KR20120006306A - Indoor location measuring device and method - Google Patents

Abstract

The present invention relates to an indoor position measuring apparatus and method using light emitting diode illumination to which visible light communication is applied, comprising: a light emitting diode illumination (10) receiving a plurality of modulated light emitting diode position signals and converting the light signal into an optical signal; Dual image sensors 20 and 30 installed to be spaced apart from the light emitting diode illumination 10 to convert an optical signal into an electrical signal and output the electrical signal; Receives and modulates the electrical signals output from the dual image sensors 20 and 30 to obtain position information of the plurality of light emitting diodes 11 and uses the obtained position information of the plurality of light emitting diodes 11 to target positions. By configuring the controller 40 to calculate the coordinates of the, characterized in that to improve the measurement accuracy by preventing the measurement error caused by the interference of the external signal.

Description

Indoor location measuring device and method {INDOOR POSITIONING APPARATUS AND METHOD}

The present invention relates to an indoor position measuring apparatus and method, and more particularly, to an indoor position measuring apparatus and method using light emitting diode illumination to which visible light communication is applied.

Korean Unexamined Patent Publication No. 2010-0021325 discloses a process and method for enabling satellite signals to be received in a shaded area such as a tunnel and indoors where a GPS signal is not input, to confirm a location, and to provide a navigation service.

However, in this prior art, GPS has a problem that a large position error occurs due to radio wave transmission, multipath disappearance and crosstalk from other radio sources in an indoor environment.

In addition, conventional indoor positioning devices such as WLAN, RFID, Bluetooth, and Ultrasound also include problems due to system instability, long response time, and low accuracy and precision.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide an indoor position measuring apparatus and method using a light emitting diode illumination and a dual image sensor to which visible light communication (VLC) is applied.

Another object of the present invention is to measure the indoor position using the light signal emitted and irradiated from the light emitting diode illumination to which visible light communication is applied to prevent the measurement error due to the interference of the external signal indoor position measurement that can improve the measurement accuracy An apparatus and method are provided.

An indoor position measuring apparatus of the present invention includes: a light emitting diode illumination receiving a plurality of modulated light emitting diode position signals and converting the light signal into an optical signal; A dual image sensor installed to be spaced apart from the light emitting diode illumination to receive an optical signal and convert the light signal into an electrical signal; And receiving and modulating the electrical signals output from the dual image sensors, thereby obtaining position information of a plurality of light emitting diodes, and calculating a coordinate of a target position using the obtained position information of the plurality of light emitting diodes. It features.

Indoor positioning method of the present invention comprises the steps of storing the distance between the focal length and the optical lens of the optical lens provided in each of the dual image sensor; Demodulating electrical signals according to the modulated plurality of light emitting diode position signals and storing position information of the plurality of light emitting diodes; Calculating and storing distance information between a plurality of light emitting diodes and a target position using a distance between a focal length of the dual image sensor and an optical lens provided in each of the dual image sensors; And calculating coordinates of a target location using location information of the plurality of light emitting diodes and distance information between the plurality of light emitting diodes and a target location, wherein the coordinates of the target location connect the centers of the plurality of optical lenses. It is characterized in that the intermediate position of the straight line.

Indoor positioning apparatus and method of the present invention can improve the measurement accuracy by preventing the measurement error due to interference of the external signal by measuring the indoor position by using the light signal emitted and irradiated from the light emitting diode illumination to which visible light communication is applied There is an advantage to that.

