JP7601157B2 - Digital Key System - Google Patents

Description

This paper relates to a digital key system and an in-vehicle system equipped with the digital key system, and in particular to a technology for vehicles that estimates the distance to a mobile terminal.

There is a known technology that uses radio waves transmitted by a radio to measure the distance to the radio. Patent Document 1 discloses a technology that measures the distance between a source radio and a destination radio based on the round-trip time of a packet. In the technology disclosed in Patent Document 1, the destination radio, i.e., the radio that replies with the packet, sets the time from receiving the packet to sending the reply packet to an integer multiple of the unit time. This eliminates the effect of the processing time in the destination radio.

Digital key systems are also being considered for use in shared cars, where multiple people share a single car. In a digital key system, a mobile terminal equipped with a radio stores information that allows the mobile terminal to be used as a digital key (hereinafter, digital key information). The mobile terminal is typically a smartphone, which obtains the digital key information from a server.

JP 2004-258009 A

In a digital key system, whether or not to allow operation of a vehicle using a smartphone is determined based on the distance of the smartphone from the vehicle, or its position, which is determined based on the distance from multiple reference points. Therefore, it is desirable to be able to accurately determine the distance of the smartphone from the vehicle.

When determining the distance from a vehicle to a smartphone, it is possible to use radio waves transmitted by the smartphone. The technology disclosed in Patent Document 1 also uses radio waves transmitted by a wireless device. However, the technology disclosed in Patent Document 1 requires each wireless device to measure an integer multiple of a unit time, so each wireless device needs to have a common counter. Therefore, it is difficult to apply this technology to a digital key system in which many smartphones can potentially serve as digital keys.

The present disclosure has been made based on this situation, and an object of the present disclosure is to provide a digital key system that can accurately estimate the distance to a mobile terminal.

The above object is achieved by a combination of features recited in the independent claims, and the subclaims define further advantageous specific examples. The reference characters in parentheses in the claims indicate a correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the disclosed technical scope.

One disclosure of a digital key system for achieving the above object is:
A mobile terminal (2) that can be used as a digital key for a vehicle (Hv);
An in-vehicle system (1, 101) that is mounted on a vehicle and communicates with a mobile terminal;
The in-vehicle system is a digital key system that estimates a distance of the mobile terminal from the vehicle based on radio waves transmitted from the mobile terminal, and determines whether or not to permit the mobile terminal to operate an in-vehicle device mounted on the vehicle based on the estimated distance,
The in-vehicle system includes a terminal-specific information acquisition unit (F4) that acquires terminal-specific information specific to the mobile terminal that affects the distance of the mobile terminal from the outside of the vehicle by wireless communication using an in-vehicle communication device (12, 13, 19) mounted on the vehicle;
a distance estimation unit (F5) that estimates a distance of the mobile terminal based on the terminal specific information acquired by the terminal specific information acquisition unit and distance information determined based on radio waves transmitted by the mobile terminal;
The terminal specific information includes an internal processing time from when the mobile terminal receives a radio wave transmitted by the in-vehicle system to when the mobile terminal transmits a response radio wave in response to the received radio wave,
the distance estimation unit estimates the distance to the mobile terminal based on the elapsed time (Tp) from when the in-vehicle system transmits a radio wave to the mobile terminal until the in-vehicle system receives a response radio wave, and the distance estimation unit estimates the distance to the mobile terminal based on the elapsed time and an internal processing time;
The mobile terminal stores terminal-specific information,
The terminal specific information acquisition unit acquires the internal processing time as the terminal specific information from the mobile terminal via wireless communication ;
The terminal specific information includes the transmission power of the radio waves transmitted by the mobile terminal.
the distance estimation unit uses a received power when a receiver included in the in-vehicle system receives radio waves transmitted from the mobile terminal as distance information, and estimates the distance to the mobile terminal based on a power attenuation rate of the received power relative to the transmission power;
The terminal specific information acquisition unit acquires the transmission power as the terminal specific information from a server (3) that stores the transmission power,
The server transmits authentication information to the in-vehicle system to authenticate that the mobile device is a digital key;
When transmitting the authentication information, the server also transmits the transmission power as terminal-specific information to the in-vehicle system .
In addition, one disclosure relating to a digital key system for achieving the above object is a mobile terminal (2) that can be used as a digital key for a vehicle (Hv);
An in-vehicle system (1, 101) that is mounted on a vehicle and communicates with a mobile terminal;
The in-vehicle system is a digital key system that estimates a distance of the mobile terminal from the vehicle based on radio waves transmitted from the mobile terminal, and determines whether or not to permit the mobile terminal to operate an in-vehicle device mounted on the vehicle based on the estimated distance,
The in-vehicle system includes a terminal-specific information acquisition unit (F4) that acquires terminal-specific information specific to the mobile terminal that affects the distance of the mobile terminal from the outside of the vehicle by wireless communication using an in-vehicle communication device (12, 13, 19) mounted on the vehicle;
a distance estimation unit (F5) that estimates a distance of the mobile terminal based on the terminal specific information acquired by the terminal specific information acquisition unit and distance information determined based on radio waves transmitted by the mobile terminal;
The terminal-specific information is the transmission power of radio waves transmitted by the mobile terminal,
the distance estimation unit uses a received power when a receiver included in the in-vehicle system receives radio waves transmitted from the mobile terminal as distance information, and estimates the distance to the mobile terminal based on a power attenuation rate of the received power relative to the transmission power;
The terminal specific information acquisition unit acquires the terminal specific information from a server (3) that stores the terminal specific information;
The server transmits authentication information to the in-vehicle system to authenticate that the mobile device is a digital key;
When transmitting the authentication information, the server also transmits the terminal-specific information to the in-vehicle system.

The in-vehicle system acquires terminal-specific information, and in order to estimate the distance to the mobile terminal, the in-vehicle system uses the terminal-specific information in addition to distance information determined based on the radio waves transmitted by the mobile terminal. Therefore, the distance to the mobile terminal can be estimated with higher accuracy than when the terminal-specific information is not taken into account.

FIG. 1 is a diagram showing the overall configuration of a digital key system. FIG. 2 is a diagram showing a configuration of a server 3. 2 is a block diagram showing a part of the internal configuration of the smartphone 2. FIG. 2 is a block diagram showing a configuration of a UWB communication unit 21. FIG. FIG. 1 is a block diagram illustrating a configuration of an in-vehicle system 1. 2 is a diagram illustrating an example of a mounting position of a UWB communication device 12. FIG. 2 is a block diagram showing the configuration of a smart ECU 11 and a UWB communication device 12. FIG. FIG. 11 is a diagram illustrating a round trip time Tp. 4 is a flowchart showing a process executed by the smart ECU 11 in a position estimation process. 10 is a flowchart showing a process executed by a terminal control unit 25 of the smartphone 2 in a position estimation process. A diagram showing the configuration of a smartphone 102 in a digital key system of a fourth embodiment. FIG. 13 is a diagram showing a configuration of an in-vehicle system 101 in a digital key system according to a fourth embodiment. FIG. 13 is a diagram showing a process executed by a terminal specific information acquisition unit F4 in the fourth embodiment. FIG. 23 is a diagram showing a process executed by a terminal specific information acquisition unit F4 in the eighth embodiment. FIG. 4 is a diagram showing the relationship between the times at which vehicle radio waves, reflected radio waves, and response radio waves are transmitted and received.

First Embodiment
Hereinafter, an embodiment of a digital key system according to the present disclosure will be described with reference to the drawings. As shown in Fig. 1, the digital key system according to the present disclosure includes an in-vehicle system 1 mounted on a vehicle Hv, a smartphone 2 which is a mobile terminal carried by a user of the vehicle Hv, and a server 3 installed outside the vehicle Hv.

[Overall Overview]
The smartphone 2 functions as a digital key for the in-vehicle system 1. In order for the smartphone 2 to function as a digital key, it is necessary for the smartphone 2 to transmit digital key information authenticated by the in-vehicle system 1 to the in-vehicle system 1. The digital key information is managed by the server 3.

By performing a specified process on the server 3, the smartphone 2 can obtain the digital key information from the server 3. In addition to having a function for communicating with the smartphone 2, the server 3 also communicates with the vehicle Hv. The server 3 transmits authentication information for authenticating the digital key information to the in-vehicle system 1, and the in-vehicle system 1 stores the authentication information.

