KR20220108685A - System for tracking location using access point and imu and method thereof - Google Patents

Abstract

The present invention relates to a system for tracking a location using an access point (AP) and an inertial measuring unit (IMU), and a method thereof. The method for tracking a location using the system for tracking a location using the AP and the IMU comprises the steps of: allowing a user terminal to acquire a distance range between the user terminal and an AP from the AP installed in the vicinity thereof; sensing data through an IMU installed in the user terminal; acquiring converted data by converting the sensed data by a global coordinate system; determining a user's walking status using the converted data; if it is determined that the user is walking, estimating the user's stride width using the converted data; estimating the user's direction using the converted data; applying the converted data and the user's stride width to the pedestrian dead reckoning (PDR) technique to estimate the user's location; and determining the user's estimated location as the current location if the distance between the estimated current location of the user and the AP, obtained through the coordinates, is within the distance range between the user terminal and the AP. The system and the method for tracking a location using the AP and the IMU are provided to accurately track the location of an iOS-based user terminal.

Description

Location tracking system and method using AP and IMU

The present invention relates to a location tracking system and method using an AP and an IMU, and to a location tracking system and a method using an AP and an IMU for accurately tracking the location of an iOS-based user terminal.

The indoor positioning method using an existing smartphone receives an indoor map from a smartphone through a Wi-Fi AP (Access Point) installed indoors, and then uses the RSS (Received Signal Strength) value provided from the Wi-Fi AP. A method of tracking the user's location was used.

However, there is a problem in that the RSS value cannot be received from the Wi-Fi AP due to a change in the Wi-Fi information provision policy caused by Apple's iOS 13 update in September 2019.

Therefore, in the indoor environment of iPhone users, a method for calculating the user's current location through the inertial measurement unit (IMU) installed in the smartphone is needed for the user location positioning technology through the Wi-Fi AP.

The technology that is the background of the present invention is disclosed in Korean Patent No. 10-1600561 (2016.03.07. Announcement).

An object of the present invention is to provide a location tracking system and method using an AP and an IMU for accurately tracking the location of an iOS-based user terminal.

According to an embodiment of the present invention for achieving this technical problem, in a location tracking method using a location tracking system using an AP and an IMU, a distance between a user terminal and an AP through short-range communication with an AP (access point) installed nearby Acquiring a range, sensing data through an inertial measurement unit (IMU) installed in the user terminal, converting the sensed data into a global coordinate system to obtain converted data, using the converted data to the user determining whether to walk, if it is determined that the user is walking, estimating the stride length of the user using the converted data, estimating the direction of the user using the converted data, the converted data and estimating the user's location by applying the user's stride length to a Pedestrian Dead Reckoning (PDR) technique, and a distance obtained through coordinates between the estimated current location of the user and the AP is determined by the user. and determining the estimated user's location as the current location when it is included within the distance range between the terminal and the AP.

The obtaining of the distance range between the user terminal and the AP includes obtaining a distance range between the user terminal and the AP using a received signal strength (RSSI) of the AP, but in the distance range between the user terminal and the AP Accordingly, it can be divided into an immediate state, a near state, a far state, and an unknown state.

If the estimated distance obtained through the coordinates for the current location of the user and the coordinates between the AP is not included within the distance range between the user terminal and the AP, correcting the user's location based on the RSSI value; may include more.

In the step of correcting the user's location based on the RSSI value, if the distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is shorter than the distance range between the user terminal and the AP, By extending a virtual straight line connecting the user terminal and the AP, a point intersecting the inner circle corresponding to the corresponding distance range of the AP may be determined as the current location of the user.

In the step of correcting the user's location based on the RSSI value, if the distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is longer than the distance range between the user terminal and the AP, A point intersecting a straight line between the user terminal and the AP and an outer circle corresponding to the corresponding distance range of the AP may be determined as the current location of the user.

) 이상인 경우, 상기 사용자가 보행하는 것으로 판단할 수 있다.In the step of determining whether the user is walking, the acceleration value measured from the inertia measurement device is a threshold value (

) or more, it may be determined that the user is walking.

The estimating of the user's stride length may include estimating the user's stride length by applying the converted data to the following equation.

는 상기 사용자의 보폭이고,

는 최대 가속도 값,

은 최소 가속도 값,

는 보정상수이다.here,

is the stride length of the user,

is the maximum acceleration value,

is the minimum acceleration value,

is the correction constant.

In the estimating of the user's location, the user's location may be estimated using the following equation.

