JPH09161177A - Position detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detection system with which the position of retrieving object can be specified with high accuracy by a little base stations to be installed. SOLUTION: Radio waves transmitted from a hand set 11 are received at three base stations 12A to 12C, and a computer 15 of center station 13 specifies the position of hand set 11 as the retrieving object by respectively calculating the distances from the relevant hand set 11 to the respective base stations 12A to 12C from the time required for reaching the radio waves from the hand set 11, for which there is a retrieval request from a base unit 14, to the respective base stations 12A to 12C. The found position information is transmitted from the center station 13 to the base unit 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting system for specifying the position of a slave unit by the time difference until the radio wave transmitted from the slave unit is received by a base station.

[0002]

2. Description of the Related Art For example, an amusement park or a zoo, which is crowded with people,
As a search system for lost children at event venues,
A large number of base stations 1A, 1B, ... Are installed in advance, the base stations 1A, 1B, ... Receive radio waves transmitted from a transmitter 2 held by a child, and compare the received radio field intensities. Then, there is a position detection system called a zone detection method, which determines that there is a lost child in the zone of the base station having the strongest radio field intensity (see FIG. 6). In the example of the figure, since the transmitter 2 is the closest to the base station 1B and the radio field intensity received by the base station 1B is the strongest, the transmitter 2 (that is,
(Lost child) is present in zone 3 of base station 1B.

[0003]

However, in such a conventional position detection system, a radio wave transmission source (transmission source) is generated in the vicinity of which base station 1 from the radio wave intensity data between the base station 1 and the transmitter 2. Since it is a system that searches for the presence of the device 2), it is necessary to install more base stations 1 in order to improve the accuracy of the search, that is, the accuracy of specifying the position. However, the addition of the base station 1 is not always an effective method because there are restrictions on location, and there are problems such as an increase in installation cost and deterioration of aesthetics.

The present invention has been made in view of the above-mentioned problems in the conventional zone detection method. Instead of the zone detection method, it is possible to specify the position to be searched with high accuracy by using a small number of base stations. It is an object of the present invention to provide a position detection system capable of

[0005]

In order to achieve the above object, the invention according to claim 1 is a slave unit for transmitting a signal including a current time by radio waves at a predetermined time interval, and a slave unit for receiving the signal from the slave unit. At least three or more base stations that transmit a signal by adding the reception time and its own identification code to the signal by radio waves, and the slave unit and the base stations based on the information received from the base stations. And a center station that specifies the position of the slave unit.

In the present invention, the slave unit always transmits a signal including the current time by radio waves at a predetermined time interval. Each time the base station receives a radio wave from the slave unit, it transmits a signal obtained by adding the reception time and its own identification code to the signal received from the slave unit to the center station via the radio wave. The center station calculates the distance between the child device and each base station based on the information received from each base station, and specifies the position of the child device. That is, the arrival time of the radio wave from the handset to each base station is calculated from the transmission time of the handset and the reception time of each base station,
By calculating the distance between the handset and each base station, the position of the handset is specified in relation to each base station. As a result, it is possible to detect the position of the search target to which the child device is attached.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the position information of the slave unit specified by the center station is transmitted to the corresponding master unit. This allows the parent device to confirm the position.

The invention according to claim 3 is characterized in that, in the invention according to claim 2, the master unit outputs a search start command of a corresponding slave unit to the center station by radio waves. As a result, the center station starts the search operation for the slave unit.

The invention according to claim 4 is the above-mentioned claims 1 to 3.
In the invention described in any one of the above items, the center station displays a locus of the position of the slave unit on a screen at a predetermined time interval.

The invention according to claim 5 is the above-mentioned claims 1 to 4.
In the invention described in any one of 1, the slave unit has a unique ID code, and the slave unit to be searched is identified by the ID code. In this case, the child device transmits a signal including the ID code and the current time, and the center station identifies the child device to be searched by the ID code.

The invention according to claim 6 is the above-mentioned claim 2-5.
In the invention described in any one of 1. above, the master device is a mobile phone (including PHS).

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of the position detection system of the present invention. This position detection system includes a handset 11 that constantly emits radio waves at predetermined time intervals,
Three base stations 12A that receive radio waves transmitted from the handset 11 and transmit predetermined information to the center station described later by radio waves,
12B and 12C and the base station 12A-12C based on the information received from each base station 12A-12C.
It is composed of a center station 13 that calculates the distances a, b, and c between each other and specifies the position of the child device 11, and a parent device 14 that corresponds to the child device 11. The center station 13 has a computer 15 capable of high-speed calculation. For example, when applied to a lost child search system in an amusement park, a zoo, an event venue, etc., a parent and a child carry a corresponding parent device 14 and child device 11, respectively. That is, the parent has the parent device 14 and the child has the child device 11.
Further, each of the base stations 12A to 12C is installed in advance at an appropriate place outdoors and / or indoors so as to cover the area to be searched.