1 is a view showing the configuration of an indoor position measuring apparatus of the present invention,
2 is a view showing the indoor position measuring method of the present invention,
3A and 3B show the range of the measurement area, respectively;
4 is a graph showing a position error using the least squares estimation method of the indoor position measurement method of the present invention,
5 is a graph showing a position error using a vector estimation method of the indoor position measurement method of the present invention,
6 is a graph showing the position error obtained by using the least-squares estimation and the vector estimation method of the indoor position measurement method of the present invention,
FIG. 7A is a graph showing RMS position errors of the least square estimation method and the vector estimation method according to the distance between lenses in the indoor position measuring method of the present invention; FIG.
7b is a graph comparing the RMS error of the least square estimation method and the vector estimation method in a graph of the quadratic exponential function in the indoor position measuring method of the present invention;
8 is a table showing a list of simulation parameters of the indoor position measuring method of the present invention,
9 is a table comparing the indoor positioning method of the present invention and the conventional visible light communication based position measuring method.

Hereinafter, an embodiment of an indoor position measuring apparatus and method of the present invention will be described with reference to the accompanying drawings.

1 and 2, the indoor positioning apparatus of the present invention includes a light emitting diode illumination 10, dual image sensors 20 and 30, and a controller 40. As shown in FIG.

The light emitting diode illumination 10 receives a plurality of modulated light emitting diode position signals, converts them into optical signals, and irradiates them. The dual image sensors 20 and 30 are respectively installed to be spaced apart from the light emitting diode illumination 10 to provide an optical signal. It is irradiated and converted into an electrical signal and output. The controller 40 receives and modulates electric signals output from the dual image sensors 20 and 30, respectively, to obtain position information of the plurality of light emitting diodes 11, and obtains position information of the obtained plurality of light emitting diodes 11. Calculate the coordinates (x, y, z) of the target position (U) using.

Hereinafter, the indoor position measuring apparatus of the present invention having the above configuration will be described in detail.

The light emitting diode illumination 10 receives four light emitting diode position signals modulated as shown in FIG. 1, converts each of them into an optical signal, and irradiates the light emitting diode position signals. The plurality of light emitting diode position signals are respectively provided in the light emitting diode illumination 10. The installation positions A, B, C, and D of the plurality of light emitting diodes 11 are shown. The light emitting diode lighting 10 is fixedly installed in a room, and a plurality of light emitting diodes 11 are arranged in a horizontal and vertical direction, respectively. The light emitting diode illumination 10 is also used as an illumination source and is used for visible light communication (VLC).

The modulated plurality of light emitting diode position signals including information such as the installation positions A, B, C, and D of the plurality of light emitting diodes 11 are modulated by a central controller (not shown). The central controller controls the overall communication of a building (not shown) or controls the blinking of the plurality of light emitting diode lights 10 installed in the building (not shown), and measures indoor positions by modulating a plurality of light emitting diode position signals. To the light emitting diode illumination 10 as a reference.

The dual image sensors 20 and 30 are positioned to be spaced apart from each other on the same plane as in FIG. 1 and FIG. The optical lenses 21 and 31 respectively transmit and receive an optical signal emitted from the light emitting diode illumination 10, and the image elements 22 and 32 are respectively provided below the optical lenses 21 and 31, thereby providing an optical lens ( 21,31) and receives the optical signal transmitted through the electrical signal is converted into an output.

An image pickup device or a plurality of photodiodes are used as the image devices 22 and 32 that receive an optical signal and convert the light signal into an electric signal. When using a plurality of photodiodes as the image elements 22 and 32, each is used as one pixel.

The controller 40 calculates the intermediate position of the straight line L connecting the centers of the plurality of optical lenses 21 and 31 as coordinates (x, y, z) of the target position U. The controller 40, which calculates the coordinates (x, y, z) of the target position U, is an input device such as a memory (not shown) or a keyboard for storing or inputting the distance information f, L, etc., which are known in advance. (Not shown) is provided.

The indoor position measuring method using the indoor position measuring apparatus of the present invention having the above configuration is as follows.

First, the controller 40 stores the focal length f of the optical lenses 21 and 31 and the distance L between the optical lenses provided in the dual image sensors 20 and 30 shown in FIG. 2, respectively. When the focal length f of the optical lenses 21 and 31 and the distance L between the optical lenses are stored, the controller 40 demodulates an electrical signal according to the modulated plurality of light emitting diode position signals, thereby demonstrating a plurality of light emitting diodes ( 11) the position information (A, B, C, D) is stored.

