JP2011185646A - Management server, facility system for position estimation, and position estimating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position estimating system capable of estimating the position of a wireless mobile node, even in an environment where many metallic substances exist. <P>SOLUTION: This position estimating system includes the wireless mobile node, a plurality of wireless fixed nodes, and a management server. Each wireless fixed node intermittently adjusts the intensity of a radio wave output of a radio signal to be transmitted from itself, so that the arrivable range of the radio signal from itself becomes constant. The wireless mobile node transmits information on the group of wireless fixed nodes of all of transmission sources which have received radio waves within the latest predetermined period, including identification information to the management server. With respect to each combination among the plurality of wireless fixed nodes, the management server previously stores information associating each combination with a position zone where the wireless mobile node is estimated to be situated in that combination, and when the group information is given from the wireless mobile node, a search is performed using this group information as a key, and a position zone where the wireless mobile node is situated is estimated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a management server, a position estimation facility system, and a position 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, Patent Document 2, and Non-Patent Document 1).

JP 2002-250768 A JP 2006-258468 A

Masayuki Ono et al., “Position detection using radio”, Oki Technical Review Vol. 72 NO. 4 pp. 24-27 October 2005

  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. 9, 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. 10 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. 10 is obtained from a plurality of relationship curves (C2 to C4) as in FIG. 9, and the plurality of plots at each distance show that the received radio wave intensity varies at that distance. (R ² in FIG. 10 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. 10, when the inclination is small, it is difficult to specify the distance from the received radio wave intensity, and it can be seen that many received radio wave intensity values are taken even at the same distance because there are many plots.

  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 in 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.

  In worker management at ironworks and various manufacturing factories, as shown in Fig. 11, management at the level of ZN1 to ZN6 such as zone (which worker is located between pillars) in each factory building is realized. Want to do. However, in an environment where there are many metal objects that affect radio wave propagation as described above, and their arrangements change from moment to moment, the poor accuracy of distance estimation results in inaccurate position estimation even at the zone level. There was a fear.

  Therefore, a management server, a position estimation facility system, and a position estimation system that can estimate a zone where a wireless mobile node is located even in an environment where there are many metal objects are desired.

  According to a first aspect of the present invention, there is provided a position estimation system comprising: a wireless mobile node that is a position estimation target; a plurality of wireless fixed nodes that provide position references; and a management server that estimates a position of the wireless mobile node. Each wireless fixed node is provided with radio wave output intensity adjusting means for intermittently adjusting the radio wave output intensity of the radio signal from itself so that the range in which the radio signal from itself reaches is constant, (2) the radio The mobile node includes set information transmitting means for transmitting to the management server set information including identification information of all radio fixed nodes that have received radio signals within a recent predetermined period, and (3) The management server stores (3-1) information in which a combination of a plurality of the above-described wireless fixed nodes is associated with a position zone that can be estimated that the wireless mobile node is located at the time of the combination. (3-2) When the set information is given from the wireless mobile node, the set information / position zone storage means is searched using the set information as a key. And position estimation means for estimating a position zone where the wireless mobile node is located.

  According to a second aspect of the present invention, there is provided a location estimation facility system including a plurality of wireless fixed nodes that provide a position reference and a management server that estimates a position of a wireless mobile node. (2) The management server includes (2-1) radio wave output intensity adjusting means for intermittently adjusting the radio wave output intensity of the radio signal from itself so that the range in which the radio signal reaches is constant. For each combination of a plurality of the above-mentioned wireless fixed nodes, a set information / position zone storage means for storing information in which a position zone that can be estimated that the wireless mobile node is located at the time of the combination is stored (2- 2) The set information transmitted by the wireless mobile node includes identification information of all the wireless fixed nodes of the transmission sources that the wireless mobile node has received wireless signals within the most recent predetermined period. Position estimation means for searching for the set information / position zone storage means by using the set information as a key and estimating the position zone where the wireless mobile node is located, when information is given from the radio mobile node; It is provided with.

