CA1301844C - Personal security communication system - Google Patents
Personal security communication systemInfo
- Publication number
- CA1301844C CA1301844C CA000596088A CA596088A CA1301844C CA 1301844 C CA1301844 C CA 1301844C CA 000596088 A CA000596088 A CA 000596088A CA 596088 A CA596088 A CA 596088A CA 1301844 C CA1301844 C CA 1301844C
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- Prior art keywords
- alarm
- signal
- motion
- portable unit
- housing
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Abstract
PERSONAL SECURITY COMMUNICATION SYSTEM
Abstract of the Disclosure A personal security communication system is disclosed. The system may be configured as a buddy system comprising first and second portable portable units (100 and 200) acting as a pair (98). Each portable unit (100 and 200) produces status information and transmits data messages containing encoded status information to the other portable unit (200 and 100). The encoded status information includes a transmitting unit identification number and alarm condition information produced by manual alarm switches (104 and 204) and sensors (102 and202). The sensors (102 and 202) may include a motion sensor (45) or a motion andposition sensing switch (10) that produce motion and lack-of-motion signals thatare encoded in the status information. If one unit of the pair (98) produces status information containing emergency alarm information or receives a data message from the other unit of the pair (98) containing emergency alarm information or fails to receive a data message from the other unit of the pair (98) within a predetermined time limit, an alarm is produced.
Abstract of the Disclosure A personal security communication system is disclosed. The system may be configured as a buddy system comprising first and second portable portable units (100 and 200) acting as a pair (98). Each portable unit (100 and 200) produces status information and transmits data messages containing encoded status information to the other portable unit (200 and 100). The encoded status information includes a transmitting unit identification number and alarm condition information produced by manual alarm switches (104 and 204) and sensors (102 and202). The sensors (102 and 202) may include a motion sensor (45) or a motion andposition sensing switch (10) that produce motion and lack-of-motion signals thatare encoded in the status information. If one unit of the pair (98) produces status information containing emergency alarm information or receives a data message from the other unit of the pair (98) containing emergency alarm information or fails to receive a data message from the other unit of the pair (98) within a predetermined time limit, an alarm is produced.
Description
~3~
62~39-113S
Field of the Invention This invention relates to personal security communication systems and more particularly to motion sensing alarms and motion and position sensors.
Description of the Prior Art A number of occupations where workers are isolated and working in dangerous environments require that the workers be continuously monitored. For example, a security guard making his rounds on the premises of a buildlng may be required to inform a central office of his whereabouts.
Within the forest industry, the forest workers face the greater dangers. A buddy system of monitoring worker'~ status is used extensively. Prior art buddy systems usually require a worker to occasionally ~top working and physlcally monitor the work of hls buddy. The ma~or shortcoming of these prior art systems is that an emergency ~ituation is only detected when the buddy stops work to monitor the situation, and accordingly, productlvity i6 affected by requiring the workers to pause perlodlcally.
In another prior art buddy system, the workers are in a group wlth one member whose sole responslbility is to detect if any member of the group ls in need of assistance. This is usually accomplished by having this member move from one worker to the next and verifying that all ls well within the group. In these sltuations, the group productlvlty ls llmlted because one member of the group i5 not able to work contlnuously.
Another prior art buddy system utilizes two-way voice radios permlttlng a worker to communicate with his buddy. When one worker ls in need of assistance, 1301~344 that worker can use his radio to call his buddy for help. One problem associated with this prior art system is that if the worker in need of assistance becomes disabled le.g., unconscious) he may not be able to call his buddy. Another problem associated with the prior art buddy ~ystems is their lack of a fail-safe feature. That is, when either one of the radios becomes nonfunctional, such as when a radio is broken or out of range, a worker s call for assistance will not be received by his buddy.
Thus, a communication failure between the radios will prevent an emergency call from being heeded by the buddy.
A~ can be readily appreciated from the foregoing discussion, there is a need for a buddy communication system that automatically communicates worker status information between radio units. Further, the buddy commur.icatlon system should have a fail-safe feature, such that a failure to receive status information for a predetermined period of time causes a communicatlon failure alarm. The pre~ent invention is a personal securlty sys~em designed to achieve these results.
Summarv of the Invention In accordance with one aspect, the present invention provides a personal security communication system configured to operate as a buddy system, said system comprising: (a) a first portable unit for producing a first status signal and receiving a second status signal, said first portable unit transmitting said flrst status signal as a radio frequency carrier signal modulated with data messages, said first portable unlt producing an alarm when said first status signal include~ emergency alarm information, and said first portable unit also producing an alarm when said second status signal includes emergency alarm informatlon, said first portable unit further produciny an alarm when sald second status signal is not received for a predetermined period of time; and , (b) a second portable unit for producing said second status signal and receiving said first status signal, said second portable unit transmitting said second status signal as a radio frequency carrier signal modulated with data messages, 1301~344 said second portable unit producing an alarm when said first status signal includes emergenc~ alarm condition information and said second portable unit also producing an alarm when said second status signal includes emergency alarm condition information, said second portable unit further producing an alarm when said first status signal is not received for a predetermined period of time.
In accordance with another aspect of the present invention, there is provided a portable unit for use in a personal security communication system comprising: a housing adapted to be worn by an individual; a signaling unit integral with said housing including a manually actuatable switch for producing an alarm signal and a motion sensor for generating a motion signal whenever said housing is in motion; a processing means connected to said signaling unit for receiving said alarm signal and said motion signal and for producing status information signals of said received signals including a processor alarm signal which is a~serted when said manual alarm signal is asserted or when said motion signal indicates said housing has been motionless for a selected amount of time; a transceiver connected to said processing means transmitting and receivlng status information signals from and to said processor means, wherein said status information signals are transmitted and received in the form of data messages; an alarm connected to said processing means for recelving said processor alarm signal and actuatable in response to receiving said processor alarm signal; and, a power supply coupled to supply power to said processing means, said transmitting means, and said alarm.
In accordance with a further aspect of the present lnvention, there is provided a personal safety unit comprising: a housing adapted to be worn by an individual; a motion detector lntegrally attached to said housing including: a motion sensor including two mechanical elements arranged such that one said mechanical element moves in and out of contact with the other said mechanical element when said housing is in motion and such that said sensor produces a motion signal indicative of contact status ~3018~4 62839-113~
of said mechanical elements; and a detect circuit coupled to said motion ~ensor for receiving said motion signal, moni~oring same, and producing an alarm signal when said houæing is motionless for a selected amount of time; an alarm device integral with said housing and connected to receive said alarm signal and responding to said alarm signal by producing an alarm.
According to yet another aspect, the invention provides a motion sensor adapted to indicate motion and lack of motion, comprising: an enclosure with an open end; a base for covering said open end; pressure sensitive electrical sensing means on said base, facing said enclosure and motion sensitive weight means in said enclosure adapted to move freely in said enclosure such that when said weight means move over said sensing means, an electrical signal lndicative of the motion of said weight means over said sensing means can be detected.
Brief Description of the Drawin~s Particular embodiments of the lnvention will be understood in conjunction with the accompanying drawings in which:
FIGURE 1 is a sectional view of a motion and position sensing switch;
FIGURE 2 i~ a sectional view of the sensing switch of FIGURE 1 shown pivoted from a horizontal to a vertical position;
FIGURE 3 is a top view of a cond~ctive circuit used with the sensing switch of FIGURE l;
FIGURE 4 is a block diagram of a motion sensor circuit using the motion and positlon sensing switch;
FIGURE 5 is a sectional view of a second type of motion sensor;
FIGURE 6 is a block diagram of a personal security communication system using a position/motion sensor;
FIGURE 7 is a flow chart for a nonpolling base station;
FIGURE 8 is a flow chart for the portable units used in a nonpolling network;
FIGURE 9 is a flow chart for a polling base station;
FIGURE 10 is a flow chart for portable units used in a - polling network;
3a 62~39-1138 FIGURE 11 is a block diagram of the personal security communication system in a buddy system configuration;
FIGURE 12 is a perspective view of a portable unit suitable for use in the system depicted in FIGURE 11; and, 3b ; 1 ' ~
13018~4 FIGURES 13 and 14 are flow charts for the buddy system illustrated in FIGURE 11.
Description of the Preferred Embodiments Referring now to FIGURE 1, we have shown, generally at reference 5 numeral 10, a sectional view of a motion and position sensing switch. When placed in a horizontal position, the switch is in the off state.
The motion and position sensing switch is comprised of an electrically conductive enclosure 11 having a truncated cone-shaped cavity 12. It will be understood by those knowledgeable in this art that cavity 12 may have other 10 shapes as well. Enclosure 11 and cavity 12 are capped by means of a plate 13 having a conductive circuit 14, electrically isolated from enclosure 11. Plate 13 is secured onto enclosure 11 by means of fasteners 15 which can consist of self-tapping screws and the like. A conductive ball 16 is used as a contact making element between conductive enclosure 11 and conductive circuit 14.
A pair of conductors 17a and 17b can be connected to a suitable detecting circuit (not shown) adapted to monitor the change of state of switch 10. The interior edge 18 of cavity 12 makes an angle of 30 from a vertical axis. When switch 10 pivots about the horizontal axis to an angle greater than 60 from thevertical axis, conductive ball 16 rolls to the outer edge 19 of cavity 12, thereby 20 allowing contact to be made between enclosure 11 and conductive circuit 14. (See FIGURE 2). In this position, switch 10 now turns to an active state since current is allowed to flow from enclosure 11 to conductive circuit 14 and to a detectingcircuit via conductor 17a and 17b.
