GB2405512A

GB2405512A - Apparatus For Monitoring The Position Of People And Objects

Info

Publication number: GB2405512A
Application number: GB0417921A
Authority: GB
Inventors: Paul John Smeaton
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-08-28
Filing date: 2004-08-12
Publication date: 2005-03-02
Anticipated expiration: 2024-08-12
Also published as: GB2405512B; GB0417921D0

Abstract

A portable apparatus for continuously monitoring person(s) or object(s) within a defined area comprises a guardian unit able to transmit and receive signals, receiving units which can send and receive signals to / from the guardian unit and an aerial. The guardian unit can define a permitted area within which each person or object can move. If a person or object leaves its permitted area, the guardian unit warns the user that this has occurred. The aerial on the guardian unit is capable of permitting the guardian unit to determine the direction and distance to the person or object. This information is displayed on the guardian unit using polar co-ordinates. The guardian unit can also define a zone within the permitted area so that when the person or object crosses this zone boundary, a warning is sent to the guardian unit. The guardian unit may communicate with an additional guardian unit used to monitor the same person(s) or object(s). The system is particularly suited for the monitoring of children.

Description

24055 1 2

APPARATUS AND METHOD FOR MONITORING THE POSITION OF

PEOPLE AND OBJECTS

This specification relates to the positional monitoring of people or objects. It is especially relevant to monitoring children in an area and locating a child who strays out of the permitted area.

It is known for elderly people to carry an electronic unit, which can be activated by the elderly person in the event that he / she falls, or becomes lost, etc. This is shown in Fig. 1 (Prior Art), where such a person 2 activates the unit 3 to signal 4 receiver 1 to advise a supervisor 5, via means 6, of the problem. Via a code in signal 4, the means 6 identifies who person 2 is. Similarly, receiver 1 can identify the direction from which signal 4 was received. Some receivers 1 are able to detect both direction and distance of person 2 from receiver 1. In other cases, two receivers 1 could determine the exact position of person 2 by triangulation. In yet a third case, the position of person 2 can be determined by the Global Positioning System (GPS). A variation of this system operates in people's homes, via the telephone system. It will be noted that all these systems are 'active'. i. e. the bearer must do something to cause them to work, e.g. press a button. If the fall renders the bearer unconscious, the means 4, 5 and 6 of providing assistance will not be activated until the bearer regains consciousness and presses button 3 or a passer-by finds them.

All such systems rely on a fixed receiver 1 and associated equipment 6 and are ideal for monitoring people in the limited confines of, say, a residential home. However, this type of system is not suitable for monitoring people, e.g. children, who might get lost or stray into potential danger. Children are always getting lost in crowds or when they get so engrossed in their play that they don't realise how far they have strayed from the starting point. There are two key reasons why the presently available equipment is unsuitable. One is that It does not monitor continuously the position(s) of the child / children or keep a record of their movements, so that the guardian can be alerted as the child reaches a sufficiently remote distance for the guardian to show concern. The second is that receiver 1 and associated equipment 6 is not portable, e.g. to allow the guardian to follow the children, for example, on a walk in the countryside.

It is known to use GPS technology to identify a person's position to within a radius of about 1 em and, by computing the Cartesian latitude and longitude co-ordinates, to plot this location electronically onto a map on a display screen. If a number of people are each provided with this type of apparatus, each can see their own position and that of each of the others so that their relative locations, as they all move about, can be determined at any given time. Such apparatus is ideal for, say, an elite squad of military personnel carrying out a covert operation. However, to provide a sufficiently large screen to display the map, and provide the necessary memory and computing and battery power requires a physically large and heavy unit totally unsuited to being carried by small children. It would also be far too expensive for general use.

GPS satellites are in geostationary orbit and each continuously transmits a unique reference signal. By the time these signals reach ground level, they are incredibly weak and require exceptionally sensitive apparatus to receive and process them. To identify a position accurately, signals from at least three (and preferably four) GPS satellites are needed and then the triangulated position is accurate only to about 10m. For very young children, limited to a play area of, say, 20m radius, this is not accurate enough.

Furthermore, as the signals are so weak, directional aerials are preferred. If the aerial is aligned for a broach attached to clothing when the child is standing vertically, it will be at 90 to the preferred direction when the child is lying down. If the child is lying on his / her front and the signal has to pass through the body, one or more signals may be lost and so the system will not function. Thus, a system based on GPS positioning cannot be relied upon for this application.

Thus, there is a need for a completely mobile system able continuously to monitor the position(s) of a person(s) within a defined area and to warn the guardian when the / a person is nearing, or leaving, the defined area. Ideally, when the person has left the area, the system can then be used to locate the errant person, so that they may be resumed to the defined area. This would, in effect, be a 'passive' system continuously monitoring the position(s) of person(s) and advising the guardian without the person(s) intervention.

