JP2020122742A - Positioning device - Google Patents

Abstract

To accurately determine a position of a wireless terminal.SOLUTION: An information processor 20 executes: information acquisition processing for acquiring, from a wireless terminal 12, a distance measurement value between each of three stationary stations 14-1 to 14-3 and the wireless terminal 12; distance correction processing for sequentially executing correction on two distance measurement values out of three distance measurement values, for three combinations which select two of the three distance measurement values; and position determination processing for determining the position of the wireless terminal 12 on the basis of the three distance measurement values after the distance correction processing has been executed. The distance correction processing includes geometrical correction processing which determines a geometrical relation between two circles that are respectively centered at positions of two stationary stations for which two distance measurement values have been determined and that have the two distance measurement values as their radii, and corrects the two distance measurement values on the basis of the determination result.SELECTED DRAWING: Figure 1

Description

The present invention relates to a positioning device, and more particularly to a positioning device that measures the position of a wireless terminal based on the distance between the wireless terminal and each of a plurality of fixed stations.

Research and development are being conducted on positioning systems that measure the position of wireless terminals. The wireless terminal measures the distance to each fixed station by transmitting and receiving wireless signals to and from a plurality of fixed stations whose positions are known. The information processing apparatus acquires the distance measurement result from the wireless terminal and obtains the position of the wireless terminal based on the distance from the wireless terminal to each fixed station. Such a positioning system is expected to be applied to confirmation of a person's whereabouts in a building and inventory control in a factory.

As a positioning system, the following patent document 1 describes a system that searches for the position of a moving body that holds a beacon device. In this system, each of the plurality of mobile terminals receives the beacon signal transmitted from the beacon device and obtains the distance to the beacon device. The mobile search server acquires the position of each mobile terminal and the information indicating the distance to the beacon device from each mobile terminal, and obtains the position of the beacon device.

In addition, Patent Document 2 describes a wireless tag distance measuring device. The wireless tag distance measuring device transmits a distance measurement signal to the wireless tag and receives an incoming signal transmitted from the wireless tag in response thereto. The wireless tag distance measuring device measures the distance from the wireless tag distance measuring device to the wireless tag based on the time from transmitting the distance measuring signal to receiving the incoming signal. This document describes that the position of a wireless tag is obtained based on distance measurement results obtained by a plurality of wireless tag distance measuring devices.

Non-Patent Document 1 discloses a technique for obtaining the distance between a measurement target node whose position is unknown and each of three reference nodes whose positions are known, and for obtaining the position of the measurement target by a three-point positioning method. Have been described. In the three-point positioning method, a circle whose center is the position of the reference node and whose radius is the distance to the reference node is obtained for each of the three reference nodes, and the intersection of the three circles is obtained as the position of the measurement target node. Is the way.

JP, 2016-218931, A JP, 2009-174971, A

A Novel Enhance Positioning Trilateration Algorithm Implementation for Medical Implant In-Body Localization, International Journal of Antennas and Propagation, Vol 2013, Article ID 819695

In a system for positioning a wireless terminal, the wireless terminal is positioned using a wireless signal. Therefore, the positioning accuracy may not be sufficient depending on the radio signal propagation situation.

An object of the present invention is to obtain the position of a wireless terminal with high accuracy.

The present invention provides an information acquisition process of acquiring a distance measurement value between each of three fixed stations and a wireless terminal from at least one of the three fixed stations or the wireless terminal, and three distances. A distance correction process of sequentially performing correction on two distance measurement values out of the three measured values for three combinations of selecting two from the three distance measurement values, and the three after the distance correction process is performed. Position determination processing for determining the position of the wireless terminal based on one distance measurement value, and the distance correction processing determines the position of each of the two fixed stations for which the two distance measurement values are determined. A geometry for determining the geometric relationship of two circles having the center as the center and having the two distance measurement values as their respective radii, and correcting the two distance measurement values based on the determination result of the geometric relationship. It is characterized by including a geometric correction process.

