Lighting control analyzer

Abstract

The present invention relates to a lighting control analyzer (170), and a corresponding method (600), for determining occupancy behavior in an area (110, 200) illuminated by at least one lighting device (120a-c) controllable by a lighting controller (160). The lighting control analyzer is adapted to receive light settings (d) for control of the at least one lighting device, the light settings being determined by the lighting controller using a lighting control strategy for the area. The lighting control strategy represents a desired illumination of the area, based on presence information associated with the area. The lighting control analyzer is further adapted to determine the occupancy behavior, based on the light settings and the lighting control strategy. The occupancy behavior may comprise normal locations of occupants (401-417), how often occupants are normally located at different locations, and entrance points of the area.

Claims

1. A lighting control analyzer for determining occupancy behavior in an area arranged to be at least partly illuminated by at least one lighting device controllable by a lighting controller, the lighting control analyzer configured to: receive light settings for control of the at least one lighting device, the light settings being determined by the lighting controller using a lighting control strategy for said area, wherein the lighting control strategy represents a desired illumination of at least part of said area, based on presence information associated with at least one location in said area; and determine the occupancy behavior, based on the light settings and the lighting control strategy, wherein said light settings comprise dimming levels from at least one dimmer associated with said at least one lighting device, and wherein said lighting control analyzer is configured to determine an illuminance provided by said at least one lighting device at a plurality of locations in said area based on said received dimming levels.

2. The lighting control analyzer of claim 1, wherein the lighting control analyzer is configured to determine the occupancy behavior, based on light settings for a plurality of time instants.

3. The lighting control analyzer of claim 1, comprising a memory configured to store at least some of the received light settings, the lighting control analyzer configured to determine the occupancy behavior, based on at least some of the stored light settings.

4. The lighting control analyzer of claim 1, configured to: determine, based on the received light settings, a level of illumination of at least part of said area, said illumination provided by the at least one lighting device, and determine the occupancy behavior, based on the determined illumination level and the lighting control strategy.

5. The lighting control analyzer of claim 1, configured to determine momentary occupancy levels of locations in said area, based on illumination provided by said at least one lighting device and the lighting control strategy, wherein the momentary occupancy level of a location is indicative of the probability that said location is occupied at a certain time.

6. The lighting control analyzer of claim 5, further configured to determine, based on time averages of the determined momentary occupancy levels, at least one of: occupancy levels of locations in said area, and at least one occupant position in said area.

7. The lighting control analyzer of claim 1, further configured to: determine, when the received light settings change from a first state corresponding to a power saving mode for said at least one lighting device to a second state corresponding to an active mode for said at least one lighting device, at least one entrance point as a location in said area at which said at least one lighting device is activate to provide illumination.

8. The lighting control analyzer of claim 1, further configured to detect when the received light settings correspond to a power saving mode for said at least one lighting device, and to indicate, in response to said detection, at least one of the group comprising: a time point for determining a detection threshold for a presence sensor configured to provide information about presence of at least one occupant in at least one location of said area; a time point for determining light contribution in said area from light sources other than said at least one lighting device; a time point for determining a mapping between a light setting of a lighting device and illumination provided by the lighting device in at least one location of said area.

9. The lighting control analyzer of claim 1, further configured to: estimate an expected illumination of said area by said at least one lighting device, based on the determined occupancy behavior and the lighting control strategy; compare the expected illumination with illuminations corresponding to the received light settings for a plurality of time instants; and determine at least one light ingress location of said area, based on the comparisons.

10. The lighting control analyzer of claim 1, being further configured to provide information based on the determined occupancy behavior, said information including control parameters selected from the group comprising: control parameters for illumination of said area; control parameters for at least one of heating, ventilation and air conditioning of said area; and control parameters for controlling the flow of sunlight in said area.

11. The lighting control analyzer of claim 1, further configured to estimate potential power savings of the at least one lighting device, based on the received light settings, the lighting control strategy and the determined occupancy behavior.

12. A method of determining occupancy behavior in an area arranged to be at least partly illuminated by at least one lighting device, the method comprising: receiving light settings for control of the at least one lighting device, the light settings determined using a lighting control strategy for said area, wherein the lighting control strategy represents a desired illumination of at least part of said area, based on presence information associated with at least one location in said area; and determining the occupancy behavior, based on the light settings and the lighting control strategy, wherein said light settings comprise dimming levels from at least one dimmer associated with said at least one lighting device, said determining the occupancy behavior comprises determining an illuminance provided by said at least one lighting device at a plurality of locations in said area based on said received dimming levels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other objects, features and advantages of the present invention will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, in which:

(2) FIG. 1 schematically shows a lighting system comprising a lighting control analyzer according to an embodiment of the present invention;

(3) FIG. 2 shows a schematic top view of an office area;

(4) FIG. 3 shows a schematic top view of the office area of FIG. 2, with an example of actual occupancy levels and occupant positions;

(5) FIG. 4 shows a schematic top view of the office area of FIG. 2, with occupancy levels and occupant positions estimated by the lighting control analyzer in FIG. 1;

(6) FIG. 5 shows a schematic top view of the office area of FIG. 2, with light contribution from external light sources (the sun) and a light ingress location (windows), both estimated by the lighting control analyzer in FIG. 1; and

(7) FIG. 6 is a general outline of a method according to an embodiment of the present invention.

