JP2010204028A - Management server, facility system for estimating position, and position estimation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position estimation system for precisely estimating the position of a radio travel node even under environment having many metal objects. <P>SOLUTION: The position estimation system includes: a travel node of which the position is estimated; a plurality of fixed nodes for giving a position reference; and a management server for estimating the position of the travel node according to the distance between each fixed node and travel node. The management server includes: a storage means for storing information on the relationship between the number of reception signals and distance for each fixed node; a number-of-reception-signals acquisition means for allowing the fixed node or travel node to transmit a plurality of signals for measuring distance having different output strength and acquiring the number of reception signals in the other node; a signal conversion means for obtaining distance information between each fixed node and travel node by referring to the storage means, based on the obtained number of reception signals; and a position estimation means for estimating the position of the travel node by applying a plurality of pieces of distance information between each fixed node and the travel node. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a management server, a position estimation facility system, and a distance estimation system, and can be applied, for example, to position estimation in an environment where there are many metal objects that affect radio wave propagation conditions.

  Currently, ironworks and various manufacturing factories are required to centrally manage the current work location (current position) of workers for safety management.

  Therefore, a lot of systems have been developed and studied that give workers a wireless tag and calculate the distance from the fixed wireless node as a reference to the wireless tag using the received radio wave intensity (RSSI) to identify the position. ing. Many of the existing position detection methods (RSSI methods) using received radio field strength estimate the distance between the wireless tag and the wireless node using the property (distance attenuation) that the received radio field strength attenuates in inverse proportion to the distance, The position of the wireless tag is detected based on estimated distances from a plurality of wireless nodes (the principle of three-point surveying) (see Patent Document 1 and Patent Document 2).

JP 2002-250768 A JP 2006-258468 A

  In the conventional position estimation method using distance attenuation of radio waves, distance attenuation becomes abnormally large due to multipath etc. in environments with many metal objects such as ironworks and factories, and the distance between wireless nodes and wireless tags is estimated In most cases, the position cannot be estimated.

  In addition, at ironworks and various manufacturing factories, the position of metal objects varies depending on the progress of work, and the layout is changed according to the work schedule of the day, so that radio wave propagation conditions (radiation distance and distance attenuation) Also changes from moment to moment.

  For example, as shown in FIG. 8, in an environment where there is no metal object (assuming that the metal object is removed), the relationship curve between the distance from the fixed wireless node and the received radio wave intensity is C1. In this case, when there is a metal object in the space and the layout of the metal object is changed, the relationship curve between the distance from the fixed wireless node and the received radio wave intensity is as C2 to C4. From the relationship curves C2 to C4, since the attenuation is not so much, the distance can be specified from the received radio wave intensity is about several meters, and the number m is also changed for each time zone for changing the layout of the metal objects. It can be seen that the distance cannot be specified because the relationship between the received radio wave intensity and the distance changes.

FIG. 9 is an attenuation measurement graph, in which the vertical axis related to the received radio wave intensity and the horizontal axis related to the distance are in exponential notation. The regression line y in FIG. 9 is obtained from a plurality of relationship curves (C2 to C4) as in FIG. 8, and the plurality of plots at each distance show that the received radio wave intensity varies at that distance. (R ² in FIG. 9 is an index representing variation). Although the slope of the regression line y depends on the attenuation rate, the greater the slope of the regression line y, the easier it is to specify the distance from the received radio wave intensity. As shown in FIG. 9, when the inclination is small, it is difficult to specify the distance from the received radio wave intensity, and since there are many plots, it can be seen that many values of the received radio wave intensity are obtained even at the same distance.

  As described above, in an environment where there are many metal objects such as ironworks and factories, the attenuation of the radio wave intensity is large at a small distance, and the variation of the attenuation amount is large, resulting in poor distance estimation accuracy. As a result, the estimated value of the position of the wireless tag obtained from the estimated distance is also low in accuracy.

  Therefore, a management server, a position estimation equipment system, and a position estimation system that can accurately estimate the position of a wireless mobile node even in an environment with many metal objects are desired.

