WO1997001154A1

WO1997001154A1 - A tag and tag monitoring system

Info

Publication number: WO1997001154A1
Application number: PCT/GB1996/001516
Authority: WO
Inventors: Mark Mitcheson; Robert Andrew Kevan; Mark Nicholas Grenside
Original assignee: Medestate Ltd.
Priority date: 1995-06-21
Filing date: 1996-06-21
Publication date: 1997-01-09

Abstract

A tag monitoring system and a tag for use therein is disclosed. A system is provided in which the location of tag holders can be detected in different regions within a building or other site. This is achieved by using a plurality of beacon sets each defining a domain within a monitored volume. The beacon sets can be sequentially selected to poll their domain to uniquely identify any tags within the domain and to update location data defining the location of wearers of the tags accordingly.

Description

Title of the Invention

A TAG AND TAG MONITORING SYSTEM

Field of the Invention

The present invention relates to a tag monitoring system and to a tag for use therein.

Background of the Invention

One aim of the invention is to provide a system in which the location of tag holders can be detected in different regions within a building or other site.

Summary of the Invention

According to the present invention there is provided a tag monitoring system comprising: a tag issue unit for issuing a plurality of tags, each tag being uniquely identifiable; a system controller for holding the identity of each issued tag with data identifying the location of that tag within a monitored volume; a plurality of beacon sets defining a domain within the monitored volume, the beacons within each set each having a transmit antenna and a receive antenna for transmitting and receiving respectively electromagnetic signals in the domain, wherein beacons within one set are arranged at different locations from beacons in the other sets to substantially avoid dead zones within the domain, and wherein the system controller comprises switching means for sequentially selecting said beacon sets to poll the domain to uniquely identify any tags within the domain and to update said location data accordingly.

Thus, each person to be monitored is issued with a tag which is subsequently identified when the tag wearer enters a domain. Once the presence of a tag in the domain is identified, a detection record can be created detailing the location of the wearer and the date and time at which detection was made.

Arrangement of beacon sets to avoid dead zones ensure there is full coverage in each domain. Thus, the domains do not need to be physically defined and could even cross other physical boundaries'.

In most implementations there are a plurality of domains, each domain being defined by such a plurality of beacon sets. In that event, the system controller is operable to poll all of the domain to determine the location of tags and to keep a detection record.

The monitored volume can be defined by a physical boundary having at least one exit zone, there being aranged at said exit zone an internal beacon set and an external beacon set on opposed sides of the exit zone in relation to the physical boundary to define a gate region. In that event, the system controller is operable to poll said gate region to detect when any tags leave the monitored volume.

The system controller can be arranged to generate a warning signal when a tag leaves the monitored volume.

The system controller can comprise a domain controller for polling the or each domain and a separate data concentrater for holding up-to-date information concerning the identity of each tag and its location.

The data concentrater and the domain controller can be separately connected to a network which allows communication between them. The tag issue unit may also be connected to that network. The monitored volume can include a plurality of domains, with a plurality of domain controllers, each domain controller monitoring a plurality of said domains.

Each tag issued by the tag issue unit can have stored therein a unique code identifying the tag. In that case, the system controller is operable to poll the or each domain by issuing a sequence of codes for transmission by the transmit antennas of the beacon sets and for awaiting any responses via the receive antennas of the beacon sets, a response being issued by a tag whose stored code matches the transmitted code.

The εystem controller can hold with the identification of each tag an expiry time for that tag, the expiry time representing the time at which a holder of the tag can no longer validly remain in the monitored volume and is operable to generate an expiry signal to that tag when the expiry time is reached.

Tags using electromagnetic signals can be used to monitor the locations and movements of people on a site or in a building.

The present invention provides in another aspect a tag for use in a tag monitoring system comprising: a receiver for receiving an electromagnetic signal from a system controller; a transmitter for transmitting electromagnetic signals aε response to received signals; logic circuitry for controlling the responses of the tag; and a visual indicator controlled by the logic circuitry so that it can be activated in response to electromagnetic signals transmitted from the system controller.

The visual indicator can be a light-emitting diode or other light which is turned on continuously or to flash when activated. Each tag can include a store holding a code uniquely identifying the tag and a comparator for comparing incoming codes from the system controller with the stored code, wherein a response is issued if the incoming code matches the stored code.

