KR102679597B1 - Indoor positioning system and method to minimize positioning error - Google Patents

Abstract

The present invention includes a plurality of beacons that transmit and receive Bluetooth signals; A user terminal that transmits and receives Bluetooth signals with another terminal or the plurality of beacons; a user location measurement unit that measures the current location of the user using trilateration and Bluetooth signals received by the user terminal from at least three of the plurality of beacons; and a user location correction unit that corrects the user's location measured by the user location measurement unit using a Bluetooth signal received from another nearby terminal.

Description

Indoor positioning system and method to minimize positioning error {INDOOR POSITIONING SYSTEM AND METHOD TO MINIMIZE POSITIONING ERROR}

The present invention relates to an indoor positioning system and method, and particularly to an indoor positioning system and method for minimizing positioning errors using Bluetooth packet information.

As smartphones become widely distributed and commercialized, technology that uses GPS to determine the user's location is being widely used. Various systems and functions are being used through this technology. In particular, in the mobile ecosystem, the user's location information is very important, as GPS is used to determine the user's location and provide various information.

GPS is a method of determining the positions of satellites and receivers by receiving signals transmitted from three or more GPS satellites. It was initially developed for military purposes, but is now widely used for civilian purposes as well as military purposes. Meanwhile, the user's location can be determined through GPS, but the location information that can be obtained through GPS is limited. The limitation is that the user's detailed location cannot be confirmed. When a user is located in a specific building, such as a building, the location information of the building itself can be known, but the detailed location in the building cannot be known. In addition, GPS signal reception is not smooth underground, making it difficult to use underground.

To solve these difficulties, beacons and low-energy Bluetooth can be used to obtain detailed information that could not be obtained through existing GPS, and various systems can be implemented using this.

In order to find the indoor location of a user's terminal using a beacon, there must be three or more beacons with fixed positions around the user. The distance to the user is determined using the location and signal strength information of the beacons, and the location is determined by triangulation. Paying is a common method. At this time, due to the inaccuracy of signal strength in various wireless environments, it has the disadvantage of being difficult to apply to industrial fields that require precise position measurement in meters.

In this regard, Korean Patent Publication No. 10-2017-0091811 discloses an indoor location determination method using the RSSI of a Bluetooth beacon and the weight of the pedestrian pattern. In the above prior patent, the user's mobile device receives signals from a plurality of beacons, roughly measures the location of the mobile device, analyzes pedestrian patterns, assigns probabilistic weights, and ensures a detailed location to determine the location of the terminal. .

As described above, a number of prior documents have proposed measuring the user's location indoors using a plurality of beacons. However, Bluetooth signals are very sensitive to the surrounding environment, such as obstacles around the device, weather, and humidity, and the user's location triangulated using beacons has a limitation in that the error is large. Therefore, there is a need for an indoor position measurement system and method that solves the above limitations.

Korean Patent Publication No. 10-2017-0091811

The purpose of the present invention is to provide an indoor positioning system and method that minimizes positioning errors by correcting errors in the user's primary position measured using Bluetooth signals and triangulation. Do it as

In order to achieve the above object, the present invention includes a plurality of beacons for transmitting and receiving Bluetooth signals; A user terminal that transmits and receives Bluetooth signals with another terminal or the plurality of beacons; a user location measurement unit that measures the current location of the user using trilateration and Bluetooth signals received by the user terminal from at least three of the plurality of beacons; and a user location correction unit that corrects the user's location measured by the user location measurement unit using a Bluetooth signal received from another nearby terminal.

Preferably, the user location measurement unit may further include a beacon signal correction unit that corrects the received Bluetooth signal using a Kalman filter.

Preferably, the user location correction unit may further include a terminal signal correction unit that corrects the received Bluetooth signal using a spline curve.

Preferably, the Bluetooth signals transmitted and received by the plurality of beacons or the user terminal may be Bluetooth Low Energy (BLE).

