GB2389415A - Measuring the population density in defined spaces - Google Patents

Abstract

A system is provided whereby it is possible to determine the population density of an enclosed space such as an elevator 1, i.e. how full it is. An energy source 6 and an array of detectors 7 are provided, such that population density is indicated by the interruption of signals to the detectors. The energy source may be electromagnetic radiation such as infrared or ultrasonic waves. There may be an array 5 of sources 7 such that each detector has a corresponding source, with the sources being on an opposing surface to the detectors or alternatively each detector being adjacent the corresponding detector, the energy beam being reflected off the opposing surface 8. In the case of an elevator being assessed as full, a signal can be sent to prevent it stopping to pick up passengers, thus improving the efficiency of the elevator.

Description

23894 1 5

SYSTEM FOR MEASURING POPULATION DENSITY IN

DEFINED SPACES.

This invention relates to a system for measuring the density of population 5 in defined spaces, including enclosed spaces such as lifts (elevators); public transport conveyances, for example buses, trains (surface or underground) and trams; halls or other rooms in buildings; or designated spaces such as a ticketing area within a room or hall.

10 Difficulties arise in connection with the provision of access to such spaces, in that there is usually no capability of estimating, during operation, whether there is room for further occupation of the space or whether the space has already been filled to a predetermined maximum acceptable spatia; density.

In the case of lifts, for example, whilst there may well be a total payload sensor that measures the overall mass of the lift cabin and its occupants for safety purposes, this information is used only to prevent operation of the lift if the measured overall mass exceeds a predetermined maximum 20 payload. This safety provision does not address issues such as inefficiencies introduced into the running of the lift by having it stop, notionally to pick up extra passengers, who cannot board because there is physically no room for them. In these circumstances, subject to the aforementioned maximum payload being adhered to, it is not the mass, 25 but the density with which the occupants, their baggage and other transportable materials, and any conveyances such as pushchairs and

wheelchairs, are packed into the lift that determines the space available for new boarders.

It is an object of the invention to address this difficulty and, accordingly, S the invention provides a system for measuring the spatial occupation density in a defined space; the system including detector means for detecting information indicative of the amount of the space that is occupied by people and/or objects, and for producing electrical signals indicative of the detected information, means for processing the electrical 10 signals to generate a control signal indicative of the relationship of the measured spatial occupation density to a predetermined density level and for utilising the control signal to control access to the space.

Where the defined space comprises a lift cabin, Of a public transportation S conveyance, it is preferred that the system utilises the control signal to prevent the lift or conveyance from stopping to pick up potential passengers for whom there would not be space; thus improving the operational efficiency of the lift or other form of transport.

20 In such circumstances, it is further preferred that the system be configured to provide a signal to waiting passengers that explains why the lift or conveyance has not stopped to pick them up.

Preferably, the detector means has associated therewith source means for 25 emitting energy that can be received by the detector means, and to which the detector means is sensitive. By this means, special processing techniques can be applied to ensure that the processing is carried out only

in respect of detected information deriving from the energy emitted from the source, thereby rendering the system more selective and less susceptible to extraneous factors such as ambient variations and tampering. The invention may employ any convenient form of energy, such as electromagnetic radiation at infra-red, ultraviolet, optical or radio frequencies, for example; and ultrasonic radiation; and it may utilise sources and detectors or merely detectors, depending upon the form of 10 energy employed.

In one preferred embodiment of the invention, a plurality of individual beams of energy is distributed in a predetermined pattern over the space; each beam running uniquely from a particular source to a particular 15 detector. By this means, the entire space can be analysed as to the presence or absence, at each beam location, of a part of a person or object. Each source and detector pair, in such a system, may be substantially co 20 sited (for example by the detector annularly surrounding the source but being shielded from direct radiation form the source), in which case the beams are reflected from a suitable material disposed on a surface of the space which is remote from that on which the source/detector pairs are located, and such that the beams will be interrupted by the presence of 25 people and/or objects. In one example, the source/detector pairs are mounted in a ceiling and the reHectors are installed in a floor. Retro

reflectors may be used' if desired, to ensure that each beam is accurately reflected back towards its source.

In an alternative preferred arrangement, the sources and detectors are 5 separated, so that the sources are disposed, in a predetermined pattern, on one surface arid the respective detectors are disposed, in an identical pattern, on a remote surface, such that the beams will be interrupted by the presence of people and/or objects.

