JP2008249670A - Positioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the precision of positioning a mobile station using the measured distances among a plurality of mobile stations, when it is possible to measure the distances among the plurality of mobile stations. <P>SOLUTION: A positioning system includes: a presence probability calculation section for calculating presence probability to the positions of mobile stations, based on positioning results by a positioning section; a second distance measuring section for measuring the distance among the plurality of mobile stations while having distance measurement precision higher than that of a first measurement section; a mobile station position extraction section for extracting the combination of the positions of the plurality of mobile stations, based on the distance among the plurality of mobile stations measured by the second distance measuring section; a mobile station position selection section for calculating a probability evaluation value corresponding to the combination of the positions of the plurality of mobile stations, based on the presence probability, and selecting the combination of the positions of the plurality of mobile stations having the highest probability evaluation value; a mobile station position correction section for correcting the positions of the plurality of mobile stations that are the positioning results by the positioning section so that they become the combinations of the positions of the mobile stations selected by the mobile station position selection section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a system for detecting the positions of a plurality of mobile stations that transmit radio waves and move within a predetermined movable region, and in particular, consider the mutual distance between the plurality of mobile stations detected by means other than radio waves. The present invention relates to a system that performs highly accurate position detection.

  A system for detecting and tracking the position of a person or an object by using wireless communication has been proposed. For example, a system called a Global Positioning System (GPS). For example, as shown in Non-Patent Document 1, the GPS receives radio waves transmitted from a plurality of satellites by a single movable receiver, and based on the arrival time difference between the received radio waves, A system for detecting the position of a receiver.

  In this GPS, the position is detected when the receiver receives radio waves from a satellite at a known position, but conversely, radio waves transmitted from one movable transmitter can be detected by a plurality of known radio waves. It is also possible to detect the position of the transmitter based on the radio waves received by the plurality of receivers received by the receiver fixed at the position. For example, in Patent Document 1, a radio signal between a plurality of reference stations that are wireless devices whose positions are known and a detection target station that is a wireless device whose position is unknown is transmitted to one of the plurality of reference stations or the detection target stations. Measuring the physical quantity related to the distance to measure the absolute distance or relative distance between the reference station and the detection target station, and the distance measurement results that are the measured distances and the positions of the reference stations. Based on the above, a method for calculating the position of the detection target station is disclosed.

  By the way, when a plurality of mobile stations can communicate with each other and at the same time the distance between the plurality of mobile stations can be measured, a technique for calculating the positions of the plurality of mobile stations, that is, positioning is disclosed in Patent Literature. 2 is disclosed.

Introduction to GPS Technology Takeyasu Sakai Tokyo Denki University Press (February 2003) JP 2006-090913 A JP 2002-152798 A

  However, the technique disclosed in Patent Document 2 is difficult for some mobile stations to communicate with a base station among mobile stations that can communicate with each other at the same time and can measure a mutual distance. This is used when positioning cannot be performed based on the communication of the mobile station, and the positioning result of the mobile station that can perform positioning based on the communication with the base station, the mobile station that can perform the positioning, and the positioning cannot be performed. Based on the relative positional relationship with the mobile station, the mobile station that cannot perform the positioning is positioned. Therefore, the measurement of the distance between mobile stations is not used to improve the accuracy of positioning of the mobile stations.

  The present invention has been made against the background of the above circumstances, and its purpose is to measure the distance between a plurality of mobile stations when the distance between the plurality of mobile stations can be measured. The purpose of this is to improve the accuracy of positioning of a mobile station.

  In order to solve this problem, the inventor of the present invention has conducted various experiments and examinations. As a result, the measurement of the distance between the plurality of mobile stations requires a means other than communication, for example, reciprocation of transmitted ultrasonic waves. If time is used, short-range ranging provides more accurate results than ranging using radio waves, and communication between the mobile station and the base station is based on the accurate distance between the plurality of mobile stations. We found that more accurate positioning is possible by correcting the results of positioning based on this.

  The present invention has been made on the basis of such knowledge, and the gist of the invention according to claim 1 is that (a1) a plurality of transmitters that can move in a predetermined movable region and transmit radio waves. Mobile station, (a2) a receiving unit that receives radio waves transmitted by the plurality of mobile stations, and a first distance measuring unit that measures distances from the plurality of mobile stations based on the received radio waves A plurality of base stations fixed at known positions, and (a3) positioning units that respectively position the plurality of mobile stations based on distance data measured by the plurality of base stations. In a positioning system having a positioning server, (b) a presence probability calculating unit that calculates positioning results by the positioning unit as existence probabilities for the positions of the plurality of mobile stations in the movable area; 2) a second distance measuring unit that has a higher distance measurement accuracy than the first distance measuring unit and measures the distance between the plurality of mobile stations; and (d) measured by the second distance measuring unit. A mobile station position extraction unit that extracts a combination of positions of the plurality of mobile stations in the movable area based on distances between the plurality of mobile stations; and (e) presence calculated by the existence probability calculation unit Based on the probability, the probability evaluation value corresponding to the combination of the positions of the plurality of mobile stations extracted by the mobile station position extraction unit is calculated, and the combination of the positions of the plurality of mobile stations having the highest probability evaluation value And (f) correcting the plurality of mobile station positions, which are positioning results by the positioning section, to be a combination of the positions of the mobile stations selected by the mobile station position selecting section. Mobile station position supplement And parts, characterized in that it has.

  According to this configuration, in the positioning system, the existence probability calculation unit calculates the existence probabilities for the positions of the plurality of mobile stations in the movable area based on the positioning result by the positioning unit, respectively. The distance between the plurality of mobile stations is measured with higher distance measurement accuracy than the first distance measurement section by the second distance measurement section, and is measured by the second distance measurement section by the mobile station position extraction section. A combination of positions of the plurality of mobile stations in the movable region is extracted based on the distance between the plurality of mobile stations, and the existence probability calculated by the existence probability calculation unit by the mobile station position selection unit On the basis of the probability evaluation value corresponding to the combination of the positions of the plurality of mobile stations extracted by the mobile station position extraction unit, A combination of positions of the plurality of mobile stations having a high value is selected, and the plurality of mobile station positions, which are positioning results by the positioning section, are selected by the mobile station position selecting section by the mobile station position correcting section. Since the correction is made so as to be a combination of the positions of the mobile stations, highly accurate positioning is executed.

  Preferably, the mobile station has the second distance measuring unit, and the result of the distance measurement by the second distance measuring unit is determined by the mobile station position extracting unit via radio waves transmitted by the transmitting unit. Is transmitted to. In this way, since the mobile station has the second distance measuring unit, the distance between the mobile station and another mobile station is measured, and the result of the distance measurement is a transmitter unit of the mobile station. Can be transmitted to the mobile station extraction unit by solving the radio wave.

  Preferably, the positioning server includes the existence probability calculation unit, the mobile station position extraction unit, a mobile station position selection unit, and the mobile station position correction unit. In this way, calculations necessary for the position of the mobile station can be aggregated and executed by the positioning server.

  Preferably, the second distance measuring unit performs distance measurement using sound waves, preferably ultrasonic waves. In this way, since the distance between a specific mobile station and another mobile station is measured using sound waves whose speed is slower than that of radio waves, more accurate distance measurement is possible than using radio waves. .

  Preferably, the second distance measuring unit includes an image recognition camera, and performs distance measurement based on an image captured by the image recognition camera. In this way, since the distance between the plurality of mobile stations is measured based on the image captured by the image recognition camera, the mobile station does not need to include a sensor or the like.

  Preferably, the second ranging unit includes a specific mobile station that is one mobile station that is to accurately perform position correction among the plurality of mobile stations, and the specific movement is performed by the positioning unit. It is characterized in that it measures the distance from another mobile station that is supposed to be present at the position closest to the station. In this way, the second distance measuring unit measures the distance between the specific mobile station and another mobile station that is supposed to be closest to the specific mobile station. Distance error is reduced.