  According to a first aspect of the present invention, the position of the wireless mobile node is determined according to a distance between the wireless mobile node to be estimated, a plurality of wireless fixed nodes that provide a position reference, and each of the wireless fixed nodes and the wireless mobile node. In the position estimation system having a management server for estimation, the management server stores, for each wireless fixed node, monitoring area state storage means for storing relational information between the number of signal receptions and distance, and the wireless fixed node or A first reception number acquisition means for transmitting a plurality of distance measurement signals having different output intensities from the wireless mobile node, and acquiring a signal reception number in the other wireless mobile node or the wireless fixed node; and the acquired signal Based on the number of receptions, referring to the monitoring area state storage means, a signal for obtaining distance information between each wireless fixed node and the wireless mobile node. And Received / distance conversion means, the distance information between each radio fixed node and the wireless mobile nodes plurality applied, and having a position estimation means for estimating a position of the wireless mobile nodes.

  According to a second aspect of the present invention, there is provided a plurality of wireless fixed nodes that provide position references, and a management server that estimates a position of the wireless mobile node according to a distance between each wireless fixed node and a wireless mobile node that is a position estimation target; In the location estimation equipment system, the management server stores, for each wireless fixed node, monitoring area state storage means for storing relationship information between the number of received signals and the distance, and the wireless fixed node or the wireless movement A first reception number acquisition means for transmitting a plurality of distance measurement signals having different output intensities from the node and acquiring the signal reception number in the other wireless mobile node or the wireless fixed node; Based on the monitoring area state storage means, the number of received signals / distance to obtain distance information between each wireless fixed node and the wireless mobile node And converting means, the distance information between each radio fixed node and the wireless mobile nodes plurality applied, and having a position estimation means for estimating a position of the wireless mobile nodes.

  According to a third aspect of the present invention, in the management server that estimates the position of the wireless mobile node according to the distance between the wireless mobile node that is a position estimation target and a plurality of wireless fixed nodes that provide position references, The monitoring area state storage means for storing the relationship information between the number of received signals and the distance, and a plurality of distance measurement signals having different output intensities are transmitted from the wireless fixed node or the wireless mobile node. A first reception number acquisition means for acquiring a signal reception number in the wireless mobile node or the wireless fixed node; and the monitoring area state storage means based on the acquired signal reception number, and each wireless fixed node A signal reception number / distance conversion means for obtaining distance information between the wireless mobile node and the wireless mobile node, and a plurality of distance information between each wireless fixed node and the wireless mobile node. And use, and having a position estimation means for estimating a position of the wireless mobile nodes.

  According to the present invention, since the position of the wireless mobile node is estimated based on the number of received signals transmitted with different output strengths, the wireless mobile node can be used even in an environment where there are many metal objects where the RSSI value varies greatly. The position of the node can be estimated with high accuracy.

It is a block diagram which shows the structure of the position estimation system which concerns on embodiment. It is explanatory drawing of arrangement | positioning and detailed structure of the radio | wireless fixed node of embodiment. It is explanatory drawing which shows the relationship between the radio wave output intensity of the some communication terminal which comprises the radio | wireless fixed node of embodiment, and the distance which can receive the radio wave. It is a block diagram which shows the functional structure seen from the position / state management function surface of the position state management server of embodiment. It is explanatory drawing of the update method of the information showing the propagation state in the monitoring area of embodiment. It is a flowchart which shows operation | movement of the position state management server at the time of grasping | ascertaining the radio | wireless propagation state in the monitoring area of embodiment. It is a flowchart which shows operation | movement of the position state management server at the time of estimating the position of the radio | wireless mobile node of embodiment. It is explanatory drawing (1) of the conventional subject. It is explanatory drawing (2) of the conventional subject.

(A) Main Embodiment Hereinafter, an embodiment of a management server, a position estimation facility system, and a position estimation system according to the present invention will be described with reference to the drawings. The position estimation system of this embodiment is intended for a system that is used in an environment where there are many metal objects that affect radio wave propagation conditions.

(A-1) Configuration of Embodiment FIG. 1 is a block diagram illustrating a configuration of a position estimation system according to an embodiment. The following description will be made assuming that the wireless communication protocol applied by the position estimation system according to the embodiment is ZigBee.

