Position determination device, position determination method, and vehicle electronic key system

Abstract

To provide a position determination device, a position determination method, and an electronic key system for vehicles with which it is possible to reduce the possibility of a position of a portable instrument for vehicles being erroneously determined.SOLUTION: A smart ECU transmits from a plurality of LF transmitters an LF signal that includes a transmitter number that indicates a transmission source, and measures a distance to a smart key using a BLE communication instrument. The smart key transmits a BLE signal that indicates LF reception intensity per transmission source toward the smart ECU at prescribed timing. The smart ECU holds a map that indicates a combination of the distance and the LF reception intensity that is observable when the smart key exists in a prescribed area such as an area near a vehicle door or in a vehicle interior. The smart ECU verifies an actual observed value pertaining to the distance and the LF reception intensity against contents registered in the map, so as to determine whether or not the smart key exists in a target area.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a technique for determining the position of a vehicle portable device relative to a vehicle based on the reception status of a wireless signal transmitted from the vehicle portable device carried by a user. [Background technology]

[0002] Patent Document 1 discloses an electronic key system for a vehicle that determines the location of a vehicle portable device relative to the vehicle by communicating between an in-vehicle device and a vehicle portable device using radio waves in the low frequency (LF) band. Specifically, the system discloses a configuration in which the in-vehicle device transmits a response request signal using radio waves in the LF band from a transmitter located in the driver's door, and determines that the vehicle portable device is in a locking / unlocking area based on receiving a response signal to the response request signal. The locking / unlocking area is an area outside the vehicle cabin within a predetermined distance from the door where the in-vehicle system locks / unlocks the door. In this disclosure, the vehicle portable device refers to a dedicated device that functions as a vehicle key, such as a key fob, smart key, or key card.

[0003] In order to prevent theft, a system requirement for a vehicle electronic key system is that automatic door unlocking via wireless communication with the vehicle portable device will not be performed if the user is more than a certain distance (for example, 2 meters) from the vehicle. For security reasons, the aforementioned locking and unlocking area is often set to an area within 2 meters of the vehicle, such as within 1 meter of the door.

[0004] Many electronic key systems and location determination systems for vehicles use LF radio waves to transmit signals from the vehicle to the portable device because the range of the radio signal is easily limited to the vicinity of the vehicle. The antenna for transmitting LF radio waves in the vehicle has its transmission power and other settings adjusted so that the radio signal reaches only the relevant locking / unlocking area. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5438048 Summary of the Invention [Problem to be solved by the invention]

[0006] A relay attack is a concern with location determination methods using LF signals. A relay attack is a method of illegally unlocking a vehicle by relaying an LF signal to a vehicle portable device located away from the vehicle using a repeater, causing the vehicle portable device to return a response signal. To address this issue, a technology is being considered in which a predetermined communication device performs distance measurement communication with the vehicle portable device to measure the distance to the vehicle portable device, and if the measured distance is equal to or less than a predetermined area judgment value, the vehicle portable device is determined to be within a locking / unlocking area. The area judgment value is a threshold parameter for the measured distance value used to determine whether the portable device is within a predetermined area, such as a locking / unlocking area. The measured distance value is a parameter that indicates the measurement result of the distance from the vehicle portable device.

[0007] However, in this studied configuration, erroneous determinations may occur depending on the installation location of the communication device that performs the distance measurement. For example, if the distance measurement communication device is installed in a location that is offset from the center of the locking / unlocking area, such as the left C-pillar of the vehicle, the threshold value for the distance measurement value (i.e., the area determination value) must be set to a large value so that it includes the locking / unlocking area. However, if the area determination value is increased, areas outside the locking / unlocking area where the distance measurement value is less than the area determination value may occur / increase. As a result, an event may occur in which a device is erroneously determined to be within the locking / unlocking area even when it is outside the locking / unlocking area.

[0008] The present disclosure has been made based on the above considerations, and one of its purposes is to provide a position determination device, a position determination method, and a vehicle electronic key system that can reduce the risk of erroneously determining the position of a vehicle portable device. [Means for solving the problem]

[0009] Disclosed herein 1st The position determination device is configured to be able to transmit signals in a first frequency band. multiple and at least one second communication device (7) configured to be capable of communicating with a vehicle portable device carried by a vehicle user using radio waves in a second frequency band different from the first frequency band, and the position determination device is configured to use at least one processor, The second communication device is configured to be able to communicate with a portable terminal (3), which is a general-purpose information processing terminal different from the vehicle portable device, using radio waves in the second frequency band; The processor acquires first data indicating a reception state at the vehicle portable device for a signal transmitted by the first communication device, and acquires second data indicating a distance from the second communication device to the vehicle portable device, the distance being determined by causing the second communication device to communicate with the vehicle portable device; The acquired first data and second data are compared with determination data, which is a data set that associates the first data and the second data for each first communication device that can be observed when the vehicle portable device is present within a predetermined target area and is stored in a determination data storage unit (M2), thereby determining whether the vehicle portable device is present within the target area. To do, acquiring a signal indicating a device type from a communication partner in cooperation with a second communication device; determining whether or not the device type of the communication partner corresponds to a vehicle portable device based on the signal acquired from the communication partner; and changing an algorithm for determining the location of the communication partner depending on whether or not the device type of the communication partner is a vehicle portable device; The system is configured to: A second position determination device included in the present disclosure is a position determination device using at least one processor connected to at least one first communication device (8) configured to be able to transmit signals in a first frequency band and at least one second communication device (7) configured to be able to communicate with a vehicle portable device carried by a user of the vehicle using radio waves in a second frequency band different from the first frequency band, wherein the processor is configured to perform the following: acquire first data indicating a reception status at the vehicle portable device for a signal transmitted by the first communication device; acquire second data indicating a distance from the second communication device to the vehicle portable device, which is determined by having the second communication device communicate with the vehicle portable device; and determine a position of the vehicle portable device based on the first data and the second data; The sensor is configured to acquire, as second data, a round trip time, which is the time from transmitting a response request signal to the vehicle portable device to receiving a response signal from the vehicle portable device, and a transmission / reception phase difference for each frequency obtained by transmitting and receiving continuous wave signals of multiple frequencies belonging to the second frequency band, acquire a phase difference ranging value indicating the distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency, determine that the vehicle portable device is not present in the predetermined target area if the round trip time is equal to or greater than a predetermined value, or if the phase difference ranging value is equal to or greater than a predetermined value even if the round trip time is less than the predetermined value, and perform a position determination process for the vehicle portable device using the first data, provided that the round trip time is less than the predetermined value and the phase difference ranging value is less than the predetermined value.

[0010] According to the above configuration, the position of the vehicle portable device is determined using not only the second data indicating the distance between the second communication device and the vehicle portable device, but also the first data determined depending on the status of wireless communication using radio waves in a different frequency band. This configuration provides more information for determination than a configuration in which the position of the vehicle portable device is determined using only the second data, thereby improving the accuracy of the position determination. In other words, it is possible to reduce the risk of erroneously determining the position of the vehicle portable device.

[0011] Also, the present disclosure 1st The location determination method is configured to transmit a signal in a first frequency band. multiple The first communication device (8) and a second frequency band different from the first frequency band are used. Car Dual-purpose handheld and mobile devicesa first processor connected to the vehicle portable device and used in connection with at least one second communication device (7) configured to be able to communicate with the first communication device; and a processor executing the position determination method, the first processor including the processor includes: acquiring, from the vehicle portable device, first data indicating a reception status at the vehicle portable device of a signal transmitted by the first communication device; and acquiring, by causing the second communication device to communicate with the vehicle portable device, second data indicating a distance from the second communication device to the vehicle portable device. determining whether the vehicular portable device is present within a target area by comparing the acquired first data and second data with determination data, which is a data set stored in a determination data storage unit (M2) and which associates first data and second data for each first communication device that can be observed when the vehicular portable device is present within a predetermined target area; acquiring a signal indicating a device type from a communication partner in cooperation with the second communication device; determining whether the device type of the communication partner corresponds to a vehicular portable device based on the signal acquired from the communication partner; and changing an algorithm for determining the location of the communication partner depending on whether the device type of the communication partner is a vehicular portable device. Includes. A second position determination method included in the present disclosure is a position determination method executed by at least one processor connected to and used with at least one first communication device (8) configured to be able to transmit signals in a first frequency band and at least one second communication device (7) configured to be able to communicate with a vehicle portable device carried by a user of the vehicle using radio waves in a second frequency band different from the first frequency band, and includes the steps of: acquiring, from the vehicle portable device, first data indicating a reception status at the vehicle portable device for a signal transmitted by the first communication device; acquiring second data indicating a distance from the second communication device to the vehicle portable device, the distance being determined by causing the second communication device to communicate with the vehicle portable device; determining a position of the vehicle portable device based on the first data and the second data; and transmitting a response request signal to the vehicle portable device as the second data. and acquiring a round trip time, which is the time from transmitting a signal to receiving a response signal from the vehicle portable device, and a transmission / reception phase difference for each frequency obtained by transmitting and receiving continuous wave signals of a plurality of frequencies belonging to the second frequency band, and acquiring a phase difference ranging value indicating the distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency. Determining the location of the vehicle portable device includes determining that the vehicle portable device is not present in the predetermined target area if the round trip time is equal to or greater than a predetermined value, or if the phase difference ranging value is equal to or greater than a predetermined value even when the round trip time is less than the predetermined value, and performing a location determination process for the vehicle portable device using the first data, under the condition that the round trip time is less than the predetermined value and the phase difference ranging value is less than the predetermined value.