Referring now to FIGURE 3, we have shown a top view of the conductive 25 circuit shown at reference numeral 14 of FIGURES 1 and 2. Conductive circuit 14 is comprised of a gold-plated circuit etched on a nonconductive surface 21. In the present embodiment, conductive circuit 14 forms two separate electrical conductive regions. These regions are comprised of a first set of conductive lines or fingers 22 extending outwardly from a central conductive region 23. Each 30 finger is positioned radially in spaced relationship. A second set of lines or fingers 24 extend inwardly from a peripheral conductive ring 25 located outwardly from the first set of lines 22. The second set of lines 24 are positioned radially in spaced relationship adjacent to the first set of lines 22. A separate conductiveline 26 is used to connect conductive ring 25 to a central conductive region 27 35 Iying adjacent to conductive region 23. The first and second set of lines areelectrically isolated from one another. Conductive regions 23 and 27 are individually connected to a detecting circuit (not shown) by means of conductors 17a and 17b, respectively.
Conductive circuit 14 allows switch 10 to provide, while in the active state, three possible electrical state changes. For example, conductive ball 16 can make electrical contact between enclosure 11 and conductive fingers 22, between enclosure 11 and conductive fingers 24 and between enclosure 11 and conductive 5 fingers 22 and 24. That is, the conductive ball 16 can make contact with fingers 22, 24 or both.
Similarly, conductive circuit 14 could be designed with a single set of conductive fingers separated by nonconductive fingers, thereby allowing a detecting circuit to detect a change of state of the motion sensing switch. It will 10 be understood by those knowledgeable in this art that other circuit designs can be used to arrive at the same results without departing from the scope of the invention.
Referring now to FIGURE 4, a block diagram of a motion sensor circuit is depicted at reference numeral 30. The motion sensing switch is depicted by 15 circuit 31 defined by the dotted line. Switch 32 represents the opening and closing of electrical contact made by the conductive ball between enclosure 11 and fingers 22. Conductor 17a leads from switch 31 to a transistor switching circuit 33. Enclosure 11 is connected to ground by means of conductor 34 which is not shown in FIGURES 1 and 2 for sake of clarity. Switch 35 represents the 20 opening and closing of electrical contact made by conductive ball 16 between enclosure 11 and fingers 24. Conductor 17b connects conductive region 27 to transistor switching circuit 36.
The collectors 37 and 38 from the transistor switching circuits 33 and 36 are connected to a buffer circuit 39. The output of the buffer circuit is then 25 connected to a microprocessor 40.
The microprocessor 40 senses the two switch inputs. Whenever the microprocessor detects a change of state created by switch 32 and 35, i.e., switch 32 open, switch 35 closed, switch 32 closed, switch 35 open or switch 32 and 35 closed, an internal timer (not shown) is reset and activated. However, if30 the timer reaches a preset value before a change of state is detected, then an alarm is initiated. This would occur, for example, if conductive ball 16 remained motionless making contact between enclosure 11 and conductive circuit 14.
In another embodiment, motion sensing switch 10 could be made of a non-conductive enclosure and provided with a conductive region near the outer edge of 35 the cavity, such that when the contact making element moves to the outer edge of the cavity, contact is made between ground and the conductive circuit.
13~844 Referring now to FIGURE 5, we have shown at reference numeral 45 a sectional view of a motion sensor according to another embodiment of the presentinvention. The sensor is comprised of an enclosure 46 having an open end shown generally at reference numeral 47 which is covered by means of a base 48 and 5 secured therein by means of a channel 49 formed by a pair of ridges 50 and 51.Base 48 is provided with a pressure sensitive electrical sensor 52 which can consists of a piezoelectric element. A motion sensitive weight, such as ball bearing 53, is retained within enclosure 46 and can freely move therein. Leads 54 and 55 are connected to a detection circuit adapted to monitor any electrical 10 impulses generated which are indicative of the motion of ball bearing 53 on base 48.
Such a sensor, because of its ruggedness and simplicity, is well suited for applications in the logging industry.
Referring now to FIGURE 6, we have shown a block diagram of one 15 embodiment of a personal security communication system formed in accordance with the present invention. While the system illustrated in FIGURE 6 and discussed below utilizes a position/motion sensor 61, it is to be understood that the system may utilize other types of sensing devices, such as a gas detector or a heart monitor, for example. Furthermore, the system may utilize more than one 20 sensing device or no sensing device.
In this system, the microcomputer 60 is the heart of the system. ln the particular embodiment illustrated in FIGURE 6, the microcomputer 60 is responsible for monitoring the status of the user by means of the position/motion sensor 61 or manual input 62. Manual input 62 is basically comprised of a switch25 which is activatable by the user when an alarm condition exists. If, however, the user has become disabled, the position and motion sensor 61 can detect the existence of an alarm condition. If an alarm condition exists, microcomputer 60 will format a digital data message to be transmitted through a radio transmitter 63 via antenna 64 to other units in the system or to a central station.
30 When this condition exists, microcomputer 60 would activate signaling means such as beeper 65 and/or light emitting diode 66 forming part of each unit. A digitalradio receiver 67 and receiving antenna 68 are provided with each unit. The microcomputer 60 listens to the signal provided by radio receiver 67 for messages coming from other units or from a base station. Computer 60 controls the 35 beeper 65 and light emitting diode 66 to display the status of the system.
The microcomputer 60 may consist of, but is not limited to, an Intel 8051 microcontroller and external, single component EPROM memory chip. The radio transmitter 63 and receiver 67 are capable of transmitting and receiving a digital data message. The on/off keying and modulation of the transmitter 63 can be controlled by microcomputer 60. The receiver 67 will normally be on, and turned off during transmission. The power supply 69 is used to provide power to radio 5 transmitter 63, receiver 67, microcomputer 60, beeper 65 and light emitting diode 66. The power supply can consist of a Nicad rechargeable battery pack.
The system can be enclosed in a small housing and belt mounted.
The system can be configured with two units operating in a buddy system, where each unit monitors the other's status or in a group system, where the status 10 of all the working units is monitored frorn a base station.
As indicated above, different modes of operation are possible using the present system. For example, in a nonpolling network, each user would carry a unit having only the transmitter rather than both transmitter and receiver. The transmitter would be activated upon occurrence of an alarm condition. A signal 15 would then be transmitted to a base station which would monitor all transmissions from each unit in the field. The information flow chart for both the base station and a unit is shown in FIGURES 7 and 8, respectively.
The communication system may also operate in a polling network, wherein each unit worn by a worker in a group of workers is provided with a transmitter 20 and a receiver. A base station will continuously poll the status of each individual. For example, the base station will poll a first portable unit and await a response prior to polling a second portable unit. If no response is received after a specified time, the alarm will be activated. The information flow chart for the base station is shown in FIGURE 9. The information flow chart for the portable 25 units is depicted in FIGURE 10.
As indicated above, the personal security communication system may also be configured as a buddy system. In a buddy system configuration, two portable units work as a pair. The portable units are bilateral, such that each unit includes areceiver and transmitter, preferably, in the form of a transceiver. As will become 30 better understood from the following discussion, each portable unit transmitsencoded status information in the form of a data message, such as a digital datamessage, for example, to the other unit in the pair. More specifically, the portable units transmit encoded status information as a radio frequency carrier signal modulated with data messages. The data message is transmitted 35 continuously at regular intervals. As will also become better understood from the following discussion, the encoded status information in each message includes a transmitting unit identification number and alarm condition information. The 13018~4 other unit of the pair receives the data message and alerts a worker wearing thereceiving unit if the alarm condition information indicates an emergency alarm condition exists at the transmitting unit. The receiving unit also alerts the worker of an out-of-range or malfunctioning transmitting or receiving unit when a data 5 message is not received for a predetermined period of time (i.e., a communication failure alarm).
FIGURE 11 is a block diagram of a preferred embodiment of the personal security communication system configured as a buddy system. A first portable unit 100 and a second portable unit 200 operate as a unit pair 98. The first 10 portable unit 100 comprises: one or more sensors 102, a manual alarm switch 104;
a power supply 106; a microcomputer 108; a digital transceiver 110; an alarm 112;
an ON-OFF-REST switch 116; and, an antenna 114. The power supply 106 provides power to the microcomputer 108, transceiver 110, and the alarm 112 via line 124. The microcomputer 108 receives sensor input signals from the 15 sensors 102 via line 120 and a manual alarm input signal from the manual alarm switch 10~ via line 122. The microcomputer 108 produces encoded status information on line 126. The transceiver 110 receives the encoded status information and transmits a digital data message to the second portable unit 200via the antenna 114.
The ON-OFF-REST switch 116 (hereinafter referred to as switch 116) is connected to the microprocessor 108 via line 132. The switch 116 is preferably athree position switch. When the switch is in the OFF position, the unit 100 is off and cannot receive or transmit data. When the switch 116 is in the ON position, the unit 100 operates in a normal manner, which is discussed below. As will 25 become better understood from the following discussion, when the switch 116 is in the REST position at least one of the sensors 102 is disabled. When the switch 116 is in the REST position the unit 100 continues to operate as if the switch 116 was in the ON position, with the exception of the sensors 102 that are disabled.