및

는 상기 사용자의 초기 위치이고,

및

는 k번째로 이동한 상기 사용자의 위치이고,

은 상기 사용자의 보폭,

은 상기 사용자의 방향성이다.here,

and

is the initial location of the user,

and

is the location of the user who moved to the k-th,

is the user's stride length,

is the direction of the user.

The inertial measurement device may include a gyro sensor, an acceleration sensor, a geomagnetic sensor, and a compass sensor.

The user terminal may be based on an iOS operating system.

The nearby state represents a case in which the user terminal exists within a first reference distance from the AP, and the near state represents a case in which the user terminal exists at a distance greater than the first reference distance and less than a second reference distance from the AP. The remote state indicates a case in which the user terminal is present at a distance greater than a second reference distance and less than a third reference distance from the AP, and the unconfirmed state is the user terminal at a distance greater than or equal to a third reference distance from the AP. may indicate the presence of

According to another embodiment of the present invention, in a location tracking system using an AP and an IMU, a communication unit for obtaining a distance range between a user terminal and an AP through short-range communication with an AP (access point) installed in the vicinity, the user terminal A data sensing unit that senses data through an installed inertial measurement unit (IMU), a transformation data acquisition unit that converts the sensed data into a global coordinate system to obtain transformation data, and determines whether the user walks by using the transformation data and, when it is determined that the user is walking, a position estimator for estimating the user's stride and the direction of the user using the converted data, and a Pedestrian Dead Reckoning (PDR) technique for the converted data and the user's stride a location estimator for estimating the user's location by applying to, and a distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is included in the distance range between the user terminal and the AP. and a control unit that determines the estimated user's location as the current location.

As described above, according to the present invention, when the starting position is determined through the minimum Wi-Fi AP deployed without the need for additional installation of the Wi-Fi AP used in the existing indoor positioning technique, the user can use the IMU sensor of the smartphone. location can be estimated.

In addition, effective location estimation may be possible in a situation where external communication is difficult, such as in a disaster environment.

1 is a configuration diagram for explaining the configuration of a location tracking system according to an embodiment of the present invention.
2 is a flowchart illustrating a location tracking method according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining step S210 of FIG. 2 .
FIG. 4 is a diagram for explaining step S240 of FIG. 2 .
FIG. 5 is a diagram for explaining step S280 of FIG. 2 .
6A and 6B are diagrams for explaining step S290 of FIG. 2 .
7 is a block diagram illustrating a location tracking method according to an embodiment of the present invention.
8 is a diagram illustrating a result of tracking a location indoors using a location tracking system according to an embodiment of the present invention.
9 is a view showing the accuracy in the case of using only the location tracking system and the existing PDR technique according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Then, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them.

1 is a configuration diagram for explaining the configuration of a location tracking system according to an embodiment of the present invention.

As shown in FIG. 1 , the location tracking system 100 according to an embodiment of the present invention includes a communication unit 110 , a data sensing unit 120 , a converted data obtaining unit 130 , a direction estimation unit 140 , and a location estimation unit. 150 and a control unit 160 .

First, the communication unit 110 obtains a distance range between the user terminal and the AP.

At this time, the communication unit 110 acquires the distance range between the user terminal and the AP by using the RSSI of the AP, but according to the distance range between the user terminal and the AP, an immediate state, a near state (near) ), the far state and the unknown state.

In addition, the nearby state indicates a case in which the user terminal is present within a first reference distance from the AP, and the near state indicates a case in which the user terminal is present at a distance greater than the first reference distance and smaller than the second reference distance from the AP, The state indicates a case in which the user terminal is present at a distance greater than the second reference distance from the AP and less than the third reference distance, and the unverifiable state indicates a case in which the user terminal is present at a distance greater than or equal to the third reference distance from the AP.

In this case, the first to third reference distances may be set to 5 m, 10 m, and 15 m, respectively, and may vary according to the setting of the location tracking system 100 .

In addition, the received signal strength (RSSI) refers to the signal power received by the wireless receiver, and is used to measure the distance range between the AP and the user terminal in the embodiment of the present invention.

Here, the user terminal is a portable user terminal, implemented as a device capable of exchanging information by connecting to a network by wire or wireless such as a notebook computer, a smart pad, or a smart phone, and means a terminal driven by the iOS operating system.

Also, an AP (Access Point) is a device that supports a wireless device to connect to another wired device through a network, and in the embodiment of the present invention, it means a Wi-Fi device.

Next, the data sensing unit 120 senses data through an inertial measurement unit (IMU) installed in the user terminal.

Here, the inertial measurement unit (IMU) is a device for measuring a specific force, an angular ratio of the body, and sometimes a magnetic field surrounding the body using an acceleration sensor, a rotation sensor, and a magnetic force sensor, and is installed in a user terminal in the embodiment of the present invention to sense each data.