[0012] The vehicle electronic key system of the present disclosure includes a position determination device (4) having at least one processor (41) connected to at least one first communication device (8) configured to be able to transmit signals in a first frequency band and at least one second communication device (7) configured to be able to perform wireless communication using radio waves in a second frequency band different from the first frequency band; a vehicle portable device (2) that is a dedicated device for a user to operate the vehicle and configured to receive signals transmitted from the first communication device and to be able to perform wireless communication using the second frequency band; and a portable terminal (3) that is a general-purpose information processing terminal configured to be able to perform wireless communication using the second frequency band, wherein the vehicle portable device is activated based on receiving the signal in the first frequency band, and initiates a wireless communication connection with the position determination device using radio waves in the second frequency band, transmits data indicating the reception strength of the signal in the first frequency band via the wireless communication using the second frequency band, and transmits a code indicating that the device type is the vehicle portable device based on the establishment of the communication connection with the position determination device; and transmitting and receiving a signal for ranging with the second communication device when a communication connection with the position determination device is established, and the portable terminal performs a process for the communication connection with the position determination device using radio waves in the second frequency band, and when a communication connection with the position determination device is established, transmitting and receiving a signal for ranging with the second communication device, and, based on the establishment of the communication connection with the position determination device, transmitting a code indicating that the device type is not a vehicle portable device, and the position determination device acquires second data indicating the distance from the second communication device to the communication partner, which is determined by having the second communication device perform a predetermined distance measurement communication, acquires a signal indicating the device type from the communication partner using the second communication device, and, based on the signal acquired from the communication partner, determines whether the device type of the communication partner is a vehicle portable device, and, if the device type of the communication partner is a vehicle portable device, acquires first data from the vehicle portable device as the communication partner indicating a reception status at the vehicle portable device for the signal transmitted by the first communication device, and, if the device type of the communication partner is a vehicle portable device,and determining the location of the vehicle portable device.

[0013] The above-described location determination method / vehicle electronic key system can achieve the same effects as the location determination device. Note that the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of the present disclosure. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing a configuration of an in-vehicle system. [Figure 2] FIG. 2 is a block diagram showing the configuration of a smart key. [Figure 3] FIG. 2 is a block diagram showing the configuration of a mobile terminal. [Figure 4] FIG. 10 is a diagram illustrating an example of the mounting positions of an LF transmitter and a BLE communication device. [Figure 5] FIG. 1 is a block diagram showing the configuration of a BLE communication device. [Figure 6] FIG. 2 is a functional block diagram of a smart ECU. [Figure 7] FIG. 10 is a diagram for explaining an example of a method for constructing / generating an intensity map. [Figure 8] FIG. 10 is a conceptual diagram showing an example of the configuration of an intensity map. [Figure 9] 10 is a flowchart illustrating an example of a map generation process. [Figure 10] 4 is a flowchart illustrating an example of a vehicle control process. [Figure 11] 10 is a flowchart illustrating an example of a position determination process when the communication partner is a smart key. [Figure 12] 10 is a flowchart illustrating an example of a position determination process when the communication partner is a mobile terminal. [Figure 13] 10A and 10B are diagrams for explaining the effect of determining the device location using an intensity map when the communication partner is a smart key. [Figure 14]10A and 10B are diagrams illustrating modified examples of the mounting positions of the LF transmitter and the BLE communication device. [Figure 15] 10 is a flowchart conceptually illustrating an example of the operation of a processor in accordance with a communication partner. [Figure 16] 10A and 10B are diagrams illustrating modified examples of the mounting positions of the LF transmitter and the BLE communication device. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a schematic configuration of a vehicle electronic key system. As shown in FIG. 1, the vehicle electronic key system includes an in-vehicle system 1 and a smart key 2. The vehicle electronic key system also includes one or more mobile terminals 3 as optional elements. The in-vehicle system 1 is a system installed in the vehicle Hv. The smart key 2 is a dedicated device as an electronic key for the vehicle Hv. The mobile terminal 3 is a general-purpose information processing terminal carried by the user of the vehicle Hv.

[0016] <Preface> In the following description, the vehicle Hv is, as an example, a vehicle owned by an individual. Therefore, the user of the vehicle Hv refers to the owner, his / her family, etc. Of course, the vehicle Hv may be a company car owned by a company organization or an official car owned by a public institution. If the vehicle Hv is a company car or an official car, the user may be a person belonging to the organization that manages the vehicle Hv. Furthermore, the vehicle Hv may be a vehicle provided for a rental service (a so-called rental car) or a vehicle provided for a car sharing service (a so-called shared car). The vehicle Hv may also be a vehicle provided for a passenger transportation service such as a robot taxi. If the vehicle Hv is a vehicle provided for the above services (hereinafter referred to as a service vehicle), the user may be a person who has signed a service contract for the service and has the authority to temporarily use the vehicle Hv based on a service reservation, etc.

[0017] An example of a hybrid vehicle is an engine vehicle. An engine vehicle refers to a vehicle that has only an engine as a drive source. Engine vehicles also include diesel vehicles. In another aspect, a hybrid vehicle may be an electric vehicle. The concept of an electric vehicle includes not only electric vehicles but also hybrid vehicles and fuel cell vehicles. An electric vehicle is a vehicle that has only a motor as a drive source. A hybrid vehicle is a vehicle that has an engine and a motor as a power source. Hybrid vehicles also include plug-in hybrid vehicles. Furthermore, a hybrid vehicle may be any vehicle that has a driver's door, and can be installed in a variety of vehicles that can travel on roads, such as trailers, tank trucks, and convertibles.

[0018] The vehicle Hv is a vehicle with the driver's seat on the right side. In another embodiment, the vehicle Hv may be a vehicle with the driver's seat on the left side. In the following description, the front-to-back, left-to-right, and up-to-down directions are defined based on the vehicle Hv unless there is a note regarding the reference direction (i.e., basically). The various flowcharts shown in this disclosure are all examples, and the number of steps constituting the flowcharts and the order in which the processes are executed can be changed as appropriate. In addition, the following description can be changed as appropriate to conform to the laws, regulations, and customs of the area in which the vehicle Hv is used.

[0019] <Overview> The in-vehicle system 1, the smart key 2, and the mobile terminal 3 are each configured to be capable of short-range communication. Here, short-range communication refers to communication conforming to a predetermined short-range wireless communication standard with a practical communication distance of, for example, 5 to 30 meters, and up to approximately 100 meters. Examples of short-range communication standards include Bluetooth (registered trademark) and Wi-Fi (registered trademark). The Bluetooth standard may be Bluetooth Classic or Bluetooth Low Energy (BLE). Various Wi-Fi standards, such as IEEE802.11n, IEEE802.11ac, and IEEE802.11ax, may also be adopted. IEEE (registered trademark) stands for Institute of Electrical and Electronics Engineers, and refers to the Institute of Electrical and Electronics Engineers. Alternatively, a communication method between the in-vehicle system 1 and the mobile terminal 3, in other words, a short-range communication method, may be UWB-IR (Ultra Wide Band - Impulse Radio), which uses a frequency band of 3 GHz or higher. The short-range communication is performed using high-frequency radio waves. In this disclosure, high-frequency radio waves refer to radio waves of 900 MHz or higher, such as 2.4 GHz. High-frequency radio waves are not limited to radio waves of 1 GHz or higher, but also include radio waves in the sub-gigahertz band, such as 920 GHz.

