JP2010085290A - Position-detecting apparatus, position detecting system, and position detection method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect, with improved accuracy, the position of a moving object in the exterior of the moving object without providing the moving object with a means for transmitting positioning data. <P>SOLUTION: A position-detecting apparatus includes: a receiving section 11 for receiving a signal containing inherent data transmitted with electric waves from a wireless tag 3 to receive via a network from two or more position measuring devices 2 for detecting the arrival direction of the electric waves the received signal and tag information 31 containing its arrival direction; a position data calculating section 12 for acquiring position data 33 of the wireless tag 3, calculated from the information on the arrival direction and the position of the position-measuring devices 2 for every tag information 31 received in the receiving section 11 from the position measuring devices 2; and a position calculating section 13 for calculating for the tag information 31, containing the same inherent data a weighted average, in which position data 33 calculated from the tag information 31 received at a proximate predetermined time is weighted by a factor, according to the distance from the position measuring device 2, which detects the tag information 31 to a position denoted by the position data 33 of the tag information 31, to calculate a position of the wireless tag 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a position detection device, a position detection system, a position detection method, and a program. More specifically, the present invention relates to position detection that receives a radio wave transmitted from a wireless tag and detects its position.

  As a technique for detecting the position of a moving body, there are a positioning method using GPS (Global Positioning System) and a method of measuring a radio wave transmitted from a terminal such as a mobile phone / PHS from an azimuth and intensity received by a base station.

  Positioning by GPS requires means for transmitting position data to the moving body in order to know the position of the moving body from the outside. In addition, GPS positioning is not possible indoors and underground shopping streets where satellite radio waves do not reach. Positioning by radio waves transmitted from the terminal causes an error due to the influence of multipath and shielding. For example, there are the following techniques for positioning by radio waves transmitted from a terminal.

  Patent Document 1 provides a system in which a transmitter and an MPU are added to a receiver of a wireless system between a receiver and a counting point, and any one of a plurality of transmitters can be used as a counting point. However, a technique that enables high-accuracy position search is described. The technique of Patent Document 1 receives a first signal from an object to be position-detected by wireless communication at a plurality of positions that have been confirmed in advance, and the signal strength level of the first signal and a plurality of known positions are received. The second signal to which the attribute information of the receiver is added is received by wireless communication by a counting device that counts the second signal, and the target object is obtained from the signal strength level of the first signal included in the counted second signal. Specify the position of. And the position of the totalization apparatus which totalizes a 2nd signal can be changed arbitrarily.

  The technique of Patent Document 2 is a position positioning processing method performed by a mobile terminal equipped with a position positioning function for positioning a position. As a method for calculating a positioning processing result, positioning is completed based on a plurality of positioning calculation results. A first processing method for calculating a weighted average value from at least the latest two or more positioning calculation results each time, and a past weighted positioning processing result average every time positioning is completed based on a plurality of positioning calculation results And a second processing method for calculating a weighted average value by adding the latest positioning processing result as a calculation element.

  The technique of Patent Document 3 includes a receiver that receives a first signal from an object to be position-detected and second signals from a plurality of positions whose positions have been confirmed in advance, and a first signal received by the receiver. It is characterized by comprising position detecting means for detecting the position of the object 3 using the first signal and the second signal.

  The position detection system of Patent Document 4 stores a position detection result obtained by calculating a position of a mobile station and a plurality of position detection results obtained before the position detection result, and the position detection result and the previous By comparing the obtained plurality of position detection results, the movement direction of the mobile station is calculated, and the traveling direction obtained by estimating the traveling direction of the mobile station from the calculation results of the plurality of movement directions of the mobile station and A position detection device is provided that detects an abnormal position detection result by comparison with the position detection result.

JP 2006-194735 A JP 2004-233071 A JP 2002-098749 A JP 2001-245335 A

  The technique of Patent Document 1 specifies the position of an object based on the signal strength, but due to the influence of multipath and shielding, if the average is obtained according to the strength of the signals received by a plurality of receivers, it is more than that. Accuracy cannot be obtained. Even in the weighted average or the weighted moving average of Patent Document 2, the error is not always randomly distributed, and the exact position is not known.

  With the technique of Patent Document 4, it is possible to know an abnormal position detection result, but it is not possible to evaluate whether the detected position is correct or an error.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to accurately detect the position outside the moving body without providing a means for transmitting positioning data to the moving body.

A position detection device according to a first aspect of the present invention provides:
A signal including specific data transmitted by radio waves from a radio tag is received, and tag information including the received signal and the arrival direction is received from two or more positioning devices that detect the arrival direction of the radio wave. Receiving means for receiving via,
For each tag information received from the positioning device by the receiving means, position data acquisition means for acquiring the position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information received at the most recent predetermined time is represented by the position data of the tag information from the positioning device that detected the tag information. A position calculating means for calculating a weighted average weighted with a coefficient according to a distance to calculate a position of the wireless tag;
It is characterized by providing.

A position detection system according to a second aspect of the present invention is:
A position detection device according to a first aspect of the present invention;
A signal including specific data transmitted by radio waves from a radio tag is received, the arrival direction of the radio waves is detected, and the received signal and tag information including the arrival direction are transmitted to the position detection device via a network. Two or more positioning devices to send,
It is characterized by providing.