The digital key information has an expiration date, and within the expiration date, the in-vehicle system 1 allows the smartphone 2 to operate the in-vehicle device. However, the condition for the in-vehicle system 1 to allow the smartphone 2 to operate the in-vehicle device is not limited to being able to authenticate the digital key information. The position or distance of the smartphone 2 relative to the vehicle Hv is also a condition. Therefore, the in-vehicle system 1 determines the distance or position of the smartphone 2. In order for the in-vehicle system 1 to determine the distance or position of the smartphone 2, the radio waves between the in-vehicle system 1 and the smartphone 2 are used.

Known methods of using radio waves to determine a position include a method that uses the propagation time of the radio waves and a method that uses the radio wave intensity. In the first embodiment, the propagation time is used.

To measure the propagation time with high accuracy, the in-vehicle system 1 and the smartphone 2 are configured to be able to carry out wireless communication using the UWB-IR (Ultra Wide Band - Impulse Radio) method (hereinafter, UWB communication). That is, the in-vehicle system 1 and the smartphone 2 are configured to be able to transmit and receive impulse-shaped radio waves (hereinafter, impulse signals) used in UWB communication. An impulse signal used in UWB communication is a signal with an extremely short pulse width (e.g., 2 nanoseconds) and a bandwidth of 500 MHz or more (i.e., ultra-wide bandwidth).

Frequency bands that can be used for UWB communication (hereinafter, UWB bands) include 3.2 GHz to 10.6 GHz, 3.4 GHz to 4.8 GHz, 7.25 GHz to 10.6 GHz, and 22 GHz to 29 GHz. Of these various frequency bands, the impulse signal in this embodiment is realized using radio waves in the 3.2 GHz to 10.6 GHz band. The frequency band used for the impulse signal may be appropriately selected depending on the country in which the vehicle Hv is used. The bandwidth of the impulse signal may be 500 MHz or more, and may be 1.5 GHz or more.

A variety of modulation methods can be used for UWB-IR communication, including pulse position modulation (PPM), which modulates at the position where a pulse is generated. Specifically, on-off modulation (OOK: On Off Keying), pulse width modulation (PWM: Pulse Width Modulation), pulse amplitude modulation (PAM: Pulse Amplitude Modulation), and pulse code modulation (PCM: Pulse Code Modulation) can be used. Note that the on-off modulation method is a method of expressing information (for example, 0 and 1) by the presence/absence of an impulse signal, while the pulse width modulation method is a method of expressing information by pulse width. The pulse amplitude modulation method is a method of expressing information by the amplitude of an impulse signal. The pulse code modulation method is a method of expressing information by a combination of pulses.

The in-vehicle system 1 and smartphone 2 of this embodiment are also configured to be able to implement wireless communication (hereinafter, BLE communication) conforming to the Bluetooth Low Energy (Bluetooth is a registered trademark) standard as the second communication method. The first communication method refers to the above-mentioned UWB communication. As the second communication method, various short-range wireless communication methods capable of setting the communication distance to about 10 meters, such as Wi-Fi (registered trademark) and ZigBee (registered trademark), other than Bluetooth Low Energy, can be adopted. The second communication method may be one that can provide a communication distance of, for example, several meters to several tens of meters. Hereinafter, in order to distinguish between UWB communication signals and BLE communication signals, wireless signals conforming to the BLE standard will also be referred to as BLE signals. Below, the specific configurations of the in-vehicle system 1, smartphone 2, and server 3 will be described in order.

[Configuration of Server 3]
First, a description will be given of the configuration of the server 3. As shown in Fig. 2, the server 3 is configured to include a wide area communication unit 31, a server storage unit 32, and a server control unit 33. The wide area communication unit 31 is a communication unit capable of wide area communication using a public communication line network.

The server storage unit 32 is a writable non-volatile memory, and stores the internal processing time Tb of the smartphone 2. The internal processing time Tb is the time required for the smartphone 2 to perform processing from receiving radio waves in which a response request signal is a baseband signal (hereinafter, response request radio waves) to transmitting radio waves in which a response signal in response to the response request signal is a baseband signal (hereinafter, response radio waves).

The internal processing time Tb is terminal-specific information that is model-dependent and individual-dependent. The server storage unit 32 stores the internal processing time Tb at least by model. Furthermore, for some individual devices, the internal processing time Tb may be stored by individual device.

The server storage unit 32 also stores digital key information and authentication information. The digital key information is information provided to the smartphone 2 used as a digital key for the vehicle Hv. The authentication information is information provided to the vehicle Hv to authenticate the digital key information.

The server control unit 33 controls the wide area communication unit 31. It controls the wide area communication unit 31 to transmit digital key information to the smartphone 2 and also transmit authentication information to the in-vehicle system 1. For example, when a user applies to use the vehicle Hv via the smartphone 2 and the application is accepted, the server control unit 33 transmits the digital key information and authentication information. The digital key information and authentication information may be pre-stored in the server storage unit 32, or the server control unit 33 may successively create them and store them in the server storage unit 32.

[Configuration of Smartphone 2]
Next, a description will be given of the configuration and operation of the smartphone 2. As shown in Fig. 3, the smartphone 2 includes a UWB communication unit 21, a BLE communication unit 22, a wide area communication unit 23, a terminal storage unit 24, a terminal control unit 25, and a notification unit 26. The terminal control unit 25 is connected to each of the UWB communication unit 21, the BLE communication unit 22, the wide area communication unit 23, the terminal storage unit 24, and the notification unit 26 so as to be able to communicate with each other.

The UWB communication unit 21 is a communication module for transmitting and receiving UWB impulse signals, and is a terminal communication unit that communicates with the UWB communication device 12. The UWB communication unit 21 generates a modulated signal while electrically processing, such as modulating a baseband signal input from the terminal-side control unit 25, and transmits this modulated signal by UWB communication. The modulated signal is a signal obtained by modulating transmission data using a predetermined modulation method (for example, PCM modulation method). The modulated signal is a signal sequence (hereinafter, pulse sequence signal) in which multiple impulse signals are arranged at time intervals corresponding to the transmission data. In addition, when the UWB communication unit 21 receives a series of modulated signals (i.e., pulse sequence signals) consisting of multiple impulse signals transmitted from the in-vehicle system 1, it demodulates the received signal and restores the data before modulation. Then, it outputs the received data to the terminal-side control unit 25.

The BLE communication unit 22 is a communication module for performing BLE communication. The BLE communication unit 22 receives a BLE signal transmitted from the vehicle Hv and provides it to the terminal-side control unit 25, and also modulates data input from the terminal-side control unit 25 and transmits it to the vehicle Hv.

The wide area communication unit 23 is a communication unit capable of wide area communication using a public communication line network. The wide area communication unit 23 can communicate with the wide area communication unit 31. The terminal storage unit 24 is a writable non-volatile memory. The terminal storage unit 24 stores digital key information transmitted from the server 3.

The terminal-side control unit 25 is realized by using a computer equipped with, for example, a CPU, RAM, and ROM. When received data indicating a response request signal is input from the UWB communication unit 21, a baseband signal corresponding to a response signal responding to the response request signal is generated, and this baseband signal is output to the UWB communication unit 21. The baseband signal output by the terminal-side control unit 25 to the UWB communication unit 21 is modulated by the UWB communication unit 21 and transmitted as a response radio wave.

The notification unit 26 is a display unit and/or a speaker. Various notifications are output from the notification unit 26.

Figure 4 shows the hardware configuration of the UWB communication unit 21. The hardware configuration of the UWB communication unit 21 is that of a general communication device. The UWB communication unit 21 has an antenna 211, which receives the response request radio wave described above. The response request radio wave received by the antenna 211 is amplified and filtered by the RF unit 212, and then passes through the RF switch 213 and is input to the analog receiving unit 214. The RF switch 213 is a switch that inputs the signal from the antenna 211 to the analog receiving unit 214 and inputs the signal from the analog transmitting unit 219 to the RF unit 212.

The analog receiving unit 214 demodulates the input analog signal. The demodulated analog signal is converted to a digital signal by the AD conversion circuit 215 and then input to the digital receiving unit 216. The digital receiving unit 216 digitally demodulates the input digital signal. The demodulated digital signal is input to the terminal-side control unit 25.

The terminal-side control unit 25 generates a response signal. This response signal is input to the digital transmission unit 217. The digital transmission unit 217 digitally modulates the input response signal. The signal digitally modulated by the digital transmission unit 217 is input to the DA conversion circuit 218 and converted into an analog signal. This analog signal is analog-modulated by the analog transmission unit 219. The analog-modulated signal passes through the RF switch 213 and is input to the RF unit 212, where it is amplified and then transmitted from the antenna 211 as a response radio wave.

