KR102640920B1 - Apparatus and method for mesuring position of multiple target, computer-readable storage medium and computer program - Google Patents

Abstract

The multi-target position measuring device of the embodiment includes a plurality of optical transmitters that transmit optical signals, an optical signal generator that modulates optical signals generated from the plurality of optical transmitters according to pattern information, and light transmitted from the optical transmitters. A plurality of targets that reflect signals, a plurality of light receivers that receive a plurality of optical signals reflected from the plurality of targets and measure each light intensity, and pattern information of the plurality of light intensities and the optical signal Based on this, it may include a position measuring unit that measures each position of the plurality of targets.
The embodiment has the effect of preventing an increase in equipment cost and design complexity by developing an algorithm for measuring the position of multiple targets.

Description

Device and method for measuring position of multiple targets, computer-readable recording medium, and computer program {APPARATUS AND METHOD FOR MESURING POSITION OF MULTIPLE TARGET, COMPUTER-READABLE STORAGE MEDIUM AND COMPUTER PROGRAM}

The embodiment relates to a multi-target position measuring device, and more specifically, to a multi-target position measuring device and method for recognizing the positions of multiple targets indoors based on visible light.

Recently, as daily life indoors has increased, location recognition services, which were mainly provided for outdoor spaces, are expanding their scope to include indoor location recognition services. However, indoor location recognition services have several limitations compared to outdoor location recognition systems due to the fact that they are applied in indoor spaces.

The most common limitation is that satellite signals cannot pass through indoor spaces. Accordingly, existing indoor location recognition methods used various types of signals such as infrared, ultrasonic, Bluetooth, RFID (Radio Frequency IDentification), UWB (Ultra-Wide Band), and WLAN (Wireless Local Area Network). It has problems such as short transmission distance, multipath effect, low accuracy, signal interference, and high cost for system construction.

Visible light has excellent security and non-interference due to the straight path of light, and because the usable frequency band is wide and high bandwidth can be used, it is easy to divide between signals. In addition, by using low-power LED lighting, energy efficiency is high and there is no RF interference, so it is suitable for use in places such as hospitals and airplanes.

Existing visible light-based indoor positioning technology has the burden of implementing location recognition algorithms in individual terminals themselves, and through two-way communication, terminal users can monitor physical environmental variables (LED location, modulation method of frequency/code, etc.) within the space. There are drawbacks that you should be aware of. In addition, there are limits to industrial application due to the methodological limitations of the system, such as increased equipment costs and design complexity for detecting multiple targets simultaneously.

Recently, various passive optical positioning methods have been researched, but due to structural limitations, only the approximate shadow shape of an object can be recognized using multiple high-precision sensors, or high-precision localization through reflection has been implemented, but only a single signal is possible in a narrow range. There is a problem of only recognizing targets, and methods for simultaneously locating multiple targets in a wide space have not been studied.

Korean Patent No. 10-2204191 (registered on January 12, 2021)

In order to solve the above-mentioned problems, the purpose of the embodiment is to provide a device and method for measuring the positions of multiple targets in a large space.

The multi-target position measuring device of the embodiment includes a plurality of optical transmitters that transmit optical signals, an optical signal generator that modulates optical signals generated from the plurality of optical transmitters according to pattern information, and light transmitted from the optical transmitters. A plurality of targets that reflect signals, a plurality of light receivers that receive a plurality of optical signals reflected from the plurality of targets and measure each light intensity, and pattern information of the plurality of light intensities and the optical signal Based on this, it may include a position measuring unit that measures each position of the plurality of targets.

The position measuring unit may measure the position of the target by comparing the plurality of light intensities with the pattern information.

The light intensities received from the plurality of light receivers can be calculated by Equation 1.

[Equation 1]

The H _LiTjPk can be calculated by Equation 2.

[Equation 2]

The target may include a hemispherical regular reflector or a planar diffuse reflector.

In addition, the embodiment relates to a method for measuring the position of multiple targets performed in a position measuring unit of a position measuring device for multiple targets, by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets to provide light. It may include measuring the intensity and measuring each position of the plurality of targets based on the received light intensity and pattern information of the plurality of light transmitters.

In addition, the embodiment is a computer-readable recording medium storing a computer program, wherein the computer program, when executed by a processor, receives optical signals received from a plurality of optical receivers through a plurality of optical transmitters and a plurality of targets. The processor performs an operation including measuring the light intensity and measuring each position of the plurality of targets based on the received plurality of light intensities and pattern information of the plurality of light transmitters. It may contain commands to do so.