0 In any Everett, where beams of electromagnetic energy are employed in the formats described above, it is preferred that the sources be modulated at characteristic frequencies, to ease the task of distinguishing the energy of different beams from one another and from ambient effects, such as overall changes in light intensity and SOHz flicker associated with radiant 15 lighting. in some circumstances, it may not be necessary for all beams to have characteristic frequencies; relatively small groups of closely neighbouring beams may require different modulation frequencies but, by appropriate assignment of frequencies, that relatively small group of modulation frequencies can be re-used for all of the remaining beams.

The system may be operated in accordance with a detection-only principle, in which, for example, an overhead TV camera views the space and detects information as to the occupancy level therein. Again, the problems of variation in ambient lighting etc. may be addressed by 25 flooding the space with light modulated at a characteristic frequency, or range of frequencies, and passing output signals from the camera through circuit elements tuned to the characteristic frequency or frequencies.

In order that the invention may be clearly understood and readily carried into effect, certain embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of 5 which: Figure l shows, in schematic perspective view, certain components of a i system in accordance with one embodiment of the invention; lo Figure 2 shows, in sirrular view to Figure l, certain components of a system in accordance with an alternative embodiment of the invention; Figure 3 shows, in similar view to Figures l and 2, certain components of a system in accordance with another embodiment of the invention; Figures 4(a), 4(b) and 4(c) show respectively, and in plan view, a schematic pattern of beams, employable with the embodiments of the I invention shown in Figures 1 and 2; an imaginary occupational distribution; and the effect of that distribution upon the beams; and Figure 5 shows a typical processing arrangement for the system.

Referring now to Figure l, a lift cabin l is shown in outline; the cabin] having doors 2,3 which may, as is conventional, be controlled under the 25 influence of beams of infra-red energy, for example, directed across the doorway such as to prevent closure of the doors whilst people are entering or exiting the lift.

In accordance with this exemplary embodiment of the invention, the ceiling 4 of the lift cabin supports an array S of source/detector pairs, such as 6 and 7. The sources such as 6 can be energised so as to emit s respective beams of energy and the respective detectors such as 7 are disposed so as to receive the energy from their respective sources after reflection from reflective material located on the floor 8 of the lift cabin.

It is convenient for each detector such as 7 to be provided in annular 10 form and disposed to surround its respective source 6; suitable annular shielding being provided to shield the detector against the direct reception of energy emitted from the source. In this respect, it may be preferred in some circumstances to permit a small amount of the energy to leak directly from the source to the respective detector, to be measured 15 against a background threshold that can be automatically adjusted as

necessary to accommodate ageing of the source and/or detector.

The beams of energy emitted from the sources such as 6 are preferably collimated, to render them relatively small in diameter, thereby 20 improving the accuracy of individual beam measurements and reducing the risk that energy from one beam will erroneously be detected by a detector aligned with another beam. Collimation may also, or alternatively, be applied to the detectors such as 7.

25 The reflective material may be provided over the entire area of floor 8, but it is preferably located in discrete areas, such as 9, in the target area

of each beam. Usefully, in order to preserve the integrity of individual beams, the reflective material may include or consist of retro-reflectors.

It will be appreciated that the resolution of which the system is capable will be determined at least in part by the number of beams used, and 5 possibly also by the pattern in which they are lain out. Thus, the 3x3 pattern of relatively widely spaced beams shown in Figure l is not intended to be representative of a beam density or layout used in practice, and is shown merely by way of example to illustrate some components of the system.

Figure 2 is similar to Figure 1 and shows components of a system that is similar in all respects to that of Figure l, except that, instead of having co-sited source/detector pairs and using reflected energy, the Figure 2 embodiment employs spaced apart source/detector pairs. In the example IS shown the sources such as 16 are distributed in a predetermined pattern, or array 15 over the ceiling 14 and the respective detectors such as 17 are distributed in an identical pattern over the floor 18. All constructional and operational arrangements discussed in relation to Figure 1 apply? mutatis mutandis, to the arrangement of Figure 2.

Figure 3 shows an arrangement in which a single source 26 of a three dimensional, wide-angled beam of energy is mounted to the ceiling 24 of a lift cabin 21, and an array of detectors such as 27, responsive to the energy emitted from the source 26, is distributed over the floor 28.

25 Where a single, wide beam of energy is used, as shown in Figure 3, the demands on processing equipment attached to the detector outputs can be greater than they are in circumstances such as those described with

reference to figures l and 2, where information derived from individual beams is processed. In many situations, this is not a matter of great significance, because the amount of processing power available will be more than sufficient to accommodate such increased demands. If desired 5 or if necessary, however, the processing demands can be reduced by having the source 26 emit a smaller, scanned beam of energy that, at any time, is directed towards only one detector, or a small group of detectors, thus enabling data for processing to be sorted out on a timed basis.

