Digital Key System

Abstract

To provide a digital key system that can accurately estimate the distance to a mobile terminal.SOLUTION: A digital key system includes a mobile terminal that can be used as a digital key for a vehicle, and an on-vehicle system that is installed on the vehicle and communicates with the mobile terminal. The on-vehicle system estimates the distance of the mobile terminal to the vehicle based on radio waves transmitted by the mobile terminal, and determines whether to permit the mobile terminal to operate an on-vehicle device installed on the vehicle based on the estimated distance. The on-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, and a distance estimation unit F5 that estimates the 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 the radio waves transmitted by the mobile terminal.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a digital key system and an in-vehicle system equipped with the digital key system, and in particular to a technology for a vehicle that estimates the distance to a mobile terminal. [Background technology]

[0002] There is a known technology for measuring the distance to a wireless device by using radio waves transmitted by the wireless device. Patent Document 1 discloses a technology for measuring the distance between a source wireless device and a destination wireless device based on the round-trip time of a packet. In the technology disclosed in Patent Document 1, the destination wireless device, i.e., the wireless device that replies with a packet, sets the time from receiving a packet to transmitting a reply packet to an integer multiple of the unit time. This eliminates the effect of the processing time in the destination wireless device.

[0003] Digital key systems are also being considered for use in car sharing, where multiple people share a single car. Digital key systems store information (hereinafter, "digital key information") that enables a mobile terminal equipped with a wireless device to be used as a digital key. The mobile terminal is typically a smartphone, and the smartphone obtains the digital key information from a server. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-258009 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a digital key system, whether or not to permit operation of a vehicle using a smartphone is determined based on the distance of the smartphone from the vehicle or its position 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.

[0006] When determining the distance from the vehicle to the 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.

[0007] The present disclosure has been made based on this situation, and its object is to provide a digital key system that can accurately estimate the distance to a mobile terminal. M The purpose is to provide. [Means for solving the problem]

[0008] The above object is achieved by the 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 specific means described in the following embodiment as one aspect, and do not limit the disclosed technical scope.

[0009] 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 in 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 internal processing time from when the mobile terminal receives the radio wave transmitted by the in-vehicle system to when it transmits the response radio wave in response to the received radio wave. Includes , the distance estimation unit estimates the distance of the portable terminal based on the elapsed time (Tp) from when the in-vehicle system transmits a radio wave to the portable terminal until the in-vehicle system receives a response radio wave, and the elapsed time and the internal processing time are used as distance information; The mobile terminal stores terminal-specific information, The terminal specific information acquisition unit acquires terminal specific information Internal processing time as acquired from a mobile device via wireless communication death, 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 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 in 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.

[0010] The in-vehicle system acquires the 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, thereby enabling the distance to the mobile terminal to be estimated more accurately than in the case where the terminal-specific information is not taken into consideration. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a digital key system. [Diagram 2] FIG. 2 is a diagram showing a configuration of a server 3. [Diagram 3] 2 is a block diagram showing a part of the internal configuration of the smartphone 2. FIG. [Figure 4] 2 is a block diagram showing a configuration of a UWB communication unit 21. FIG. [Diagram 5] FIG. 1 is a block diagram illustrating a configuration of an in-vehicle system 1. [Figure 6] FIG. 2 is a diagram for explaining an example of an installation position of a UWB communication device 12. [Figure 7] 2 is a block diagram showing the configuration of a smart ECU 11 and a UWB communication device 12. FIG. [Figure 8] FIG. 1 is a diagram for explaining a round trip time Tp. [Figure 9] 6 is a flowchart showing a process executed by the smart ECU 11 in a position estimation process. [Figure 10]13 is a flowchart showing a process executed by a terminal control unit 25 of the smartphone 2 in the position estimation process. [Figure 11] FIG. 13 is a diagram showing a configuration of a smartphone 102 in a digital key system according to a fourth embodiment. [Figure 12] FIG. 11 is a diagram showing a configuration of an in-vehicle system 101 in a digital key system according to a fourth embodiment. [Figure 13] FIG. 13 is a diagram showing a process executed by a terminal specific information acquisition unit F4 in the fourth embodiment. [Figure 14] FIG. 23 is a diagram showing a process executed by a terminal specific information acquisition unit F4 in the eighth embodiment. [Figure 15] 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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.