Desirably, the geometric correction processing is performed on a determination result of the geometrical relationship, the two distance measurement values, and a distance between the two fixed stations from which the two distance measurement values are obtained. Based on the above, a process of correcting the two distance measurement values is included.

Desirably, the geometric correction process is such that a circle centered on one of the two fixed stations and having a radius of a distance measured value corresponding to one of the two fixed stations. The center of the other position of the two fixed stations, and the circle having the radius of the distance measurement value corresponding to the other fixed station of the two distance measurement values is in contact with at one point. It is characterized by including a process of correcting one distance measurement value.

According to the present invention, the position of a wireless terminal can be obtained with high accuracy.

It is a figure which shows the positioning system which concerns on 1st Embodiment. It is a figure which shows the circle C _i and the circle C _j which have a two-point crossing relationship. It is a figure which shows the circle C _i and the circle C _j which have a C _i C _j inclusion relation. It is a figure which shows the circle C _i and the circle C _j which have a C _j C _i inclusive relation. It is a figure which shows the circle C _i and the circle C _j which have an isolation relationship. It is a figure which shows the circle C _i and the circle C _j which have a one-point contact relationship. By the distance correction process is a diagram illustrating a circle C ₁ -C ₃ in which a state of intersecting at one point. It is a figure which shows the example of the hardware of a wireless terminal. It is a figure which shows the example of the hardware of an information processing apparatus. It is a figure which shows the positioning system which concerns on 2nd Embodiment.

(1) Overview of Positioning System FIG. 1 shows a positioning system 10 according to an embodiment of the present invention. The positioning system 10 includes a wireless terminal 12, fixed stations 14-1 to 14-3, a network wireless device 16, a communication line 18, and an information processing device 20.

The wireless terminal 12 transmits and receives wireless signals to and from each of the fixed stations 14-1 to 14-3, and measures the distance to each fixed station. The network wireless device 16 performs wireless communication with the wireless terminal 12 and acquires measurement information indicating the measurement result by the wireless terminal 12. The network wireless device 16 transmits the measurement information acquired from the wireless terminal 12 to the information processing device 20 via the communication line 18 such as the Internet. The information processing device 20 as a positioning device corrects each distance measurement value included in the measurement information by a distance correction process described later, and measures the position of the wireless terminal 12 based on each corrected distance measurement value.

(2) Positioning Process Executed by Positioning System (2-1) Overview of Positioning Process The process executed by the positioning system 10 according to the present embodiment will be specifically described. The wireless terminal 12 transmits and receives wireless signals to and from each of the fixed stations 14-1 to 14-3, measures the distance to each fixed station, and acquires each distance measurement value. The wireless terminal 12 generates measurement information including the distance measurement values r _{1 to} r ₃ . However, the distance measurement values r _{1 to} r ₃ are measurement values of the distance from the wireless terminal 12 to the fixed stations 14-1 to 14-3, respectively. The wireless terminal 12 performs wireless communication with the network wireless device 16 and transmits measurement information to the network wireless device 16. The network wireless device 16 receives the measurement information and transmits it to the information processing device 20 via the communication line 18. The information processing device 20 receives the measurement information from the network wireless device 16 via the communication line 18.

The information processing apparatus 20 obtains the distance measurement value _r 1 ~r ₃ from the measurement information, performs distance correction processing with respect to the distance measure _r 1 ~r _3. The distance correction process is a process of sequentially performing correction on two distance measurement values out of the _three distance measurement values r _{1 to} r ₃ for three kinds of combinations in which two of the three distance measurement values are selected. The two previously measured distance measurement values are used for the correction of the distance measurement values that follow.

The information processing device 20 stores in advance the positions of the fixed stations 14-1 to 14-3. The information processing device 20 obtains the position of the wireless terminal 12 using the distance measurement values r ₁ , r ₂ and r ₃ that have been subjected to the distance correction processing. That is, the position of the fixed station 14-1 centered _{P 1,} the distance measurement value _{r 1} and the circle _{C 1} that a radius, position the center _{P 2} of fixed station 14-2, the distance measurement value _{r 2} radius a circle _{C 2} that obtains the center _{P 3} the position of the fixed station 14-3, the distance measurement value _{r 3} of the intersection between the circle _{C 3} whose radius as a position of the wireless terminal 12.