  Preferably, the mobile station position selection unit, when there is a combination of positions of a plurality of the mobile stations where the calculated probability evaluation value is within a predetermined range set in advance, Based on the movement history of the mobile station before execution of the selection unit, a combination of the positions of the mobile stations is selected. In this way, even if there is a combination of a plurality of mobile station positions whose probability evaluation values are within a predetermined range, the combination of the mobile station positions based on the movement history of the mobile station Therefore, a combination of mobile station positions in accordance with the actual mobile station position can be selected.

  Preferably, the movement history of the mobile station is information relating to the position of the mobile station before the execution of the mobile station position selection unit. In this way, since information on the position of the mobile station before the execution of the mobile station position selection unit is used as the movement history of the mobile station, the combination of the positions of the mobile stations in accordance with the actual position of the mobile station Can be selected.

  Further preferably, the movement history of the mobile station is information relating to movement of the mobile station before execution of the mobile station position selection unit. In this way, since information on the movement of the mobile station before the execution of the mobile station position selection unit is used as the movement history of the mobile station, the position of the mobile station according to the actual position of the mobile station is used. A combination can be selected.

  Preferably, the mobile station position selection unit calculates the existence probability when there are a plurality of combinations of positions of the mobile stations in which the calculated probability evaluation value is within a predetermined range set in advance. A combination of positions of the mobile stations having a high probability of existence of the specific mobile station calculated by a unit is selected. In this way, even when there is a combination of positions of a plurality of the mobile stations whose probability evaluation values are within a predetermined range, the existence probability of the specific mobile station calculated by the existence probability calculation unit Since the combination of the positions of the mobile stations having a high value is selected, the position of the specific mobile station is corrected more accurately.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an example of the configuration of the positioning system 8 of the present invention. In FIG. 1, a movable region 50 formed of a square having a side 30 (m) is provided as a movable region 50 provided in an arbitrary shape on a plane. The movable area 50 includes four base stations, a first base station 12A, a second base station 12B, and a third base station, as the base station 12 having a function of performing wireless communication with the mobile station 10 described later. 12C and a fourth base station 12D are provided. As will be described later, when the position of the mobile station is obtained from the propagation arrival time of the radio wave as described later, at least three base stations are required for calculating the position of the mobile station 10 on the plane. Accordingly, at any point in the movable area, the base station is arranged so that at least the mobile station can communicate with the three base stations. Further, the position of the mobile station can be calculated more accurately as the number of base stations increases. In FIG. 1, one first base station 12 </ b> A to four fourth base stations 12 </ b> D are arranged at four corners of a square movable area 50, respectively, and this requirement is satisfied. A plurality of mobile stations 10 are arranged in the movable area 50 and can move in the movable area 50. In FIG. 1, two mobile stations 10A and 10B are arranged as an example. The number of mobile stations is not particularly limited as long as it is two or more. In addition, a positioning server 14 is provided that is communicable with the base station 12 by, for example, a wired cable 52, and the mobile station 10 transmits the mobile station 10 based on radio waves transmitted by the mobile station 10 and received by the base station 12. The position of the base station 10 in the possible area is calculated. In the present specification, the mobile stations 10A and 10B are indicated as mobile stations 10 when not distinguished from each other, and the base stations 12A through 12D are indicated as base stations 12 when not distinguished from each other.

  At this time, the x-axis and the y-axis are defined for the movable area 50 as shown in FIG. 2 for convenience, and the coordinates of the points on the movable area 50 are defined based on these axes. That is, the first base station 12A is on the coordinates (0, 0), the second base station 12B is on the coordinates (0, 30), the third base station 12C is on the coordinates (30, 30), and the fourth base station The stations 12D are respectively arranged on the coordinates (30, 0).

  FIG. 3 is a functional block diagram showing an outline of the configuration of the mobile station 10. The antenna unit 20 is used for transmitting and receiving radio waves, and the balanced / unbalanced converting unit 22 is a balun, and converts the unbalanced line of the transmission / reception switching unit 24 into a balanced line so as to match the antenna unit 20. The controller 401 is a control circuit including a known microcomputer and its peripheral circuits, and controls the operation of the mobile station 10 by controlling a transmission / reception switching unit 24 described later.

  The transmission / reception switching unit 24 switches between the transmission state and the reception state of the mobile station 10 in FIG. That is, when the transmission / reception switching unit 24 switches the mobile station 10 to the transmission state, the mobile station 10 functions as a transmitter, and when it switches to the reception state, the mobile station 10 functions as a receiver. In addition, when the mobile station 10 is caused to function as a transmitter by the transmission / reception switching unit 24, the transmission amplifier unit 26 amplifies a signal wave generated by the radio unit 28 described later.

  When the mobile station 10 is caused to function as a transmitter, the radio unit 28 converts a signal generated by the control unit 32 (to be described later) into a format for performing wireless communication so that the mobile station 10 functions as a receiver. In the case where the signal is received, the received wave received by the antenna unit 20 is converted into a signal to be processed by the control unit 32, which is implemented by, for example, an IC. Specifically, the radio unit 28 includes a PLL circuit (phase lock loop) circuit, a VCO (Voltage Controlled Oscillator) circuit, a digital modulation demodulator 30 and the like that generate a carrier wave of a predetermined frequency according to a command from the controller 401. The digital modulation demodulator 30 digitally modulates the signal generated by the control unit 32 and demodulates the received signal received, and outputs the generated digital data to the control unit 32 so that the mobile station 10 and the base station Wireless communication with 12 is performed by digital communication.

  The control unit 32 includes a spectrum spreading unit 34, a despreading processing unit 341, a baseband signal generation / restoration unit 36, a spreading code generation unit 38, and the like. For example, a gate having a function of controlling these blocks and generating a spreading code It is implemented by an array or a microcomputer. Among these, when the mobile station 10 is caused to function as a transmitter, the baseband signal generation / restoration unit 36 encodes information to be transmitted and generates a baseband signal. Further, when the mobile station 10 or the base station 12 is caused to function as a receiver, the transmitted information is extracted from the baseband signal decoded by the despreading processing unit 341 described later.

  The spread code generator 38 generates a spread code for performing spread spectrum by the spread spectrum unit 34 described later. As this spreading code, the autocorrelation function has a high peak, i.e., when the phase difference is zero, the autocorrelation has a large value, whereas when the phase difference is not zero, the autocorrelation is sufficiently small, and A code string that satisfies the condition that the correlation between codes is sufficiently small in all phase differences, that is, the cross-correlation is small is used. Specifically, for example, an M-sequence code or a Gold sequence code that is also used in GPS is used. This Gold sequence code is also called a pseudo-noise code (PN signal).

  When the mobile station 10 is caused to function as a transmitter, the spread spectrum unit 34 uses the baseband signal generated by the baseband signal generation / restoration unit 36 using the spread code generated by the spread code generation unit 38. Spread spectrum to generate a signal for transmission. Specifically, for example, a direct spread method using an exclusive OR of the baseband signal and the spreading code as a result is used. Further, when the mobile station 10 is caused to function as a receiver, the despreading processing unit 341 performs spectrum despreading on the received wave demodulated by the digital modulation / demodulation unit 30 using the spreading code, and performs baseband Take out the signal. In the case of this reception, the same spreading code as in the case of transmission is used. Using such spread spectrum, when communication between a specific mobile station and a base station is performed using a specific spread code, other mobile stations and base stations at the same time and at the same frequency Even when the communication with is performed using another spreading code, the mutual communication is not affected.

  These antenna unit 20, balanced / unbalanced switching unit 22, transmission / reception switching unit 24, transmission amplifier 26, radio unit 28, control unit 32 and the like blocks for transmitting radio waves correspond to the transmitting unit and the receiving unit.