In this configuration, the time it takes for a signal to be transmitted inside the UWB communication unit 21 and the time it takes for the terminal-side control unit 25 to process the signal is the internal processing time Tb. The internal processing time Tb varies depending on the individual device and the model due to the influence of factors such as the clock accuracy of the digital receiving unit 216 and the digital transmitting unit 217.

[In-vehicle system 1]
The in-vehicle system 1 realizes a passive entry passive start system (hereinafter referred to as the PEPS system) that performs predetermined vehicle control according to the position of the smartphone 2 by performing wireless communication with the smartphone 2 using radio waves in a predetermined frequency band.

For example, if the in-vehicle system 1 is able to confirm that the smartphone 2 is within a preset operating area for the vehicle Hv, it executes control such as locking and unlocking the doors based on a user operation on a door button 14, which will be described later. Also, if the in-vehicle system 1 is able to confirm through wireless communication with the smartphone 2 that the smartphone 2 is within the vehicle cabin, it executes engine start control based on a user operation on a start button 15, which will be described later.

The operating area is an area in which the in-vehicle system 1 executes a predetermined vehicle control, such as locking or unlocking the doors, based on the presence of the smartphone 2 within the area. For example, the vicinity of the driver's door, the vicinity of the passenger door, and the vicinity of the trunk door are set as the operating area. The vicinity of the door refers to an area within a predetermined operating distance from the outer door handle. The outer door handle refers to a gripping member provided on the outer surface of the door for opening and closing the door. The operating distance that defines the size of the operating area is, for example, 0.7 m. Of course, the operating distance may be 1 m or 1.5 m. The operating distance is often set to be less than 2 m from the viewpoint of crime prevention.

As shown in FIG. 5, the in-vehicle system 1 includes a smart ECU 11, multiple UWB communication devices 12, a BLE communication device 13, a door button 14, a start button 15, an engine ECU 16, a body ECU 17, and a wide area communication device 19. The in-vehicle system 1 also includes an in-vehicle actuator 171, an in-vehicle sensor 172, and the like. Note that ECU in the component names is an abbreviation for Electronic Control Unit, and refers to an electronic control device.

The smart ECU 11 is an ECU that performs vehicle control such as locking and unlocking doors and starting the engine by performing UWB communication with the smartphone 2. The smart ECU 11 is connected to the engine ECU 16 and the body ECU 17 so as to be able to communicate with each other via a communication network established within the vehicle. The smart ECU 11 is also electrically connected to the UWB communication device 12, the BLE communication device 13, the door button 14, and the start button 15. The smart ECU 11 is realized, for example, using a computer. That is, the smart ECU 11 includes a CPU 111, a flash memory 112, a RAM 113, an I/O 114, and a bus line connecting these components.

The flash memory 112 stores a program (hereinafter, a position estimation program) for causing the computer to function as the smart ECU 11. The position estimation program may be stored in a non-transitive tangible storage medium. Execution of the position estimation program by the CPU 111 corresponds to execution of a method corresponding to the position estimation program. Details of the smart ECU 11 will be described later.

The UWB communication device 12 is a communication module for performing UWB communication with the smartphone 2. The UWB communication device 12 is an in-vehicle communication device provided for estimating the position of the smartphone 2. Each UWB communication device 12 is connected to the smart ECU 11 via a dedicated communication line or an in-vehicle network so as to be able to communicate with each other. The operation of each UWB communication device 12 is controlled by the smart ECU 11. A unique communication device number is set to each UWB communication device 12. The communication device number is information equivalent to a terminal ID for the smartphone 2. The communication device number functions as information for identifying multiple UWB communication devices 12. The mounting positions and electrical configurations of the multiple UWB communication devices 12 will be described separately below.

The BLE communication device 13 is a communication module for implementing BLE communication. The BLE communication device 13 is connected to the smart ECU 11 so as to be able to communicate with each other. The BLE communication device 13 receives a BLE signal transmitted from the smartphone 2 and provides it to the smart ECU 11. The BLE communication device 13 also modulates data input from the smart ECU 11 and wirelessly transmits it to the smartphone 2. The BLE communication device 13 is attached to any position of the vehicle Hv. For example, the BLE communication device 13 is attached to the instrument panel, the upper end of the windshield, the B-pillar, the rocker section, etc. There may be one BLE communication device 13 or multiple BLE communication devices 13.

The door button 14 is a button that allows the user to unlock and lock the doors of the vehicle Hv. The door button 14 is provided, for example, on each door handle of the vehicle Hv. When the door button 14 is pressed by the user, it outputs an electrical signal indicating this to the smart ECU 11. The door button 14 corresponds to a configuration that allows the smart ECU 11 to accept an unlock instruction and a lock instruction from the user. Note that a touch sensor can also be used as a configuration for accepting at least one of the user's unlock instruction and lock instruction. The touch sensor is a device that detects that the user is touching the door handle.

The start button 15 is a push switch that allows the user to start the drive source (e.g., an engine) of the vehicle Hv. When the user pushes the start button 15, it outputs an electrical signal indicating this to the smart ECU 11. Note that, as an example here, the vehicle Hv is a vehicle equipped with an engine as a power source, but is not limited to this. The vehicle Hv may be an electric vehicle or a hybrid vehicle. If the vehicle Hv is a vehicle equipped with a motor as a drive source, the start button 15 is a switch for starting the drive motor.

The engine ECU 16 is an ECU that controls the operation of the engine mounted on the vehicle Hv. For example, when the engine ECU 16 receives a start instruction signal from the smart ECU 11 instructing the engine to start, it starts the engine.

The body ECU 17 is an ECU that controls the on-board actuators 171 based on requests from the smart ECU 11. The body ECU 17 is communicatively connected to various on-board actuators 171 and various on-board sensors 172. The on-board actuators 171 here are, for example, door lock motors that constitute the locking mechanisms of the doors, and seat actuators for adjusting the seat position. The on-board sensors 172 here are, for example, courtesy switches arranged for each door. The courtesy switches are sensors that detect the opening and closing of the doors. The body ECU 17 locks and unlocks each door by outputting a predetermined control signal to a door lock motor provided in each door of the vehicle Hv based on a request from, for example, the smart ECU 11.

[Installation position and electrical configuration of each UWB communication device 12]
The in-vehicle system 1 of this embodiment includes a right front communication device 12A, a left front communication device 12B, a right rear communication device 12C, and a left rear communication device 12D as the UWB communication device 12, as shown in FIG. 6. The right front communication device 12A is disposed, for example, in the upper region of the A-pillar on the right side of the vehicle. The A-pillar is the first pillar from the front in the vehicle Hv. The A-pillar is also called the front pillar. The upper region of the pillar refers to the region that is the upper half of the pillar. The upper region of the pillar also includes the upper end of the pillar. The left front communication device 12B is disposed, for example, in the upper region of the A-pillar on the left side of the vehicle. The right rear communication device 12C is disposed in the upper region of the C-pillar on the right side of the vehicle. The left rear communication device 12D is disposed in the upper region of the C-pillar on the left side of the vehicle. The C-pillar is the third pillar from the front. The C-pillar is also called the rear pillar.

In a configuration in which distance is measured using the propagation time of radio waves as in this embodiment, it is preferable that each UWB communication device 12 is disposed in a position that provides good visibility to both the inside and outside of the vehicle cabin. Examples of places that provide good visibility to both the inside and outside of the vehicle cabin include the interior ceiling and various pillars. In other words, the arrangement of the various UWB communication devices 12 as described above corresponds to one example of an arrangement in which each UWB communication device 12 is disposed in a position that provides good visibility to both the inside and outside of the vehicle cabin.

The installation position of each UWB communication device 12 in the vehicle Hv may be expressed as a point in a three-dimensional orthogonal coordinate system with an arbitrary point on the vehicle as the reference point (in other words, the origin). Here, as an example, it is expressed as a point on a three-dimensional coordinate system (hereinafter, vehicle three-dimensional coordinate system) with the center of the front wheel axle as the origin and the X, Y, and Z axes perpendicular to each other. The X axis forming the vehicle three-dimensional coordinate system is parallel to the vehicle width direction and has the right side of the vehicle as the positive direction. The Y axis is parallel to the vehicle front-rear direction and has the front of the vehicle as the positive direction. The Z axis is parallel to the vehicle height direction and has the upper part of the vehicle as the positive direction. The center of the three-dimensional coordinate system can be changed as appropriate, for example, to the center of the rear wheel axle. Of course, as another embodiment, the mounting position of each UWB communication device 12 may be expressed in polar coordinates. Communication device position data indicating the installation position of each UWB communication device 12 is stored in the flash memory 112. The installation location of each UWB communication device 12 needs to be stored in association with the communication device number.