In addition, the present invention includes a receiving step of a user terminal receiving a Bluetooth signal from at least three beacons among a plurality of beacons; A user location measurement step of measuring the user's current location using the Bluetooth signal and trilateration; And another feature includes a user location correction step of correcting the user's location measured in the user location measurement step using a Bluetooth signal received from another nearby terminal.

According to the present invention, there is an advantage that the user location correction unit can use the Bluetooth signal of another terminal to correct the error in the user's primary location measured using the Bluetooth signal of the beacon and trilateration.

In addition, the present invention has the advantage of minimizing the error in the user's location by correcting the Bluetooth signal transmitted from the beacon with the beacon signal correction unit and correcting the Bluetooth signal of another terminal with the terminal signal correction unit.

Figure 1 shows a configuration diagram of an indoor position measurement system according to an embodiment of the present invention.
Figure 2 shows the value measured by the user location measurement unit according to an embodiment of the present invention for the distance between the beacon and the user terminal during the same time while changing the distance between the beacon and the user terminal at a constant rate.
Figure 3 is an example of measuring the position of a user terminal in a 2 Shows the measured results.
Figure 4 is an example of measuring the position of a user terminal in a 3 Shows the measured results.
Figure 5 shows an example of a spline interpolation multidimensional equation according to an embodiment of the present invention.
Figure 6 shows a flowchart of a method for tracking a user's location in an indoor location measurement system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the exemplary embodiments. The same reference numerals in each drawing indicate members that perform substantially the same function.

The purpose and effect of the present invention can be naturally understood or become clearer through the following description, and the purpose and effect of the present invention are not limited to the following description. Additionally, in describing the present invention, if it is determined that a detailed description of known techniques related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Figure 1 shows a configuration diagram of an indoor position measurement system 1 according to an embodiment of the present invention. Referring to FIG. 1, the indoor position measurement system 1 includes a plurality of beacons 100, a user terminal 200, a user location measurement unit 300, a beacon signal correction unit 400, and a user location correction unit 500. , may include a terminal signal correction unit 600, and DB 700.

The indoor location measurement system 1 can use a plurality of beacons 100 to determine the indoor location of a user holding the user terminal 200. The indoor location measurement system (1) can use beacons and low-power Bluetooth (BLE) to measure and utilize the user's detailed location. The indoor positioning system 1 can determine the user's approximate location using a beacon attached to a space inside a specific building. The indoor location measurement system 1 can measure a more detailed user's location by supplementing the approximate location through a Bluetooth signal between the user terminal 200 and another terminal. The indoor positioning system 1 can be used through an application installed on the user terminal 200.

A plurality of beacons 100 can transmit and receive Bluetooth signals. A plurality of beacons 100 can periodically send small packets up to 50 m without the need for pairing. Signals transmitted by a plurality of beacons 100 can be received by the user terminal 200. A plurality of beacons 100 may be fixed to a specific location indoors. The plurality of beacons 100 can distinguish specific objects to which each beacon is attached by a UUID (Universally Unique IDentifier) value. A plurality of beacons 100 can transmit signals to an individual holding the user terminal 200 without a separate pairing procedure using RSSI (Received Signal Strength Indicator).

A plurality of beacons 100 can transmit and receive Bluetooth Low Energy (BLE). The plurality of beacons 100 can use Bluetooth Low Energy (BLE) to compensate for power consumption, which was a drawback of existing Bluetooth. A plurality of beacons 100 may transmit each ID and RSSI together with a Bluetooth signal.

The user terminal 200 can transmit and receive Bluetooth signals with another terminal or a plurality of beacons 100. The user terminal 200 can transmit and receive Bluetooth Low Energy (BLE). The user terminal 200 may be equipped with Bluetooth 4.0 or higher. The user terminal 200 can use Bluetooth Low Energy (BLE) to compensate for the high power consumption, which was a disadvantage of existing Bluetooth. An application that can run the indoor position measurement system 1 may be installed on the user terminal 200.