Next, the transform data acquisition unit 130 converts the sensed data into a global coordinate system to obtain transform data.

Here, the global coordinate system is a coordinate system representing latitude, longitude, and height based on a prime meridian, and the present invention converts the sensed local coordinate system into a global coordinate system and uses it.

Next, the direction estimator 140 determines whether the user walks using the converted data, and when it is determined that the user is walking, estimates the user's stride length using the converted data.

Then, the position estimator 150 estimates the position of the user by applying the direction and the stride length of the user to the Pedestrian Dead Reckoning (PDR) technique using the converted data.

Here, the PDR technique is an algorithm for calculating the relative position from the starting point by grasping movement information such as the speed, acceleration, direction and distance at which a person moves using a plurality of sensors, and in the embodiment of the present invention, the user's position used to estimate

Next, the controller 160 determines whether a distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is included in the distance range between the user terminal and the AP.

At this time, if the estimated distance obtained through the coordinates for the current location of the user and the coordinates between the AP is not included in the distance range between the user terminal and the AP, the controller 160 determines the location of the user based on the RSSI value. Correct.

That is, if the distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is shorter than the range of the distance between the user terminal and the AP, the controller 160 controls a virtual connection between the user terminal and the AP. By extending the straight line of the AP, a point intersecting the inner circle corresponding to the corresponding distance range of the AP is determined as the current location of the user.

Hereinafter, a location tracking method according to an embodiment of the present invention will be described with reference to FIGS. 2 to 7 .

2 is a flowchart illustrating a location tracking method according to an embodiment of the present invention.

First, the communication unit 110 obtains a distance range between the user terminal and the AP (S210).

In this case, the distance range between the user terminal and the AP means a nearby state, a near state, a remote state, and an unverifiable state.

FIG. 3 is a diagram for explaining step S210 of FIG. 2 .

As shown in FIG. 3 , the distance range between the APs means a range in which the first to third reference distances are radii with respect to the AP.

In this case, the communication unit 110 sets the case where the user terminal exists within the first reference distance from the AP as a nearby state, and sets the case where the user terminal exists at a distance greater than the first reference distance from the AP and less than the second reference distance as the short-range state. set to state

In addition, the communication unit 110 sets the case in which the user terminal is present at a distance greater than the second reference distance and less than the third reference distance from the AP as the remote state, and when the user terminal is present at a distance greater than or equal to the third reference distance from the AP. is set to unverifiable.

Next, the data sensing unit 120 senses data through an inertial measurement unit (IMU) attached to the user terminal ( S220 ).

That is, the data sensing unit 120 senses data on the acceleration, the rotation radius, and the moving direction of the user's movement through the inertia measurement device.

Next, the transform data acquisition unit 130 converts the sensed data into a global coordinate system to obtain transform data (S230).

In this case, the transformed data acquisition unit 130 pre-processes the sensed data by applying the sensed data to the low-pass filter, and converts the pre-processed data into a global coordinate system to obtain transformed data.

Next, the direction estimator 140 determines whether the current user is walking ( S240 ).

FIG. 4 is a diagram for explaining step S240 of FIG. 2 .

)이상인 상태에서 최대 가속도 값(A_max)에 도달한뒤 임계 값보다 작은 값을 가지는 경우, 사용자가 보행하는 것으로 판단한다.That is, as shown in FIG. 4 , the direction estimator 140 determines that the 3-axis acceleration value measured from the inertial measurement device is the threshold value (

) or higher, when it reaches the maximum acceleration value (A_max) and has a value smaller than the threshold value, it is determined that the user is walking.

Here, when the user is not walking, the direction estimator 140 continuously determines whether the user is walking.

On the other hand, when the user is walking, the direction estimator 140 estimates the user's stride length and direction using the converted data (S250).

That is, the direction estimator 140 estimates the user's stride length by applying the transformed data to Equation 1 below.

는 상기 사용자의 보폭이고,

는 최대 가속도 값,

은 최소 가속도 값,

는 보정상수이다.here,

is the stride length of the user,

is the maximum acceleration value,

is the minimum acceleration value,

is the correction constant.

Next, the location estimator 150 estimates the location of the user by applying the converted data and the user's stride to the PDR technique ( S260 ).

That is, the location estimator 150 estimates the user's location using Equation 2 below.

및

는 사용자의 초기 위치이고,

및

는 k번째로 이동한 사용자의 위치이고,

은 사용자의 보폭,

은 사용자의 방향성이다.here,

and

is the user's initial location,

and

is the location of the user who moved to the kth,

is the user's stride length,

is the user's direction.

