Method for measuring location of radio frequency identification reader by using beacon

Abstract

The present invention relates to a method for measuring a location of a radio frequency identification (RFID) reader by using beacons, and an RFID system for measuring a location of a moving RFID reader in an RFID system comprising: a plurality of beacon devices for emitting beacons; an RFID tag for transmitting pre-stored information by using radio frequency identification; and an RFID reader for calculating a current location using a plurality of at least three beacons wherein the RFID reader receives the plurality of beacons from the plurality of beacon devices while moving, and receiving the information from the RFID tag by using the radio frequency identification. According to the present invention, it is possible to increase the accuracy of the location measurement of a moving RFID reader in an RFID system because the location of the RFID reader is measured in consideration of propagation environments.

Description

The first to third beacon devices 110, 112, and 114 may also be referred to as beacon transmitters.
(x2−x)²+(y2−y)²+(z2−z)²=(d2−err)
(x3−x)²+(y3−y)²+(z3−z)²=(d3−err)   [Math FIG. 1]

In equation 1, “err” represents an error with respect to distance, and is a constant which can be determined according to a tolerable error rate in the current location.

Also, “x1,” “y1,” “z1,” and “d1” correspond to the first reference location information and the relative distance from the first beacon device 110, and are constants which can be identified from the first beacon. “x2,” “y2,” “z2,” and “d2” correspond to the second reference location information and the relative distance from the second beacon device 112, and are constants which can be identified from the second beacon. “x3,” “y3,” “z3,” and “d3” correspond to the third reference location information and the relative distance from the third beacon device 114, and are constants which can be identified from the third beacon.

Therefore, since only “x,” “y,” and “z” correspond to variables to be found in three equations shown in equation 1, the three-dimensional coordinates (x, y, z) of the current location of the RFID reader 120 can be obtained by solving the three simultaneous equations.

As described above, according to the present invention, at least three beacon devices emitting beacons are fixedly installed in the RFID system, and each beacon device 110, 112, and 114 emits a beacon, including reference location information of the beacon device and signal-intensity-to-distance information where the propagation environment of the circumstances of the beacon device is reflected, which helps the RFID reader 120 to determine the current location. Then, the RFID reader 120 measures the signal intensities of a first beacon, a second beacon, and a third beacon, which have been received from the beacon devices 110, 112, and 114, respectively, identifies relative distances corresponding to the signal intensities of the beacons, respectively, and calculates the current location by using three-dimensional coordinates of each beacon device 110, 112, and 114, so that the moving RFID reader 120 can measure its own location, and furthermore, can exactly measure the location because the propagation environment of circumstances of each beacon device 110, 112, and 114 can be reflected.

FIG. 5 is a view explaining an example of a procedure of measuring a moving speed and a moving direction by an RFID reader according to an exemplary embodiment of the present invention.

As described above with reference to FIGS. 4A and 4B, the RFID reader 120 according to an exemplary embodiment of the present invention can measure its own current location by using at least three beacon devices.

Meanwhile, the RFID reader 120 can freely move in the RFID system, and can continuously measure its own location, even while it is moving. Hereinafter, a procedure where the RFID reader 120 calculates or measures its moving speed and its moving direction while the RFID reader 120 is moving in the RFID system will be described.

When it is assumed that the RFID reader 120 has moved from point A to point B, point A corresponds to three-dimensional coordinates (x1, y1, z1), and point B corresponds to three-dimensional coordinates (x2, y2, z2), as shown in FIG. 5, a moving speed of the RFID reader 120 may be derived as equation 2.

$\begin{array}{cc}\frac{\sqrt{{\left(x2-x1\right)}^2{\left(y2-y1\right)}^2+{\left(z2-z1\right)}^2}}{\mathrm{movement}\mathrm{time}}& \left[\mathrm{Math}\mathrm{Figure}2\right]\end{array}$

That is, since a speed can be expressed as a ratio of a distance to a time, the RFID reader 120 can calculate a moving speed by dividing its own moving distance by its own moving time. This is to calculate a moving speed by dividing a distance from a pre-moving location to a post-moving location by a moving time.

Also, a moving direction of the RFID reader 120 may be derived as equation 3.
{right arrow over (d)}=(x2−x1,y2−y1,z2−z1)   [Math FIG. 3]

That is, a vector from x-axis, y-axis, and z-axis coordinates of a pre-moving location to x-axis, y-axis, and z-axis coordinates of a post-moving location corresponds to a moving direction.

Therefore, the RFID reader 120 can calculate its moving speed and its moving direction by equations 2 and 3, can use the calculated moving speed and moving direction to confirm if the RFID reader 120 is accurately moving toward a destination, and can utilize the calculated moving speed and moving direction to calculate and estimate a direction and a speed in which the RFID reader 120 is to move to the destination.

Although an exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Therefore, the embodiment disclosed in the present invention has been described not for limiting the scope of the invention, but for describing the invention. Accordingly, the scope of the invention is not to be limited by the above embodiment but by the claims and the equivalents thereof. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A radio frequency identification (RFID) system for measuring a location of an RFID reader by using a beacon short-range wireless communication system, the short-range wireless communication system comprising:

a plurality of beacon devices transmitters, each of which is fixed at a reference location and comprises an antenna, a processor and configured to create a database of a memory having computer executable instructions stored thereon that, when executed by the processor, cause each of the beacon transmitters to:

emit a beacon, wherein each of the beacon transmitters stores information about signal intensities to distances by measuring of the beacon, the information about the signal intensities of the beacon according to distance distances having been obtained based on a propagation environment and emit the beacon which around each of the beacon transmitters, wherein the beacon includes information about the reference location of each beacon device of the plurality of the beacon transmitters and the information about the signal intensities to distances from each beacon device; and

an RFID reader configured to receive the beacon a means for

receiving beacons from each of the plurality of beacon devices transmitters,

measure a signal intensity of each received beacon, determine a distance from each beacon device by analyzing the measured signal intensity on the basis of the extracting information about signal intensities to distances included in the received beacon and to calculate a current location thereof by using both from the received beacons,

measuring signal intensities of the received beacons,

determining distances from the respective beacon transmitters based on the measured signal intensities and the information about the signal intensities to distances, and

calculating the location of the means based on reference location locations of the plurality of beacon transmitters and the determined distance distances from each beacon device the plurality of beacon transmitters,

wherein the RFID reader calculates means is configured to calculate the current location of the means through a triangulation method using based on the reference location locations of each beacon device the plurality of beacon transmitters and the determined distance distances from each beacon device the beacon transmitters.

