KR102271541B1 - Method for measuring device position using relative time difference between sound waves with reduced measurement error - Google Patents

Abstract

The present invention relates to a method for measuring a device position using a relative arrival time difference between two sound waves in which a measurement error is reduced through weighting for each section and frequency transformation of sound waves. According to the present invention, the distance or each coordinate between the vehicle and the device can be more precisely calculated using the arrival time and triangulation of the sound wave, and since the relative arrival time difference of the sound waves is used, the delay is not reflected in the distance calculation. The distance can be calculated independently, and the measurement error is minimized by preventing the occurrence of errors and imaginary roots, so that the accuracy of the device position measurement can be increased. In addition, since it is calculated using the time the sound waves output from a plurality of output devices reach the device, it is possible to determine which part of the car is closest to the user by securing the relative position coordinates of the device with respect to the car, and control Since the signal processing unit of the device functions the frequency of the sound wave and changes the phase, it is possible to minimize the measurement error by suppressing the reflected wave effect and improving the accuracy of the correlation.

Description

Method for measuring device position using relative time difference between sound waves with reduced measurement error

The present invention relates to a method for measuring the distance between a vehicle and a device. In more detail, it relates to a device position measurement method using the relative arrival time difference of two sound waves, in which a measurement error is reduced through weighting for each section and frequency transformation of sound waves.

In general, as a method of opening/closing a vehicle, a system for opening/closing a gate even at a predetermined distance within a predetermined area using a remote control key is actively used. In this regard, Prior Document 1 discloses an operating system for controlling the opening and closing of a vehicle using a smart key.

As such, the existing method using a smart terminal is vulnerable to radio wave hacking, so there is a security problem of the vehicle opening/closing control system. To solve this, various devices and methods for secure distance and location measurement are used.

As an example, Wonkey Co., Ltd., the applicant of the present invention, has developed a triangulation algorithm using the time difference of each sound wave in a vehicle opening/closing system using an encrypted sound wave and a smart terminal. This triangulation algorithm is a method designed to solve the instability of the delay that occurs during Bluetooth communication between the smart terminal and the MCU of the vehicle.

However, due to the large distance error compared to the time difference error due to the high speed of sound waves and the complicated calculation to obtain an analytic solution using approximation, a large error may occur even in a minute error or an imaginary root may occur due to the occurrence of negative numbers within the square root of the analytical solution. can

In order to prevent such errors and imaginary roots from occurring, the present invention proposes a position measurement technique that is robust to errors through the relative arrival time difference of two sound waves and weighting for each section, and describes a method for reducing measurement errors through frequency transformation of sound waves. do.

Republic of Korea Patent Registration 10-1316873 (Registered on Oct. 2, 2013)

The technical problem of the present invention is to propose a triangulation algorithm utilizing the time difference of sound waves.

Another technical problem of the present invention is to solve an error caused by a high speed of sound waves in a triangulation algorithm.

Another technical task of the present invention is to propose a position measurement technique robust to errors through the relative arrival time difference of two sound waves and weighting for each section in order to prevent errors, and to reduce the measurement error through frequency transformation of sound waves.

According to an aspect of the present invention, the control unit of the device calculates the position difference according to the relative arrival time difference of sound waves output from a plurality of output devices provided in the vehicle to calculate a plurality of straight line graphs that are a set of two-dimensional position coordinates of the device In order to prevent the occurrence of errors and imaginary roots, a position measurement technique robust to errors is used through the relative arrival time difference of two sound waves and weighting for each section, and the signal processing unit of the car transforms the frequency of the sound wave to measure the position of the device. Minimize possible errors.

According to the present invention, it is possible to more precisely calculate the distance or each coordinate between the vehicle and the device using the arrival time of the sound wave and triangulation.

According to the present invention, since the relative arrival time difference of sound waves is used, the delay is not reflected in the distance calculation, so that the distance can be calculated independently of the delay.

According to the present invention, since the measurement error is minimized by preventing the generation of errors and imaginary roots, it is possible to increase the accuracy of the position measurement of the device.

According to the present invention, since it is calculated using the time the sound waves output from the plurality of output devices reach the device, it is possible to determine which part of the car is closest to the user by securing the relative position coordinates of the device with respect to the car. can

According to the present invention, since the signal processing unit of the control device functions the frequency of the sound wave and changes the phase, it is possible to minimize the measurement error by suppressing the reflected wave effect and improving the accuracy of the correlation.