  In FIG. 1, a position estimation system 1 includes a position state management server 2, a display terminal 3, a central warning light 4, a coordinator 5, and a plurality of wireless fixed nodes 6 (6-a to 6-d, 6-1 to 6-10). ) And a wireless mobile node 7. Here, the position state management server 2, the display terminal 3, the central warning light 4, and the coordinator 5 are connected via a wired network (internal LAN) 8. The coordinator 5, the wireless fixed node 6, and the wireless mobile node 7 are arranged in the worker state management area AR and perform wireless communication according to ZigBee. Further, the position state management server 2, the coordinator 5, and the plurality of wireless fixed nodes 6 (6-a to 6-d, 6-1 to 6-10) constitute a position estimation facility system.

  The coordinator 5 has a function of managing the entire ZigBee wireless network (PAN), and is one node in the PAN. In addition, when the worker state management area AR is divided into a plurality of areas so as to partially overlap and a PAN is configured for each divided area, a plurality of coordinators 5 are provided.

  Each wireless fixed node 6 is a reference for position estimation of the wireless mobile node 7. The position state management server 2 has position information of each wireless fixed node 6 and estimates the position of the wireless mobile node 7 from the distance between each wireless fixed node 6 and the wireless mobile node 7. Each wireless fixed node 6 is fixedly attached at a position in the monitoring area AR. For example, as shown in FIG. 2, the wireless fixed nodes 6 are arranged at equal intervals along the x direction and the y direction of the orthogonal coordinate system (xy coordinate system). In FIG. 1, four wireless fixed nodes 6 (6-a to 6-d) are shown, and in FIG. 2, 10 wireless fixed nodes 6 (6-1 to 6-10) are shown. The number does not change.

  Each wireless fixed node 6 includes a plurality (four in FIG. 2) of communication terminals (ZigBee terminals) 10-1 to 10-n. The plurality of communication terminals 10-1 to 10-n are stacked in the normal direction of the above-described orthogonal coordinate system (xy coordinate system), for example, and the communication terminals 10-1 to 10-n are respectively positioned. Under the control of the state management server 2 and the coordinator 5, a beacon (hereinafter referred to as a first field strength transmission request beacon) that means a field strength transmission request directed to the wireless mobile node 7 is periodically transmitted simultaneously. A beacon (hereinafter, referred to as a second field strength transmission request beacon) meaning a field strength transmission request directed to another wireless fixed node 6 is periodically transmitted simultaneously. Here, the plurality of ZigBee terminals 10-1 to 10-n in the same wireless fixed node (for example, 6-1) transmit power (radio wave output intensity) when transmitting the first or second field strength transmission request beacon. ) Are selected to be different (the transmission frequency is also different), and the beacon propagation distance is different.

  FIG. 3 is an explanatory diagram of the relationship between the beacon transmission power (radio wave output intensity) from the communication terminal 10 and the beacon propagation distance.

  For example, the wireless fixed node 6-1 in FIG. 3A has four communication terminals 10-1 to 10-4, and the communication terminal 10-1 has a radio wave output intensity as shown in FIG. The beacon is transmitted at P1, the communication terminal 10-2 transmits the beacon at the radio wave output intensity P2, the communication terminal 10-3 transmits the beacon at the radio wave output intensity P3, and the communication terminal 10-4 is at the radio wave output intensity P4. Suppose you send a beacon. Since the radio wave output intensities P1 to P4 are different, the reachable distances of the transmitted beacons are also different.

  For example, as shown in FIG. 3C, the reachable distance of the beacon transmitted at the radio wave output intensity P1 is 20 m, the reachable distance of the beacon transmitted at the radio wave output intensity P2 is 15 m, and the radio wave output If the reachable distance of the beacon transmitted at the intensity P3 is 10 m and the reachable distance of the beacon transmitted at the radio wave output intensity P4 is 5 m, the beacon receiver (wireless mobile node or If there are other wireless fixed nodes), beacons from four communication terminals 10-1 to 10-4 can be received, and if there is a beacon receiver in the range of 5 to 10m, three communication terminals 10-1 to 10-3 can receive beacons, and when there is a beacon receiver in the range of 10 to 15m, it can receive beacons from two communication terminals 10-1 and 10-2, 20m If there is a receiver of the beacon in a range capable of receiving a beacon from one of the communication terminals 10-1. In other words, if a receiver can receive only two beacons from the four communication terminals 10-1 to 10-4 of the wireless fixed node 6-1, the receiver and the wireless This means that the distance to the fixed node 6-1 is in the range of 15 to 20 m.