The position detection method according to the third aspect of the present invention is:
Receives a signal containing unique data transmitted from radio tags via radio waves, and receives the received signal and tag information including the direction of arrival via a network from a positioning device that detects the direction of arrival of the radio waves. Receiving step to
For each tag information received from the positioning device in the receiving step, a position data obtaining step for obtaining position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information at the most recent predetermined time from the positioning device that detected the tag information to the position represented by the position data of the tag information A position calculating step of calculating a weighted average weighted by a coefficient according to a distance and calculating a position of the wireless tag;
It is characterized by providing.

The program according to the fourth aspect of the present invention is:
Computer
A signal including specific data transmitted by radio waves from a radio tag is received, and tag information including the received signal and the arrival direction is received from two or more positioning devices that detect the arrival direction of the radio wave. Receiving means for receiving via,
For each tag information received from the positioning device by the receiving means, position data acquisition means for acquiring the position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information at the most recent predetermined time from the positioning device that detected the tag information to the position represented by the position data of the tag information A weighted average weighted by a coefficient corresponding to the distance is calculated and functioned as a position calculating means for calculating the position of the wireless tag.

  According to the present invention, the position can be accurately detected outside the moving body by the radio wave transmitted by the wireless tag included in the moving body.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a position detection system according to Embodiment 1 of the present invention. Referring to FIG. 1, the position detection system 100 includes a position detection device 1, a positioning device 2, and a wireless tag 3. The position detection device 1 is connected to the positioning device 2 via the network N. Further, the position detection device 1 includes an input unit 4 such as a keyboard and an output unit 5 such as a display or a printer.

  The position detection device 1 includes a storage unit 10, a reception unit 11, a position data calculation unit 12, and a position calculation unit 13. The storage unit 10 stores tag information 31, positioning device information 32, position data 33, and position information 34. The position calculation unit 13 includes a weighted average calculation unit 14 and a coefficient calculation unit 15.

  The wireless tag 3 transmits a signal including a unique identification code by radio wave periodically or in response to the radio wave transmitted by the positioning device 2. The positioning device 2 receives a signal transmitted from the wireless tag 3 and detects the arrival direction of the radio wave. In order to detect the arrival direction of radio waves, for example, a plurality of antennas are provided, and the direction in which the phase difference is generated is calculated from the phase difference of signals received by each antenna. Moreover, you may consider the electric field strength of the electromagnetic wave received with each antenna.

  When the positioning device 2 receives the signal transmitted by the wireless tag 3, the positioning device 2 detects the arrival direction, and uses the identification code unique to the wireless tag 3 and data including the arrival direction of the radio wave as tag information to the position detection device 1. Send. The network N connecting the positioning device 2 and the position detection device 1 is not particularly limited as long as tag information can be transmitted to the position detection system 100 at a necessary transmission rate. The network N is, for example, a LAN (Local Area Network). The network N may be a circuit switching network, a packet switching network, the Internet, or a private line network. Further, the network N is not limited to a wired line, and may be a wireless communication network such as a wireless LAN. For example, short-range wireless communication such as ZigBee (registered trademark) and Bluetooth (registered trademark) can be used.

  The receiving unit 11 of the position detection device 1 receives tag information transmitted from the positioning device 2 and stores it as tag information 31 in the storage unit 10. The position data calculation unit 12 calculates the position of the wireless tag 3 represented by the coordinates of each positioning device 2 that has detected the tag information from the tag information 31 and the positioning device information 32.

  FIG. 2 is a schematic diagram showing the positional relationship between the positioning device 2 and the wireless tag 3. 2A is a plan view, and FIG. 2B is a side view of a plane including a straight line in the arrival direction. The positioning device 2 is installed at a height H from the ground surface E. When the wireless tag 3 is carried by a person, it can be assumed that the wireless tag 3 is in a plane F parallel to the ground surface E at a height h from the ground surface. When the arrival direction of the radio wave is represented by the azimuth angle θ and the zenith angle φ, the point where the straight line of the arrival direction intersects the surface F having the height h is estimated as the position of the wireless tag 3. Assume a coordinate system xyz with the positioning device 2 as the origin. Local coordinates (x, y, z) in which the intersection point is expressed in the coordinate system xyz are set as position data.

  FIG. 3 shows an example of the tag information 31. The tag information 31 includes the identification code (positioner ID) of the positioning device 2 that detected it, the identification code (tag ID) specific to the tag included in the signal, the azimuth and zenith angles that are the arrival directions of radio waves, and the reception Includes time. Further, received field strength (RSSI) may be included. The azimuth angle is an angle in a horizontal plane from a certain direction defined by the positioning device 2. The zenith angle is an angle from above the vertical line passing through the positioning device 2. Instead of the zenith angle, the dip angle or elevation angle from the horizontal plane may be used. The arrival direction may be given by a direction cosine.

  FIG. 4 shows an example of the positioning device information 32. The positioning device information 32 includes the positioning device ID, the longitude (Lon) of the positioning device 2, the latitude (Lat), the ground height H, and the orientation of the positioning device 2. When the positioning device 2 is always installed in a certain direction, for example, the reference line is facing north, the direction is constant and may be omitted from the positioning device information 32. When the positioning device 2 is not distributed over a wide range but is installed in a limited region, the position of the positioning device 2 can be represented by coordinates in the region instead of longitude and latitude.

  The position data calculation unit 12 shown in FIG. 1 includes a tag information 31 as shown in FIG. 3 and a positioning device information 32 as shown in FIG. The position of the wireless tag 3 is calculated from the coordinates. Here, in order to facilitate understanding, the range represented by local coordinates is assumed to be a horizontal plane. However, when the positioning device 2 is installed on a slope, it is wireless from a slope to a certain height h. Assuming that the tag 3 is located, position data is calculated. In that case, the position data includes coordinate values of height.