(8) All the drawings are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) With reference to FIG. 1, a lighting system according to an exemplifying embodiment of the invention will be described.

(10) FIG. 1 shows a lighting system 100 for controlling illumination of an area 110. The area 110 is illuminated by, e.g., three lighting devices 120a-c and presence of occupants (e.g. persons) 150 in the area 110 is monitored by, e.g., three presence sensors 130a-c (e.g. motion detectors, sound detectors, heat detectors or other types of presence sensors), each monitoring a part 140a-c of the area 110. It is to be noted that FIG. 1 serves as an example only and that in most practical situations the area 110 is larger, is illuminated by a larger number of lighting devices 120a-c and is monitored by a larger number of presence sensors 130a-c. In particular, the number of presence sensors 130a-c may be different from the number of lighting devices 120a-c.

(11) A lighting controller 160 receives presence information from the presence sensors 130a-c and, for control of the lighting devices 120a-c, determines light settings d based on the received presence information and a particular lighting control strategy. The light settings d determined by the lighting controller 160 may comprise one dimming level for each of the lighting devices 120a-c. The lighting control strategy may be, e.g., a localized illumination rendering, in which occupied parts of the area 110, i.e. the part 140a occupied by the person 150, are to be illuminated more (intensely) than unoccupied parts, i.e. parts 140b-c. Hence, the light settings d determined by the lighting controller 160 may be dimming levels for the lighting devices 120a-c, said light settings d controlling a lighting device 120a, arranged to illuminate the occupied part 140a of the region 110, to operate at full capacity, while the light settings d may control the other lighting devices 120b-c to operate at e.g. half capacity to reduce power consumption. When the occupant 150 moves to another part 140b of the area 110 (not shown in FIG. 1, as only one position of the occupant is depicted), a presence sensor 120b will detect his/her presence and the lighting controller 160 will determine new light settings d, causing a lighting device 120b to be adapted to illuminate the newly occupied part 140b of the area 110 and to operate at full capacity while the other lighting devices 120a and 120b may operate, e.g., at half capacity.

(12) A lighting control analyzer 170 may be connected to the lighting controller 160. With reference to FIGS. 1 and 6, an exemplifying embodiment of the lighting control analyzer 170 shown in FIG. 1 and adapted to perform the method illustrated in FIG. 6 will be described. The method 600 may comprise receiving 630 the light settings d, for example regularly or as often as the light settings are updated by the lighting controller 160 (e.g. once a second, ten times a second, or a hundred times a second). Optionally, the method 600 may comprise storing 640 the received light settings d, e.g., in a memory 171 arranged in the lighting control analyzer 170.

(13) The lighting control analyzer 170 has information about the lighting control strategy used by the lighting controller 160 to determine the light settings d based on the presence information. For example, the method 600 may optionally comprise obtaining 620 this information, e.g., from the lighting controller 160. The method 600 may further comprise determining 650 occupancy behavior in the area, based on the received (and possibly also stored) light settings d and the lighting control strategy. The occupancy behavior may for example comprise information about how often occupants (persons) 150 occupy different parts 140a-c of the area 110 (this is referred to as occupancy levels), and/or information about locations that are normally occupied (this is referred to as occupant positions). The determination of the occupancy behavior of an area is described below in relation to FIGS. 2 to 5. The method 600 may optionally comprise providing 660 information (or control parameters) P, based on the occupancy behavior, for control of, e.g., illumination of the area 110; heating, ventilation and/or air conditioning of the area 110; and/or the flow of sunlight in the area 110. The information P may be transmitted, e.g., to the lighting controller 160 or to other systems related to the area 110.

(14) Prior art methods of controlling various systems in buildings tend to use only local information available within a system. Hence, the above described way of controlling systems using relevant data from other systems (i.e. the information P) to improve performance may be advantageous compared to prior art methods. For instance, more energy efficient illumination from one lighting system may be obtained using lighting control information (e.g. the information P) from another lighting system.