1 is a diagram showing the configuration of a position measuring system according to an embodiment of the present invention.
2 is a diagram schematically illustrating a sequence of a device position measurement method using a relative arrival time difference between sound waves according to an embodiment of the present invention.
3 is a view showing a plurality of output devices provided in a vehicle according to an embodiment of the present invention.
4 is a coordinate system illustrating positions of a first output device, a second output device, and a device provided in a vehicle according to an embodiment of the present invention.
5 is a coordinate system illustrating a first straight line graph according to an embodiment of the present invention.
6 is a view showing a plurality of linear graphs calculated by applying the device position measuring method according to an embodiment of the present invention to a plurality of output devices.
7 is a diagram illustrating an error generated by a reflected wave when a single frequency is used according to an embodiment of the present invention.
8 is a diagram illustrating a result of suppressing a reflected wave effect through a function of a frequency according to an embodiment of the present invention.

Hereinafter, 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 can easily implement them. However, the present invention may be implemented in several different forms and is not limited to the embodiments disclosed below. In addition, in order to clearly disclose the present invention in the drawings, parts irrelevant to the present invention are omitted, and the same or similar symbols in the drawings indicate the same or similar components.

Objects and effects of the present invention will become clearer through the following detailed description, but the objects and effects of the present invention are not limited only by the following description. In addition, in describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

Prior to the detailed description of the invention, in the case of the existing patent application 10-2020-0024888 (2020.02.28.) developed by Wonkey Co., Ltd., the applicant of the present invention, in general, a piezo speaker provided as a parking assistance system in a car is used. The invention will also be described on the premise of the use of the vehicle parking assistance system.

In addition, what will be described as sound waves below refers to radio waves of tens to hundreds of kilohertz (kHz) including sound waves or ultrasonic waves, and it is clear that only sound signals that can be actually heard by humans or animals are not referred to as sound waves.

1 is a diagram showing the configuration of a position measuring system according to an embodiment of the present invention. Referring to FIG. 1 , the position measuring system according to the present invention includes a vehicle 100 and a device 200 .

In detail, the vehicle 100 is configured to include a plurality of output devices 110 for outputting sound waves (H) and a control device 120 for transmitting an electrical output signal (V) to the plurality of output devices 110 , and , the device 200 is configured to include an input unit 210 for receiving the sound wave (H) output from the output device 110 of the vehicle 100 and a control unit 220 for processing data related to the location.

In more detail, the output device 110 of the vehicle 100 is provided in plurality inside or outside the vehicle 100, and generates sound waves (H) according to the electrical output signal (V) of the control device 120 to the device ( 200) is sent. The control device 120 that transmits the electrical output signal V to the output device 110 includes a signal processing unit 121 that generates and modulates the electrical output signal V and an electrical output generated by the signal processing unit 121 . It is provided to include an output circuit 122 that transmits the signal V to the plurality of output devices 110 .

The sound wave H transmitted from the output device 110 of the vehicle 100 may be a stereo signal (eg, 2.1 channel or 5.1 channel, etc.), and may be a signal having a frequency in the range of 2 to 24,000 Hz. More preferably, it may be a signal of a band of 19 to 21 kHz, and the sound wave of the corresponding frequency band is a sound wave of an inaudible band that people generally do not hear well.

Since the sound wave H transmitted from the channel Ch of each output device 110 provided in the vehicle 100 has different frequencies, the sound wave transmitted from any channel Ch at any time through correlation It can be distinguished whether (H) has reached the device 200 . It can also be calculated through triangulation using Heron's formula based on Time of Arrival (ToA) or Time Difference of Arrival (TDoA). Here, Heron's formula is the formula for finding the area through the lengths of the three sides of a triangle.

In a preferred embodiment, the signal processing unit 121 of the control device 120 functions by increasing or decreasing the magnitude of the generated electrical output signal V over time to function the frequency of the sound wave H output from the output device 110 . can do. A detailed description thereof will be described later with reference to FIGS. 7 and 8 .

2 is a diagram schematically illustrating a sequence of a method for measuring a position of a device 200 using a relative arrival time difference (dt) between sound waves (H) according to an embodiment of the present invention.

Referring to FIG. 2 , when the plurality of output devices 110 provided in the vehicle 100 outputs sound waves H, the input unit 210 of the device 200 transmits them. In detail, the first sound wave H1 and the second sound wave H2 output from the first output device 111 and the second output device 112, respectively, arrive at the input unit 210 of the device 200 . At this time, since the first output device 111 and the second output device 112 have a relative position difference n up to the device 200, the arrival time of the first sound wave H1 and the second sound wave ( A relative difference (dt) occurs in the arrival time of H2).