  The second distance measuring section 70 corresponding to the second distance measuring section includes at least one of the sound wave transmitter and the sound wave sensor 72 or the image recognition camera 76, and the own mobile station 10 and other movements other than itself. The distance to the station 10 is measured, that is, the distance is measured. For example, when the second distance measuring unit 70 uses the sound wave transmitter and the sound wave sensor 72, the sound wave transmitted by the sound wave transmitter of its own mobile station 10 is reflected by the other mobile station 10 and its own Based on the time until the mobile station 10 detects the sound wave sensor and the propagation speed of the sound wave in the air, the distance between the mobile station 10 of the mobile station 10 and another mobile station 10 other than the mobile station 10 is calculated. Specifically, the time required for the sound wave transmitted by the sound wave transmitter of its own mobile station 10 to be reflected by the other mobile station 10 and detected by the sound wave sensor of its own mobile station 10 By multiplying the half by the propagation speed of the sound wave, the distance between the mobile station 10 of its own and another mobile station 10 other than itself is calculated. At this time, in order to reflect sound waves suitably, the mobile station 10 may have a sound wave reflection member (not shown) in addition to the sound wave transmitter and the sound wave sensor 72. As the sound wave transmitter and the sound wave sensor 72, an ultrasonic wave transmitter and an ultrasonic sensor are particularly used in consideration of the property that accurate distance measurement can be performed.

  When the second distance measuring unit 70 uses the image recognition camera 76, the size of the other mobile station 10 in the image captured by the image recognition camera 76 and the other movement stored in advance are stored. Based on the information about the size of the station 10 and the information about the magnification and the curvature of the lens, the distance between the mobile station 10 and another mobile station 10 other than the mobile station 10 is measured.

  FIG. 4 is an example of shapes that the mobile station 10 can take when the second distance measuring unit 70 uses the image recognition camera 76. In this way, if the mobile station 10 has a substantially spherical shape, a substantially similar image can be obtained regardless of the direction taken by the image recognition camera 76. 10 can be easily recognized, and at the same time, the distance from the mobile station 10 captured using the image can be easily calculated. Here, the term “substantially spherical” means that there is no problem of having irregularities and protrusions that do not affect the distance calculation method described later.

  FIG. 5 and FIG. 6 are diagrams for explaining how the second distance measuring unit 70 calculates a distance from another mobile station 10 using the image recognition camera 76. In FIG. 5, a certain mobile station 10A is about to calculate the distance from another mobile station 10B. At this time, the mobile station is substantially spherical as described above, and its radius is r. FIG. 6 shows an example of an image captured by the image recognition camera 76 in the mobile station 10A. In the image having the total number of pixels p1 in the vertical direction, the mobile station 10B has the maximum number of pixels in the vertical direction. Thus, it is a circular image of p2. Also, assuming that the actual length in the height direction corresponding to the total number of pixels p1 in the vertical direction is h, the ratio between the height in the height direction h and the diameter 2r of the mobile station 10B is: Is equal to the ratio of the total number of pixels p1 in the vertical direction and the maximum value p2 of the number of vertical pixels in the image corresponding to the mobile station 10B. That is, h: 2r = p1: p2. On the other hand, the distance L between the image recognition camera 76 and the target object is determined by the length h in the height direction and the specification of the lens, and this specification is given in advance. Accordingly, the mobile station 10A moves from the total number of pixels p1 in the vertical direction on the image, the maximum number of pixels p2 in the vertical direction of the image corresponding to the mobile station 10B, the radius r of the mobile station 10B, and the lens specifications. The distance L with the station 10B can be calculated. In this description, the vertical direction is taken as an example, but the present invention can be similarly applied to the horizontal direction of an image.

  The power supply unit 40 supplies necessary power to the transmission amplifier 26, the radio unit 28, the control unit 32, the clock 41, and the like described above. The clock 41 supplies an operation command of the control unit and time information referred to when a radio wave is transmitted or received, and is a reference clock, for example. .

  FIG. 7 is a functional block diagram showing an outline of the configuration of the base station 12. For functional blocks having the same reference numerals such as the antenna unit 20, balance-unbalance converter 22, transmission / reception switching unit 24, transmission amplifier 26, radio unit 28, control unit 32, clock 41, power supply unit 40, etc. Since it is common to the station 10, the description thereof is omitted. That is, the base station 12 also has both functions as a transmitter and a receiver, like the mobile station 10 described above.

The first ranging unit 42 corresponding to the first ranging unit is a time difference between the time when the radio wave is transmitted by the mobile station 10 and the time when the base station 12 receives the radio wave, that is, the time required for the arrival of the radio wave. Based on the above, the distance between the mobile station 10 and the base station 12 is measured. The first distance measuring unit 42 includes, for example, a matched filter, and specifically includes, for example, a replica code generation unit 44, a delay circuit 46, a correlation calculation unit 50, and the like. In the replica code generation unit 44, the mobile station 10 generates a replica code that is the same code as the spread code generated by the spread code generation unit 38 and used in the spectrum spread unit 34. Then, in the delay circuit 46 constituted by a known shift register, a signal wave in the radio wave transmitted by the mobile station 10 and received by the base station 12 is input and delayed at a plurality of predetermined intervals. It is done. In the correlation calculation unit 50, the correlation coefficient between the reception delayed by the delay circuit 46 and the replica code is calculated. As a result, the reception time when the calculated correlation coefficient becomes maximum is set as the arrival time of the radio wave from the mobile station 10. Since the transmission time by the mobile station 10 is obtained by restoring the baseband signal by the baseband signal creation / restoration unit 36, the time difference between the arrival time and the transmission time of the radio wave is calculated, and the radio wave velocity c (2.997) is calculated. The distance from the mobile station 10 is calculated by multiplying × 10 ⁸ (m / s)).

  In addition, the base station 12 is provided with a wired communication unit 43 for performing communication with a positioning server 14 to be described later. For example, a first communication is established between the base station 12 and the positioning server 14 connected by a wired cable 52 such as a LAN cable. Ranging data that is the distance from the mobile station 10 measured by the ranging unit 42, data including the baseband signal decoded from the received wave by the baseband signal creation / restoration unit 36, information on the operation of the base station 12, etc. Can be transmitted and received. This wired communication unit 43 corresponds to a base station information transmission unit.

  Returning to FIG. 1, the positioning server 14 includes, for example, a so-called computer having a CPU, a RAM, a ROM, an input / output interface, and the like, and a program stored in the ROM in advance using the temporary storage function of the RAM. By performing signal processing according to the above, calculation of the position of the mobile station 10, that is, positioning is executed.

  FIG. 8 is a functional block diagram illustrating the control operation of the positioning server 14. The positioning server 14 includes a positioning unit 56, a mobile station selection unit 104, an existence probability calculation unit 102, a mobile station position extraction unit 106, a mobile station position selection unit 108, a mobile station position correction unit 110, a positioning result storage unit 112, and a positioning result. An output unit 60 and the like are included.

First, the positioning unit 56 calculates the position of the mobile station 10 in the movable area 50 based on the distance between the base station and the mobile station calculated by the plurality of base stations 12, for example. Specifically, for example, when the movable region 50 is a plane as shown in FIG. 1, the coordinates of the first base station 12A are (x ₁ , y ₁ ) and the coordinates of the second base station 12B are (x ₂ , y ₂ ), the coordinates of the third base station 12 C are (x ₃ , y ₃ ), the distance between the first base station 12 A and the mobile station 10 measured by the first base station 12 A is r ₁ , 2 The distance between the second base station 12B measured by the base station 12B and the mobile station 10 is r ₂ , the distance between the second base station 12C measured by the third base station 12C and the mobile station 10 is r, and the mobile station If the coordinates are (x, y) and the error s is based on the time difference between the clocks 41 of the mobile station 10 and the base station 12, respectively, as shown in FIG.
(X−x ₁ ) ² + (y−y ₁ ) ² = (r ₁ + s) ²
(X−x ₂ ) ² + (y−y ₂ ) ² = (r ₂ + s) ² (1)
(X−x ₃ ) ² + (y−y ₃ ) ² = (r ₃ + s) ²
There is a relationship represented by At this time, the clock of the clock 41 included in each of the first base station 12A, the second base station 12B, and the third base station 12C is synchronized by, for example, a method described later, and the error s is common to each base station. is there. At this time, since there are three variables x, y, and s and the above three equations, the values of x, y, and s are calculated by solving these three expressions by, for example, the Newton-Raphson method. It is possible. Note that, as described above, the distance between the first base station 12A to the third base station 12C and the mobile station 10 obtained by measurement by the distance measuring unit 42 included in each of the first base station 12A to the third base station 12C. r ₁ , r ₂ , and r ₃ are so-called pseudoranges in which the error s based on the time lag of the clock 41 of each of the mobile station 10 and the base station 12 is not considered. Instead of the distances r ₁ , r ₂ , and r ₃ , accurate distances in which the error s based on the clock deviation is corrected may be used.