[0014] [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 to be authenticated by the in-vehicle system 1 to the in-vehicle system 1. The digital key information is managed by the server 3.

[0015] By performing a predetermined process on the server 3, the smartphone 2 can obtain the digital key information from the server 3. The server 3 has a function for communicating with the smartphone 2, and 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.

[0016] 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 authentication of 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, radio waves between the in-vehicle system 1 and the smartphone 2 are used.

[0017] Known methods of using radio waves to determine a position include a method of using radio wave propagation time, a method of using radio wave intensity, etc. In the first embodiment, the propagation time is used.

[0018] In order to measure the propagation time with high accuracy, the in-vehicle system 1 and the smartphone 2 are configured to be able to perform wireless communication (hereinafter, UWB communication) using the UWB-IR (Ultra Wide Band - Impulse Radio) method. 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. The impulse signal used in UWB communication is a signal that has an extremely short pulse width (e.g., 2 nanoseconds) and a bandwidth of 500 MHz or more (i.e., ultra-wide bandwidth).

[0019] Frequency bands available 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.

[0020] A variety of modulation methods can be used for UWB-IR communications, 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 on-off modulation is a method of expressing information (for example, 0 and 1) by the presence / absence of an impulse signal, while pulse width modulation is a method of expressing information by pulse width. Pulse amplitude modulation is a method of expressing information by the amplitude of an impulse signal. Pulse code modulation is a method of expressing information by a combination of pulses.

[0021] In addition, the in-vehicle system 1 and the smartphone 2 of this embodiment are 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-distance 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 capable of providing a communication distance of, for example, about several meters to several tens of meters. Hereinafter, in order to distinguish between a signal of UWB communication and a signal of BLE communication, a wireless signal conforming to the BLE standard is also referred to as a BLE signal. Hereinafter, the specific configurations of the in-vehicle system 1, the smartphone 2, and the server 3 will be described in order.

[0022] [Server 3 configuration] First, we will explain 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.

[0023] 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 processing from when the smartphone 2 receives radio waves in which a response request signal is a baseband signal (hereinafter, response request radio waves) until it transmits radio waves in which a response signal in response to the response request signal is a baseband signal (hereinafter, response radio waves).

[0024] The internal processing time Tb is terminal-specific information that is type-dependent and individual-dependent. The internal processing time Tb is stored at least by type in the server storage unit 32. Furthermore, for some individual devices, the internal processing time Tb may be stored by individual device.

[0025] 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.

[0026] The server control unit 33 controls the wide area communication unit 31. The wide area communication unit 31 is controlled to transmit the digital key information to the smartphone 2 and also transmits the authentication information to the in-vehicle system 1. The server control unit 33 transmits the digital key information and the authentication information, for example, when a user applies to use the vehicle Hv via the smartphone 2 and the application is accepted. The digital key information and the authentication information may be stored in the server storage unit 32 in advance, or the server control unit 33 may successively create the information and store it in the server storage unit 32.

[0027] [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 side control unit 25, and a notification unit 26. The terminal side 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.

[0028] 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 the 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. Furthermore, 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.

[0029] 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 the modulated data to the vehicle Hv.

[0030] 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.

[0031] The terminal-side control unit 25 is realized by using a computer including, for example, a CPU, a RAM, and a ROM. When reception data indicating a response request signal is input from the UWB communication unit 21, the terminal-side control unit 25 generates a baseband signal corresponding to a response signal responding to the response request signal, and outputs the baseband signal 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.

[0032] The notification unit 26 is one or both of a display unit and a speaker. Various notifications are output from the notification unit 26.

[0033] 4 shows the hardware configuration of UWB communication unit 21. The hardware configuration of UWB communication unit 21 is the hardware configuration of a general communication device. UWB communication unit 21 has antenna 211, which receives the above-mentioned response request radio wave. The response request radio wave received by antenna 211 is amplified and filtered by RF unit 212, and then passes through RF switch 213 and is input to analog receiving unit 214. RF switch 213 is a switch that inputs the signal from antenna 211 to analog receiving unit 214 and inputs the signal from analog transmitting unit 219 to RF unit 212.