The position information A, B, C, and D of the plurality of light emitting diodes 11 are disposed at corners of the light emitting diode illumination 10, respectively, as shown in FIG. 1 to position the four light emitting diodes 11 sufficiently spaced from each other. It is information and stored in a separate point-and-point controller (not shown) in the central controller (not shown) or the light emitting diode light (10) to measure in advance to control the blinking of the light emitting diode light (10).

When the position information A, B, C, and D of the plurality of light emitting diodes 11 are stored, the controller 40 may control the focal length f of the dual image sensors 20 and 30 and the dual image sensors 20 and 30. The distance information between the plurality of light emitting diodes 11 and the target position U is calculated and stored by using the distance L between the optical lenses 21 and 31 provided in the respective lenses.

When the distance information between the plurality of light emitting diodes 11 and the target position U is stored, the controller 40 may determine the position information A, B, C, and D of the plurality of light emitting diodes 11 and the plurality of light emitting diodes ( 11) and the coordinates (x, y, z) of the target position (U) are calculated using the distance information (d ₁ , d ₂ , d ₃ , d ₄ ) between the target position (U). Here, the coordinates (x, y, z) of the target position (U) is the intermediate position of the straight line L connecting the centers of the plurality of optical lenses (21, 31), by measuring the intermediate position of the present invention The center of the indoor position measuring device can be selected as the measuring position and measured.

When explaining the indoor position measuring method of the present invention having such a configuration in more detail as follows.

When selecting a plurality of light emitting diodes 11 used in the indoor position measuring method of the present invention, the same information is arranged in the light emitting diode illumination 10, rather than the same lines as shown in FIG. Choose to have D). That is, the light emitting diodes 11 installed at the corners of the light emitting diode illumination 10 are selected and used, and each of the three-dimensional coordinate information A (x1, y1, z1) and B (x2, y2, z2), C (x3, y3, z3) and D (x4, y4, z4).

When position information A (x1, y1, z1), B (x2, y2, z2), C (x3, y3, z3) and D (x4, y4, z4) having three-dimensional coordinate information are converted into an optical signal, When irradiated by the dual image sensors 20 and 30 and converted into an electrical signal and outputted, the received signal is received by the controller 40 to three-dimensional axis information of the light emitting diode 11, that is, the position information A, B, C and D. Demodulate and store. The dual image sensors 20 and 30 receive optical signals modulated by light intensity from four light emitting diodes 11 spaced apart from each other using two separate optical lenses 21 and 31 and convert them into electrical signals. To print. These dual image sensors 20 and 30 are mounted on the same surface at lateral distances known as the main axis on the same line pp '. Optical lenses 21 and 31 having the same characteristics and focal lengths are provided above the centers of the respective image sensors 20 and 30.

It will be appreciated that the method of measuring the coordinates (x, y, z) of the target position U using the position information A, B, C and D will be sufficiently calculated from FIG. "U" shown in FIG. 1 represents the intermediate position of the straight line L connecting the centers of the two optical lenses 21 and 31. The unknown three-dimensional coordinates of U (x, y, z), which are the coordinates (x, y, z) of the target position U, are measured from this system. The distance information d1, d2, d3 and d4 are respectively represented between the four light emitting diodes 11 having the positional information A, B, C and D and the target position U, respectively. , d2, d3, and d4 are calculated from the geometrical relationship due to the difference in the light emitting diode images accommodated on the two image sensors 20,30, respectively.

The geometric relationship of the position structure proposed in the indoor position measuring method of the present invention is shown in detail in FIG. 2 shows distance information d1, d2, d3, and d4 from the light emitting element 11 to the target position U through Equations 1 to 8 below.