  According to a third aspect of the present invention, in the management server in the position estimation system, the position estimation target wireless mobile node, a plurality of wireless fixed nodes that provide a position reference, and a management server that estimates the position of the wireless mobile node are provided. (1) For each combination of a plurality of the above-mentioned wireless fixed nodes, a set information / position zone storage unit storing information in which a position zone that can be estimated that the wireless mobile node is located at the time of the combination is stored; (2) The radio mobile node was able to receive the radio signal emitted by each radio fixed node with the radio wave output intensity adjusted so that the range in which the radio signal from itself arrives was constant within the predetermined period When the set information including the identification information of all the wireless fixed nodes of the transmission source is given from the wireless mobile node, the set information is used as a key, Searches the information / position zone storage means, characterized in that the wireless mobile nodes and a position estimation means for estimating a location zone located.

  According to the present invention, it is possible to estimate a zone where a wireless mobile node is located even in an environment with many metal objects.

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 which shows the relationship between the arrival distance from each radio | wireless fixed node of embodiment, and a position zone. It is a flowchart which shows operation | movement of the radio wave output intensity automatic adjustment mode in the radio | wireless fixed node of embodiment. It is a flowchart which shows the production | generation operation | movement of the group information corresponding | compatible position zone information in the position state management server of embodiment. It is a flowchart which shows the position estimation operation | movement of the radio | wireless mobile node in the position state management server of embodiment. It is explanatory drawing (1) of the conventional subject. It is explanatory drawing (2) of the conventional subject. It is explanatory drawing (3) 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. As described later, the position state management server 2 has position information of each wireless fixed node 6, and the position (zone to which the position belongs) of the position of the wireless mobile node 7 from the range of 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 y direction of the orthogonal coordinate system (xy coordinate system) (for example, attached to columns at equal intervals). . 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 communication terminal (ZigBee terminal). Hereinafter, the communication terminal is also referred to as a wireless fixed node. The wireless fixed node 6 periodically transmits a beacon (hereinafter referred to as a first beacon) directed to the wireless mobile node 7 under the control of the position state management server 2 and the coordinator 5, or other wireless fixed nodes A beacon (hereinafter referred to as a second beacon) for receiving a response to 6 or a beacon (hereinafter referred to as a beacon for returning a reception response to the transmission source wireless fixed node when the second beacon is received) Or a third beacon).

  Each wireless fixed node 6 can vary the radio wave output intensity, and periodically reviews the radio wave output intensity from itself.

  FIG. 3 is an explanatory diagram of the relationship between the beacon transmission power (radio wave output intensity) from the wireless fixed node 6 and the beacon propagation distance. The vertical axis in FIG. 3B represents not only the radio wave output intensity but also the received radio wave intensity (RSSI value described later).

  Even in an environment where there are many metal objects that affect radio wave propagation, and their arrangement is changed from moment to moment, when the wireless fixed node 6 transmits a beacon with a strong radio wave output intensity, the radio wave output intensity is weaker. The distance that the beacon reaches is longer than when the beacon is transmitted. If there is a radio wave output intensity P1 at which the beacon from the wireless fixed node 6-1 in FIG. 3A cannot reach the closest wireless fixed nodes 6-2 and 6-5, the wireless fixed node 6-1 Of the radio fixed node 6-2 and 6-5, but if there is a radio wave output intensity P2 that cannot reach the radio fixed node farther than that, the beacon from the radio fixed node 6-1 There is also a radio wave output intensity P3 that reaches the fixed nodes 6-2, 6-3, 6-5, and 6-7, but cannot reach a radio fixed node farther than that.

  Even if the environment changes, a beacon arrives at a certain (closer) other wireless fixed node from a certain wireless fixed node, but the beacon does not reach other wireless fixed nodes farther than that. The strength can be selected (reviewed). In this embodiment, as will be described later, the radio wave output intensity from the wireless fixed nodes is periodically reviewed so that the range (and hence the distance range) of other wireless fixed nodes to which the beacons from each wireless fixed node reach is constant. I have to. Each wireless fixed node 6 holds information (reach range fixed node information) of other wireless fixed nodes to which the second beacon from itself should reach. The reachable range fixed node information is, for example, set directly by the operator for the wireless fixed node 6, but the operator inputs it to the position state management server 2, and the position state management server 2 stores it in each wireless fixed node 6. It may be transferred to.