  As shown in FIG. 3A, in a situation where the wireless fixed nodes 6-3 and 6-7 have received beacons from the two communication terminals 10-1 and 10-2 of the wireless fixed node 6-1. When the number of beacons that can be received by the wireless fixed nodes 6-3 and 6-7 becomes 1 due to changes in the arrangement of metal objects, the range of the distance of one beacon is the range 15 to that It means that it has moved from 20m to the shorter side, or has expanded its width to the shorter side.

  Each wireless fixed node 6 performs routing for reaching information from the wireless mobile node 7 and information from other wireless fixed nodes (6) to the coordinator 5 (position state management server 2), and the coordinator Information routing from 5 to the wireless mobile node 7 is performed.

  The wireless mobile node 7 is a position estimation target and is carried by or worn by the worker whose state is to be monitored. The wireless mobile node 7 includes, for example, one communication terminal (ZigBee terminal) and is configured in a tag shape (wireless tag). The wireless mobile node 7 transmits the number of received beacons when receiving the first field strength transmission request beacon transmitted from any of the wireless fixed nodes 6. If the received beacon strength (hereinafter referred to as RSSI value as appropriate) is equal to or greater than a predetermined threshold value, it is determined that the signal has been received. In the following description, it is assumed that the transmission destination of the number of received beacons is the wireless fixed node that is the transmission source of the beacon. Note that the wireless mobile node 7 may directly transmit the number of received beacons to the coordinator 5 when other wireless protocols are employed.

  The position state management server 2 has the same configuration as that of a general server in hardware. The position state management server 2 has a function as a ZigBee gateway (ZGW) and a position / state management function. Are executed.

  In terms of the ZigBee gateway function, the position state management server 2 is connected to the coordinator 5 installed in the monitoring area AR, and performs mutual communication as a gateway between the wireless network as the equipment of the monitoring area AR and the internal LAN 8. It is.

In addition, a position detection server function for evaluating the RSSI value from the electric field strength information of the wireless tag of the worker transmitted from the wireless network and performing position estimation by position inference is implemented.

  FIG. 4 is a block diagram showing a functional configuration viewed from the position / state management function side of the position state management server 2.

  The position state management server 2 includes an area state grasping unit 20, a mobile node position estimation unit 21, a mobile node position display unit 22, a warning unit 23, and a database 24 regarding the position / state management function.

  The area state grasping unit 20 periodically grasps (detects) the propagation state of the monitoring area AR, and appropriately updates the stored contents (propagation state information) of the propagation state information database unit 24A of the database 24. The area state grasping unit 20 causes each wireless fixed node 6 to transmit beacons from all communication terminals 10 included in the wireless fixed node 6, captures the number of beacons that can be received by other wireless fixed nodes, and sets other wireless fixed nodes. It is determined whether or not the set of the number of beacons that can be received by the node is the same as the previous time. If it is the same as the previous time, the propagation state information database unit 24A is not updated. Is defined with reference to the positions of other wireless fixed nodes (see FIG. 3), and a center line passing through the center of the width of the band is determined. Then, the average distance from the wireless fixed node 6 that transmitted the beacon to the center line is determined as the distance in the number of received beacons, and such distance information is used as the propagation state information in the propagation state information database. To be registered with the part 24A.

  FIG. 5 is an explanatory diagram of the propagation state information update method described above. “X” in FIG. 5 represents a wireless fixed node that transmits a beacon, and the positions to which the surrounding numbers “4”, “3”, “2”, and “1” are assigned are other wireless fixed nodes. The number represents the number of received beacons at the wireless fixed node. By applying a contour map creation technique, etc., it is possible to define banded areas with the number of received beacons “4”, “3”, “2”, and “1”. A center line is obtained by connecting the centers of the radial widths, and the average of the distances to the radial centers is determined as the distance in the number of received beacons.