The second portable unit 200 is identical to the first portable unit 100 30 discussed above. More specifically, the second portable unit 200 comprises: one or more sensors 202; a manual alarm switch 204; a power supply 206; a microcomputer 208; a digital transceiver 210; an alarm 212; an ON-OFF-REST
switch 216; and, an antenna 214. The power supply 206 supplies power to the microcomputer 208, the transceiver 210 and the alarm 212 via line 224. The 35 microcomputer 208 receives sensor input signals from the sensors 202 via line 220 and a manual alarm input signal from the manual alarm switch via line 222. The microcomputer 208 produces encoded status information on line 226. The 130~844 g transceiver 210 receives the encoded status information and transmits a digital data message to the first portable- unit 100 via antenna 214.
The ON-OFF-REST switch 216 (hereinafter referred to as switch 216) is connected to the microprocessor 208 via line 232. The switch 216 is preferably a5 three position switch that controls the unit 200 in a manner similar to that discussed above for the switch 116 and the unit 1û0.
Microcomputers 108 and 208 are preferably identical to the microcomputer 60 discussed above and illustrated in FIGURE 6. Likewise, the power supplies 106 and 206 are, preferably, identical to the power supply 69 10 (FIGURE 6) and the manual alarm switches 104 and 204 are, preferably, identical to the manual input 62 (also FIGURE 6). The digital transceivers 110 and 210 are, preferably, conventional digital transceivers and operate substantially the same as the digital radio transmitter 63 and receiver 67 discussed above and illustrated in FIGURE 6. The alarms 112 and 212, preferably, include visual and audible alarms 15 substantially the same as the beeper 65 and LED 66 also noted above and illustrated in FIGURE 6. Accordingly, these elements of the present invention are not discussed below in further detail.
The sensors 102 and 202 may include a motion sensor identical to the motion sensor 45 discussed above and illustrated in FIGURE 5. The sensors 102 and 202 20 may also include a motion and position sensing switch identical to the switch 10 discussed above and illustrated in FIGUl~ES 1-3. In any event, the motion sensorand/or the motion and position sensing switch may, in accordance with an actual working embodiment of the present invention, be disabled by activating the switches 116 and 216. Preferably, other functions of the units 100 and 200 are 25 unaffected by the switches 116 and 216. As noted above, the sensors 102 and 202 may also include other types of sensing devices, such as a gas detector or a heart monitor, for example. Furthermore, the sensors 102 and 202 may include multiple sensing devices. The units 100 and 200 may also function without sensors 102 and202, such that microcomputers 108 and 208 receive only the input signals from the 30 manual alarm switches 104 and 204, respectively.
The digital data message transmitted by the first portable unit 100 is received by the transceiver 210 in the second portable unit 200 via the antenna 214. The microcomputer 208 receives the encoded status information via line 228. The microcomputer 208 decodes the status information and, if 35 appropriate, sends an alarm signal to the alarm 212 via line 230. Similarly, the first portable unit 100 receives a digital data message from the second portableunit 200 via the antenna 114. The microcomputer 108 receives the encoded status ~:~018~
information on line 128 and decodes the status information. If appropriate, the microcornputer 108 sends an alarm signal to the alarm 112 via line 130. As will become better understood from the following discussion, the microcomputers 108 and 208, preferably, produce different alarm signals for different alarm conditions 5 indicated by the status information. Accordingly, the alarms 112 and 212, preferably, produce different alarms related to the different alarm signals.
If an emergency alarm condition exists, which is determined by the input signals on lines 120 and 122 for the unit 100, and on lines 220 and 222 for the unit 200, the microcomputer 108 and 208 also send alarm signals to their 10 respective alarms 112 and 212. For example, if a user activates the manual alarm switch 104 in the first portable unit 100~ the microcomputer 108 encodes this manual alarm signal into a digital data message that is transmitted to the second portable unit 200 and an alarm is produced at the second portable unit 200. The microcomputer 108 in the first portable unit 100 also sends an alarm signal to the 15 alarm 112 in the first portable unit 100 via line 130. The alarm in the firstportable unit 100 informs the worker that he has initiated an emergency alarm.
The microcomputer 108 also monitors the power supply 106 and alerts the worker wearing the first portable unit 100 if a low power supply volta~e exists. More specifically, the microcomputer 108 produces an alarm signal on line 130 if a low 20 power supply voltage is detected on line 124. Likewise, the microcomputer 208 in the second portable unit 200 monitors the power supply voltage on line 224 and produces an alarm signal on line 230 if a low power supply voltage is detected.
Preferably, the units 100 and 200 permit false alarms to be cleared before they are transmitted to the other unit. A delay (e.g., 5 seconds) permits false 25 alarm input signals to be cleared by a worker wearing the transmitting unit. For example, if a worker wearing unit 100 inadvertently activates the manual alarm switch 104, an alarrn signal will be produced on line 122. The unit 100 will delay (for an appropriate period of time) encoding the signal and transmitting an emergency alarm condition in the data message to allow the worker to clear the 30 false alarm. The false alarm may be cleared by turning the unit 100 off (via the switch 116) and then turning the unit 100 back on. The other unit 200 works similarly.
FIGURE 12 is a perspective view of one preferred embodiment of the first portable unit 100 discussed above. The second portable unit 200 is not depicted in 35 FIGURE 12 for purposes of clarity. Accordingly, it is to be understood that the various features illustrated in FIGURE 12 and discussed below for the first portable unit 100 are identical to the respective features of the second portable 130~844 unit 200. The first portable unit 100 has a housing 150 that is, preferably, made of a rugged material, such as a mgh impact,-shock resistant plastic, for-example.
However, other suitable materials may also be used. The antenna 114, the manual alarm switch 104, and the ON-OFF-REST switch 116, preferably, extend from a 5 top surface 154 of the unit 100. A guard 152, preferably, extends above the top surface 154 and at least partially encloses the antenna 114 and the switches 104and 116. A belt loop 156 is formed by a bracket 158 attached to, or formed by, the housing 150. A worker's belt 160 passes through the belt loop 156, thus, making it easy for the worker to wear the first portable unit 100 while performing 10 a job task. The bracket 158 may be made of a rigid material similar to the housing 150 or may be made of another type of material, such as flexible strapping material, for example.
FIGURES 13 and 14 are information flow charts for the buddy system configuration of the personal security communication system illustrated in 15 FIGURE 11 and discussed above. More specifically, the flow charts represent the functional steps of a program that controls the microcomputers 108 and 208. The information flow charts illustrated in FIGURES 13 and 14 are identical for both units 100 and 200 in the unit pair 98. Accordingly, for purpcses of clarity, theflow charts illustrated in FIGURES 13 and 14 are described below for the first 20 portable unit 100.
The system becomes operational when one or both of the units 100 or 200 in the buddy system are turned on. The start block at the top of FIGURE 13 represents the first portable unit 100 being turned on. Once the unit 100 has been turned on, the program instructs the microcomputer 108 to initialize various 25 timers and the status information associated with the unit 100. More specifically, a motion timer, a transmit timer and a message timer are initialized. As will become better understood from the following discussion, the transmit timer regulates the time interval between transmissions of digital data messages to the other unit 200. The motion timer monitors the time interval during which no 30 movement is detected by the first portable unit 100. The message timer monitors the time interval between consecutive data messages transmitted by the other unit 200. Also during this step, the status information is initialized, so that, for example, any prior emergency alarm conditions are cleared. After the initialization step, each of the timers is incremented and the program proceeds to 35 the next step.
Once the timers have been incremented, the program instructs the microcomputer 108 to perform a power supply low voltage test. As noted above, 130~il44 if the microcomputer 108 determines that the power supply voltage is low (i.e., below a predetermined threshold level) an alarm signal is applied to the alarm 112 in the first portable unit 100. In accordance with the preferred ernbodiment of the invention, this power supply low voltage alarm is not transmitted to the 5 second portable unit 200. During this step the program also instructs the microcomputer 108 to determine whether a manual alarm has been initiated. If the microcomputer 108 determines that a manual alarm has been initiated (i.e., detects a manual alarm signal on line 122~, the status information is updated toreflect the emergency alarm condition.
Next, and in accordance with a preferred embodiment of the invention, the program instructs the microcomputer to determine whether there has been movement by the user or whether a lack-of-motion alarm signal should be produced. More specifically, the microcomputer 108 receives motion sensor signals from a motion sensor, such as the motion sensor 45 illustrated in 15 Fl~:URE 5, for example. The motion sensor 45 produces a motion sensor signal each time movement of the worker is detected. When a motion sensor signal is received by the microcomputer 108, the motion timer is cleared and the status information updated accordingly. If the microcomputer 108 does not sense a motion sensor signal, the program then determines whether the time interval 20 measured by the motion timer has exceeded a maximum allowable time limit (i.e., a predetermined time interval, such as one minute, for example). If the time interval measured by the motion timer exceeds the maximum allowable time limit, a lack-of-motion alarm condition exists. As a result, the status information is updated to include emergency alarm information that reflects the lack-of-25 motion alarm condition. Once the status information has been updated, theprogram proceeds to the next step, which is discussed below. If the microcomputer 108 does not sense a motion sensor signal and the time interval measured by the motion timer does not exceed the maximum allowable time limit, the program bypasses the status information update step and proceeds directly to30 the next step.