As shown in FIG. 7, each of the multiple UWB communication devices 12 includes a transmitter 310, a receiver 320, and a round trip time measurement unit 330. The transmitter 310 generates an impulse signal while electrically processing the baseband signal input from the smart ECU 11, such as modulating the signal, and emits the impulse signal as a radio wave. The transmitter 310 is realized, for example, using a modulation circuit 311 and a transmission antenna 312.

The round trip time measurement unit 330 is a timer that measures the elapsed time (hereinafter, round trip time Tp) from when the transmitting unit 310 transmits an impulse signal to when the receiving unit 320 receives the impulse signal. The timing at which the transmitting unit 310 transmits the impulse signal is determined by the input of a transmission notification signal. The timing at which the receiving unit 320 receives the impulse signal is determined by the input of a reception notification signal. In other words, the round trip time measurement unit 330 measures the time from when the modulation circuit 311 outputs a transmission notification signal to when the demodulation circuit 322 outputs a reception notification signal. As shown in FIG. 8, the round trip time Tp corresponds to the sum of the round trip propagation time Ta and the internal processing time Tb in the smartphone 2.

The round trip time measurement unit 330 measures the elapsed time since the transmission unit 310 transmitted the impulse signal by counting the clock signal input from a clock oscillator (not shown). The round trip time measurement unit 330 stops counting when a reception notification signal is input or when a predetermined upper limit value is reached, and outputs the count value to the smart ECU 11. In other words, it reports the round trip time Tp to the smart ECU 11. Note that when the reporting of the round trip time Tp to the smart ECU 11 is completed, the count value of the round trip time measurement unit 330 returns to 0 (i.e., is reset).

When the round trip time measurement unit 330 completes the measurement of the round trip time Tp, it provides the round trip time Tp to the smart ECU 11. The round trip time measurement unit 330 is realized, for example, by using an IC. Note that, here, the UWB communication device 12 is shown in a form in which a transmission antenna (i.e., the transmission antenna 312) and a reception antenna (i.e., the reception antenna 321) are separately provided, but this is not limited to this. The UWB communication device 12 may be configured to share one antenna element for transmission and reception using a directional coupler. In addition, the modulation circuit 311 and the demodulation circuit 322 may be built into an IC that provides the function of the round trip time measurement unit 330. In other words, the UWB communication device 12 may be realized by using one antenna and one dedicated IC having various circuit functions.

[Functions of Smart ECU 11]
The smart ECU 11 executes the above-mentioned position estimation program to provide functions corresponding to various functional blocks shown in Fig. 7. That is, the smart ECU 11 includes, as functional blocks, a vehicle information acquisition unit F1, a communication processing unit F2, an authentication processing unit F3, a terminal specific information acquisition unit F4, a distance estimation unit F5, a position estimation unit F6, and a vehicle control unit F7.

The vehicle information acquisition unit F1 acquires various information indicating the state of the vehicle Hv (hereinafter, vehicle information) from sensors, ECUs (e.g., the body ECU 17), switches, etc. mounted on the vehicle Hv. Examples of vehicle information include the open/closed state of the doors, the locked/unlocked state of each door, whether the door button 14 has been pressed, and whether the start button 15 has been pressed. The vehicle information acquisition unit F1 also identifies the current state of the vehicle Hv based on the various information described above. For example, the vehicle information acquisition unit F1 determines that the vehicle Hv is parked when the engine is off and all the doors are locked. Of course, the conditions for determining that the vehicle Hv is parked may be designed as appropriate, and a variety of determination conditions can be applied.

Note that obtaining information indicating the locked/unlocked state of each door corresponds to determining the locked/unlocked state of each door and detecting the user's operation to lock/unlock the door. Also, obtaining electrical signals from the door button 14 and the start button 15 corresponds to detecting the user's operation on these buttons. In other words, the vehicle information obtaining unit F1 corresponds to a configuration that detects the user's operation on the vehicle Hv, such as opening and closing the door, pressing the door button 14, pressing the start button 15, etc. The vehicle information hereinafter also includes the user's operation on the vehicle Hv. In addition, the types of information included in the vehicle information are not limited to those described above. The vehicle information also includes the shift position detected by a shift position sensor (not shown) and the detection result of a brake sensor that detects whether the brake pedal is depressed. The operating state of the parking brake can also be included in the vehicle information.

The communication processing unit F2 is configured to cooperate with the UWB communication device 12 and the BLE communication device 13 to transmit and receive data to and from the smartphone 2. For example, the communication processing unit F2 generates data addressed to the smartphone 2 and outputs it to the BLE communication device 13. This causes a signal corresponding to the desired data to be transmitted as radio waves. The communication processing unit F2 also receives data from the smartphone 2 that is received by the BLE communication device 13. As a more preferred aspect of this embodiment, the wireless communication between the smart ECU 11 and the smartphone 2 is configured to be encrypted. A variety of encryption methods can be used, such as the method specified by Bluetooth.

In this embodiment, the smart ECU 11 and the smartphone 2 are configured to encrypt data communication for authentication and the like to improve security, but this is not limited to the above. In another embodiment, the smart ECU 11 and the smartphone 2 may be configured to perform data communication without encryption.

The communication processing unit F2 recognizes that a user is present in the vicinity of the vehicle Hv based on the establishment of BLE communication with the smartphone 2. The communication processing unit F2 also acquires from the BLE communication device 13 the terminal ID of the smartphone 2 to which the BLE communication device 13 is communicatively connected. With this configuration, even if the vehicle Hv is a vehicle shared by multiple users, the smart ECU 11 can identify users present in the vicinity of the vehicle Hv based on the terminal ID of the smartphone 2 to which the BLE communication device 13 is communicatively connected.

The communication processing unit F2 also acquires data from the smartphone 2 received by the UWB communication device 12. In addition, the communication processing unit F2 generates data addressed to the smartphone 2 and outputs it to the UWB communication device 12. This causes a pulse sequence signal corresponding to the desired data to be wirelessly transmitted. Furthermore, the communication processing unit F2 causes an impulse signal to be transmitted from any UWB communication device 12 based on an instruction from the position estimation unit F6.

The authentication processing unit F3 cooperates with the BLE communication device 13 to perform a process of confirming that the communication partner is the user's smartphone 2 (in other words, authentication). The communication for authentication is encrypted and performed via the BLE communication device 13. In other words, the authentication process is performed by encrypted communication. The authentication process itself may be performed using various methods such as a challenge-response method. A detailed description thereof will be omitted here. The timing at which the authentication processing unit F3 performs the authentication process may be, for example, the timing at which a communication connection between the BLE communication device 13 and the smartphone 2 is established. The authentication processing unit F3 may be configured to perform the authentication process at a predetermined cycle while the BLE communication device 13 and the smartphone 2 are connected for communication. Also, the encrypted communication for the authentication process may be performed when a predetermined user operation on the vehicle Hv is triggered, such as when the start button 15 is pressed by the user.

In the Bluetooth standard, the establishment of a communication connection between the BLE communication device 13 and the smartphone 2 means that the communication partner of the BLE communication device 13 is the smartphone 2 that has been registered in advance. Therefore, the smart ECU 11 may be configured to determine that authentication of the smartphone 2 has been successful based on the establishment of a communication connection between the BLE communication device 13 and the smartphone 2.

The terminal-specific information acquisition unit F4 acquires the internal processing time Tb transmitted from outside the vehicle Hv and input to the communication processing unit F2. In this embodiment, as described below, the internal processing time Tb is transmitted from the smartphone 2 via UWB communication. The terminal-specific information acquisition unit F4 stores the acquired internal processing time Tb in a predetermined storage unit. This storage unit is the flash memory 112 here.

The distance estimation unit F5 causes each UWB communication device 12 to transmit and receive impulse signals to and from the smartphone 2 in a predetermined order, and acquires the round trip time Tp from each UWB communication device 12 via the communication processing unit F2. It also acquires the internal processing time Tb from the flash memory 112. The round trip time Tp is a time that includes the propagation time of the response radio wave transmitted by the smartphone 2, and is distance information for determining the distance between the UWB communication device 12 and the smartphone 2. The distance estimation unit F5 estimates the distance between the UWB communication device 12 and the smartphone 2 from the round trip time Tp and the internal processing time Tb.