(2-2) Distance Correction Processing The distance correction processing will be described. The information processing device 20 includes, in addition to the positions of the fixed stations 14-1 to 14-3, the distance d ₁₂ between the fixed station 14-1 and the fixed station 14-2, the fixed station 14-2 and the fixed station 14-2. the distance _{d 23} between 14-3, and the distance _{d 31} between the fixed station 14-3 and the fixed station 14-1 are stored. These distances may be calculated by the information processing device 20 based on the positions of the fixed stations 14-1 to 14-3.

The information processing apparatus 20, compared distance measure r ₁ and r _2, subjected to a geometrical correction process described below, corrects the distance measurement value r ₁ and r _2. Next, the information processing apparatus 20 performs a geometric correction on the distance measurement value _{r 2} and _{r 3,} corrects the distance measurement value _{r 2} and _{r 3.} Furthermore, the information processing apparatus 20 performs a geometric correction for the distance measurement _{r 3} and _{r 1,} corrects the distance measurement value _{r 3} and _{r 1.}

The geometric correction process for the distance measurement values r _i and r _j will be described. Here, i and j are two different integers selected from integers 1-3. The information processing apparatus 20, centered on the position _{P i} of the fixed station 14-i, the distance measured values _{r i} and the circle _{C i} whose radius, centered at the position _{P j} of the base station 14-j, the distance measurement value r analyzing the geometric relationship between the circle C _j for the _j and radius. There are three combinations of i and j, i=1 and j=2, i=2 and j=3, and i=3 and j=1. There are five geometrical relationships as follows.

Relationship (i) ¥ _{C i} and the circle _{C j} intersect at two points, the relation relation (ii) yen _{C i} is enclosing circle _{C j} to (iii) yen _{C j} is enclosing circle _{C i,} (iv) The relationship in which the circle C _i and the circle C _j do not intersect and one is not included in the other, and (v) the relationship in which the circle C _i and the circle C _j are in contact with each other at one point, the above description (i) The geometrical relationships of (v) are (i) two-point crossing relationship, (ii) C _i C _j inclusive relationship, (iii) C _j C _i inclusive relationship, (iv) isolation relationship, and (v) It is called a one-point contact relationship. FIG. 2 shows a circle C _i and a circle C _j that have a two-point crossing relationship. FIG. 3 shows a circle C _i and a circle C _j having a C _i C _j inclusion relationship. FIG. 4 shows a circle C _i and a circle C _j having a C _j C _i inclusion relationship. FIG. 5 shows a circle C _i and a circle C _j that are in an isolated relationship. In FIG. 6, a circle C _i and a circle C _j that are in a one-point contact relationship are shown.

The information processing device 20 geometrically determines the circles C _i and C _j based on the distance d _ij between the fixed station 14-i and the fixed station 14-j, the distance measurement value r _i, and the distance measurement value r _j. It is determined which of the above five geometric relationships the relationship is.

(A) When r _i <d _ij and r _j <d _ij hold, the information processing device 20 determines the geometrical relationship as follows.
(A1) When r _i +r _j >d _ij holds, the circle C _i and the circle C _j have a two-point crossing relationship.
(A2) When r _i +r _j <d _ij holds, the circle C _i and the circle C _j are in an isolated relation.

(B) When r _i >d _ij and r _j <d _ij hold, the information processing device 20 determines the geometrical relationship as follows.
(B1) When r _i <r _j +d _ij holds, the circle C _i and the circle C _j have a two-point crossing relationship.
(B2) When r _i >r _j +d _ij holds, the circle C _i and the circle C _j have a C _i C _j inclusive relation.

(C) When r _i <d _ij and r _j >d _ij hold, the information processing device 20 determines the geometrical relationship as follows.
(C1) When r _j <r _i +d _ij holds, the circle C _i and the circle C _j have a two-point crossing relationship.
(C2) When r _j >r _i +d _ij holds, the circle C _j and the circle C _i have a C _j C _i inclusive relation.