The present invention also provides a tag monitoring system for monitoring the locations of tags within a volume, wherein the system controller holds the identification of each tag within the monitored volume together with expiry data denoting an expiry time beyond which the holder of the tag should no longer validly remain in the monitored volume, the εystem controller being operable to issue an expiry signal to a tag when itε expiry time iε reached, εaid expiry εignal cauεing the visual indicator to be activated.

Where the tag includes a store holding a unique code, the expiry signal iε iεsued with the code uniquely identifying the tag for which the expiry time has been reached.

The system controller includes a clock so that the real time can be compared with the expiry times of tagε to iεsue the expiry signal when the expiry time for an identified tag has been reached.

Alternatively or additionally to uεing the viεual indicator to indicate expired timeε, the system controller can transmit a signal to actuate the visual indicators on all tags in an emergency situation.

For a better understanding of the present invention and to show how the same may be carried into effect reference will now be made by way of example to the accompanying drawings. Brief Deεcription of the Drawings

Figure 1 iε a block diagram of a tag monitoring εyεtem;

Figure la is a diagram of a gate zone;

Figure 2 illustrateε how a domain iε defined using beacon sets;

Figure 3 iε a diagram repreεenting how the beacon εets are activated in each domain;

Figure 4 is a block diagram of elements of a domain controller;

Figure 5 is a diagrammatic sketch indicating operation of the domain controller; and

Figure 6 iε a block diagram of the main components of a tag for use in the system.

Description of the Preferred Embodiment

Figure 1 is a block diagram of a tag monitoring system. Reference numeral 2 denotes a communication network by means of which the components of the monitoring syεtem are able to communicate. The monitoring system comprises a tag isεue unit 4 connected to a tag reader 6. The tag iεεue unit 4 is connected to the network 2. Also forming part of the monitoring system are first and second domain controllers 10,12 which are each connected to the network 2. There iε alεo a data concentrater 14 connected to the network 2 and four gate controllers 16,18,20,22 each connected to the network 2. It will be appreciated from the following description that the number of domain controllers and gate controllers can be selected according to the requirements of the monitoring syεtem. Each gate controller defines two zones indicated in Figure 1 as zone A and zone B. Those zones are separated by a physical boundary. These are illustrated only for the gate controller 22 but will be defined for each of the gate controllerε 16,18 and 20. The first domain controller 10 iε in communication with five domains labelled Domain A to Domain E respectively. The second domain controller 12 is connected to three domains labelled Domain F to Domain H. These domains are not defined by phyεical boundaries but by a scanning system described in more detail hereinafter.

Tags are iεsued at the tag isεue unit 4. Each tag includes a receiver and tranεmitter for reεpectively receiving and tranεmitting radio frequency (RF) signalε allowing the tag to communicate with the monitoring system.

An overall volume to be monitored is defined by a phyεical boundary. That boundary haε a εet of exitε/entranceε, each of which is monitored by a gate controller. Each gate controller has two separate setε of antennaε, one monitoring zone A, for example inεide the volume, and the other monitoring zone B, outεide the volume.

Figure la iε a diagram in the region of such an exit/entrance. Reference numeral 1 denotes the wall constituting the phyεical boundary defining the exit/entrance 3.

Each of the domains A to H is a sub-volume within which the main volume in which tagε may be detected. The domains are within the phyεical boundary. The domainε are defined by tag detection antennae (beaconε) diεtributed throughout the volume. The beaconε are arranged in a plurality of beacon εetε, with each εet comprising a plurality of beacons connected to be activated together. Depending on the size and nature of the domain to be defined, any number of beacon sets can be utilised. The beacon sets are arranged so that there is full coverage throughout the domain volume. Figure 2 shows a domain having two beacon sets. The first beacon set BEACON SET 1 is εhown shaded on the left hand side of Figure 2 and compriseε five beaconε whoεe area of coverage iε illuεtrated diagrammatically by the outer circumferenceε of the circles. Reference numeral 24 denotes a beacon. The diagram on the right hand side of Figure 2 represents the second beacon set BEACON SET 2 having four beacons arranged at different locations to give a different radar coverage to that given by BEACON SET 1.

The monitoring system is arranged so that it is possible to detect the location of tags within the volume covered by the monitoring system. To this end, each gate zone and domain iε polled to determine whether or not tags are in the zone or domain respectively.

