KR20210072678A - Method and apparatus for calculating the distance or angular coordinates between a vehicle and a smartphone using the arrival time of sound waves and triangulation - Google Patents

Abstract

The present invention relates to a method of precisely calculating a distance between a vehicle and a smartphone or coordinates of a vehicle and a smartphone using the arrival time of sound waves and triangulation. The method comprises the steps of: executing a smart key application; transmitting the Bluetooth connection request to the vehicle; transmitting a response to the Bluetooth connection request to the driver's mobile device; performing an operation of turning on the speaker; transmitting sound wave signals of different frequencies through the plurality of speaker channels; calculating a distance between the driver's mobile device and the vehicle based on the received sound wave signal; transmitting a control permission signal from the driver's mobile device to the vehicle; and preparing a door or a trunk to be unlocked or started when the vehicle receives the control permission signal.

Description

Method and apparatus for calculating the distance or angular coordinates between a vehicle and a smartphone using the arrival time and triangulation of sound waves{omitted}

The present invention relates to a smart key system for a vehicle. In more detail, it relates to a method and system for measuring the distance between a smart phone and a car operating as a smart key of the car or calculating the coordinates of the smart phone.

A car door or trunk opening/closing system using radio wave communication, which is currently generally applied, is vulnerable to radio wave hacking such as a relay station attack (hereinafter referred to as RSA). In addition, there is the inconvenience of having to separately carry a car key, that is, a key fob.

In order to overcome the limitations of this radio communication system, a method using encrypted sound waves and a smartphone is being developed. As an algorithm used at this time, the present invention proposes a method of measuring the distance between a vehicle and a smart phone through a time difference of sound wave communication, and transmitting a command through Bluetooth communication based on this. Here, in case the time synchronization between the smart phone and the vehicle ECU (Electronic Controller Unit) is unstable, more precise distance positioning calculation is required through triangulation using the time difference of each sound wave.

Korean Patent Publication No. 10-2018-0115783 (published on October 23, 2018)

It is an object of the present invention to provide a method and system for calculating a distance or each coordinate between a vehicle and a smart phone using the arrival time of sound waves and triangulation.

According to an aspect of the present invention, the method of determining the distance or angular coordinates between the vehicle and the smartphone using the arrival time of the sound wave and triangulation is the vehicle 250 and the vehicle 250 using the arrival time of the sound wave transmitted from a plurality of speaker channels. Calculate the distance or angular coordinates between the driver's mobile devices 200 . The method includes executing a smart key application on the driver's mobile device; transmitting a Bluetooth connection request transmitted from the driver's mobile device to the vehicle when the distance between the driver's mobile device and the vehicle is within a predetermined first distance value; transmitting, in the vehicle, a response to the Bluetooth connection request to the driver's mobile device; after the Bluetooth connection is established between the driver's mobile device and the vehicle, the driver's mobile device turns on a microphone, and the vehicle turns on a plurality of internal or externally installed speakers; transmitting sound wave signals from a microphone of the driver's mobile device through a plurality of speaker channels, wherein the plurality of speaker channels transmit sound wave signals of different frequencies; calculating, by the driver's mobile device, a distance between the driver's mobile device and the vehicle based on the sound wave signals received from the plurality of speaker channels; transmitting a control permission signal from the driver's mobile device to the vehicle when the calculated distance between the vehicle and the driver's mobile device is within a predetermined second distance value; and preparing to unlock a door or a trunk or to start the engine when the vehicle receives the control permission signal.

According to the present invention, the distance or each coordinate between the vehicle and the smartphone can be more precisely calculated using the arrival time and triangulation of the sound wave.

When triangulation using the sound wave reception time difference according to the present invention is used, even if there is a delay between Bluetooth, distance calculation is possible independently of the delay because the delay is not reflected in the distance calculation due to the above reasons.

In addition, since the calculation is performed using the arrival time of the sound waves generated by the three speakers, the relative position coordinates between the vehicle and the smartphone are also secured, so it is also possible to determine which part of the vehicle the user is closest to.