Next, the program determines whether it is time to transmit the current status information as a data message to the second portable unit 200. More specifically, if the time interval measured by the transmit timer equals or exceeds a predetermined time limit, such as, four and one-half seconds, for example, the35 program clears the transmit timer and transmits the current status information as a data message to the second portable unit 200. Once the data message has been transmitted, the program returns to increment the cleared transmit timer and the ~301844 and message and motion timers (FIGURE 13). If the program determines that it is not time to transmit the status information, that iS7 if the time interval measured by the transmit timer since the last transmitted message is less than the predetermined time limit, the first portable unit 100 does not transmit the status 5 information as a data message and the program proceeds to the next step.
Turning to FIGURE 14J once the program has determined it is not yet time to transmit the data message, the program determines whether the first portable unit 100 has received a digital data message from the second portable unit 200.
As noted above, the data message transmitted by the second portable unit 200 10 includes encoded status information associated with the second portable unit 200. More specifically, the encoded status information from unit 200 includes an identification number for the second portable unit 200 and alarm condition information associated with the second portable unit 200. If a data message has not been received by the first portable unit 100, the program determines whether15 it has been too long since the last data message was received. More specifically, if the time interval monitored by the message timer does not exceed a maximum allowable time limit (such as two and one-half minutes, for example), the program returns to increment the timers (FIGURE 13). If the time interval monitored by the message timer does exceed the maximum allowable time limit, the program 20 instructs the microcomputer 108 to produce an unit out-of-range/unit malfunction alarm signal. The alarm signal is applied to the alarm 112 (FIGURE 11). Once thealarm signal has been produced, the program returns to increment the timers (FIGURE 13).
If a data message has been received by the first portable unit 100, the 25 program determines whether the received message was transmitted from the second portable unit 200 or from some other unit. Thls is done by the first portable unit 100 when it decodes the data message and compares the unit identification number in the received data message with the identification number of the other unit in the pair (i.e., the second portable unit 200). If the 30 identification number i9 not the same as the second portable unit identification number, then the message was transmitted from another unit and the message is ignored by the first portable unit 100. In this situation the program returns toincrement the timers (FIGURE 13). If the program determines the received message is from the second portable unit 200 (i.e., the received data message 35 contains the second portable unit identification number), the message timer in unit 100 is cleared and the program determines whether the data message includedemergency alarm information. If emergency alarm information was included in 130~844 the received data message, the program instructs the microcomputer 108 to produce-an emergency alarm signal.- The-emergen~y alarrn signal- is applied to the-alarm 112 (FIGURE 11). Next, the program returns to increment the timers (FIGURE 13). If the program determines that emergency alarm information was 5 not included in the received data message, the program returns to increment the timers (FIGURE 13). The program steps are repeated in the manner illustrated in FIGURES 13 and 14 and discussed above until the first portable unit 100 is turned off.
As noted above, one physical embodiment of the present invention includes a 10 rest feature that disables at least one of the sensors 102 illustrated in FIGURE 11 and discussed above (such as the motion sensor d~5, for example). More specifically, if the first portable unit 100 is placed in a rest mode (i.e., if the switch 116 is placed in the REST position, FIGURE 11), the first portable unit 100 will continue to update status information and transmit data messages to the 15 second portable unit 200 and receive data messages from the second portable unit 200. However, while in the rest mode, the first portable unit 100 will not transmit emergency alarm information indicating a lack-of-motion alarm condition to the second portable unit 200. Thus, with the first portable unit 100 in the rest mode, the worker wearing the first portable unit 100 may stop working 20 (i.e., rest) and not send false lack-of-motion alarm signals to the second portable unit 200 while continuing to monitor the second portable unit 200.
As can be readily appreciated from the foregoing description, the invention provides a personal security communication system. While a preferred embodiment of the invention has been illustrated and described herein, it is to be 25 understood that, within the scope of the appended claims, various changes can be made. For example, more than two units can be configured to operate together in a buddy systern. Also, the units in a buddy system rnay communicate with a base station, in addition to communicating with each other. Furthermore, processors other than the microcomputers discussed above may be used. Hence, the 30 invention may be practiced otherwise than as specifically described herein.
62~39-113S
Field of the Invention This invention relates to personal security communication systems and more particularly to motion sensing alarms and motion and position sensors.
Description of the Prior Art A number of occupations where workers are isolated and working in dangerous environments require that the workers be continuously monitored. For example, a security guard making his rounds on the premises of a buildlng may be required to inform a central office of his whereabouts.
Within the forest industry, the forest workers face the greater dangers. A buddy system of monitoring worker'~ status is used extensively. Prior art buddy systems usually require a worker to occasionally ~top working and physlcally monitor the work of hls buddy. The ma~or shortcoming of these prior art systems is that an emergency ~ituation is only detected when the buddy stops work to monitor the situation, and accordingly, productlvity i6 affected by requiring the workers to pause perlodlcally.
In another prior art buddy system, the workers are in a group wlth one member whose sole responslbility is to detect if any member of the group ls in need of assistance. This is usually accomplished by having this member move from one worker to the next and verifying that all ls well within the group. In these sltuations, the group productlvlty ls llmlted because one member of the group i5 not able to work contlnuously.
Another prior art buddy system utilizes two-way voice radios permlttlng a worker to communicate with his buddy. When one worker ls in need of assistance, 1301~344 that worker can use his radio to call his buddy for help. One problem associated with this prior art system is that if the worker in need of assistance becomes disabled le.g., unconscious) he may not be able to call his buddy. Another problem associated with the prior art buddy ~ystems is their lack of a fail-safe feature. That is, when either one of the radios becomes nonfunctional, such as when a radio is broken or out of range, a worker s call for assistance will not be received by his buddy.
Thus, a communication failure between the radios will prevent an emergency call from being heeded by the buddy.
A~ can be readily appreciated from the foregoing discussion, there is a need for a buddy communication system that automatically communicates worker status information between radio units. Further, the buddy commur.icatlon system should have a fail-safe feature, such that a failure to receive status information for a predetermined period of time causes a communicatlon failure alarm. The pre~ent invention is a personal securlty sys~em designed to achieve these results.
Summarv of the Invention In accordance with one aspect, the present invention provides a personal security communication system configured to operate as a buddy system, said system comprising: (a) a first portable unit for producing a first status signal and receiving a second status signal, said first portable unit transmitting said flrst status signal as a radio frequency carrier signal modulated with data messages, said first portable unlt producing an alarm when said first status signal include~ emergency alarm information, and said first portable unit also producing an alarm when said second status signal includes emergency alarm informatlon, said first portable unit further produciny an alarm when sald second status signal is not received for a predetermined period of time; and , (b) a second portable unit for producing said second status signal and receiving said first status signal, said second portable unit transmitting said second status signal as a radio frequency carrier signal modulated with data messages, 1301~344 said second portable unit producing an alarm when said first status signal includes emergenc~ alarm condition information and said second portable unit also producing an alarm when said second status signal includes emergency alarm condition information, said second portable unit further producing an alarm when said first status signal is not received for a predetermined period of time.
In accordance with another aspect of the present invention, there is provided a portable unit for use in a personal security communication system comprising: a housing adapted to be worn by an individual; a signaling unit integral with said housing including a manually actuatable switch for producing an alarm signal and a motion sensor for generating a motion signal whenever said housing is in motion; a processing means connected to said signaling unit for receiving said alarm signal and said motion signal and for producing status information signals of said received signals including a processor alarm signal which is a~serted when said manual alarm signal is asserted or when said motion signal indicates said housing has been motionless for a selected amount of time; a transceiver connected to said processing means transmitting and receivlng status information signals from and to said processor means, wherein said status information signals are transmitted and received in the form of data messages; an alarm connected to said processing means for recelving said processor alarm signal and actuatable in response to receiving said processor alarm signal; and, a power supply coupled to supply power to said processing means, said transmitting means, and said alarm.
In accordance with a further aspect of the present lnvention, there is provided a personal safety unit comprising: a housing adapted to be worn by an individual; a motion detector lntegrally attached to said housing including: a motion sensor including two mechanical elements arranged such that one said mechanical element moves in and out of contact with the other said mechanical element when said housing is in motion and such that said sensor produces a motion signal indicative of contact status ~3018~4 62839-113~
of said mechanical elements; and a detect circuit coupled to said motion ~ensor for receiving said motion signal, moni~oring same, and producing an alarm signal when said houæing is motionless for a selected amount of time; an alarm device integral with said housing and connected to receive said alarm signal and responding to said alarm signal by producing an alarm.
According to yet another aspect, the invention provides a motion sensor adapted to indicate motion and lack of motion, comprising: an enclosure with an open end; a base for covering said open end; pressure sensitive electrical sensing means on said base, facing said enclosure and motion sensitive weight means in said enclosure adapted to move freely in said enclosure such that when said weight means move over said sensing means, an electrical signal lndicative of the motion of said weight means over said sensing means can be detected.