According to the invention, there is provided a portable apparatus by which a guardian can monitor continuously the location of a person(s) or an object(s) within a defined area, comprising: i) a guardian unit having an aerial, able to transmit a signal to a receiving unit, and able to receive signals transmitted from the receiving unit; ii) a lightweight, unobtrusive receiving unit, (each) having a unique electronic identification and adapted to be worn by the person(s) or attached to the object(s), and able both to receive a signal from the guardian unit and to transmit an acknowledgement signal back to the guardian unit; iii) means, within the guardian unit, to define the permitted area and its boundary within which the person or object may move; iv) discrimination means, within the guardian unit, to analyse the acknowledgement signal and to detect when the / a person(s) or object(s) has crossed the boundary and left the permitted area and identify that person or object from its electronic 1 5 identification; v) warning means in / on the guardian unit to warn the guardian that no acknowledgement signal has been received from the receiving unit and / or that the / a person(s) or object(s) has crossed the boundary and left the permitted area; vi) a directional means on the aerial, within the guardian unit, able to indicate the direction of the person(s) or object(s) outside the permitted area from the guardian unit; and vii) a display means on the guardian unit having a first mode of operation in which the spatial distribution of the current location(s) of (all) the person(s) or object(s) is displayed using polar co-ordinates and a second m. ode of operation in which the direction from the guardian unit to that person or object that has crossed the boundary and left the permitted area is displayed; characterized in that the guardian unit communicates at regularly timed intervals with the receiving unit and receives acknowledgements from the receiving unit to confirm both that the apparatus is working normally and that the person or object is within the permitted area but, when the apparatus detects a fault and / or the / a person or object leaves the permitted area, the guardian unit recognises the fact, warns the guardian of the occurrence and allows the guardian to determine the direction in which to proceed to find the errant person or object.

According to a first variation of the apparatus of the invention, the guardian unit is enclosed in a case, with the aerial at one end and adapted to be held in a hand and / or carried in a suitable pocket / holder.

According to a second variation of the apparatus of the invention, the display means on the guardian unit indicates the relative direction(s) and distance(s) of the person(s) or object(s) from the guardian unit.

According to a third variation of the apparatus of the invention, the receiving unit is incorporated into a decorative or functional item, which a person may wear so that it does not affect their movements or actions or can be attached unobtrusively to an object According to a fourth variation of the apparatus of the invention, the decorative or functional item is a badge, or broach worn by the person or attached to the object. i According to a fifth variation of the apparatus of the invention, the decorative or functional i item is a watch or wristband.

According to a sixth variation of the apparatus of the invention, the guardian unit is provided with means to determine the permitted area. i According to a seventh variation of the apparatus of the invention, the guardian unit is provided with means to define a zone within the permitted area.

According to an eighth variation of the apparatus of the invention, the permitted area and zone within the permitted area are defined as a radial distance(s) from the guardian unit.

According to a ninth variation of the apparatus of the invention, particular radial distances are set for the / each individual person or object for the permitted area and zone within the I permitted area.

According to a tenth variation of the apparatus of the invention, the guardian unit is provided with means to assess the radial distance of the receiving unit from the guardian unit and also with discrimination means to identify when the receiving unit is at a distance greater than that defined by either the zone within the permitted area or the permitted area itself and to operate the warning means when the discrimination means determines that one / both of the permitted distances has / have been exceeded.

According to an eleventh variation of the apparatus of the invention, the warning means is audible in nature.

According to a twelfth variation of the apparatus of the invention, the warning means is visible in nature.

According to a thirteenth variation of the apparatus of the invention, the warning means is vibratory in nature.

According to a fourteenth variation of the apparatus of the invention, the visible warning is flashing on the display means indicating which of a plurality of receiving units is outside the zone within the permitted area or outside the permitted area itself.

According to a fifteenth variation of the apparatus of the invention, when the discrimination i means in the guardian unit detects a receiving unit outside the zone within the permitted area or outside the permitted area itself it operates the guardian warning unit and also causes a special signal to be sent to the receiving unit, which causes the receiving unit to emit either a warning audible or visible to the wearer or a vibration detectable by the 1 5 wearer.

According to a sixteenth variation of the apparatus of the invention, a first audible, visible or vibratory warning is produced by the guardian unit and by the receiving unit when the person wearing, or the object carrying, the receiving unit leaves the zone within the permitted area.

According to a seventeenth variation of the apparatus of the invention, a second audible, visible or vibratory warning is produced by the guardian unit and by the receiving unit when the person wearing, or the object carrying, the receiving unit leaves the permitted area.

According to an eighteenth variation of the apparatus of the invention, the guardian unit is I provided with a second mode of operation wherein the aerial is provided with enhanced directional array capabilities to identify more accurately the direction of the errant person / object from the guardian unit.

According to a nineteenth variation of the apparatus of the invention, when the guardian unit is in the second mode of operation, the display means indicates visually the direction of the errant person / object from the guardian unit.

According to a twentieth variation of the apparatus of the invention, when the guardian unit is in the second mode of operation, the direction to the errant person / object is indicated audibly, visibly or via a vibration.

According to a twenty first variation of the apparatus of the invention, when the guardian unit is in the second mode of operation, the direction to the errant person / object is indicated by a number of different audible or vibratory outputs so that essentially the exact direction to the errant person / object can be identified without visual reference to the display means.

According to a twenty second variation of the apparatus of the invention, the guardian unit is provided with means to call the / some of / all person(s) / object(s) being monitored via audible, visible or vibratory means through their receiving units.

According to a twenty third variation of the apparatus of the invention, the display means on the guardian unit is a display screen and the means to call the / some of / all person(s) / object(s) being monitored is by touching a part / all of the screen.

According to a twenty fourth variation of the apparatus of the invention, the guardian unit is connectable to another computing means having a larger display means so that the spatial distribution of the persons or objects being monitored can be determined in greater detail, including the exact location of each person or object.

According to a twenty fifth variation of the apparatus of the invention, the guardian unit has means to record the spatial distribution of the person(s) or object(s) over a given time period so that the movement of a particular person or object over that time period can be determined.

