JP6415395B2 - Electronic device, position specifying program and position specifying method - Google Patents

Description

  The present invention relates to an electronic apparatus having a navigation function, and more particularly to a method for specifying a current location based on radio waves received from a plurality of stations.

  In a navigation function of an electronic device such as a car navigation device or a smartphone, a current location is calculated by a current location calculation means such as GPS (Global Positioning System), and a guidance route to a destination is calculated. Further, a method for calculating the position of the electronic device by a method other than GPS is disclosed.

  Patent Document 1 discloses a position calculation method for calculating the current position of a PHS terminal based on position information of a plurality of base stations. Patent Document 2 discloses a terminal device with a position information display function that can be used indoors or in a valley of a building by using a notification signal transmitted from each base station. In Patent Document 3, the center of gravity of a triangle having three base stations as vertices is obtained, a vector corresponding to the electric field strength is drawn from the centroid to each vertex, and the direction and position indicated by the vector composition are moving objects. A position detection method for calculating the current position of the terminal is disclosed.

JP 2001-333443 A JP 09-93653 A JP 2004-356755 A

  The electric field intensity of the radio wave emitted from the transmitting station varies depending on the surrounding environment such as shielding, crowds, and the direction of the measurer, as well as variations caused by the device itself, such as the installation position and power source. For this reason, if the current position is calculated using only the electric field strength, a large error is included in the calculated position. In other words, there is a certain correlation between the electric field strength and the distance, and as the electric field strength becomes weaker, the distance specified from the electric field strength includes a larger error. The error of the distance specified from the electric field strength becomes small. FIG. 13A is an example of an experimental result when the current position is calculated by sequentially selecting radio wave beacons from the received ones having the highest electric field strength. The calculated current position includes about 2 It can be seen that there are variations in the range of ~ 8 meters. In particular, in the navigation function that provides position information to a pedestrian who has a portable terminal or the like, the error included in the position information is too large and is inappropriate for the navigation function.

  Further, as shown in Patent Document 3, it is possible to calculate the current location from a triangle having three base stations as vertices. However, this method is not limited to the case where the mobile terminal is inside the triangle. You can calculate your current location even when you are outside.

  FIG. 18A shows the calculation of the current location when the mobile terminal held by the user is located outside the triangle in the triangle having the radio beacons (base stations) “Beacon5”, “Beacon6”, and “Beacon8” as vertices. An example is shown. In this example, the electric field strength of “Beacon6” is the highest, and the internal angle θ1 formed by “Beacon6” is less than 90 degrees. In such an example, the calculated current location P1 has a relatively small error and can be in the vicinity of the user U.

  On the other hand, as shown in FIG. 18B, when “Beacon3” and “Beacon8” are selected with “Beacon6” having the highest electric field strength as a base point, the internal angle θ2 of “Beacon6” becomes a very large angle. There is a case. For example, in the example shown in the figure, the internal angle θ2 indicates 120 degrees. In such an example, the calculated current location P2 may have a very large error, for example, larger than the error when the estimated distance is calculated from the reception intensity using a single radio beacon. May end up. FIG. 14A shows an experimental result of calculating the current location when the interior angle formed by the apex having the highest electric field strength is equal to or more than an obtuse angle. The calculated current location may include an error of about 20 meters. .

  The present invention solves such a conventional problem, and provides an electronic device, a position specifying program, and a position specifying method in which the current position specifying accuracy is improved by selecting a station by a method different from the conventional technique. For the purpose.

  An electronic apparatus according to the present invention includes a receiving unit that receives radio waves transmitted from each of at least three or more stations, a calculating unit that calculates reception intensity of each radio wave received by the receiving unit, and the calculating unit. First selection means for selecting a first station that transmits a radio wave having the strongest reception intensity among the calculated reception intensity, and a predetermined distance from the first station selected by the first selection means. A second selection means for selecting at least two stations, and a third selection for selecting the second station and the third station from the stations selected by the second selection means in descending order of reception intensity. And a determination means for determining whether or not the interior angle formed by the first station is an obtuse angle or more, the triangle having the first station, the second station, and the third station as vertices, and the determination If it is determined by the means that the angle is not obtuse, the first If the method determines the current location using the first station, the second station, and the third station, and if the determination means determines that the obtuse angle, the second station uses the first station, And specifying means for specifying the present location using the second station and the third station.

Preferably, the second method calculates the centroid of the triangle, and the first vector, the second vector, and the third vector from the calculated centroid to the first station, the second station, and the third station. Each of the vectors is weighted, and the current location is specified by combining the weighted first vector, second vector, and third vector. Preferably, the weighting is determined based on the first, second, and third reception strengths. Preferably, the weight is determined based on the first, second, and third estimated distances estimated from the first, second, and third received strengths. Preferably, in the second method, the current location is specified based on the following equation (1).