  FIG. 5 shows an example of the position data 33. The position data 33 includes a local x coordinate and a local y coordinate represented by local coordinates associated with the positioning device 2 with respect to the time when the tag information 31 is received, the positioning device ID, and the tag ID. In addition, local z coordinates may be included.

The position calculation unit 13 in FIG. 1 calculates a more accurate position of the wireless tag 3 from the position data 33 and the positioning device information 32. Of the position calculation unit 13, the coefficient calculation unit 15 calculates a weighting coefficient for each tag information 31 from the position data 33. The weighting coefficient αjk for each tag information 31 is given by the following equation.
^{Ljk = SQRT (xjk 2 + yjk} 2)
αjk = Ljk ²
Where SQRT represents the (positive) square root. The suffix j represents the number of the positioning device 2. The suffix k represents the number of the tag information 31 having the same tag ID. The coordinates (xjk, yjk) represent a position in local coordinates with the positioning device 2 that detected the tag information 31 as the origin. Ljk is the distance between the position of the wireless tag 3 and the positioning device 2 that has detected the tag information 31.

  Here, in order to facilitate understanding, the value of the z coordinate is omitted. If the height in the z direction is not negligible compared to the distance Ljk, the distance Ljk including zjk is calculated. zjk is Hh in the example of FIG. The coefficients in FIG. 5 are weighting coefficients represented by the above formula.

The weighted average calculation unit 14 in FIG. 1 calculates the position of the wireless tag 3 in the global coordinates using the position data 33, the positioning device information 32, and the weighting coefficient. The position obtained by converting the local coordinate position (xjk, yjk) for each positioning device 2 into the global coordinates common to all positioning devices is defined as (Xi, Yi), and the position of the wireless tag 3 at the time of interest is expressed as X = Σ (αi・ Xi) / Σ (αi)
Y = Σ (αi · Yi) / Σ (αi)
Calculate with Similarly, the Z coordinate may be calculated. Here, Σ represents the sum of i in a predetermined period. i represents the number of the tag information 31 included in the predetermined period nearest to the tag of interest. The predetermined period for calculating the weighted average takes into account the period at which the wireless tag 3 transmits a signal, the moving speed of the wireless tag 3, the resolution of the positioning device 2, the number of positioning devices 2 that simultaneously receive the signals of the wireless tag 3, and the like. And set.

  The weighted average weighting coefficient is the reciprocal of the square of the distance between the position represented by the position data 33 of the wireless tag 3 and the positioner 2 that detected it. Accordingly, the coordinates (X, Y) of the position information represented by the weighted average is a value obtained by evaluating the tag information 31 of the positioning device 2 close to the wireless tag 3 more greatly. As the distance between the wireless tag 3 and the positioning device 2 increases, the ratio of the electric field between the direct wave and the reflected wave (or diffracted wave) decreases, so that the error of the position data 33 increases. By accurately evaluating the data of the positioning device 2 close to the wireless tag 3, the accuracy of the calculated position is increased.

  The position data 33 included in the weighted average can include the value of the tag information 31 received from the plurality of positioning devices 2. The weighted average may include two or more tag information 31 received from one positioning device 2. There is no corresponding tag information 31 from a certain positioning device 2, and it may not be included in the weighted average. When one transmission packet transmitted by a certain tag is received by a plurality of positioning devices 2, (Xi, Yi) may include position information calculated from the plurality of tag information 31.

  The weighted average calculation unit 14 stores the calculated position of the wireless tag 3 as the position information 34 in the storage unit 10. FIG. 6 shows an example of the position information 34. The position information 34 includes time, tag ID, X coordinate, and Y coordinate (or longitude and latitude).

  The position detection device 1 displays the calculated position of the wireless tag 3 on the output unit 5 in accordance with a command input from the input unit 4. For example, the position of the target wireless tag 3 is displayed on the map every moment. Alternatively, the distribution of the wireless tag 3 at a certain time can be displayed.

  FIG. 7 is a flowchart showing an example of the operation of the position detection process according to the first embodiment. When the receiving unit 11 receives the tag information 31 (step S11), the position data calculating unit 12 calculates the position data 33 from the radio wave arrival direction of the tag information 31 and the information of the positioning device 2 (step S12).

  The coefficient calculation unit 15 calculates a weighting coefficient corresponding to the distance between the positioning device 2 and the position represented by the position data 33 (step S13). The position calculation unit 13 lists the position data 33 having the same unique ID for a predetermined period (step S14). Then, the position data 33 and the positioning device information 32 listed are converted into global coordinate positions (step S15).

  The weighted average calculation unit 14 calculates a weighted average using the position of the global coordinates and the weighting coefficient calculated by the coefficient calculation unit 15 (step S16). Then, the calculated position of the wireless tag 3 is stored in the storage unit 10 as position information 34 (step S17). The position detection device 1 repeats the above operation from the reception of the tag information (step S11).

  As described above, according to the position detection device of the present embodiment, the position can be accurately detected outside the moving body by the radio wave transmitted from the wireless tag 3 provided in the moving body.

  The weighting coefficient is not calculated for each position data 33, but is calculated for the average of the position data 33 for each positioning device 2 for a predetermined period for the wireless tag 3, and the value is applied to the next predetermined period. It is also possible to do it. The average of the position data 33 for a predetermined period may be used as a moving average.