  Thus, when the movable region 50 is a plane, there are three variables. Therefore, if there are at least three expressions, the values of these variables are calculated, and this is the minimum of three base stations 12. Means that the position of the mobile station 10 can be calculated. On the other hand, when there are four or more base stations, it is possible to calculate the position of the mobile station 10 with higher accuracy by using a least square method that minimizes an error in the calculation.

  FIG. 10 is a time chart showing an example of a procedure for synchronizing the clocks 41 included in the four base stations 12. In this figure, the state of communication between each base station and the positioning server is shown by arrows connecting the first base station 12A to the fourth base station 12D and the positioning server 14 in the horizontal direction represented by vertical lines. Yes. The direction of the arrow indicates the direction of communication, and the device to which the arrow is pointing is the receiving side. An arrow indicated by a broken line indicates wireless communication. Also, the time axis is taken downward in the figure, and the time progresses as it goes down.

  First, at time t1, the positioning server 14 issues a command for searching for an empty channel in wireless communication to any one base station 12 (the first base station 12A in the figure). In response to this, the first base station 12A performs a channel scan, and transmits information on the found empty channel to the positioning server 14 at time t2. Subsequently, at time t3, the positioning server 14 issues an instruction to wirelessly transmit time information to any one base station 12 (first base station 12A in the figure). Further, from time t4 to time t6, time information is sequentially transmitted from the positioning server 14 to each of the base stations other than the arbitrary one base station (second base station 12B to fourth base station 12D in this figure). A command to receive is issued. Subsequently, at time t7, time information, that is, time t information of the clock 41 of the first base station 12A is transmitted from the first base station 12A by radio and received by the second base station 12B to the fourth base station 12D by radio. Is done. Furthermore, the time information received by each of the second base station 12B to the fourth base station 12D from time t8 to time t10, that is, the time of the first base station and the second base at the time of transmission transmitted by the first base station 12A. Information including the time received by each of the stations 12B to 4D is sequentially transmitted to the positioning server by the wired communication unit 43.

  Here, since the position of each base station 12 is known, the propagation time required for the radio wave transmitted from the first base station 12A to reach each of the second base station 12B to the fourth base station 12D is It is calculated in advance. Therefore, for each of the second base station 12B to the fourth base station 12D, a value obtained by subtracting the propagation time from the time of the reception time and the time of the transmission from the first base station 12A is the second base station 12B to the fourth base station 12B. There is a time lag between the clock 41 of the base station 12D and the clock 41 of the first base station 12A. By correcting the clocks 41 of the second base station 12B to the fourth base station 12D from time t11 to time t13 so that the time lag calculated in this way is eliminated, the clocks of the base stations 12 are synchronized. .

  FIG. 11 is a time chart for calculating the distance r between each base station 12 and the mobile station 10 used by the positioning unit 56. In this figure, the state of communication between each base station and the positioning server by arrows connecting the first base station 12A to the fourth base station 12D and the positioning server 14 and the mobile station 10 in the horizontal direction represented by vertical lines. It is shown. The direction of the arrow indicates the direction of communication, and the device to which the arrow is pointing is the receiving side. An arrow indicated by a broken line indicates wireless communication. Also, the time axis is taken downward in the figure, and the time progresses as it goes down.

  First, at time t1, the positioning server 14 issues a command for searching for an empty channel in wireless communication to any one base station 12 (the first base station 12A in the figure). In response to this, the first base station 12A performs a channel scan, and transmits information on the found empty channel to the positioning server 14 at time t2. Subsequently, at time t3, an instruction to wirelessly transmit an instruction to wirelessly transmit time information to the mobile station 10 from the positioning server 14 to any one base station 12 (first base station 12A in the figure). Is done. In response to this, at time t4, the first base station 12A transmits to the mobile station 10 a command for wirelessly transmitting time information. Further, from time t5 to time t8, the positioning server 14 issues a command to sequentially receive time information by radio to each of all base stations (first base station 12A to fourth base station 12D in the figure). . Subsequently, at time t9, time information from the mobile station 10, that is, time information of the clock 41 of the mobile station 10, is transmitted by radio and is received by the first base station 12A to the fourth base station 12D by radio. Based on this received signal, the distance measuring unit 42 of each base station 12 calculates the distance between each base station 12 and the mobile station 10, and from time t10 to time t13, the first base station 12A to fourth base station 12D. The calculated distance r between each of the base stations 12 and the mobile station 10 is transmitted to the positioning server 14 by the wired communication unit 43.

  The distances r1 to r4 between the first base station 12A to the fourth base station 12D and the mobile station 10 thus obtained and the position information of each base station are substituted into the equation (1). ) Is solved by the Newton-Raphson method or the least square method, the position coordinates (x, y) of the mobile station 10 are calculated.

  Returning to FIG. 8, the mobile station selection unit 104 selects the mobile station 10 for which the positioning result is to be corrected with high accuracy based on an instruction from the operator, for example. In this way, the mobile station 10 selected by the mobile station selection unit 104 is set as a specific mobile station. In the present embodiment, the first mobile station 10A is selected as the specific mobile station. Further, based on the result of the positioning performed by the positioning unit 56, for example, another mobile station 10B that is considered to be closest to the specific mobile station 10A is selected and set as a target for distance measurement by the second distance measuring unit. .

このようにして算出された発生確率を縦軸に、横軸に測位結果の真値μからのずれをとって描いた図が図１２である。このように、測位結果には誤差が発生するので、移動局１０の測位が行われ移動局の存在する位置のｘ座標がμであるとされた場合であっても、実際には測位結果μを中心とした範囲において図１２において表された確率で移動局１０が存在し、必ずしも測位結果μの位置に存在するわけではないのである。 The existence probability calculation unit 102 calculates the positioning error based on the result of the positioning performed by the positioning unit 56 provided in the base station 12, and the mobile station 10 in the coordinates based on the calculated positioning error. And the existence probability corresponding to the existence position are calculated. Here, as the positioning error, for example, a standard deviation of positioning results executed a predetermined number of times or more is used. The predetermined number of times is a number sufficient to calculate at least the standard deviation. FIG. 12 shows an example in which attention is paid only to the x-axis direction. First, the existence probability calculation unit 102 calculates the standard deviation σ based on the positioning result already performed. For example, assume that σ = 3. Subsequently, using the standard deviation σ of the positioning result, a deviation x from the true value μ of the positioning result and an occurrence probability f corresponding to the deviation x are calculated. Specifically, it is expressed as the following equation (1).

FIG. 12 is a diagram in which the occurrence probability calculated in this way is plotted on the vertical axis and the horizontal axis indicates the deviation from the true value μ of the positioning result. As described above, since an error occurs in the positioning result, even if the positioning of the mobile station 10 is performed and the x coordinate of the position where the mobile station exists is μ, the positioning result μ actually The mobile station 10 exists with the probability represented in FIG. 12 in the range centered on, and does not necessarily exist at the position of the positioning result μ.

  Based on the distance L between the specific mobile station 10A and the other mobile station 10B measured by the second ranging unit 70, the mobile station position extraction unit 106 and the specific mobile station 10A A combination of positions that can be taken by the mobile station 10B is extracted. Specifically, based on the distance measurement data L obtained by measuring the distance from the specific mobile station 10 </ b> A to the other mobile station 10 </ b> B using the second distance measuring unit 70, the movable area 50. A combination of positions that the specific mobile station 10A and other mobile stations 10B can take is extracted. For the sake of simplicity, when the case where the specific mobile station 10A and the other mobile station 10B move within the movable region 50 defined by a straight line is taken as an example, the coordinate xa of the specific mobile station 10A and the coordinates of the other mobile station 10B All combinations in which the difference from xb is the distance L are extracted. For example, when L is 11, combinations of positions that the specific mobile station 10A and other mobile stations 10B can take are (xa, xb) = (0, 11), (1, 12), ( 2, 13),...