Preferably, the first method specifies the intersection of the first perpendicular to the straight line connecting the first station and the second station and the second perpendicular to the straight line connecting the first station and the third station as the current location. To do. Preferably, the position of the first perpendicular line and the position of the second perpendicular line are determined based on reception strengths of the first, second and third stations. Preferably, the position of the first perpendicular and the position of the second perpendicular are determined based on the first, second, and third estimated distances estimated from the first, second, and third received strengths. . Preferably, the determination unit calculates an internal angle formed by the first station based on the position information of the first, second, and third stations. Preferably, the determination means determines whether or not the internal angle formed by the first station is 120 degrees or more according to the equation (2).

  Preferably, the determination unit determines whether or not an internal angle formed by the first station is an obtuse angle or more based on a determination table prepared in advance.

  The position specifying program according to the present invention is executed by the control means of an electronic device including a receiving means for receiving radio waves and a control means for controlling position specification, and is received from each of a plurality of stations by the receiving means. When receiving the transmitted radio wave, a calculation step for calculating the reception intensity of each radio wave, and a first station for selecting the first station that transmits the radio wave having the strongest reception intensity among the reception intensity calculated by the calculation step Selected by the selection step, the second selection step of selecting at least two stations at a predetermined distance from the first station selected by the first selection step, and the second selection step. A third selection step of selecting a second station and a third station in order of increasing reception strength from the stations, and a triangle having the first station, the second station, and the third station as vertices. The second A determination step for determining whether or not an internal angle formed by the second station is equal to or greater than an obtuse angle, and when the determination step determines that the inner angle is not an obtuse angle, the first method, the second station, and the second If the current location is identified using the third station and the obtuse angle is determined by the determination step, the first station, the second station, and the third station are used by the second method. A first step of identifying a current location, wherein the first method includes: a first perpendicular to a straight line connecting the first station and the second station; and a first straight line connecting the first station and the third station. The intersection of two perpendiculars is identified as the current location, and the second method calculates the center of gravity of the triangle, and the first method is directed to the first station, the second station, and the third station from the calculated center of gravity. Weight each vector, second vector and third vector, Morning is first vector, identifying the current position by combining the second vector and the third vector.

  The position specifying method according to the present invention is in an electronic apparatus including a receiving means for receiving radio waves and a control means for controlling position specifying, and receives the radio waves transmitted from each of a plurality of stations by the receiving means. A calculation step for calculating the reception strength of each radio wave, a first selection step for selecting a first station that transmits a radio wave having the strongest reception strength among the reception strengths calculated by the calculation step, A second selection step for selecting at least two stations at a predetermined distance from the first station selected by the first selection step; and a reception strength among the stations selected by the second selection step. A third selection step of selecting the second station and the third station in order of increasing strength, and a triangle having the first station, the second station, and the third station as vertices, wherein the first station is The inner angle is obtuse A determination step for determining whether or not it is above, and if it is determined by the determination step that the angle is not obtuse, using the first station, the second station, and the third station by the first method A specifying step of specifying the current location and specifying the current location using the first station, the second station, and the third station by the second method when the determination step determines that the angle is obtuse by the determination step; The first method includes the intersection of the first perpendicular to the straight line connecting the first station and the second station and the second perpendicular to the straight line connecting the first station and the third station. And the second method calculates a centroid of the triangle, a first vector from the calculated centroid to a first station, a second station, and a third station, a second vector, and Weight each third vector and weighted first vector , To identify the current position by combining the second vector and the third vector.

  According to the present invention, it is determined whether or not an interior angle formed by the first station is an obtuse angle or more with a triangle having the selected first, second and third stations as vertices, and based on the determination result Since the current location is specified by the first method or the second method, even if the electronic device is located outside the triangle, it is possible to specify the current location with less error compared to the conventional method. In particular, when one vertex of the triangle has an obtuse angle of 90 degrees or more, the position accuracy of the current location can be improved.

It is a block diagram which shows the structural example of the information terminal which concerns on the Example of this invention. It is a figure which illustrates the list of the base stations which the communication part of the information terminal which concerns on the Example of this invention receives. It is a figure which shows the memory | storage system of beacon information. It is a figure which shows the functional structural example of the position specification program which concerns on 1st Example of this invention. It is a figure which shows the relationship between the electric field strength regarding distance estimation of a distance estimation part, and distance. It is a figure which illustrates typically the angle determination of the internal angle determination part which concerns on a 1st Example. It is a figure which illustrates typically the calculation of the gravity center by the gravity center calculation part which concerns on a 1st Example. It is a figure which illustrates typically the present location specification of the 2nd present location specific part which concerns on a 1st Example. It is a flow which shows the position specific operation | movement which concerns on a 1st Example. It is a figure which shows the specific selection example of the 1st station selection part which concerns on a 1st Example, a near station selection part, and a 2nd / 3rd station selection part. FIG. 11A is a conceptual diagram showing a positional relationship between a user holding an information terminal and each beacon. FIG. 11B is an overhead view of the bird's eye view of the XY plane shown in FIG. FIG. 12A is a conceptual diagram showing a positional relationship between a user holding an information terminal and each beacon. FIG. 12B is an overhead view of the bird's eye view of the XY plane shown in FIG. FIG. 13A shows the experimental result of error RMS in the conventional position specification, and FIG. 13B shows the experimental result of error RMS in the position specification of the present embodiment. It is a figure explaining the effect at the time of switching the 1st present location specific part or the 2nd present location specific part based on the judgment result of an interior angle judging part. It is a figure which shows the functional structural example of the position specific program which concerns on 2nd Example of this invention. It is a figure which shows an example of the adjacency determination table used for a 2nd Example. It is a flow which shows the position specific operation | movement which concerns on a 2nd Example. It is a figure which illustrates typically an error at the time of performing position calculation using three conventional base stations.