The position estimation unit F6 estimates the position of the smartphone 2 based on the distance from each UWB communication device 12 to the smartphone 2 estimated by the distance estimation unit F5. The position estimation process for estimating the position of the smartphone 2, including the process executed by the position estimation unit F6, will be described separately below.

The vehicle control unit F7 is configured to cooperate with the body ECU 17 and the like to execute vehicle control according to the position of the smartphone 2 (in other words, the user) and the state of the vehicle Hv when the authentication processing unit F3 has been successful in authenticating the smartphone 2. The state of the vehicle Hv is determined by the vehicle information acquisition unit F1. The position of the smartphone 2 is determined by the position estimation unit F6.

For example, when the vehicle Hv is parked, the smartphone 2 is outside the vehicle cabin, and the door button 14 is pressed by the user, the vehicle control unit F7 cooperates with the body ECU 17 to unlock the door lock mechanism. Also, for example, when the position estimation unit F6 determines that the smartphone 2 is inside the vehicle cabin and detects that the start button 15 has been pressed by the user, the vehicle control unit F7 cooperates with the engine ECU 16 to start the engine. In this way, the vehicle control unit F7 is basically configured to execute vehicle control according to the user's position and the state of the vehicle Hv, triggered by a user operation on the vehicle Hv. However, some of the vehicle controls that the vehicle control unit F7 can execute may be executed automatically according to the user's position, without requiring a user operation on the vehicle Hv.

[Position Estimation Processing]
Next, the position estimation process executed by the smart ECU 11 and the terminal-side control unit 25 of the smartphone 2 will be described with reference to the flowcharts shown in Fig. 9 and Fig. 10. The position estimation process is a process for estimating the position of the smartphone 2. The position estimation process is performed at a predetermined position estimation period in a state in which a connection between the BLE communication device 13 and the BLE communication unit 22 of the smartphone 2 is established. The position estimation period is, for example, 200 milliseconds. Of course, the position estimation period may be 100 milliseconds or 300 milliseconds.

Figure 9 shows the position estimation process executed by the smart ECU 11. Of the steps shown in Figure 9, steps (hereinafter, "step" will be omitted) S11 and S12 are executed by the communication processing unit F2, S13 to S16 are executed by the terminal-specific information acquisition unit F4, S17 to S21 are executed by the distance estimation unit F5, and S22 is executed by the position estimation unit F6. The process shown in Figure 9 is executed for each UWB communication device 12. Figure 10 shows the position estimation process executed by the terminal-side control unit 25 of the smartphone 2.

First, in S11, it is determined whether or not a connection is being established between the UWB communication device 12 and the smartphone 2. If the determination result in S11 is YES, the process proceeds directly to S17, and if the determination result is NO, the process proceeds to S12.

In S12, the UWB communication device 12 transmits a connection establishment signal to the vicinity of the vehicle Hv. In S13, it is determined whether a response radio wave transmitted by the UWB communication unit 21 of the smartphone 2 in response to the connection establishment signal has been received within a certain period of time. If the determination result in S13 is NO, the process shown in FIG. 9 is terminated.

If the result of the determination in S13 is YES, a connection is established based on the received response radio wave, and then the process proceeds to S14. In S14, it is determined whether or not a signal indicating the internal processing time Tb has been received within a certain time after the response radio wave has been received. If the result of the determination in S14 is YES, the process proceeds to S15. In S15, the internal processing time Tb is stored in a predetermined storage unit such as the flash memory 112. If the result of the determination in S14 is NO, the process proceeds to S16. In S16, if the internal processing time Tb of the smartphone 2 is already stored in the storage unit, it is determined to use the internal processing time Tb required for the calculation in S19. This is because the internal processing time Tb may be transmitted from the smartphone 2 and stored through communication with another UWB communication device 12. If the internal processing time Tb is not stored in the storage unit, it is determined to use an initial value as the internal processing time Tb required for the calculation in S19.

In S17, a response request radio wave is transmitted from the UWB communication device 12. In S18, a response radio wave transmitted from the smartphone 2 in response to the response request radio wave is received. In S19, the round trip time Tp is acquired. Specifically, the round trip time measurement unit 330 measures the round trip time Tp from the transmission time of the response request radio wave and the reception time of the response radio wave. This round trip time Tp is acquired from the round trip time measurement unit 330.

In S20, the internal processing time Tb stored in S15 or determined in S16 is subtracted from the round trip time Tp acquired in S19, and the subtracted value is divided by 2 to calculate the propagation time Ta from the UWB communication device 12 to the smartphone 2. If the round trip time measurement unit 330 does not receive a response radio wave, which is an impulse signal, even after a predetermined response waiting time has elapsed since the impulse signal was transmitted, it may provide the smart ECU 11 with a value indicating that the propagation time Ta is unknown. The response waiting time may be set to a value, such as 33 nanoseconds, that assumes a state in which the user is sufficiently far away (for example, 10 m or more) from the vehicle Hv.

In S21, the propagation time Ta calculated in S20 is multiplied by the speed of light to calculate the distance from the UWB communication device 12 to the smartphone 2.

S22 is executed when distances are calculated for three or more UWB communication devices 12. In S22, the position of the smartphone 2 is estimated based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2.

The installation position of each UWB communication device 12 can be determined by using the communication device position data stored in the flash memory 112. The position can be estimated based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2 using the principle of triangulation. As a method for estimating the position using the installation position of each UWB communication device 12 and the distance to the smartphone 2, various algorithms can be adopted, such as the least squares method, the Newton-Raphson method, and the minimum mean square estimate (MMSE).

The position of the smartphone 2 estimated as described above (hereinafter, the terminal position) is referenced by the vehicle control unit F7 and the like. For example, it is determined whether or not the terminal position is within the operating area or the vehicle interior. If the terminal position is within the operating area, the vehicle control unit F7 executes unlocking or locking of the doors based on the determination result. Also, if the terminal position is within the vehicle interior, the vehicle control unit F7 starts the driving source for driving the vehicle based on the determination result.

Next, FIG. 10 will be described. The process shown in FIG. 10 is also executed at the same position estimation period as FIG. 9 when a BLE communication connection is established. The process shown in FIG. 10 is also executed for each UWB communication device 12. The smartphone 2 can obtain the number of UWB communication devices 12 provided in the in-vehicle system 1 through BLE communication.

In S31, it is determined whether or not a connection with the UWB communication device 12 is being established. If the determination result in S31 is YES, proceed to S38. If the determination result in S31 is NO, proceed to S32. In S32, it is determined whether or not a connection establishment signal has been received. If the determination result in S32 is NO, the process shown in FIG. 10 is temporarily terminated. If the determination result in S32 is YES, proceed to S33.

In S33, it is determined whether the internal processing time Tb has been transmitted to the in-vehicle system 1. If the determination result in S33 is NO, the process proceeds to S34. In S34, a response radio wave is transmitted. In the following S35, the internal processing time Tb is determined, and the determined internal processing time Tb is stored in the flash memory 112. Note that if the internal processing time Tb has already been stored in the flash memory 112, the process of S35 can be omitted. An example of a case in which the internal processing time Tb has already been stored in the flash memory 112 is when the internal processing time Tb has been measured and stored in the flash memory 112 at the time of shipment. There may also be a case in which the internal processing time Tb has already been determined in order to provide it to an in-vehicle system 1 equipped in another vehicle Hv.

The internal processing time Tb is the time from receiving the connection establishment signal to transmitting a response radio wave. In S36, a signal indicating the internal processing time Tb determined in S35 is transmitted to the UWB communication device 12. When this signal is received by the UWB communication device 12, the determination result in S14 becomes YES. Note that since it is only necessary to transmit the internal processing time Tb to the in-vehicle system 1, the transmission and reception of the signal indicating the internal processing time Tb may be performed by BLE communication.

If the determination result in S33 is YES, the process proceeds to S37. The processing of S37 is the same as S34, and a response radio wave is transmitted. In S38, it is determined whether or not a response request radio wave transmitted from the in-vehicle system 1 by executing S17 has been received. If the determination result in S38 is NO, S38 is executed again. If the determination result in S38 is YES, the process proceeds to S39. In S39, a response radio wave is transmitted. The response radio wave transmitted here is received in S18.