(Modification of Embodiment 1)
In the first embodiment, the position of the wireless tag 3 is calculated by the weighted average from the position data 33 of the most recent predetermined period using a weighting coefficient that is inversely proportional to the square of the distance between the wireless tag 3 and the positioning device 2. For simplicity, the position information 34 may be calculated using the position data 33 having the maximum weighting coefficient in the most recent predetermined period instead of the weighted average.

  This is to calculate the above-mentioned weighted average by setting the coefficient to 1 for the position data 33 having the largest weighting coefficient in the most recent predetermined period and setting the coefficients of the other position data 33 to 0. Equivalent to.

  In the method of using the position data 33 having the maximum weighting coefficient value, the maximum value of the error is larger than that of the weighted average, but on the average, a value not significantly different from the position information 34 calculated by the weighted average is obtained. Since the weighted average is not actually calculated and only the position data 33 having the maximum coefficient is adopted and converted into the global coordinates, the calculation amount can be reduced.

(Embodiment 2)
FIG. 8 is a block diagram showing a configuration example of the position detection system according to Embodiment 2 of the present invention. The position detection device 1 according to the second embodiment includes an RSSI filter 17, a velocity filter 18, and a range filter 19 in addition to the configuration of the first embodiment shown in FIG. Further, the storage unit 10 includes an electric field threshold value 35, a movement threshold value 36, and range information 37. Other configurations are the same as those of the first embodiment.

  In the second embodiment, the tag information 31 is screened according to the received electric field strength, and the tag information 31 that is not included in the position calculation is excluded. Further, the position data 33 representing the position that cannot be actually generated is excluded from the position calculation. Further, the position data 33 exceeding the detection range of the positioning device 2 is excluded from the position calculation.

  In the second embodiment, the received electric field strength (RSSI) detected by the positioning device 2 is included in the tag information 31 transmitted by the positioning device 2. The RSSI filter 17 excludes the tag information 31 whose received electric field strength RSSI is a predetermined value or less from the position data calculation. The position data calculation unit 12 calculates position data 33 for the tag information 31 that has passed through the RSSI filter 17.

  The speed filter 18 determines whether or not the latest position data 33 is within a predetermined range from the latest position data 33 for each wireless tag 3 and each positioner 2. When the value obtained by dividing the movement amount of the position represented by the latest position data 33 by the time exceeds the assumed range, the position data 33 is excluded from the position calculation. That is, when the position data 33 indicates a position that cannot be reached unless the moving body holding the wireless tag 3 greatly exceeds the normal speed, the position data 33 is excluded.

  FIG. 9 shows an example of the threshold value of the received electric field strength and the threshold value of the moving speed. “Electric field threshold” indicates a threshold of received electric field strength. The “movement threshold value” indicates a threshold value of movement speed. In the example of FIG. 9, those threshold values are set for each identification code of the positioning device 2. The electric field strength to be received also depends on the distribution of the positioning device 2. In addition, the limit of the received electric field intensity that can correctly detect the arrival direction of the radio wave may vary depending on the conditions around the positioning device 2. The threshold value of the received electric field strength may be set uniformly by the position detection system 100.

  The threshold value of the moving speed is also set for each positioning device 2 in the example of FIG. The maximum speed of the moving body can vary depending on the location where the positioning device 2 is installed. For example, the maximum speed changes depending on whether walking alone, movement by bicycle, or the like is possible, or whether intense exercise is assumed. Accordingly, a threshold value for the moving speed may be set for each positioning device 2. The threshold value of the moving speed may be set uniformly by the position detection system 100.

  It is desirable that the speed filter 18 does not compare the latest position data 33 with only the immediately preceding position data 33 but with a plurality of the latest position data 33. For example, a comparison is made with the moving average of the most recent position data 33. In some cases, it is impossible to determine which one is close to the true position only with the immediately preceding one position data 33. When the position data 33 for a certain positioning device 2 is small and the amount of movement exceeds the threshold, the screening is suspended, and after the position data 33 increases, a group is adopted, The position data 33 that is separated by one point may be excluded.

  The range filter 19 of FIG. 8 excludes the position data 33 from the position calculation when the position of the position data 33 is outside the range determined for each positioning device 2. The range for each positioning device 2 is a limit that the mobile body can reach or a limit that the positioning device 2 should detect. For example, there is a case where it is limited by a cliff or a step and the destination cannot be reached. Moreover, the boundary of the place where the mobile body holding the wireless tag 3 cannot enter may be indicated.

  The limit to be detected by the positioning device 2 includes the case where the positioning device 2 has directivity and the case where the range to be detected by being installed on a wall surface is limited. In addition, when there are a large number of positioning devices 2 within a range that can be detected by a certain positioning device 2 due to the distribution of the positioning devices 2, a range that does not need to be detected is set, and data in a range where errors are assumed to be large May be excluded from the beginning. In that case, the boundary may include an arc having a predetermined radius centered on the positioning device 2.

  FIG. 10 shows an example of data for setting a target range for each positioning device 2. As described above, the target range is set for each positioning device 2. In the example of FIG. 10, the upper limit Ux and lower limit Lx of the x coordinate, the upper limit Uy and lower limit Ly of the y coordinate, and the boundary line are set in the local coordinate system having the positioning device 2 as the origin. The boundary line is expressed by a function of local coordinates, for example. In the example of FIG. 10, a circle with a radius r1 and a circle with a radius r2 are set. When the target range for each positioning device 2 includes an arc, when the coefficient calculation unit 15 calculates the weighting coefficient, the square of the distance is calculated, and at that time, the position data 33 outside the range can be excluded. .