  The electronic device of the present invention can be a portable information terminal such as a smartphone, a mobile phone, or a tablet terminal, or a navigation device. The information terminal preferably has a navigation function, a function of communicating with an in-vehicle device or a server. For example, when such an information terminal is brought into the vehicle, the information terminal is connected to an electronic device in the vehicle, and the electronic device can use a function installed in the information terminal. For example, an electronic device in a vehicle can use its own navigation function or the navigation function of an information terminal.

  FIG. 1 is a block diagram showing a configuration example of an information terminal according to the first embodiment of the present invention. The information terminal 10 according to the present embodiment includes an input unit 100, a communication unit 110, a display unit 120, an audio output unit 130, a storage unit 140, and a control unit 150. However, the structure shown here is an example, and the present invention is not limited to this.

  The input unit 100 receives an input from the user and provides it to the control unit 150. The communication unit 110 transmits and receives data to and from various devices and devices via wireless or wired communication. Further, the communication unit 110 according to the present embodiment receives radio waves from a base station (hereinafter sometimes referred to as a beacon) that transmits radio waves including at least identification information (ID) of the local station from a predetermined installation position. It has the function to do. The communication unit 110 receives radio waves emitted from each of the plurality of base stations when there are a plurality of base stations around the information terminal. At that time, the communication unit 110 extracts the identification information included in the radio wave and holds the reception intensity. FIG. 2 is an illustration of a reception situation when the communication unit 110 receives radio waves from a plurality of base stations. As shown in the figure, a receiving base station receiving a radio wave (here, Beacon 1 to Beacon 8 is illustrated) and an RSSI (Received Signal Strength Indicator) representing each radio wave intensity (dB) are shown. For example, the base station with the highest reception strength is “Beacon 6”. Information regarding the radio waves at the time of reception is provided to the storage unit 140 and the control unit 150.

  The display unit 120 is a display device such as a liquid crystal display. The audio output unit 130 outputs audio data generated by an application executed by the information terminal 10. The storage unit 140 can store application software executed by the information terminal 10, a program executed by the control unit 150, and other necessary data. In addition, the storage unit 140 stores information on radio waves received by the communication unit 110 as shown in FIG. 2 and updates the information every time the reception environment changes.

  The storage unit 140 can further store location information of the base station. For example, as illustrated in FIG. 3, the storage unit 140 stores base station information indicating the relationship between base station identification information, beacon names, and position information. The radio wave transmitted from each base station includes its own identification information (ID). By referring to the base station information in FIG. 3, the beacon name is identified from the identification information, and the position information is Can be acquired. For example, when the identification information “CCC” encoded in the radio wave received by the communication unit 110 is included, “Beacon3” is identified by decoding the identification information, and the corresponding position information (X3, Y3) can be acquired. The position information may be information indicating latitude and longitude, for example, or other information that can specify the beacon position. Further, with respect to the information regarding the radio wave at the time of reception shown in FIG.

  In another aspect, the base station information as shown in FIG. 3 can be acquired from the outside. For example, a server that distributes base station information may be accessed via the communication unit 110, necessary base station information may be acquired from the server, and stored in the storage unit 140.

  In a preferred embodiment, the control unit 150 includes a microcontroller including a ROM, a RAM, and the like, and the ROM or the RAM can store various programs for controlling the operation of each unit of the information terminal 10. In this embodiment, a position specifying program 200 for specifying the position of the information terminal 10 is included.

  FIG. 4 is a diagram illustrating a functional configuration example of the position specifying program 200. The position specifying program 200 includes a reception intensity calculation unit 210, a first station selection unit 220, a proximity station selection unit 230, a second / third station selection unit 240, a distance estimation unit 250, an interior angle determination unit 260, a center of gravity calculation unit 270, A first current location specifying unit 280 and a second current location specifying unit 290 are included. The position specifying program 200 of the present embodiment uses a triangle having the three selected beacons as apexes to specify the current location. If the inner angle of the beacon with the highest electric field strength is less than an obtuse angle (acute angle), the first is specified. The current location is specified by the current location specifying unit 280, and if the cabinet is an obtuse angle or more, the current location is specified by the second current location specifying unit 290. Further, the location specifying program 200 of the present embodiment applies the logic for specifying the current location regardless of whether the position of the information terminal 10 is inside or outside the triangle.