1 is a diagram illustrating the configuration of a system for determining a three-dimensional position of a driver using a TDoA value of a sound wave according to an embodiment of the present invention.
2 is a diagram illustrating an example of a method of calculating a distance or each coordinate between a vehicle and a driver's mobile device using arrival times of sound waves transmitted from a plurality of speaker channels according to the present invention.
3 is a diagram illustrating a method of calculating a distance or angular coordinates between a vehicle and a smartphone using the arrival time of sound waves and triangulation according to 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 can be naturally understood or made clearer by the following description, and the objects and effects of the present invention are not limited only by the following description.

The objects, features and advantages of the present invention will become more apparent from the following detailed description. In addition, in describing the present invention, when 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.

1 is a time difference of arrival (TDoA) value of a Bluetooth signal strength value (RSS, Received Signal Strength) transmitted from a vehicle and a sound wave (frequency of 2 to 24,000 Hz) transmitted from a speaker mounted on the vehicle according to the present invention; It shows the configuration of a system that uses the 3D position of the driver (or the 3D position of the driver's mobile device).

Hereinafter, it will be described as a Bluetooth signal, but it is revealed in advance that it can be applied to radio signals that can be used by a smart phone such as a Wi-Fi signal. In addition, the term “vehicle” hereinafter refers to a vehicle in which a smart key system is configured, and the smart key system controls at least three speakers and at least one Bluetooth or Wi-Fi module, and a speaker and Bluetooth/Wi-Fi signal, and a door or trunk of the vehicle. It is a system including a signal related to and a control unit for controlling vehicle starting, and is a smart control device for a vehicle that uses a mobile device to protect RSA.

According to the present invention, the distance between the location of the driver's mobile device (eg, smart phone) and the vehicle is measured using sound waves, and the vehicle is opened and closed by verifying it. Using sound waves, the location of the driver's mobile device can be measured much more accurately than Bluetooth or Wi-Fi signals. Because Bluetooth or Wi-Fi uses a high frequency of several GHz, whereas sound waves use a frequency of several kHz, which is about 1/1,000,000 of that, distance can be measured much more accurately.

According to the present invention, the distance between the location of the driver's mobile device and the vehicle is measured by using the time of arrival of sound wave signals generated from a plurality of speakers to reach the mobile device.

The speaker is located inside or outside the vehicle and transmits a sound wave signal toward the driver's mobile device.

In addition, Bluetooth signals can be used to transmit security information and commands, as well as share absolute time values between the vehicle and the driver's mobile device.

For example, the Bluetooth signal may include a car identification number, a current time, and an identification number of a randomly generated sound wave signal. The sound wave signal is transmitted for distance measurement, and an identification number may be encoded and included, and may be transmitted at a frequency in a band that is difficult for humans to hear.

FIG. 2 shows an example of a method of calculating a distance or each coordinate between a vehicle and a driver's mobile device using arrival times of sound waves transmitted from a plurality of speaker channels according to the present invention.

Referring to FIG. 2 , a smart key application (hereinafter referred to as an APP) is executed in the driver's mobile device 200 ( S200 ). Here, the mobile device is, for example, a smart phone, and any device capable of receiving a sound wave signal and processing the sound wave signal in a processor, such as a smart watch or a tablet, is possible.

The app executed in the driver's mobile device 200 may operate in the background, and periodically or aperiodically performs an action such as ping for Bluetooth connection with the vehicle.

When the distance between the driver's mobile device 200 and the vehicle 250 is within a predetermined distance (eg, 25 m), or when the driver's mobile device 200 and the vehicle 250 are connected via Bluetooth, the driver's mobile device ( 200) transmits the Bluetooth connection request to the vehicle 250 (S205). For example, a Bluetooth transceiver connected to the vehicle's controller (MCU) receives this request.

The vehicle 250 transmits a response to this to the driver's mobile device 200 (S210). For example, a Bluetooth transceiver connected to the vehicle's controller (MCU) transmits this response.

Through this, a Bluetooth connection is established between the driver's mobile device 200 and the vehicle 250 (established, S215).

The driver's mobile device 200 turns on the microphone (Mic ON, S220). This is only an example, and an operation of turning on another type of sensor capable of receiving a sound wave signal transmitted from a vehicle may be performed. Since the microphone is the most common example of a receiver for receiving a sound wave signal, the present invention will be described below based on the microphone.

When the Bluetooth connection is established in step S215, the vehicle 250 turns on a plurality of internally or externally installed speakers (Speaker On, S222). This speaker is an example of a device that transmits a sound wave signal, and may be an ultrasonic sensor, and the description of the speaker below may be applied to any device that transmits a sound wave signal.