According to a twenty sixth variation of the apparatus of the invention, a first guardian unit is provided with means to communicate with a second guardian unit so that, when a person / object leaves the permitted area the guardian in the most appropriate position can use their guardian unit, in its second mode of operation, to find and retrieve the errant person / object while the other guardian unit continues to monitor the other person(s) / object(s) within the permitted area.

According to a twenty seventh variation of the apparatus of the invention, the guardian unit continuously monitors the location of a plurality of persons or objects, each person or object having a receiving unit with its own unique identification so that the guardian unit can determine which of the plurality of persons or objects is inside the zone within the permitted area, leaving the zone within the permitted area or leaving the permitted area itself.

According to a twenty eighth variation of the apparatus of the invention, the guardian unit is preprogrammed with the unique identifications of the each one of the plurality of receiving units.

According to a twenty ninth variation of the apparatus of the invention, the guardian unit has means to program the unique identifications of each one of the plurality of receiving units into its memory.

According to a thirtieth variation of the apparatus of the invention, the guardian unit has means to recognise, which one of the plurality of receiving units identified in its memory is to be monitored at any particular time.

According to a thirty first variation of the apparatus of the invention, the guardian unit has means to add an additional receiving unit to the plurality of receiving units already identified in its memory and to be monitored at that particular time.

According to a thirty second variation of the apparatus of the invention, the guardian unit has means to delete a receiving unit from the plurality of receiving units already identified in its memory and to be monitored at that particular time.

According to a thirty third variation of the apparatus of the invention, the guardian unit has means to communicate with a selected receiving unit or some of or all of the receiving units to cause the receiving unit(s) to emit an audible, visual or vibratory warning to the wearer / person with the object.

According to a thirty fourth variation of the apparatus of the invention, the receiving unit has a means to transmit an emergency signal back to the guardian unit to cause the guardian unit to emit a particular audible, visual or vibratory warning to alert the guardian that the person / object / one of the plurality of persons / objects being monitored was in danger and required immediate assistance.

According to a thirty fifth variation of the apparatus of the invention, anti-abduction features are incorporated into the receiving units. According to a thirty sixth variation of the apparatus of the invention, the guardian and receiving units have individual power sources, which are replaceable, or rechargeable..

According to a thirty seventh variation of the apparatus of the invention, the guardian has means to recognise the presence of a prohibited person wearing a receiving unit approaching, or within, the permitted area and alerting the guardian audibly and / or visually and / or by vibratory means and / or by a text message on the display screen.

According to a thirty eighth variation of the apparatus of the invention, the guardian unit is incorporated into a mobile telephone or other appropriate electronic device.

In a preferred application of the invention, a guardian is required to care for a group of children. Each child is provided with a receiving unit, e.g. in the form of a broach, badge or wrist band, having its own unique electronic identification (ID), and each is programmed into the guardian's guardian unit. The permitted area in which the children, or each child, may play is defined and programmed into the guardian unit. The guardian would explain, and preferably demonstrate, all the particular warning signals, which each of the receiving units could emit.

The children would then be allowed to go and play but, if one approached the edge of the permitted area, i.e. crossed a zone within the permitted area, a first audible warning would alert them to this fact. This audible warning could be a 'beep', repeated if necessary, or a pre-recorded voice waming.

If the child did not return but actually crossed the boundary of the permitted area, the guardian unit would cause the child's receiving unit to emit a second audible warning ('beep' or voice) and also alert the guardian, via audible and / or visual warnings on the guardian unit. If the child did not immediately return to within the permitted area, the guardian would programme the guardian unit into its second mode of operation so that a directional array could identify the direction to the errant child, allowing the guardian, or an assistant with a second guardian unit, to go in this direction and retrieve the missing child.

Once the child had been retrieved, he / she would be escorted back to the permitted area and the guardian unit reverted to its first monitoring mode. Thus particular errant child At the end of the permitted play time, the guardian would operate a control on the guardian unit to cause signals to be sent to all the receiving units, causing them to emit a third audible warning, calling all children back to the rendezvous point. This would normally be a central point where the guardian would wait. If the guardian had to leave this point to retrieve an errant child, the guardian unit could be programmed to alert all the other children to this fact via their receiving units, e.g. by a pre-recorded voice message.

Altematively, if there was more that one guardian, each having a guardian unit, the guardians could communicate with each other, via their units, e. g. by text messages, and the most appropriately located guardian delegated to seek the errant child.

Control means on the guardian unit would allow additional children, with their receiving units, to be added to the group being monitored. Similarly, a child could be removed from the group being monitored. There would also be a facility to call a selected child back to the rendezvous point, e.g. if a parent wished to take their child to a separate location. The receiving units would ideally be fitted with a panic button, allowing the child to operate it in the event that they were being abducted, or in serious danger.

For deaf children, a vibrating effect could be provided; this would have to be in the watch / wrist band option and in contact with the skin. Guardian units may also be provided with visual and / or vibratory response features so that a deaf guardian could monitor a group of deaf children and search for errant children. In the mode to search for an errant child, the intensity of the vibration would increase as the unit was pointed more accurately in the correct direction.

The guardian unit would have a display screen able, in a first mode, to show the spatial distribution of the children within the permitted area and, in a second mode, to indicate, more accurately, the angular direction and distance to the errant child. In the first mode, an individual child or a group of children could be contacted by touching the appropriate parts of the screen. This would cause the guardian unit to send a message to the child / all the children in the group.

A further aspect of the invention is to record the spatial distribution at regular timed intervals and retain this for a period of time, e.g. like the 'black boxes' in aircraft, so that the build up to an incident could be available for future examination.