  The reception strength calculation unit 210 calculates the reception strength (electric field strength) of the received radio wave received by the communication unit 110. The first station selection unit 220 may be referred to as a base station (hereinafter, referred to as a first base station or a first beacon) that transmits a radio wave having the highest electric field strength among the electric field strengths calculated by the reception strength calculation unit 210. ) Is selected. Proximity station selection section 230 selects a base station that is close to the first base station selected by first station selection section 220 from the received radio waves of each base station received by communication section 110. Preferably, based on the base station information shown in FIG. 3, a base station that is within a predetermined distance (range) from the position information of the first base station selected by the first station selecting unit 220 Select as station. Preferably, the neighboring station selection unit 230 extracts at least two or more neighboring base stations.

  The second / third station selecting unit 240 includes two beacons (hereinafter referred to as the second base station or the second beacon and the third base station) in order of increasing electric field strength from the base stations selected by the neighboring station selecting unit 230. Or may be referred to as a third beacon). The second base station transmits a radio wave having a stronger electric field strength than the third base station.

  The distance estimation unit 250 estimates the distance from the electric field strength of radio waves received by the first to third base stations. This distance is used in a first current location specifying unit 280 and a second current location specifying unit 290 described later. A certain correlation is estimated between the radio wave reception intensity (electric field intensity) and the distance. FIG. 5 is a graph showing the correlation between the electric field strength and the distance, and the correlation between the electric field strength and the distance can be approximated by a straight line f. If the electric field strength is high, it is possible to specify a more accurate distance from the electric field strength. Conversely, if the electric field strength is low, the distance specified from the electric field strength includes a large error. For example, if the electric field strength is about -70 dB, even if the distance is calculated from the electric field strength, the distance includes a large error (estimation error). The straight line f is calculated by, for example, measuring how much the reception sensitivity (electric field strength) changes when the distance changes, and obtaining a straight line f or an approximate expression from such a plurality of measured values by a statistical method. be able to. The distance estimation unit 250 uses such a straight line f to provide a first distance corresponding to the electric field strength of the first base station, a second distance corresponding to the electric field strength of the second base station, and a third base station. A third distance corresponding to the electric field strength is estimated. In addition to the correlation of the straight line f, the distance may be estimated from a mathematical expression or a table indicating another correlation.

When the first base station, the second base station, and the third base station are selected, the interior angle determination unit 260 is a triangle whose apex is the position of these base stations, and the interior angle formed by the first base station is determined in advance. It is determined whether the angle is equal to or greater than a predetermined angle, that is, an obtuse angle (90 degrees). The position information of each base station can be obtained from the base station information shown in FIG. 3, for example. As shown in FIG. 6, when the first base station is point A, the second base station is point B, and the third base station is point C, the interior angle determination unit 260 has a straight line connecting point A and point B, It is determined whether or not the internal angle θ _A formed by the straight line connecting the point A and the point C is an obtuse angle or more. When the interior angle of the first base station A becomes an obtuse angle, as shown in FIG. 14A, the error included in the identified current location can be significantly increased. In the following description, as an example, it is assumed that the obtuse angle is 120 degrees, and the interior angle determination unit 260 determines whether the interior angle of the first base station is 120 degrees or more.

ここで、ベクトルａ、図６に示す第１基地局（点Ａ）を始点、第２基地局（点Ｂ）を終点としたベクトルを示し、ベクトルｂは、第１基地局（点Ａ）を始点、第３基地局（点Ｃ）を終点としたベクトルを示している。もし、鈍角が９０度とする場合には、「cosπ／２」である。 In a preferred embodiment, the interior angle determination unit 260 can determine whether or not the interior angle θ _A is greater than 120 degrees using the following inequality.

Here, vector a indicates a vector having the first base station (point A) shown in FIG. 6 as the start point and the second base station (point B) as the end point, and vector b indicates the first base station (point A). A vector having a start point and a third base station (point C) as an end point is shown. If the obtuse angle is 90 degrees, it is “cosπ / 2”.

  The center-of-gravity calculation unit 270 calculates the center of gravity of the triangle formed based on the positions of the first base station, the second base station, and the third base station. FIG. 7 is a diagram for schematically explaining the calculation of the center of gravity point by the center of gravity calculation unit 270. As shown in the figure, point A is a first base station, point B is a second base station, point C is a third base station, and a vector from any origin O to points A, B, and C is a vector. In the case of A, vector B, and vector C, the vector G from the origin O toward the center of gravity G can be calculated by 1/3 of the synthesis of the vectors A, B, and C (see FIG. 7A). ). When the coordinates of the point A are (x1, y1), the coordinates of the point B are (x2, y2), and the coordinates of the point C are (x3, y3), the coordinates of the center of gravity G are as shown in FIG. It can be calculated by the formula shown. Furthermore, as shown in FIG. 7C, the center of gravity G may be calculated from the intersection of straight lines from each vertex toward the midpoint of the opposite side. The calculation method of the center of gravity is not limited to the method illustrated in FIG. 7 and can be calculated by a known mathematical method.