The user's current location measured by the user location measurement unit 300 may be stored in the DB 700. The DB 700 may store information on the relative distance to other terminals measured by the user location correction unit 500.

The user location measurement unit 300 may measure the user's current location using trilateration and Bluetooth signals received by the user terminal from at least three beacons among the plurality of beacons 100. The user location measuring unit 300 can measure the distance between each beacon and the user terminal 200 from the size of the beacon ID and RSSI signal included in the Bluetooth signal. The user location measurement unit 300 may measure the location of the user terminal 200 by trilaterating the distance between each measured beacon and the user terminal 200.

Trilateration used by the user location measuring unit 300 is a method of obtaining the relative position of an object using triangular geometry, similar to triangulation. Unlike triangulation that uses the length of one side and two angles at both ends, the trilateration used by the user location measuring unit 300 uses two or more reference points and the distance between the object and each reference point to determine the location of the target. In order for the user position measurement unit 300 to accurately and uniquely determine the relative position in a two-dimensional plane using only trilateration, at least three reference points are required.

The principle of measuring the distance to the beacon of the user location measurement unit 300 is as follows. When the user terminal 200 enters the signal transmission range in which the beacon transmits the Bluetooth signal omnidirectionally within a radius equal to the Tx-Power (Transmission Power), the user location measuring unit 300 determines the RSSI of the Bluetooth signal transmitted by the beacon. It can be converted to distance using The dBm value, which is a unit of RSSI calculated by the user location measurement unit 300 during the distance measurement process, is a unit representing power in mW on a dB scale. As this value approaches 0, the signal becomes stronger, and as the negative value becomes larger, the signal becomes stronger. The signal becomes weaker.

[Equation 1]

RSSI =(-10nlog(d))+TxPower

[Equation 2]

d=10 ^{(TxPower-RSSI)/(10*n)}

When the RSSI calculated by the user location measurement unit 300 during the distance measurement process is displayed on the board, it is expressed as a dBm value through the process of [Equation 1]. The user location measurement unit 300 can calculate the dBm value by applying [Equation 2] and express it as a distance (m). In [Equation 1] and [Equation 2], which are the distance measurement formulas of the user location measurement unit 300, n refers to radio wave loss, and Tx Power represents the transmission power level.

Figure 2 shows the user location measuring unit 300 according to an embodiment of the present invention measuring the distance between the beacon and the user terminal 200 during the same time while changing the distance between the beacon and the user terminal 200 at a constant rate. Indicates the value. Referring to Figure 2, the user location measurement unit 300 can measure relatively stably with an error of less than 1m when the distance between the beacon and the user terminal 200 is 2m, but as the distance increases, severe noise is included in the measurement. It can be.

Figure 3 is an example of measuring the position of a user terminal in a 2 Shows the measured results.

Referring to Figures 3 (a) and (b), the user location measuring unit 300 is found to be in the actual location section with a probability of 85% or more when measuring with the user terminal 200 positioned at the upper and lower left sides. It can be measured.

Figure 4 is an example of measuring the position of a user terminal in a 3 Shows the measured results.

Referring to (a) of FIG. 4, the user location measurement unit 300 can be measured to be in the actual location section with a 70.1% probability when measured with the user terminal 200 placed at the upper left. Referring to (b) of FIG. 4, the user location measurement unit 300 can be measured to be in the actual location section with an 8% probability when measured with the user terminal 200 placed at the bottom left.

According to this embodiment, the user location measuring unit 300 may generate an error in measuring the location of the user terminal 200 depending on the distance between the beacon and the user terminal 200 or the size of the section to be measured. Therefore, the user location measurement unit 300 needs to measure the user's location using a corrected signal.

The beacon signal correction unit 400 can correct the Bluetooth signal received by the user location measurement unit 300 using a Kalman filter. The beacon signal correction unit 400 can use a Kalman filter, a recursive filter that tracks the state of a linear dynamical system containing noise. The beacon signal correction unit 400 can correct errors caused by the Bluetooth signal due to the surrounding environment, such as surrounding obstacles, weather, or humidity, using a Kalman filter. The beacon signal correction unit 400 can provide the corrected signal to the user location measurement unit 300, and the user location measurement unit 300 can use it to reduce errors in location measurement.