Summary of the First Embodiment
When estimating the distance to the smartphone 2 based on the round trip time Tp, an error in the internal processing time Tb of the smartphone 2 significantly affects the error in the distance. Moreover, the internal processing time Tb is model-dependent and individual-dependent. However, in the first embodiment, the smartphone 2 measures the internal processing time Tb (S35) and transmits the measured internal processing time Tb to the in-vehicle system 1 (S36). The in-vehicle system 1 receives the internal processing time Tb and stores it in the flash memory 112 (S15).

Then, when calculating the propagation time Ta, the internal processing time Tb stored in the flash memory 112 is used. Therefore, the propagation time Ta can be calculated with high accuracy. As a result, the distance can be estimated with high accuracy, and the position of the smartphone 2 can be estimated with high accuracy based on the accurate distance.

Second Embodiment
Next, a second embodiment will be described. In the following description of the second embodiment, elements having the same reference numerals as those used up to that point are the same as those in the previous embodiment unless otherwise specified. Furthermore, when only a part of the configuration is described, the previously described embodiment can be applied to the other parts of the configuration.

The second embodiment is a modified example of the first embodiment. In the first embodiment, the internal processing time Tb measured by the smartphone 2 is transmitted from the smartphone 2 to the in-vehicle system 1. However, the smartphone 2 may transmit the internal processing time Tb to the in-vehicle system 1 and also to the server 3 from the wide area communication unit 23. In this way, the internal processing time Tb for each smartphone 2 is accumulated in the server storage unit 32.

The terminal-specific information acquisition unit F4 may then acquire the internal processing time Tb of the smartphone 2 with which a connection has been established from the server 3.

Furthermore, the terminal-specific information acquisition unit F4 can also acquire the internal processing time Tb from the server 3 before establishing a connection, as described below. As described above, the server 3 transmits authentication information for authenticating the digital key information provided to the smartphone 2 to the in-vehicle system 1. When transmitting this authentication information, the internal processing time Tb of the smartphone 2 may also be transmitted at the same time.

Third Embodiment
Furthermore, when focusing on the model dependency of the internal processing time Tb, it is not necessary to individually obtain the internal processing time Tb from the smartphone 2. Therefore, for a plurality of models of smartphones 2, the internal processing times Tb for each model may be collectively obtained from a management site of the smartphone 2 manufacturer or the like and stored in the server storage unit 32. The in-vehicle system 1 obtains the model of the smartphone 2 by communicating with the smartphone 2, and obtains from the server 3 the internal processing time Tb of the smartphone 2 with which a connection is currently established.

Fourth Embodiment
In the first embodiment, an example has been described in which the internal processing time Tb is measured by the smartphone 2. In this fourth embodiment, the in-vehicle system 1 estimates the internal processing time Tb in a state in which it is detected that the smartphone 2 is in a known position.

Figure 11 shows the configuration of the smartphone 102 in the digital key system of the fourth embodiment. The smartphone 102 differs from the smartphone 2 of the previous embodiments in that it has an NFC communication unit 124. Figure 12 shows the configuration of the in-vehicle system 101 in the digital key system of the fourth embodiment. The in-vehicle system 101 differs from the in-vehicle system 1 of the previous embodiments in that it has an NFC communication unit 115.

The NFC communication units 124 and 115 can communicate with each other through NFC (Near Field Communication). NFC communication can also be called near-field communication. The NFC communication units 124 and 115 are an example of a near-field communication unit. The communication distance of NFC communication is approximately 10 cm at most. However, when performing NFC communication, the user usually touches the smartphone 102 to the surface of the communication device of the communication partner. Therefore, the communication distance during actual communication is shorter than 10 cm and is almost constant.

Therefore, the propagation time Ta when the NFC communication unit 115 and the NFC communication unit 124 communicate can be calculated without communication. This propagation time Ta is stored in the flash memory 112.

The NFC communication unit 115 can be installed in various positions. In this example, it is assumed that multiple NFC communication units 115 are provided, one of which is housed in the door handle. The NFC communication unit 124 provided in the smartphone 102 transmits digital key information to the NFC communication unit 115 housed in the door handle. At this time, the authentication processing unit F3 executes the authentication process.

In addition, one of the NFC communication units 115 can be housed in the start button 15 inside the vehicle. When the smartphone 102 is held over the door button and the digital key information is authenticated by NFC communication, the in-vehicle system 101 can start operation in the same way as when the start button 15 is pressed.

Figure 13 shows the process executed by the terminal-specific information acquisition unit F4 in the fourth embodiment. The process shown in Figure 13 is executed periodically, for example, with an execution period similar to that of the position estimation process.

In S41, it is determined whether or not NFC communication has been established. If the determination result in S41 is NO, the process shown in FIG. 13 is terminated. If the determination result in S41 is YES, the process proceeds to S42. When proceeding to S42, the position of the smartphone 102 can be estimated to be a known position in contact with the NFC communication unit 115. Since the installation position of the UWB communication device 12 is also known, when the smartphone 102 is in a known position, the distance between the smartphone 102 and the UWB communication device 12 is also known.

In S42, it is determined whether the internal processing time Tb of the smartphone 102 is stored in the flash memory 112. If the determination result in S42 is NO, i.e., if the internal processing time Tb of the smartphone 102 is stored in the flash memory 112, the process shown in FIG. 13 is also terminated.

If the determination result in S42 is YES, i.e., the internal processing time Tb of the smartphone 102 is not stored in the flash memory 112, the process proceeds to S43. In S43, a response request radio wave is transmitted from one pre-set UWB communication device 12, with the positioning signal being a baseband signal. In S44, a response radio wave is received, with the positioning signal being a baseband signal transmitted from the smartphone 102 in response to the positioning signal. In S45, the round trip time Tp measured by the round trip time measurement unit 330 is obtained by transmitting and receiving this positioning signal.

In S46, Tp-2Ta is calculated from the round trip time Tp acquired in S45 and the propagation time Ta stored in the flash memory 112 in association with the NFC communication unit 115, and the internal processing time Tb is calculated. In S47, the internal processing time Tb calculated in S46 is stored in the flash memory 112.

In the fourth embodiment, the internal processing time Tb is stored in the flash memory 112 in this manner. Therefore, in the position estimation process, the smart ECU 11 omits S11 to S16 of the process shown in FIG. 9 and executes S17 and onward. At that time, in S20, if the internal processing time Tb is stored in the flash memory 112, the internal processing time Tb is used to calculate the propagation time Ta. If the internal processing time Tb is not stored, an initial value is used to calculate the propagation time Ta.

Since the smart ECU 11 executes this processing, the terminal-side control unit 25 of the smartphone 102 executes only S38 and S39 in the processing shown in FIG. 10 while the connection is established.

Summary of the Fourth Embodiment
In the fourth embodiment, since NFC communication is established, it is possible to determine that the position of the smartphone 102 is in a known position. Then, when the smartphone 102 is in a known position, a round trip time Tp from when the UWB communication device 12 transmits a response request radio wave until the UWB communication device 12 receives the response radio wave transmitted by the smartphone 102 is acquired (S45). From this round trip time Tp and a propagation time Ta determined in advance, an internal processing time Tb can be calculated and stored (S45, S46). In this way, by storing the internal processing time Tb for each smartphone 102, it is possible to accurately estimate the position of the smartphone 102 when the smartphone 102 is not in a known position by a position estimation process.

Fifth Embodiment
The fifth embodiment is a modification of the fourth embodiment. In the fourth embodiment, the in-vehicle system 101 includes the NFC communication unit 115, and determines that the smartphone 102 is in a known position by establishing NFC communication.

However, the position of the smartphone 102 may be determined by providing an on-board camera and analyzing images from the on-board camera. In this way, there is no need to install a communication unit at a location that is to be considered as a known position, and there are fewer restrictions on the known position compared to when an NFC communication unit 115 is installed.

The known position may be the same as that in the fourth embodiment, or may be, for example, a position outside the vehicle where the B-pillar is in contact with the vehicle, or the center of the steering wheel. The known position is preferably a position that has good visibility of radio waves between the UWB communication device 12.

The owner of the smartphone 102 can also be instructed via the smartphone 102 to place the smartphone 102 at a known position. The instruction can be given by voice, image, or voice and image. This is particularly effective when various positions are set as known positions. This instruction may also be given even if the known position is only a position in contact with the NFC communication unit 124.

After receiving the instruction, if it is determined that the smartphone 102 is not in a known location, the smartphone 102 is notified that it is not in a known location via the BLE communication device 13 or the UWB communication device 12. When the smartphone 102 is notified that it is not in a known location, it outputs that fact from the notification unit 26.