)은 관성측정장치을 통해 측정된 데이터를 iOS의 CoreLocation 라이브러리로부터 제공되는 CLHeading 클래스를 통해 연산된다.Here, the user's direction (

) is calculated through the CLHeading class provided from the CoreLocation library of iOS on the data measured through the inertial measurement device.

Next, the controller 160 determines whether a distance obtained through the estimated coordinates for the current location of the user and the coordinates between the AP is included in the range of the distance between the user terminal and the AP (S270).

That is, it is determined where the estimated coordinates for the current location of the user are located among the nearby state, the near state, the remote state, or the unconfirmable state.

Next, if the acquired distance is included in the distance range between the user terminal and the AP, the controller 160 determines the estimated user's location as the current location (S280).

FIG. 5 is a diagram for explaining step S280 of FIG. 2 .

For example, as shown in FIG. 5 , when the estimated user's current location is in a short distance from the AP, the controller 160 determines the estimated user's location as the current location.

On the other hand, if the acquired distance is not included in the distance range between the user terminal and the AP, the controller 160 corrects the estimated user's location based on the RSSI value (S290).

6A and 6B are diagrams for explaining step S290 of FIG. 2 .

For example, as shown in FIG. 6A , when the estimated user's current location is outside the second reference distance, the controller 160 connects the estimated user's current location and the AP with a virtual straight line, and the corresponding distance range A point that intersects the outer circle corresponding to .

As another example, as shown in FIG. 6B , when the estimated user's current location is within the first reference distance, the controller 160 connects the estimated user's current location and the AP with a virtual straight line, A point intersecting the inner circle corresponding to the distance range is corrected as the user's current location.

7 is a block diagram illustrating a location tracking method according to an embodiment of the present invention.

That is, as shown in FIG. 7 , the location tracking method according to an embodiment of the present invention tracks the location of the corresponding user terminal by using the Wi-Fi signal of the iOS-based user terminal and a plurality of data sensed from the inertial measurement device. .

8 is a view showing a result of tracking a location indoors using a location tracking system according to an embodiment of the present invention, and FIG. 9 is a case where only the location tracking system according to an embodiment of the present invention and the existing PDR technique are used A diagram showing the accuracy of

As shown in FIG. 8 , the blue line is the user's location tracked through the location tracking system according to the embodiment of the present invention, and it can be confirmed that the tracked location is corrected to the actual moved location by using the AP signal.

In addition, as shown in FIG. 9 , it can be confirmed that the result of estimating the location using the location tracking system according to the embodiment of the present invention reduces the error by 20% to 30% compared to when only the conventional PDR technique is used. .

As described above, according to an embodiment of the present invention, if the starting position is determined through the minimum Wi-Fi AP that has been previously deployed without the need for additional installation of the Wi-Fi AP used in the existing indoor positioning technique, the IMU sensor of the smartphone can estimate the user's location.

In addition, effective location estimation may be possible in a situation where external communication is difficult, such as in a disaster environment.

Although the present invention has been described with reference to the embodiment shown in the drawings, which is merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: location tracking system, 110: communication unit,
120: data sensing unit, 130: converted data acquisition unit,
140: a direction estimator, 150: a position estimator,
160: control unit

Claims (18)

In a location tracking method using a location tracking system using an AP and an IMU,
acquiring a distance range between the user terminal and the AP through short-distance communication with an AP (access point) installed in the vicinity;
Sensing data through an inertial measurement unit (IMU) installed in the user terminal;
converting the sensed data into a global coordinate system to obtain transformed data;
determining whether the user walks using the converted data;
estimating the stride length of the user using the converted data when it is determined that the user is walking;
estimating the direction of the user using the converted data;
estimating the location of the user by applying the converted data and the user's stride to a Pedestrian Dead Reckoning (PDR) technique; and
determining the estimated user's location as the current location when the distance obtained through the coordinates between the estimated user's current location and the AP is within a distance range between the user terminal and the AP location tracking method. According to claim 1,
The step of obtaining a distance range between the user terminal and the AP comprises:
Obtaining a distance range between the user terminal and the AP using the received signal strength (RSSI) of the AP,
A location tracking method divided into an immediate state, a near state, a far state, and an unknown state according to a distance range between the user terminal and the AP. According to claim 1,
If the estimated distance obtained through the coordinates for the current location of the user and the coordinates between the AP is not included in the distance range between the user terminal and the AP, correcting the location of the user based on the RSSI value; More including location tracking methods. 4. The method of claim 3,
The step of correcting the user's location based on the RSSI value comprises:
If the distance obtained through the coordinates between the estimated coordinates for the current location of the user and the AP is shorter than the range of the distance between the user terminal and the AP,
A location tracking method for extending a virtual straight line connecting the user terminal and the AP to determine a point that intersects an inner circle corresponding to the corresponding distance range of the AP as the current location of the user. 4. The method of claim 3,
The step of correcting the user's location based on the RSSI value comprises:
If the distance obtained through the coordinates between the estimated coordinates for the current location of the user and the AP is longer than the distance range between the user terminal and the AP,
A location tracking method for determining a point where a straight line connecting the user terminal and the AP and an outer circle corresponding to the corresponding distance range of the AP intersect as the current location of the user. 3. The method of claim 2,
The step of determining whether the user walks,
The acceleration value measured from the inertial measurement device is a threshold value (