  Each wireless fixed node 6 performs routing for causing information from the wireless mobile node 7 and information from other wireless fixed nodes 6 to reach the coordinator 5 (position state management server 2), and the coordinator 5 Routing of information from the mobile node 7 to the wireless mobile node 7.

  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 set information of the identification information of all the wireless fixed nodes 6 of the transmission source that have received the first beacon within the predetermined time immediately before the predetermined time. Here, it is determined that the received first beacon is “received” when the strength of the first beacon (hereinafter, appropriately referred to as an RSSI value) is equal to or greater than a predetermined threshold. The group information described above may be transmitted to the position state management server 2 via an arbitrary wireless fixed node 6, or transmitted to the position state management server 2 via the coordinator 5. May be.

  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. (Including the position detection server function).

  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 estimating the position (position zone) of the wireless mobile node 7 based on the set information from the wireless mobile node 7 of the worker transmitted from the wireless network 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 location state management server 2 has a zone information setting unit 20, a mobile node location estimation unit 21, a mobile node location display unit 22, a warning unit 23, and a database 24 regarding the location / state management function.

  The zone information setting unit 20 generates zone information for estimating the zone in which the wireless mobile node 7 is located from the information on the reachable range fixed node given from each wireless fixed node 6 and stores (sets) the zone information in the database 24. It is something to be made. The zone information is largely a position zone corresponding to the reach range fixed node information itself that the second beacon from each radio fixed node 6 needs to reach and the set information transmitted by the radio mobile node 7. The former reachable range fixed node information is stored in the reachable range fixed node information database unit 24A, and the latter set information corresponding position zone is stored in the position zone database unit 24B. The reachable range fixed node information may be input to the position state management server 2 by the operator.

  FIG. 5 is an explanatory diagram showing the relationship between the reachable distance from each wireless fixed node and the position zone, in other words, an explanatory diagram of the significance of the zone information.

  In FIG. 5, the assigned area (reach range) of the radio fixed node 6-1 includes the radio fixed nodes 6-2 and 6-5 and does not include the radio fixed node farther than these, and thereby the radio fixed node is fixed. The node 6-1 periodically reviews the radio wave output intensity so that the second beacon from itself reaches the wireless fixed nodes 6-2 and 6-5 and does not reach the wireless fixed nodes farther than these. To do. In addition, the area in charge of the wireless fixed node 6-5 includes the wireless fixed nodes 6-1 and 6-7, and does not include the wireless fixed nodes farther than these. The radio wave output intensity is periodically reviewed so that the second beacon from itself reaches the wireless fixed nodes 6-1 and 6-7 and does not reach the wireless fixed nodes farther than these. Further, the area in charge of the wireless fixed node 6-2 includes the wireless fixed nodes 6-1 and 6-3, and does not include a wireless fixed node farther than that. The radio wave output intensity is periodically reviewed so that the second beacon from itself reaches the wireless fixed nodes 6-1 and 6-3 and does not reach the wireless fixed nodes farther than these. Furthermore, the area in charge of the wireless fixed node 6-4 includes the wireless fixed nodes 6-3 and 6-6, and does not include a wireless fixed node farther than that. The radio wave output intensity is periodically reviewed so that the second beacon from itself reaches the wireless fixed nodes 6-3 and 6-6 and does not reach the wireless fixed nodes farther than these.

  In such a situation, if the identification information of the wireless fixed nodes 6-1, 6-2, and 6-5 is included in the set information from the wireless mobile node 7, the first zone AR1 in FIG. If the wireless mobile node 7 can be estimated to be located and the identification information of the wireless fixed nodes 6-2 and 6-6 is included in the set information from the wireless mobile node 7, the second zone in FIG. It can be estimated that the wireless mobile node 7 is located in AR2. In the latter case, the wireless mobile node 7 seems to be located at a position where the first beacon from the wireless fixed node 6-3 can reach, but for some reason, the wireless mobile node 7 Even if the beacon 1 does not arrive, the wireless mobile node 7 is located in the second zone AR2 due to the set information including the identification information of the wireless fixed nodes 6-2 and 6-6. Can be estimated.