[0020] The following describes the operation of each part of the in-vehicle system 1, smart key 2, and mobile terminal 3, assuming that they each perform wireless communication conforming to the BLE standard (hereinafter referred to as BLE communication) as short-range communication. In this disclosure, wireless signals transmitted and received via BLE communication are also referred to as BLE signals. BLE signals transmitted from the smart key 2 or mobile terminal 3 to the in-vehicle system 1 include a device ID as information indicating the sender.

[0021] In the following, a case will be described in which the in-vehicle system 1 is set to act as a master in communication with the mobile terminal 3, and the mobile terminal 3 is set to act as a slave. In another aspect, the mobile terminal 3 may be set to operate as a master in communication with the in-vehicle system 1.

[0022] Additionally, the in-vehicle system 1 and smart key 2 are configured to be able to wirelessly communicate using radio waves in the LF (Low Frequency) band, such as 125 kHz or 134 kHz. That is, the in-vehicle system 1 transmits an LF signal, which is a signal with a specific frequency in the LF band, and the smart key 2 is configured to be able to receive the LF signal. Here, the LF band refers to a frequency band below 300 kHz, including frequencies between 20 kHz and 30 kHz. The smart key 2 returns response data corresponding to the received LF signal to the in-vehicle system 1 via BLE communication.

[0023] The smart key 2 and the mobile terminal 3 are devices that store key information for using the vehicle Hv and function as an electronic key for the vehicle Hv using the key information. The key information here refers to data used in the authentication process described below. The key information is data used to verify that the person attempting to access the vehicle Hv is the user, i.e., to verify the legitimacy of the person attempting to access the vehicle Hv. The key information may also be called an authentication key, encryption key, or key code. For example, the key information may be a character string (value) encrypted by inputting a password set by the user into a predetermined hash function. The key information may also be generated based on a device ID. In this disclosure, the smart key 2 and the mobile terminal 3 are collectively referred to as a key device Kd. Below, the term "key device Kd" can be replaced with the term "smart key 2" or "mobile terminal 3."

[0024] The key information may differ for each key device Kd. In the in-vehicle system 1, the key information for each key device Kd is stored and registered in association with a device ID. Multiple key devices Kd may be distinguished by a key ID assigned by the vehicle Hv in the order of registration, instead of the device ID. The device ID is expressed in a length of, for example, about 48 bits / 128 bits, while the key ID may be expressed in a number of bytes, such as 1 byte.

[0025] <About Smart Key 2> The smart key 2 is a dedicated device for the user to operate the vehicle hybrid. The smart key 2 is a device provided to the owner along with the vehicle hybrid when the vehicle hybrid is purchased. The smart key 2 is basically kept by the owner. The smart key 2 can be considered one of the accessories to the vehicle hybrid. The smart key 2 can have a variety of shapes, such as a flat rectangular parallelepiped shape, a flat ellipsoid shape (so-called fob type), or a card shape. The smart key 2 can be called a vehicle portable device, key fob, key card, access key, etc.

[0026] As shown in FIG. 2, the smart key 2 includes a key control unit 20, an operation unit 21, an LF receiving unit 22, a BLE communication unit 23, and an internal battery 24.

[0027] The operation unit 21 is configured to accept user operations on the smart key 2. A push switch or the like can be used as the operation unit 21. The operation unit 21 may include multiple switches. For example, the operation unit 21 may include a lock switch for locking the doors of the vehicle Hv and an unlock switch for unlocking the doors of the vehicle Hv. The smart key 2 provides a so-called remote keyless entry system that controls the locking / unlocking of the vehicle doors by wirelessly transmitting a remote control signal to the smart ECU 4 in accordance with the switch operated by the user.

[0028] The LF receiver 22 is configured to receive an LF signal. The LF receiver 22 is implemented using an antenna for receiving the LF signal and a circuit for demodulating the received signal (a so-called demodulation circuit). The LF receiver 22 extracts data contained in the received signal by performing predetermined processes, such as analog-to-digital conversion, demodulation, and decoding, on the signal received by the antenna. The extracted data is then provided to the key control unit 20. In addition to the received data, the LF receiver 22 outputs data indicating the reception strength of the LF signal transmitted from the in-vehicle system 1 to the key control unit 20. The signal indicating the reception strength or the measurement value thereof may also be referred to as RSSI (Received Signal Strength Indicator / Indication). In the present disclosure, the reception strength of the LF signal detected by the smart key 2 is also referred to as LF strength or LF_RSSI.

[0029] The BLE communication unit 23 is a communication module for BLE. The BLE communication unit 23 operates under the control of the key control unit 20. For example, the operation state of the BLE communication unit 23 is switched by the key control unit 20. The BLE communication unit 23 has an active state in which it can send and receive advertising signals and the like, and an inactive state in which it cannot send and receive BLE signals. The inactive state can be, for example, a state in which no power is being applied. The built-in battery 24 is a power source that supplies power for operating the smart key 2. The built-in battery 24 is, for example, a primary battery such as a lithium battery.

[0030] The key control unit 20 is configured as a microcomputer including a CPU 201 and a memory 202. The key control unit 20 may be realized using an integrated circuit (IC) or a field-programmable gate array (FPGA). The memory 202 stores key-related information. The key-related information may include, for example, key information and the ID of the vehicle Hv linked to the smart key 2 (i.e., vehicle ID).

[0031] The key control unit 20 is activated when the LF receiving unit 22 receives a wake signal having an intensity equal to or greater than a predetermined threshold, and transitions the entire smart key 2 from sleep mode to active mode. The active mode is an operating mode in which BLE communication is possible, and corresponds to, for example, an operating mode in which the BLE communication unit 23 is set to an active state. The sleep mode is an operating mode in which power consumption is reduced by limiting the functions that can be executed compared to the active mode. The sleep mode corresponds to an operating mode in which the BLE communication unit 23 is set to an inactive state.

[0032] In addition to receiving a wake signal, the key control unit 20 can also transition from the sleep mode to the active mode when the operation unit 21 is operated. That is, the key control unit 20 activates the BLE communication unit 23 in response to reception of a wake signal or a user operation on the operation unit 21. In the active mode, the key control unit 20 transitions the smart key 2 to the sleep mode when a state in which communication is not connected to the in-vehicle system 1 continues for a certain period of time, or when a state in which the operation unit 21 has not been operated continues for a certain period of time.

[0033] In the active mode, the key control unit 20 acquires information indicating the communication connection status with the in-vehicle system 1 and received data from the in-vehicle system 1 from the BLE communication unit 23. When the BLE communication unit 23 receives a challenge code, the key control unit 20 generates a response code using key information stored in the memory 202 and causes the BLE communication unit 23 to transmit the response code. When the operation unit 21 is operated, the key control unit 20 also causes the BLE communication unit 23 to transmit a control signal according to the operation content.

[0034] When the LF receiver 22 receives a wake signal, the key control unit 20 associates the LF_RSSI with information indicating the sender (e.g., a transmitter number) and holds the LF_RSSI for a certain period of time. Furthermore, the key control unit 20 causes the BLE communication unit 23 to transmit an LF strength report to the in-vehicle system 1 based on a request from the in-vehicle system 1 or spontaneously (periodically). The LF strength report is a BLE signal including data indicating the LF_RSSI for each sender. The LF_RSSI for each sender corresponds to the first data.

[0035] It is anticipated that even in the in-vehicle system 1 configured to allow the mobile terminal 3 to be used as an electronic key as in the present disclosure, the smart key 2 will continue to be sold / distributed as an accessory to the vehicle as proof of ownership or as a physical master key. It is also anticipated that some users will continue to use the smart key 2 as a vehicle key rather than the mobile terminal 3 due to their preferences. In other words, the in-vehicle system 1 may be configured to be capable of communicating with both the smart key 2 and the mobile terminal 3.

[0036] <About mobile device 3> The mobile terminal 3 is a portable, general-purpose information processing terminal equipped with a BLE communication function. Various communication terminals, such as a smartphone or a wearable device, can be used as the mobile terminal 3. A wearable device is a device worn on the user's body and can take various forms, such as a wristband, a watch, a ring, glasses, or earphones.