The microphone of the driver's mobile device 200 is transmitted through a plurality of speaker channels of the vehicle 250 ( S230 ). For example, a plurality of speakers mounted on the vehicle transmit sound waves of different frequencies.

In this case, the sound wave signal transmitted from the speaker 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 in a band of 19 to 21 kHz, and is also referred to as an inaudible sound wave because people do not hear it well.

The driver's mobile device 200 calculates a distance between the driver's mobile device 200 and the vehicle 250 by receiving sound wave signals transmitted from a plurality of speakers ( S235 ). At this time, since the sound waves transmitted from each speaker channel have different frequencies, it is possible to distinguish when and from which channel the sound waves arrive through correlation. 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 a formula to find the area through the lengths of three sides of a triangle.

3 shows a method of calculating a distance or angular coordinates between a vehicle and a smartphone using the arrival time of sound waves and triangulation according to the present invention.

Referring to FIG. 3 , a method of calculating a distance will be described using three speakers installed on the left side of the vehicle as an example.

The position coordinates of the speaker channels attached to the vehicle are all known. Among them, relative coordinates are calculated based on one speaker and are called B(o, yb), C(0,0), D(0,yc). For example, it corresponds to speaker Ch 0, speaker Ch 4, and speaker Ch 2 of FIG. 1 . Let the location of the smartphone be A(Ax, Ay). Let the distance between AC be a, the distance between AB be a+b, the distance between AD be a+c, the distance between BC be d, and the distance between CD be e.

Here, d and e are constants as the distance between the speaker channels.

b and c are calculated through the following equation based on the difference in arrival time of sound waves transmitted from speaker Ch 0, speaker Ch 4, and speaker Ch 2.

[Equation 1]

Here, v is the speed of the sound wave, and t _chn is the arrival time of the sound wave of speaker Ch n.

By applying Heron's formula, the ratio of the areas of triangles ABC and ACD is expressed as the following equation.

[Equation 2]

Here, s1 is (a+(a+b)+d)/2, and s2 is (a+ (a+c)+e)/2.

Equation 2 is expanded and summarized as an equation for the unknown a, as follows.

[Equation 3]

However, here p=d ² -b ² and q=e ² -c ² .

A solution of Equation 3 is obtained as follows.

[Equation 4]

Coordinates (Ax, Ay) are obtained by combining the following equations based on the value of a obtained above.

[Equation 5]

Through this calculation, a total of two values of a and four coordinates of Ax and Ay can be obtained.

A and coordinates are determined according to a determination algorithm for determining based on the first arriving sound wave and channel numbers of a plurality of speakers according to the present invention.

This discrimination algorithm is based on the speaker channel where the first arriving sound wave is generated, and it is determined according to the channels corresponding to points B, C, and D corresponding to each first arriving sound wave as shown in Table 1 below.

[Table 1]

When the location of the driver's mobile device 200 is determined by the above method, the distance can be stably calculated even when the time synchronization between the driver's mobile device 200 and the vehicle 250 is unstable.

The time it takes for sound waves to actually be transmitted from each speaker according to the vehicle's ECU command is irregular. This is because the time data that can be collected from the driver's mobile device or the vehicle is the timing of the Bluetooth communication commanding the sound wave transmission from the driver's mobile device, so there is a time delay from the time when the actual sound wave transmission is completed. This is not a phenomenon that the speed of communication itself is delayed, but the delay it takes for the command to be transmitted from the driver's mobile device to the Bluetooth module. It is understood as a phenomenon that occurs because it cannot be assigned. This delay causes problems in the distance measurement algorithm because two devices with different time axes cannot be synchronized.

According to the present invention, when the same time axis is set based on the time when Bluetooth is first connected, the problem caused by the delay can be solved. Since sound waves are transmitted from each speaker channel of every vehicle with a single Bluetooth command, the absolute delay in all channels is the same. That is, there is no delay difference between sound waves transmitted from each speaker channel. Therefore, the different arrival times of sound waves for each speaker channel means different distances between each speaker channel and the driver's mobile device. Since each speaker channel transmits sound waves having frequencies in different regions, each arrival time can be distinguished through correlation.

