighting System changing a lamp lighting pattern slightly and evaluating its effectiveness. Intelligent Lighting System controls use a control algorithm (Adaptive Neighborhood Algorithm using Regression Coefficient: ANA/RC) based on Simulated Annealing (SA)[3], [6]SA is a general-purpose local search method in which an approximate solution within a range near the current solution is generated and the approximate solution is accepted if the objective function improves. Taking the luminance of the lighting fixture as design variable, it randomly varies the luminance of each lighting fixture in each search to an extent unnoticeable by workers to search an optimum lighting pattern. By repeating lighting control attempts of about a second 30 to 100 times, an Intelligent Lighting system realizes the target illuminance level requested by each worker. The flow of control by the Intelligent Lighting System using is shown below. (1) Set the target illuminance of each illuminance sensor. (2) Turn on each lighting fixture at the initial luminance. (3) Obtain values measured by illuminance sensors and a power meter. (4) Calculate evaluation value in accordance with the objective function described below. (5) Generate the next luminance in accordance with the illuminance/luminance influence factor and light the lighting fixtures at the next luminance. (6) Obtain values measured by illuminance sensors and a power meter. (7) Calculate the evaluation value under the lighting condition in (5). (8) If the evaluation value of the objective function is improved, accept the next luminance; otherwise revert to the original luminance. (9) Return to step (3). An illuminance/luminance influence factor is set for each lighting fixture in accordance with its positional relationship with each illuminance sensor, and directionality is given to a random change in luminance in accordance with the degree of the effect. The objective function of each function is given by Equation (1). f i = P + w n g i (1) i=1 { 0 (Lci Lt g i = i ) 0 R i (Lc i Lt i ) 2 (Lc i Lt i ) < 0 { ri r R i = i T 0 r i < T n:number of illuminance sensors, w:weight P :power consumption[w], L c :current illuminance[lx], L t :target illuminance[lx] r i :illuminance/luminance influence factor[lx/cd] T :threshold The objective function given by Equation (1) is composed of power consumption P and illuminance constraint g i and calculated for each lighting fixture. Penalty g i whose constraint is the target illuminance of each illuminance sensor changes by the illuminance/luminance influence factor.the system functions in such a manner that only a lighting fixture with a large illuminance/luminance influence factor is significantly affected by penalty.in addition, by setting the threshold T to illuminance/luminance influence factor r i, lighting fixtures affecting a given illuminance sensor can be narrowed down to those in its proximity. This enables controlling lighting fixtures far from the illuminance sensor so as to minimize power consumption. The illuminance/luminance influence factor is a value indicating the relationship between an illuminance value obtained from an illuminance sensor and the luminance of a lighting fixture. The illuminance/luminance influence factor is given by Equation (2). I = RL (2) Iilluminance [lx]lluminance [cd] Rilluminance/luminance influence factor [lx/cd] Illuminance/luminance influence factor R is a value that depends on an illuminance environment and can be regarded as a constant so long as there is no change in an illuminance environment. Since desks are infrequently moved in an ordinary office, it is possible to measure an illuminance/luminance influence factor in advance in an environment into which the Intelligent Lighting System is to be introduced by turning on and off its lighting fixtures one by one. 2.2 Simulation based control In the Intelligent Lighting System described in the previous section, necessary illuminance is provided to necessary locations by repeatedly changing luminance by using an optimization method based on illuminance information obtained from each illuminance sensor and power consumption

3 216 Int'l Conf. Artificial Intelligence ICAI'16 information obtained from a power meter. This method enables flexible responses to various changes in a lighting environment including changes in the layout in an office, the displacement of illuminance sensors, the degradation of lighting fixtures, and the effect of external light. There are, however, many offices which do not have any window or hardly receive any daylight due to surrounding buildings even if they have a window. In such an environment, the effect of daylight need not be taken into account. In addition, in real offices in which demonstration tests for the Intelligent Lighting System were conducted, seats were often fixed, and the locations of illuminance sensors on desktops were determined in advance, resulting in no displacement of those sensors. Furthermore, as the service life of lighting fixtures have been prolonged in recent years owing to the spread of LED lighting fixtures, it is considered unnecessary to take the degradation of lighting fixtures into account in a short term. In such an environment, there is a method to control the Intelligent Lighting System which reduces the number of lighting control steps required to reach illuminance convergence[7]. This method searches for the optimal lamp lighting pattern without obtaining information from a power meter and illuminance sensors by estimating power information and illuminance information and repeating optimization on a computer using estimated values. By applying the lamp lighting pattern searched on a computer to lighting fixtures in a real environment, the target illuminance for each worker is realized by a single step of lighting control. The method also enables controlling the Intelligent Lighting System without an illuminance sensor because it estimates power and illuminance information on a computer. In what follows, an Intelligent Lighting System control method that reduces the number of lighting control steps required to reach illuminance convergence is called a simulation based control. Assuming an office environment without a change in an illuminance environment and an effect of external light, the proposed system used a simulation based control that does not use an Intelligent Lighting System as an Intelligent Lighting System control method. 