In addition, the embodiment is a computer program stored in a computer-readable recording medium, where, when executed by a processor, the computer program receives optical signals received from a plurality of optical receivers through a plurality of optical transmitters and a plurality of targets. The processor performs an operation including measuring the light intensity and measuring each position of the plurality of targets based on the received plurality of light intensities and pattern information of the plurality of light transmitters. It may contain commands to do so.

The embodiment has the effect of preventing an increase in equipment cost and design complexity by developing an algorithm for measuring the position of multiple targets.

In addition, the large-scale analysis system and ultra-low power of the embodiment can effectively measure the location of the target.

1 is a block diagram showing a device for measuring the position of multiple targets according to an embodiment.
Figure 2 is a diagram showing the main variables of the Lambertian radiation system.
FIG. 3 is a diagram illustrating an optical signal flowchart of a multi-target position measurement device according to an embodiment.
4 to 6 are diagrams illustrating an example of recognizing the positions of multiple targets according to an embodiment.
Figure 7 is a block diagram showing a method for measuring the position of multiple targets according to an embodiment.

Hereinafter, the embodiment will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a multi-target position measuring device according to an embodiment, FIG. 2 is a diagram showing main variables of a Lambertian radiation system, and FIG. 3 is an optical signal of a multiple target position measuring device according to an embodiment. This is a flowchart, and FIGS. 4 to 6 are diagrams showing an example of recognizing the positions of multiple targets according to an embodiment.

Referring to FIG. 1, the multi-target position measurement device 1000 according to an embodiment includes a plurality of optical transmitters 100 that transmit optical signals, a signal generator 200 that modulates the optical signals according to pattern information, and , a plurality of targets 300 that reflect the optical signals transmitted from the optical transmitter 100, and a plurality of optical signals that receive the plurality of optical signals reflected from the plurality of targets 300 and measure the intensity of each light. It may include a receiving unit 400 and a position measuring unit 500 that measures each position of the plurality of targets based on the plurality of light intensities and pattern information of the optical signal.

The light transmitting unit 100 may generate visible light. The light transmitting unit 100 may emit visible light. Visible light may be an electromagnetic wave with a wavelength of 380 nm to 780 nm. The light transmitting unit 100 may include a light emitting diode (LED) 110. A plurality of LEDs 110 may be provided.

The signal generator 200 may modulate an optical signal to generate light according to pattern information. For example, the pattern information may include signal pattern information that generates light at regular time intervals. Alternatively, the pattern information may include signal pattern information that generates light so that the wavelength of visible light has a different frequency. Accordingly, the plurality of light transmitting units 100 may transmit light using different pattern information.

Target 300 may include a reflective object. The target 300 may reflect light transmitted from the light transmitter 100. A plurality of targets 300 may be provided. The target 300 may be mounted on a person or object whose location needs to be measured. The target 300 may include, but is not limited to, a hemispherical regular reflector or a planar diffuse reflector.

The optical receiver 400 may detect the optical signal reflected from the target 300 and measure the signal strength. The light receiver 400 may include a plurality of light sensors 410. The optical receiver may include a photo diode.

The position measuring unit 500 may measure each position of the plurality of targets 300 based on a plurality of light intensities and pattern information of the optical signal. The method for measuring the position will be described with reference to FIGS. 2 to 6.

First, with reference to FIGS. 2 and 3 , necessary variables for explaining the position measurement method according to the embodiment will be described.

In indoor location recognition systems based on visible light communication, the Received Signal Strength (RSS) method is generally used by setting the LED 110 as a reference point and measuring the DC gain of the optical signal measured by the optical sensor 410. Mainly used. The optical signal by LED 110 can be treated as a Lambertian source when emitted in an indoor environment. Therefore, in a LOS (Line-Of-Sight) environment, the direct current gain (H) of the wireless channel may follow the Lambertian radiation pattern as shown in Equation 1.

[Equation 1]

Here, A is the detection area of the receiver (light sensor), d is the distance between the transmitter (LED) and the receiver, and ψ mean the radiation angle and incident angle, respectively. m and n are each , It is expressed as _1/2 and ψ _1/2 represent the half angle of the LED and the half angle of the receiver. In Figure 2, the main system parameters of Lambertian radiation are shown. Ts(ψ) is the optical gain of the filter and g(ψ) is the gain of the receiver's conscript lens. Finally, rect(x) is a spherical function, |x| When ≤ 1, rect(x) = 1, otherwise, rect(x) = 0. FOV (Field of View) is the observation field of view of the LED. In general, the radiation angle is If is always smaller than FOV, then The value of is always 1.

In an embodiment, the wireless channel gain (H) formula summarized above can be simplified and expressed as Equation 2.