Brief Description of the Drawin~s Particular embodiments of the lnvention will be understood in conjunction with the accompanying drawings in which:
FIGURE 1 is a sectional view of a motion and position sensing switch;
FIGURE 2 i~ a sectional view of the sensing switch of FIGURE 1 shown pivoted from a horizontal to a vertical position;
FIGURE 3 is a top view of a cond~ctive circuit used with the sensing switch of FIGURE l;
FIGURE 4 is a block diagram of a motion sensor circuit using the motion and positlon sensing switch;
FIGURE 5 is a sectional view of a second type of motion sensor;
FIGURE 6 is a block diagram of a personal security communication system using a position/motion sensor;
FIGURE 7 is a flow chart for a nonpolling base station;
FIGURE 8 is a flow chart for the portable units used in a nonpolling network;
FIGURE 9 is a flow chart for a polling base station;
FIGURE 10 is a flow chart for portable units used in a - polling network;
3a 62~39-1138 FIGURE 11 is a block diagram of the personal security communication system in a buddy system configuration;
FIGURE 12 is a perspective view of a portable unit suitable for use in the system depicted in FIGURE 11; and, 3b ; 1 ' ~
13018~4 FIGURES 13 and 14 are flow charts for the buddy system illustrated in FIGURE 11.
Description of the Preferred Embodiments Referring now to FIGURE 1, we have shown, generally at reference 5 numeral 10, a sectional view of a motion and position sensing switch. When placed in a horizontal position, the switch is in the off state.
The motion and position sensing switch is comprised of an electrically conductive enclosure 11 having a truncated cone-shaped cavity 12. It will be understood by those knowledgeable in this art that cavity 12 may have other 10 shapes as well. Enclosure 11 and cavity 12 are capped by means of a plate 13 having a conductive circuit 14, electrically isolated from enclosure 11. Plate 13 is secured onto enclosure 11 by means of fasteners 15 which can consist of self-tapping screws and the like. A conductive ball 16 is used as a contact making element between conductive enclosure 11 and conductive circuit 14.
A pair of conductors 17a and 17b can be connected to a suitable detecting circuit (not shown) adapted to monitor the change of state of switch 10. The interior edge 18 of cavity 12 makes an angle of 30 from a vertical axis. When switch 10 pivots about the horizontal axis to an angle greater than 60 from thevertical axis, conductive ball 16 rolls to the outer edge 19 of cavity 12, thereby 20 allowing contact to be made between enclosure 11 and conductive circuit 14. (See FIGURE 2). In this position, switch 10 now turns to an active state since current is allowed to flow from enclosure 11 to conductive circuit 14 and to a detectingcircuit via conductor 17a and 17b.
Referring now to FIGURE 3, we have shown a top view of the conductive 25 circuit shown at reference numeral 14 of FIGURES 1 and 2. Conductive circuit 14 is comprised of a gold-plated circuit etched on a nonconductive surface 21. In the present embodiment, conductive circuit 14 forms two separate electrical conductive regions. These regions are comprised of a first set of conductive lines or fingers 22 extending outwardly from a central conductive region 23. Each 30 finger is positioned radially in spaced relationship. A second set of lines or fingers 24 extend inwardly from a peripheral conductive ring 25 located outwardly from the first set of lines 22. The second set of lines 24 are positioned radially in spaced relationship adjacent to the first set of lines 22. A separate conductiveline 26 is used to connect conductive ring 25 to a central conductive region 27 35 Iying adjacent to conductive region 23. The first and second set of lines areelectrically isolated from one another. Conductive regions 23 and 27 are individually connected to a detecting circuit (not shown) by means of conductors 17a and 17b, respectively.
Conductive circuit 14 allows switch 10 to provide, while in the active state, three possible electrical state changes. For example, conductive ball 16 can make electrical contact between enclosure 11 and conductive fingers 22, between enclosure 11 and conductive fingers 24 and between enclosure 11 and conductive 5 fingers 22 and 24. That is, the conductive ball 16 can make contact with fingers 22, 24 or both.
Similarly, conductive circuit 14 could be designed with a single set of conductive fingers separated by nonconductive fingers, thereby allowing a detecting circuit to detect a change of state of the motion sensing switch. It will 10 be understood by those knowledgeable in this art that other circuit designs can be used to arrive at the same results without departing from the scope of the invention.
Referring now to FIGURE 4, a block diagram of a motion sensor circuit is depicted at reference numeral 30. The motion sensing switch is depicted by 15 circuit 31 defined by the dotted line. Switch 32 represents the opening and closing of electrical contact made by the conductive ball between enclosure 11 and fingers 22. Conductor 17a leads from switch 31 to a transistor switching circuit 33. Enclosure 11 is connected to ground by means of conductor 34 which is not shown in FIGURES 1 and 2 for sake of clarity. Switch 35 represents the 20 opening and closing of electrical contact made by conductive ball 16 between enclosure 11 and fingers 24. Conductor 17b connects conductive region 27 to transistor switching circuit 36.
The collectors 37 and 38 from the transistor switching circuits 33 and 36 are connected to a buffer circuit 39. The output of the buffer circuit is then 25 connected to a microprocessor 40.
The microprocessor 40 senses the two switch inputs. Whenever the microprocessor detects a change of state created by switch 32 and 35, i.e., switch 32 open, switch 35 closed, switch 32 closed, switch 35 open or switch 32 and 35 closed, an internal timer (not shown) is reset and activated. However, if30 the timer reaches a preset value before a change of state is detected, then an alarm is initiated. This would occur, for example, if conductive ball 16 remained motionless making contact between enclosure 11 and conductive circuit 14.
In another embodiment, motion sensing switch 10 could be made of a non-conductive enclosure and provided with a conductive region near the outer edge of 35 the cavity, such that when the contact making element moves to the outer edge of the cavity, contact is made between ground and the conductive circuit.
13~844 Referring now to FIGURE 5, we have shown at reference numeral 45 a sectional view of a motion sensor according to another embodiment of the presentinvention. The sensor is comprised of an enclosure 46 having an open end shown generally at reference numeral 47 which is covered by means of a base 48 and 5 secured therein by means of a channel 49 formed by a pair of ridges 50 and 51.Base 48 is provided with a pressure sensitive electrical sensor 52 which can consists of a piezoelectric element. A motion sensitive weight, such as ball bearing 53, is retained within enclosure 46 and can freely move therein. Leads 54 and 55 are connected to a detection circuit adapted to monitor any electrical 10 impulses generated which are indicative of the motion of ball bearing 53 on base 48.
Such a sensor, because of its ruggedness and simplicity, is well suited for applications in the logging industry.
Referring now to FIGURE 6, we have shown a block diagram of one 15 embodiment of a personal security communication system formed in accordance with the present invention. While the system illustrated in FIGURE 6 and discussed below utilizes a position/motion sensor 61, it is to be understood that the system may utilize other types of sensing devices, such as a gas detector or a heart monitor, for example. Furthermore, the system may utilize more than one 20 sensing device or no sensing device.
In this system, the microcomputer 60 is the heart of the system. ln the particular embodiment illustrated in FIGURE 6, the microcomputer 60 is responsible for monitoring the status of the user by means of the position/motion sensor 61 or manual input 62. Manual input 62 is basically comprised of a switch25 which is activatable by the user when an alarm condition exists. If, however, the user has become disabled, the position and motion sensor 61 can detect the existence of an alarm condition. If an alarm condition exists, microcomputer 60 will format a digital data message to be transmitted through a radio transmitter 63 via antenna 64 to other units in the system or to a central station.
30 When this condition exists, microcomputer 60 would activate signaling means such as beeper 65 and/or light emitting diode 66 forming part of each unit. A digitalradio receiver 67 and receiving antenna 68 are provided with each unit. The microcomputer 60 listens to the signal provided by radio receiver 67 for messages coming from other units or from a base station. Computer 60 controls the 35 beeper 65 and light emitting diode 66 to display the status of the system.
The microcomputer 60 may consist of, but is not limited to, an Intel 8051 microcontroller and external, single component EPROM memory chip. The radio transmitter 63 and receiver 67 are capable of transmitting and receiving a digital data message. The on/off keying and modulation of the transmitter 63 can be controlled by microcomputer 60. The receiver 67 will normally be on, and turned off during transmission. The power supply 69 is used to provide power to radio 5 transmitter 63, receiver 67, microcomputer 60, beeper 65 and light emitting diode 66. The power supply can consist of a Nicad rechargeable battery pack.
The system can be enclosed in a small housing and belt mounted.
The system can be configured with two units operating in a buddy system, where each unit monitors the other's status or in a group system, where the status 10 of all the working units is monitored frorn a base station.
As indicated above, different modes of operation are possible using the present system. For example, in a nonpolling network, each user would carry a unit having only the transmitter rather than both transmitter and receiver. The transmitter would be activated upon occurrence of an alarm condition. A signal 15 would then be transmitted to a base station which would monitor all transmissions from each unit in the field. The information flow chart for both the base station and a unit is shown in FIGURES 7 and 8, respectively.
The communication system may also operate in a polling network, wherein each unit worn by a worker in a group of workers is provided with a transmitter 20 and a receiver. A base station will continuously poll the status of each individual. For example, the base station will poll a first portable unit and await a response prior to polling a second portable unit. If no response is received after a specified time, the alarm will be activated. The information flow chart for the base station is shown in FIGURE 9. The information flow chart for the portable 25 units is depicted in FIGURE 10.
As indicated above, the personal security communication system may also be configured as a buddy system. In a buddy system configuration, two portable units work as a pair. The portable units are bilateral, such that each unit includes areceiver and transmitter, preferably, in the form of a transceiver. As will become 30 better understood from the following discussion, each portable unit transmitsencoded status information in the form of a data message, such as a digital datamessage, for example, to the other unit in the pair. More specifically, the portable units transmit encoded status information as a radio frequency carrier signal modulated with data messages. The data message is transmitted 35 continuously at regular intervals. As will also become better understood from the following discussion, the encoded status information in each message includes a transmitting unit identification number and alarm condition information. The 13018~4 other unit of the pair receives the data message and alerts a worker wearing thereceiving unit if the alarm condition information indicates an emergency alarm condition exists at the transmitting unit. The receiving unit also alerts the worker of an out-of-range or malfunctioning transmitting or receiving unit when a data 5 message is not received for a predetermined period of time (i.e., a communication failure alarm).