3. Beacon A beacon is a device based on location technology using a low-power-consuming short-range radio technology named Bluetooth Low Energy (BLE). A beacon transmits its own identification information in a short range at a regular interval. The following information is transmitted by a beacon as identification information. proximityuuid a unique ID assigned for identifying the group to which it belong major the value for identifying beacons with the same UUID minor the value for identifying beacons with the same UUID and major Measured Power the measured value of the strength of signal received at a point 1 m from the beacon A smartphone estimates the approximate distance from a beacon by using the beacon s identification information it receives and received signal strength indicator (RSSI). 4. Beacon-type Intelligent Lighting System 4.1 Overview A Beacon-type Intelligent Lighting System is an Intelligent Lighting System that automates the toggling of the occupancy status of a seat by using a beacon and a smartphone. Fig. 2 gives a configuration diagram for a Beacontype Intelligent Lighting System. 164W Power meter Control device Network Smartphone Lighting Fixture Beacon Fig. 2: Configuration Diagram for a Beacon-type Intelligent Lighting System When a worker enters an office room and takes a seat, he/she puts a smartphone on the specified spot on the desk. Then his/her smartphone detects a beacon signal from a beacon placed on the desk and transmits an instruction to set the seat s status to "occupied" to the control PC. When the worker leaves the room, the smartphone detects that it is no longer able to receive a beacon signal and transmits an instruction to set the seat s status to "vacant" to the control PC. In this way, the occupancy status of a seat, which was toggled manually in the current Intelligent Lighting System, is toggled automatically. 4.2 System Configuration MyBeacon Pro MB004 Ac by Aplix was used as a beacon. This beacon was placed on each of workers desks. Consequently, in order to minimize interference with other beacons, the radio wave output from each beacon was set to the minimum at -20 dbm. The Intelligent Lighting System is controlled assuming that RSSI on a worker s smartphone is greater than the threshold for determining that the worker is

4 Int'l Conf. Artificial Intelligence ICAI' in proximity with the seat and that beacon signal is strongest at the position where the worker is seated. Shown below is the procedure starting with a worker s entrance into a room and ending with the system s setting the status of his/her seat to "occupied". (1) A worker enters a room (2) The worker s smartphone receives identification information from a beacon. (3) The smartphone transmits the received identification information of the beacon and the target illuminance set by the worker to the system. (4) The system identifies the location of the smartphone on the basis of identification information received from the smartphone and sets the occupancy status of the worker s seat to "occupied" and turns on lamps. The system sets the status to "vacant" when the conditions for the "occupied" status are no longer met. 5. RSSI Threshold Setting for Determining Seat Occupancy Status and RSSI Measurement Experiment 5.1 Overview This system uses RSSI on a worker s smartphone from a beacon placed on each desk to determine whether their seat is occupied or not. It was thus verified how RSSI changed in accordance with the distance between a beacon and a smartphone. 5.2 Experiment Environment RSSI was measured to see how it changes in accordance with the distance between a beacon and a smartphone. This measurement experiment was conducted in the Smart Office Laboratory Kochikan, Doshisha University. Table 1 shows equipment used, and Fig. 3 shows the experimental environment. Table 1: Equipment Used Beacon MyBeacon Pro MB004 Ac Smartphone iphone 4S A smartphone was placed at an interval of 0.1 m from a beacon, and RSSI on the smartphone was measured up to the maximum distance of 2.0 m. iphone 4S was used, and a beacon was placed on a desk in such a manner that its indicator lamp faces up. Measurement was made five times each in four directions. 5.3 Result of Measurement Fig. 4 shows the result of RSSI measurement experiment. Based on Fig. 4, it was found that the average RSSI decreases gradually up to the distance of 0.7m but does not change so much at a farther distance. This system assumes 2.0m F Beacon Desk Fig. 3: RSSI Measurement Experiment Environment Average RSSI [dbm] Distance from Beacon [m] Fig. 4: Result of RSSI Measurement that a beacon is placed on a desktop, with a smartphone to be placed on a specified spot on the desk. Therefore, the distance between a beacon and a smartphone is within about 0.2 m. The RSSI threshold in this system is thus set to -80 dbm. 6. System Operation Experiment 6.1 Overview Using the RSSI threshold for determining whether a seat is vacant or not obtained in the previous chapter, we developed a Beacon-type Intelligent Lighting System and conducted its operation experiment. The Intelligent Lighting System was controlled based on simulation and without using an illuminance sensor in conducting the operation experiment. The equipment used was the same as that for the RSSI measurement experiment: "MyBeacon Pro MB004 Ac" beacon by Aplix and iphone 4S smartphone. An illuminance sensor was placed on the desk of a subject worker in order to confirm that the Intelligent Lighting System works normally and satisfies the target illuminance. As with the RSSI experiment, this measurement experiment was conducted in the Smart Office Laboratory, Kochikan, Doshisha University.