  The first current location specifying unit 280 uses the first to third base station position information and the first to third base stations estimated by the distance estimation unit 250 when the inner angle formed by the first reference station is less than an obtuse angle by the inner angle determination unit 260. Based on the third distance, the current location of the information terminal 10 is specified. The first current location specifying unit 280 is a perpendicular to the straight line (hereinafter sometimes referred to as the first straight line) connecting the first base station and the second base station (hereinafter may be referred to as the first perpendicular), An intersection point of a perpendicular (hereinafter also referred to as a second perpendicular) with respect to a straight line (hereinafter sometimes referred to as a second straight line) connecting the first base station and the third base station is specified as the current location. Preferably, the position of the first perpendicular is determined by the ratio of the first distance and the second distance, and the position of the second perpendicular is determined by the ratio of the first distance and the third distance. Details will be described later with a specific example (see FIG. 11B).

  The second current location specifying unit 290 specifies the current location of the information terminal 10 using the center of gravity calculated by the center of gravity calculating unit 270 when the inner angle formed by the first reference station is equal to or greater than the obtuse angle by the inner angle determining unit 260. Preferably, the second current location specifying unit 290 weights the center of gravity by the first to third distances estimated by the distance estimating unit 250, and specifies the weighted center of gravity as the current location.

ここで、ｄ_Ａは距離推定部２５０によって推定された第１の距離、ｄ_Ｂは距離推定部２５０によって推定された第２の距離、ｄ_Ｃは距離推定部２５０によって推定された第３の距離、Ｐ_Ａベクトルは重心算出部２７０によって算出された重心Ｇを始点とし、第１基地局（点Ａ）を終点とするベクトル、Ｐ_Ｂベクトルは重心Ｇを始点とし、第２基地局（点Ｂ）を終点とするベクトル、Ｐ_Ｃベクトルは重心Ｇを始点とし、第３基地局（点Ｃ）を終点とするベクトル、Ｐ_０ベクトルは重心Ｇを始点とし、重み付けされた重心（すなわち現在地）を終点とするベクトルを示している（図８参照）。 Specifically, the second current location specifying unit 290 specifies the current location of the information terminal 10 using the following equation.

Here, d _A is the first distance estimated by the distance estimation unit 250, d _B is the second distance estimated by the distance estimation unit 250, and d _C is the third distance estimated by the distance estimation unit 250. , P _a vector is starting from the center of gravity G calculated by the centroid calculating unit 270, a vector in which the first base station (point a) and ending, P _B vector is starting from the center of gravity G, the second base station (point B ) and an end point vector, P _C vector is starting from the center of gravity G, vectors third base station (point C) and the end point, P ₀ vector is starting from the center of gravity G, weighted centroids (i.e. the current position) A vector as an end point is shown (see FIG. 8).

  Thus, the second method estimates the center of gravity Po to the current location by weighting the estimated distance based on the electric field strength to each vector, so that the estimated current location is attracted to the first base station side, As a result, the internal angle of the first base station is an obtuse angle, and it is possible to suppress the deterioration of the position accuracy when the information terminal 10 is located outside the triangle.

  Next, the operation of this embodiment will be described. FIG. 9 is an operation flow of the position specifying program 200 of this embodiment. The position specifying program 200 is activated, for example, when the navigation function of the information terminal 10 is executed. First, radio waves emitted from a plurality of base stations are received by the communication unit 110 of the information terminal 10. Then, the field strength of each received radio wave received by the communication unit 110 is calculated by the reception strength calculation unit 210 (S100), and the first field selection unit 220 has the highest field strength among the field strengths calculated in S100. A first beacon (first base station) that transmits a strong radio wave is selected (S102). When the first beacon is selected, the close station selection unit 230 selects at least two beacons that are close to the first beacon based on the base station information (FIG. 3) stored in the storage unit 140. (S104). Next, the second / third station selecting unit 240 selects, as the second beacon, a beacon that transmits a radio wave having the strongest electric field strength from the neighboring beacons selected by the neighboring station selecting unit 230, and the second electric field A beacon that transmits a strong radio wave is selected as the third beacon (S106). Next, the distance estimation unit 250 estimates the first distance, the second distance, and the third distance corresponding to the electric field strength based on the straight line f shown in FIG. 5 (S108).

  Next, the interior angle determination unit 260 determines whether the interior angle formed by the first, second, and third beacons is an obtuse angle (S110). When it is determined that the interior angle is less than the obtuse angle, the first current location specifying unit 280 determines the position of the first perpendicular based on the first distance and the second distance (S112), and the first distance and the third distance The position of the second perpendicular is determined based on the distance (S114), and the intersection of the first perpendicular and the second perpendicular is specified as the current location (S116). On the other hand, if it is determined that the interior angle is equal to or greater than the obtuse angle, the center-of-gravity calculation unit 270 calculates the center of gravity of the triangles of the first, second, and third beacons (S118), and then the second current location specifying unit 290 calculates The weighted center of gravity is weighted by the first to third distances estimated by the distance estimating unit 250, and the current location is identified from the weighted center of gravity (S120).