In Equations 1 to 8, d _i is a distance between the light emitting diode 11 and the coordinates (x, yz) of the target position U, _i of d i is 1 to 4, i ₁ and i ₂ are respectively The distance from the center of the image elements 22 and 32 of the dual image sensors 20 and 30 to the center of the optical signal image, and Pi ₁ and Pi ₂ are i ₁ and the main axes of the image elements 22 and 32, respectively. i ₂ is the projected distance, f is the focal length of the optical lens (21, 31) provided in the dual image sensor (20, 30), respectively, L is an optical lens provided in the dual image sensor (20, 30), respectively The distance between 21 and 31 is shown.

When the distance information (d1, d2, d3 and d4) is calculated, the controller 40 determines the distance information (d1, d2, d3 and d4) and the plurality of light emitting diodes (reference) in the light emitting diode illumination (10). 11) position information A, B, C, D, that is, three-dimensional coordinate information A (x1, y1, z1), B (x2, y2, z2), C (x3, y3, z3) and D ( x4, y4, z4) can be used to construct four quadratic equations as shown in Equations 9 to 12, and solve the four quadratic equations to coordinate (x, y, z) of the target position (U). Will yield.

In Equations 9 to 12, (x, y, z) is the coordinate of the target position U, (x ₁ , y ₁ , z ₁ ), (x ₂ , y ₂ , z ₂ ), (x ₃ , y ₃ , z ₃ ) and (x ₄ , y ₄ , z ₄ ) represent the coordinates of the installation positions of the plurality of light emitting diodes 11, respectively, and d ₁ , d ₂ , d ₃ , and d ₄ each represent a plurality of positions. Distance information between the light emitting diodes 11 and the coordinates (x, y, z) of the target position U is shown.

The method of correcting the error of the coordinates (x, y, z) of the target position U calculated using the indoor position measuring method of the present invention will be described with reference to FIGS. 1 and 2 as follows.

The method of correcting the error of the coordinates (x, y, z) of the target position (U) is first corrected by using Least Square Estimation (LSE). The correction is performed by using vector estimation.

First, when the coordinates (x, y, z) of the target position U is calculated, the correction is performed by the least squares estimation method.

In order to estimate the three-dimensional unknown position, that is, the coordinates (x, y, z) of the target position (U), between the light emitting diodes 11 and the coordinates (x, y, z) of the target position (U). If the distance is estimated correctly, three of the four quadratic equations are sufficient. However, due to the influence of the quantization error in the pixels of the dual image sensors 20 and 30, the exact distance between the light emitting diode 11 and the coordinates (x, y, z) of the target position U cannot be estimated.

An intuitive solution to this problem is to use more of the following three light emitting diodes 11. Mathematically, when converting an equation using three light emitting diodes 11 into an over-determined system equation, this becomes a problem of linear least squares. Therefore, by solving the equations described in the following equations (13) to (16) for X, the position of the coordinates (x, y, z) of the target position (U) is estimated and corrected.

here,

And

The condition for the solution of the linear least squares estimation method using Equations 13 to 16 above is that the matrix M must have a full rank. However, a plurality of light emitting diodes 11, each of which has position information A, B, C, and D, which are reference in the light emitting diode illumination 10, respectively, are on the same plane (that is, all have the same z-coordinate value). Therefore, these conditions are not satisfied. Therefore, it is necessary to add a small value to the z-axis value of the light emitting diode 11 having the fourth criterion, that is, the position information D. This method solves the unusual problem of the matrix M or yields an errored z-axis estimate. Vector estimation is used to estimate the z-axis value, and the light emitting diode 11 having three criteria, namely, location information A, B, and C, is used for this estimation.

,

및

가 각기 A, B 및 C의 좌표축에 상응한 벡터로 나타나면, 2개의 교차지점은 다음 수학식17 내지 26의 방정식을 이용하여 산출하게 된다. The vector estimation method for z-axis correction is,

,

And

If is represented as a vector corresponding to the coordinate axes of A, B and C, respectively, the two intersection points are calculated using the equations of Equations 17 to 26.