5 218 Int'l Conf. Artificial Intelligence ICAI'16 Fig. 5 shows an environment in which the system operation experiment was conducted. D G F I Lighting Fixture Desk Beacon Fig. 5: System Operation Experiment Environment The flow of the movement of workers in this experiment is shown below. (1) Worker A (target illuminance: 300 lx) takes Seat 1. (2) Worker B (target illuminance: 500 lx) takes Seat 5. (3) Worker B moves to Seat 6. (4) Worker C (target illuminance: 700 lx) takes Seat 8. (5) Worker A leaves his/her seat. (6) Worker B leaves his/her seat. (7) Worker C leaves his/her seat. 6.2 Experiment Result Fig. 6 shows the history of illuminance at each seat under the proposed Beacon-type Intelligent Lighting System. Illuminance [lx] Seat 1 Seat 5 Seat 6 Seat C attends(700lx) C leaves B moves to seat B attends(500lx) B leaves 400 A leaves A attends(300lx) Time [sec] Fig. 6: History of Illuminance at Each Seat Based on Fig. 6, it is confirmed that, by using the proposed method, the system detected whether each worker is seated or not and changed the luminance of lighting fixtures to satisfy the target illuminance. For each worker, illuminance converged to the target illuminance as soon as it is detected whether the worker is seated or not, and the system controlled luminance to maintain the target illuminance thereafter. Then 250 seconds after the start of the experiment, Worker B, in addition to Worker A, took a seat. It was confirmed that the system realized the target illuminance for Worker B while satisfying the target illuminance required by Worker A being satisfied; 200 seconds afterward, Worker B moved to Seat 6, and the system provided the target illuminance required by Worker B at Seat 6 while satisfying the target illuminance required by Worker A. It was confirmed that the system worked to satisfy the target illuminance for each worker when Worker C took a seat subsequently. The system also correctly detected that each of Workers A, B, and C left their seat and precisely dimmed or turned off lighting fixture. The graph in Fig. 6 shows that illuminance at a seat decreased when it was vacated. Based on the result of this experiment, it can be said that the system can correctly manage the occupancy status of each worker s seat by detecting whether they are seated or not by using a beacon and smartphone and hence that a Beacon-type Intelligent Lighting System is useful. 7. Conclusion This paper described a Beacon-type Intelligent Lighting System, which automates the toggling of the occupancy status of each worker s seat by incorporating a seat occupancy detection system using a beacon into the current Intelligent Lighting System. In order to enable the system to detect whether a worker is seated or not correctly using a beacon and a smartphone, RSSI was measured as the distance between them was changed by 0.1 m to set the threshold for determining whether a worker is seated or not. Then the operation of the system was verified by simulating an actual office. As a result of the verification, it was confirmed that the Beacon-type Intelligent Lighting System operates properly. Although a beacon is now placed on a desk in an experiment, it is considered important to examine and experiment a variety of ways to place a beacon and consider introduction into a real office. References [1] Olli Seppanen, William J. Fisk, A Model to Estimate the Cost- Effectiveness of Improving Office Work through Indoor Environmental Control, Proceedings of ASHRAE, 2005 [2] P. R. Boyce, N. H. Eklund and S. N. Simpson, Individual Lighting Control: Task Performance", Mood and Illuminance JOURNAL of the Illuminating Engineering Society, pp , 2000 [3] M.Miki, T.Hiroyasu and K.Imazato, Proposal for an intelligent lighting system, and verification of control method effectiveness, Proc. IEEE CIS, 1, (2004). [4] M.Miki, K.Imazato and M.Yonezawa, Intelligent lighting control using correlation coefficient between luminance anc illuminance, Proc.IASTED Intelligent Systems and Control, 497[078], (2005). [5] Fumiya Kaku, Mitsunori Miki, Tomoyuki Hiroyasu, Masato Yoshimi, Shingo Tanaka, Takeshi Nishida, Naoto Kida, Masatoshi Akita, Junichi Tanisawa, Tatsuo Nishimoto, Construction of intelligent lighting system providing desired illuminance distributions in actual office environment, Artifical Intelligence and Soft Computing, vol. 6114, pp , 2010.

6 Int'l Conf. Artificial Intelligence ICAI' [6] S.Tanaka, M.Miki, T.Hiroyasu, M.Yoshikata, An Evolutional Optimization Algorithm to Provide Individual Illuminance in Workplaces, Proc IEEE Int Conf Syst Man Cybern, 2, (2009). [7] Shohei Matsushita, Sho Kuwajima, Mitsunori Miki, Hisanori Ikegami and Hiroto Aida, Reducing the Number of Times Lighting Control is required to reach Illuminance Convergence in the Intelligent Lighting System, The 2014 International Conference on Artificial Intelligence (ICAI2014)