The mobile station position selection unit 108 determines the result of positioning by the positioning unit 56 and the existence probability with respect to the combinations of positions that can be taken by the specific mobile station 10A and the other mobile station 10B extracted by the mobile station position extraction unit 106. Based on the existence probability for each base station 10 calculated by the calculation unit 102, the probability evaluation value of the extracted combination is calculated, and the probability evaluation value of the calculated combination is set to the highest probability evaluation value. Select the corresponding combination. Specifically, first, for each base station constituting the combination, its existence probability is calculated based on the relationship shown in FIG. 12, for example, based on the deviation from the positioning result of each base station. Then, the number obtained by multiplying the calculated existence probability of the specific mobile station 10A constituting the combination and the existence probability of each of the other mobile stations 10B is set as the probability evaluation value of the combination. That is, for the combination (xa, xb), if the positioning result is (μa, μb), the existence probability of each mobile station in that case is (fa, fb), and the probability evaluation value of the combination is f. Since fa is a function of a deviation (μa−xa) from the positioning result of the specific mobile station 10A, it is written as fa (μa−xa), and fb is similarly a deviation fb from the positioning result of the other mobile station 10B. It is expressed by (μb−xb). At this time, the probability evaluation value of the combination is f = fa (μa−xa) × fb (μb−xb)
It becomes. In this way, the probability evaluation value f is calculated for a plurality of the combinations, and the combination (xamax, xbmax) corresponding to the probability evaluation value having the maximum value fmax is selected.

  FIG. 13 shows this state with an example of the movable region 50 defined by the straight line. In the figure, the horizontal axis (x-axis) represents the movable region 50, and the vertical axis represents the existence probability. As a result of positioning by the positioning unit 56, it is assumed that the specific mobile station 10A is calculated to exist at the point A1 of x = 8, and the other mobile stations 10B are calculated to exist at the point B1 of x = 18. The relationship between the deviation from the positioning result calculated by the existence probability calculating unit 102 and the existence probability is applied to these positioning results. In the figure, the curves described as the existence probability fa of 10A and the existence probability fb of 10B are those.

  On the other hand, it is assumed that the distance from the specific mobile station 10A measured by the second positioning unit 70 to the other mobile station 10B is L. At this time, the combination of the specific mobile station 10A and the other mobile station 10B extracted by the mobile station position extraction unit 106 is a combination whose interval is L, such as A21 and B21, A22 and B22, or A23 and B23 in the figure. An infinite number are extracted. Then, for each combination of the specific mobile station 10A and the other mobile station 10B extracted in this way, the existence probability fa corresponding to the position of the specific mobile station 10A and the position of the other mobile station 10B are corresponded. The existence probability fb is calculated, and the calculated fa and fb are multiplied to calculate the probability evaluation value f of the combination.

  The probability evaluation values f corresponding to the combinations calculated in this way are compared, and the combination having the highest value fmax is selected. For example, in FIG. 13, when the specific mobile station 10A is A21 and the other mobile station 10B is B21, and the probability evaluation value f of the combination is maximum, the specific mobile station 10A is A21 and the other mobile station 10B. Is selected from B21.

  When the probability evaluation value f corresponding to each combination calculated by the mobile station selection unit 108 is compared, the probability corresponding to another combination within a predetermined range with the highest value fmax as an upper limit. When the evaluation value f exists, the mobile station selection unit 108 selects a mobile station in consideration of the existence probability of the specific mobile station 10A. This will be specifically described with reference to the example of FIG. For example, the probability evaluation value f21 corresponding to the combination in which the specific mobile station 10A is A21 and the other mobile station 10B is B21, and the combination in which the specific mobile station 10A is A22 and the other mobile station 10B is B22 When the probability evaluation value f22 belongs to a predetermined range Δf, that is, | f11−f22 | <Δf, the existence probability of the specific mobile station 10A is considered.

  Specifically, the specific mobile station 10A is A21 and the other mobile station 10B is B21, and the specific mobile station 10A is A22 and the other mobile station 10B is B22. Reference is made to the existence probability of the station 10A. Then, a combination of the specific mobile stations 10A having a higher existence probability is selected as a combination of positions of the mobile stations 10. In the example of FIG. 13, since the existence probability of the specific mobile station 10A is higher than the existence probability in A22, the specific mobile station 10A is A21 and the other mobile stations 10B are B21. A combination is selected. In this way, the position of the mobile station can be calculated in consideration of the position accuracy of the specific mobile station 10A, which is the mobile station whose position is to be calculated with high accuracy.

  Returning to FIG. 8, the mobile station position correction unit 110 is configured such that the position of each mobile station 10 measured by the positioning unit 56 is the position of the mobile station that constitutes the combination of the mobile stations selected by the mobile station position selection unit 108. It is corrected so that Specifically, in the example of FIG. 13, the positioning results determined by the positioning unit 56 are selected by the mobile station position selection unit 108 as A1 for the specific mobile station 10A and B1 for the other mobile station 10B. Since the combination of the specific mobile station 10A and the other mobile station 10B is A21 and B21, since A1 and A21 match, the position of the specific mobile station 10A is not corrected, while the position of the other mobile station 10B is B1. To B21. The result of this correction is the positioning result of each of the specific mobile station 10A and the other mobile station 10B.

  The positioning result output unit 60 outputs the positioning result, that is, the calculated position information of the mobile station 10 to, for example, a monitor device (not shown) or transmits it to another program. In addition, the positioning result storage unit 112 stores the positioning result of the mobile station 10 corrected by the mobile station position correction unit 110 for the past predetermined number of times, and uses it as movement history information of the mobile station 10.

  FIG. 14 is a flowchart for explaining the outline of the control operation of the positioning system of the present invention. First, in step S1 (hereinafter, “step” is omitted), the base station 12 asks the mobile station 10 for the response of the mobile station in order to check whether the mobile station 10 is operating effectively. A call is made. In response to this, a response to that effect is sent from the mobile station 10 that is operating normally.

  In the subsequent S2, it is determined whether or not the response from the mobile station 10 in S1 is from two or more mobile stations. If there is a response from two or more mobile stations, the determination in this step is affirmed and S3 and subsequent steps are executed. On the other hand, when there is a response from one mobile station or when there is no response from any mobile station, S1 is executed again, assuming that there are not a plurality of mobile stations 10 that are the premise of this flowchart. Wait for multiple mobile stations to work effectively.

  In S3 corresponding to the positioning unit 56, position detection is performed on the plurality of mobile stations 10 responding in S1. In S4 corresponding to the subsequent mobile station selection unit 104, one mobile station for which the operator wants to perform accurate positioning is selected as the specific mobile station 10A among the plurality of mobile stations 10 measured in S3. . Further, one base station to be subject to distance measurement is selected as another base station 10B by the second distance measuring unit 70 of the specific mobile station 10A. The other base station 10B automatically determines a base station other than the specific mobile station 10A when two base stations responded in S1. When the number of base stations that responded in S1 is 3 or more, for example, the mobile station whose position detected in S3 is closest to the specific mobile station 10A is selected.

  In S5 corresponding to the second ranging unit 70 of the specific mobile station 10A, the distance from the specific mobile station 10A to another mobile station 10B is measured. As described above, the second distance measuring unit 70 is provided with at least the sound wave sensor 72 or the image recognition camera 76, and distance measurement using this is performed.

  In S6, the result of the distance measurement performed in S5 is transmitted from the specific mobile station 10A to the base station 12 by wireless communication, and further transmitted to the positioning server connected to the base station 12 by the cable 52.

  In S7 corresponding to the existence probability calculating unit 102, the existence probability corresponding to the deviation between the positioning result in S3 of each base station 10 and the actual existence position is calculated. This existence probability is calculated based on the normal distribution based on the standard deviation as the positioning error calculated based on the positioning results of the positioning system 8 so far.