It should be noted that the number of base stations 12 to be installed may be three in principle for the reason described later, but four base stations 12 may be provided in order to ensure higher accuracy. However, it is not necessary to install more base stations 12 than that.

Each of the slaves 11 has a built-in clock and has a unique ID code, and includes its own ID code and the current time at predetermined time intervals (for example, every 30 seconds to 1 minute). It is composed of a transmission unit that transmits signals by radio waves. The cordless handset 11 is attached to an object (person, animal, object) whose position needs to be specified in an appropriate form according to the purpose. For example, in the case of a lost child search system, the child device 11 is in the form of, for example, a lost child (pendant) hanging from the neck.

FIG. 2 is a conceptual diagram showing a structure of a signal transmitted from the handset 11. The signal transmitted from the handset 11 is
For example, it consists of a 32-bit address code, an 8-bit control code, and an 8-bit information code. The address code is an ID code such as a classification number, a device number, or a serial number, the control code is a search request code for control, and the information code is an encoded current time of the built-in clock. Wireless communication between the handset 11 and each of the base stations 12A to 12C is performed based on such a format.

Each of the base stations 12A to 12C is composed of a transmission / reception unit (antenna device) capable of transmitting and receiving radio waves, and each has a unique identification code. In addition, each has a built-in clock, and each base station 12A-1
The time of the 2C clock and the clock of the handset 11 are all set accurately in advance. Each base station 12A-12C
Has a function of transmitting a signal obtained by adding the reception time and its own identification code to the signal received from the slave 11 every time it receives a radio wave from the slave 11, to the center station 13 by the radio wave. That is, each of the base stations 12A to 12C is
Information including the ID code of the handset 11 and the radio wave transmission time T, and its own identification code and the radio wave reception time P (Q, R) are wirelessly transmitted to the center station 13 (see FIG. 3).

The center station 13 has a transmission / reception unit (antenna device) capable of transmitting and receiving radio waves, and is further provided with the above-described computer 15 capable of high-speed calculation.
The center station 13 calculates the distances a, b, and c between the handset 11 and the base stations 12A to 12C based on the information received from the base stations 12A to 12C, respectively, and determines the position of the handset 11. It has a function to specify. The computer 15 performs various calculation processes such as distance calculation and position identification.

The principle of position search in the present invention is as follows. FIG. 3 is an explanatory diagram of the principle of the position search method based on the arrival time of radio waves. As described above, the center station 13 receives from each of the base stations 12A to 12C each time the base stations 12A to 12C receive the radio wave from the slave 11, the ID code of the slave 11 and the radio wave transmission time T, and the self station. Since the information including the identification code and the radio wave reception times P, Q, and R are received respectively, the radio wave transmission time T of the handset 11 and the radio wave reception time of the base station 12A for the same radio wave transmitted from the handset 11. The radio wave arrival time tA (= TP) between P and the handset 11 and the base station 12A, the radio wave transmission time T of the handset 11 and the radio wave reception time Q of the base station 12B from the handset 11 and the base station 12B.
From the radio wave arrival time tB (= T−Q), the radio wave transmission time T of the handset 11 and the radio wave reception time R of the base station 12C,
The radio wave arrival times tC (= T-R) between the base station 12C and the base station 12C are calculated, and the respective radio wave arrival times tA, tB, tC are calculated.
By multiplying by the velocity of the radio wave (light velocity), each distance a between the handset 11 and the three base stations 12A to 12C,
b and c can be calculated. Three base stations 12A ~
Since the position of 12C is fixed, the three base stations 1 are determined from the distances a to c between the handset 11 and the base stations 12A to 12C.
The position of the child device 11 can be accurately specified in relation to the positions of 2A to 12C.

Further, the center station 13 has a function of displaying the locus of the position of the slave 11 to be searched on the screen of the computer 15 at predetermined time intervals, for example. That is, the position information of the child device 11 to be searched, which is calculated by the computer 15, is stored in each predetermined area of the built-in memory together with the time information, and it is read at predetermined time intervals and displayed on the screen. An example of the screen display is as shown in FIG. In addition, if the map information of the search area (outdoor and / or indoor) is input to the computer 15 in advance, the locus of the position of the child device 11 can be displayed on a specific map.