(D) When r _i >d _ij and r _j >d _ij are satisfied and further r _i >r _j is satisfied, the information processing device 20 determines the geometrical relationship as follows. ..
When (d1) r _i <r _j +d _ij holds, the circle C _i and the circle C _j have a two-point crossing relationship.
When (d2) r _i >r _j +d _ij holds, the circle C _i and the circle C _j have a C _i C _j inclusive relation.

(E) When r _i >d _ij and r _j >d _ij are satisfied and further r _i <r _j is satisfied, the information processing device 20 determines the geometrical relationship as follows. ..
(E1) When r _j <r _i +d _ij holds, the circle C _i and the circle C _j have a two-point crossing relationship.
(E2) When r _j >r _i +d _ij holds, the circle C _j and the circle C _i have a C _j C _i inclusive relation.

(F) When none of the above conditions (a) to (e) is satisfied, the information processing apparatus 20 determines that the circle C _i and the circle C _j have a one-point contact relationship.

When the circle C _i and the circle C _j have a two-point crossing relationship or a one-point contact relationship, the information processing device 20 maintains the distance measurement values r _i and r _j as they are.

When the circle C _i and the circle C _j have a C _i C _j inclusive relation or a C _j C _i inclusive relation, the information processing device 20 sets the distance measurement value r _i and the distance measurement value r _{j according} to (Equation 1). to correct.

[Equation 1]
r _i ←r _i ·d _ij /(|r _i −r _j |)
r _j ←r _j ·d _ij /(|r _i −r _j |)

However, the symbol “←” means updating the value on the left side by the mathematical formula on the right side. In this way, when the circle C _i and the circle C _j have a C _i C _j inclusive relation or a C _j C _i inclusive relation, the distance estimated values r _i and r _j are corrected according to (Equation 1), The geometrical relationship between the circle C _i and the circle C _j is a one-point contact relationship.

When the circle C _i and the circle C _j have an isolation relationship, the information processing device 20 _updates the distance measurement value r _i and the distance measurement value r _{j according} to (Equation 2).

[Equation 2]
r _i ←r _i ·d _ij /(r _i +r _j )
r _j ←r _j ·d _ij /(r _i +r _j )

When the circle C _i and the circle C _j are in the isolated relation, the distance measurement value r _i and the distance measurement value r _j are corrected according to (Equation 2), so that the geometric relation between the circle C _i and the circle C _j is obtained. Has a one-point contact relationship.

The information processing device 20 includes a geometric correction process for the distance measurement values r ₁ and r _2, a geometric correction process for the distance measurement values r ₂ and r _{3, and} a geometric correction process for the distance measurement values r ₃ and r ₁ . Correction processing is sequentially executed. That is, the information processing device 20 sequentially performs geometric correction on two distance measurement values out of the three distance measurement values for three types of combinations in which two of the three distance measurement values are selected.

The information processing device 20 may repeatedly execute the distance correction process including such a series of geometric correction processes. The distance correction process is repeated until the distance measurement values r ₁ , r ₂ and r ₃ converge. The determination as to whether or not the distance measurement values r ₁ , r ₂ and r ₃ have converged by the distance correction process that is repeatedly executed is performed by the convergence determination that indicates the tendency of the magnitudes of the distance measurement values r ₁ , r ₂ and r _3. It may be performed based on the value. For example, any one of the distance measurements _r 1, _{r 2} and the square sum or distance measure _r 1 of _{r 3, r 2} and _{r 3} may as convergence criterion value. In this case, when the distance correction process is repeated, the absolute value of the difference between the convergence determination value obtained by the distance correction process performed first and the convergence determination value obtained by the distance correction process performed next is predetermined. Until the value becomes less than the threshold value of

FIG. 7 shows circles C _{1 to} C ₃ intersecting at one point by the distance correction processing. The position of the point Q shown in the figure is obtained as the position of the wireless terminal 12.