For the purpoεeε of polling each domain, each domain controller has transmit and receive beacon εet controlling εwitches 26,28 illustrated diagrammatically in Figure 3. There is a εet of εuch εwitcheε for each domain to be polled by the domain controller. The transmit switch 26 haε four terminalε Tl to T4 and the receive εwitch haε four terminalε Rl to R4. Each beacon 24 conεists of a tranεmit antenna A. and a receive antenna A . The tranεmit antennaε A. of BEACON SET 1 are connected to the firεt terminal Tl of the transmit switch 26. The receive antennas A of the BEACON SET 1 are connected to terminal Rl of the receive switch 28. Similarly, the transmit antennas of BEACON SET 2 are connected to the second terminal T2 of the tranεmit εwitch 26, and transmit antennas of subsequent beacon sets are connected to the remaining terminalε T3,T4. Likewise, the receive antennas of BEACON SET 2 are connected to the second terminal R2 of the receive switch 28. The receive antennas of subsequent beacon sets are connected to the remaining receive terminals R3,R4. In operation, transmit εwitch 26 iε firεtly connected to the firεt terminal Tl and the receive εwitch 28 iε connected to its first terminal Rl. A signal is transmitted through the tranεmit antennaε A. of the first beacon set 1 and any εignals received are supplied to the receive switch 28 from the receive antennaε. The tranεmit signal is denoted T and the received signal is denoted R . Then, the transmit and receive switcheε 26,28 are connected to the εecond terminals T2,R2 and the proceεε of transmitting a signal T and waiting for any receive signal R iε repeated. Once all beacon εetε within a domain have been activated, the tranεmit and receive εwitches return to the first terminal to begin the sequence again.

As explained above, each domain controller has a plurality of setε of tranεmit and receive εwitcheε 26,28, there being one set for each domain to be polled by the domain controller. Figure 4 is a block diagram of the main components of each domain controller. The sets of transmit and receive εwitches are contained within a router 30. The router 30 haε a plurality of portε (five in the caεe of domain controller 10 and three in the caεe of domain controller 12) . These ports are denoted in Figure 4 as Pl to P5. Each port is bidirectional and iε capable of receiving and tranεmitting signals between the domains and the domain controller. The router 30 is connected via a two-way communication path to an interface 32. The interface itself communicates with a microprocessor 34. The microprocessor 34 is alεo connected to the network 2 via a two-way communication path 36. The microprocessor 34 controls polling of the domains by the domain controller.

Figure 5 is a diagram for the purposeε of explaining how the microproceεεor 34 operateε to control polling of domains. It will be appreciated that Figure 5 is diagrammatic only and that the procesεes and databaseε illustrated in Figure 5 may be organiεed in any appropriate manner within the microprocessor 34. There are a set of poll databases 40 each holding up-to-date information concerning the locations of tags isεued by the tag iεsue unit 4. There is a poll database for each domain controlled by the domain controller. Each poll database 40 holds information concerning tag IDs, the location of the tagε, the time and date. When a tag is first issued by the tag issue unit, its identity iε read by the tag reader 6, the εyεtem iε εet to mark the tag as active and its location is set to a default location, e.g. INSIDE. A tag detection process updates the poll databaseε as each domain is polled. The tag detection process 42 causeε the microproceεεor to output εignals to the router 30 to control connection of the transmit and receive switches 26,28 and generates the signals T to be transmitted. These signals are referred to herein as interrogation εignals. The interrogation signalε interrogate the domain which iε currently being polled and any reεponses received from that domain are εupplied (via the router 30 and interface 32) to the tag detection procesε. The interrogation signalε which are supplied during polling of each domain allow tags within that domain to be identified. The poll database for each domain is continuously updated during polling of that domain. A time process 44 receives data from the poll database for the domain being polled and aεcertains the following:

1) has the same tag been detected x timeε in y εecondε? (if yeε, aεεume tag entered domain) ;

2) same tag not detected x times in y εecondε? (if yeε, assume tag left domain) .

The resultε of the time proceεε 44 are uεed to update a plurality of valid detect databaseε 46, one databaεe for each domain. The valid detect databaεeε hold for each tag, the tag ID, itε location, the time and date. Againεt each entry, a flag is εet to indicate whether or not there haε been a movement of that tag since the laεt time the database was updated. Information concerning movements of tags is supplied to the data concentrater 14 via a data concentrater communication process 48. When a request is made by the data concentrater for information, the data concentrater communication process accesses the valid detect databases 46 and supplieε the information concerning any flagged movements to the data concentrater.

