WO2011071199A1

WO2011071199A1 - System and method for position-tracking

Info

Publication number: WO2011071199A1
Application number: PCT/KR2009/007380
Authority: WO
Inventors: 박현수
Original assignee: (주)한울옵틱스
Priority date: 2009-12-10
Filing date: 2009-12-10
Publication date: 2011-06-16

Abstract

The present invention relates to a system and method for position-tracking, and more particularly, to a system and method for position-tracking without using a mathematical equation such as a conventional triangulation equation, but by enlarging or shrinking an intuitive graphical circle to reduce load on a server and to offset radio wave errors that occur indoors, outdoors, or due to weather conditions. The position-tracking system of the present invention comprises: receivers arranged in a regular lattice to receive tag radio waves; a database configured to store position signal intensity data received through a gateway from the receivers that receive a position signal from a tag; and a position-tracking server configured to calculate distances from three or more of the receivers on the basis of the position signal intensity data, and to generate three or more circles having the calculated distances as radii, wherein the position-tracking server selects a maximum overlapping region when an overlapping region exists among the circles, and when no overlapping region exists among the circles, the position-tracking server incrementally adds a preset general position step value to the calculated distances so as to generate circles having respective radii of the incrementally added sums, until the circles overlap one another, so as to select a maximum overlapping region among the circles.

Description

Location tracking system and method

The present invention relates to a position tracking system and a method thereof, and more particularly, to reduce the load on the server by expanding or reducing the intuitive graphical circle without using a formula such as conventional triangulation, indoor or outdoor or The present invention relates to a location tracking system and method capable of offsetting errors in radio waves due to weather and the like.

In general, triangulation is a simple geometric method and is the most commonly used method for estimating the real-time position of an object moving on a two-dimensional plane in a position tracking system (RTLS).

At least three reference points are required to estimate the real time position of a moving object on a two-dimensional plane (hereinafter, only a two-dimensional plane is assumed). Such reference points are referred to as AP1, AP2, and AP3, and the coordinates of each AP are referred to as (x ₁ , y ₁ ), (x ₂ , y ₂ ), and (x ₃ , y ₃ ) as shown in FIG. 1.

In addition, the moving object is represented by M, the current position is called (x, y), and the distance from the moving object M to three reference points is called d ₁ , d ₂ , d ₃ .

Thus, the distance between each reference point from the moving object M can be simply calculated by the Pythagorean theorem. In other words,

Equation 1

Equation 2

Equation 3

Becomes Here, the values of d ₁ , d ₂ , d ₃ can be obtained by various methods. For example, it may be obtained using the relationship with the received signal strength RSSI, or may be obtained by using the arrival time TOA or the arrival time difference TDOA. Therefore, it is assumed here that the values of d ₁ , d ₂ and d ₃ are known. In addition, since the coordinate values of three reference points are also known, the value of (x, y) which is the current position of a moving object can be calculated | required using said Formula (1)-Formula (3).

In addition, when the position estimation by the triangulation method using the received signal strength is described, as described above, the principle of the triangulation method is applied as it is, and only a process of obtaining a distance between three reference points from the moving object will be further described.

Using received signal strength, the distance from the moving object to the reference point is Friis' formula

Equation 4

Obtained from Friis's formula in equation (4) is to find the path loss in free space, where λ represents the wavelength of the radio wave and uses the same units as the distance d. If equation (4) is expressed for the distance d between two points,

Equation 5

Becomes Where c is the speed of propagation and f is the frequency.

For example, in a WLAN-based positioning system using the 2.4 GHz band, if the loss of the signal transmitted by the mobile object is 60 dB and the propagation speed of the wireless signal in the air is 3 × 10 ⁸ [m / sec], two points The distance d between

Equation 6

Becomes

For the other two reference points, the distance is calculated in the same way, and substituted into equations (1) to (3) to obtain the coordinate values of (x, y), which are the current positions of the moving object.

However, in the conventional triangulation method described above, if the load is applied to the server using a distance calculation formula and the calculation is repeated roughly as shown in Eq. (6), it is difficult to accurately track the location. Since there is a situation showing a deviation, there was a problem that is a technology that is difficult to actually use.

An object of the present invention is to provide a location tracking system that can reduce the load on the server by expanding or reducing the intuitive graphical circle, the operation speed is fast, and can cancel the error of the radio wave due to the weather.

An object of the present invention is to provide a location tracking system that can be usefully used for shopping or tourist attractions, museums, container location tracking, construction site material management.

The present invention is a position tracking system including receivers receiving a radio wave of a tag distributed in a grid form of a uniform interval, receiving the position signal strength data from the receiver receiving the position signal generated by the tag through the gateway A database to store and derive a distance separated from three or more of the receivers based on the data to generate three or more circles with a radius of the derived distance, the maximum overlapping area if there is an overlapping area Or if there is no overlapping area, create a stepped circle with a radius that adds the general location step value to the derived distance until there is an overlapping area with a preset general location step value. It includes a location tracking server of your choice.

After the maximum overlap region is selected, the location tracking server generates a stepped circle having a radius of the derived distance as a precision location step value minimizing the general location step value when more precise location determination is required.