[0034] The analog receiving unit 214 demodulates the input analog signal. The demodulated analog signal is converted into a digital signal by an AD conversion circuit 215 and then input to a 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.

[0035] The terminal side control unit 25 generates a response signal. This response signal is input to a 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 a DA conversion circuit 218 and converted into an analog signal. This analog signal is analog-modulated by an analog transmission unit 219. The analog-modulated signal passes through an RF switch 213, is input to an RF unit 212, is amplified by 212, and is then transmitted from an antenna 211 as a response radio wave.

[0036] In such a configuration, the time it takes for a signal to be transmitted inside UWB communication unit 21 and the time it takes for terminal-side control unit 25 to process the signal is internal processing time Tb. Internal processing time Tb varies depending on the individual device and the model due to the influence of clock accuracy of digital receiving unit 216 and digital transmitting unit 217, etc.

[0037] [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.

[0038] For example, when the in-vehicle system 1 confirms that the smartphone 2 is within a preset operating area for the vehicle Hv, it executes control such as locking or unlocking the doors based on a user operation on a door button 14, which will be described later. Also, when the in-vehicle system 1 confirms that the smartphone 2 is inside the vehicle cabin through wireless communication with the smartphone 2, it executes engine start control based on a user operation on a start button 15, which will be described later.

[0039] 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 a range 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 smaller than 2 m from the viewpoint of crime prevention.

[0040] 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 names of the components is an abbreviation for Electronic Control Unit, and means an electronic control device.

[0041] 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 built in 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, by 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.

[0042] 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.

[0043] 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.

[0044] The BLE communicator 13 is a communication module for performing BLE communication. The BLE communicator 13 is connected to the smart ECU 11 so as to be capable of mutual communication. The BLE communicator 13 receives a BLE signal transmitted from the smartphone 2 and provides it to the smart ECU 11. The BLE communicator 13 also modulates data input from the smart ECU 11 and wirelessly transmits the data to the smartphone 2. The BLE communicator 13 is attached to any position of the vehicle Hv. For example, the BLE communicator 13 is attached to an instrument panel, an upper end of the windshield, a B-pillar, a rocker section, or the like. There may be one or more BLE communicators 13.

[0045] The door button 14 is a button for a 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 a user, it outputs an electric signal indicating that to the smart ECU 11. The door button 14 corresponds to a configuration for the smart ECU 11 to receive an unlock instruction and a lock instruction from the user. Note that a touch sensor can also be used as a configuration for receiving at least one of the unlock instruction and the lock instruction from the user. The touch sensor is a device that detects that the user is touching the door handle.

[0046] 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 electric signal indicating that 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.

[0047] The engine ECU 16 is an ECU that controls the operation of an engine mounted in the vehicle Hv. For example, when the engine ECU 16 receives a start instruction signal from the smart ECU 11 to instruct the engine to start, the engine ECU 16 starts the engine.

[0048] The body ECU 17 is an ECU that controls the on-vehicle actuators 171 based on a request from the smart ECU 11. The body ECU 17 is communicably connected to various on-vehicle actuators 171 and various on-vehicle sensors 172. The on-vehicle actuators 171 here are, for example, door lock motors that constitute the locking mechanisms of the doors, and seat actuators for adjusting the seat positions. The on-vehicle 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, for example, a request from the smart ECU 11.

[0049] [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.

[0050] 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. Examples of places that provide good visibility to both the inside and outside of the vehicle include the interior ceiling and various pillars. In other words, the above-mentioned arrangement of the various UWB communication devices 12 corresponds to an 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.

[0051] 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 of the vehicle as a 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 having mutually orthogonal X, Y, and Z axes. 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 appropriately changed, 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 position of each UWB communication device 12 may be stored in association with the communication device number.

[0052] 7, each of the 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, for example modulating, a baseband signal input from the smart ECU 11, and emits the impulse signal as a radio wave. The transmitter 310 is realized, for example, by using a modulation circuit 311 and a transmission antenna 312.