  By providing the RSSI filter 17, the speed filter 18, and the range filter 19, the tag information 31 and the position data 33 that are estimated to have a large error can be excluded from the position calculation. As a result, a more accurate value is obtained as the position of the wireless tag 3 calculated by the position calculation unit 13.

  In the first and second embodiments, all the positioning devices 2 are equivalent, and a configuration is assumed in which a signal transmitted by the wireless tag 3 is simply received and the arrival direction of the radio wave is detected. A configuration in which a part of the function of the position detection device 1 is provided in the positioning device 2 is also possible. For example, the RSSI filter 17 may be provided in the positioning device 2 so that only a signal having a predetermined electric field strength or more is transmitted to the position detection device 1. In addition, the positioning device 2 may have a part of the function of the range filter 19. A range of radio wave arrival directions (azimuth angle and zenith angle) can be set for each positioning device 2 so that only signals within the range of the detected arrival direction are transmitted to the position detection device 1.

  FIG. 11 is a flowchart illustrating an example of the operation of the position detection process according to the second embodiment. The operation of FIG. 11 is configured by adding the operations of the RSSI filter 17, the speed filter 18, and the range filter 19 to the operation of FIG. The same processing steps as those in the first embodiment are denoted by the same reference numerals.

  When the receiving unit 11 receives the tag information 31 (step S11), the RSSI filter 17 determines whether or not the received electric field strength included in the tag information 31 is greater than a threshold value (step S21). If the received electric field strength is larger than the threshold value (step S21; YES), the position data 33 is calculated (step S12). If the received electric field strength is less than or equal to the threshold value (step S21; NO), the tag information 31 is excluded from the position calculation (step S31). And it returns to tag information reception (step S11), and repeats operation | movement.

  The position data calculation unit 12 calculates the position data 33 from the radio wave arrival direction of the tag information 31 and the information of the positioning device 2 (step S12). The range filter 19 determines whether or not the position of the position data 33 is within the range set in the positioning device 2 (step S22). If the position is within the predetermined range (step S22; YES), the moving speed is calculated (step S23). If the position exceeds the predetermined range (step S22; NO), the tag information 31 is excluded from the position calculation (step S31), and the process returns to tag information reception (step S11).

  The speed filter 18 calculates the moving speed of the latest position data 33 from the latest position data 33 for each wireless tag 3 and for each positioning device 2 (step S23), and the value is within a predetermined range. Is determined (step S24). If the moving speed is less than the specified value (step S24; YES), a weighting coefficient is calculated (step S13). If the moving speed is equal to or higher than the specified value (step S24; NO), the tag information 31 is excluded from the position calculation (step S31), and the process returns to tag information reception (step S11).

  After the weighting coefficient is calculated (step S13), the processing is the same as that of the first embodiment (step S14 to step S17).

  In addition, in the process of FIG. 11, the structure which performs the process of the range filter 19 before the speed filter process (step S23, step S24) was demonstrated. As described above, the processing of the range filter 19 may be performed after the processing of the velocity filter 18 is performed.

  As described above, according to the position detection apparatus of the second embodiment, the tag information 31 and the position data 33 that are estimated to have a large error can be excluded from the position calculation. As a result, a more accurate value is obtained as the position of the wireless tag 3 calculated by the position calculation unit 13.

  Note that the RSSI filter 17, the speed filter 18 and the range filter 19 may not be provided all at the same time. Since each functions independently, it can be set as the structure arbitrarily combined according to the position detection of the object. A configuration without the RSSI filter 17 is equivalent to the threshold value of the RSSI filter being zero. The configuration without the speed filter 18 can be regarded as the same as the movement speed threshold value being extremely large. When the range filter 19 is not provided, it can be considered that the target range is equal to or greater than the detection limit of the positioning device 2.

  FIG. 12 is a block diagram illustrating an example of a hardware configuration of the position detection device 1 illustrated in FIG. 1 or 8. As illustrated in FIG. 12, the position detection device 1 includes a control unit 21, a main storage unit 22, an external storage unit 23, an operation unit 24, a display unit 25, and a transmission / reception unit 26. The main storage unit 22, the external storage unit 23, the operation unit 24, the display unit 25, and the transmission / reception unit 26 are all connected to the control unit 21 via the internal bus 20.

  The control unit 21 includes a CPU (Central Processing Unit) and the like, and executes the processing of the position detection device 1 according to the program 30 stored in the external storage unit 23.

  The main storage unit 22 is composed of a RAM (Random-Access Memory) or the like, loads a program 30 stored in the external storage unit 23, and is used as a work area of the control unit 21.

  The external storage unit 23 includes a non-volatile memory such as a flash memory, a hard disk, a DVD-RAM (Digital Versatile Disc Random-Access Memory), a DVD-RW (Digital Versatile Disc ReWritable), etc. A program 30 to be executed is stored in advance, and data stored by the program is supplied to the control unit 21 according to an instruction from the control unit 21 and the data supplied from the control unit 21 is stored. The storage unit 10 in FIG. 1 or 8 is configured in the external storage unit 23. When the position detection process is performed, a part of the data is stored in the main storage unit 22 and used for the operation of the control unit 21.