A further aspect of the invention is that the guardian units could be programmed with the IDs of electronically tagged pedophiles on the national Sex Offenders' Register. If one of these individuals approached the permitted area, the guardian unit could detect this and warn the guardian.

In addition to monitoring people, the invention could be used to monitor animals, e.g. race horses exercising in a training area and at potential risk of abduction. Similarly, the principle of the invention could used to monitor high value items, which are loaned, or hired out, e.g. audio guides at visitor attractions. Here, the audible voice warnings would be to the user of the item.

For a clearer understanding of the invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 is a diagrammatic representation for monitoring a person from a fixed location

(prior art);

Figure 2 is a diagrammatic representation of the principle of the invention showing a person being monitored by a guardian; Figure 3 is a diagrammatic representation of the principle of the invention with a guardian monitoring the spatial distribution (positions) of five people within a permitted area; Figure 4 is a diagrammatic representation of the guardian unit of the invention showing the locations of the four people being monitored relative to the position of the guardian 19; Figure 5 is a diagrammatic representation of the guardian unit of the invention with the screen in the mode for locating a person who has left the permitted area; Figure 6 is a diagrammatic representation of the display screen, showing the location of an errant child outside the permitted area; and Figure 7 is a diagrammatic representation of the display screen of a second guardian unit showing the location of an errant child.

In the following description, the same reference numeral is used for the same component or for different components fulfilling an identical role.

Referring to Figure 2, a guardian 8 carries a guardian unit 9, which transmits signals 11A to the receiving unit 10 worn by a person 7. On receipt of signal 11A, receiving unit 10 returns an acknowledging signal 11 B to guardian unit 9. On receipt of signal 11 B. guardian unit 9 is programmed to note the nomnal response. The electronics in guardian unit 9 allow many signals 11A to be made per second, each one producing the response 11 B so that contact with person 7 is effectively continuous. In a real situation, a single guardian 8 may be responsible for a number of persons 7, e.g. a schoolteacher minding a group of children on an outing.

In such a case, each child would carry a receiving unit 10. This might be a brooch or badge attached to their clothing, or possibly a unit, like a watch, strapped to a wrist. Each receiving unit 10 would have a unique ID, which could be identified by guardian unit 9. In its normal mode of operation, guardian unit 9 would be programmed to recognise the IDs of each of the receiving units 10 being monitored and each would be signaled 11A in rotation and the acknowledgement 11 B noted by the electronic circuitry.

It is important that receiving unit 10 is small, lightweight and unobtrusive so that it does not I impede the child's activities. Children tend to be fussy and will not want to carry heavy or bulky items, e.g. the units required to communicate with GPS satellites. Similarly, the aerials in receiving units 10 must be omnidirectional, as children may be standing, crouching or lying, with receiving units 10 at any angle of orientation.

Radio frequencies (RFs) are preferred for these direct transmissions forwards and backwards between guardian unit(s) 9 and receiving unit(s) 10 as they can penetrate and pass round obstructions. RFs are ideal for short range, low power applications, e.g. up to about 500m. With other short wave transmissions, e.g. to / from satellites, the receiving aerial should point directly at the transmitting aerial; this would seldom be the case with children in dynamic play. I Thus, in the normal mode of operation, signals 1 1A would be sent to each receiving unit 10 1 and acknowledged 11 B several times per second, i.e. to maintain effectively continuous; monitoring of each and every child. If no acknowledgement signal 11 B was received, I guardian unit 9 would sound an alarm and indicate the last known position of that child, e.g. by flashing on the display (see below). Guardian 8 would immediately go to the position indicated to investigate, as will be described below.

Before allowing the children, e.g. 7, going off to play, guardian 8 would instruct them about the limits within which they must remain. This could be a 50m radius in a country park or 1 Om in a city environment or other crowded area. The radius limit 1 3A of the permitted area 13 would be programmed into the guardian unit 9. Each child could have its own permitted radius, e.g. very young children limited to 20m, slightly older children to 30m and the oldest children to 50m. Fig. 3 indicates a plan view of an area with guardian 8 at the centre 19 of a permitted circle 13. In this example, five children, designated A, B. C, D and E are shown with their relevant dispositions from central point 19. (The children are designated by letters to avoid confusion with the reference numbers used for other items.) The aerial in use here would have omnidirectional capabilities and be able to indicate who was where. 1 1

Polar co-ordinates are used to define the angular direction and distances to each child A-E (Fig. 3). This simplifies the computations within guardian unit 9 as the guardian 8 automatically becomes the centre 19 of the circles defining the permitted areas 12 and 13.

A polar co-ordinate defines the angle, relative to a fixed direction, and the distance from a fixed point. Here, the position 19 of guardian unit 9 is the fixed point and the fixed direction is the axis through guardian unit 9, as shown by chain dashed line 23 (Figs. 3 and 5).

A key advantage of this means of spatial definition is that, as the guardian 8 turns round holding the guardian unit 9 in front of him / her, the display immediately changes according to the new orientation of line 23, i.e. it is automatically aligned with the direction in which guardian unit 9 is pointing and in which guardian 8 is looking. If Cartesian coordinates, e.g. latitude and longitude, were used, these would be based on a fixed point and direction, e.g. the origin of a map and north, and have to be converted to the particular geographical location where the children were being monitored. This would require a great deal more computing power, particularly when the guardian 8 fumed around, i.e. when datum line 23 moved. The result would be a larger, heavier, more costly and more complex guardian unit 9.