The location tracking server receives an area value indicating the location tracking precision from the terminal and selects a maximum overlapping area from an overlapping area corresponding to the area value.

The tag is preferably used attached to the mobile terminal.

The present invention provides a method of setting a pixel, a step value and an area value, receiving a radio wave of a tag through a receiver distributed in a uniformly spaced grid, and receiving a position signal at which the tag oscillates. Receiving data and storing the data in a database, receiving the data through a location tracking server, deriving a distance spaced from the receiver based on the data, and determining the derived distance through the location tracking server. Creating three or more circles with a radius, selecting a maximum overlapping area if there is an overlapping area, and if there is no overlapping area through the location tracking server until the overlapping area exists with a preset general position step value A stepped circle of radius is generated by adding the general position step value to the derived distance, so that the overlapped area is If reallocation comprises a step of selecting a maximum overlapping area.

The present invention further includes the step of generating a stepped circle having a radius of the derived distance with a precision position step value which minimizes the general position step value after the maximum overlapping area is selected, when more accurate precision positioning is required.

The present invention may further include receiving a region value from the terminal and selecting a maximum overlap region in the overlap region corresponding to the region value.

The present invention can reduce the load on the server by expanding or reducing the intuitive graphical circle without using a formula such as a conventional triangulation, fast operation speed, and has the effect of offsetting the error of the radio wave due to weather have.

The present invention can track the exact location in software only by the existing receiver, etc. without additional configuration, there is an effect that can be usefully used for shopping places, tourist attractions, museums, container location tracking, construction site materials management.

1 is a view for explaining the triangulation according to the position tracking according to the conventional invention.

Figure 2 is a view showing the overall configuration around the location tracking server of the location tracking system according to the present invention and the configuration module of the location tracking server.

3 is a diagram illustrating a distance according to signal strength by receiving position signal strength data centering on receivers of the position tracking system according to the present invention as a graphic circle.

Figure 4 shows that the position tracking system according to the present invention generates a stepped circle of radius which adds the general position step value to the derived distance until there is an overlapping area with a preset general position step value.

FIG. 5 shows the creation of a stepped circle of radius minus the normal position step value of FIG.

FIG. 6 is a diagram illustrating that a predetermined portion is overlapped and the weight is calculated in an overlapped region according to the results of FIGS. 4 and 5.

Figure 7 shows that the location tracking system according to the present invention selects the maximum overlapping area from the weights in the overlapping area.

8 is a view showing that the position tracking system according to the present invention extends to an overlapping area corresponding to an area value and selects a center among the maximum overlapping areas;

9 is a flowchart schematically showing a sequence of a location tracking method according to the present invention.

** Description of the main parts of the drawing **

10: tag 20: receiver

30: database 40: location tracking server

50: terminal

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

Position tracking system according to the present invention is a device connected to the receivers 20 for receiving the radio wave of the tag 10 is distributed in a grid form of a uniform interval, divided into a database 30 and the location tracking server 40 Lose.

First, terms mainly used in the present invention are defined.

Tag: A device that can be attached to a mobile terminal and includes a personal identification ID and sends a schedule radio wave accordingly.

Receiver: A device that receives a radio wave of a tag by distributing it in the form of a lattice of evenly spaced pixels.

Pixel: Location tracking information in the minimum unit determined according to the screen resolution. For example, when the screen resolution is 1024x768 pixels, the map is scaled down and the distance corresponding to one pixel is set as the minimum distance.

Step value: This is a constant that is set in advance and stored in the server.It is a general position step value for expanding or reducing a circle with a general pixel size, and a precise position step using a minimum pixel size (depending on indoor or outdoor). It is divided into chi.

Area value: A constant that is set in advance and stored in the server. It indicates the location tracking accuracy, and the larger the area value, the more the location can be tracked.

2 is a view showing the overall configuration of the location tracking server and the configuration module of the location tracking server according to the present invention, Figure 3 is a location signal strength around the receiver of the location tracking system according to the present invention 4 is a diagram illustrating a distance according to signal strength as a graphic circle, and FIG. 4 illustrates a general position step at the derived distance until an overlapping region exists at a preset general position step value according to the present invention. Figure 5 shows the creation of a stepped circle of the sum of the radiuses, Figure 5 is a view showing the creation of a stepped circle of the radius minus the normal position step value, as opposed to Figure 4, Figure 6 shows the results of Figures 4 and 5 Fig. 7 shows the calculation of the weights in the overlapped areas by overlapping a certain portion, and Fig. 7 shows the position tracking system according to the present invention. FIG. 8 is a diagram illustrating a selection of a maximum overlapping area from weights in this overlapping area, and FIG. 8 is a diagram illustrating a position tracking system according to the present invention extending to an overlapping area corresponding to an area value and selecting a center among the maximum overlapping areas. .

As shown in FIG. 2, the database 30 receives and stores received signal strength indication (RSSI) data through a gateway from receivers 20 that receive a position signal generated by the tag 10. Device. That is, as shown in FIG. 3, each position signal strength is represented in a graphic form in a display apparatus in which the position of the receiver 20 is pixelated.