[0037] As shown in FIG. 3 , the mobile terminal 3 includes a BLE communication unit 31 and a device control unit 32. The BLE communication unit 31 is a communication module for performing BLE communication. The device control unit 32 is configured to execute various arithmetic processing. The device control unit 32 is configured as a computer including, for example, a processor 33, a RAM (Random Access Memory) 34, a storage 35, and the like. A digital key app, which is an application for causing the mobile terminal 3 to function as an electronic key for the vehicle HV, is installed in the storage 35. Key information is also stored in the storage 35. Like the key control unit 20, the device control unit 32 also performs processing related to communication connection and authentication with the in-vehicle system 1. That is, the device control unit 32 periodically transmits advertising signals, returns response codes, and the like in cooperation with the BLE communication unit 31.

[0038] <Configuration of In-Vehicle System 1> This section describes the configuration and operation of the in-vehicle system 1. As shown in Fig. 1, the in-vehicle system 1 includes a smart ECU 4, door buttons 5, a start button 6, a BLE communication device 7, and an LF transmitter 8. The in-vehicle system 1 also includes a power supply ECU 11, a body ECU 12, a display 13, and an input device 14. The ECU in the component names is an abbreviation for Electronic Control Unit, and refers to an electronic control device.

[0039] The smart ECU 4 is connected to the door button 5, the start button 6, and the BLE communication device 7 via dedicated signal lines. The smart ECU 4 is also connected to the power supply ECU 11, the body ECU 12, and the like so that they can communicate with each other via an in-vehicle network Nw. The in-vehicle network Nw is a communication network built inside the vehicle Hv. A variety of standards can be adopted for the in-vehicle network Nw. The connection configuration between devices shown in FIG. 1 is an example, and the specific connection configuration between devices can be changed as appropriate.

[0040] The smart ECU 4 is an ECU that determines the device position relative to the vehicle Hv in cooperation with the BLE communication device 7 and the like, and performs vehicle control according to the device position determination result. In this disclosure, the device position means the position of the key device Kd. Since the key device Kd is carried by the user, determining the device position corresponds to determining the user's position. The smart ECU 4 corresponds to a position determination device. The smart ECU 4 is located in the instrument panel. The smart ECU 4 may be attached to the interior side of the right or left C-pillar. The C-pillar refers to the third pillar from the front among the pillars equipped on the vehicle Hv.

[0041] The smart ECU 4 is implemented using a computer, and includes a processor 41, a RAM 42, a storage 43, an I / O 44, and a bus line connecting these components.

[0042] The processor 41 is hardware (in other words, an arithmetic core) for arithmetic processing coupled to a RAM (Random Access Memory) 42. The processor 41 is, for example, a CPU (Central Processing Unit). By accessing the RAM 42, the processor 41 executes various processes to realize the functions of each functional unit described below. The RAM 42 is a volatile storage medium. The storage 43 includes a non-volatile storage medium such as a flash memory. The storage 43 stores a control program executed by the processor 41. The execution of the control program by the processor 41 corresponds to the execution of a position determination method corresponding to the control program. The I / O 44 is a circuit module for communicating with other devices.

[0043] The storage 43 registers a device ID for each key device Kd. The storage 43 also stores communication device setting data indicating the installation position of each BLE communication device 7 in the vehicle Hv. The installation position of each BLE communication device 7 can be expressed as a point on a vehicle coordinate system, which is a two-dimensional coordinate system centered on an arbitrary position on the vehicle Hv and parallel to both the width direction and the longitudinal direction of the vehicle Hv. The x-axis forming the vehicle coordinate system can be set parallel to the vehicle width direction, and the y-axis can be set parallel to the longitudinal direction of the vehicle. The center of the coordinate system can be any location, such as the center of the vehicle body or the installation position of the smart ECU 4. Of course, the vehicle coordinate system may also be a three-dimensional coordinate system including a z-axis parallel to the height direction. Details of the smart ECU 4 will be described later.

[0044] The door button 5 is a switch that allows the user to unlock and lock the doors of the vehicle Hv. The door button 5 is provided on an outer door handle provided on each door. The outer door handle refers to a gripping member provided on the outer surface of the door for opening and closing the door. When pressed by the user, the door button 5 outputs an electric signal indicating this to the smart ECU 4. Note that a touch sensor can also be used as a configuration for receiving at least one of the user's unlock command and lock command. The touch sensor can be provided on the outer door handle instead of or together with the door button 5.

[0045] The start button 6 is a push switch that the user uses to turn the driving power source on and off. The driving power source is the power source for the vehicle HV to run, and if the vehicle is an engine vehicle, it refers to the ignition power source. If the vehicle HV is an electric vehicle or hybrid vehicle, the driving power source refers to the system main relay. The start button 6 corresponds to a switch for starting the drive source (e.g., the engine). When the start button 6 is pressed by the user, it outputs an electrical signal indicating this to the smart ECU 4.

[0046] The BLE communication device 7 is a communication module for wirelessly communicating with the key device Kd in accordance with the BLE standard. At least one BLE communication device 7 is provided in the vehicle Hv. As an example, the in-vehicle system 1 of this embodiment includes only one BLE communication device 7, as shown in FIG. 4 . The BLE communication device 7 is provided, for example, on the interior side of the left C-pillar. The BLE communication device 7 may be provided not only in the C-pillar but also in the B-pillar, instrument panel, center console, interior ceiling, or the upper edge of the windshield. The B-pillar refers to the second pillar from the front among the pillars provided in the vehicle Hv. The B-pillar may also be called the center pillar. The BLE communication device 7 is connected to the smart ECU 4 via a dedicated communication line or an in-vehicle network Nw so as to be able to communicate with each other. In another embodiment, the BLE communication device 7 may be built into the smart ECU 4. Alternatively, the BLE communication devices 7 may be distributed in multiple locations in the vehicle Hv. The BLE communication device 7 corresponds to the second communication device.

[0047] The LF transmitter 8 is a device that transmits an LF signal based on an instruction from the smart ECU 4. The LF transmitter 8 transmits a wake signal based on, for example, an input signal from the smart ECU 4. The wake signal is an LF signal for transitioning the smart key 2 to active mode. The LF transmitter 8 includes an LF transmission circuit and an LF transmission antenna. The LF transmission circuit is a circuit that performs predetermined signal processing such as digital-to-analog conversion, frequency conversion, modulation, etc. The LF transmission circuit may be included in the smart ECU 4.

[0048] The in-vehicle system 1 of this embodiment includes LF transmitters 8a, 8b, 8c, 8p, and 8q. The LF transmitter 8a is an LF transmitter 8 provided on the outer door handle for the driver's seat. The LF transmitter 8b is an LF transmitter 8 provided on the outer door handle for the passenger's seat. The LF transmitter 8c is an LF transmitter 8 provided near the trunk door. The LF transmitters 8p and 8q are LF transmitters 8 arranged inside the vehicle cabin. The LF transmitter 8p is arranged in the center of the instrument panel in the vehicle width direction or in front of the driver's seat so that the front seats are included in the main communication area. The LF transmitter 8q is arranged, for example, near the seating surface or footwell of the rear seat. Each LF transmitter 8 is assigned a unique transmitter number. The transmitter number corresponds to information indicating the source of the LF signal. The LF transmitter 8 corresponds to the first communication device.

[0049] The power supply ECU 11 is an ECU that controls the on / off state of the running power supply installed in the vehicle Hv. For example, the power supply ECU 11 switches the running power supply from off to on based on a command signal from the smart ECU 4. If the vehicle Hv is an engine vehicle, the power supply ECU 11 starts the engine based on a command signal from the smart ECU 4.

[0050] The body ECU 12 is an ECU that controls body system actuators based on requests from the smart ECU 4 or the user. The body ECU 12 is communicably connected to various body system actuators and various body system sensors. Here, the body system actuators are, for example, door lock motors that constitute the locking mechanisms of each door. The body system sensors include courtesy switches arranged on each door. The courtesy switches are sensors that detect the opening and closing of the doors. Based on a request from, for example, the smart ECU 4, the body ECU 12 locks or unlocks each door by outputting a predetermined control signal to a door lock motor arranged on each door of the vehicle Hv.

[0051] The display 13 is, for example, a liquid crystal display or an organic EL display. The display 13 displays an image according to an input signal from the smart ECU 4. The display 13 is disposed, for example, in the central region in the vehicle width direction of the instrument panel or in the front region of the driver's seat. The display 13 corresponds to an in-vehicle display.