  Subsequent S8 and S9 correspond to the mobile station position extraction unit 106. Among these, in S8, based on the position of the mobile station 10 calculated in S3 and the existence probability calculated in S7, for example, as shown in 13, there is a distribution diagram representing the existence probability with respect to the position of each mobile station. Created.

  In S9, for example, based on the distribution map created in S8 and the distance from the specific mobile station 10A measured in S5 to the other mobile station 10B, the location of the specific mobile station 10A and other movements A combination with the station 10B is extracted.

  S 10 to S 12 correspond to the mobile station position selection unit 108. First, in S10, the probability evaluation values of the combinations are calculated for the combinations extracted in S9 based on the existence probabilities of the specific mobile stations 10A and the existence probabilities of the other mobile stations 10B constituting each combination. At the same time, the combination having the highest calculated probability evaluation value is selected as a combination of mobile station positions.

  In the subsequent S11, it is determined whether or not the probability evaluation values corresponding to other combinations are included in the predetermined range Δf whose upper limit is the highest probability evaluation value in S10. If this determination is affirmative, the combination selected in S10 is selected as it is, and S13 is executed. On the other hand, if this determination is negative, S12 is executed in consideration of the other combinations.

  In S12, the combination of the highest probability evaluation value selected in S10 based on the existence probability of the specific mobile station 10A and the other combination in which the probability evaluation value is included in the range Δf in S11. Which one is selected as a combination of mobile station positions is determined. Specifically, as described above, a combination including the specific mobile station 10A having a higher existence probability of the specific mobile station 10A is selected.

  In S13 corresponding to the mobile station position correction unit 110, the specific mobile station 10A calculated in S3 and the other mobile stations 10B so as to be the combination selected as the combination of the mobile station positions in S10 or S12. Is corrected.

  According to the above-described embodiment, in the positioning system 8, the presence probability calculation unit 102 corresponding to the presence probability calculation unit causes the positioning result obtained by the positioning unit 56 corresponding to the positioning unit to be a plurality of mobile stations 10 in the movable region 50. Are calculated as existence probabilities for the positions of the first and second distance measuring sections 70 corresponding to the second distance measuring section, and the first distance measuring section in which the distance between the plurality of mobile stations 10 corresponds to the first distance measuring section. Based on the distances between the plurality of mobile stations 10 measured by the second ranging unit 70 by the mobile station position extracting unit 106 corresponding to the mobile station position extracting unit. The combination of the positions of the mobile stations 10 in the movable area 50 is extracted and calculated by the existence probability calculation unit 102 by the mobile station position selection unit 108 corresponding to the mobile station position selection unit. A probability evaluation value corresponding to a combination of positions of the plurality of mobile stations 10 extracted by the mobile station position extraction unit 106 is calculated based on the existence probability, and a plurality of mobile stations 10 having the highest probability evaluation value are calculated. The mobile station position correcting unit 110 corresponding to the mobile station position correcting unit selects the positions of the plurality of mobile stations 10 as positioning results by the positioning unit 56 by the mobile station position selecting unit 108. Since the correction is made so as to be a combination of the positions of the mobile stations 10, highly accurate positioning is executed.

  Further, according to the above-described embodiment, the mobile station 10 has the second distance measuring unit 70, and the result of the distance measurement by the second distance measuring unit 70 is a radio wave transmitted by the wireless unit 28 as a transmitting unit. Is transmitted to the mobile station position extraction unit 106 via In this way, since the mobile station 10 has the second distance measuring unit 70, the distance between the mobile station 10 and another mobile station 10 is measured, and the result of the distance measurement is stored in the mobile station 10. Radio waves can be solved by the transmitting unit and transmitted to the mobile station position extracting unit 106.

  Further, according to the above-described embodiment, the positioning server 14 includes the existence probability calculation unit 102, the mobile station position extraction unit 106, the mobile station position selection unit 108, and the mobile station position correction unit 110, so that the position of the mobile station Calculations necessary for the data can be aggregated and executed by the positioning server 14.

  Further, according to the above-described embodiment, the second distance measuring unit 70 includes the sound wave transmitter and the sound wave sensor 72, and performs distance measurement using ultrasonic waves. In this way, since the distance between the specific mobile station 10A and the other mobile station 10B is measured using sound waves whose speed is slower than that of radio waves, it is possible to perform more accurate distance measurement than using radio waves. Become.

  Further, according to the above-described embodiment, the second distance measuring unit 70 includes the image recognition camera 76 and performs distance measurement based on the image captured by the image recognition camera 76. In this way, since the distance between the plurality of mobile stations 10 is measured based on the image captured by the image recognition camera 76, the mobile station 10 does not need to include a sensor or the like.

  Further, according to the above-described embodiment, the second ranging unit 70 includes the specific mobile station 10 </ b> A that is one of the plurality of mobile stations 10 that is to accurately perform position correction, and the positioning unit 56. Thus, the distance from the other mobile station 10B determined to be present at the position closest to the specific mobile station 10A is measured. In this way, the second distance measuring unit 70 measures the distance between the specific mobile station 10A and the other mobile station 10B that is supposed to be located closest to the specific mobile station 10A. Ranging error is reduced.

  Further, according to the above-described embodiment, the mobile station position selection unit 108, when there is a combination of the positions of a plurality of the mobile stations in which the calculated probability evaluation value is within a predetermined range set in advance, A combination of mobile station positions having a high existence probability of the specific mobile station 10A calculated by the existence probability calculation unit 102 is selected. In this way, even when there is a combination of positions of a plurality of mobile stations whose probability evaluation values are within a predetermined range, the existence probability of the specific mobile station 10A calculated by the existence probability calculation unit 102 is high. Since a combination of mobile station positions is selected, the position of the specific mobile station 10A is corrected more accurately.

  Subsequently, another embodiment of the present invention will be described. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 15 is a diagram for explaining selection of a combination of mobile station positions by another method in the mobile station position selection unit 108, and corresponds to FIG. The present embodiment is different in the method of selecting a combination of mobile station positions in the mobile station position selection unit 108, and the configuration and operation other than the mobile station position selection unit 108 are described in the first embodiment. That is, since it is common with FIGS.

The mobile station position selection unit 108 determines the result of positioning by the positioning unit 56 and the existence probability with respect to the combinations of positions that can be taken by the specific mobile station 10A and the other mobile station 10B extracted by the mobile station position extraction unit 106. Based on the existence probability for each base station 10 calculated by the calculation unit 102, the probability evaluation value of the extracted combination is calculated, and the probability evaluation value of the calculated combination is set to the highest probability evaluation value. Select the corresponding combination. Specifically, first, for each base station constituting the combination, its existence probability is calculated based on the relationship shown in FIG. 12, for example, based on the deviation from the positioning result of each base station. Then, the number obtained by multiplying the calculated existence probability of the specific mobile station 10A constituting the combination and the existence probability of each of the other mobile stations 10B is set as the probability evaluation value of the combination. That is, for the combination (xa, xb), if the positioning result is (μa, μb), the existence probability of each mobile station in that case is (fa, fb), and the probability evaluation value of the combination is f. Since fa is a function of a deviation (μa−xa) from the positioning result of the specific mobile station 10A, it is written as fa (μa−xa), and fb is similarly a deviation fb from the positioning result of the other mobile station 10B. It is expressed by (μb−xb). At this time, the probability evaluation value of the combination is f = fa (μa−xa) × fb (μb−xb)
It becomes. In this way, the probability evaluation value f is calculated for a plurality of the combinations, and the combination (xamax, xbmax) corresponding to the probability evaluation value having the maximum value fmax is selected.

  FIG. 15 shows this state with an example of the movable region 50 defined by the straight line. In the figure, the horizontal axis (x-axis) represents the movable region 50, and the vertical axis represents the existence probability. As a result of positioning by the positioning unit 56, it is assumed that the specific mobile station 10A is calculated to exist at the point A1 of x = 8, and the other mobile stations 10B are calculated to exist at the point B1 of x = 18. The relationship between the deviation from the positioning result calculated by the existence probability calculating unit 102 and the existence probability is applied to these positioning results. In the figure, the curves described as the existence probability fa of 10A and the existence probability fb of 10B are those.