Clearly, such scanning need not involve movement of the source itself.

10 Depending upon the nature of the energy emitted from the source 26, the scanning may be effected by means of a collimating or other optical component disposed in the path of the beam.

It will be appreciated that, in all of the foregoing embodiments, the 15 surfaces upon which the source(s) and detectors are mounted will be chosen to suit the layout of the enclosed space and so as to derive the required information therefrom with a requisite degree of accuracy and efficiency. Thus, in any given installation, the floor and ceiling need not be used to support the sources and detectors if, for example, it is 20 determined that better results could be obtained by mounting components to sidewalls anchor on angled surfaces specially created for such purposes. Where floor and ceiling mounted components are used, moreover, the 25 mounting of the source(s) and detectors could be inverted with respect to the arrangements shown in Figures 1 to 3. This may be preferred particularly where large reflective sheets might otherwise need to be

secured to a floor area, partly because it easier to mount sources and detectors in recesses where they can be protected from damage that could be caused by people walking on them, and partly for purposes of modesty of the lift users.

Whether the system operates with multiple discrete beams of energy (Figures 1 and 2) or with a single wide-angled beam, with or without some scanning [unction, (Figure 3), the objective is to obtain from the detectors electrical signals bearing information as to the actual lO occupation density within the lift cabin. This information is then processed to generate a control signal that can be used to control access to the lift.

Thus, in one example, the control signal is used to override a call signal, 15 placed by someone requiring access to the lift, if the information derived as described above indicates that the lift cannot accommodate another passenger, due to the nature of its current occupancy. In this respect, the system may further incorporate detecting means, external to the lift, to ascertain the number of potential passengers waiting on the call. Further 20 the system may be linked to an input derived from the floor stop selector button in the lift cabin, which indicates whether an existing passenger has requested a stop on the relevant floor.

Figure 4(a) shows, in plan view, the multiple discrete beam arrangement 25 of Figures 1 or 2, showing a typical beam density and pattern. Figure 4(b) shows, from the same view, an example of an occupancy distribution and Figure 4(c) shows, again from the same viewpoint, the

blocking effect of the occupancy distribution upon the beams of energy as detected by the detectors of the system. The information relating to the location and number of occluded beams is processed to generate the aforementioned control signal, and it will be appreciated that the system 5 provides and operates upon information that is directly indicative of the spatial distribution of people and/or objects in the lift cabin.

In any embodiment of the invention, various forms of energy may be utilised in order to achieve the desired objective. Electromagnetic 10 radiation at infra-red, ultraviolet, optical or radio frequencies, for example, may be used, as may ultrasonic radiation.

It is preferred in general to utilise infra-red or ultraviolet radiation, as such radiation is easily and inexpensively generated in the quantities 15 required for accurate measurement, and the corresponding detectors are also inexpensive, robust and reliable. It is also relatively simple to constrain such radiation accurately into relatively narrow, beam-like forms. The sources are easy to modulate, which may be required for reasons such as those discussed above, and they do not have any adverse 20 effects on users of the system. Visual light can however be used if desired, and exhibits some advantages, not least that it can be integrated with CCTV equipment.

Figure 5 shows, in block diagrammatic form, a schematic arrangement of 25 an overall system in accordance with one example of the invention.

A central processor 100, which may simultaneously receive inputs from system components in several lifts if the system is employed in a large complex, such as a hotel or some other kind of high-rise building, controls, or at least monitors, the energisation of one or more sources 106 s disposed in a lift cabin lot and processes the information produced by the detectors such as 107 in the cabin 101, to assess the actual spatial occupancy profile of the cabin 101. The information derived from the detectors such as 107 is processed in a computer 1 lO, wherein it is also formatted for comparison in a processing unit 1 l l with acceptable spatial to occupancy criteria pre-prograrnmed into a computer store 112. In the event that the comparison effected within unit 1 l 1 indicates that the spatial occupancy profile within cabin 101 is such that further passengers cannot be accommodate without breaching the criteria programmed into store l 12, the system generates a control signal on a control line l 13 to 5 override any call signal for the lift, until such time as the spatial occupancy profile within the cabinlOl has changed to an extent that it now conforms to the aforesaid criteria.

It is preferable for the control signal, or a signal derived therefrom, to be 20 applied also to local signage l 14 capable of indicating to waiting passengers that the lift cabin cannot currently accommodate them, but that they will be attended to as soon as possible.