The control unit 220 of the device 200 measures the relative time difference dt at which the first sound wave H1 and the second sound wave H2 arrive at the input unit 210, and the first output device ( 111) and a position difference n from the second output device 112 to the device 200 is calculated.

Thereafter, the controller 220 of the device 200 uses a triangulation method based on the calculated plurality of position differences n, and a plurality of straight lines that are a set of two-dimensional position coordinates of the device 200 with respect to the ground. The distance between the vehicle 100 and the device 200 is calculated by calculating the graph L and measuring the position of the device 200 using a plurality of linear graphs L. Hereinafter, a calculation process and algorithm performed by the controller 220 of the device 200 will be described in more detail with reference to FIGS. 3 to 6 .

3 is a view showing a plurality of output devices 110 provided in the vehicle 100 according to an embodiment of the present invention.

As shown in FIG. 3 , when the channels Ch of the output device 110 provided in plurality are sequentially from the left as the first channels Ch1 to the fourth channels Ch4, the first channels Ch1 to the fourth channels It is assumed that all (Ch4) are located on the same y-coordinate in the two-dimensional coordinate system with respect to the ground, that is, on the same line. In the case of four channels (Ch), when four output devices 110 are paired two by two, a total of six pairs are obtained as follows.

[Ch1-Ch2 / Ch1-Ch3 / Ch1-Ch4 / Ch2-Ch3 / Ch2-Ch4 / Ch3-Ch4]

In each pair, the left output device 110 is called a first output device 111 , and the right output device 110 is called a second output device 112 , and the first output device 111 is referred to as a two-dimensional coordinate system based on the ground. ) is (0, 0), the x-coordinate difference between the first output device 111 and the second output device 112 is a, and the position of the device 200 is (x, y). This can be arranged as shown in FIG. 4 to be described later.

4 is a coordinate system illustrating positions of the first output device 111 , the second output device 112 , and the device 200 provided in a vehicle according to an embodiment of the present invention.

It is difficult to obtain the absolute length (m) between the device 200 and the first output device 1110 due to the instability of the delay generated during sound wave communication, but the sound waves (H) generated by each output device 110 Since the relative arrival time difference (dt) of dt can be measured, the position difference (n) of each output device 110 from the device 200 can be calculated. Here, the absolute length m is described as a variable m, and the position difference n of each output device 110 is described as a variable n. The position difference n of each output device 110 calculated by the above-mentioned bar is as the following Equation (1).

(v: 음파의 속도, dt: 두 음파의 도달 시간 차이)Equation (1):

(v: speed of sound wave, dt: difference in arrival time of two sound waves)

At this time, if the relationship between the variables of FIG. 3 is arranged, Equation (2) is obtained, and when Equation (2) is solved for y, it is expressed as Equation (3).

Equation (2):

Equation (3):

The control unit 220 of the device 200 calculates a plurality of straight line graphs L, which is a set of two-dimensional position coordinates of the device 200 with respect to the ground, through the above equations, and the calculated plurality of linear graphs L ) to calculate the distance between the vehicle 100 and the device 200 by measuring the position of the device 200 .

5 is a coordinate system illustrating a first straight line graph L1 according to an embodiment of the present invention. In the first line graph L1 , the variable n of the position difference n of each output device 110 is 0.3 among the plurality of line graphs L expressing the above-mentioned formula (3), and the first output device 111 ) and the x-coordinate difference variable a of the second output device 112 is a graph expressed on the basis of 0.5.

That is, when the relative position difference (n) of the first output device (H1) and the second output device (H2) is obtained using the relative arrival time difference (dt) of the first sound wave (H1) and the second sound wave (H2), it is Although it cannot be specified as a single point, it can be expressed as a straight line graph L, which is a set of two-dimensional position coordinates in which the device 200 can exist. If this is expressed as an algorithm, the sequence is as follows.

(1) The first output device 111 and the second output device 112 are relative to each other based on the relative time difference dt at which the first sound wave H1 and the second sound wave H2 arrive at the device 200 Calculation of position difference (n)

일 때, i 간격(ex. 0.01m)으로 k+1개의 값을 가지는 x좌표 배열을 생성하며 아래와 같은 기준을 따름(2)

When , an x-coordinate array with k+1 values is created with an i interval (ex. 0.01m), and the following criteria are followed.