  On the other hand, it is assumed that the distance from the specific mobile station 10A measured by the second positioning unit 70 to the other mobile station 10B is L. At this time, the combination of the specific mobile station 10A and the other mobile station 10B extracted by the mobile station position extraction unit 106 has an interval L such as A21 and B21, A22 and B22, or A23 and B23 in the figure. Countless combinations are extracted. Then, for each combination of the specific mobile station 10A and the other mobile station 10B extracted in this way, the existence probability fa corresponding to the position of the specific mobile station 10A and the position of the other mobile station 10B are corresponded. The existence probability fb is calculated, and the calculated fa and fb are multiplied to calculate the probability evaluation value f of the combination.

  The probability evaluation values f corresponding to the combinations calculated in this way are compared, and the combination having the highest value fmax is selected. For example, in FIG. 15, when the specific mobile station 10A is A21 and the other mobile station 10B is B21, and the probability evaluation value f of the combination is maximum, the specific mobile station 10A is A21 and the other mobile station 10B. Is selected from B21.

  When the probability evaluation value f corresponding to each combination calculated by the mobile station selection unit 108 is compared, the probability corresponding to another combination within a predetermined range with the highest value fmax as an upper limit. When the evaluation value f exists, the mobile station selection unit 108 selects a mobile station considering the movement history of the mobile station. This will be specifically described with reference to the example of FIG. For example, the probability evaluation value f21 corresponding to the combination in which the specific mobile station 10A is A21 and the other mobile station 10B is B21, and the combination in which the specific mobile station 10A is A22 and the other mobile station 10B is B22 When the probability evaluation value f22 belongs to a predetermined range Δf, that is, | f11−f22 | <Δf, the movement history of the mobile station is considered.

  Specifically, the movement history of the mobile station is, for example, position information at the time when the specific mobile station 10A was previously positioned. The position of the specific mobile station 10A previously calculated by the positioning system 8 is stored in the positioning result storage unit 112 described later. When the previously calculated position of the specific mobile station 10A is A0, the mobile station selection unit 108 selects a combination including A22 close to the position of the previous specific mobile station 10A among A21 and A22.

  Alternatively, the movement history of the mobile station may be movement information based on a plurality of positioning execution results up to the previous time of the specific mobile station 10A. That is, when positioning is repeatedly performed by the positioning system 8 a plurality of times, the moving speed of the specific mobile station 10A is calculated from the position information of a plurality of times before the previous time, and calculated at the time of the previous positioning execution. Based on the position of the specific mobile station 10A and the calculated movement information, the position of the specific mobile station 10A at the time of the current positioning execution is predicted, and the specific mobile station position 10A close to the predicted position of the specific mobile station 10A is determined. You may make it select the combination to include. Referring to the example of FIG. 15, when the position of the specific mobile station 10A is A0 at the time of the previous positioning execution, and when the position of the specific mobile station 10A is A's at the previous positioning execution, Based on the information, the specific mobile station 10A is predicted to be present in the vicinity of A22 when the current positioning is executed, and as a result, a combination including A22 is selected. On the other hand, when the position of the specific mobile station 10A is A0 at the time of the previous positioning execution, and when the position of the specific mobile station 10A is A'f at the previous positioning execution, based on these information, When performing positioning, the specific mobile station 10A is predicted to exist in the vicinity of A21, and as a result, a combination including A21 is selected.

  Also in the flowchart of FIG. 14, the operation is different for S12 among S10 to S12 corresponding to the mobile station position selection unit 108.

  In S12, the combination of the highest probability evaluation value selected in S10 based on the movement history of the specific mobile station 10A and the other combination in which the probability evaluation value is included in the range Δf in S11. Which one is selected as a combination of mobile station positions is determined. As described above, the movement history includes the specific mobile station 10A based on the presence position of the specific mobile station 10A as the execution result of the previous positioning system 8 or a plurality of execution results up to the previous time of the positioning system 8. Movement information, that is, the current location predicted based on a change in the past location is used.

  The second embodiment can be executed instead of the first embodiment or in addition to the first embodiment.

  According to the above-described embodiment, the mobile station position selection unit 108 moves the mobile station 10 when there is a combination of positions of a plurality of mobile stations 10 in which the calculated probability evaluation value is within a predetermined range Δf set in advance. Based on the movement history of the mobile station 10 before the station position selection unit 108 is executed, a combination of positions of the mobile stations 10 is selected. In this way, even if there is a combination of positions of a plurality of mobile stations 10 whose probability evaluation values are within a predetermined range, the combination of positions of the mobile stations 10 based on the movement history of the mobile station 10 Therefore, a combination of mobile station positions in accordance with the actual mobile station 10 position can be selected.

  Further, according to the above-described embodiment, the movement history of the mobile station 10 is information on the position of the mobile station 10 before the mobile station position selection unit 108 is executed. In this way, since information on the position of the mobile station before execution of the mobile station position selection unit 108 is used as the movement history of the mobile station 10, the combination of the positions of the mobile stations according to the actual position of the mobile station 10 is used. Can be selected.

  Further, according to the above-described embodiment, the movement history of the mobile station 10 is information regarding the movement of the mobile station 10 before the mobile station position selection unit 108 is executed. In this way, since information regarding the movement of the mobile station 10 before the execution of the mobile station position selection unit 108 is used as the movement history of the mobile station 10, the position of the mobile station in accordance with the actual position of the mobile station 10 is used. Can be selected.

  In the first and second embodiments, the case where the movable region 50 is provided in a straight line is taken as an example in order to simplify the description. In this embodiment, the movable area 50 is provided in a plane. In this embodiment, the movable area 50 described in the first and second embodiments is linear, that is, one-dimensional, and the movable area 50 is expanded into a plane, that is, two-dimensional. The configuration of the system 8 and the operation thereof are the same as those in the above-described first and second embodiments, that is, FIGS.

  FIG. 16 is a diagram for explaining selection of combinations of mobile station positions by another method in the mobile station position selection unit 108, and corresponds to FIG. 13 or FIG.

  In FIG. 16, A1 and B1 represented by black circles in the figure are the positioning results of the specific mobile station 10A and the other mobile stations 10B by the distance measuring unit 56, respectively. Further, the mobile station position extraction unit 106 expresses the existence probabilities represented in the vertical axis direction in FIG. 15 in contour lines around the coordinates obtained as the positioning results.

  Further, the distance between the specific mobile station 10 </ b> A and the other mobile station 10 </ b> B measured by the second distance measuring unit 70 is L (m), which is shorter than the distance D calculated by the distance measuring unit 56. ing. Here, the mobile station position extraction unit 106 extracts countless combinations of the positions of the mobile stations 10 whose distance is L in the movable area 50. For example, in FIG. 16, the combination of the position A23 of the specific mobile station 10A and the positions B21, B22, B23, B24, and B25 of the other mobile station 10B connected to each other by the line 90, or the position A21 of the specific mobile station 10A , A22, A23, A24, and A25, and a combination of the position B23 of the other mobile station 10B are extracted.

  Then, the mobile station position selection unit 108 selects the combination having the highest probability evaluation value as the combination of the positions of the mobile stations 10 among the combinations of mobile stations represented by the line 90. In FIG. 16, a combination of mobile station positions represented by a thick line 90b, that is, A23 and B23 are selected. The specific mobile station 10A is located at the position A23 and the other mobile stations 10B are located at the position B23 from the positions A1 and B1 measured by the positioning unit 56 by the mobile station position correction unit 110. It is corrected.

  As described above, the present invention can be applied even when the movable region 50 is given by a plane, and can be similarly applied even when the movable region 50 is given by a three-dimensional space. It is.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the movable area 50, which is an area in which the mobile station 10 can move, is provided as a square plane having a side of 30m, but is not limited thereto. Specifically, the shape is not limited when the movable region 50 is a plane, and the movable region 50 may be provided as a space instead of a plane, and the shape in that case is not limited. If the movable area 50 is provided as a space, the number of base stations necessary for positioning is at least four as described above.

  In the above-described embodiment, the positioning server 14 and each base station 12 are connected by the wired cable 52 to perform communication. However, the communication between the positioning server 14 and each base station 12 is not limited to wired communication. For example, it is possible by radio waves or infrared rays.