) or more, the location tracking method for determining that the user is walking. 7. The method of claim 6,
The step of estimating the user's stride length,
A location tracking method for estimating the user's stride length by applying the converted data to the following equation:

here,

is the stride length of the user,

is the maximum acceleration value,

is the minimum acceleration value,

is the correction constant. 8. The method of claim 7,
The step of estimating the location of the user,
A location tracking method for estimating the location of the user using the following equation:

here,

and

is the initial location of the user,

and

is the location of the user who moved to the k-th,

is the user's stride length,

is the direction of the user. According to claim 1,
The inertial measurement device,
Position tracking method including gyro sensor, accelerometer sensor, geomagnetic sensor and compass sensor. According to claim 1,
The user terminal is
A location tracking method based on the iOS operating system. 3. The method of claim 2,
The neighboring state indicates a case in which the user terminal exists within a first reference distance from the AP,
The short-range state represents a case in which the user terminal is present at a distance greater than a first reference distance and less than a second reference distance from the AP,
The remote state indicates a case in which the user terminal is present at a distance greater than a second reference distance and less than a third reference distance from the AP,
The unverifiable state is a location tracking method indicating a case in which the user terminal is present at a distance greater than or equal to a third reference distance from the AP. In the location tracking system using AP and IMU,
A communication unit that acquires a distance range between the user terminal and the AP through short-range communication with an AP (access point) installed in the vicinity;
A data sensing unit for sensing data through an inertial measurement unit (IMU) installed in the user terminal;
a transformation data acquisition unit that converts the sensed data into a global coordinate system to obtain transformation data;
a direction estimator for estimating the user's stride length and the direction of the user by using the converted data to determine whether the user walks by using the converted data, and when it is determined that the user is walking;
a position estimator for estimating the position of the user by applying the converted data and the stride length of the user to a Pedestrian Dead Reckoning (PDR) technique; and
and a controller configured to determine the estimated user's location as the current location when the distance obtained through the coordinates between the estimated user's current location and the AP is within a distance range between the user terminal and the AP. location tracking system. 13. The method of claim 12,
The communication unit,
A distance range between the user terminal and the AP is obtained using the received signal strength (RSSI) of the AP, and depending on the distance range between the user terminal and the AP, an immediate state, a near state, and a far state A location tracking system that distinguishes between (far) and unknown (unknown). 13. The method of claim 12,
The control unit is
If the estimated distance obtained through the coordinates for the current location of the user and the coordinates between the AP is not included in the distance range between the user terminal and the AP, the location tracking for correcting the location of the user based on the RSSI value system. 15. The method of claim 14,
The control unit is
If the distance obtained through the coordinates between the estimated coordinates for the current location of the user and the AP is shorter than the range of the distance between the user terminal and the AP,
A location tracking system for extending a virtual straight line connecting the user terminal and the AP to determine a point that intersects the inner circle corresponding to the corresponding distance range of the AP as the current location of the user. 15. The method of claim 14,
The control unit is
If the distance obtained through the coordinates between the estimated coordinates for the current location of the user and the AP is longer than the distance range between the user terminal and the AP,
A location tracking system for determining a point where a straight line connecting the user terminal and the AP and an outer circle corresponding to the corresponding distance range of the AP intersect as the current location of the user. 13. The method of claim 12,
The user terminal is
A location tracking system based on the iOS operating system. 14. The method of claim 13,
The neighboring state indicates a case in which the user terminal exists within a first reference distance from the AP,
The short-range state represents a case in which the user terminal is present at a distance greater than a first reference distance and less than a second reference distance from the AP,
The remote state indicates a case in which the user terminal is present at a distance greater than a second reference distance and less than a third reference distance from the AP,
The unconfirmable state is a location tracking improvement system indicating a case in which the user terminal is located at a distance greater than or equal to a third reference distance from the AP.

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