Fig. 4 shows one possible representation of guardian unit 9 consisting of a case 15, a display screen 16, programming buttons 17 and control buttons 18. The display on screen 16 shows the distribution of children A- Erelative to the position 19 of guardian unit 9, i.e. as shown in Fig. 3. Programming buttons 17 are designated A to I but could be numerical.

Knowledge of the spatial distribution of children A - E is useful for guardian 8, as it can indicate a child E heading for the boundary 13 of the permitted area or an unusual grouping of children, e.g. possibly bullying another child. The rate of movement of dot E, or build up of a group, will be apparent from watching screen 16 over a period of time.

By measuring the properties of return signal 11 B. guardian unit 9 can estimate how far away receiving unit 10 is. When a child leaves the permitted area 13, return signal 11 B indicates to guardian unit 9 that this child, e.g. E, has crossed boundary 13. Discrimination means in guardian unit 9 detects this and a warning is produced by guardian unit 9. This would preferably be an audible warning, via a speaker (not shown) but may also include flashing of the dot or letter E, to indicate which child had transgressed boundary 13 and the direction in which the child had gone. Guardian unit 9 would initially cause receiving unit 1 OF to emit a warning noise or voice message to alert child E and instruct" him / her to return to within the permitted area. If child E did promptly return, the warnings would be cancelled.

If Child E did not immediately return, guardian 8 would then switch unit 9, via a suitable programming button 18, into the 'search' mode (Fig. 5). This would engage a more highly directional aerial array. As guardian 8 turned towards the direction of errant child E, a line 21 would appear on screen 16 from the point 19 (representing the location of guardian unit 9) in the direction of errant child E. Lines 20 indicate the angle over which the directional array can search and guardian 8 must turn unit 9 until line 21 is visible. Knowing the approximate direction of child E from the first display (Fig. 4), the exact direction 21 (Fig. 5) can soon be found to direct guardian 8 towards errant child E and return him / her to the permitted area 13. By responding as soon as the child had left the permitted area, child E could be returned before he / she had got significantly lost and might require the services of the rescue personnel.

It will be noted that, as guardian 8 moves towards errant child E, line 21 will always point in the correct direction, irrespective of whether child E is moving or remaining still. As guardian 8 gets nearer to child E, the area between lines 20 and child E will decrease, thus focusing the search until child E if found.

The maximum transmission distance of units 9 and 10 is shown 14 (Fig. 3) and is a radius 14A well in excess of that 13 permitted to the children being monitored. By responding promptly to an errant child, guardian 8 should be able to rescue him / her without the other children being out of range 14 during the rescue period. If a receiving unit 10 fails, or otherwise ceases to send acknowledgement signals, this should be treated as if the child had left the permitted area with guardian 8 investigating immediately. In such a case, the guardian unit 9 would indicate the last known location of the child, i.e. within a fraction of a second of the failure occurring.

In a real situation, with many more than just the five children A-E shown in Fig. 5, there might be more than one guardian 19 present. Also shown on Fig. 5, is a first guardian 8 at the rendezvous point 19 and a second and third guardians 19A and 19B, indicated by a circle round a cross, with roving mandates to move among the children. In the event that child E leaves the permitted area 13 and did not respond to 'retum'calls, first guardian 19 would change his screen 16 to show a larger area (Fig. 6), i. e. including area outside the permitted area 13, indicated by the dashed circle. Clearly, if he / she went after child E, there would be no one at the rendezvous point, so first guardian 19 would send, or relay, a signal, e.g. a text message or pre-programmed alert, to second guardian, e.g. 19A, alerting him / her to the situation. The screen 16 on second guardian unit 9A (Fig. 7) would show the problem, e.g. by flashing letter E. Second guardian 19A would change his / her handset 9A to the search mode (Fig. 5) and set off in pursuit.

In a real, searching situation, e.g. among crowds of people or over rough ground, guardian 1 9A would want to look where he / she was going and not have to focus on screen 16 for longer than was absolutely necessary. An optional feature would be for unit 9A in the search mode to indicate audibly whether line 21 (to child E) was to the right or left of the centre line 23. For example, a high pitched beep could indicate that child E was to the left (as shown, Fig. 5) and a low pitched beep would indicate that the child was to the right.

Double, medium pitched beeps would indicate the direct line. The advantage of this is that it would help guardian 1 9A to look for and recognise known child E in the crowd.

It will be noted that screen 16 in Fig. 4 shows the individual letters AE of the children but on the larger area view Fig. 6, only dots are shown. In a real situation, where, say, two teachers 19 and 19A were in charge of, perhaps 50 children, these could be shown only as dots, indicating the general spatial distribution. Only the locations of the two teachers 19 and 19A would be identifiable.

If a number of children were nearing a potential danger, e.g. a road or river, they would appear only as a mass of dots on the screen. It would be possible to send a group message to them all by touching the relevant part of the screen and pressing the appropriate control key 18. Touch screen technology is well known and a finger, a fingernail or a hand held pointer could be used to touch the appropriate area; H a pointer was used either the group could be circled or it could be rubbed over the area covered by the group of dots on the screen. Another application of touch screen technology could be where, say, three teachers were minding the children, i.e. one 19 at the rendezvous point and two others, e.g. 1 9A and 1 9B roving about. If child E left the permitted area 13, teacher 19 could touch the symbol for the nearest teacher, e.g. 1 9A, and signal them to go in pursuit, while leaving the other 19B still roving about, e. g. to deter bullying.

Thus, the apparatus of the invention allows continuous spatial monitoring of a few or a large number of children, indicates when one or more is approaching the limit of the pemmitted area, allows messages to be sent to an individual, a group or the whole party.