[0052] The input device 14 is a device for receiving a user's instruction operation for the smart ECU 4. As the input device 14, for example, a touch panel laminated on the display 13 can be adopted. The input device 14 may be a mechanical switch provided on the instrument panel or the like. The input device 14 outputs an electrical signal corresponding to the operation performed by the user on the device to the smart ECU 4 as an operation signal. The operation signal output by the input device 14 indicates the content of the user's operation. The display 13 and the input device 14 correspond to an interface for an operator in a dealership / manufacturing plant or the like to register strength map data described later in the smart ECU 4. The display 13 and the input device 14 are collectively also referred to as an in-vehicle HMI. HMI is an abbreviation for Human Machine Interface.

[0053] <Configuration of the BLE communication device> As shown in FIG. 5, the BLE communication device 7 includes an antenna 71, a transceiver unit 72, and a communication microcomputer 73. The antenna 71 is a metal body for transmitting and receiving radio waves in a frequency band used for BLE communication, that is, a 2.4 GHz band. The antenna 71 is electrically connected to the transceiver unit 72. The antenna 71 may be configured as an array antenna formed by arranging a plurality of antenna elements. The 2.4 GHz band corresponds to the second frequency band. Note that the 2.4 GHz band may refer to, for example, from 2402 MHz to 2480 MHz or up to 2495 MHz.

[0054] The transceiver 72 demodulates the signal received by the antenna 71 and provides it to the communication microcomputer 73. The transceiver 72 also modulates a signal input from the smart ECU 4 via the communication microcomputer 73, outputs the modulated signal to the antenna 71, and radiates it as a radio wave. The transceiver 72 is connected to the communication microcomputer 73 so as to be able to communicate with each other. In addition to a modulation / demodulation circuit, the transceiver 72 includes a reception strength detection unit 721 and a ranging processing unit 722. The reception strength detection unit 721 is configured to sequentially detect the strength of the signal received by the antenna 71. The reception strength detected by the reception strength detection unit 721 is output to the communication microcomputer 73 together with a device ID indicating the sender of the received signal and frequency information of the received signal. In this disclosure, the reception strength of a BLE signal is also referred to as BLE_RSSI.

[0055] The ranging processing unit 722 performs ranging communication with the communication partner, thereby generating a distance correspondence value that indirectly indicates the distance from the BLE communication device 7 to the communication partner. The distance correspondence value here is a parameter that indicates the signal flight time from when a signal transmitted from the key device Kd is received by the BLE communication device 7. The distance correspondence value is a parameter different from the reception strength. Specifically, the distance correspondence value is the round-trip time (RTT) or the two-frequency phase difference. Ranging communication can be rephrased as communication for measuring the RTT or the two-frequency phase difference. The distance correspondence value indicates the signal flight time (ToF) for one way or a round trip, and therefore can be called a ToF-related value. The distance correspondence value, such as the RTT or the two-frequency phase difference, corresponds to the distance measurement value and the second data.

[0056] The RTT is measured as the time from when a response request signal is transmitted to the communication partner until when a response signal is received from the communication partner. The ranging processing unit 722 may use, as the RTT, a value obtained by performing a predetermined correction process, such as subtracting an estimated value of a response processing time that occurs in the key device Kd or an estimated value of a delay time that may occur in the BLE communication device 7, from the time that has elapsed since the actual transmission of a signal until it is received.

[0057] The two-frequency phase difference is a parameter determined by the BLE communication device 7 and the key device Kd transmitting and receiving continuous wave (CW) signals, and is the difference between the transmission and reception phase differences observed at each of the two frequencies. The transmission and reception phase difference at a certain frequency corresponds to the phase difference between a CW signal of the target frequency transmitted to a target and a CW signal of the target frequency returned from the target.

[0058] The transmit / receive phase difference may also be simply referred to as the phase angle. The transmit / receive phase difference can be determined, for example, by having the BLE communication device 7 and the key device Kd transmit and receive CW signals to each other, detecting the phase difference between the transmitted and received signals, and then averaging the phase differences observed between the two devices. The ranging processing unit 722 may use the received phase of the CW signal transmitted from the key device Kd as the transmit / receive phase difference, assuming that the initial phases and local oscillators of the devices are synchronized. Synchronization of the initial phases and local oscillators of the devices can be achieved, for example, by transmitting a predetermined synchronization signal. The transmit / receive phase difference for each frequency, which is the basis of the two-frequency phase difference, can also be treated as a type of ranging value. The two-frequency phase difference corresponds to the amount of change in the transmit / receive phase difference due to a change in frequency.

[0059] Based on instructions from the smart ECU 4, the BLE communication device 7 performs distance measurement communication with the smart key 2 or the mobile terminal 3, generates a distance correspondence value, and reports it to the processor 41. In a more preferred aspect of this embodiment, the distance measurement processing unit 722 calculates both the RTT and the two-frequency phase difference. Furthermore, the distance measurement processing unit 722 calculates the two-frequency phase difference for each combination of frequencies used in the BLE communication. Note that the generation (calculation) of the distance correspondence value may be performed by the communication microcomputer 73 or the smart ECU 4. For example, the distance measurement processing unit 722 may identify the transmission and reception phase difference for each frequency, and the smart ECU 4 may calculate the two-frequency phase difference for each combination of frequencies based on the transmission and reception phase difference for each frequency. The division of functions between the BLE communication device 7 and the smart ECU 4 can be changed as appropriate.

[0060] The communication microcomputer 73 is a microcomputer that controls the exchange of data with the smart ECU 4. The communication microcomputer 73 is realized using a CPU, RAM, ROM (Read Only Memory), etc. The communication microcomputer 73 provides the received data input from the transmitter / receiver 72 to the smart ECU 4 sequentially or based on a request from the smart ECU 4. The communication microcomputer 73 also outputs data related to the reception status of signals from the key device Kd and distance correspondence values ​​to the smart ECU 4 based on a request from the smart ECU 4 or spontaneously.

[0061] The BLE communication device 7 may be configured to calculate the direction of arrival of the signal as information indicating the reception status of the signal from the key device Kd and output it to the smart ECU 4. The direction of arrival of the signal can be estimated using various methods, such as the MUSIC algorithm or the ESPRIT algorithm. The received signal strength, phase, and direction of arrival can be called received wave characteristics.

[0062] <About the Smart ECU4 functions> Here, the functions and operations of the smart ECU 4 will be described. The smart ECU 4 provides functions corresponding to the various functional blocks shown in Figure 6 by executing programs stored in the storage 43. That is, the smart ECU 4 includes, as functional units, a vehicle information acquisition unit F1, a communication control unit F2, a position determination unit F3, an authentication processing unit F4, and a vehicle control unit F5. The communication control unit F2 includes, as sub-functional units, an LF control unit F21 and a BLE control unit F22.

[0063] The smart ECU 4 also includes a key information storage unit M1 and an intensity map storage unit M2. The key information storage unit M1 and the intensity map storage unit M2 are realized using part of the storage area of ​​the storage 43. Either or both of the key information storage unit M1 and the intensity map storage unit M2 may be realized using a non-volatile storage medium that is physically independent from the storage 43. The key information storage unit M1 and the intensity map storage unit M2 are configured so that the processor 41 can write, read, delete, and so on data therein.

[0064] The key information storage unit M1 is a storage medium for storing information about key devices Kd used as electronic keys for the vehicle Hv. The key information storage unit M1 stores key information for each key device Kd and each user, associated with a key ID, device ID, user ID, device type data, and the like. The user ID is an identifier for identifying multiple users and is set for each user. The device type refers to either the smart key 2 or the mobile terminal 3. If the vehicle Hv is a service car, the smart ECU 4 may obtain device information for the user who has reserved use in advance from a digital key server that issues key information and store it in the key information storage unit M1. Information such as expiration date, authority, and seat position may be linked to the key information for each user / device.

[0065] The strength map storage unit M2 is a storage medium that stores a strength map that indicates the LF_RSSI for each measurement point that is set at a predetermined interval within at least the locking / unlocking area EA. The strength map will be described in detail later.