,

중 실내 천장 의 기학적인 관계와 연관되는 하나를 선택하여 보정하게 된다.Vectors appear as two intersections as z-axis values

,

One of them is related to the geometrical relationship of the indoor ceiling.

The performance of the indoor position measuring method of the present invention was evaluated by simulating using a MATLAB.

As a result of evaluation by simulation using MATLAB, one important point of the structure of the indoor position measuring apparatus of the present invention is that the area of the position that can be measured is determined by the area of the light emitting diode illumination 10. If four light emitting diodes 11 can be seen in the dual image sensors 20 and 30, respectively, the coordinates (x, y, z) of the target position U can be estimated by the indoor position measuring apparatus of the present invention. . The position measuring area is reduced to a minimum when the dual image sensors 20 and 30 are parallel to the light emitting diode illumination 10.

3A and 3B show geometric dimensions for calculating a location measurement area, respectively, FIG. 3A is a side view of the LED lighting device 10, and FIG. 3B is a view of the LED lighting device 10 from above. It is a view. Assuming that the image sensors 20 and 30 are parallel to the light emitting diode illumination 10 as shown in FIGS. 3A and 3B, respectively, the position measuring area can be calculated by the equations of Equations 27 and 28.

Here, φ is half of the field of view (FOV) of the image sensor, q is the side length of the light emitting diode illumination 10, h is the light emitting diode illumination 10 and the dual image sensor (20,30) The vertical distance between and r is the length of the side of the location area.

In the MATLAB simulation model, assuming that the surface area of the light emitting diode illumination 10 is 1 × 1 m ² , the FOV of the dual image sensors 20, 30 is 45 °, and the light emitting diode illumination 10 and the dual The vertical distance between the image sensors 20 and 30 is called 3.5m. Therefore, the indoor position measuring apparatus of the present invention has an estimated position of 1.8x1.8 m ² when the light emitting diode illumination 10 has a 3.5m distance, and the parameters of the simulation of the matlab of the present invention. Is shown in FIG. 8.

Simulation of the MATLAB of the present invention assumes that the major axes of the dual image sensors 20 and 30 are parallel to the x axis of the position measurement area. The dual image sensors 20 and 30 apply an APS-C type 6 mega pixel image sensor used in Nikon cameras D40, D50, D70, D100, and Pantax K100D. And the simulation parameters are shown in detail in the table shown in FIG.

The pixels of the dual image sensors 20 and 30 are arranged to be arranged in two dimensions so that the image of the light emitting diode 11, that is, the optical signal image, is composed of a plurality of pixels. For this reason, it is necessary to determine the center of each light signal image before making other measurements.

If N pixels constitute an image of a specific light emitting diode 11, the center of the image is calculated using the following equation (29).

In Equation 29, j = 1, 2, 3... , N, (Nr, Nc) is the image center along the columns and rows of the image matrix, (Nrj, Ncj) is the column-row number of the pixel that matches the light emitting diode image, and j is the number of pixels.

 The MATLAB simulation results according to the least squares estimation method of the indoor measurement method of the present invention are as follows.

 Simulation of the least squares estimation method of the indoor measurement method of the present invention first evaluates the coordinates (x, y, z) of the fixed target position (U), and keeps the other elements constant, and the dual image sensor (20,30) The number of pixels per line is increased while increasing from 500 to 3008 in steps of 20 pixels.

The simulation results are shown in FIG. In FIG. 4, the horizontal axis represents pixels per line, and the vertical axis represents position errors in meters (m). The position error decreases as the number of pixels increases. An error represents a fluctuation state caused by quantum errors of pixels. The reason is that the image center is the center of the pixel obtained from the image center estimation using the above equation (29). However, the actual center of the image of the light emitting diode is not always the pixel center. As a result, a quantization error is obtained. The estimation errors from FIG. 4 are 0.156, 0.007 and 0.867 m along the x, y and z axes, respectively, when the pixel per line is 2948. FIG. In this case, the total error is 0.88m. The error along the x and y axes is much smaller than the error along the z axis.