The information processing device 20 obtains the position of the wireless terminal 12 using the distance measurement values r ₁ , r ₂ and r ₃ that have been subjected to the distance correction process. That is, the position of the fixed station 14-1 centered _{P 1,} the distance measurement value _{r 1} and the circle _{C 1} that a radius, position the center _{P 2} of fixed station 14-2, the distance measurement value _{r 2} radius a circle _{C 2} that obtains the center _{P 3} the position of the fixed station 14-3, the distance measurement value _{r 3} of the intersection between the circle _{C 3} whose radius as a position of the wireless terminal 12. The position of the wireless terminal 12 is represented by a two-dimensional coordinate value.

(2-3) Effects Radio signals transmitted and received between the wireless terminal 12 and each fixed station should not be transmitted and received well by the wireless terminal 12 and each fixed station due to the influence of accidental obstacles and multipaths. There is. Therefore, the initially obtained distance measurement values r _{1 to} r ₃ may include an error, and the positioning accuracy of the wireless terminal 12 may decrease. According to the positioning system 10 according to the present embodiment, _three circles centering on the positions P _{1 to} P ₃ of the fixed stations 14-1 to 14-3 and having distances r _{1 to} r ₃ as radii are 1 point. The distance measurement values r _{1 to} r ₃ are corrected so as to intersect with each other. As a result, the position of the wireless terminal 12 can be obtained with high accuracy.

(3) Experimental Results An experiment was conducted on the wireless terminal 12 whose actual position is represented by (x, y)=(0.5, 1.5). The position determined by the distance measurement values r _{1 to} r ₃ before correction was (x, y)=(−0.74, −0.7). The error is between the position represented by (x, y)=(0.5, 1.5) and the position represented by (x, y)=(−0.74, −0.7). The distance is 2.52.

On the other hand, the position obtained from the corrected distance measurement values r _{1 to} r ₃ was (x, y)=(−0.2, −0.31). The error is between the position represented by (x, y)=(0.5, 1.5) and the position represented by (x, y)=(-0.2, -0.31). Is 1.38, which is 1.38. The error was reduced from 2.52 to 1.38 by one distance correction process. It is considered that the error is reduced by repeatedly performing the distance correction processing a plurality of times.

(4) Hardware Example FIG. 8 shows an example of hardware of the wireless terminal 12. The wireless terminal 12 includes a wireless unit 32 and an information processing unit 34. The wireless unit 32 wirelessly transmits the information acquired from the information processing unit 34 to the fixed stations 14-1 to 14-3 or the network wireless device 16. Further, the wireless signal transmitted from the fixed stations 14-1 to 14-3 or the network wireless device 16 is received, and the information included in the wireless signal is output to the information processing unit 34.

The information processing section 34 includes a distance measuring section 36 and a measurement information generating section 38. The information processing unit 34 may include a processor that executes a program. In this case, the information processing unit 34 internally configures the distance measuring unit 36 and the measurement information generating unit 38 by executing the program.

The distance measuring unit 36 transmits/receives a radio signal to/from each of the fixed stations 14-1 to 14-3 via the wireless unit 32 to obtain distance measurement values r _{1 to} r ₃ to each fixed station. The measurement information generation unit 38 generates measurement information including the distance measurement values r _{1 to} r ₃ and wirelessly transmits the measurement information to the network wireless device 16 via the wireless unit 32.

FIG. 9 shows an example of hardware of the information processing device 20. The information processing device 20 includes an interface 50 and an information processing unit 52. The information processing device 20 may be a computer that functions as a server. The interface 50 connects the information processing section 52 to the communication line 18. The information processing unit 52 includes an information acquisition unit 54, a distance correction unit 56, and a position determination unit 58. The information processing unit 52 may include a processor that executes a program. In this case, the information processing unit 52 configures each component (the information acquisition unit 54, the distance correction unit 56, and the position determination unit 58) inside by executing the program.