[0066] The vehicle information acquisition unit F1 acquires various vehicle information indicating the state of the vehicle Hv and user operations on the vehicle Hv from sensors, ECUs, switches, etc. mounted on the vehicle Hv. The vehicle information includes, for example, the state (on / off) of the driving power supply, the open / closed state of each door, the locked / unlocked state of each door, the pressed state of the door buttons 5 and start button 6, and the shift position. The output value of a brake sensor that detects the amount / force of depression of the brake pedal and a signal indicating the actuation state of the parking brake may also be considered vehicle information. Note that acquiring electrical signals from the door buttons 5 and start button 6 corresponds to detecting user operations on these buttons. In one aspect, the vehicle information acquisition unit F1 corresponds to a configuration that detects user operations on the vehicle Hv, such as pressing the door button 5, opening / closing the doors, pressing the start button 6, etc.

[0067] The vehicle information acquisition unit F1 acquires the current state of the vehicle Hv based on the various pieces of information described above. For example, the vehicle information acquisition unit F1 determines that the vehicle Hv is parked when the running power supply is off and all doors are locked. The conditions for determining that the vehicle Hv is parked can be designed as appropriate, and a variety of determination conditions can be applied. Note that "acquire" in this disclosure also includes generating / detecting / determining by internal calculation based on data input from other devices / sensors, etc. This is because the functional layout within the system is subject to change as appropriate.

[0068] The communication control unit F2 controls the operations of the BLE communication device 7 and the LF transmitter 8. The configuration that controls the LF transmitter 8 corresponds to the LF control unit F21, and the configuration that controls the BLE communication device 7 corresponds to the BLE control unit F22.

[0069] The communication control unit F2, which functions as the LF control unit F21, causes the multiple LF transmitters 8 to transmit wake signals in sequence at a predetermined polling interval while the vehicle Hv is parked. The wake signal includes at least a transmitter number as transmission source information. The polling interval is set to, for example, 200 milliseconds. When the communication control unit F2 detects a user's operation of an operating member provided on the vehicle Hv, such as a door button 5, a start button 6, or a brake pedal, the communication control unit F2 may cause the LF transmitter 8 corresponding to the operated member to transmit a wake signal. For example, the communication control unit F2 may cause the LF transmitter 8b to transmit a wake signal in response to pressing the door button 5 provided on the left door. In the present disclosure, transmitting a wake signal based on the detection of a user's operation of the door button 5, the start button 6, or the like is also referred to as trigger transmission. The communication control unit F2 may stop / suspend transmission of the LF signal when connected to the smart key 2 via BLE communication.

[0070] The communication control unit F2 as the BLE control unit F22 performs data communication with the key device Kd using the BLE communication device 7. For example, the communication control unit F2 generates data addressed to the connected key device Kd and outputs it to the BLE communication device 7. This causes a signal corresponding to the desired data to be transmitted as radio waves. The communication control unit F2 also receives data from the key device Kd that has been received by the BLE communication device 7. In this embodiment, as a more preferred mode, data communication between the smart ECU 4 and the key device Kd is performed in an encrypted form.

[0071] The communication control unit F2 recognizes that the user is present near the vehicle Hv based on receiving a BLE signal transmitted from the key device Kd. That is, the BLE communication device 7x detects the key device Kd present near the vehicle Hv using a passive scan method. The in-vehicle system 1 may also search for the key device Kd using an active scan method that involves transmitting a scan request. The two scan methods may be used differently depending on the situation. For example, the passive scan method may be used when waiting while parked, while the active scan method may be used when a predetermined verification event occurs, such as pressing the door button 5.

[0072] The communication control unit F2 also acquires the device ID of the connected key device Kd from the BLE communication device 7. The smart ECU 4 identifies a user present near the vehicle Hv based on the received device ID. The communication control unit F2 determines, based on the device ID, whether the device type of the communication partner corresponds to the smart key 2.

[0073] The communication control unit F2 acquires the reception status and distance correspondence value of the signal from the key device Kd from the BLE communication device 7. For example, the communication control unit F2 acquires the reception strength and transmission / reception phase difference for each frequency as data indicating the reception status of the signal from the key device Kd. The communication control unit F2 also provides data indicating the reception status / distance correspondence value of the signal from the key device Kd at each BLE communication device 7 to other function / circuit modules such as the position determination unit F3.

[0074] The location determination unit F3 is configured to determine the location of the key device Kd relative to the vehicle Hv based on distance correspondence values ​​observed by the BLE communication device 7. For example, the location determination unit F3 determines whether the key device Kd is located in the unlocked / unlocked area EA, the indoor area, or other areas based on the communication status with the key device Kd.

[0075] The locking / unlocking area EA is an area where the in-vehicle system 1 executes predetermined vehicle control, such as locking or unlocking doors, based on the presence of the key device Kd within the area. The locking / unlocking area EA is a type of exterior operation area and can also be called a passive entry area. For example, the locking / unlocking area EA is set to a range within a predetermined operation distance from the exterior door handles provided on the driver's door, passenger door, and trunk door. The operation distance that defines the size of the locking / unlocking area EA is, for example, 1.5 m. Of course, the operation distance may also be 1 m or 0.7 m. For security reasons, the operation distance is set to be less than 2 m. For convenience, the right locking / unlocking area EA is also referred to as the right area EA_A, the left locking / unlocking area EA is also referred to as the left area EA_B, and the rear locking / unlocking area EA is also referred to as the rear area EA_C.

[0076] The interior area corresponds to the interior of the vehicle. The interior area may be subdivided into a start-permitted area set based on the driver's seat and a start-prohibited area. The start-permitted area is an area in which the in-vehicle system 1 switches the driving power supply from off to on based on the presence of the key device Kd within that area. The start-permitted area refers to an area within the vehicle interior that is, for example, within 0.5 m of the shift lever or start button 6. The start-prohibited area refers to an area within the vehicle interior other than the start-permitted area. The interior area may be divided into a front seat area and a rear seat area. The start-permitted area can be called a passive start area.

[0077] The other area is an area outside the vehicle cabin that corresponds to the outside of the locking / unlocking area EA. The other area may be divided into a far area and an intermediate area. The far area refers to an area that is, for example, more than 6 m away from the vehicle Hv. The intermediate area refers to an area outside the vehicle cabin that is within 6 m of the vehicle Hv and is other than the locking / unlocking area EA.

[0078] The location determination unit F3 considers a key device Kd that is not connected to the communication network to be located in another area. Furthermore, if the location determination unit F3 determines that a key device Kd that is connected to the communication network is not located in either the indoor area or the locked / unlocked area EA, it determines that the key device Kd is located in another area. The locked / unlocked area EA and the indoor area correspond to the target area. Note that the target area in this disclosure can be interpreted as referring to only either the locked / unlocked area EA or the indoor area.

[0079] When determining the device location, the location determination unit F3 applies different location determination algorithms depending on whether the communication partner is the smart key 2 or the mobile terminal 3. When the communication partner is the smart key 2, the location determination unit F3 determines the location of the smart key 2 using a distance correspondence value and LF_RSSI together, as will be described separately below. On the other hand, when the communication partner is the mobile terminal 3, the location determination unit F3 makes a determination based on, for example, the distance correspondence value and BLE_RSSI without using LF_RSSI.

[0080] The location determination unit F3 may have a function to calculate the device distance, which is the distance from the BLE communication device 7 to the communication partner, based on the observed distance correspondence value as a sub-function related to determining the device location. The device distance corresponds to a parameter obtained by converting the two-frequency phase difference or the RTT into a distance dimension. The device distance is the one-way distance. In another aspect, the device distance may be the round-trip distance. The BLE communication device 7 may have a function to convert the distance correspondence value into the device distance. The device distance can also be considered as a type of distance measurement value. The method for determining the location of the smart key 2 will be described separately later.

[0081] The authentication processing unit F4 cooperates with the BLE communication device 7x to perform a process of confirming (in other words, authenticating) that the communication partner is the key device Kd. Communication for authentication is performed in an encrypted form. The authentication process itself may be performed using various methods, such as a challenge-response method. For example, the authentication processing unit F4 transmits a predetermined / randomly generated challenge code to the key device Kd. It also generates a verification code using the challenge code and key information corresponding to the device ID / key ID of the communication partner according to a predetermined procedure. It then compares the response code returned from the communication partner with the verification code and determines that the authentication is successful if the two match. This authentication process can also be referred to as a verification process, since it involves comparing the response code generated by the key device Kd based on the key information with a verification code stored or dynamically generated by the smart ECU 4. Successful authentication of the key device Kd corresponds to determining that the person attempting to access the vehicle Hv is a legitimate user.