In the least squares estimation method, as mentioned above, a small length was added to the z-axis of the 'D' reference light emitting diode 11 for calculation. As a result, the z-axis estimation error increased. In order to solve this problem, the unknown z-axis using the vector estimation method is estimated from the light emitting diodes 11 having three criteria, namely, position information A, B, and C, respectively.

The MATLAB simulation results according to the vector estimation method are as follows.

Three reference light emitting diodes 11 are required for the three-dimensional unknown position vector estimation method, and data corresponding to the reference light emitting diodes 11 is used. The pixel per line is increased from 500 to 3008 to understand the effect of pixel size on estimation error. All other variables remain unchanged as with the LSE described above. The results of the vector estimation method are as shown in Fig. 5, and the horizontal and vertical axes represent the number of pixels per line and the estimation error, respectively.

Estimation errors are 0.212, 0.078 and 0.013 m along the x, y and z axes, respectively, when the pixel per line is 2948. The total error is 0.226m. Also, as shown in Fig. 5, the vector estimation method gives a smaller error along the z-axis than the least square estimation method. In contrast, the errors along the x and y axes are larger than the least squares estimation method. Also, the error along the x-axis is larger than the error along the y-axis, since in the simulation, the major axes of the dual image sensors 20 and 30 are parallel to the x-axis, since the error along the x-axis is greater than the error along the y-axis. .

In summary, the least squares estimation is used for the x-axis and the y-axis, and the vector estimation for the z-axis in order to obtain a good estimate of the coordinates (x, y, z) of the target position U as a whole. Should be. Estimation errors and overall estimation errors from the combination of least squares estimation and vector estimation along different axes are shown in FIG. 6. The total estimation error according to the specific position is 0.156m when the number of pixels per line is 2948.

In the present invention, the relationship between the distance L and the position error of the optical lenses 21 and 31 is as follows.

In the present invention, in order to find the relationship between the distance (L) of the optical lens (21, 31) and the position error, the distance between the center of the lens from 4cm to 20cm in 2cm steps, the 32761 experiment using the following equation 30 Compute the root mean square (RMS) of the error location (Erms) of the location.

Where n is the number of positions to be estimated and Err _n is an estimation error of the nth position. The result is shown in Fig. 7A, and the RMS position error decreases in both the vector estimation method and the least-squares estimation method as the distance L between the two optical lenses 21 and 31 increases. Improvements in location performance are important up to 10 cm distance. At 10 cm, the vector and least squares estimation-vector estimation are 0.1239 and 0.09333, respectively. If the lens distance increases more than 7.2 cm, the RMS error of the least squares estimation-vector estimation becomes smaller than the error of the vector estimation. Since there is a trade-off between the location estimate area and the distance between the dual image sensors 20 and 30, it should be well defined while keeping the distance between the sensors 20 and 30 as small as possible. In order to establish the relationship between the RMS error and the distance of the optical lenses 21 and 31, the RMS error for the least squares estimation-vector estimation method was compared as a graph of the quadratic exponential function. This relationship is as shown in Equation 31 below.

Therefore, in the present invention, the indoor position measuring method using the light emitting diode illumination 10 and the dual image sensors 20 and 30 can minimize the position error within a range of several centimeters. Compared to the device, it is possible to perform the position measurement more precisely, there is an advantage that can be reduced to light and thin.