[0053] The round trip time measurement unit 330 is a timer that measures the elapsed time from when the transmitting unit 310 transmits an impulse signal until when the receiving unit 320 receives the impulse signal (hereinafter, round trip time Tp). The timing at which the transmitting unit 310 transmits the impulse signal is specified by the input of a transmission notification signal. The timing at which the receiving unit 320 receives the impulse signal is specified by the input of a reception notification signal. That is, the round trip time measurement unit 330 measures the time from when the modulation circuit 311 outputs a transmission notification signal until 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.

[0054] The round trip time measurement unit 330 counts the clock signal input from a clock oscillator (not shown) to measure the elapsed time since the transmission unit 310 transmitted the impulse signal. 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, the round trip time measurement unit 330 reports the round trip time Tp to the smart ECU 11. When the report 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).

[0055] When the measurement of the round trip time Tp is completed, the round trip time measurement unit 330 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, in the present embodiment, the UWB communication device 12 has a transmitting antenna (i.e., the transmitting antenna 312) and a receiving antenna (i.e., the receiving antenna 321) separately provided, but is not limited to this. The UWB communication device 12 may be configured to share one antenna element for transmitting and receiving by using a directional coupler. Also, the modulation circuit 311 and the demodulation circuit 322 may be built in 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.

[0056] [Functions of Smart ECU11] 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.

[0057] The vehicle information acquisition unit F1 acquires various information (hereinafter, vehicle information) indicating the state of the vehicle Hv from sensors, ECUs (e.g., body ECU 17), switches, etc. mounted on the vehicle Hv. Examples of the 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.

[0058] 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 an electric signal from the door button 14 or the start button 15 corresponds to detecting the user's operation on these buttons. That is, 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 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.

[0059] 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. In this embodiment, as a more preferred aspect, the wireless communication between the smart ECU 11 and the smartphone 2 is configured to be encrypted. As an encryption method, various methods can be used, such as a method specified by Bluetooth.

[0060] In the present embodiment, the smart ECU 11 and the smartphone 2 are configured to encrypt data communication for authentication and the like in order to improve security, but the present invention is not limited to this. As another aspect, the smart ECU 11 and the smartphone 2 may be configured to perform data communication without encryption.

[0061] 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 communicator 13, the terminal ID of the smartphone 2 to which the BLE communicator 13 is communicatively connected. With this configuration, even if the vehicle Hv is shared by multiple users, the smart ECU 11 can identify the user present in the vicinity of the vehicle Hv based on the terminal ID of the smartphone 2 to which the BLE communicator 13 is communicatively connected.

[0062] 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.

[0063] The authentication processing unit F3 cooperates with the BLE communication device 13 to perform a process of confirming that the communication partner is the smartphone 2 of the user (in other words, authentication). The communication for authentication is encrypted and performed via the BLE communication device 13. That is, 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 authentication processing unit F3 may be configured to perform encrypted communication for the authentication process, triggered by a predetermined user operation on the vehicle Hv, such as when the start button 15 is pressed by the user.

[0064] Incidentally, in the Bluetooth standard, the establishment of a communication connection between the BLE communicator 13 and the smartphone 2 means that the communication partner of the BLE communicator 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 communicator 13 and the smartphone 2.

[0065] 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 later, the internal processing time Tb is transmitted from the smartphone 2 by 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.

[0066] 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 a round trip time Tp from each UWB communication device 12 via the communication processing unit F2. It also acquires an internal processing time Tb from the flash memory 112. The round trip time Tp is a time including a propagation time of a 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.

[0067] 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, which is 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 later.

[0068] The vehicle control unit F7 is configured to execute vehicle control in accordance with the position of the smartphone 2 (in other words, the user) and the state of the vehicle Hv in cooperation with the body ECU 17 etc., when the authentication processing unit F3 has successfully authenticated 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.

[0069] For example, when the vehicle Hv is parked, the smartphone 2 is outside the vehicle compartment, 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, when the position estimation unit F6 determines that the smartphone 2 is inside the vehicle compartment 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.

[0070] [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.