The above search operation in the center station 13 (specifically, the computer 15) is performed by a search start command from the master unit 14. Further, the position information of the child device 11 to be searched, which is calculated by the computer 15 of the center station 13, is notified to the corresponding parent device 14 in a predetermined form.

The master unit 14 is composed of a transmission / reception unit capable of transmitting and receiving radio waves, a switch for transmitting a search start / completion command, and an output for outputting position information of the corresponding slave unit 11 received from the center station 13. And a section. The parent device 14 has the same ID code as the corresponding child device 11. The search start / completion command includes the search start / completion request and its ID code. The transmission of the search start command and the search completion command is switched each time one switch is pressed, for example. The output unit is, for example, a display unit and / or
Or, a cordless handset 11 composed of speakers and requesting a search.
The position information of is displayed in the form of a message (such as characters) on the display unit, or a voice is notified from the speaker.

The correspondence relationship between the slaves 11 and the masters 14 is not necessarily limited to one-to-one, and one master 14 can be associated with a plurality of slaves 11.
In this case, the ID code of each child device 11 is registered in the parent device 14 and can be freely selected.

It is also possible to configure the base unit 14 with a mobile phone. In this case, the computer 15 of the center station 13 is connected to the mobile phone line, and when the center station 13 is called from the mobile phone of the base unit 14, the handset 11 is identified by the ID code and the handset 11 found is searched.
The position information of is reported to the mobile phone of the base unit 14 through the mobile phone line and output as voice. Further, the base unit 1 is provided by a so-called PHS (simple mobile phone) which is a type of mobile phone.
4 can also be configured.

Next, referring to the flowchart of FIG.
The search operation of the system configured as above will be described. As described above, the handset 11 constantly emits radio waves at predetermined time intervals, and each of the base stations 12A to 12C sends predetermined information to the center station 13 each time it receives radio waves from the handset 11. When the center station 13 receives the search start command from the master device 14 (step S1), the center station 13 starts the following search operation. Handset 11 requesting a search for a search start command
ID code is included. Taking the lost child search system as an example, the search start command is transmitted from the parent device 14 by pressing the search start / completion switch of the parent device 14 when the parent loses sight of the child. The base unit 14 is a mobile phone or P
In the case of HS, a call for a search start command is sent from the mobile phone or the like to the center station 13.

When a search start command is received from the base unit 14,
The computer 15 of the center station 13 extracts the ID code of the child device 11 to be searched from the received search start command (step S2), and the center station 13 causes each base station 12 to search.
The information of the child device 11 having the ID code extracted in step S2 is selected from the information of each child device 11 received from A to 12C, and the child device 11 and each base station are selected based on the information. The distances a, b, and c from 12A to 12C are calculated (step S3), and the handset 11 and the base stations 12A to 1 are calculated.
The position of the handset 11 is specified from the three distance data a to c between 2C (step S4). The position information obtained in step S4 is stored in a predetermined area of the memory of the computer 15.

After that, the center station 13 transmits the position information of the child device 11 obtained in step S4 in a predetermined form to the parent device 14 (step S5), and the screen of the computer 15 is displayed as shown in FIG. The locus of the position of the child device 11 at a predetermined time interval is displayed on (step S6).
When the master device 14 is a mobile phone or PHS, the center station 13 informs the mobile phone or the like of the position of the slave device 11 by voice.

After that, it is judged whether or not a search completion command is received from the base unit 14 (step S7). If NO, the process returns to step S3, and if YES, a series of search operations for the handset 11 is ended. . For example, in the case of a lost child search system, the parent sends the search completion command to the center station 13
Lost child (child device 1
When the position 1) is confirmed, the search is started / completed by pressing the search start / completion switch of the base device 14 again. When the parent device 14 is a mobile phone or PHS, a call for a search completion command is sent from the mobile phone or the like to the center station 13.

Therefore, according to this embodiment, the slave unit 1
The base station (antenna) 12 receives the radio wave transmitted from the mobile station 1 and the time of arrival of the radio wave between the mobile station 11 and the base station 12 determines the mobile station 1
1 calculates the distance between the base station 12 and the base station 12, and the search target (child device 1
In order to specify the position of 1), the number of base stations 12 to be installed is three in principle, and the number of base stations to be installed can be greatly reduced as compared with the conventional zone detection method. Moreover,
Since the position is specified from the distance between the handset 11 and the base station 12, the position to be searched can be specified with high accuracy with such a small number of base stations 12.

Further, since the number of base stations 12 to be installed is small, the installation cost is low, which is advantageous in terms of cost. The small number of base stations 12 installed does not cause an aesthetic problem or hinder the movement of people.