  The operation unit 24 includes a pointing device such as a keyboard and a mouse, and an interface device that connects the keyboard and the pointing device to the internal bus 20. The identification code of the wireless tag 3 for detecting the position and information on the positioning device 2 are input via the operation unit 24 and supplied to the control unit 21. In addition, a command for displaying the result of position detection is input. The operation unit 24 corresponds to the input unit 4 in FIG. 1 or FIG.

  The display unit 25 is configured by a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display) or the like, and displays information on the positioning device 2, the position of the detected wireless tag 3, and the like. The display unit 25 is an example of the output unit 5 in FIG. 1 or FIG. In addition, the output unit 5 may include a printer.

  The transmission / reception unit 26 receives the tag information 31 from the positioning device 2 via the network N. Moreover, the command which diagnoses the state of the positioning device 2 is transmitted. A threshold value of the received electric field strength may be transmitted to the positioning device 2. The transmission / reception unit 26 constitutes the reception unit 11 of FIG. 1 or FIG.

  The processing of the receiving unit 11, the position data calculating unit 12, the position calculating unit 13, the weighted average calculating unit 14, the coefficient calculating unit 15, the RSSI filter 17, the speed filter 18, and the range filter 19 shown in FIG. The control unit 21, the main storage unit 22, the external storage unit 23, the operation unit 24, the display unit 25, the transmission / reception unit 26, and the like are used as resources for processing.

(Example)
13A to 15D show the results of actually detecting the position of the wireless tag 3 by arranging a plurality of positioning devices 2 at a certain place. 13A and 13B show values obtained by simply moving and averaging the position data 33. FIG. The position data 33 calculated by the moving average is represented by small diamond points. FIG. 13A shows moving average data of three points. The actual walking route is represented by a large square point. FIG. 13B shows moving average data of 8-point position data 33 detected by four positioning devices 2. The route actually walked is represented by a triangular point.

  As shown in FIGS. 13A and 13B, the position calculated by the moving average is considerably biased inward compared to the walking route. The difference is particularly large at the four corners outside the walking path.

  14A to 14D show the results of calculating the moving average of the position data 33 for each positioning device 2. Each actual walking route is represented by a large square point. The moving average value is represented by small diamond points. FIG. 14A is a moving average of the position data 33 detected by the positioning device 2 arranged on the negative axis of the horizontal axis in the figure. FIG. 14B is a moving average of the position data 33 detected by the positioning device 2 arranged on the negative axis of the vertical axis in the drawing. FIG. 14C is a moving average of the position data 33 detected by the positioning device 2 arranged on the positive axis of the horizontal axis in the drawing. FIG. 14D is a moving average of the position data 33 detected by the positioning device 2 arranged on the positive axis of the vertical axis in the drawing. Each is a moving average of 8 points.

  As shown in FIGS. 14A to 14D, the positions calculated by the moving average of the position data 33 for each positioning device 2 appear toward the positioning device 2 in a biased manner. The error is large for a walking point far from the positioning device 2.

  15A to 15D show the results of calculating the position by the method of the present invention while changing the length of the predetermined period. The arrangement of the positioning device 2 and the walking route are the same as those in FIGS. 14A to 14D. 15A shows a subdivision designation section (a period for which a weighted average is calculated) is 100 msec, FIG. 15B shows a subdivision designation section of 300 msec, FIG. 15C shows a subdivision designation section of 500 msec, and FIG. The section is 1000 msec. A cycle for transmitting a signal from the wireless tag 3 is 170 msec. In either case, the calculated result is represented by a small diamond point, and the actual walking route is represented by a large square point.

  As shown in FIGS. 15A to 15D, the position calculated by the method of the present invention is not biased toward any positioning device 2, and is not significantly smaller than the actual walking route. Compared to FIGS. 13A to 14D, it is close to the actual walking route, and it can be said that the position detection accuracy is high. This is because the weighted average works so that the data of the positioning device 2 close to the wireless tag 3 is emphasized and the fluctuation is corrected by the data of the positioning device 2 far away.

  Other suitable modifications of the present invention include the following configurations.

About the position detection device according to the first aspect of the present invention,
Preferably, the position calculation means uses the inverse of the square of the distance from the positioner that has detected the tag information to the position represented by the position data of the tag information as a coefficient corresponding to the distance, and calculates the weighted average. It is characterized by calculating.

  Alternatively, the position calculating means calculates a coefficient corresponding to the distance at a shortest predetermined time from a positioning device that has detected the tag information to a position represented by the position information of the tag information. The weighted average may be calculated by setting the value to 1 and setting the remaining tag information for the most recent predetermined time to 0.

Preferably, the distance between the position represented by the latest position information of the tag information and the position represented by the position data of the tag information having the same specific number of the most recent specific data is a predetermined value. A speed filter that excludes the latest tag information from the target of the position calculation means when exceeding,
The position calculation means calculates the weighted average without including the position data of the tag information excluded by the speed filter.

Preferably, when the position represented by the position data of the tag information exceeds a predetermined range from the positioning device that detected the tag information, the latest tag information is excluded from the position calculation means. With a range filter,
The position calculation means calculates the weighted average without including the position data of the tag information excluded by the range filter.

  The range filter may include a portion at a certain distance from the positioning device that has detected the tag information in a predetermined range that is excluded from the target of the position calculation means.

Preferably, the reception field strength for receiving a signal including specific data transmitted by radio waves from the wireless tag is acquired, and tag information whose reception field strength is a predetermined value or less is excluded from the target of the position calculation means. An RSSI filter
The position calculating means calculates the weighted average without including the position data of the tag information excluded by the RSSI filter.