  The mobile node position estimation unit 21 periodically estimates the position of the wireless mobile node 7 and updates the stored contents (mobile node position) of the mobile node position database unit 24B of the database 24 as appropriate. The mobile node position estimating unit 21 causes each wireless fixed node 6 to transmit beacons from all communication terminals 10 included in the wireless fixed node 6, captures the number of beacons received by the wireless mobile node 7, and fixes all wireless fixed nodes 6. It is determined whether or not the set of the number of beacons obtained by transmission from the node 6 is the same as the previous time, and if it is the same as the previous time, the mobile node position in the mobile node position database unit 24B is set to the same position and is different from the previous time. In the case, the distance between each wireless fixed node 6 and the wireless mobile node 7 is obtained by referring to the propagation state information database unit 24A, and then the position of the wireless mobile node 7 is determined by applying an existing position estimation algorithm. The position of the wireless mobile node 7 in the mobile node position database unit 24B is estimated and updated.

  The mobile node position display unit 22 extracts the monitoring area layout data 24C from the database 24, extracts the mobile node position of the mobile node position database unit 24B, and displays the monitoring area display layout data including the mobile node position from them. Is given to the display terminal 3 for display.

  The warning unit 23 takes out the warning area data 24D from the database 24, takes out the mobile node position of the mobile node position database unit 24B, and uses the central warning light 4 when the mobile node position is located in the warning area. The notification operation is started.

  The database 24 stores the above-described data of the propagation state information database unit 24A, the data of the mobile node location database unit 24B, the monitoring area layout data 24C, the warning area data 24D, and the like.

  The display terminal 3 displays the position of the non-moving node 7 on the layout of the monitoring area AR under the control of the position state management server 2. The display terminal 3 may be configured integrally with the position state management server 2. Note that the position state management server 2 and the display terminal 3 may be configured to display the topology of the wireless network (the network configuration display of the ZigBee terminal having a PAN configuration) according to the operation of the operator.

  The central warning light 4 performs a warning notification operation of being located in the warning area of the wireless mobile node 7 (the worker who carries it) under the control of the position state management server 2.

(A-2) Operation of Embodiment Next, the operation of the position estimation system according to the embodiment will be described in the order of the grasping operation of the radio propagation state in the monitoring area and the position estimation operation of the wireless mobile node.

  FIG. 6 is a flowchart showing the operation of the position state management server 2 when grasping the wireless propagation state in the monitoring area.

  The position state management server 2 periodically starts the processing shown in FIG. 6 and sets any one of the wireless fixed nodes 6 as a processing target node (step 100). Then, the second electric field strength transmission request beacon is released (broadcast) from all the communication terminals 10 of the wireless fixed node 6 (step 101), and the number of beacons received by all other wireless fixed nodes is captured ( Step 102). Instead of capturing the reception beacon numbers of all other wireless fixed nodes in the monitoring area AR, the reception beacon numbers of all other wireless fixed nodes located within a range determined according to the processing target node are captured. May be.

  After that, it is determined whether or not the set information obtained by collecting the paired information of the number of received beacons and the identification information of the wireless fixed node that outputs the received beacon is the same as the previous set information. (Step 103).

  If the set information is different from the previous set information, the propagation state information for the processing target node is updated as described above (step 104).

  If it is the same as the previous set information, or if it is different from the previous set information and the propagation state information for the processing target node is updated, the position state management server 2 sets a certain wireless fixed node as the processing target node. It is determined whether or not the process has been executed for all the wireless fixed nodes (step 105). If the process has not been executed for all the wireless fixed nodes, the process returns to step 100 described above, and is executed for all the wireless fixed nodes. Then, the series of processes shown in FIG.

  FIG. 7 is a flowchart showing the operation of the position state management server 2 when estimating the position of the wireless mobile node.

  The position state management server 2 periodically starts the process shown in FIG. 7 and sets any one of the wireless fixed nodes 6 as a process target node (step 200). Then, the first field strength transmission request beacon is released (broadcast) from all the communication terminals 10 included in the wireless fixed node 6 (step 201), and the number of beacons received by the wireless mobile node 7 is captured (step 202). . The position state management server 2 determines whether or not the beacon transmission and the reception beacon number fetching process in which a certain wireless fixed node is set as a processing target node have been executed for all the wireless fixed nodes (step 203). If it is not executed for the wireless fixed node, the process returns to step 200 described above.

  On the other hand, if beacon transmission with a certain wireless fixed node set as a processing target node and acquisition processing of the number of received beacons are executed for all wireless fixed nodes, the transmission is obtained from all wireless fixed nodes 6. It is determined whether or not the set of the number of beacons obtained is the same as the previous time (step 204). If it is different from the previous time, the propagation state information for each wireless fixed node 6 is referred to obtain the distance between each wireless fixed node 6 and the wireless mobile node 7, and then the existing position estimation algorithm is applied. Then, the position information is updated by estimating the position of the wireless mobile node 7 (step 205).