[for j=0:k]

x(j)=(a+n)/2 - i*j*n/abs(n)

[end]

(3) Substitute the x-coordinate array into Equation (3) to calculate the y-coordinate array

(4) When n=0, it is expressed as x=(a+n)/2 (a straight line parallel to the y-axis)

(5) Convert to the absolute coordinate system by adding the coordinates of the first output device 111 to the obtained (x, y) coordinates

6 is a diagram illustrating a plurality of linear graphs L calculated by applying the device 200 position measuring method according to an embodiment of the present invention to a plurality of output devices 110 .

Referring to FIG. 6 , if the process of (1) to (4) according to the above algorithm is performed for the six pairs described above, six straight line graphs (L) can be expressed on two-dimensional coordinates based on the ground. have. In an ideal case, six straight line graphs (L) are gathered at one point of intersection (P). At this time, if the above process is performed through the experimental data with errors, a plurality of intersections (P) are generated differently from the ideal case, and when there is no intersection (P), that is, there may be a case where an imaginary root occurs in triangulation. can

As a preferred embodiment for this, a weight (W) that can be used in a non-ideal case will be described. According to the above-described exemplary embodiment, in an ideal case, six linear graphs L may be gathered at one intersection P, but if not ideal, there is a problem that an imaginary root may be generated. Therefore, in this case, in order to track the location of the device 200, a sector scoring method that provides a score through a weight W is proposed.

The sector-by-sector scoring method refers to a method in which a space is divided into sectors and then a section through which the straight line graph L passes the most is determined as a location in which the device 200 exists. At this time, since there may be a section through which all the straight line graphs (G) pass, a weight (W) is given to give a score for each section. In the case of FIG. 6, a total of 84 sectors were divided into 6 horizontally and 14 vertically.

There are various cases of the weight W, but in the present invention, the length within the section of the straight line graph L passing through one section is used as a basis. In a more preferred embodiment, in addition to the length of the straight line graph (L) within the section, the size of the sound wave (H) received by the input unit 210 of the device 200 may also be a factor of the weight (W), In this case, the following method is used in which the weight W is proportional to the length and size of the sound wave H.

[Weight (W) = length of nth line graph (L) passing through the section * sum of sound wave (H) pairs of nth line graph (L) / sound wave (H) size of all channels (Ch) sum of]

Finally, through the above process, the controller 220 of the device 200 adds all the n weights W as above in each section to compare the sizes for each section, and selects the largest weight W among them. A section having the device 200 is specified as a section in which the device 200 exists.

7 is a diagram illustrating an error generated by a reflected wave when a single frequency is used according to an embodiment of the present invention.

In the device 200 position measuring system according to the present invention, a specific frequency in a plurality of sound waves (H) transmitted from a plurality of output devices 110 provided in the vehicle 100 and reaching the input unit 210 of the device 200 In order to extract the arrival time of the sound wave H, a general frequency analysis method such as filtering and correlation is used.

Referring to FIG. 7 , it can be confirmed that an error caused by a reflected wave occurred about 0.82494m in a measurement experiment using a single frequency. As such, in the case of the present invention, since an error of 'ms' unit of arrival time may generate an error of several 'm' units, higher precision is required in the frequency extraction technique.

As a preferred embodiment, a method for further improving the accuracy of position measurement by changing the frequency will be described later with reference to FIG. 8 .

8 is a diagram illustrating a result of suppressing a reflected wave effect through a function of a frequency according to an embodiment of the present invention.

Referring to FIG. 8 , it can be confirmed that the position measurement method according to the present invention minimizes the measurement error by suppressing reflection and effect through a method of functionalizing the frequency of the sound wave (H) and a method of changing the phase of the frequency.

As a preferred embodiment for minimizing the measurement error, a method of functionalizing the frequency by changing the frequency according to time instead of a generally used single frequency may be used. As described above in FIG. 7 , when a typical single frequency is used, an error due to a reflected wave occurs, but when the frequency is functionalized, the effect on constructive and destructive interference due to the reflected wave can be reduced. The position measuring system according to the present invention functions (increasing 4000 Hz linearly for 8 ms) the frequency of the sound wave (H) through the signal processing unit 121 of the control device 120 provided in the vehicle 100, thereby reducing the reflected wave effect. It is possible to minimize the measurement error by suppressing it.