[Equation 2]

Here, H(0) is DC gain, so if the output power of the LED is P _T and the power received from the receiver is P _R , satisfies the consciousness. In the present invention, it is assumed that the power of all receivers is the same, and the intensity of light can be explained based on the direct current channel gain.

When the target 300 is a hemispherical regular reflector, the signal intensity of the reflected light reflected from the target 300 is expressed as Equation 3. Equation 3 can be expressed using Equation 2, which is a Lambertian radiation pattern equation.

[Equation 3]

Here, R is a constant including the reflectance of the reflector and the effect of light spreading caused by the curved surface of the hemispherical reflector, The radiation angle from the LED to the target is is the angle of incidence at which the light reflected from the target is directed to the receiver, class represents the distance between the LED and the target and the target and the PD, respectively.

In Equation 3, all variables are the coordinates of the target 300 by the equation below ( ) and location information of LED and PD ( ) can be replaced with. In other words, Equation 3 is like Equation 4 and Equation 5, It can be expressed as a function of .

[Equation 4]

[Equation 5]

When the target 300 is a flat diffuse reflector, the signal strength of the reflected light reflected from the target is expressed as Equation 6. Equation 6 can be expressed using Equation 2, which is a Lambertian radiation pattern equation.

[Equation 6]

here, is the signal intensity of the LED signal incident on the target (reflector), is the signal strength of the reflected light received from the PD, class represents the radiation constant between LED and target and between target and PD, respectively.

Assuming that the position of the LED 110 is (0,0,0) (actual coordinates = coordinates on the drawing - LED coordinates), A and B can be expressed as follows.

[Equation 7]

[Equation 8]

here, can be expressed as Equation 9 using the inner product formula of the vector.

[Equation 9]

In Equation 9, the horizontal angle in the spherical coordinate system is Since can be expressed using x, y, z as follows, this value is It can be replaced with .

In the case of applying LED as PD, it is the same as above. It can be replaced with .

In summary, Equation 6 is It can be expressed as Equation 10, which is a function of .

[Equation 10]

On the other hand, in the case of multiple targets 300, the same code is applied to the reflected signals of the multiple targets 300 and are recognized as a simple sum, so direct location recognition through the signal strength of the single target 300 is not possible, and each An algorithm is needed to simultaneously estimate the coordinates of all targets through a simultaneous equation derived from the combination of transmitter and receiver.

Location information of the target 300 to be estimated ( ) is specified as an unknown number to express the signal strength (Equations 5 and 10) for a pair of LED-target-PD, and the equation for the actually received LED-PD pair can be expressed in Equation 11. Ultimately, there are 3N unknowns ( ) can be defined as a problem of calculating through M × K equations 12 derived for every LED-PD pair. (N: Number of targets, M: Number of LEDs, K: Number of PDs)

[Equation 11]

[Equation 12]

Here, since the signal strength of diffuse reflection varies depending on the angle at which light is incident and radiated to the reflector, additional processes such as additional measurement of the tilt of the reflector or calculation by assuming it as an unknown number may be required. When applied in an environment where there is no tilt of the target (reflector), this process is excluded.

As shown in FIG. 3, when the multi-target position measuring device according to the embodiment is composed of a plurality of LEDs 110, a plurality of targets 300, and a plurality of optical sensors 410, the light intensity is expressed by the equation 3, can be measured by Equation 11 and Equation 12.

With reference to FIGS. 4 to 6 , multi-target location recognition according to an embodiment is described as follows.

As shown in FIG. 4, there are four LEDs 110, and the positions of the plurality of LEDs 110 are (-2, -2, 0), (-2, 2, 0), (2, -2), respectively. , 0), (2, 2, 0). It can be assumed that there are two optical sensors 410 (PD) and the position of the optical sensors 410 is (-2, 0, 0) (2, 0, 0). There are two targets 300, the targets 300 are hemispherical regular reflectors, and the positions of the targets 300 can be assumed to be (-1, -1, 1.2), (0.5, 1, 1).

As shown in FIG. 5, the values of (a) and (b) may represent the intensity of reflected light moving through the path of LED -> target (reflector) -> optical sensor. The intensity of reflected light can be calculated by Equation 3. For example, the value of H _L1T1P1 may be 188.08, and the value of H _L3T2P2 may be 48.14. The value in (c) represents the intensity of the reflected light traveling through the path of the LED -> (all targets ->) optical sensor, which is the sum of the values in (a) and (b). It can be expressed as Equation 11.