The information acquisition unit 54 receives the measurement information from the communication line 18 via the interface 50, and acquires the distance measurement values r _{1 to} r ₃ obtained for each fixed station from the measurement information. Distance correcting unit 56 executes the correction for the two distance measurements of the three distance measurement values r ₁ ~r _3, sequentially for three combinations for selecting two of three distance measurement values r ₁ ~r ₃ The distance correction process is executed. The position determination unit 58 calculates the position of the wireless terminal 12 based on the _three distance measurement values r _{1 to} r 3 after the distance correction process is executed.

The geometric correction processing is performed on the determination result of the geometrical relationship between the circles C _i and the circles C _j , the two distance measurement values, and the distance between the two fixed stations from which the two distance measurement values are obtained. Based on the two distance measurements. That is, the geometric correction process is centered on one position of the two fixed stations 14-i and 14-j and corresponds to one fixed station of the two distance measurement values r _i and r _j. A circle whose radius is the distance measurement value and a circle whose center is the other position of the two fixed stations and whose radius is the distance measurement value corresponding to the other fixed station of the two distance stations are 1 It includes the process of correcting the two distance measurements so that they touch at points.

(5) Other Embodiments FIG. 10 shows a positioning system 100 according to the second embodiment. In the positioning system 100, the fixed stations 14-1 to 14-3 are connected to the communication line 18. Each of the fixed stations 14-1 to 14-3 acquires the distance measurement values r _{1 to} r ₃ by wireless communication with the wireless terminal 12. The fixed stations 14-1 to 14-3 respectively transmit the distance measurement values r _{1 to} r ₃ to the information processing device 20 via the communication line 18. Further, at least one of the fixed stations 14-1 to 14-3 collectively obtains the distance measurement values r _{1 to} r ₃ by wireless communication with the wireless terminal 12 and communication with another fixed station. You may. Of the fixed stations 14-1 to 14-3, the fixed station acquired distance measurement _r 1 ~r ₃ together may transmit the distance measurement value _r 1 ~r ₃ to the information processing apparatus 20 via the communication line 18 To do. The information acquisition unit 54 illustrated in FIG. 9 acquires the distance measurement values r _{1 to} r ₃ from at least one of the three fixed stations 14-1 to 14-3 via the interface 50.

The positioning system may be provided with four or more fixed stations. In this case, the position of the wireless terminal 12 is measured using three fixed stations selected from four or more fixed stations.

10, 100 positioning system, 12 wireless terminals, 14-1 to 14-3 fixed station, 16 network wireless device, 18 communication line, 20 information processing device, 32 wireless unit, 34,52 information processing unit, 36 distance measuring unit, 38 measurement information generation part, 50 interface, 54 information acquisition part, 56 distance correction part, 58 position determination part.

Claims (3)

An information acquisition process of acquiring a distance measurement value between each of the three fixed stations and the wireless terminal from at least one of the three fixed stations, or the wireless terminal;
A distance correction process of sequentially correcting two distance measurement values out of the three distance measurement values for three combinations selecting two of the three distance measurement values;
And a position determination process for determining the position of the wireless terminal based on the three distance measurement values after the distance correction process is executed,
The distance correction process is
The geometric relationship of two circles having the positions of the two fixed stations for which the two distance measurement values are obtained as their centers and having the two distance measurement values as their respective radii are determined, and the geometric A positioning device comprising a geometric correction process for correcting the two distance measurement values based on a determination result regarding a physical relationship. The positioning device according to claim 1,
The geometric correction process is
The two distance measurement values are corrected based on the determination result of the geometrical relationship, the two distance measurement values, and the distance between the two fixed stations from which the two distance measurement values are obtained. A positioning device comprising: In the positioning device according to claim 1 or 2,
The geometric correction process is
A circle whose center is one of the two fixed stations and whose radius is the distance measured value corresponding to one of the two fixed stations,
Centering the other position of the two fixed stations, and of the two distance measurement values, a circle having a radius of the distance measurement value corresponding to the other fixed station is in contact at one point,
A positioning device comprising a process of correcting the two distance measurement values.