Further, according to the present embodiment, since the search start command for the slave 11 is transmitted from the master 14 to the center station 13 and the position information of the slave 11 is transmitted from the center 13 to the master 14, It is possible to request the search of the search target (slave device 11) and confirm the position by the master device 14, and it is not necessary to go to the center station 13 to save time and effort.

Further, according to this embodiment, the center station 1
Search target on the screen of the computer 15 of 3 (slave unit 11)
Since the locus of the position of the
Even if 1) deviates from the search range, it is possible to assume in which direction the deviation has occurred, and search can be performed to some extent.

Further, according to this embodiment, since the slave unit 11 has a unique ID code, a plurality of slave units 11 are provided.
Even if the (radio wave source) exists, the positions of the plurality of slave units 11 can be specified by designating the ID codes.

Furthermore, as the base unit 14, a mobile phone or PHS is used.
If you use, you do not need dedicated equipment for that,
Cost can be reduced. Also, search target (slave unit 11)
Since the position of the center station 13 can be informed by voice as well as being displayed in text, the position information of the center station 13 can be explained in detail through a mobile phone or PHS by a guide arranged in the center station 13. Note that the latter effect can be obtained not only in the case of a mobile phone or PHS but also in the parent device 14 having a speaker.

The present invention is not limited to the lost child search system in the above-mentioned amusement park, zoo, event site, etc., but can be widely applied to a system for specifying a position. For example, identifying a room for a lost child indoors, a vehicle operation management system by identifying the location of a car, tracking a stolen vehicle, searching for a wandering old man (for example, installed near a nursing home),
It is applicable to pet tracking, animal ecology tracking, and other emergency call systems for people and vehicles.

[0035]

As described above, according to the invention described in claim 1, the distance between the slave unit and each base station is calculated from the radio wave arrival time between the slave unit and each base station, and the slave unit Since the position is specified, the position of the child device can be specified with high accuracy with a small number of base stations installed. Having a small number of base stations is not only advantageous in terms of cost, but also effective in avoiding aesthetic problems and spatial restrictions.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since the position information is transmitted from the center station to the base unit, the position of the handset is confirmed by the base unit. It is possible and convenient.

According to the invention of claim 3, in addition to the effect of the invention of claim 2, since the master unit sends a slave unit search start command to the center station, the slave unit search request is transmitted to the parent unit. It can be done by machine and is convenient.

According to the invention of claim 4, in addition to the effect of the invention of any one of claims 1 to 3, the locus of the position of the child device to be searched is displayed on the screen of the center station. Therefore, even if the search target deviates from the search range, it can be assumed in which direction the search target deviates, and the search can be performed to some extent.

According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, since the slave unit has a unique ID code, a plurality of slave units are provided. Even if the machine exists, the positions of the plurality of slaves can be specified by designating the ID codes.

According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 2 to 5, since the base unit is a mobile phone, no dedicated equipment is required. Cost reduction can be achieved. Further, since the position of the child device can be notified by voice as well as by displaying characters, the position information of the center station can be explained in detail by the guide arranged at the center station.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a position detection system of the present invention.

FIG. 2 is a conceptual diagram showing a configuration of a signal transmitted from a child device.

FIG. 3 is an explanatory diagram of a method of position search based on arrival time of radio waves.

FIG. 4 is a diagram showing an example of a screen display of a locus of a search target position.

5 is a flowchart of the search operation of the center station of FIG.

FIG. 6 is an explanatory diagram of a conventional zone detection method.

[Explanation of symbols]

 11 ... Slave unit 12 ... Base station 13 ... Center station 14 ... Master unit 15 ... Computer

Claims (6)

[Claims] 1. A slave unit (11) for transmitting a signal including a current time by radio waves at a predetermined time interval, and a signal received from the slave unit (11) with its reception time and its own identification code added. Between at least three base stations (12) transmitting radio waves, and between the slave unit (11) and each base station (12) based on the information received from each base station (12). A center station (13) for calculating the respective distances and specifying the position of the slave unit (11). 2. The position information of the slave unit (11) specified by the center station (13) corresponds to the corresponding master unit (1).
4. The position detection system according to claim 1, wherein the position detection system is transmitted to 4). 3. The base unit (14) is the center station (1).
The position detection system according to claim 2, wherein a search start command for the corresponding slave unit (11) is output by radio waves to 3). 4. The center station (13) displays a locus of the position of the slave unit (11) on a screen at a predetermined time interval, according to any one of claims 1 to 3. Position detection system. 5. The slave unit (11) has a unique ID code, and the slave unit (11) to be searched is identified by the ID code.
Position detection system described in. 6. The position detection system according to claim 2, wherein the base unit (14) is a mobile phone.