About the position detection method according to the third aspect of the present invention,
Preferably, in the position calculation step, the weighted average is calculated using a reciprocal of the square of the distance from the positioning device that has detected the tag information to the position represented by the position data of the tag information as a coefficient corresponding to the distance. It is characterized by calculating.

  Alternatively, in the position calculating step, the coefficient corresponding to the distance is the minimum distance from the positioning device that has detected the tag information to the position represented by the position data of the tag information at the nearest predetermined time. May be set to 1, and the remaining tag information for the most recent predetermined time may be set to 0 to calculate the weighted average.

Preferably, the distance between the position represented by the latest position information of the tag information and the position represented by the position data of the tag information having the same specific number of the most recent specific data is a predetermined value. A speed excluding step of excluding the latest tag information from the target of the position calculating step when exceeding,
In the position calculating step, the weighted average is calculated without including the position data of the tag information excluded in the speed excluding step.

Preferably, when the position represented by the position data of the tag information exceeds a predetermined range from the positioning device that has detected the tag information, the latest tag information is excluded from the target of the position calculation step. With a range exclusion step,
In the position calculating step, the weighted average is calculated without including the position data of the tag information excluded in the range excluding step.

  The range exclusion step may include a portion at a certain distance from the positioning device that has detected the tag information in a predetermined range that is excluded from the target of the position calculation step.

Preferably, the reception field strength for receiving a signal including unique data transmitted by radio waves from the wireless tag is acquired, and tag information whose reception field strength is a predetermined value or less is excluded from the target of the position calculation step. An electric field strength exclusion step
In the position calculating step, the weighted average is calculated without including the position data of the tag information excluded in the electric field strength excluding step.

  In addition, the hardware configuration and the flowchart described above are merely examples, and can be arbitrarily changed and modified.

  The central part that performs processing of the position detection device 1 including the control unit 21, the main storage unit 22, the external storage unit 23, the operation unit 24, the internal bus 20, and the like is not a dedicated system, but a normal computer It can be realized using the system. For example, the program 30 for executing the above operation is stored and distributed on a computer-readable recording medium (flexible disk, CD-ROM, DVD-ROM, etc.), and the computer program is installed in the computer. Thus, the position detection device 1 that executes the above-described processing may be configured. Alternatively, the computer program may be stored in a storage device included in a server device on a communication network such as the Internet, and the position detection device 1 may be configured by being downloaded by a normal computer system.

  Further, when the function of the position detection device 1 is realized by sharing of an OS (operating system) and an application program, or by cooperation between the OS and the application program, only the application program portion is stored in a recording medium or a storage device. May be.

  It is also possible to superimpose a computer program on a carrier wave and distribute it via a communication network. For example, the program 30 may be posted on a bulletin board (BBS: Bulletin Board System) on a communication network, and the program 30 may be distributed via the network. And you may comprise so that the said process can be performed by starting the program 30 and performing similarly to another application program under control of OS.

It is a block diagram which shows the structural example of the position detection system which concerns on Embodiment 1 of this invention. It is a schematic diagram showing the positional relationship between a positioning device and a wireless tag. It is a figure which shows the example of tag information. It is a figure which shows the example of positioning device information. It is a figure which shows the example of position data. It is a figure which shows the example of position information. 6 is a flowchart illustrating an example of an operation of position detection processing according to the first embodiment. It is a block diagram which shows the structural example of the position detection system which concerns on Embodiment 2 of this invention. It is a figure which shows the example of the threshold value of a received electric field, and the threshold value of moving speed. It is a figure which shows the example of the data which set the target range for every positioning device. 10 is a flowchart illustrating an example of an operation of position detection processing according to the second embodiment. It is a block diagram which shows an example of the hardware constitutions of a position detection apparatus. It is a figure which shows the value which carried out the moving average of the position data of 3 points | pieces. It is a figure which shows the value which carried out the moving average of the position data of 8 points | pieces. It is a figure which shows the result of having calculated the moving average of the position data detected with the positioning device on a negative horizontal axis. It is a figure which shows the result of having calculated the moving average of the position data detected with the positioning device on a negative vertical axis | shaft. It is a figure which shows the result of having calculated the moving average of the position data detected with the positioning device on a positive horizontal axis. It is a figure which shows the result of having calculated the moving average of the position data detected with the positioning device on the positive vertical axis. It is a figure which shows the example of the weighted average in case a subdivision designation | designated area is 100 msec. It is a figure which shows the example of the weighted average in case a subdivision designation | designated area is 300 msec. It is a figure which shows the example of the weighted average in case a subdivision designation | designated area is 500 msec. It is a figure which shows the example of the weighted average in case a subdivision designation | designated area is 1000 msec.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Position detection apparatus 2 Positioning device 3 Wireless tag 4 Input part 5 Output part 10 Storage part 11 Reception part 12 Position data calculation part 13 Position calculation part 14 Weighted average calculation part 15 Coefficient calculation part 17 RSSI filter 18 Speed filter 19 Range filter 21 Control unit 22 Main storage unit 23 External storage unit 24 Operation unit 25 Display unit 26 Transmission / reception unit 30 Program 31 Tag information 32 Positioning device information 33 Position data 34 Position information 35 Electric field threshold 36 Moving threshold 37 Range information 100 Position detection system

Claims (16)