[0082] The timing at which the authentication processing unit F4 performs the authentication processing may be, for example, the timing at which a communication connection between the BLE communication device 7 and the key device Kd is established. The authentication processing unit F4 may be configured to perform the authentication processing at a predetermined cycle while the communication connection between the BLE communication device 7 and the key device Kd is maintained. Alternatively, the authentication processing unit F4 may be configured to perform communication for the authentication processing in response to a predetermined user operation on the vehicle Hv, such as when the user presses the start button 6 or when a door is opened or closed.

[0083] The vehicle control unit F5 is configured to cooperate with the body ECU 12 and the like to execute vehicle control according to the device location and the state of the vehicle Hv, provided that authentication of the key device Kd by the authentication processing unit F4 is successful. For example, when the position determination unit F3 determines that the key device Kd is present in the locking / unlocking area EA and detects that the door button 5 has been pressed by the user, the vehicle control unit F5 cooperates with the body ECU 12 to unlock the door. When the position determination unit F3 determines that the key device Kd is present inside the vehicle cabin and detects that the start button 6 has been pressed by the user, the vehicle control unit F5 cooperates with the power supply ECU 11 to switch the running power supply from off to on.

[0084] Additionally, the smart ECU 4 registers, deletes, and disables the key device Kd based on an input signal from the input device 14. For example, the processor 41 registers / deletes the key device Kd based on a user operation. When registering a key device, the smart ECU 4 acquires the type of the device to be newly registered based on an operation signal input from the input device 14. The type information of the key device Kd acquired by the smart ECU 4 is stored in the key information storage unit M1 in association with the key information. The smart key 2 can be registered as a key device Kd, for example, at a dealership or the like.

[0085] The smart ECU 4 described above can perform map generation processing, vehicle control processing, position determination processing, and the like, as will be described below.

[0086] <About the intensity map> The intensity map stored in the intensity map storage unit M2 indicates the LF_RSSI for each relative measurement point determined with the vehicle Hv as the reference. The measurement points are arranged in a three-dimensional grid at a predetermined interval, for example, within a range of 2 m from the vehicle Hv. For example, the measurement points may be arranged at intervals of 5 cm or 10 cm in the front-rear and left-right directions, as shown in FIG. 7. The interval D between the measurement points may be another value, such as 20 cm. The measurement points may also be arranged at a predetermined interval in the vertical direction. The measurement points may be set only within the locking / unlocking area EA or the vehicle interior. The intensity map storage unit M2 may store mapped data of the LF_RSSI for each point within the locking / unlocking area EA or the vehicle interior.

[0087] In this embodiment, as an example, the intensity map includes a data set of the device distance and LF intensity range that can be observed for each measurement point, as shown in FIG. 8. Each measurement point is identified by a measurement number or coordinates. Data on the device distance for a certain point may not be a pinpoint value, but may have a certain range, such as the observed value ±0.1 m, to take into account distance measurement errors. LF intensity range data for a certain measurement point indicates the range of LF_RSSI observed by the smart key 2 when the smart key 2 is present at that measurement point. LF intensity range data is prepared for each LF transmitter 8 that is the source of transmission.

[0088] The LF intensity range data for each transmission source for the locking / unlocking area EA and the indoor area can also be called intensity condition data that indicates the LF_RSSI conditions that allow system operation for each device distance. The intensity map corresponds to the determination data. The intensity map memory unit M2 corresponds to the determination data memory unit. Note that the intensity map may be a data set that indicates the correspondence between distance-corresponding values ​​such as RTT and two-frequency phase difference and the LF intensity range for each transmission source, instead of or in parallel with the device distance.

[0089] Incidentally, when the intensity map includes data on multiple types of areas, the intensity map may also include information indicating the area type to which the corresponding point belongs. The area type is expressed, for example, by a number. For example, "1B" in FIG. 8 indicates the left area EA_B. Other areas may also be expressed as "1B" for the right area EA_A, "1C" for the rear area EA_C, "2" for indoor areas, and "0" for other areas. If the intensity map includes area type information for each measurement point, it may be possible to quickly identify which area the identified device location belongs to.

[0090] Note that the location number "100001" shown in FIG. 8 refers to, for example, measurement location k shown in FIG. 7. "ANT" in FIG. 8 is an abbreviation for antenna, and in this disclosure refers to an LF transmitter / LF antenna. For example, "ANT.A" refers to LF transmitter 8a, and "ANT.P" refers to LF transmitter 8p. "<80" written in the second line of the "ANT.A" column in FIG. 8 indicates that the reception strength of the LF signal transmitted from LF transmitter 8a is less than -80 dBm. "-10<" written in the second line of the "ANT.B" column indicates that the reception strength of the LF signal transmitted from LF transmitter 8b is greater than -10 dBm. "-50±5" indicates that the observable LF_RSSI falls within the range of -45 dBm to -55 dBm.

[0091] <Map generation process> Here, the map generation process performed by the smart ECU 4 in cooperation with the smart key 2 will be described using the flowchart shown in Fig. 9. The map generation process is a process for generating an intensity map and storing it in the intensity map storage unit M2. The map generation process can be started when, for example, a staff member at a dealership or factory performs a predetermined registration start operation on the input device 14. The map generation process includes, for example, steps S101 to S107.

[0092] Step S101 is a step for determining whether the smart key 2 has been placed at an arbitrary measurement point. The processor 41 detects that the smart key 2 has been placed at an arbitrary measurement point based on, for example, input of an operation signal indicating that placement of the smart key 2 has been completed from the input device 14. When the processor 41 detects that placement of the smart key 2 has been completed, it executes step S102.

[0093] Step S102 is a step for acquiring information on the measurement point to be registered, such as coordinates and a measurement point number. The processor 41 also acquires the information on the measurement point based on an operation by the worker / user on the input device 14. After acquiring the information on the measurement point, the processor 41 executes step S103.

[0094] Step S103 is a step of measuring LF_RSSI. Step S103 includes causing each LF transmitter 8 to transmit an LF signal (e.g., a wake signal) and causing the smart key 2 to measure the LF_RSSI for each transmission source. Step S103 also includes acquiring an observed value of LF_RSSI for each transmission source from the smart key 2 via BLE communication. After establishing a BLE communication connection with the smart ECU 4, the smart key 2 may report the observed value of LF_RSSI for each transmission source spontaneously, or may report the observed value based on receiving a transmission request from the smart ECU 4.

[0095] In step S103, the processor 41 generates LF strength range data for each transmission source at the measurement point. Note that the LF_RSSI measurement for each transmission source may be performed multiple times. The processor 41 may generate LF strength range data for each transmission source by statistically processing (e.g., averaging) the results of the multiple measurements. Once the generation of the LF strength range data for each transmission source is complete, the processor 41 executes step S104.

[0096] In step S104, the BLE communication device 7 is caused to perform ranging communication, thereby acquiring the distance from the BLE communication device 7 to the measurement point. For example, the processor 41 acquires the device distance based on the RTT and two-frequency phase difference acquired by causing the BLE communication device 7 to perform ranging communication. The distance value acquired here is a value observed during actual communication. The propagation path of a wireless signal can be longer than the straight-line distance due to, for example, detouring. By adopting the distance value observed by actually performing communication, rather than the simple straight-line distance from the mounting position of the BLE communication device 7 to the target measurement point, as the distance information to be linked to the LF strength range data, it is possible to reduce the risk of erroneously determining the device position. Once the registration of the distance information is completed, the processor 41 executes step S105.

[0097] In step S105, the LF strength range data for each transmission source observed in step S103 and the observed value of the device distance acquired in step S104 are linked to the number / coordinates of the measurement point and temporarily stored in RAM 42. In addition, processor 41 sets a value of the area type based on the number / coordinates of the measurement point. Once the linking of each data for the measurement point to be registered is completed, processor 41 executes step S106.

[0098] Step S106 is a step for determining whether or not there are any measurement points remaining for which LF_RSSI and other measurements have not yet been performed. If there are any unmeasured points remaining, the processes from step S101 onwards are executed again for those unmeasured points. On the other hand, if distance information and LF strength range data for all measurement points have been acquired, the process proceeds to step S107, where a data set obtained by packaging the data for each measurement point is registered as strength map data in the strength map storage unit M2, and this flow ends.