FIGURE 11 is a block diagram of a preferred embodiment of the personal security communication system configured as a buddy system. A first portable unit 100 and a second portable unit 200 operate as a unit pair 98. The first 10 portable unit 100 comprises: one or more sensors 102, a manual alarm switch 104;
a power supply 106; a microcomputer 108; a digital transceiver 110; an alarm 112;
an ON-OFF-REST switch 116; and, an antenna 114. The power supply 106 provides power to the microcomputer 108, transceiver 110, and the alarm 112 via line 124. The microcomputer 108 receives sensor input signals from the 15 sensors 102 via line 120 and a manual alarm input signal from the manual alarm switch 10~ via line 122. The microcomputer 108 produces encoded status information on line 126. The transceiver 110 receives the encoded status information and transmits a digital data message to the second portable unit 200via the antenna 114.
The ON-OFF-REST switch 116 (hereinafter referred to as switch 116) is connected to the microprocessor 108 via line 132. The switch 116 is preferably athree position switch. When the switch is in the OFF position, the unit 100 is off and cannot receive or transmit data. When the switch 116 is in the ON position, the unit 100 operates in a normal manner, which is discussed below. As will 25 become better understood from the following discussion, when the switch 116 is in the REST position at least one of the sensors 102 is disabled. When the switch 116 is in the REST position the unit 100 continues to operate as if the switch 116 was in the ON position, with the exception of the sensors 102 that are disabled.
The second portable unit 200 is identical to the first portable unit 100 30 discussed above. More specifically, the second portable unit 200 comprises: one or more sensors 202; a manual alarm switch 204; a power supply 206; a microcomputer 208; a digital transceiver 210; an alarm 212; an ON-OFF-REST
switch 216; and, an antenna 214. The power supply 206 supplies power to the microcomputer 208, the transceiver 210 and the alarm 212 via line 224. The 35 microcomputer 208 receives sensor input signals from the sensors 202 via line 220 and a manual alarm input signal from the manual alarm switch via line 222. The microcomputer 208 produces encoded status information on line 226. The 130~844 g transceiver 210 receives the encoded status information and transmits a digital data message to the first portable- unit 100 via antenna 214.
The ON-OFF-REST switch 216 (hereinafter referred to as switch 216) is connected to the microprocessor 208 via line 232. The switch 216 is preferably a5 three position switch that controls the unit 200 in a manner similar to that discussed above for the switch 116 and the unit 1û0.
Microcomputers 108 and 208 are preferably identical to the microcomputer 60 discussed above and illustrated in FIGURE 6. Likewise, the power supplies 106 and 206 are, preferably, identical to the power supply 69 10 (FIGURE 6) and the manual alarm switches 104 and 204 are, preferably, identical to the manual input 62 (also FIGURE 6). The digital transceivers 110 and 210 are, preferably, conventional digital transceivers and operate substantially the same as the digital radio transmitter 63 and receiver 67 discussed above and illustrated in FIGURE 6. The alarms 112 and 212, preferably, include visual and audible alarms 15 substantially the same as the beeper 65 and LED 66 also noted above and illustrated in FIGURE 6. Accordingly, these elements of the present invention are not discussed below in further detail.
The sensors 102 and 202 may include a motion sensor identical to the motion sensor 45 discussed above and illustrated in FIGURE 5. The sensors 102 and 202 20 may also include a motion and position sensing switch identical to the switch 10 discussed above and illustrated in FIGUl~ES 1-3. In any event, the motion sensorand/or the motion and position sensing switch may, in accordance with an actual working embodiment of the present invention, be disabled by activating the switches 116 and 216. Preferably, other functions of the units 100 and 200 are 25 unaffected by the switches 116 and 216. As noted above, the sensors 102 and 202 may also include other types of sensing devices, such as a gas detector or a heart monitor, for example. Furthermore, the sensors 102 and 202 may include multiple sensing devices. The units 100 and 200 may also function without sensors 102 and202, such that microcomputers 108 and 208 receive only the input signals from the 30 manual alarm switches 104 and 204, respectively.
The digital data message transmitted by the first portable unit 100 is received by the transceiver 210 in the second portable unit 200 via the antenna 214. The microcomputer 208 receives the encoded status information via line 228. The microcomputer 208 decodes the status information and, if 35 appropriate, sends an alarm signal to the alarm 212 via line 230. Similarly, the first portable unit 100 receives a digital data message from the second portableunit 200 via the antenna 114. The microcomputer 108 receives the encoded status ~:~018~
information on line 128 and decodes the status information. If appropriate, the microcornputer 108 sends an alarm signal to the alarm 112 via line 130. As will become better understood from the following discussion, the microcomputers 108 and 208, preferably, produce different alarm signals for different alarm conditions 5 indicated by the status information. Accordingly, the alarms 112 and 212, preferably, produce different alarms related to the different alarm signals.
If an emergency alarm condition exists, which is determined by the input signals on lines 120 and 122 for the unit 100, and on lines 220 and 222 for the unit 200, the microcomputer 108 and 208 also send alarm signals to their 10 respective alarms 112 and 212. For example, if a user activates the manual alarm switch 104 in the first portable unit 100~ the microcomputer 108 encodes this manual alarm signal into a digital data message that is transmitted to the second portable unit 200 and an alarm is produced at the second portable unit 200. The microcomputer 108 in the first portable unit 100 also sends an alarm signal to the 15 alarm 112 in the first portable unit 100 via line 130. The alarm in the firstportable unit 100 informs the worker that he has initiated an emergency alarm.
The microcomputer 108 also monitors the power supply 106 and alerts the worker wearing the first portable unit 100 if a low power supply volta~e exists. More specifically, the microcomputer 108 produces an alarm signal on line 130 if a low 20 power supply voltage is detected on line 124. Likewise, the microcomputer 208 in the second portable unit 200 monitors the power supply voltage on line 224 and produces an alarm signal on line 230 if a low power supply voltage is detected.
Preferably, the units 100 and 200 permit false alarms to be cleared before they are transmitted to the other unit. A delay (e.g., 5 seconds) permits false 25 alarm input signals to be cleared by a worker wearing the transmitting unit. For example, if a worker wearing unit 100 inadvertently activates the manual alarm switch 104, an alarrn signal will be produced on line 122. The unit 100 will delay (for an appropriate period of time) encoding the signal and transmitting an emergency alarm condition in the data message to allow the worker to clear the 30 false alarm. The false alarm may be cleared by turning the unit 100 off (via the switch 116) and then turning the unit 100 back on. The other unit 200 works similarly.
FIGURE 12 is a perspective view of one preferred embodiment of the first portable unit 100 discussed above. The second portable unit 200 is not depicted in 35 FIGURE 12 for purposes of clarity. Accordingly, it is to be understood that the various features illustrated in FIGURE 12 and discussed below for the first portable unit 100 are identical to the respective features of the second portable 130~844 unit 200. The first portable unit 100 has a housing 150 that is, preferably, made of a rugged material, such as a mgh impact,-shock resistant plastic, for-example.
However, other suitable materials may also be used. The antenna 114, the manual alarm switch 104, and the ON-OFF-REST switch 116, preferably, extend from a 5 top surface 154 of the unit 100. A guard 152, preferably, extends above the top surface 154 and at least partially encloses the antenna 114 and the switches 104and 116. A belt loop 156 is formed by a bracket 158 attached to, or formed by, the housing 150. A worker's belt 160 passes through the belt loop 156, thus, making it easy for the worker to wear the first portable unit 100 while performing 10 a job task. The bracket 158 may be made of a rigid material similar to the housing 150 or may be made of another type of material, such as flexible strapping material, for example.
FIGURES 13 and 14 are information flow charts for the buddy system configuration of the personal security communication system illustrated in 15 FIGURE 11 and discussed above. More specifically, the flow charts represent the functional steps of a program that controls the microcomputers 108 and 208. The information flow charts illustrated in FIGURES 13 and 14 are identical for both units 100 and 200 in the unit pair 98. Accordingly, for purpcses of clarity, theflow charts illustrated in FIGURES 13 and 14 are described below for the first 20 portable unit 100.
The system becomes operational when one or both of the units 100 or 200 in the buddy system are turned on. The start block at the top of FIGURE 13 represents the first portable unit 100 being turned on. Once the unit 100 has been turned on, the program instructs the microcomputer 108 to initialize various 25 timers and the status information associated with the unit 100. More specifically, a motion timer, a transmit timer and a message timer are initialized. As will become better understood from the following discussion, the transmit timer regulates the time interval between transmissions of digital data messages to the other unit 200. The motion timer monitors the time interval during which no 30 movement is detected by the first portable unit 100. The message timer monitors the time interval between consecutive data messages transmitted by the other unit 200. Also during this step, the status information is initialized, so that, for example, any prior emergency alarm conditions are cleared. After the initialization step, each of the timers is incremented and the program proceeds to 35 the next step.