  When the set of beacon numbers is the same as the previous time, or when the set of beacon numbers is different from the previous time and the position of the wireless mobile node 7 is reestimated, the series of processes shown in FIG. If there are a plurality of wireless mobile nodes 7, the process shown in FIG. 7 is executed for each wireless mobile node.

(A-3) Effect of Embodiment According to the above embodiment, a plurality of beacons having different output intensities are transmitted from the wireless fixed node, and the number of received beacons of the wireless mobile node is determined between the wireless fixed node and the wireless mobile node. Since rough position information is obtained and the position is estimated, it is possible to eliminate the influence of a metal object or the like from the estimation result rather than applying the RSSI value itself.

  As a result, it is possible to estimate the position of the wireless mobile node even if the monitoring area is an ironworks or factory with many metal objects.

  Here, when a plurality of beacons with different output intensities are transmitted from a certain wireless fixed node, how many beacons can be received at which distance, and the beacons from other wireless fixed nodes to other wireless fixed nodes. Since it is captured from propagation and stored as wireless propagation state information and used for wireless mobile node position estimation, even if the position estimation uses the number of received beacons of the wireless mobile node, a fairly good position An estimation result can be obtained.

  The radio wave propagation situation changes not only due to the arrangement of metal objects but also due to the weather and the movement of people, but the estimation result using the number of received beacons can be improved regardless of the cause of the change.

(B) Other Embodiments In the description of the above-described embodiment, various modified embodiments have been referred to. However, modified embodiments as exemplified below can be cited.

  In the above-described embodiment, ZigBee is applied as a wireless communication protocol. However, the wireless technology and protocol are not limited to this, and Wi-Fi, UWB, or the like can be applied. Any radio technology or the like can be used as long as the received electric field strength changes according to the distance and it can be determined whether or not it is “received” based on the received electric field strength.

  In the above embodiment, the position is estimated by replacing the number of received beacons with the distance so that the existing position estimation algorithm can be applied. However, the position is estimated by replacing the number of received beacons with the range of distance. May be. When grasping the propagation state of the monitoring area AR, a band-shaped area (distance range) with a beacon number of 0, a band-shaped area with a beacon number of 1 are obtained from the wireless fixed node to be processed. At the time of position estimation, based on the number of received beacons, a band-like area that can be seen as seen from a certain radio fixed node is obtained, and the position of the radio mobile node is estimated by overlapping the band-like areas obtained for a plurality of radio fixed nodes You may make it do. In the case of such a method, the boundary between adjacent strip regions may be determined by overlapping.

  In the above embodiment, the wireless fixed node is the beacon transmitting side when estimating the position of the wireless mobile node, but a plurality of communication terminals (for example, ZigBee terminals) are provided in the wireless mobile node. Alternatively, beacons may be transmitted at different output intensities, and information on the distance between each wireless fixed node and the wireless mobile node may be obtained according to the number of beacons that can be received by each wireless fixed node.

  In the above embodiment, a plurality of wireless fixed nodes are arranged at equal intervals. However, as long as the state management server knows, the arrangement is not limited to equal intervals.

  In the above embodiment, a case has been described in which a plurality of communication terminals are provided in a wireless fixed node to enable transmission of beacons having different output strengths. However, one communication terminal capable of varying the output strength is provided in a wireless fixed node. A plurality of beacons having different output intensities may be transmitted in a time-sharing manner by variable output intensity control. However, the time for transmission of all beacons is a short time so that the positions can be regarded as the same.

  In the above embodiment, for all wireless fixed nodes, the same number of transmission beacons and combinations of output strengths at the time of transmission are shown. However, the combination of the number of beacons and output strengths differs depending on the wireless fixed nodes. Also good. For example, a node having a large number of transmission beacons is applied as a wireless fixed node in an area where it is desired to improve the accuracy of position estimation.