  The above-described set information corresponding position zone is information of a position zone determined according to given set information. The zone information setting unit 20 generates group information corresponding position zone information based on the reach range fixed node information given from each wireless fixed node 6 and the position of each wireless fixed node 6 in the monitored area. Note that the operator may input information about the set information corresponding position zone and store it.

  The mobile node position estimation unit 21 of the position state management server 2 accesses the set information corresponding position zone database unit 24B of the database 24 using the group information periodically given from the radio mobile node 7 as a key, and the radio mobile node 7 The position (position zone) is estimated. The mobile node position estimation unit 21 additionally stores the estimated position in the database 24.

  The mobile node position display unit 22 takes out the monitoring area layout data 24C from the database 24, takes out the estimated mobile node position zone, and forms monitoring area display layout data including the mobile node position from them. Is provided 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 estimated position zone of the mobile node, and uses the central warning light 4 when the position zone of the mobile node is located in the warning area. The notification operation is started.

  The database 24 stores various data as described above.

  The display terminal 3 displays the wireless mobile node 7 in the estimated position zone 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 that the wireless mobile node 7 (the worker carrying it) is located in the warning area 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 includes the automatic adjustment operation of the radio wave output intensity in the wireless fixed node, the generation operation of the position information corresponding to the group information, the position of the wireless mobile node The estimation operation will be described in this order.

  FIG. 6 is a flowchart showing the operation of the radio wave output intensity automatic adjustment mode in the wireless fixed node 6. This operation is periodically performed by all the wireless fixed nodes. Hereinafter, the operation will be described assuming that the wireless fixed node 6-1 is executing. The operation will be described assuming that the fixed range nodes of the wireless fixed node 6-1 are the wireless fixed nodes 6-2 and 6-5.

  The wireless fixed node 6-1 periodically starts the processing shown in FIG. 6, first, sets the set value of the radio wave output intensity to the initial value (step 100), and releases (broadcasts) the second beacon. (Step 101). The initial value of the radio wave output intensity may be a predetermined fixed value (for example, the minimum value or the maximum value of the adjustable range), and the immediately preceding set value of the radio wave output intensity is used as the initial value. Anyway. In addition, the other wireless fixed node that has received the second beacon returns the third beacon as described above.

  The wireless fixed node 6-1 returns the third beacon from any other wireless fixed node after elapse of sufficient time that the returned third beacon can be reached after the second beacon is released. It is determined whether or not it has been made (step 102).

  When the third beacon is not returned from at least one of the wireless fixed nodes 6-2 and 6-5 that are reachable range fixed nodes, the wireless fixed node 6-1 has insufficient previous radio wave output intensity. As a result, the set value of the radio wave output intensity is increased by one unit (step 103), and the process returns to the second beacon emission process of step 101 described above.

  When the third beacon is returned from not only the wireless fixed nodes 6-2 and 6-5 that are reachable range fixed nodes but also other wireless fixed nodes, the wireless fixed node 6- 6 In step 1, since the previous radio wave output intensity is excessive, the set value of the radio wave output intensity is decreased by one unit (step 104), and the process returns to the second beacon emission process in step 101 described above.

  On the other hand, when the third beacon is returned only from the wireless fixed nodes 6-2 and 6-5 that are reachable range fixed nodes, the wireless fixed node 6-1 As appropriate, the series of processing shown in FIG. 6 is terminated.

  Radio fixed nodes other than the radio fixed node 6-1 also regularly execute the operation of the automatic adjustment mode as shown in FIG.

  By the operation in the automatic adjustment mode, any radio fixed node can always achieve the radio wave reach allocated to the radio fixed node. That is, each wireless fixed node 6 periodically emits (broadcasts) the first beacon in the normal mode, but the radio wave output intensity when the first beacon is emitted is set in the immediately preceding automatic adjustment mode. It is possible to achieve the radio wave reach allocated to the wireless fixed node.