In addition, regardless of whether or not an instruction is given to position smartphone 102 at a known location, the result of the determination as to whether smartphone 102 is at a known location may be notified to smartphone 102.

Sixth Embodiment
The sixth embodiment is also a modification of the fourth embodiment. As with the NFC communication unit 115, a wireless charging device that wirelessly charges the smartphone 102 is one with which the smartphone 102 comes into contact. The smartphone 102 placed on the wireless charging device can be said to be in a known position. Therefore, the known position can be the position where the smartphone 102 is placed on the wireless charging device.

In this case, it can be determined that the smartphone 102 is in a known position because the wireless charging device is charging. Note that the wireless charging device can determine that charging is in progress, for example, from the power supply efficiency.

Seventh Embodiment
In the above embodiments, the distance from the UWB communication device 12 to the smartphone 2 is estimated based on the propagation time Ta. However, it is also possible to estimate the distance between the smartphone 2 and the receiver provided in the in-vehicle system 1 based on the received power when the in-vehicle system 1 receives the radio waves transmitted from the smartphone 2.

When estimating distance accurately based on the received power, it is necessary to accurately determine the transmission power of the radio waves transmitted by the smartphone 2. Therefore, instead of the internal processing time Tb described in the previous embodiments, the terminal-specific information acquisition unit F4 acquires, as terminal-specific information, the transmission power when the UWB communication unit 21 of the smartphone 2 transmits the response radio waves.

The distance estimation unit F5 calculates the power attenuation rate of the received power received by the UWB communication device 12 with respect to this transmission power. Of the transmission power and the received power, the received power changes depending on the distance, so the received power is the distance information. Since the power attenuation rate is proportional to the distance, the distance is estimated from the power attenuation rate. After the distance is estimated, the position of the smartphone 2 can be estimated in the same manner as in the first embodiment.

The modified example described in the second embodiment can also be applied when estimating the position of the smartphone 2 based on the power decay rate. That is, the transmission power may be stored in the server 3. The terminal-specific information acquisition unit F4 may also acquire the transmission power of the smartphone 2 with which a connection has been established from the server 3. The in-vehicle system 1 may acquire the transmission power at the same time as acquiring the authentication information. The modified examples described in the third to sixth embodiments can also be applied when estimating the position of the smartphone 2 based on the power decay rate.

Eighth Embodiment
In the eighth embodiment, either the smartphone 2 or 102 can be used. Also, either the in-vehicle system 1 or 101 can be used. In the following, the smartphone 2 and the in-vehicle system 1 will be described.

In the eighth embodiment, as in the fourth embodiment, the smart ECU 11 estimates the internal processing time Tb of the smartphone 2. In the fourth embodiment, the smartphone 102 had to be in a known position. In contrast, in the eighth embodiment, the smartphone 2 does not have to be in a known position.

First, an overview of the eighth embodiment will be described. The eighth embodiment utilizes the property that the smartphone 2 has of reflecting radio waves. If the housing of the smartphone 2 is made of metal, the housing will reflect radio waves. Even if the housing is not made of metal, there is metal inside the smartphone 2. Therefore, the smartphone 2 will reflect radio waves. In the eighth embodiment, the time difference between the time when the in-vehicle system 1 receives the reflected radio waves and the time when it receives the response radio waves is calculated.

Figure 14 shows the process executed by the terminal-specific information acquisition unit F4 in the eighth embodiment. The process shown in Figure 14 is executed periodically when a connection is established by BLE communication or UWB communication and the internal processing time Tb of the smartphone 2 is not stored in the flash memory 112. When a connection is established by BLE communication or UWB communication, the smartphone 2 is in the vicinity of the vehicle or inside the vehicle. The vicinity of the vehicle means outside the vehicle and within the communication range of BLE communication or UWB communication.

In S51, it is determined whether or not the smartphone 2 is near the vehicle. In other words, it is determined whether or not the smartphone 2 is not inside the vehicle Hv. The position of the smartphone 2 here does not require high accuracy. Therefore, the position of the smartphone 2 used in the determination in S51 can be estimated as follows. For example, the internal processing time Tb is set as an initial value, and three distances are calculated based on the propagation time that can be calculated by transmitting and receiving radio waves, and the position can be estimated from the three distances. Also, a camera may be provided, and the position of the smartphone 2 may be estimated by analyzing images captured by the camera.

If the determination result in S51 is NO, the process shown in FIG. 14 is terminated. On the other hand, if the determination result in S51 is YES, the process proceeds to S52. In other words, if it is determined that the smartphone 2 is not inside the vehicle but is in the vicinity of the vehicle, the process proceeds to S52 and onwards. The reason that S52 and onwards are not executed when the smartphone 2 is inside the vehicle is that there may be various radio wave reflecting objects inside the vehicle, and it is difficult to determine whether the reflected radio waves are caused by reflection by the smartphone 2.

In S52, a predetermined radio wave (hereinafter, vehicle radio wave) is transmitted from one of the UWB communication devices 12. As described above, the smartphone 2 reflects the radio wave. In S53, it is determined whether or not a reflected radio wave generated by reflection of the vehicle radio wave has been received. Vehicle radio waves are reflected by various radio wave reflecting objects such as metals. In addition, there may be various radio wave reflecting objects in the vicinity of the vehicle Hv. Therefore, it is not possible to know whether the reflected radio wave is a reflected radio wave generated by reflection of the vehicle radio wave by the smartphone 2.

However, S53 judges YES if a reflected radio wave is received for the first time. This is because the smartphone 2 should be near the vehicle, and if the area around the vehicle Hv is open, the reflected radio wave received first can be assumed to have been reflected by the smartphone 2. Note that it is possible to determine that the received radio wave is a reflected radio wave and not a response radio wave by demodulating and decoding the radio wave to extract the baseband signal. In S54, the reception time at which the reflected radio wave was received (hereinafter, the reflected radio wave reception time) is determined. The reflected radio wave reception time is an example of reflected radio wave information.

In S55, it is determined whether or not a response radio wave has been received. Whether or not the received radio wave is a response radio wave can be determined by demodulating and decoding the received radio wave to extract the baseband signal. If the result of the determination in S55 is NO, S55 is executed repeatedly. Note that a timeout period is set in both S55 and the above-mentioned S53, and when the timeout period is reached, the process shown in FIG. 14 ends. If the result of the determination in S55 is YES, the process proceeds to S56. In S56, the reception time at which the response radio wave was received (hereinafter, the response radio wave reception time) is determined. The response radio wave reception time is an example of response radio wave information.

In S57, it is determined whether the reflected radio wave is a radio wave reflected from smartphone 2. This determination is made by comparing the reflected radio wave reception time with the response radio wave reception time. If the reflected radio wave reception time is the same as or later than the received radio wave reception time, the reflected radio wave is determined not to be a radio wave reflected from smartphone 2. Also, even if the reflected radio wave reception time is earlier than the received radio wave reception time, if the difference between the reflected radio wave reception time and the response radio wave reception time is greater than the expected internal processing time Tb, it is also determined not to be a reflected radio wave from smartphone 2. If it is determined that the reflected radio wave is not from smartphone 2, that is, if the determination result in S57 is NO, the processing shown in FIG. 14 is terminated.

If the determination result in S57 is YES, the process proceeds to S58. In S58, the reception time difference between the reflected radio wave reception time determined in S54 and the response radio wave reception time determined in S56 is calculated. Figure 15 shows the relationship between the times at which the vehicle radio wave, the reflected radio wave, and the response radio wave are transmitted and received. As shown in Figure 15, the difference between time t5, which is the response radio wave reception time, and time t4, which is the reflected radio wave reception time, corresponds to the internal processing time Tb. Therefore, in S59, the reception time difference is stored in flash memory 112 as internal processing time Tb.

After storing the internal processing time Tb in this manner, in the position estimation process, the smart ECU 11 omits S11 to S16 of the process shown in FIG. 9 and executes S17 and onwards. At that time, in S20, if the internal processing time Tb is stored in the flash memory 112, the internal processing time Tb is used to calculate the propagation time Ta. If the internal processing time Tb is not stored, the initial value is used to calculate the propagation time Ta. While the connection is established, the terminal-side control unit 25 of the smartphone 2 executes only S38 and S39 in the process shown in FIG. 10.