Finally, if a child(ren) leave(s) the area, a pursuer can be delegated to go off in pursuit using either visual or audible guidance.

Prompt use of the apparatus of the invention in the manner described, would enable many potentially missing children to be retrieved quickly before they started to panic and perhaps got into serious danger. If the child was being abducted or in serious danger, he / she could press a button (not shown) on the receiving unit 10 to transmit 1 1 B a panic signal to guardian unit 9. This would cause a panic alarm to sound on guardian unit 9 for guardian 8 / 19 to take immediate action. Thus, the apparatus of the invention makes a considerable contribution to protecting children, as well as saving unnecessary calls out to the rescue services.

Clearly, a person, with serious intentions of abducting a child, might be aware of the apparatus of the invention and would attempt to stop the child pressing the panic button (not shown). They might then remove receiving unit 10 from the child and, say, leave it in the permitted area and abduct the child. It would be possible to provide precautions against such actions, e.g. an alarm to guardian unit 10 if the badge / broach was unclipped or the wrist band undone or cut; in this case, breaking an electrical connection could be the trigger. A temperature sensor in contact with the skin, which would recognise the drop in temperature, after the wrist band had been removed is another option. Altematively, a movement detector could be provided in receiving units 10 to alarm guardian unit 9 if no movement had occurred for, say, five minutes. This would have disadvantages as it would give the abductors five minutes start or it could alamm if a child went to sleep.

A variation of the system is shown in Fig. 3 whereby a reduced radius zone 12 is programmed into guardian unit 9. In this case, when a child, e. g. D, crosses line 12, i.e. is more than a distance 12A from the guardian 8, a first particular signal 11A is sent from the guardian unit 9 to receiving unit 1 OD, causing it to emit a first audible waming. On hearing this, child D should realise that he / she was nearing the edge of the permitted area 13 and return towards guardian 8. If child D did not return, the first audible signal from receiving unit 10 could be repeated. If child D still did not respond and crossed boundary 13, guardian unit 9 would send a second particular signal 11A to receiving unit 10D, causing it to emit a second audible warning and alert guardian 8, as described above.

In an actual situation, guardian 8 would assemble a group of children A E, and give each a receiving unit 10 in the form of a badge, broach or wristband, etc. and program 17, 18 each into guardian unit 9. Altematively, the receiving units 10 might all be already programmed into guardian unit 9 and it would be necessary to identify which ones were being used at that particular time and by which children. Guardian 8 would explain the limits within which the children could play and demonstrate the various warning noises, e.g. approaching the edge of the permitted zone 12 First waming), actually leaving the permitted area 13 (second warning). The children would be told to return to the rendezvous point 19 immediately this second warning noise sounded. Different children could have different radial limits within which they were allowed to play. These limits could also be defined by identifying particular geographical features of the area.

The return to the rendezvous point would also be explained and the special recall signal demonstrated. The children would then be allowed to go and play with guardian unit 9 in the monitoring mode (Fig. 4). This would show which children were where using the omnidirectional aerial.

Receiving units 10 may already be pre-programmed, or it may be possible to program each one via keys 17. Having programmed guardian unit 9, any individual child may be summoned by pressing its particular code key(s) and calling it to the rendezvous point.

This would be useful if, say, the parent arrived and wished to take the child elsewhere. As this child had left the group, its ID would be deleted from guardian unit 9 via keys 17, 18.

Similarly, if a new child joined the group, he / she would be given a badge and the ID added via keys 17,18. At the end of the play period, use of a control key 18 would recall all the children back to the rendezvous point.

In the monitoring mode (Fig. 4), guardian 8 can identify the distribution of children and summon any who are either nearing the limit of the permitted area 13 or perhaps in an area of potential danger. The search facility (Fig. 5), allows guardian 8 to identify the exact direction, within an angle 20 in which to go and retrieve an errant child who has crossed permitted area 13.

Guardian unit 9 would have a means to monitor the state of the batteries in receiving units and, if one was detected as having low charge, alerting guardian 8 so that the particular child with the suspect receiving unit 10 could be summoned to guardian 8 and have unit 10 replaced. Guardian unit 9 and receiving units 10 may be recharged by conventional means when not in use but photovoltaic means (e.g. solar cells) may be used to maintain the charge while actually in use In the event that a child is being abducted, or in serious danger, he / she could operate the panic button (not shown) on receiving unit 10 to call for help. This would cause an audible I warning on guardian unit 10 and indicate which child was in trouble, e.g. by flashing the particular ID letter, or dot, on screen 16 (Fig. 4), and the relevant direction, allowing an immediate response. To emphasise that the child was in distress, a facility could be provided suppressing the letters or dots representing all other children and just showing the positions of the child in distress (flashing) and of other guardians, 1 9A and 1 9B.

The apparatus of the invention could be incorporated into a mobile phone or other appropriate, portable electronic unit. In either case, the basic principle would add greatly to the security of groups of children and to the piece of mind of their parents.

One basic application of the invention has been taught, but many others are available, and will be apparent to the skilled man, all falling within the scope of the invention. The following indicates some of these other applications: 1. A chaperone minding a disturbed child, i.e. a one-to-one monitoring; 2. A mother minding her children, i.e. one person minding a small group (say 2 - 6); 3. A child mincer(s) / teacher(s) minding a larger group of children; i.e. one / two I people minding a medium-sized group (say 10 - 30); 4. A teacher(s) monitoring a school playground at playtime; i.e. one / more teacher(s) monitoring a large group (say 50 200); I 5. A hospital ward / maternity ward / care home; i.e. a person monitoring a group of high risk people, e.g. mental patients, babies or frail / Alzheimer's people; ; 6. A Leader monitoring a group of fell walkers, cub scouts, miners, potholers, etc.; and 7. A Prison Warder monitoring a group of parole prisoners.