  Next, the generation operation of the position information corresponding to the group information in the position state management server 2 will be described. FIG. 7 is a flowchart showing this operation. The generation operation of the group information corresponding position zone information is executed when the position estimation system 1 of the embodiment is started up or when the radio fixed node 6 is increased or decreased.

  When the position state management server 2 starts the process shown in FIG. 7, first, information on other wireless fixed nodes to which the second beacon from each of the wireless fixed nodes 6 should reach (reach range fixed node). Information) and store it in the database unit 24A (step 200).

  Thereafter, one unprocessed unit area in the unit area into which the monitoring target area is subdivided is set as a processing target (step 201), all wireless fixed nodes that reach the unit area by the first beacon are recognized, and the unit The correspondence information between the area and the wireless fixed node pair is buffered in the pair information corresponding position zone database unit 24B (step 202). For example, if the unit area has a size of 50 cm × 50 cm and the center of the unit area is within an arc of a distance determined by the reachable range fixed node information centered on a certain radio fixed node, the first from the radio fixed node Beacon is reached.

  Thereafter, for all unit areas, it is checked whether the recognition and storage processing (step 202) of all the wireless fixed nodes to which the first beacon arrives have been completed (step 203). Return to step 201.

  When the processing of step 202 is completed for all unit areas, the location state management server 2 links the unit areas with the same combination of wireless fixed nodes to which the first beacon arrives into zones, Information on the information corresponding position zone is generated and stored in the database unit 24B (step 204), and the series of processes shown in FIG. 7 is terminated.

  Next, the position estimation operation of the wireless mobile node in the position state management server 2 will be described. FIG. 8 is a flowchart showing this operation.

  As described above, each wireless fixed node 6 periodically releases (broadcasts) the first beacon. The wireless mobile node 7 always waits for the first beacon, and when receiving the first beacon, stores the identification information of the wireless fixed node 6 that is the transmission source of the first beacon. The wireless mobile node 7 periodically transmits the stored set information of the wireless fixed node 6 (identification information) to the position state management server 2. The interval of periodic transmission is the same as the interval at which the wireless fixed node 6 emits the first beacon, for example. In addition, after the previous transmission, the stored set of identification information of the wireless fixed node 6 is transmitted at the present periodic transmission timing.

  When the processing shown in FIG. 8 is started, the position state management server 2 waits for any wireless mobile node 7 to receive the set information of the wireless fixed node 6 (step 300). When the set information of the wireless fixed node 6 is given from any of the wireless mobile nodes 7, the position state management server 2 accesses the information of the set information corresponding position zone in the database unit 24B using the set information as a key, and A position zone corresponding to the group information is specified (step 301).

  Thereafter, the location state management server 2 determines whether or not the identified location zone is the same as the previous location zone (step 302), and if so, returns to step 300 and returns to the wireless fixed node 6 Wait for group information to be given.

  On the other hand, when the specified location zone is different from the previous location zone, the location state management server 2 makes the location zone of the target wireless mobile node 7 the specified location zone. The display image by the display terminal 3 is updated (step 303). Further, the position state management server 2 determines whether or not the specified position zone is a warning area (step 304). If it is not a warning area, the process returns to step 300 and the set information of the wireless fixed node 6 is given. Await.

  If the identified position zone is a warning area, the position state management server 2 uses the central warning light 4 to warn that the wireless mobile node 7 (the worker carrying it) is located within the warning area. The notification operation is executed (step 305), and then the process returns to step 300 to wait for the set information of the wireless fixed node 6 to be given.

(A-3) Effect of Embodiment According to the above-described embodiment, the radio wave output intensity is periodically automatically adjusted from the wireless fixed node, and the distance reached by the first beacon from each wireless fixed node is always constant. In this way, the position (position zone) of the wireless mobile node is estimated based on the set information of the wireless fixed node of the transmission source from which the wireless mobile node has received the first beacon. Rather, the influence of metal objects and the like can be eliminated from the estimation result.

  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.

  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 result of estimating the position of the wireless mobile node 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 the signal is “received” based on the received electric field strength.