As another embodiment for minimizing the measurement error, a method of changing the phase of the frequency may be used. In detail, a phase of a general sine wave is defined as 1, and the phase of this waveform is vertically inverted, that is, a phase obtained by multiplying all values by -1 is defined as 0. After that, when a new waveform is configured by a combination of 0 and 1 of the phase, it is possible to not only improve the accuracy of correlation and reduce the effect of the reflected wave, but also encode the sound wave (H) and transmit information. By changing the phase of the frequency through the signal processing unit 121 of the control device 120 provided in the vehicle 100, the position measurement system according to the present invention improves the accuracy of the correlation and reduces the reflected wave effect. Measurement error can be minimized.

The above-described preferred embodiments of the present invention have been disclosed for the purpose of illustration, and those skilled in the art with common knowledge about the present invention will be able to make various modifications, changes and additions within the spirit and scope of the present invention. It should be regarded as belonging to the scope of the above claims. In addition, a person of ordinary skill in the art to which the present invention pertains, various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the present invention. It is not limited.

In the exemplary system described above, the methods are described on the basis of a flowchart as a series of steps or blocks, however, the present invention is not limited to the order of steps, and some steps may occur in a different order or concurrent with other steps as described above. can In addition, those skilled in the art will understand that the steps shown in the flowchart are not exhaustive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention.

100: car 110: output device
111: first output device 112: second output device
120: control device 121: signal processing unit
122: output circuit 200: device
210: input unit 220: control unit
V : Electrical output signal H : Sound wave
Ch: channel
m: absolute length n: relative position difference
dt : difference in arrival time between two sound waves L : straight line graph
P : intersection W : weight

Claims (5)

A vehicle 100 provided with a plurality of output devices 110 for outputting sound waves (H) and a control device 120 for transmitting an electrical output signal (V) to the plurality of output devices 110 ; and
A position measurement system comprising a device 200 including an input unit 210 for receiving a sound wave (H) output from the output device 110 of the vehicle 100 and a control unit 220 for processing position-related data In
The control unit 220 of the device 200,
By measuring the relative time difference dt at which a plurality of sound waves H generated from a plurality of output devices 110 provided in the vehicle 100 arrives at the input unit 210 of the device 200, the vehicle 100 ) calculates a position difference (n) from each of the plurality of output devices 110 to the device 200;
Calculate a plurality of straight line graphs (L), which is a set of two-dimensional position coordinates of the device 200 with respect to the ground, using triangulation based on the calculated plurality of position differences (n);
It is characterized in that the distance between the vehicle 100 and the device 200 is calculated by measuring the position of the device 200 using a plurality of straight line graphs L that are a set of two-dimensional position coordinates of the device 200 . A device position measurement method using the relative arrival time difference between sound waves with reduced measurement error.
According to claim 1, wherein the control unit 220 of the device 200,
When the intersection (P) of the plurality of straight line graphs (L) is one, one intersection (P) is specified as the position of the device (200);
When there are a plurality of intersection points (P) of the plurality of straight line graphs (L),
The location of the device 200 exists in a section through which the most number of straight line graphs L among the plurality of straight line graphs L passes by dividing the coordinate system of the plurality of line graphs L according to a preset criterion. A device position measurement method using the relative arrival time difference between sound waves with reduced measurement error, characterized in that it is specified as a section.
According to claim 1, wherein the control unit 220 of the device 200,
When there are a plurality of intersection points (P) of the plurality of straight line graphs (L),
At least one preset weight (W) is given to each section of the coordinate system of the plurality of straight line graphs (L) divided according to a preset criterion,
Measurement error, characterized in that the section in which the sum of the one or more weights W is the largest among sections of the coordinate system of the plurality of straight line graphs (L) as the section in which the location of the device 200 exists A device position measurement method using the relative arrival time difference between sound waves with reduced .
According to claim 1, The control device 120 of the vehicle 100,
a signal processing unit 121 for generating and modulating an electrical output signal (V); and
Relative between sound waves with reduced measurement error, characterized in that it includes an output circuit 122 for transmitting the electrical output signal V generated by the signal processing unit 121 to the plurality of output devices 110 . Device position measurement method using arrival time difference.
According to claim 4, The signal processing unit 121 of the control device 120,
Using the relative arrival time difference between sound waves with reduced measurement error, characterized in that the frequency of the sound wave (H) output from the output device 110 is functionalized by increasing or decreasing the magnitude of the generated electrical output signal (V) with time How to measure device position.

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