The user location correction unit 500 may correct the user's location measured by the user location measurement unit 300 using a Bluetooth signal received from another nearby terminal. The user location correction unit 500 may measure the relative position between the user terminal 200 and the other terminal using a Bluetooth signal between the user terminal 200 and the other terminal. The user location correction unit 500 can measure its own location and the location of another terminal in the same space through an estimate of the relative location with the other terminal.

The user location correction unit 500 uses the distance between the beacon and another terminal, the location of the other terminal measured using triangulation, and the relative distance between the user terminal 200 and the other terminal to determine the user location measurement unit 300. The measured position of the user terminal 200 can be corrected. The user location correction unit 500 may correct the location by performing multilateration measurement using distance measurements between the plurality of beacons 100 and other terminals. The user location correction unit 500 can effectively correct the user's location measured by the user location measurement unit 300 because the Bluetooth signal between terminals has less noise and is more reliable than a beacon signal.

[Table 1]

[Table 1] shows the Kalman filtered RSSI average value of each terminal measured by the user location correction unit 500 for a certain period of time with the distance between two terminals according to an embodiment of the present invention set at a constant ratio and [Equation 2] Indicates the distance calculated using (Tx power is fixed at -20, n=2). Referring to [Table 1], when the user location correction unit 500 fixes the receiver and the sender, the average RSSI value decreases as the actual distance increases. When the receiver and sender change, the user location correction unit 500 can measure the RSSI average value and the distance calculated using [Equation 2] to be different from the actual value even at the same distance.

[Table 2]

[Table 2] shows the average RSSI value between each terminal measured by the user location correction unit 500 by collecting Bluetooth signals from three terminals. The user location correction unit 500 can measure the average RSSI value differently when the receiver is the same and the sender is different even at the same distance. The user location correction unit 500 can measure the average RSSI value differently when the sender is the same and the receiver is different even at the same distance.

According to this embodiment, when the user location correction unit 500 calculates the distance between terminals, an error with the actual distance may occur. Therefore, the user location correction unit 500 needs to correct the Bluetooth signal received from another terminal.

The terminal signal correction unit 600 may correct the Bluetooth signal received by the user location correction unit 500 using a spline curve. The terminal signal correction unit 600 can generate a multidimensional equation using the actual distance data according to the RSSI value for each pair of receiver and sender using spline interpolation. The terminal signal correction unit 600 can generate a spline curve using the generated multidimensional equation. The terminal signal correction unit 600 can reduce the error in the distance between the user terminal 200 and other terminals measured by the user position correction unit 500 through the spline curve.

Figure 5 shows an example of a spline interpolation multidimensional equation according to an embodiment of the present invention. Referring to FIG. 5, the terminal signal correction unit 600 receives a spline curve of a multidimensional equation generated by spline interpolation using RSSI values for each distance of 3m, 5m, and 7m measured in advance. A Bluetooth signal can be corrected.

[Table 3]

[Table 3] shows the RSSI value for each distance before applying correction using a spline curve and the RSSI value calculated after correction. Referring to [Table 3], it can be seen that the error is significantly improved when corrected using a spline curve.

The terminal signal correction unit 600 can provide the corrected signal to the user location correction unit 500, and the user location correction unit 500 can use this to reduce errors in distance measurement.