When tags are issued at the tag isεue unit , information is supplied to the data concentrater via the network 2 concerning the tag ID and the expiry time of that tag. That is, when the tags are used to monitor the movements of persons who have paid to enter an activity centre or the like, it is desirable to allow these persons accesε only for a predetermined period of time. The time after which they no longer are permitted to remain in the activity centre iε entered as the expiry time. The tag IDs and expiry times are held in an expiry database 50 within the domain controller. When the expiry time of a particular tag haε been reached, the identity of that tag iε εupplied to the tag detection proceεε 42 which issues an appropriate signal to the router to control subsequent transmitted signals for that tag.

The domains can be polled using one of the following techniqueε.

The tranεmitted εignal T from the domain controller includeε a meεεage which triggerε all of the tags within the domain volume. Any tagε within the volume then issue a responεe which identifieε each tag uniquely. When a plurality of tagε are preεent within the domain volumn, they iεεue reεponses in a way which prevents them from interfering with one another, i.e. on different time slotε or on different frequencieε. This requires the use of complex detection electronics within the domain controller. Aε an alternative, the εignal T tranεmitted by the domain controller can consist of a serieε of codeε, each code uniquely identifying a tag. Each tag has εtored within it a unique code which iε compared at the tag with the code transmitted by the domain controller. When the transmitted code matches the code stored within a tag, only that tag will reεpond.

The gates can be polled in a similar fashion. While a tag remains within zone A (i.e. the wearer does not pass through the exit/entrance zone 3 into zone B) , no change is made to the data stored at the data concentrater concerning the location of that tag. The data concentrater will already hold information for that tag concerning the domain inside the phyεical boundary within which the tag is located. If however a tag is detected in zone B, the gate controller will immediately notify the data concentrater via the network 2 to indicate that a wearer is now outside the physical boundary.

The data concentrater 14 thus holds up-to-date information concerning the identity of each tag which has been issued at the tag issue unit with the location of that tag. This information can be acceεεed by a file server 8 attached to the network 2 and displayed. This means that in the event of an emergency, the location of each person within the monitored volume is known. This aεεiεtε fire officerε and εafety personnel in their rescue attempts. Moreover, if there is an emergency evacuation, it is posεible to detect, using the gate controllers, that the holders of all isεued tagε have left the building.

Figure 6 is a block diagram illustrating the main components of a tag. Each tag can take the form of a watch type device to be worn on the wriεt of a wearer and has its own battery. Batterylesε tags may also be possible, activated via received εignalε. The tag comprises an RF receiver 70 for receiving transmitted signals T from the domain controller or gate controller. A diode detector 72 is connected to the RF receiver 70. Tranεiεtor circuitry 74 in the form of an emitter follower and common collecter prepare the received RF signal for εupply to a tag chip 76. The tag chip 76 includes an A/D converter 78 which receives the analogue signal from the transistor circuitry 74 and supplies a corresponding digital signal to logic circuitry 80. In the caεe where the εecond of the polling techniqueε iε uεed, the logic circuitry compareε an incoming code with a code εtored on the tag and causes a response to be isεued if there is a match between the incoming code and the εtored code. The εtored code can alεo be in bar coded or human readable form on the ouεide of the tag. The logic circuitry 80 includeε a memory for εtoring the code and a comparator for comparing the incoming code with the εtored code. The logic circuitry 80 controlε a tranεmit antenna 82 to tranεmit a suitable response signal R when the incoming code matcheε the εtored code. The tag additionally comprises a light emitting diode 84 connected to the output of the logic circuitry 80 via a resistor 86. The purpose of this light emitting diode is to provide a visual indication at each tag. The light emitting diode 84 can be activated from the domain controller by including an appropriate message in the signal T transmitted from the domain controller. In one application, a signal iε transmitted to a tag identified by its unique code when the valid time on the tag has expired, as εtored in the expiry database 50 of the domain controller. Thus, the light emitting diode will light up when the valid time for that tag has expired, thereby indicating to a supervisor that that perεon should be removed from the monitored area.