In case 3 and 4 above, two or more guardian units 9 could be provided, allowing one or more teacher(s) to roam among the children and round up errant children while the other / another remained at the rendezvous point to cope with the usual cuts and grazes and other minor 'emergencies'.

In cases 4 and 5 above, the guardian unit 9 could be connectable (not shown) to a fixed computer to keep a permanent record of when who was where so that the build up to an event, e.g. a child running away from school or a baby being abducted from a Matemity Ward, could be ascertained. This might be useful in conjunction with CCTV surveillance.

When such an event occurred, guardian unit 9 would be disconnected (not shown), e.g. by simply pulling a plug out, and used in the manner described to pursue the errant child or abductor. Altematively, a second guardian unit could be provided or the connection could be via a radio link.

Altematively, guardian units 9 could have extra memory to record the spatial distribution of the children for a period of time, e.g. an hour. (This feature would be similar to the 'black boxes' in aircraft, but have the facility to retain the memory indefinitely and download it to another computer, if required.) In the event of a serious incident, the memory could be accessed to determine the build up to the incident. For outdoor use, a special connection (not shown) could be provided from guardian unit 9 to a lap top or palm top (not shown) computer and the larger screen used to display the screen 16 image. This would allow the IDs of a large group all to be detemmined. Alternatively, the memory from unit 9 could be downloaded and the build up to the incident studied in more detail. This could provide valuable forensic evidence in the event that a crime had been committed.

The principle of the apparatus of the invention may also be used in reverse, i.e. to detect a prohibited person entering an area. One example could be a pedophile on the Sex Offender's Register, approaching a school. In this case, the pedophile would have been fitted with an electronic tag, which would be detected by guardian unit 9 when he / she came within range 14 and a warning sounded and / or texted to guardian unit 9. The location of the pedophile would be shown (Fig. 6). As soon as he / she crossed the defined area 13, guardian unit 9 in the school would alarm and identify the pedophile from the signal 11 B. This could be a national scheme and monitor all those on the national register, even when they were on holiday in another part of the country. This aspect of the invention could also be applied to electronically tagged parole prisoners.