The values shown in FIG. 5 are a breakdown of the theoretically calculated intensity of reflected light along each path, and the final light intensity actually received from the optical sensor is the values in FIG. 5c, which are applied to different patterns of LED signals. It can be received in a combined form.

The position measuring unit 500 can measure the position of the target through pattern information of the LED signal. For this purpose, the position measuring unit 500 may receive pattern information from the signal generating unit 200. As shown in FIG. 1, the position measurement unit 500 may be divided into a signal identification unit 510 and a calculation unit 530, but is not limited thereto. The signal identification unit 510 performs decoding, and the calculation unit 530 may perform a function of identifying the location.

As shown in FIG. 6, the LED may have the following pattern information depending on time. Pattern information can be collected from the signal generator.

Since the position measuring unit 500 knows the pattern of the LED, it can distinguish the signal of the LED and measure the position information of the target.

On the other hand, when the pattern information is frequency, the position measuring unit 500 knows the pattern information of the LED, so it can distinguish the signal of the LED and measure the position information of the target. Pattern information is not limited to this.

The calculation unit 530 of the position measurement unit 500 can measure multiple targets 300 under the assumption that the number of targets is known.

For example, the coordinates of multiple targets can be calculated by changing the x, y, and z values of each target and searching for the point where the value of the cost function is minimum through gradient descent. The positioning algorithm uses random starting location information selected through the above process when the system is first started, but during system operation, it can efficiently reduce calculation time by using the already known multi-target location information from the previous time.

As another example, the number of targets is increased, optimal multi-target positioning is performed according to the number of targets, and the number of targets is recognized by selecting the case where the cost function value for the positioning result is minimum. The target number recognition algorithm is applied when the system first starts, and can be applied intermittently when necessary as the system operates.

Here, the cost function is as shown in Equation 13.

[Equation 13]

Here, H _LjPk is the LED-PD signal measured through the signal identification unit as in [Table 1](c), and H _LjTiPk ' is calculated inversely through the target position as in [Table 1](a)(b). It may be an LED-target-PD signal.

Figure 7 is a block diagram showing a method for measuring the position of multiple targets according to an embodiment.

As shown in FIG. 7, the method for measuring the position of multiple targets according to the embodiment may be performed in the position measuring unit of the device for measuring the position of the multiple targets.

The method for measuring the position of multiple targets includes the steps of measuring light intensity by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets (S100), and measuring the light intensity of the plurality of received lights and the plurality of light intensity. It may include measuring the positions of each of the plurality of targets based on the pattern information of the optical transmitter (S200).

In the step of measuring the light intensity (S100), the light intensity may be measured using an optical signal received from the optical transmitter-target-light receiver. Here, the light intensity can be measured by Equations 3, 11, and 12.

In the position measuring step (S200), each position of the target can be measured by comparing light intensities and pattern information.

Various embodiments of the present document are software (e.g., instructions stored in a machine-readable storage media (e.g., memory (built-in memory or external memory)) that can be read by a machine (e.g., a computer). : program). The device is a device capable of calling instructions stored from a storage medium and operating according to the called instructions, and may include an electronic device according to the disclosed embodiments. When the command is executed by the control unit, the control unit can perform the function corresponding to the command directly or by using other components under the control of the control unit. Instructions may contain code generated or executed by a compiler or interpreter. A storage medium that can be read by a device may be provided in the form of a non-transitory storage medium. Here, non-transitory only means that the storage medium does not contain signals and is tangible, and does not distinguish whether the data is stored semi-permanently or temporarily in the storage medium.

According to embodiments, methods according to various embodiments disclosed in this document may be provided and included in a computer program product.

According to one embodiment, a computer-readable recording medium storing a computer program, comprising: measuring light intensity by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets, Includes instructions for causing a processor to perform a method including an operation for measuring each position of the plurality of targets based on the received light intensity and pattern information of the plurality of light transmitters. can do.

According to one embodiment, there is a computer program stored in a computer-readable recording medium, comprising: receiving optical signals received from a plurality of optical receivers through a plurality of optical transmitters and a plurality of targets to measure the light intensity; Includes instructions for causing a processor to perform a method including an operation for measuring each position of the plurality of targets based on the received light intensity and pattern information of the plurality of light transmitters. can do.

Although the above has been described with reference to the drawings and examples, those skilled in the art will understand that various modifications and changes can be made to the examples without departing from the technical spirit of the examples described in the claims below. You will be able to.