It is also posεible to use the light emitting diode in emergency situations by causing a signal to be transmitted to all tags including a message to activate the light emitting diode on each tag to render the wearers of the tagε more visible to fire personnel or the like.

The tag monitoring system described herein has applications in many different areaε where it iε required to monitor the locations of persons within a site or building, e.g. workers in hazardous environments, babies in hospitals, security and accesε control systems.

Claims

CLAIMS :

1. A tag monitoring syεtem comprising: a tag issue unit for issuing a plurality of tags, each tag being uniquely identifiable; a system controller for holding the identity of each issued tag with data identifying the location of that tag within a monitored volume; a plurality of beacon sets defining a domain within the monitored volume, the beacons within each set each having a transmit antenna and a receive antenna for transmitting and receiving respectively electromagnetic signals in the domain, wherein beacons within one εet are arranged at different locationε from beaconε in the other εetε to εubεtantially avoid dead zoneε within the domain, and wherein the εyεtem controller compriεes switching means for sequentially εelecting said beacon sets to poll the domain to uniquely identify any tags within the domain and to update said location data accordingly.

2. A tag monitoring syεtem according to claim 1 wherein there are a plurality of do ainε, each domain being defined by εuch a plurality of beacon sets and wherein the system controller is operable to poll all of the domains to determine the location of tags.

3. A tag monitoring εyεtem according to claim 1 or 2 wherein the monitored volume iε defined by a phyεical boundary having at least one exit zone, there being arranged at said exit zone an internal beacon set and an external beacon set on opposed sideε of the exit zone in relation to the physical boundary to define a gate region, the system controller being operable to poll said gate region to detect when any tagε leave the monitored volume.

4. A tag monitoring system according to any preceding claim wherein the syεtem controller comprises a domain controller for polling the or each domain and a data concentrater for holding up-to-date information concerning the identity of each tag and its location within the monitored volume.

5. A tag monitoring system according to claim 4 wherein the data concentrater and the domain controller are separately connected to a network which allowε communication between them.

6. A tag monitoring system according to claim 5 wherein the tag iεεue unit iε also connected to said network.

7. A tag monitoring system according to claim 5 or 6 wherein there is a plurality of domain controllers, each domain controller monitoring a plurality of domains.

8. A tag monitoring system according to any preceding claim wherein each tag issued by the tag issue unit has stored therein a unique code identifying the tag, and wherein the system controller is operable to poll the or each domain by isεuing a εequence of codeε for tranεmiεεion via the tranεmit antenna of the beacon εetε and for awaiting any reεponεeε via the receive antennaε of the beacon εets, a response being issued by a tag whose stored code matches a transmitted code.

9. A tag monitoring εyεtem according to any preceding claim wherein the εyεtem controller holds with the identification of each tag an expiry time for that tag, the expiry time repreεenting the time at which a holder of the tag can no longer validly remain in the monitored volume and is operable to generate an expiry signal to that tag when the expiry time is reached.

10. A tag monitoring εyεtem according to claim 9 wherein the expiry signal activates a visual indicator on the identified tag.

11. A tag for use in a tag monitoring system comprising: a receiver for receiving an electromagnetic signal from a system controller; a transmitter for transmitting electromagnetic εignals as response to received signals; logic circuitry for controlling the responseε of the tag; and a viεual indicator controlled by the logic circuitry εo that it can be activated in reεponεe to electromagnetic signals transmitted from the system controller.

12. The tag according to claim 11 which includes a store holding a code uniquely identifying the tag and a comparator for comparing incoming codes from the system controller with said stored code, wherein a reεponεe iε issued if the incoming code matches the stored code.

13. A tag monitoring εyεtem for monitoring the locationε of tagε within a volume, the tagε being in accordance with claim 11 or 12, wherein the system controller holds the identification of each tag within the monitored volume together with expiry data denoting an expiry time beyond which the holder of the tag should no longer validly remain in the monitored volume, the εystem controller being operable to issue an expiry signal to a tag when its expiry time is reached, εaid expiry εignal cauεing the visual indicator to be activated.

14. A tag monitoring system according to claim 13 when used with tags according to claim 12, wherein the expiry εignal is issued with the code uniquely identifying the tag for which the expiry time has been reached.

15. A tag monitoring system according to claim 13 or 14 wherein the system controller is operable to transmit a signal to actuate the visual indicators on all tags in an emergency situation.