Once the timers have been incremented, the program instructs the microcomputer 108 to perform a power supply low voltage test. As noted above, 130~il44 if the microcomputer 108 determines that the power supply voltage is low (i.e., below a predetermined threshold level) an alarm signal is applied to the alarm 112 in the first portable unit 100. In accordance with the preferred ernbodiment of the invention, this power supply low voltage alarm is not transmitted to the 5 second portable unit 200. During this step the program also instructs the microcomputer 108 to determine whether a manual alarm has been initiated. If the microcomputer 108 determines that a manual alarm has been initiated (i.e., detects a manual alarm signal on line 122~, the status information is updated toreflect the emergency alarm condition.
Next, and in accordance with a preferred embodiment of the invention, the program instructs the microcomputer to determine whether there has been movement by the user or whether a lack-of-motion alarm signal should be produced. More specifically, the microcomputer 108 receives motion sensor signals from a motion sensor, such as the motion sensor 45 illustrated in 15 Fl~:URE 5, for example. The motion sensor 45 produces a motion sensor signal each time movement of the worker is detected. When a motion sensor signal is received by the microcomputer 108, the motion timer is cleared and the status information updated accordingly. If the microcomputer 108 does not sense a motion sensor signal, the program then determines whether the time interval 20 measured by the motion timer has exceeded a maximum allowable time limit (i.e., a predetermined time interval, such as one minute, for example). If the time interval measured by the motion timer exceeds the maximum allowable time limit, a lack-of-motion alarm condition exists. As a result, the status information is updated to include emergency alarm information that reflects the lack-of-25 motion alarm condition. Once the status information has been updated, theprogram proceeds to the next step, which is discussed below. If the microcomputer 108 does not sense a motion sensor signal and the time interval measured by the motion timer does not exceed the maximum allowable time limit, the program bypasses the status information update step and proceeds directly to30 the next step.
Next, the program determines whether it is time to transmit the current status information as a data message to the second portable unit 200. More specifically, if the time interval measured by the transmit timer equals or exceeds a predetermined time limit, such as, four and one-half seconds, for example, the35 program clears the transmit timer and transmits the current status information as a data message to the second portable unit 200. Once the data message has been transmitted, the program returns to increment the cleared transmit timer and the ~301844 and message and motion timers (FIGURE 13). If the program determines that it is not time to transmit the status information, that iS7 if the time interval measured by the transmit timer since the last transmitted message is less than the predetermined time limit, the first portable unit 100 does not transmit the status 5 information as a data message and the program proceeds to the next step.
Turning to FIGURE 14J once the program has determined it is not yet time to transmit the data message, the program determines whether the first portable unit 100 has received a digital data message from the second portable unit 200.
As noted above, the data message transmitted by the second portable unit 200 10 includes encoded status information associated with the second portable unit 200. More specifically, the encoded status information from unit 200 includes an identification number for the second portable unit 200 and alarm condition information associated with the second portable unit 200. If a data message has not been received by the first portable unit 100, the program determines whether15 it has been too long since the last data message was received. More specifically, if the time interval monitored by the message timer does not exceed a maximum allowable time limit (such as two and one-half minutes, for example), the program returns to increment the timers (FIGURE 13). If the time interval monitored by the message timer does exceed the maximum allowable time limit, the program 20 instructs the microcomputer 108 to produce an unit out-of-range/unit malfunction alarm signal. The alarm signal is applied to the alarm 112 (FIGURE 11). Once thealarm signal has been produced, the program returns to increment the timers (FIGURE 13).
If a data message has been received by the first portable unit 100, the 25 program determines whether the received message was transmitted from the second portable unit 200 or from some other unit. Thls is done by the first portable unit 100 when it decodes the data message and compares the unit identification number in the received data message with the identification number of the other unit in the pair (i.e., the second portable unit 200). If the 30 identification number i9 not the same as the second portable unit identification number, then the message was transmitted from another unit and the message is ignored by the first portable unit 100. In this situation the program returns toincrement the timers (FIGURE 13). If the program determines the received message is from the second portable unit 200 (i.e., the received data message 35 contains the second portable unit identification number), the message timer in unit 100 is cleared and the program determines whether the data message includedemergency alarm information. If emergency alarm information was included in 130~844 the received data message, the program instructs the microcomputer 108 to produce-an emergency alarm signal.- The-emergen~y alarrn signal- is applied to the-alarm 112 (FIGURE 11). Next, the program returns to increment the timers (FIGURE 13). If the program determines that emergency alarm information was 5 not included in the received data message, the program returns to increment the timers (FIGURE 13). The program steps are repeated in the manner illustrated in FIGURES 13 and 14 and discussed above until the first portable unit 100 is turned off.
As noted above, one physical embodiment of the present invention includes a 10 rest feature that disables at least one of the sensors 102 illustrated in FIGURE 11 and discussed above (such as the motion sensor d~5, for example). More specifically, if the first portable unit 100 is placed in a rest mode (i.e., if the switch 116 is placed in the REST position, FIGURE 11), the first portable unit 100 will continue to update status information and transmit data messages to the 15 second portable unit 200 and receive data messages from the second portable unit 200. However, while in the rest mode, the first portable unit 100 will not transmit emergency alarm information indicating a lack-of-motion alarm condition to the second portable unit 200. Thus, with the first portable unit 100 in the rest mode, the worker wearing the first portable unit 100 may stop working 20 (i.e., rest) and not send false lack-of-motion alarm signals to the second portable unit 200 while continuing to monitor the second portable unit 200.
As can be readily appreciated from the foregoing description, the invention provides a personal security communication system. While a preferred embodiment of the invention has been illustrated and described herein, it is to be 25 understood that, within the scope of the appended claims, various changes can be made. For example, more than two units can be configured to operate together in a buddy systern. Also, the units in a buddy system rnay communicate with a base station, in addition to communicating with each other. Furthermore, processors other than the microcomputers discussed above may be used. Hence, the 30 invention may be practiced otherwise than as specifically described herein.
Claims (31)
1. A personal security communication system configured to operate as a buddy system, said system comprising: (a) a first portable unit for producing a first status signal and receiving a second status signal, said first portable unit transmitting said first status signal as a radio frequency carrier signal modulated with data messages, said first portable unit producing an alarm when said first status signal includes emergency alarm information, and said first portable unit also producing an alarm when said second status signal includes emergency alarm information, said first portable unit further producing an alarm when said second status signal is not received for a predetermined period of time; and , (b) a second portable unit for producing said second status signal and receiving said first status signal, said second portable unit transmitting said second status signal as a radio frequency carrier signal modulated with data messages, said second portable unit producing an alarm when said first status signal includes emergency alarm condition information and said second portable unit also producing an alarm when said second status signal includes emergency alarm condition information, said second portable unit further producing an alarm when said first status signal is not received for a predetermined period of time.
2. The system claimed in claim 1, wherein said first portable unit comprises, (a) first signaling means; (b) first receiving means for receiving said second status signal; (c) first processing means for receiving and encoding signal information from said first signaling means and producing said first status signal indicative of said signal information and for receiving and decoding said second status signal; (d) first transmitting means for transmitting said first status signal as a first data message;
and, (e) first alarm means for producing an alarm when said first status signal includes said emergency alarm information and for producing an alarm when said second status signal includes said emergency alarm information, said first alarm means further producing an alarm when said second status signal is not received for said predetermined period of time.
and, (e) first alarm means for producing an alarm when said first status signal includes said emergency alarm information and for producing an alarm when said second status signal includes said emergency alarm information, said first alarm means further producing an alarm when said second status signal is not received for said predetermined period of time.
3. The system claimed in claim 2, wherein said second portable unit comprises: (a) second signaling means; (b) second receiving means for receiving said first status signal; (c) second processing means for receiving and encoding signal information from said second signaling means and producing said second status signal indicative of said signal information and for receiving and decoding said first status signal; (d) second transmitting means for transmitting said second status signal as a second data message; and, (e) second alarm means for producing an alarm when said first status signal includes said emergency alarm information and for producing an alarm when said second status signal includes said emergency alarm information, said second alarm means further producing an alarm when said first status signal is not received for said predetermined period of time.
4. The system claimed in claim 3, wherein said first signaling means of said first portable unit comprises a first manual alarm switch that produces a first manual alarm signal when activated, said first manual alarm signal causing said first processing means to produce said first status information signal including emergency alarm information related to said first manual alarm signal, and wherein said second signaling means of said second portable unit comprises a second manual alarm switch that produces a second manual alarm signal when activated, said second manual alarm signal causing said second processing means to produce said second status information signal including emergency alarm information related to said second manual alarm signal.
5. The system claimed in claim 4, wherein said first signaling means of said first portable unit further comprises a first motion sensor that senses motion of said first portable unit, produces first motion sensor signals responsive to the motion of said first portable unit and provides said first motion sensor signals to said first processing means in said first portable unit, and wherein said second signaling means of said second portable unit further comprises a second motion sensor that senses motion of said second portable unit, produces second motion sensor signals responsive to the motion of said second portable unit and provides said second motion sensor signals to said processing means in said second portable unit.
6. The system claimed in claim 5, wherein said first processing means of said first portable unit comprises first transmit timing means for controlling the transmission of said first status signal such that said first status signal is transmitted at regular intervals determined by said first transmit timing means, and wherein said second processing means of said second portable unit comprises second transmit timing means for controlling the transmission of said second status signal, such that said second status signal is transmitted at regular intervals determined by said second transmit timing means.