(15) FIG. 2 shows a schematic top view of an office area 200 which is illuminated by the lighting system 100 of FIG. 1 (not shown in FIG. 2), and in which occupancy behavior is to be determined/estimated by the lighting control analyzer 170 of FIG. 1. It is to be noted that the area 110 shown in FIG. 1 may be a subset of the office area 200 shown in FIG. 2, and that in order for the lighting system 100 to illuminate the office area 200, it may comprise more lighting devices 120a-c and presence sensors 130a-c than shown in FIG. 1. For example, a plurality of lighting devices and presence sensors (not shown in FIG. 2) may be, e.g., evenly distributed in the office area 200.

(16) The office area 200 depicted in FIG. 2 as an example comprises a number of work stations or actual occupant positions 201-215, normally occupied by persons working in the office area 200. Occupant positions 201-215 are supposed to be located in chairs at desks distributed in the office area 200. Windows 220 are arranged along one of the walls of the office area 200 in this example.

(17) With reference to FIG. 3, an example of actual occupancy levels and occupant positions in the office area of FIG. 2 will be described. These actual occupancy levels and occupant positions are examples of occupancy behavior to be determined (or estimated) by the lighting control analyzer 170 of FIG. 1. FIG. 3 shows a schematic top view of the office area 220 of FIG. 2, with an example of actual occupancy levels and actual occupancy positions 201-215. The actual occupancy levels are indicated as regions, around each of which actual occupant positions 201-215 are shown, the regions being filled by different patterns. The different patterns indicate different values of the occupancy levels. For example, the pattern around occupant positions 212 and 214 indicates high occupancy levels, which means that the occupant positions 212 and 214 are occupied by persons more often than other occupant positions, such as e.g. occupant positions 404 and 415 surrounded by a pattern indicating low occupancy levels. It is to be noted that the occupancy levels may be measured using different scales. The scale from 0 to 1, shown in FIG. 3, is an example scale in which an occupancy level close to 1 indicates that the corresponding location is occupied during a large part of a usual working day.

(18) With reference to FIG. 4, an example of occupancy levels and occupant positions in the office area of FIG. 2, determined by the lighting control analyzer 170 of FIG. 1, will be described. These occupancy levels and occupant positions are examples of occupancy behavior and are the results of an attempt by the lighting control analyzer 170 to estimate the actual occupancy levels and occupant positions 201-215 depicted in FIG. 3. FIG. 4 shows a schematic representation of an example of occupancy levels and occupant positions 401-417 in the office area 200 of FIG. 2, determined by the lighting control analyzer 170. In the present example, the lighting controller 160 determines the light settings d using a localized illumination rendering strategy in which the dimming levels of the lighting devices are determined to provide a specified higher level (e.g., 500 lux) around occupied locations and a lower level (e.g., 300 lux) elsewhere in the office area 200.

(19) The occupancy levels and occupant positions 401-417 may be determined by the lighting control analyzer 170, based on received dimming levels d, according to the following method:

(20) Determine the combined illuminance I(x, y) provided by the lighting devices at each point (x, y) in the office area 200, based on the received dimming levels d, and compute an average illumination I.sub.av over the points in office area 200 (note that x and y axes are not represented in the drawings but may be arranged along two perpendicular walls of the office area 200).

(21) For each point (x, y) satisfying I(x, y)>I.sub.av, i.e. for which the estimated illuminance exceeds the average value, construct a circular region R(x, y) with center at (x, y) and radius r (chosen such that the region R(x, y) corresponds to a regular-sized work space, e.g., r=0.5 meters).

(22) For each region R(x, y), determine the largest illuminance I.sub.x over the points in this region and assign the point (x, y) the weight I(x, y)/I.sub.max. The weight I(x, y)/I.sub.max may be seen as a momentary occupancy level, in some sense indicative of a probability that the point (x, y), or at least its region, is currently occupied. Momentary occupancy levels of points (x, y) not satisfying I(x, y)>I.sub.av may preferably be assigned the value 0.

(23) Determine the occupancy level for each point (x, y) in the office area 200 by forming a time average of the momentary occupancy levels I(x, y)/I.sub.max determined for that point.

(24) For each point (x.sub.j, y.sub.j) in the office area at which the occupancy level has a local maximum (the maximum value is denoted by O.sub.j), define a circular region R.sub.j with center at the point (x.sub.j, y.sub.j) and radius r (note that j is an index representing an example enumeration of the points at which the local maxima are located).

(25) For each of the regions R.sub.j, determine an occupant position by forming an average over all points in the region R.sub.j with occupancy level above O.sub.j/2. The average may e.g. be computed as a linear mean, or as a position minimizing squared distances to the above mentioned points.