[0071] Fig. 9 shows the process of the position estimation process executed by the smart ECU 11. Of the steps shown in Fig. 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 Fig. 9 is executed for each UWB communication device 12. Fig. 10 shows the process of the position estimation process executed by the terminal side control unit 25 of the smartphone 2.

[0072] 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.

[0073] In S12, a connection establishment signal is transmitted from the UWB communication device 12 to the surroundings of the vehicle Hv. In S13, it is determined whether a response radio wave transmitted from the UWB communication unit 21 of the smartphone 2 in response to the connection establishment signal is received within a certain period of time. If the determination result in S13 is NO, the process shown in FIG. 9 is terminated.

[0074] If the determination result 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 determination result 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 determination result in S14 is NO, the process proceeds to S16. In S16, if the internal processing time Tb of the smartphone 2 has already been 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 in the smartphone 2 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.

[0075] 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, a 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.

[0076] 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 transmission of the impulse signal, 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, assuming a state in which the user is sufficiently far away (for example, 10 m or more) from the vehicle Hv.

[0077] In S21, the distance from the UWB communication device 12 to the smartphone 2 is calculated by multiplying the propagation time Ta calculated in S20 by the speed of light.

[0078] S22 is executed when the 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.

[0079] 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 estimation of the position based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2 can be performed using the principle of triangulation. As a method of 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).

[0080] The position of the smartphone 2 estimated as described above (hereinafter, terminal position) is referenced by the vehicle control unit F7 and the like. For example, it is determined whether 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 traveling based on the determination result.

[0081] 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 the 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 included in the in-vehicle system 1 through BLE communication.

[0082] 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, the process proceeds to S38. If the determination result in S31 is NO, the process proceeds 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, the process proceeds to S33.

[0083] 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. The internal processing time Tb may already be stored in the flash memory 112 when the internal processing time Tb is measured and stored in the flash memory 112 at the time of shipment. There may also be cases where the internal processing time Tb has already been determined in order to provide it to the in-vehicle system 1 equipped in another vehicle Hv.

[0084] 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.

[0085] If the determination result in S33 is YES, the process proceeds to S37. The process 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.

[0086] [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).

[0087] When calculating the propagation time Ta, the internal processing time Tb stored in the flash memory 112 is used. Therefore, it is possible to calculate the propagation time Ta with high accuracy. As a result, it is possible to estimate the distance with high accuracy, and based on the accurate distance, it is possible to estimate the position of the smartphone 2 with high accuracy.

[0088] <Second embodiment> Next, a second embodiment will be described. In the following description of the second embodiment, elements having the same reference numbers as those used up to that point are the same as those in the previous embodiment unless otherwise specified. In addition, when only a part of the configuration is described, the previously described embodiment can be applied to the other parts of the configuration.

[0089] 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.

[0090] Then, the terminal-specific information acquisition unit F4 may acquire from the server 3 the internal processing time Tb of the smartphone 2 with which a connection has been established.

[0091] 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 follows. 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.

[0092] <Third embodiment> Furthermore, when focusing on the model dependency of the internal processing time Tb, it is not necessary to obtain the internal processing time Tb individually from the smartphone 2. Therefore, for a plurality of models of smartphones 2, the internal processing times Tb for each model may be obtained collectively 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.

[0093] <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.

[0094] Fig. 11 shows the configuration of a smartphone 102 in a digital key system of the fourth embodiment. The smartphone 102 differs from the smartphone 2 in the previous embodiments in that it includes an NFC communication unit 124. Fig. 12 shows the configuration of an in-vehicle system 101 in a digital key system of the fourth embodiment. The in-vehicle system 101 differs from the in-vehicle system 1 in the previous embodiments in that it includes an NFC communication unit 115.

[0095] 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 maximum. However, when performing NFC communication, a user usually often touches the smartphone 102 to the surface of a communication device of the communication partner. Therefore, the communication distance during actual communication is shorter than 10 cm and is almost constant.

[0096] Therefore, the propagation time Ta when the NFC communication unit 115 communicates with the NFC communication unit 124 can be calculated without performing communication. The flash memory 112 stores this propagation time Ta.