100: Optical transmitter
200: signal generator
300: Target
400: Optical receiver
500: Position measuring unit

Claims (12)

a plurality of optical transmitting units that transmit optical signals;
an optical signal generator that modulates optical signals generated from the plurality of optical transmitters according to pattern information;
a plurality of targets that reflect optical signals transmitted from the optical transmitter;
a plurality of light receivers configured to receive a plurality of optical signals reflected from the plurality of targets and measure respective light intensities; and
a position measuring unit that measures each position of the plurality of targets based on the plurality of light intensities and pattern information of the optical signal;
Including,
A multi-target position measurement device in which the light intensities received from the plurality of light receivers are calculated by Equation 1.
[Equation 1]

(Here, N refers to the number of targets, M refers to the number of optical transmitters, K refers to the number of optical receivers, and H _L1P1 refers to the light intensity received from the first optical transmitter to the first optical receiver through a plurality of targets. And H _L1T1P1 refers to the intensity of the optical signal received through the first optical transmitter, first target, and first optical receiver.) According to paragraph 1,
The position measuring unit,
A multi-target position measuring device that measures the position of the target by comparing the plurality of light intensities with the pattern information. delete According to paragraph 1,
The H _LiTjPk is a multi-target position measurement device calculated by Equation 2.
[Equation 2]

(Here, L _I is the ith light transmitter, T _j is the jth target, P _k is the kth light receiver, R is a constant including the reflectance of the target and the effect of light spread caused by the curved surface of the target, is the radiation angle from the optical transmitter toward the target, is the angle of incidence at which the light reflected from the target is directed to the light receiver, class represents the distance between the optical transmitter and the target, and the target and the optical receiver, respectively) According to paragraph 1,
The target is a multi-target position measurement device including a hemispherical regular reflector or a planar diffuse reflector. In the method of measuring the position of multiple targets performed in the position measurement unit of the multi-target position measuring device,
Measuring light intensity by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets; and
Measuring each position of the plurality of targets based on the received light intensity and pattern information of the plurality of light transmitters;
Including,
A method of measuring the position of a multiple target in which the light intensities received from the plurality of light receivers are calculated by Equation 1.
[Equation 1]

(Here, N refers to the number of targets, M refers to the number of optical transmitters, K refers to the number of optical receivers, and H _L1P1 refers to the light intensity received from the first optical transmitter to the first optical receiver through a plurality of targets. And H _L1T1P1 refers to the intensity of the optical signal received through the first optical transmitter, first target, and first optical receiver.) According to clause 6,
The step of measuring each position of the plurality of targets,
A method for measuring the position of multiple targets by comparing the light intensity with pattern information of the optical signal to measure each position of the plurality of targets. delete According to clause 6,
The H _LiTjPk is a method of measuring the position of multiple targets calculated by Equation 2.
[Equation 2]

(Here, L _I is the ith light transmitter, T _j is the jth target, P _k is the kth light receiver, R is a constant including the reflectance of the target and the effect of light spread caused by the curved surface of the target, is the radiation angle from the optical transmitter toward the target, is the angle of incidence at which the light reflected from the target is directed to the light receiver, class represents the distance between the optical transmitter and the target, and the target and the optical receiver, respectively) According to clause 6,
The target is a method of measuring the position of multiple targets including a hemispherical regular reflector or a planar diffuse reflector. A computer-readable recording medium storing a computer program,
When the computer program is executed by a processor,
Measuring light intensity by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets; and
Measuring each position of the plurality of targets based on the received light intensity and pattern information of the plurality of light transmitters,
A computer-readable recording medium including instructions for causing the processor to perform an operation where the light intensities received from the plurality of light receivers are calculated by Equation 1.
[Equation 1]

(Here, N refers to the number of targets, M refers to the number of optical transmitters, K refers to the number of optical receivers, and H _L1P1 refers to the light intensity received from the first optical transmitter to the first optical receiver through a plurality of targets. And H _L1T1P1 refers to the intensity of the optical signal received through the first optical transmitter, first target, and first optical receiver.) A computer program stored on a computer-readable recording medium,
When the computer program is executed by a processor,
Measuring light intensity by receiving optical signals received from a plurality of light receivers through a plurality of light transmitters and a plurality of targets; and
A step of measuring each position of the plurality of targets based on the plurality of received light intensities and pattern information of the plurality of light transmitters, wherein the light intensities received from the plurality of light receivers are expressed in Equation 1 A computer program including instructions for causing the processor to perform an operation calculated by .
[Equation 1]

(Here, N refers to the number of targets, M refers to the number of optical transmitters, K refers to the number of optical receivers, and H _L1P1 refers to the light intensity received from the first optical transmitter to the first optical receiver through a plurality of targets. And H _L1T1P1 refers to the intensity of the optical signal received through the first optical transmitter, first target, and first optical receiver.)

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