(26) The outline of the above method may be summarized with reference to FIG. 6. The step of determining 650 the occupancy behavior may comprise determining 651 an illumination, based on a dimming level vector received at a certain time instant. The method 600 may optionally comprise obtaining 610 a mapping (or other information needed to perform said determining 651) between light settings for the lighting devices and the illumination provided by the lighting devices. Based on knowledge of the lighting control strategy (i.e. the localized illumination rendering), a momentary estimate of occupancy levels and occupant positions is made 652 based on the provided illumination. The step of determining 650 the occupancy behavior may comprise improving the estimation of occupancy levels 653 and occupant positions 654, based on building a distribution using further values of provided illuminations corresponding to other received dimming level vectors, for example 100 different dimming vectors (i.e. occupants of the office may possibly be at different locations at the time points corresponding to every one of these).

(27) Comparing FIG. 4 with FIG. 2, it is clear that the determined occupant positions 401-417 and the surrounding determined occupancy levels are fairly accurate, i.e., correspond to the actual occupant positions 201-215 shown in FIG. 2 and the actual surrounding occupancy levels. The overestimation at a point denoted by 417, at the bottom-right corner of FIG. 4, may be a consequence of working with such limited knowledge as provided by only the dimming control values, instead of more direct information, such as input from presence sensors.

(28) With reference to FIG. 5, an example external light contribution (e.g. daylight contribution) and a light ingress location in the office area of FIG. 2, both determined by the lighting control analyzer 170 of FIG. 1, will be described. This determined external light contribution and this light ingress location are the results of an attempt by the lighting control analyzer 170 to estimate the actual external light contribution and light ingress location (windows 220) of the office area 200. FIG. 5 shows a schematic representation of daylight contribution to the illumination and a daylight ingress location (i.e. windows) 501 in the office area 200 of FIG. 2, both estimated by the lighting control analyzer 170. Assuming that the lighting controller 160 employs the localized illumination rendering strategy described above, daylight ingress locations of the area 200 may be estimated by the control analyzer 170 using the following method:

(29) For each point (x, y) in occupied regions R.sub.j, form

(30) $D^{\prime }\left(x,y\right)={\left\{200\times \frac{I\left(x,y\right)}{I_{\max }}+300-I\left(x,y\right)\right\}}^{+}$
where the operator {z}.sup.+ has value z for positive z and 0 for negative values, and I.sub.max is the maximal value of illuminances in a region R(x, y) of radius r around the point (x, y). The quantity D′(x, y) is a lower-bound daylight estimate.

(31) For points (x, y) elsewhere, form the corresponding estimate by
D′(x,y)={300−I(x,y)}.sup.+
Form time averages of the lower-bound daylight estimates and identify a region of daylight ingress as a region with many points (x, y) for which these time averages are greater than a certain threshold.

(32) The above method may be summarized with reference to FIG. 6. The step of determining 650 the occupancy behavior may comprise determining 655 an expected illumination of the area by the lighting devices, based on the determined occupancy levels/positions, i.e. 300 lux and 500 lux (scaled by I(x, y)/I.sub.max) in unoccupied and occupied locations, respectively. It may further comprise comparing 656 the expected illumination with the actually provided illumination I(x, y) and estimating 657 light ingress locations, based on such comparisons for several time instants.

(33) As shown in FIG. 5, the estimated daylight contribution is concentrated in the upper part of the office area 200 and suggests a daylight ingress location 501 along the upper wall of the office area 200. It is to be noted that the estimated daylight contribution may be measured using different scales. The scale from 0 to 1, shown in FIG. 5, is an example scale in which 1 corresponds to the highest estimated daylight contribution in FIG. 5, and 0 corresponds to no estimated daylight contribution.

(34) Knowledge of occupancy levels, spatiotemporal occupancy patterns and daylight distribution may, e.g., be used to provide improved localized heating/cooling. In particular, heating/cooling conditions may be regulated in accordance with the number of occupants in close vicinity within an area, the amount of time an area has been occupied, and the proximity to a window source (which may be treated as a source of natural heat or cold, depending on weather conditions). Further, this knowledge may be used to provide, on the one hand, improved blind control, such as, allow a larger ingress of daylight and simultaneously improve the outside view from the office when there is no occupant close to the windows. On the other hand, in some instances when occupants are present in those locations close to the windows, it would be desirable to avoid direct sunlight (glare) so the blinds could be closed.

(35) While embodiments of the invention have been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. For example, it is possible to operate the invention in an embodiment wherein the lighting control analyzer receives light settings from multiple lighting systems (comprising lighting devices and lighting controllers), or where the lighting control analyzer receives light settings for control of a single lighting device adapted to illuminate different parts of an area by e.g. moving or rotating (or by the light output of the lighting device being e.g. directed or reflected to different parts of the area).

(36) Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.