[0097] The NFC communication unit 115 can be installed in various positions. In this embodiment, it is assumed that a plurality of NFC communication units 115 are provided, one of which is accommodated in the door handle. The NFC communication unit 124 provided in the smartphone 102 transmits digital key information to the NFC communication unit 115 accommodated in the door handle. At this time, the authentication processing unit F3 executes authentication processing.

[0098] Also, 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 authentication of the digital key information by NFC communication is established, the in-vehicle system 101 can start operation similar to when the start button 15 is pressed.

[0099] Fig. 13 shows the process executed by the terminal specific information acquisition unit F4 in the fourth embodiment. The process shown in Fig. 13 is executed periodically, for example, with an execution period similar to that of the position estimation process.

[0100] 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, it can be estimated that the position of the smartphone 102 is a known position in contact with the NFC communication unit 115. Since the attachment 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.

[0101] In S42, it is determined whether or not the internal processing time Tb of the smartphone 102 is stored in the flash memory 112. If the determination result in S42 is NO, that is, 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.

[0102] If the determination result in S42 is YES, that is, if 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 in which the positioning signal is a baseband signal is transmitted from one UWB communication device 12 that has been set in advance. In S44, a response radio wave in which the positioning signal is a baseband signal transmitted from the smartphone 102 in response to the positioning signal is received. 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.

[0103] In S46, Tp-2Ta is calculated from the round trip time Tp acquired in S45 and the propagation time Ta stored in flash memory 112 in association with NFC communication unit 115, and an internal processing time Tb is calculated. In S47, the internal processing time Tb calculated in S46 is stored in flash memory 112.

[0104] 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 in the process shown in Fig. 9, and executes S17 and thereafter. At that time, in S20, if the internal processing time Tb is stored in the flash memory 112, the propagation time Ta is calculated using the internal processing time Tb. If the internal processing time Tb is not stored, the propagation time Ta is calculated using an initial value.

[0105] Since the smart ECU 11 executes such 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.

[0106] [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, while 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 thereafter accurately estimate the position of the smartphone 102 by a position estimation process when the smartphone 102 is not in a known position.

[0107] <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.

[0108] However, an on-board camera may be provided and the position of the smartphone 102 may be determined by analyzing images from the on-board camera. In this way, it is not necessary to install a communication unit at a location that is to be determined as a known position, and therefore there are fewer restrictions on the known position compared to the case where the NFC communication unit 115 is installed.

[0109] 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, the center of the steering wheel, etc. The known position is preferably a position where there is good visibility of radio waves between the UWB communication device 12 and the vehicle.

[0110] The owner of the smartphone 102 can also be instructed through 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 can also be given even if the known position is only the position in contact with the NFC communication unit 124.

[0111] Then, after 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, the smartphone 102 outputs that fact from the notification unit 26.

[0112] Note that the smartphone 102 may be notified of the determination result as to whether or not the smartphone 102 is in a known position, regardless of whether or not an instruction is given to position the smartphone 102 in a known position.

[0113] 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.

[0114] In this case, it is possible to determine that the smartphone 102 is in a known position based on the fact that the wireless charging device is charging. Note that the wireless charging device can determine that charging is in progress based on, for example, power supply efficiency.

[0115] Seventh embodiment In the embodiments described above, 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.

[0116] To accurately estimate the distance 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 above embodiments, the terminal specific information acquisition unit F4 acquires, as the terminal specific information, the transmission power when the UWB communication unit 21 of the smartphone 2 transmits the response radio waves.

[0117] 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 distance information. Since the power attenuation rate is proportional to the distance, the distance is estimated from the power attenuation rate. After estimating the distance, the position of the smartphone 2 can be estimated in the same manner as in the first embodiment.

[0118] The modified examples described in the second embodiment can also be applied to the case where the position of the smartphone 2 is estimated based on the power attenuation rate. That is, the transmission power may be stored in the server 3. The terminal specific information acquisition unit F4 may 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 to the case where the position of the smartphone 2 is estimated based on the power attenuation rate.

[0119] 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.

[0120] In the eighth embodiment, similarly to the fourth embodiment, the smart ECU 11 estimates the internal processing time Tb of the smartphone 2. In the fourth embodiment, the smartphone 102 needs to be in a known position. In contrast, in the eighth embodiment, the smartphone 2 does not need to be in a known position.