Claims

Claims: 1 1 A portable apparatus by which a guardian can monitor

continuously the location of a person(s) or an object(s) within a defined area, comprising: i) a guardian unit having an aerial, able to transmit a signal to a receiving unit, and able to receive signals transmitted from the receiving unit; ii) a lightweight, unobtrusive receiving unit, (each) having a unique electronic identification and adapted to be worn by the person(s) or attached to the object(s), and able both to receive a signal from the guardian unit and to transmit an acknowledgement signal back to the guardian unit; iii) means, within the guardian unit, to define the pemmitted area and its boundary within which the person or object may move; iv) discrimination means, within the guardian unit, to analyse the acknowledgement signal and to detect when the / a person(s) or object(s) has crossed the boundary and left the pemmitted area and identify that person or object from its electronic identification; v) warning means in / on the guardian unit to warn the guardian that no acknowledgement signal has been received from the receiving unit and / or that the person(s) or object(s) has crossed the boundary and left the permitted area; vi) a directional means on the aerial, within the guardian unit, able to indicate the direction of the person(s) or object(s) outside the permitted area from the guardian unit; and vii) a display means on the guardian unit having a first mode of operation in which the spatial distribution of the current location(s) of (all) the person(s) or object(s) is / are displayed using polar co-ordinates and a second mode of operation in which the direction from the guardian unit to that person or object that has crossed the boundary and left the permitted area is displayed; characterized in that the guardian unit communicates at regularly timed intervals with the receiving unit and receives acknowledgements from the receiving unit to confirm both that the apparatus is working normally and that the person or object is within the permitted area but, when the apparatus detects a fault and / or the / a person or object leaves the permitted area, the guardian unit recognises the fact, warns the guardian of the occurrence and allows the guardian to determine the direction in which to proceed to find the errant person or object.
2 A portable apparatus as claimed in claim 1, wherein the guardian unit is enclosed in a case, with the aerial at one end and adapted to be held in a hand and / or carried in a suitable pocket / holder.
3 A portable apparatus as claimed in claim 2, wherein the display means on the guardian unit indicates the relative direction(s) and distance(s) of the person(s) or object(s) from the guardian unit.
4 A portable apparatus as claimed in any preceding claim, wherein the receiving unit is incorporated into a decorative or functional item which a person may wear so that it does not affect their movements or actions or can be attached unobtrusively to an object...
A portable apparatus as claimed in claim 4, wherein the decorative or functional item is a badge, or broach worn by the person(s) or attached to the object(s).
6 A portable apparatus as claimed in claim 4, wherein the decorative or functional item is a watch or wristband.
7 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is provided with means to determine the permitted area.
8 A portable apparatus as claimed in claim 7, wherein the guardian unit is provided with means to define a zone within the pemmitted area.
9 A portable apparatus as claimed in claims 7 and 8, wherein the pemmitted area and zone within the permitted area are defined as radial distances from the guardian unit.
A portable apparatus as claimed in claim 9, wherein particular radial distances are set for the / each individual person or object for the permitted area and zone within the pemmitted area.
11 A portable apparatus as claimed in any preceding claim, wherein the warning means on the guardian unit is operated if an acknowledgement signal is not returned from the receiving unit to the guardian unit following transmission of a signal from the guardian unit to the receiving unit.
12 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is provided with means to assess the radial distance of the receiving unit from the guardian unit and also with discrimination means to identify when the receiving unit is at a distance greater than that defined by either the zone within the permitted area or the permitted area itself and to operate the warning means when the discrimination means determines that one / both of the permitted distances has / have been exceeded.
13 A portable apparatus as claimed in claims 11 and 12, wherein the warning means is audible in nature.
14 A portable apparatus as claimed in claims 11 and 12, wherein the warning means is visible in nature.
A portable apparatus as claimed in claims 11 and 12, wherein the warning means is vibratory in nature.
16 A portable apparatus as claimed in claim 14, wherein the visible warning is flashing on the display means indicating which of a plurality of receiving units is outside the zone within the permitted area or outside the permitted area itself.
17 A portable apparatus as claimed in claims 11 - 16, wherein, when the discrimination means in the guardian unit detects a receiving unit outside the zone within the permitted area or outside the pemmitted area itself, it operates the guardian warning unit and also causes a special signal to be sent to the receiving unit, which causes the receiving unit to emit either a warning audible or visible to the wearer or a vibration detectable by the wearer.
18 A portable apparatus as claimed in claim 17, wherein a first audible, visible or vibratory warning is produced by the guardian unit and by the receiving unit when the person wearing, or the object carrying the receiving unit, leaves the zone within the permitted area.
19 A portable apparatus as claimed in claim 17, wherein a second audible, visible or vibratory warning is produced by the guardian unit and by the receiving unit when the person wearing, or the object carrying, the receiving unit leaves the permitted area.
20 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is provided with a second mode of operation wherein the aerial is provided with directional array capabilities to identify the direction of the errant person / object from the guardian unit.
21 A portable apparatus as claimed in claim 20, wherein, when the guardian unit is in the second mode of operation, the display means indicates visually the direction of the errant person / object from the guardian unit.
22 A portable apparatus as claimed in claims 20 or 21, wherein, when the guardian unit is in the second mode of operation, the direction to the errant person / object is indicated audibly, visibly and / or via a vibration.
23 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is connectable to another computing means having a larger display means and / or greater computing power so that the spatial distribution of the persons or objects being monitored can be determined in greater detail, including the exact location of each person or object being monitored.
24 A portable apparatus as claimed in claim 23, wherein the guardian unit has means to record the spatial distribution of the person(s) or object(s) over a given time period so that the movement of a particular person or object over that time period can be determined.
25 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is provided with means to call the / some of / all person(s) / object(s) being monitored via audible, visible or vibratory means through their receiving units.
26 A portable apparatus as claimed in claim 25, wherein the display means on the guardian unit is a display screen and the means to call the / some of / all person(s) / object(s) being monitored is by touching a part / all of the screen.
27 A portable apparatus as claimed in any preceding claim, wherein a first guardian unit is provided with means to communicate with a second guardian unit so that, when a person / object leaves the permitted area the guardian in the most appropriate position can use their guardian unit, in its second mode of operation, to find and retrieve the errant person / object while the other guardian unit continues to monitor the other person(s) / object(s) within the permitted area.
28 A portable apparatus as claimed in any preceding claim, wherein the guardian unit continuously monitors the location of a plurality of persons or objects, each person or object having a receiving unit with its own unique identification so that the guardian unit can determine which of the plurality of persons or objects is inside the zone within the permitted area, leaving the zone within the permitted area or leaving the permitted area itself.
29 A portable apparatus as claimed in claim 28, wherein the guardian unit is preprogrammed with the unique identifications of the / each one of the plurality of receiving units.
30 A portable apparatus as claimed in claims 28 or 29, wherein the guardian unit has means to program the unique identifications of the / each one of the plurality of receiving units into its memory.
31 A portable apparatus as claimed in claims 29 or 30, wherein the guardian unit has means to recognise, which one of the plurality of receiving units identified in its memory is to be monitored at any particular time.
32 A portable apparatus as claimed in claims 28 - 31, wherein the guardian unit has means to add an additional receiving unit to the plurality of receiving units already identified in its memory and to be monitored at that particular time.
33 A portable apparatus as claimed in claims 28 - 32, wherein the guardian unit has means to delete a receiving unit from the plurality of receiving units already identified in its memory and to be monitored at that particular time.
34 A portable apparatus as claimed in any preceding claim, wherein the guardian unit has means to communicate with a selected receiving unit or some of or all of the receiving units to cause the receiving unit(s) to emit an audible, visual or vibratory warning to the wearer / person with the object.
A portable apparatus as claimed in claim 34, wherein the receiving unit has a means to transmit an emergency signal back to the guardian unit to cause the guardian unit to emit a particular audible, visual or vibratory warning to alert the guardian that the person / object / one of the plurality of persons / objects being monitored was in danger and required immediate assistance.
36 A portable apparatus as claimed in any preceding claim, wherein antiabduction features are incorporated into the receiving units.
37 A portable apparatus as claimed in any preceding claim, wherein the guardian and receiving units have individual power sources, which are replaceable, or rechargeable
38 A portable apparatus as claimed in any preceding claim, wherein the guardian has means to recognise the presence of a prohibited person wearing a receiving unit approaching, or within, the permitted area and alerting the guardian audibly and / or visually and / or by vibratory means and / or by a text message on the display screen.
39 A portable apparatus as claimed in any preceding claim, wherein the guardian unit is incorporated into a mobile telephone or other appropriate electronic device.

A portable apparatus as claimed in and by the above description with reference to the accompanying drawings.