As shown in Figs. 4 and 5, the position tracking server reduces the stepwise circle of the radius obtained by adding the general position step value to the derived distance until there is an overlapping area with the preset general position step value represented in Fig. 3. Or by expanding (S1-> S2-> S3).

Specifically, as shown in FIG. 6, the location tracking server derives a distance spaced from three or more receivers R2, R3, and R5 among the receivers 20 based on the data, and thus the derived distance. Create three or more circles with a radius and select the maximum overlapping area if there is an overlapping area, or if the overlapping area does not exist, set the normal location at the above-derived distance until the overlapping area exists with the preset general location step value. It is a server that creates a stepped circle of the sum of the step values and selects the maximum overlap area if there is an overlap area.

Here, the general position step value is generally 10 pixels or 5 pixels, that is, 23 m or 11.5 m in width.

In addition, after the maximum overlap region is selected, the location tracking server 40 generates a stepped circle whose radius is the derived distance as a precision location step value which minimizes the general location step value when more accurate location determination is required.

Alternatively, as another embodiment of the present invention, if the location tracking server 40 has an overlapping area, if the overlapping area is wide, each circle is reduced to the general location step until the size is large enough to correspond to the general location step value. If the overlap region is small enough to correspond to the normal position step value, the position is converted into coordinates.

If there is no overlapping area, the location tracking server 40 enlarges each circle to the general location step value until the overlapping area is created, and if the generated overlapping area is as small as the general location step value, the location coordinate is converted into location coordinates. Zoom out again to convert the position coordinates.

7 and 8, when the location tracking server 40 receives the area value from the terminal 50 and wants to increase the processing speed, the location tracking server 40 sets a narrow area value and precisely tracks the location at the request of customers. If necessary, the maximum overlapping region is selected from the overlapping regions corresponding to the above region values as shown in FIG.

That is, in the case of outdoor, the tracking accuracy is 10-20m, and when the minimum pixel is about 5 pixels, the overlapped area becomes wider and the whole area is set as one location. In this case, the area value can be set wider for more precise location tracking. Let's do it.

Hereinafter, a location tracking method according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 9, the pixel, step value and area value are previously set by accessing the location tracking server through the terminal (S110 and S120).

Subsequently, the receiver receiving the position signal from which the tag is oscillated receives the position signal strength data and stores it in a database, receives the data through the position tracking server, and derives the distance from the receiver based on the data. (S130).

A circle having a radius as the derived distance is generated, and a point at which a plurality of circles overlap is selected (S140 and S150).

Finally, the maximum overlapping point is stored, and the position is converted into coordinates and displayed through the display apparatus (S160).

In detail with reference to steps S140 and S150, generating three or more circles having a radius of the derived distance through the location tracking server, selecting a maximum overlapping area if there is an overlapping area, and the location tracking server If there is no overlapping area through, create a stepped circle with a radius that adds the general location step value to the derived distance until the overlapping area exists at a preset general position step value, and selects the maximum overlapping area if there is an overlapping area. Divided into stages.

Claims

A location tracking system including receivers distributed in a uniformly spaced grid to receive radio waves of a tag,

A database for receiving and storing the location signal strength data from the receivers receiving the location signals generated by the tag through the gateway;

Derive a distance separated from three or more of the receivers based on the data to generate three or more circles whose radius is the derived distance, and select a maximum overlap region if there is an overlap region;

If there is no overlapping area, create a stepped circle with a radius that adds the general location step value to the derived distance until the overlapping area exists by using the preset general location step value, and select the maximum overlapping area when the overlapping area exists. server;

Positioning system, characterized in that configured to include.
The method of claim 1,

The location tracking server,

And after the maximum overlapping area is selected, when a more precise position determination is required, a stepped circle having a radius as the derived distance is generated as a precision position step value minimizing the general position step value.
The method of claim 1,

The location tracking server,

And a maximum overlapping area is selected from the overlapping area corresponding to the area value by receiving an area value indicating the location tracking precision from the terminal.
The method of claim 1,

The tag is attached to the mobile terminal is used, the location tracking system.
Setting pixel, step and region values;

Receiving a radio wave of a tag through a receiver distributed in a grid form with uniform intervals;

Receiving location signal strength data at a receiver for receiving a location signal generated by a tag and storing the location signal strength data in a database;

Receiving the data through a location tracking server and deriving a distance from the receiver based on the data;

Generating three or more circles having the derived distance as a radius through the location tracking server, and selecting a maximum overlapping area if there is an overlapping area;

If there is no overlapping area through the location tracking server, a stepped circle having a radius that adds the general location step value to the derived distance until the overlapping area exists at a preset general location step value is generated. Selecting an area;

Position tracking method, characterized in that consisting of.
The method of claim 5,

Generating a stepped circle having a radius of the derived distance as a precision position step value which minimizes the general position step value after the maximum overlapping area is selected;

Position tracking method further comprises a.
The method of claim 5,

Receiving an area value from a terminal and selecting a maximum overlapping area in an overlapping area corresponding to the area value;

Position tracking method further comprises a.