[Summary of the Eighth Embodiment]
In the eighth embodiment, the time difference between the reflected radio wave reception time and the response radio wave reception time is set as the internal processing time Tb of the smartphone 2. Therefore, even if the smartphone 2 is not in a known position, the internal processing time Tb can be calculated.

In the eighth embodiment, if it is determined that the smartphone 2 is located near the vehicle, the reflected radio wave reception time and the response radio wave reception time are determined. This makes it possible to prevent the reflected radio wave reception time from being determined for a reflected radio wave that was not reflected by the smartphone 2.

Ninth embodiment
The ninth embodiment is a modification of the eighth embodiment. In the eighth embodiment, the distance from the UWB communication device 12 to the smartphone 2 is estimated based on the propagation time Ta. In contrast, in the ninth embodiment, the distance between the smartphone 2 and the receiver provided in the in-vehicle system 1 is estimated based on the received power when the in-vehicle system 1 receives the radio waves transmitted from the smartphone 2.

In the ninth embodiment, the terminal-specific information acquisition unit F4 determines the received power of the reflected radio wave as the reflected radio wave information. Then, the distance between the UWB communication device 12 and the smartphone 2 is estimated from the transmission power of the vehicle radio wave, which is the transmitted radio wave, and the received power of the reflected radio wave. Note that the transmission power of the vehicle radio wave is assumed to have been acquired in advance by measurement or the like.

The received power of the reflected radio waves decreases as the round-trip distance between the UWB communication device 12 and the smartphone 2 increases. It is known that radio wave power attenuates as the cube of the distance, so if the transmission power of the vehicle radio waves and the received power of the reflected radio waves are known, the round-trip distance between the UWB communication device 12 and the smartphone 2, and further the distance between the UWB communication device 12 and the smartphone 2, can be estimated.

Furthermore, the terminal-specific information acquisition unit F4 acquires the received power when the UWB communication device 12 receives the response radio wave transmitted by the smartphone 2. The transmission power of the response radio wave transmitted by the smartphone 2 can be estimated by multiplying the received power of the response radio wave by a coefficient determined from the distance between the UWB communication device 12 and the smartphone 2. The terminal-specific information acquisition unit F4 acquires the transmission power of this response radio wave as terminal-specific information.

The distance estimation unit F5 calculates the power attenuation rate of the received power received by the UWB communication device 12 during the position estimation process, relative to the transmission power acquired by the terminal-specific information acquisition unit F4. The received power is distance information. The distance is estimated from the power attenuation rate.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modified examples described below are also included in the technical scope of the present disclosure, and further, various modifications other than those described below can be implemented without departing from the gist of the present disclosure. For example, the various modified examples described below can be implemented in appropriate combinations as long as no technical contradiction occurs.
<Modification 1>
In the embodiment, the smartphones 2 and 102 are exemplified as the mobile terminal. However, as the mobile terminal, a tablet terminal, a wearable terminal, or the like, other than the smartphones 2 and 102, may also be used.

<Modification 2>
The in-vehicle systems 1 and 101 of the embodiments include four UWB communication devices 12. However, the number of UWB communication devices 12 may be three or more.

<Modification 3>
In the embodiment, three or more distances from the UWB communication device 12 to the smartphones 2 and 102 are estimated, and then the positions of the smartphones 2 and 102 are estimated based on the distances. However, it is also possible to determine whether or not to operate the in-vehicle device based on the distance of the smartphones 2 and 102 without estimating the positions.

1: In-vehicle system 2: Smartphone (mobile terminal) 3: Server 11: Smart ECU 12: UWB communication device 13: BLE communication device 14: Door button 15: Start button 16: Engine ECU 17: Body ECU 19: Wide area communication device 21: UWB communication unit 22: BLE communication unit 23: Wide area communication unit 24: Terminal memory unit 25: Terminal side control unit 26: Notification unit 31: Wide area communication unit 32: Server memory unit 33: Server control unit 101: In-vehicle system 102: Smartphone 111: CPU 112: Flash memory 113: RAM 114: I/O 115: NFC communication unit 124: NFC communication unit 330: Round trip time measurement unit F1: Vehicle information acquisition unit F2: Communication processing unit F3: Authentication processing unit F4: Terminal specific information acquisition unit F5: Distance estimation unit F6: Position estimation unit F7: Vehicle control unit Hv: Vehicle Ta: Propagation time Tb: Internal processing time Tp: Round trip time

Claims (5)

A mobile terminal (2) that can be used as a digital key for a vehicle (Hv);
An in-vehicle system (1, 101) that is mounted on the vehicle and communicates with the mobile terminal,
the in-vehicle system is a digital key system that estimates a distance of the mobile terminal to the vehicle based on radio waves transmitted from the mobile terminal, and determines whether or not to permit operation of an in-vehicle device mounted on the vehicle by the mobile terminal based on the estimated distance,
The in-vehicle system includes a terminal-specific information acquisition unit (F4) that acquires terminal-specific information specific to the mobile terminal that affects the distance of the mobile terminal from the outside of the vehicle by wireless communication using an in-vehicle communication device (12, 13, 19) mounted on the vehicle;
a distance estimation unit (F5) that estimates a distance to the mobile terminal based on the terminal specific information acquired by the terminal specific information acquisition unit and distance information determined based on radio waves transmitted by the mobile terminal,
the terminal specific information includes an internal processing time from when the portable terminal receives a radio wave transmitted by the in-vehicle system to when the portable terminal transmits a response radio wave in response to the received radio wave,
the distance estimation unit determines an elapsed time (Tp) from when the in-vehicle system transmits a radio wave to the mobile terminal until the in-vehicle system receives the response radio wave as distance information, and estimates a distance to the mobile terminal based on the elapsed time and the internal processing time;
The mobile terminal stores the terminal-specific information,
the terminal specific information acquisition unit acquires the internal processing time as the terminal specific information from the mobile terminal via wireless communication ;
Further, the terminal specific information includes a transmission power of a radio wave transmitted by the mobile terminal,
the distance estimation unit determines a reception power when a radio wave transmitted from the mobile terminal is received by a receiver included in the in-vehicle system as the distance information, and estimates the distance of the mobile terminal based on a power attenuation rate of the reception power with respect to the transmission power;
The terminal specific information acquisition unit acquires the transmission power as the terminal specific information from a server (3) that stores the transmission power;
the server transmits authentication information to the in-vehicle system for the in-vehicle system to authenticate that the mobile terminal is the digital key;
When transmitting the authentication information, the server also transmits the transmission power as the terminal-specific information to the in-vehicle system . 2. The digital key system according to claim 1,
A digital key system in which the internal processing time is measured by the mobile terminal. A mobile terminal (2) that can be used as a digital key for a vehicle (Hv);
An in-vehicle system (1, 101) that is mounted on the vehicle and communicates with the mobile terminal,
the in-vehicle system is a digital key system that estimates a distance of the mobile terminal to the vehicle based on radio waves transmitted from the mobile terminal, and determines whether or not to permit operation of an in-vehicle device mounted on the vehicle by the mobile terminal based on the estimated distance,
The in-vehicle system includes a terminal-specific information acquisition unit (F4) that acquires terminal-specific information specific to the mobile terminal that affects the distance of the mobile terminal from the outside of the vehicle by wireless communication using an in-vehicle communication device (12, 13, 19) mounted on the vehicle;
a distance estimation unit (F5) that estimates a distance to the mobile terminal based on the terminal specific information acquired by the terminal specific information acquisition unit and distance information determined based on radio waves transmitted by the mobile terminal,
the terminal-specific information is a transmission power of a radio wave transmitted by the mobile terminal,
the distance estimation unit determines a reception power when a radio wave transmitted from the mobile terminal is received by a receiver included in the in-vehicle system as the distance information, and estimates the distance of the mobile terminal based on a power attenuation rate of the reception power with respect to the transmission power ;
The terminal specific information acquisition unit acquires the terminal specific information from a server (3) that stores the terminal specific information,
the server transmits authentication information to the in-vehicle system for the in-vehicle system to authenticate that the mobile terminal is the digital key;
A digital key system, wherein the server transmits the terminal specific information to the in-vehicle system when transmitting the authentication information . 4. The digital key system according to claim 3 ,
The mobile terminal includes a wide area communication unit (23) that communicates with the server, and transmits the terminal-specific information from the wide area communication unit to the server;
The digital key system includes a server storage unit (32) that stores the terminal-specific information transmitted from the mobile terminal. 4. The digital key system according to claim 3 ,
The server includes a server storage unit (32) that stores the terminal-specific information for each model of the mobile terminal.

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