10: light emitting diode illumination 11: light emitting diode
20,30: Dual image sensor 21,31: Optical lens
22,23: image element 40: controller

Claims (14)

A light emitting diode illumination configured to receive a plurality of modulated light emitting diode position signals and convert the light emitting diode into an optical signal;
A dual image sensor installed to be spaced apart from the light emitting diode illumination to receive an optical signal and convert the light signal into an electrical signal;
And receiving and modulating the electrical signals output from the dual image sensors, thereby obtaining position information of a plurality of light emitting diodes, and calculating a coordinate of a target position using the obtained position information of the plurality of light emitting diodes. Indoor positioning device characterized in that. The indoor positioning device according to claim 1, wherein the light emitting diode illumination is provided with a plurality of light emitting diodes arranged in a horizontal direction and a vertical direction, respectively. The method of claim 1, wherein the light emitting diode illumination receives the modulated four light emitting diode position signals and converts each of them into an optical signal and irradiates the light emitting diode position signals. Indoor positioning device, characterized in that for indicating. The indoor positioning device of claim 1, wherein the dual image sensors are spaced apart from each other on the same plane. The optical image sensor of claim 4, wherein the dual image sensor comprises: an optical lens configured to transmit and receive an optical signal;
And an image element installed under the optical lens and configured to irradiate an optical signal transmitted through the optical lens and convert the optical signal into an electrical signal. The indoor positioning device according to claim 1, wherein the image device comprises an image pickup device or a plurality of photodiodes. The indoor position measuring apparatus according to claim 1, wherein the controller calculates an intermediate position of a straight line connecting the centers of the plurality of optical lenses as coordinates of a target position. Storing a distance between a focal length and an optical lens of the optical lens, each of which is provided in the dual image sensor;
Demodulating electrical signals according to the modulated plurality of light emitting diode position signals and storing position information of the plurality of light emitting diodes;
Calculating and storing distance information between a plurality of light emitting diodes and a target position using a distance between a focal length of the dual image sensor and an optical lens provided in each of the dual image sensors;
Calculating coordinates of a target location using location information of the plurality of light emitting diodes and distance information between the plurality of light emitting diodes and a target location;
And calculating the coordinate error of the calculated target position when the coordinates of the target position are calculated. The method of claim 8, wherein the calculating of the distance information between the plurality of light emitting diodes and the target position is repeated by calculating the following equation according to the number of the plurality of light emitting diodes.

here,

,

,

,

,

,

,

,
d _i is the distance between the light emitting diode and the coordinate of the target position, _i of i is 1 to 4, i ₁ and i ₂ are the distance from the center of the image sensor of the dual image sensor to the center of the optical signal image, respectively. , Pi ₁ and Pi ₂ are the distance the i ₁ and i ₂ is projected on the main axis of the image sensor, respectively, f is the focal length of the optical lens provided in the dual image sensor, respectively, L is provided in the dual image sensor The distance between the optical lenses is shown. The method of claim 8, wherein the calculating of the coordinates of the target position is calculated by the following quadratic equations.

,

,

,

Here, (x, y, z) is the coordinate of the target position, (x ₁ , y ₁ , z ₁ ), (x ₂ , y ₂ , z ₂ ), (x ₃ , y ₃ , z ₃ ) and ( x ₄ , y ₄ , z ₄ ) represent coordinates of the installation positions of the plurality of light emitting diodes, respectively, and d ₁ , d ₂ , d ₃ , and d ₄ each represent a distance between the coordinates of the target positions of the plurality of light emitting diodes. Indicates. The indoor position measuring method according to claim 8, wherein the coordinates of the target position in the step of calculating the coordinates of the target position are intermediate positions of a straight line connecting the centers of the plurality of optical lenses. The method of claim 8, wherein the correcting of the coordinate error of the target position comprises: correcting an error of the coordinate of the target position by a least squares estimation method when the coordinates of the target position are calculated;
Compensating for the z-axis error of the coordinates of the target position corrected by the least squares estimation method using a vector estimation method. 13. The method of claim 12, wherein the correcting by the least squares estimation method uses the following equation.

here,

,
And

Becomes The method of claim 12, wherein the vector estimation method uses the following equation.

,

here,

,

,

,

,

,

,

,

to be.

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