A signal including specific data transmitted by radio waves from a radio tag is received, and tag information including the received signal and the arrival direction is received from two or more positioning devices that detect the arrival direction of the radio wave. Receiving means for receiving via,
For each tag information received from the positioning device by the receiving means, position data acquisition means for acquiring the position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information received at the most recent predetermined time is represented by the position data of the tag information from the positioning device that detected the tag information. A position calculating means for calculating a weighted average weighted with a coefficient according to a distance to calculate a position of the wireless tag;
A position detection device comprising:   The position calculating means calculates the weighted average using a reciprocal of the square of the distance from the positioning device that has detected the tag information to the position represented by the position data of the tag information as a coefficient corresponding to the distance. The position detection device according to claim 1.   The position calculating means has a coefficient corresponding to the distance, which has a minimum distance from the positioning device that has detected the tag information to the position represented by the position data of the tag information at the most recent predetermined time. 2. The position detecting apparatus according to claim 1, wherein the weighted average is calculated by setting the tag information to 1 and setting the remaining tag information of the most recent predetermined time to 0. When the distance between the position represented by the latest position information of the tag information and the position represented by the position data of the tag information having the same specific data of the most recent predetermined number exceeds a predetermined value And a speed filter for excluding the latest tag information from the target of the position calculating means,
The position calculation means calculates the weighted average without including the position data of the tag information excluded by the speed filter;
The position detection device according to claim 1, wherein the position detection device is a first position detection device. A range filter that excludes the latest tag information from the position calculation means when the position represented by the position data of the tag information exceeds a predetermined range from the positioning device that detected the tag information. Prepared,
The position calculating means calculates the weighted average without including the position data of the tag information excluded by the range filter;
The position detection device according to claim 1, wherein the position detection device is a first position detection device.   6. The position detection apparatus according to claim 5, wherein the range filter includes a predetermined range that excludes a portion at a certain distance from the positioning device that has detected the tag information from the target of the position calculation unit. . An RSSI filter that obtains a received electric field strength for receiving a signal including specific data transmitted by radio waves from the wireless tag, and excludes tag information whose received electric field strength is a predetermined value or less from the target of the position calculating means With
The position calculating means calculates the weighted average without including the position data of the tag information excluded by the RSSI filter;
The position detection device according to claim 1, wherein The position detection device according to any one of claims 1 to 7,
A signal including specific data transmitted by radio waves from a radio tag is received, the arrival direction of the radio waves is detected, and the received signal and tag information including the arrival direction are transmitted to the position detection device via a network. Two or more positioning devices to send,
A position detection system comprising: Receives a signal containing unique data transmitted from radio tags via radio waves, and receives the received signal and tag information including the direction of arrival via a network from a positioning device that detects the direction of arrival of the radio waves. Receiving step to
For each tag information received from the positioning device in the receiving step, a position data obtaining step for obtaining position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information at the most recent predetermined time from the positioning device that detected the tag information to the position represented by the position data of the tag information A position calculating step of calculating a weighted average weighted by a coefficient according to a distance and calculating a position of the wireless tag;
A position detection method comprising:   The position calculating step calculates the weighted average using a reciprocal of the square of the distance from the positioning device that has detected the tag information to the position represented by the position data of the tag information as a coefficient corresponding to the distance. The position detection method according to claim 9.   In the position calculating step, a coefficient corresponding to the distance is set to a value having a minimum distance from a positioning device that has detected the tag information to a position represented by position data of the tag information at a predetermined predetermined time. The position detection method according to claim 9, wherein the weighted average is calculated by setting the remaining tag information for the most recent predetermined time to 0 and setting the remaining tag information to 0. When the distance between the position represented by the latest position information of the tag information and the position represented by the position data of the tag information having the same specific data of the most recent predetermined number exceeds a predetermined value And a speed excluding step of excluding the latest tag information from the target of the position calculating step,
The position calculating step calculates the weighted average without including the position data of the tag information excluded in the speed excluding step;
The position detection method according to claim 9, wherein Range exclusion step of excluding the latest tag information from the position calculation step target when the position represented by the position data of the tag information exceeds a predetermined range from the positioning device that detected the tag information With
The position calculating step calculates the weighted average without including the position information of the tag information excluded in the range excluding step;
The position detection method according to claim 9, wherein   The position detection according to claim 13, wherein the range exclusion step includes a portion of a certain distance from the positioning device that has detected the tag information in a predetermined range that is excluded from the target of the position calculation step. Method. An electric field strength for acquiring a received electric field strength for receiving a signal including specific data transmitted by radio waves from the wireless tag and excluding tag information whose received electric field strength is a predetermined value or less from the target of the position calculating step. With an exclusion step,
The position calculating step calculates the weighted average without including the position information of the tag information excluded in the electric field strength excluding step.
The position detecting method according to claim 9, wherein the position detecting method is one of the following. Computer
A signal including specific data transmitted by radio waves from a radio tag is received, and tag information including the received signal and the arrival direction is received from two or more positioning devices that detect the arrival direction of the radio wave. Receiving means for receiving via,
For each tag information received from the positioning device by the receiving means, position data acquisition means for acquiring the position data of the wireless tag calculated from the arrival direction and the position information of the positioning device;
For the tag information including the same unique data, the position data calculated from the tag information at the most recent predetermined time from the positioning device that detected the tag information to the position represented by the position data of the tag information A program for calculating a weighted average weighted by a coefficient corresponding to a distance and causing the position of the wireless tag to be calculated.

Images