[0121] First, an outline 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 reflects radio waves. Even if the housing is not made of metal, there is metal inside the smartphone 2. Therefore, the smartphone 2 reflects 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.

[0122] Fig. 14 shows a process executed by the terminal specific information acquisition unit F4 in the eighth embodiment. The process shown in Fig. 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 the BLE communication or UWB communication.

[0123] In S51, it is determined whether the smartphone 2 is in the vicinity of the vehicle. In other words, it is determined whether 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. In addition, a camera may be provided, and the position of the smartphone 2 may be estimated by analyzing images captured by the camera.

[0124] 14 is terminated. On the other hand, if the determination result of 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 subsequent steps. The reason that S52 and subsequent steps 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 wave is caused by reflection by the smartphone 2.

[0125] 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. The vehicle radio wave is reflected by various radio wave reflecting objects such as metal. In addition, there may be various radio wave reflecting objects around 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.

[0126] However, S53 determines 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, it can be assumed that the reflected radio wave received first is the result of reflection 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. S54 determines the reception time at which the reflected radio wave was received (hereinafter, the reflected radio wave reception time). The reflected radio wave reception time is an example of reflected radio wave information.

[0127] 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 when 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.

[0128] In S57, it is determined whether the reflected radio wave is a reflected radio wave from the 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 reflected radio wave from the smartphone 2. In addition, 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 the smartphone 2. If it is determined that the reflected radio wave is not from the smartphone 2, that is, if the determination result in S57 is NO, the process shown in FIG. 14 is terminated.

[0129] 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. FIG. 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 FIG. 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 the flash memory 112 as the internal processing time Tb.

[0130] After storing the internal processing time Tb in this way, in the position estimation process, the smart ECU 11 omits S11 to S16 of the process shown in Fig. 9 and executes S17 and thereafter. At that time, in S20, if the internal processing time Tb is stored in the flash memory 112, the propagation time Ta is calculated using the internal processing time Tb. If the internal processing time Tb is not stored, the propagation time Ta is calculated using an initial value. During the connection establishment, the terminal side control unit 25 of the smartphone 2 executes only S38 and S39 in the process shown in Fig. 10.

[0131] [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.

[0132] In the eighth embodiment, when 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 of a reflected radio wave that is not reflected by the smartphone 2 from being determined.

[0133] <Ninth embodiment> The 9th embodiment is a modification of the 8th embodiment. In the 8th 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 9th embodiment, the distance between the smartphone 2 and the receiver included in the in-vehicle system 1 is estimated based on the reception power when the in-vehicle system 1 receives the radio wave transmitted from the smartphone 2.

[0134] In the ninth embodiment, the terminal specific information acquisition unit F4 determines the reception 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 a transmission radio wave, and the reception power of the reflected radio wave. Note that the transmission power of the vehicle radio wave is assumed to be acquired in advance by measurement or the like.

[0135] The received power of the reflected radio wave decreases as the round-trip distance between the UWB communication device 12 and the smartphone 2 increases. It is known that the power of radio waves 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.

[0136] Furthermore, the terminal-specific information acquisition unit F4 acquires the reception 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 reception 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 this transmission power of the response radio wave as terminal-specific information.

[0137] The distance estimation unit F5 calculates the power attenuation rate of the received power received by the UWB communication device 12 in 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.

[0138] 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. <Variation 1> In the embodiment, the smartphones 2 and 102 are exemplified as the mobile terminal. However, as the mobile terminal, devices other than the smartphones 2 and 102, such as a tablet terminal or a wearable terminal, may also be used.

[0139] <Variation 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.

[0140] <Modification 3> In the embodiment, three or more distances from the UWB communication device 12 to the smartphones 2, 102 are estimated, and then the positions of the smartphones 2, 102 are estimated based on the distances. However, it may be possible to determine whether or not to operate the in-vehicle device based on the distance of the smartphones 2, 102 without estimating the positions. [Explanation of symbols]

[0141] 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 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

1. 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 received 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 received 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. 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.

3. 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 received 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 received 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. 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.

5. 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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