  In the above embodiment, the radio output intensity of the wireless fixed node is adjusted so that it can be received by another predetermined wireless fixed node. However, any other type can be used as long as the reach can be substantially constant. The wireless fixed node may be adjusted so that it cannot be received. For example, the radio wave output that gradually increases the radio wave output intensity from the minimum value and emits the first beacon by a value that is smaller by one unit from the radio wave output intensity value that other wireless fixed nodes can receive. You may make it set to the value of intensity | strength.

  Furthermore, although the wireless fixed node 6 autonomously adjusts the radio wave output intensity is shown in the above embodiment, it may be adjusted in response to an instruction from the position state management server 2. Depending on the applied wireless technology, there is a possibility that a plurality of wireless fixed nodes performing adjustment may compete if autonomous adjustment is applied. However, when the location state management server 2 gives an instruction, Conflicts can be eliminated.

  The adjustment radio wave output intensity candidate value may also be given from the position state management server 2 each time.

  In the above embodiment, the interval at which the radio fixed node adjusts the radio wave output intensity is regular, but may be irregular. For example, each wireless fixed node is set with information on the source wireless fixed node located at a position where the first beacon does not reach itself, and the first beacon from the wireless fixed node is received. In this case, the received wireless fixed node reports to the position state management server 2 to activate adjustment of the transmission source wireless fixed node, or the received wireless fixed node directly notifies the transmission source wireless fixed node. Then, the adjustment may be activated (in this notification, the radio wave output intensity is increased more than usual).

  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.

  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), 20 ... Zone information setting part, 21 ... Mobile node position estimation part, 22 ... Mobile node position display part, 23 ... Warning part, 24 ... Database.

Claims (3)

In a position estimation system having a wireless mobile node for position estimation, a plurality of wireless fixed nodes that give a position reference, and a management server that estimates the position of the wireless mobile node,
Each of the wireless fixed nodes includes a radio wave output intensity adjusting unit that intermittently adjusts the radio wave output intensity of the radio signal from itself so that a range in which the radio signal from itself reaches is constant,
The wireless mobile node includes set information transmitting means for transmitting, to the management server, set information including identification information of all transmission-fixed wireless fixed nodes that have received a radio signal within a recent predetermined period,
The management server
For each combination of a plurality of wireless fixed nodes, set information / location zone storage means storing information that associates a position zone that can be estimated that the wireless mobile node is located at the time of the combination;
Position estimation means for searching the set information / position zone storage means using the set information as a key and estimating the position zone where the wireless mobile node is located when the set information is given from the wireless mobile node A position estimation system characterized by comprising: In a location estimation facility system having a plurality of wireless fixed nodes that give a location reference and a management server that estimates the location of a wireless mobile node,
Each of the wireless fixed nodes includes a radio wave output intensity adjusting unit that intermittently adjusts the radio wave output intensity of the radio signal from itself so that a range in which the radio signal from itself reaches is constant,
The management server
For each combination of a plurality of wireless fixed nodes, set information / location zone storage means storing information that associates a position zone that can be estimated that the wireless mobile node is located at the time of the combination;
The set information transmitted by the radio mobile node, including the identification information of all the radio fixed nodes of the transmission source that the radio mobile node has received radio signals within the most recent predetermined period, A position estimation means for searching for the set information / position zone storage means using the set information as a key and estimating the position zone where the wireless mobile node is located, when given by the mobile node; A feature location estimation system. In the management server in the position estimation system, comprising: a wireless mobile node for position estimation, a plurality of wireless fixed nodes that give a position reference, and a management server that estimates the position of the wireless mobile node;
For each combination of a plurality of wireless fixed nodes, set information / location zone storage means storing information that associates a position zone that can be estimated that the wireless mobile node is located at the time of the combination;
All the wireless signals that the wireless mobile node has received within the most recent predetermined period can receive the wireless signals emitted by the wireless fixed nodes with the radio wave output intensity adjusted so that the range in which the wireless signal from itself reaches is constant. When set information including identification information of a wireless fixed node as a transmission source is given from the wireless mobile node, the set information / position zone storage means is searched using the set information as a key, and the wireless movement is performed. And a position estimation means for estimating a position zone where the node is located.

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