  DESCRIPTION OF SYMBOLS 1 ... Position estimation system, 2 ... Position state management server, 3 ... Display terminal, 4 ... Central warning light, 5 ... Coordinator, 6-a-6-d, 6-1-6-10 ... Several radio | wireless fixed nodes, DESCRIPTION OF SYMBOLS 7 ... Wireless mobile node, 8 ... Wired network (internal LAN), 10-1 to 10-4 ... Communication terminal which one wireless fixed node has, 20 ... Area state grasping part, 21 ... Mobile node position estimation part, 22 ... Mobile node position display unit, 23 ... warning unit, 24 ... database.

Claims (6)

A wireless mobile node that is a position estimation target, a plurality of wireless fixed nodes that give position references, and a management server that estimates the position of the wireless mobile node according to the distance between each wireless fixed node and the wireless mobile node In the position estimation system,
The management server is
For each wireless fixed node, monitoring area state storage means for storing the relationship information between the number of received signals and the distance;
First reception number acquisition means for transmitting a plurality of distance measurement signals having different output intensities from the wireless fixed node or the wireless mobile node and acquiring the signal reception number at the other wireless mobile node or the wireless fixed node When,
Based on the acquired signal reception number, referring to the monitoring area state storage means, the signal reception number / distance conversion means for obtaining distance information between each wireless fixed node and the wireless mobile node;
A position estimation system comprising position estimation means for estimating a position of the wireless mobile node by applying a plurality of distance information between each wireless fixed node and the wireless mobile node. The management server is
A second reception number acquisition means for transmitting a plurality of state grasping signals having different output intensities from a certain wireless fixed node, and acquiring a signal reception number in the other wireless fixed node;
Based on the signal reception number acquired by the second reception number acquisition means, the signal reception number and distance stored in the monitoring area state storage means for the wireless fixed node that has transmitted the state grasping signal. The position estimation system according to claim 1, further comprising monitoring area state updating means for updating the relationship information. A position estimation facility system comprising: a plurality of wireless fixed nodes that provide a position reference; and a management server that estimates the position of the wireless mobile node according to the distance between each of the wireless fixed nodes and a wireless mobile node to be estimated In
The management server is
For each wireless fixed node, monitoring area state storage means for storing the relationship information between the number of received signals and the distance;
First reception number acquisition means for transmitting a plurality of distance measurement signals having different output intensities from the wireless fixed node or the wireless mobile node and acquiring the signal reception number at the other wireless mobile node or the wireless fixed node When,
Based on the acquired signal reception number, referring to the monitoring area state storage means, the signal reception number / distance conversion means for obtaining distance information between each wireless fixed node and the wireless mobile node;
A position estimation system comprising position estimation means for estimating a position of the wireless mobile node by applying a plurality of distance information between each wireless fixed node and the wireless mobile node. The management server is
A second reception number acquisition means for transmitting a plurality of state grasping signals having different output intensities from a certain wireless fixed node, and acquiring a signal reception number in the other wireless fixed node;
Based on the signal reception number acquired by the second reception number acquisition means, the signal reception number and distance stored in the monitoring area state storage means for the wireless fixed node that has transmitted the state grasping signal. The position estimation facility system according to claim 3, further comprising monitoring area state updating means for updating the relationship information. In the management server that estimates the position of the wireless mobile node according to the distance between the wireless mobile node that is the position estimation target and the plurality of wireless fixed nodes that give the position reference
For each wireless fixed node, monitoring area state storage means for storing the relationship information between the number of received signals and the distance;
First reception number acquisition means for transmitting a plurality of distance measurement signals having different output intensities from the wireless fixed node or the wireless mobile node and acquiring the signal reception number at the other wireless mobile node or the wireless fixed node When,
Based on the acquired signal reception number, referring to the monitoring area state storage means, the signal reception number / distance conversion means for obtaining distance information between each wireless fixed node and the wireless mobile node;
A management server comprising: position estimation means for estimating a position of the wireless mobile node by applying a plurality of distance information between each of the wireless fixed nodes and the wireless mobile node. A second reception number acquisition means for transmitting a plurality of state grasping signals having different output intensities from a certain wireless fixed node, and acquiring a signal reception number in the other wireless fixed node;
Based on the signal reception number acquired by the second reception number acquisition means, the signal reception number and distance stored in the monitoring area state storage means for the wireless fixed node that has transmitted the state grasping signal. The management server according to claim 5, further comprising monitoring area state updating means for updating the relationship information.

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