2. The system as claimed in claim 1, wherein the RFID reader receives the plurality of beacons from at least beacon transmitters include three beacon devices among the plurality of beacon devices or more beacon transmitters.

3. The system as claimed in claim 2, wherein, when receiving the plurality of beacons from said at least more than three beacon devices transmitters, the RFID reader means calculates the current location by of the means using three beacons having relatively higher signal intensities among the plurality of received beacons.

4. The system as claimed in claim 1, wherein the RFID reader calculates means is configured to store the location of the means at a first moment as a pre-moving first location and the location and a post-moving thereof at a second moment as a second location, and calculates the first moment being different from the second moment, and calculate a speed and a moving direction of the means from the pre-moving first location to the post-moving second location, based on a distance from the first location to the second location and a time difference between the first moment and the second moment.

5. The system as claimed in claim 4, wherein the RFID reader measures a movement time from the pre-moving location to the post-moving location, calculates a distance from the pre-moving location to the post-moving location, and then calculates a ratio of the distance to the time as the speed means is configured to calculate the moving direction by calculating a vector from the first location to the second location.

6. The system as claimed in claim 4, wherein the RFID reader calculates the direction by calculating a vector from the pre-moving location to the post-moving location 1, wherein the short-range wireless communication system is a radio frequency identification (RFID) system, and the beacon transmitters are beacon devices.

7. A method for calculating a current location of a radio frequency identification (RFID) reader in an RFID system by using a beacon of a beacon device in a plurality of beacon devices each of which is fixed at a reference location and configured to create a database of information about signal intensities to distances by measuring signal intensities of the beacon according to distance based on a propagation environment and emit the beacon which includes information about the reference location of each beacon device and the information about signal intensities to distances from each beacon device the location of the means using the system of claim 1, the method comprising the steps of:

(a) receiving a plurality of beacons from the plurality of beacon devices transmitters fixed at the reference locations respectively;

extracting the information about the signal intensities to distances from the received beacons;

(b) measuring signal intensities of the plurality of beacons; and (c) received beacons;

determining distances from the plurality of beacon devices by analyzing the measured signal intensities on the basis of the information about signal intensities to distances included in the plurality of received beacons respective beacon transmitters based on the measured signal intensities and the information about the signal intensities to distances; and

(d) calculating the location of each beacon device by using the reference locations of the plurality of beacon devices and the determined distances in step (c) from the plurality of beacon devices the means through a triangulation method based on the reference locations of the beacon transmitters and the determined distances from the beacon transmitters.

8. The method as claimed in claim 7, where step (c) comprising the steps of:

(c1) identifying information about the reference locations of the plurality of beacon devices, which is included in the plurality of beacons, by analyzing the plurality of beacons; and

(c2) calculating the location through a triangulation method using the reference locations of the plurality of beacon devices and the determined distances from the plurality of beacon devices further comprising:

storing the location of the means at a first moment as a first location;

storing the location thereof at a second moment as a second location, the first moment being different from the second moment; and

calculating a speed and a moving direction of the means from the first location to the second location, based on a distance from the first location to the second location and a time difference between the first moment and the second moment.

9. The method as claimed in claim 7, further comprising, after step (c), the steps of:

(d) moving the current location to a next location; and

(e) calculating a moving speed and a moving detection from the current location to the next location wherein the plurality of beacon transmitters are beacon devices.

10. A method for calculating a current the location of a radio frequency identification (RFID) reader the means of claim 1, the method comprising the steps of:

receiving a beacon at the RFID reader beacons from each of at least three beacon devices a plurality of beacon transmitters which are disposed near the RFID reader, each beacon including first means, wherein the beacons include information about a reference location locations of each beacon device and second the beacon transmitters and information about signal intensities to distances from each beacon device, respectively;

retrieving at the RFID reader the first information and the second information from each received beacon extracting information about the signal intensities to distances from the received beacons;

measuring at the RFID reader a signal intensity of each received beacon signal intensities of the received beacons;

determining at the RFID reader a distance from each beacon device by analyzing the measured signal intensity on the basis of the retrieved second information distances from the respective beacon transmitters based on the measured signal intensities and the information about the signal intensities to distances; and

calculating at the RFID reader the current location by using both the retrieved first information about the reference location and the determined distance,

wherein the each beacon device has a database of information about signal intensities to distances by measuring signal intensities of the beacon according to distance based on a propagation environment of the means through a triangulation method based on the reference locations of the beacon transmitters and the determined distances from the beacon transmitters.

11. The method as claimed in claim 10, wherein the beacon transmitters are beacon devices.

12. The method as claimed in claim 10, wherein the beacon includes at least one of an RF signal, a Zigbee signal and a Bluetooth signal.

13. The method as claimed in claim 1, wherein the beacon includes at least one of an RF signal, a Zigbee signal and a Bluetooth signal.

14. The system as claimed in claim 7, wherein the beacon includes at least one of an RF signal, a Zigbee signal and a Bluetooth signal.