Meanwhile, following step S235, if the distance between the vehicle 250 and the driver's mobile device 200 is within a predetermined distance value (eg, 2m) based on the calculated position coordinates of the driver's mobile device, the driver's The mobile device 200 transmits a control permission signal to the vehicle 250 (S240).

Since the driver's mobile device 200 directly transmits the control permission signal, the location of the driver's mobile device 200 cannot be forged unless the control permission signal is hacked, thereby preventing hacking. The control permission signal may be transmitted encrypted to prevent hacking.

As another example, in order to prevent the control permission signal from being hacked or forged, the vehicle may be set to open and close only when the driver directly applies an input (eg, a touch) to the door catcher (not shown).

Upon receiving the control permission signal, the vehicle 250 unlocks the door or trunk of the vehicle or prepares to start the vehicle ( S245 ). For example, when it is determined that the driver's mobile device is located inside the vehicle in a predetermined area within the vehicle after the door (or trunk) of the vehicle is opened, the driver boards and the vehicle starts is controlled.

The above-described preferred embodiments of the present invention are disclosed for the purpose of illustration, and those skilled in the art with ordinary knowledge for the present invention will be able to make various modifications, changes and additions within the spirit and scope of the present invention. should be considered to be within the scope of the above claims.

Those of ordinary skill in the art to which the present invention pertains, within the scope of not departing from the technical spirit of the present invention, various substitutions, modifications and changes are possible, so the present invention is described in the above-described embodiments and the accompanying drawings. not limited by

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.

Claims (7)

A method of calculating a distance or each coordinate between a vehicle 250 and a driver's mobile device 200 using the arrival time of sound waves transmitted from a plurality of speaker channels, the method comprising:
executing a smart key application on the driver's mobile device;
transmitting a Bluetooth connection request transmitted from the driver's mobile device to the vehicle when the distance between the driver's mobile device and the vehicle is within a predetermined first distance value;
transmitting, in the vehicle, a response to the Bluetooth connection request to the driver's mobile device;
after a Bluetooth connection is established between the driver's mobile device and the vehicle, the driver's mobile device turns on a microphone, and the vehicle turns on a plurality of internal or externally installed speakers;
transmitting sound wave signals from the driver's mobile device through a plurality of speaker channels, wherein the plurality of speaker channels transmit sound wave signals of different frequencies;
calculating, by the driver's mobile device, a distance between the driver's mobile device and the vehicle based on the sound wave signals received from the plurality of speaker channels;
transmitting a control permission signal from the driver's mobile device to the vehicle when the calculated distance between the vehicle and the driver's mobile device is within a predetermined second distance value; and
and preparing to unlock a door or a trunk or start the engine when the vehicle receives the control permission signal.
The method of claim 1,
The driver's mobile device
Distinguish when and from which channel the sound wave transmitted from the plurality of speaker channels arrives through correlation,
A method, characterized in that calculated through triangulation using Heron's formula based on the positions of at least three speaker channels based on ToA (Time of Arrival) or TDoA (Time Difference of Arrival).
3. The method of claim 2,
The app stores the location coordinates of the speaker channel attached to the vehicle in advance,
Relative coordinates are set based on the position of one speaker among the plurality of speaker channels that have received the sound wave, and the distance (a) between the speaker serving as the reference and the vehicle and the driver's mobile device based on Heron's formula Compute four solutions to the coordinates of
The location of the driver's mobile device and the distance between the vehicle and the driver's mobile device are calculated according to the discrimination algorithm in the following table, which is determined based on the channel numbers of the channels of the plurality of speakers and the channels of the sound waves that reach the microphone first among the plurality of speaker channels A method characterized by
[table]

The method of claim 1,
The method of claim 1 , wherein the vehicle door is set to open and close when a direct input is received from the vehicle door catcher.
The method of claim 1,
The driver's mobile device is one of a smart phone, a smart watch, and a tablet, and is a device capable of receiving a sound wave signal and processing the sound wave signal in a processor.
The method of claim 1,
The app running on the driver's mobile device may operate in a background, and transmits a Bluetooth request to the vehicle by periodically or aperiodically pinging.
The method of claim 1,
A speaker installed in the vehicle is an ultrasonic sensor that transmits inaudible sound waves in a band of 19 to 21 kHz.

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