  The current position thus identified is used, for example, for displaying the current position of the navigation function of the information terminal 10 and for route guidance. Alternatively, when the information terminal 10 is connected to the in-vehicle device, it is used for the navigation function of the in-vehicle device.

  Next, a specific example of estimating the current location will be described. FIG. 10 is a diagram illustrating a specific selection example of the first station selection unit 220, the adjacent station selection unit 230, and the second / third station selection unit 240. As shown in FIG. 10A, the first station selection unit 220 uses a beacon that transmits a radio wave having the strongest electric field strength among the electric field strengths calculated by the reception strength calculation unit 210, that is, Beacon6 as the first beacon. Select (equivalent to S102). As shown in FIG. 10 (B), the close station selection unit 230 determines a predetermined distance (range) from the Beacon 6 based on the position information of the base station information (see FIG. 3) stored in the storage unit 140. Select a beacon within. In this embodiment, Beacon3, Beacon4, Beacon5, Beacon7, and Beacon8 are selected as adjacent beacons (corresponding to S104). The second / third station selection unit 240 selects Beacon3, which is a beacon that transmits the strongest electric field intensity, among Beacon3, Beacon4, Beacon5, Beacon7, and Beacon8, and transmits the second strongest electric field intensity. Beacon4 that is a beacon to be selected is selected as the third beacon (corresponding to S106). In this embodiment, as shown in the specific example of FIG. 10, even if there are Beacon1 and Beacon2 having the next highest electric field strength after the first beacon, if they are not close to the first beacon, Not selected or used. This is because the beacon that is closer to the first beacon is expected to be in the same radio wave environment as the first beacon, and the beacon that is far from the first beacon has the effect of multipath and interference. This is because it is expected that they may have received it.

FIG. 11A is a conceptual diagram showing a positional relationship between the user U holding the information terminal 10 and each beacon. FIG. 11A shows the user U walking on the XY plane. FIG. 11B is an overhead view of the bird's eye view of the XY plane shown in FIG. As shown in FIG. 11B, the first beacon Beacon 6 is a beacon having information that the electric field intensity is −65 dBm and the estimated distance is 2.56 m, and the second beacon Beacon 3 is an electric field intensity of −68 dBm. The beacon 4 having the information of distance 2.66 m and the third beacon 4 is a beacon having information of the electric field strength of −69 dBm and the estimated distance of 2.67 m. Each estimated distance is estimated by the distance estimation unit 250. Further, the internal angle θ _A determined by the internal angle determination unit 260 is less than an obtuse angle, and therefore the position is specified by the first position current location specifying unit 280. The first current location specifying unit 280 first determines a first perpendicular L2 with respect to the first straight line L1 of the first and second beacons. That is, the position of the first perpendicular line L2 is determined by the ratio “a: b” that is equal to the ratio “2.56: 2.66” of the first distance and the second distance. Similarly, the position of the second perpendicular L4 to the second straight line L3 of the first and third beacons is equal to the ratio of the first distance to the third distance “2.56: 2.67”. c: d "ratio. In this way, the first current location specifying unit 280 specifies the intersection of the first perpendicular L2 and the second perpendicular L4 as the current location P.

Next, a specific example of specifying the current location by the second current location specifying unit 290 will be described. FIG. 12A is a conceptual diagram showing a positional relationship between a user holding an information terminal and each beacon, and FIG. 12B is an overhead view overlooking the XY plane shown in FIG. . Here, Beacon6 is selected as the first beacon, Beacon4 is selected as the second beacon, Beacon7 is selected as the third beacon, and the inner angle θ _A formed by the first beacon (Beacon6) having the highest electric field strength in the triangle formed by these beacons. Is an obtuse angle or more. Thus, the second current location specifying unit 290 specifies the current location Po by weighting the center of gravity of the triangle with the first to third distances.

  FIG. 13 (A) shows experimental results of error RMS (Root Mean Square) when the current position is specified by sequentially selecting the ones with high electric field strength according to the conventional method, and FIG. 13 (B) shows the present embodiment. The experimental result of the error RMS of the current position specified by the example is shown. However, the experimental result in FIG. 13B is a result when the current location is uniformly specified by the first current location specifying unit 280 without performing the internal angle determination of the triangle shown in S110 of FIG. In the conventional method, the error varies and the error range is large. On the other hand, the position specifying method of this embodiment has a small error variation and a small error range, and the error is small. It can be seen that the position can be identified stably.

  Next, the effects when the current location is specified using only the first current location specifying portion and when the first current location specifying portion and the second current location specifying portion are used in combination will be described. FIG. 14A shows the error of the current location specified by the first current location specifying unit 280 when the angle determination of the interior angle of the triangle is not performed, and the average error is 13.1 m. FIG. 14B shows the error of the current location when the angle of the interior angle of the triangle is determined and the first current location specifying unit 280 and the second current location specifying unit 290 are selectively switched, and the average error is 8 .6 m. Thus, it turns out that an error is reduced by switching the 1st present location specific part or the 2nd present location specific part according to the interior angle of a triangle.