  In the above-described embodiment, the balance / unbalance conversion unit 22 provided in the mobile station 10 and the base station 12 is not always necessary, and may have only a function as a matching unit depending on the configuration state of the device. .

  In the above-described embodiment, the direct spreading method is adopted as the method of the spectrum spreading unit 34, but the present invention is not limited to this, and other methods such as UWB (Ultra Wide Band) may be used.

  In the above-described embodiment, the position calculation unit 56 solves the above equation (1) as a simultaneous equation using the Newton-Raphson method or the like, but is not limited to this. An optimal solution may be derived based on this.

  In the above-described embodiment, the distance measuring unit 40 is provided as a function of the base station 12, but is not limited thereto, and may be provided in the positioning server 14, for example. In this case, for example, the signal wave received by the base station 12 may be transmitted from the base station 12 to the positioning server 14 as it is.

  In the above-described embodiment, the second distance measuring unit 70 measures the distance using at least the sound wave transmitter and the sound wave sensor 72 or the image recognition camera 76. However, the second distance measuring unit 70 measures the distance using other means. Also good. In the above-described embodiment, mutual communication between the plurality of mobile stations 10 is not required. However, a distance measuring method used in place of the sound wave transmitter and the sound wave sensor 72 or the image recognition camera 76 is used. If mutual communication between a plurality of mobile stations 10 is required, this may be provided.

  In the above-described embodiment, the mobile station position extraction unit 106 determines that xa is incremented by 1 (m) as (xa, xb) = (0, 11), (1, 12), (2, 13),. However, the present invention is not limited to this. For example, it may be determined based on the accuracy of the distance between the specific mobile station 10A and the other mobile station 10B measured by the second distance measuring unit 70.

  Further, in the first and second embodiments described above, the mobile station position selection unit 108 corresponds to a combination of other mobile stations within a predetermined range Δf with the maximum probability evaluation value corresponding to the combination of mobile stations as an upper limit. However, this is not always necessary, and the combination of the mobile stations 10 having the maximum probability evaluation value is directly used as the combination of the mobile station positions by the mobile station position selection unit 108. It may be selected.

  In the flowchart of FIG. 14, step S7 corresponding to the existence probability calculation unit 102 is executed between S6 and S8. However, the present invention is not limited to this, and the existence probability executed in this step is calculated. Need only be executed before S8. In addition, the standard deviation value calculated in this step may be updated as appropriate, or the previously calculated value may be used without being changed.

  In the above-described embodiment, the positioning unit 56, the mobile station selection unit 104, the existence probability calculation unit 102, the mobile station position extraction unit 106, the mobile station position selection unit 108, the mobile station position correction unit 110, and the positioning result storage unit 112 and the positioning result output unit 60 are provided as functions of the positioning server 14. However, the present invention is not limited to this, and a device other than the positioning server 14, for example, the base station 12 may have a part or all of these functions. Also good.

It is a figure showing an outline of an example of a positioning system to which the present invention is applied. It is a figure explaining the coordinate defined in a movable area | region. It is a functional block diagram showing the outline | summary of the function of the mobile station. It is the figure explaining an example of the shape which a mobile station can take. It is a figure explaining the ranging by the 2nd ranging part at the time of using the camera for image recognition provided in the mobile station. It is a figure explaining the ranging by the 2nd ranging part at the time of using the camera for image recognition provided in the mobile station. It is a functional block diagram showing the outline | summary of the function of the base station. It is a functional block diagram showing the outline | summary of the function of the positioning server. It is a figure for demonstrating the principle of the positioning by a positioning server. It is a time chart explaining an example of the procedure which synchronizes the clock which a base station has. It is a time chart explaining an example of the procedure which measures the distance of each base station and a mobile station. It is a figure showing the relationship between the shift | offset | difference from the measured mobile station position, and existence probability. It is a figure showing the relationship between the position in the movable area | region of several mobile stations, and an existence probability, Comprising: It is a figure explaining selection of the combination of a mobile station based on the existence probability of a specific mobile station by a mobile station position selection part. . It is a flowchart showing the outline | summary of an action | operation of the positioning system of this invention. It is a figure showing the relationship between the position in the movable area | region of a some mobile station, and presence probability, Comprising: It is a figure explaining selection of the combination of the mobile station based on the movement history by a mobile station position selection part. It is a figure showing the relationship between the position in the movable area | region provided on the plane of several mobile stations, and an existence probability, Comprising: It is a figure explaining selection of the combination of the mobile station by a mobile station position selection part.

Explanation of symbols

8: Positioning system 10: Mobile station 12: Base station 14: Positioning server 42: First ranging unit (first ranging unit)
56: Positioning unit 70: Second ranging unit (second ranging unit)
72: Sound wave sensor 76: Image recognition camera 102: Presence probability calculation unit 104: Base station selection unit 106: Mobile station position extraction unit 108: Mobile station position selection unit 110: Mobile station position correction unit

Claims (10)

A plurality of mobile stations having a transmitter that is movable in a predetermined movable area and transmits radio waves;
A receiving unit that receives radio waves transmitted by the plurality of mobile stations, and a first ranging unit that measures distances from the plurality of mobile stations based on the received radio waves, A plurality of base stations fixed to
In a positioning system having a positioning server that has a positioning unit that measures the position of each of the plurality of mobile stations based on distance data measured by the plurality of base stations,
An existence probability calculation unit for calculating an existence probability distribution for the positions of the plurality of mobile stations in the movable region based on a plurality of positioning results by the positioning unit;
A second distance measurement unit that has a higher distance measurement accuracy than the first distance measurement unit and measures a distance between the plurality of mobile stations;
A mobile station position extraction unit that extracts a combination of positions of the plurality of mobile stations in the movable area based on distances between the plurality of mobile stations measured by the second ranging unit;
Based on the existence probability distribution calculated by the existence probability calculation unit, the probability evaluation value corresponding to the combination of the positions of the plurality of mobile stations extracted by the mobile station position extraction unit is calculated, and the most probability evaluation value A mobile station position selection unit that selects a combination of positions of the plurality of mobile stations having a high value;
A mobile station position correction unit that corrects the plurality of mobile station positions, which are positioning results by the positioning unit, so as to be a combination of the positions of the mobile stations selected by the mobile station position selection unit;
A positioning system characterized by having. The mobile station
Having the second distance measuring unit;
The positioning system according to claim 1, wherein a result of ranging by the second ranging unit is transmitted to the mobile station position extracting unit via radio waves transmitted by the transmitting unit. The positioning server
The positioning system according to claim 1, further comprising: the existence probability calculation unit, the mobile station position extraction unit, a mobile station position selection unit, and the mobile station position correction unit. The positioning system according to any one of claims 1 to 3, wherein the second distance measuring unit performs distance measurement using sound waves. The second distance measuring unit includes an image recognition camera, and performs distance measurement based on an image captured by the image recognition camera. Positioning system. The second ranging unit includes a specific mobile station that is one of the plurality of mobile stations that is to accurately perform position correction, and a position closest to the specific mobile station by the positioning unit. The positioning system according to any one of claims 1 to 5, characterized in that a distance to another mobile station that is assumed to exist is measured. The mobile station position selection unit, if there is a combination of the positions of a plurality of the mobile stations where the calculated probability evaluation value is within a predetermined range set in advance, until execution of the mobile station position selection unit Selecting a combination of positions of the mobile stations based on the movement history of the mobile stations in
The positioning system according to any one of claims 1 to 6. The movement history of the mobile station is information on the position of the mobile station before the mobile station position selection unit is executed,
The positioning system according to claim 7. The movement history of the mobile station is information relating to movement of the mobile station before execution of the mobile station position selection unit,
The positioning system according to claim 7. The mobile station position selection unit is calculated by the presence probability calculation unit when there is a combination of a plurality of mobile station positions in which the calculated probability evaluation value is within a predetermined range set in advance. Selecting a combination of positions of the mobile stations with a high probability of existence of the specific mobile station;
The positioning system according to any one of claims 1 to 6.

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