The pre-loaded criteria can be changed locally, by authorised personnel, 25 should it be found (for example) that the system consistently underestimates load space availability, by opening locked access 115 to a local keyboard 116.

Figure 5 also shows, in dashed outline to indicate its optional nature, a modulation device 117 capable of modulating the beam emitted from the source 106 and corresponding filtering and amplification components 5 118, 119 provided to selectively process signals, derived from the detector 107, at the modulation frequency.

In general operation of the system, therefore, when the lift doors close, a direct evaluation of the spatial occupancy profile within the cabin is 10 measured by the system. Information indicative of this profile cart then be cross-referenced to calls for the lift to stop (posted externally and

internally of the cabin) to permit a decision to be made as to whether to stop the lift in response to an external call.

15 As mentioned previously, an assessment of the spatial area located by users waiting for the lift can be obtained by extra measuring devices located in the waiting areas; such extra devices being similar to those provided within the lift cabin or forming part of an existing CCTV surveillance installation, for example. At intermediate floors, it may be 20 desirable to have separate waiting areas for passengers wanting to ascend and descend, so that the two groups can be assessed separately as to their overall spatial requirements. As an alternative, it can be arranged that the lift will stop in response to a call, irrespective of how many people may be waiting, if it can accommodate at least one person.

As has been mentioned previously, the invention is not restricted in its application to usage with lifts. It can find application also in the field of

public transport and, if so used, the control signal can be relayed to a central despatch location if a conveyance has been unable to pick up passengers requiring the service so that additional services can be allocated to that route if available.

5 The invention also finds application in other circumstances where spatial loading is an important criterion on deciding whether further influx can be accommodated. In this respect, the invention may be applied in dancing or gaming establishments, galleries, exhibitions, sports events, concerts, ticketing halls etc. to ensure that permitted occupancy loadings 10 are not exceeded

Claims (1)

1. CLAIMS:

   1. A system for measuring the spatial occupation density in a defined space; the system including detector means for detecting information s indicative of the amount of the space that is occupied by people and/or objects, and for producing electrical signals indicative of the detected information, means for processing the electrical signals to generate a control signal indicative of the relationship of the measured spatial occupation density to a predetermined density level and for utilising the 10 control signal to control access to the space.

   2. A system according to claim 1 wherein the defined space comprises a lift cabin, or a public transportation conveyance, and the system includes means for utilising the control signal to prevent the lift 5 or conveyance from stopping to pick up potential passengers for whom there would not be space.

   3. A system according to claim 2 wherein the system comprises means configured to provide a signal to waiting passengers indicating 20 why the lift or conveyance has not stopped to pick them up.

   4. A system according to any preceding claim wherein the detector means has associated therewith source means for emitting energy that can be received by the detector means, and to which the detector means 25 is sensitive.

   5. A system according to any preceding claim wherein the energy is selected from the group comprising: electromagnetic radiation at infra-

   red, ultraviolet, optical or radio frequencies; and ultrasonic radiation.

   5 6. A system according to any preceding claim wherein a plurality of individual beams of energy is distributed in a predetermined pattern over the space; each beam running uniquely from a particular source to a particular detector.

   10 7. A system according to claim 6 wherein each respective source and detector pair is substantially co-sited.

   8. A system according to claim 7 wherein each detector is annular and surrounds its respective source.

   9. A system according to claim 7 or claim 8 wherein each detector is substantially shielded against the reception of radiation directly from the source. 20 10. A system according to any of claims 7 to 9 wherein the beams are reflected from a suitable reflective material disposed on a surface of the space which is remote from that on which the source/detector pairs are located, and such that the beams will be interrupted by the presence of people and/or objects.

   2s 1 1. A system according to claim 10 wherein said reflective material consists of or includes retro-reflectors.

   12. A system according to claim 6 wherein the sources and detectors are separated, the sources being disposed, in a predetermined pattern, on one surface and the respective detectors being disposed, in an identical 5 pattern, on aremote surface, such that the beams will be interrupted by the presence of people and/or objects.

   13. A system according to claim 4 or any claim dependent thereon further including means for modulating the source means at one or more 10 characteristic frequencies.

   14. A system according to any of claims 1 to 4 wherein a plurality of detector means is disposed to receive energy from a single source means.

   5 15. A system according to claim 14 further comprising means for scanning the energy from said source means relative to said detector means. 16. A system for measuring the spatial occupation density in a defined 20 space; the system being substantially as herein described with reference to and/or as shown in the accompanying drawings.