Figure 6 shows a flowchart of a method for tracking a user's location in the indoor location measurement system 1 according to an embodiment of the present invention. Referring to FIG. 6, the indoor position measurement system 1 can be connected to the DB 700 through an application on the user terminal 200. The indoor location measurement system 1 can store the distance between the user terminal 200 and the plurality of beacons 100 measured in real time by the user location measurement unit 300 in the DB 700. The indoor location measurement system 1 triangulates the distance between the user terminal 200 and the plurality of beacons 100 stored in the DB 700 through the user location measurement unit 300 to determine the current location of the primary user. It can be measured. The indoor position measurement system 1 can store the distance between the user terminal 200 and other terminals measured in real time by the user position correction unit 500 in the DB 700. The indoor location measurement system 1 can convert the location by adjusting the user's location by comparing the current location of the primary user and the relative distance between the user terminal 200 and other terminals. The indoor position measurement system 1 may store the adjusted and converted, that is, corrected, user's location in the DB 700.

In another embodiment of the present invention, the indoor location measurement method may include a reception step, a user location measurement step, a beacon signal correction step, a user location correction step, and a terminal signal correction step.

In the receiving step, the user terminal may receive a Bluetooth signal from at least three beacons among a plurality of beacons.

The user location measurement step can measure the user's current location using Bluetooth signals and trilateration. The user location measurement step refers to the operation performed by the user location measurement unit described above.

In the beacon signal correction step, the Bluetooth signal received in the reception step can be corrected using a Kalman filter. The beacon signal correction step refers to the operation performed in the beacon signal correction unit described above.

In the user location correction step, the user's location measured in the user location measurement step can be corrected using a Bluetooth signal received from another nearby terminal. The user location correction step refers to the operation performed by the user location correction unit described above.

The terminal signal correction step can correct the Bluetooth signal received in the user location correction step using a spline curve. The terminal signal correction step refers to the operation performed in the terminal signal correction unit described above.

Although the present invention has been described in detail through representative embodiments above, those skilled in the art will understand that various modifications can be made to the above-described embodiments without departing from the scope of the present invention. will be. Therefore, the scope of rights of the present invention should not be limited to the described embodiments, but should be determined not only by the claims described later, but also by all changes or modified forms derived from the claims and the concept of equivalents.

1: Indoor position measurement system
100: Multiple beacons
200: user terminal
300: User location measurement unit
400: Beacon signal correction unit
500: User location correction unit
600: Terminal signal correction unit
700 : DB

Claims (5)

A plurality of beacons that transmit and receive Bluetooth signals;
A user terminal that transmits and receives Bluetooth signals with another terminal or the plurality of beacons;
a user location measuring unit that measures the current location of the user using trilateration and Bluetooth signals received by the user terminal from at least three beacons among the plurality of beacons;
a user location correction unit that corrects the user's location measured by the user location measurement unit using a Bluetooth signal received from another nearby terminal; and
A terminal signal correction unit that corrects the Bluetooth signal received by the user location correction unit from another terminal using a predetermined spline curve using RSSI (Received Signal Strength Indicator) data for each distance,
The terminal signal correction unit,
Generating a multidimensional equation using actual distance data according to RSSI values for each pair of receiver and sender, and generating the spline curve using the generated multidimensional equation,
An indoor positioning system that measures the user's position with minimal error.
According to claim 1,
An indoor location measurement system further comprising a beacon signal correction unit that corrects the Bluetooth signal received by the user location measurement unit using a Kalman filter.
delete According to claim 1,
An indoor location measurement system, wherein the Bluetooth signals transmitted and received by the plurality of beacons or the user terminal are Bluetooth Low Energy (BLE).
A receiving step in which the user terminal receives a Bluetooth signal from at least three beacons among a plurality of beacons;
A user location measurement step of measuring the user's current location using the Bluetooth signal and trilateration;
A user location correction step of correcting the user's location measured in the user location measurement step using a Bluetooth signal received from another nearby terminal; and
A terminal signal correction step of correcting the Bluetooth signal received from another terminal in the user location correction step using a predetermined spline curve using RSSI (Received Signal Strength Indicator) data for each distance,
The terminal signal correction step is,
Generating a multidimensional equation using actual distance data according to RSSI values for each pair of receiver and sender; and
Including, generating the spline curve using the generated multidimensional equation.
An indoor position measurement method that minimizes the error of the user's position indoors.