7. The system claimed in claim 6, wherein said first processing means of said first portable unit further comprises first motion timing means for liming intervals between consecutive first motion sensor signals produced by said first motion sensor in said first portable unit, said first portable unit producing said first data message including emergency alarm information indicating lack of motion of said first portable unit when said interval between said consecutive first motion sensor signals exceeds a predetermined time interval, and wherein said second processing means of said second portable unit further comprises second motion timing means for timing intervals between consecutive second motion sensor signals produced by said second motion sensor in said second portable unit, said second portable unit producing said second data message including emergency alarm information indicating lack of motion of said second portable unit when said interval between said consecutive second motion sensor signals exceeds a predetermined time interval.
8. The system claimed in claim 7, wherein said first processing means of said first portable unit further comprises first message timing means for timing intervals between consecutive second data messages transmitted by said second portable unit, said first portable unit producing an alarm indicating a communication failure between said first and second portable units when said interval between said consecutive second data messages exceeds a predetermined time interval, and wherein said second processing means of said second portable unit further comprises second message timing means for timing intervals between consecutive first data messages transmitted by said first portable unit, said second portable unit producing an alarm indicating a communication failure between said first and second portable units when said interval between said consecutive first data messages exceeds a predetermined time interval.
9. The system claimed in claim 8, wherein said first portable unit includes a first switch that disables said first motion sensor and, wherein said second portable unit includes a second switch that disables said second motion sensor.
10. The system claimed in claim 9, wherein said first and second alarm means include both visual and audible alarm devices.
11. The system claimed in claim 1, wherein said first and second portable units each include a self-contained power supply.
12. The system claimed in claim 11, wherein said first and second portable units may be mounted on belts worn by workers using said first and second portable units.
13. A portable unit for use in a personal security communication system comprising: a housing adapted to be worn by an individual; a signaling unit integral with said housing including a manually actuatable switch for producing an alarm signal and a motion sensor including an enclosure having an open end, a base covering said open end, a pressure sensitive electrical means on said base facing said enclosure and a mass in said enclosure adapted to move freely therein when said housing is in motion such that movement over said sensing means results in the production of a motion signal; a processing means connected to said signaling unit for receiving said alarm signal and said motion signal and for producing status information signals of said received signals including a processor alarm signal which is produced when said manual alarm signal is produced or when said motion signal indicates said housing has been motionless for a selected amount of time; a transmitting means connected to said processing means for receiving said status information signals and for transmitting said status information signals as data messages;
an alarm connected to said processing means for receiving said processor alarm signal and actuatable in response to receiving said processor alarm signal; and, a power supply coupled to supply power to said processing means, said transmitting means, and said alarm.
an alarm connected to said processing means for receiving said processor alarm signal and actuatable in response to receiving said processor alarm signal; and, a power supply coupled to supply power to said processing means, said transmitting means, and said alarm.
14. The portable unit claimed in claim 13, wherein said pressure sensitive electrical sensing means comprises a piezoelectric element and said mass comprises a ball bearing.
15. A portable unit for use in a personal security communication system comprising a housing adapted to be worn by an individual; a signaling unit integral with said housing including a manually actuatable switch for producing an alarm signal and a motion sensor for generating a motion signal whenever said housing is in motion; a processing means connected to said signaling unit for receiving said alarm signal and said motion signal and for producing status information signals of said received signals including a processor alarm signal which is asserted when said manual alarm signal is asserted or when said motion signal indicates said housing has been motionless for a selected amount of time; a transceiver connected to said processing means transmitting and receiving status information signals from and to said processor means, wherein said status information signals are transmitted and received in the form of data messages; an alarm connected to said processing means for receiving said processor alarm signal and actuatable in response to receiving said processor alarm signal; and, a power supply coupled to supply power to said processing means, said transmitting means, and said alarm.
16. The portable unit claimed in claim 15 wherein said processor means is a microcomputer.
17. A personal safety unit comprising: a housing adapted to be worn by an individual; a motion detector integrally attached to said housing including: a motion sensor including two mechanical elements arranged such that one said mechanical element moves in and out of contact with the other said mechanical element when said housing is in motion and such that said sensor produces a motion signal indicative of contact status of said mechanical elements; and a detect circuit coupled to said motion sensor for receiving said motion signal, monitoring same, and producing an alarm signal when said housing is motionless for a selected amount of time; an alarm device integral with said housing and connected to receive said alarm signal and responding to said alarm signal by producing an alarm; and a transmitter integrally attached to said housing for receiving said alarm signal and, in response to an alarm signal, transmitting a signal indicating said alarm signal was produced.
18. The personal safety unit of claim 17, wherein said motion sensor includes a capped enclosure integral with said housing, a mass disposed in said enclosure and adapted for free movement therein, and a sensing means integral with said enclosure for producing a signal representative of the movement of said mass.
19. The personal safety unit of claim 18, wherein said sensing means comprises a piezoelectric element attached to said enclosure and said mass is a ball bearing.
20. The personal safety unit of claim 19, wherein said detect circuit includes a processor for monitoring said motion signal and producing said alarm signal when said housing has been motionless for a selected amount of time.
21. The personal safety unit of claim 17, wherein said detect circuit includes a processor for monitoring said motion signal and producing said alarm signal when said housing has been motionless for a selected amount of time.
22. The personal safety unit of claim 21, further including a receiver for receiving incoming status information, and wherein said processor is connected to said receiver for receiving said incoming status information and, in response to selected incoming status information, produces an alarm signal.
23. The personal safety unit of claim 17, wherein, said motion sensor is responsive to said housing motion such that said sensor produces a first motion signal when said housing is in a first position and negates said first position signal when said housing is in a second position; and said detect circuit monitors said sensor signal and, when said first motion signal is produced for more than said selected length of time, produces said alarm signal and, when said first position signal is negated for more than said selected length of time, produces said alarm signal.
24. The personal safety unit of claim 23, wherein said motion switch comprises an enclosure forming a cavity, said enclosure further having two spaced-apart conductive elements and a conductive mass in said cavity adapted to move therein such that when said housing is in said first position said conductive element established an electrical connection between said enclosure conductive regions, and when said housing is in said second position said conductive element is spaced from said enclosure conductive regions so as to break electrical connections established therebetween.
25. The personal safety unit of claim 23, wherein said detect circuit includes a processor for monitoring said motion signal and asserting said alarm signal when said housing has been motionless for a selected amount of time.
26. A personal safety unit comprising, a housing adapted to be worn by an individual; a motion detector integrally attached to said housing including: a motion sensor including two mechanical elements arranged such that one said mechanical element moves in and out of contact with the other said mechanical element when said housing is in motion and such that said sensor produces a motion signal indicative of contact status of said mechanical elements; and a detect circuit coupled to said motion sensor for receiving said motion signal, monitoring same, and producing an alarm signal when said housing is motionless for a selected amount of time; an alarm device integral with said housing and connected to receive said alarm signal and responding to said alarm signal by producing an alarm.
27. A personal safety unit comprising: a housing adapted to be worn by an individual; a motion detector integrally attached to said housing including: a motion sensor including two mechanical elements arranged such that one said mechanical element moves in and out of contact with the other said mechanical element when said housing is in motion and such that said sensor produces a motion signal indicative of contact status of said mechanical elements; and a detect circuit coupled to said motion sensor for receiving said motion signal, monitoring same, and producing an alarm signal when said housing is motionless for a selected amount of time; and a transmitter integrally attached to said housing for receiving said alarm signal and, in response to an alarm signal, transmitting a signal indicating said alarm signal was produced.
28. The personal safety unit of claim 27, further including an alarm integrally attached to said housing connected to receive said detect circuit alarm signal and responding to said alarm signal by producing an alarm.
29. A motion sensor adapted to indicate motion and lack of motion, comprising, an enclosure with an open end; a base for covering said open end; pressure sensitive electrical sensing means on said base, facing said enclosure and motion sensitive weight means in said enclosure adapted to move freely in said enclosure such that when said weight means move over said sensing means, an electrical signal indicative of the motion of said weight means over said sensing means can be detected.
30. A motion sensor as defined in claim 29 wherein said pressure sensitive electrical sensing means comprises a piezoelectric element.
31. A motion sensor as defined in claim 30 wherein said weight means comprises a ball bearing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US326,716 | 1981-12-12 | ||
| US07/326,716 US4978946A (en) | 1987-08-13 | 1989-03-21 | Personal security communication system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1301844C true CA1301844C (en) | 1992-05-26 |
Family
ID=23273377
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000596088A Expired - Lifetime CA1301844C (en) | 1989-03-21 | 1989-04-07 | Personal security communication system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1301844C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9147330B2 (en) | 2009-08-14 | 2015-09-29 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
| AU2013254930B2 (en) * | 2009-08-14 | 2015-10-15 | Accenture Global Services Limited | System for relative positioning of access points in a real time locating system |
-
1989
- 1989-04-07 CA CA000596088A patent/CA1301844C/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9147330B2 (en) | 2009-08-14 | 2015-09-29 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
| AU2013254930B2 (en) * | 2009-08-14 | 2015-10-15 | Accenture Global Services Limited | System for relative positioning of access points in a real time locating system |
| US9189944B2 (en) | 2009-08-14 | 2015-11-17 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
| US9235974B2 (en) | 2009-08-14 | 2016-01-12 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
| US9754472B2 (en) | 2009-08-14 | 2017-09-05 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
| US10210738B2 (en) | 2009-08-14 | 2019-02-19 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
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