  In the above-described embodiment, an example in which a neighboring base station is selected based on the base station information stored in the storage unit 140 has been described. When the position information to be expressed is included, the position information may be extracted from the radio wave, and the adjacent station selection unit 230 may select the adjacent base station using the extracted position information.

  Next, a second embodiment of the present invention will be described. In the first example, the current location specifying method by the first current location specifying unit 280 or the second current location specifying unit 290 is switched based on the determination result of the interior angle determination unit 260. However, in the second example, the electric field strength is changed. The current location specifying method of the first current location specifying unit 280 or the second current location specifying unit 290 is switched using the adjacency determination table without determining whether or not the interior angle formed by the first base station having the highest is more than an obtuse angle. Is.

  FIG. 15 is a diagram showing a functional configuration example of the position specifying program 200A according to the second embodiment of the present invention. The position specifying program 200A according to the second embodiment has an adjacent determination section 260A instead of the interior angle determination section 260 in the first embodiment, and other configurations are the same as those in the first embodiment. The explanation is omitted because it is the same.

  The adjacency determination unit 260A determines whether or not the second base station and the third base station selected by the second / third station selection unit 240 are adjacent to each other. Preferably, an adjacency determination table prepared in advance is used. Use and judge. Whether or not the second base station and the third base station are adjacent to each other corresponds to the determination as to whether or not the interior angle in the first embodiment is an obtuse angle. The second base station and the third base station Are adjacent to each other, the internal angle formed by the first base station is considered to be less than an obtuse angle (acute angle), and if not adjacent to each other, the internal angle formed by the first base station is considered to be greater than or equal to the obtuse angle. Is equivalent to that. Accordingly, when the adjacency determination unit 260A determines that the second base station and the third base station are adjacent, the current location is specified by the first current location specifying unit 280 and is determined not to be adjacent. If the current location is determined, the current location is specified by the second current location specifying unit 290.

  The determination by the adjacent determination unit 260A refers to the adjacent determination table stored in the storage unit 140. FIG. 16A is a diagram illustrating an example of the adjacency determination table. The adjacency determination table defines the relationship between the first base station and the second and third base stations that can satisfy the adjacency relationship. For example, it is assumed that beacons are arranged as shown in FIG. When Beacon4 is selected as the first base station, the base stations satisfying the adjacency relationship are Beacon1,2,3,5,6. If the second base station and the third base station are any of Beacon 1, 2, 3, 5, 6, it is determined that the second base station and the third base station are adjacent to each other. If any of the three base stations corresponds to Beacon 7 or 8, it is determined that they are not adjacent. For example, in FIG. 16B, when Beacon6 is selected as the first base station, Beacon4 is selected as the second base station, and Beacon7 is selected as the third base station, Beacon7 is not included in the base stations that satisfy the adjacency condition. Therefore, the adjacency determination unit 260A determines that the second base station and the third base station are not adjacent. In other words, if all of the selected three base stations are included in one row of the adjacency determination table, it is determined as “adjacent”; otherwise, it is determined as “not adjacent”. Is done. In the above example, since there is no row including all of Beacon 4, 6, and 7, it is determined as “not adjacent”.

  FIG. 17 is a diagram illustrating an operation flow of the position specifying program 200 according to the second embodiment. Compared with the operation flow shown in FIG. 9 according to the first embodiment, the operation flow of the position specifying program 200 according to the second embodiment is determined by the interior angle determination unit 260 (S110) and the adjacent determination unit 260A. (S111), and the other steps are the same.

  As described above, according to the second embodiment, by using the adjacent determination hand table, it is possible to simplify the determination as to whether or not the interior angle formed by the first base station is equal to or greater than the obtuse angle as in the first embodiment. The present location can be identified efficiently and in a short time.

  Next, a modification of the first embodiment or the second embodiment will be described. The proximity station selection unit 230 in the first embodiment or the second embodiment approaches a base station within a predetermined range from the position information of the first base station based on the base station information shown in FIG. Although the base station is selected, the close station selection unit 230 may select the close station based on a table as shown in FIG. That is, a table in which beacons that are close to each beacon are associated is stored in advance in the storage unit 140, and a beacon associated with the first beacon selected by the first station selection unit 220 is selected as a proximity beacon. be able to.

  The preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to the specific embodiment, and various modifications and variations are possible within the scope of the gist of the invention described in the claims. It can be changed.

10: information terminal 100: input unit 110: communication unit 120: display unit 130: audio output unit 140: storage unit 150: control unit 200: position specifying program 210: reception intensity calculation unit 220: first station selection unit 230: proximity Station selection unit 240: Second / third station selection unit 250: Distance estimation unit 260: Interior angle determination unit 260A: Adjacent determination unit 270: Center of gravity calculation unit 280: First current location specifying unit 290: Second current location specifying unit G: Center of gravity f: Straight line L1: First straight line L2: First perpendicular line L3: Second straight line L4: Second perpendicular lines P, P1, P2: Current location U: User

Claims (13)

Receiving means for receiving radio waves transmitted from each of at least three or more stations;
Calculating means for calculating the reception intensity of each radio wave received by the receiving means;
First selection means for selecting a first station that transmits a radio wave having the strongest reception strength among the reception strengths calculated by the calculation means;
Second selection means for selecting at least two stations at a predetermined distance from the first station selected by the first selection means;
Third selection means for selecting the second station and the third station from the stations selected by the second selection means in descending order of reception intensity;
Determining means for determining whether or not the interior angle formed by the first station is an obtuse angle or more, which is a triangle having the first station, the second station, and the third station as vertices;
When it is determined that the angle is not obtuse by the determination means, the current location is identified using the first station, the second station, and the third station by the first method, and the obtuse angle is determined by the determination means. If determined, a specifying means for specifying the present location using the first station, the second station, and the third station by the second method;
An electronic device. The second method calculates a centroid of the triangle, and a first vector, a second vector, and a third vector directed from the calculated centroid to a first station, a second station, and a third station. The electronic device according to claim 1, wherein each of the electronic devices is weighted, and the current location is specified by combining the weighted first vector, the second vector, and the third vector. The electronic device according to claim 2, wherein the weighting is determined based on first, second, and third reception strengths. The electronic device according to claim 2, wherein the weighting is determined based on first, second, and third estimated distances estimated from first, second, and third reception strengths. The electronic device according to claim 4, wherein the second method specifies a current location based on the following expression (1).

The first method specifies, as a current location, an intersection of a first perpendicular to a straight line connecting the first station and the second station and a second perpendicular to the straight line connecting the first station and the third station. The electronic device according to claim 1. The electronic device according to claim 6, wherein a position of the first perpendicular and a position of the second perpendicular are determined based on reception strengths of the first, second, and third stations. The position of the first perpendicular and the position of the second perpendicular are determined based on first, second, and third estimated distances estimated from the first, second, and third received strengths. Item 7. The electronic device according to Item 6. The electronic device according to claim 1, wherein the determination unit calculates an internal angle formed by the first station based on position information of the first, second, and third stations. 2. The electronic device according to claim 1, wherein the determination unit determines whether or not an internal angle formed by the first station is 120 degrees or more according to the equation (2).

The electronic device according to claim 1, wherein the determination unit determines whether the internal angle formed by the first station is equal to or greater than an obtuse angle based on a determination table prepared in advance. A position specifying program executed by the control means of the electronic device including a receiving means for receiving radio waves and a control means for controlling position specifying,
A calculation step of calculating reception intensity of each radio wave when receiving radio waves transmitted from each of a plurality of stations by the receiving means;
A first selection step of selecting a first station that transmits a radio wave having the strongest reception strength among the reception strengths calculated in the calculation step;
A second selection step of selecting at least two stations at a predetermined distance from the first station selected by the first selection step;
A third selection step of selecting the second station and the third station from the stations selected in the second selection step in descending order of reception intensity;
A determination step of determining whether the first station, the second station, and the third station are triangles having apexes, and the interior angle formed by the first station is equal to or greater than an obtuse angle;
If it is determined that the angle is not obtuse by the determination step, the current location is specified using the first station, the second station, and the third station by the first method, and the obtuse angle is determined by the determination step. If determined, using the second method to identify the current location using the first station, the second station and the third station, and
The first method specifies, as a current location, an intersection of a first perpendicular to a straight line connecting the first station and the second station and a second perpendicular to the straight line connecting the first station and the third station;
The second method calculates a centroid of the triangle, and a first vector, a second vector, and a third vector directed from the calculated centroid to a first station, a second station, and a third station. A position specifying program that weights each of the current position and specifies the current location by combining the weighted first vector, second vector, and third vector. A position specifying method in an electronic device including a receiving means for receiving radio waves and a control means for controlling position specifying,
A calculation step of calculating reception intensity of each radio wave when receiving radio waves transmitted from each of a plurality of stations by the receiving means;
A first selection step of selecting a first station that transmits a radio wave having the strongest reception strength among the reception strengths calculated in the calculation step;
A second selection step of selecting at least two stations at a predetermined distance from the first station selected by the first selection step;
A third selection step of selecting the second station and the third station from the stations selected in the second selection step in descending order of reception intensity;
A determination step of determining whether the first station, the second station, and the third station are triangles having apexes, and the interior angle formed by the first station is equal to or greater than an obtuse angle;
If it is determined that the angle is not obtuse by the determination step, the current location is specified using the first station, the second station, and the third station by the first method, and the obtuse angle is determined by the determination step. If determined, using the second method to identify the current location using the first station, the second station and the third station, and
The first method specifies, as a current location, an intersection of a first perpendicular to a straight line connecting the first station and the second station and a second perpendicular to the straight line connecting the first station and the third station;
The second method calculates a centroid of the triangle, and a first vector, a second vector, and a third vector directed from the calculated centroid to a first station, a second station, and a third station. A position specifying method in which the current location is specified by combining the weighted first vector, the second vector, and the third vector.

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