[0099] The map generation process may be performed for each vehicle Hv, or may be performed only for a specific vehicle. The intensity map storage unit M2 of a certain vehicle Hv may store intensity map data generated in another vehicle. Common intensity map data may be stored in smart ECUs 4 used in the same vehicle model.

[0100] <Vehicle control processing> Here, the vehicle control process performed by the smart ECU 4 will be described using the flowchart shown in Fig. 10. The vehicle control process is a process for performing vehicle control such as unlocking and locking doors and switching on / off the running power supply depending on the position of the smart key 2 or the mobile terminal 3. The vehicle control process is executed at a predetermined cycle, such as every 200 milliseconds, while the running power supply is off. Note that the vehicle control process may be triggered by detecting a user operation on the vehicle Hv, such as pressing the door button 5, pressing the start button 6, opening / closing a door, or pressing the brake pedal. The vehicle control process includes, for example, steps S201 to S211.

[0101] Step S201 is a step of causing each LF transmitter 8 to transmit a wake signal in a predetermined order. When step S201 is completed, the processor 41 executes step S202.

[0102] Step S202 is a step for searching for a key device Kd (so-called scanning). If no key device Kd is detected as a result of the scanning in step S202 (NO in S203), the process from step S204 onward is omitted and this flow ends. If a key device Kd is found as a result of the scanning in step S202, the processor 41 executes step S204.

[0103] Step S204 is a step of causing the BLE communication device 7 to establish a communication connection with the key device Kd detected by the scanning in step S202. The communication connection can be realized by sending a connection request and exchanging a response thereto. The processor 41 identifies the communication partner based on sender information contained in an advertising signal or the like. The detailed sequence from scanning to communication connection and the start of encrypted communication can be performed in accordance with the BLE standard. When the communication connection with the key device Kd is completed, the processor 41 executes step S205.

[0104] Step S205 is a step for executing communication to authenticate the wireless communication partner. For example, the processor 41 performs authentication processing of the key device Kd using the challenge code and the key information of the communication partner stored in the key information storage unit M1. If the authentication is successful (YES in S206), the processor 41 executes step S207. On the other hand, if the wireless authentication fails (NO in S206), this flow ends.

[0105] Step S207 is a step for determining whether the communication partner is the smart key 2. The processor 41 determines whether the communication partner is the smart key 2, for example, by comparing the device ID of the communication partner with the device type information for each device ID stored in the key information storage unit M1. As another aspect, the processor 41 may determine whether the communication partner is the smart key 2 by acquiring a device type code or a function code (described later) from the communication partner via BLE communication. If it is determined that the communication partner is the smart key 2 (YES in S207), the processor 41 executes step S208. If it is determined that the communication partner is not the smart key 2 (NO in S207), the processor 41 executes step S209.

[0106] Step S208 is a step for executing a smart key position determination process. The smart key position determination process will be described separately below. By executing the smart key position determination process, the processor 41 determines whether the smart key 2 as the communication partner is located in the locked / unlocked area EA, the indoor area, or another area. When step S208 is completed, the processor 41 executes step S210.

[0107] Step S209 is a step for executing a mobile terminal position determination process. The mobile terminal position determination process will also be described separately below. By executing the mobile terminal position determination process, processor 41 determines whether mobile terminal 3, which is the communication partner, is located in the locked / unlocked area EA, the indoor area, or other area. After step S209 is completed, processor 41 executes step S210.

[0108] In step S210, based on the processing results of step S208 or step S209, it is determined whether the key device Kd, which is the communication partner, is located within the operation area. The operation area here refers to an area in which vehicle control, such as unlocking, can be performed. Specifically, the lock / unlock area EA and the interior area fall under the operation area. Other areas do not fall under the operation area. Note that if the smart ECU 4 is configured with a welcome area, which is an exterior area in which exterior lighting equipment is turned on when the user approaches, the welcome area may also be included in the operation area. Furthermore, if the smart ECU 4 is configured with a remote parking area, which is an exterior area in which the vehicle Hv is semi-automatically parked remotely, the remote parking area may also be included in the operation area. The welcome area and remote parking area may be set, for example, within 6 meters of the vehicle Hv.

[0109] If the processor 41 determines that the key device Kd is located within the activation area (YES in S210), it executes vehicle control according to the device position (S211). On the other hand, if the processor 41 does not determine that the key device Kd is located within the activation area (NO in S210), it ends this flow.

[0110] Note that step S211 may be a step of transitioning to a standby state in which vehicle control can be executed in response to a user operation on a predetermined operating member, rather than executing vehicle control such as unlocking. The standby state corresponds to a state in which a user operation on an operating member corresponding to the content of vehicle control, such as door button 5, is awaited. When processor 41 detects a predetermined user operation in the standby state, it promptly executes vehicle control corresponding to the operating member or device position.

[0111] <About the location determination process for smart keys> Here, a description will be given of the location confirmation process when the communication partner is identified as the smart key 2. The smart key location determination process includes steps S301 to S307 as shown in Fig. 11. The flowchart (sequence) shown in Fig. 11 is executed as step S208 in Fig. 10.

[0112] Step S301 is a step of receiving an LF strength report, which is a data set / message indicating the LF_RSSI for each transmission source, from the smart key 2. The LF strength report itself is transmitted and received via BLE communication. The LF_RSSI for each transmission source reported here is the strength observation value of the wake signal transmitted in step S201. Note that, as another aspect, step S301 may include a step of transmitting an LF signal for LF strength measurement from each LF transmitter 8. In that case, step S301 corresponds to a step of acquiring the observation value of the reception strength of the LF signal transmitted from each LF transmitter 8 for LF strength measurement. When reception of the LF strength report is complete, the processor 41 executes step S302.

[0113] Step S302 is a step for performing a ranging process, similar to step S104. That is, the processor 41 acquires the RTT and the two-frequency phase difference by causing the BLE communication device 7 to perform ranging communication. The processor 41 also generates, as the device distance, an RTT ranging value that is a calculated value of the distance based on the observed RTT, and a phase difference ranging value that is a calculated value of the distance based on the observed two-frequency phase difference.

[0114] In FIG. 11, D_rtt denotes the RTT ranging value, and D_ΔΦ denotes the phase difference ranging value. The combination of ranging frequencies, which are frequencies used to calculate the two-frequency phase difference, may be preset or dynamically determined. The ranging frequencies may be frequencies for advertising or data communication. In BLE communication, frequency hopping is performed after a connection is established. The processor 41 may acquire the transmission / reception phase difference at the current frequency when the frequency is switched. The current frequency refers to the frequency being used (i.e., in use) at that time. For example, the processor 41 dynamically selects a combination of ranging frequencies such that the differential frequency Δf, which is the frequency difference, is 10 MHz or more and less than 70 MHz, and performs phase difference ranging. The processor 41 may calculate phase difference ranging values ​​for multiple frequency combinations. For example, the processor 41 may calculate phase difference ranging values ​​for each frequency combination from a population of four or more frequencies, and combine these to determine the final phase difference ranging value. When the distance measurement process in step S302 is completed, the processor 41 executes step S303.

[0115] Step S303 is a step of determining whether the measured RTT value (D_rtt) is less than a predetermined value. The threshold here is set to, for example, 6 m, 10 m, or 15 m. If the measured RTT value is less than the predetermined value, the processor 41 performs step S304. On the other hand, if the measured RTT value is equal to or greater than the predetermined value, the processor 41 performs step S307. Note that the measured RTT value is proportional to the RTT. Step S303 corresponds to a step of determining whether the observed RTT value is less than a predetermined value.

[0116] Note that because signals exchanged in BLE communication are longer than pulse signals such as UWB-IR, the RTT observable in BLE communication is less accurate than the RTT observable in UWB communication. Furthermore, the accuracy of distance measurement using RTT in BLE communication is not as high as distance measurement using two-frequency phase difference. For example, the RTT distance measurement value in BLE communication may contain an error of several meters. The threshold used in step S303 is preferably set to be approximately 1 to 2 meters larger than the expected maximum distance, which is the distance from the installation position of the BLE communication device 7 to the farthest point in the locking / unlocking area EA. Step S303 corresponds to a primary filter that determines whether the smart key 2 is likely to be present in the locking / unlocking area EA or inside the vehicle cabin based on the RTT distance measurement value.

[0117] Step S304 is a step for determining whether the phase difference distance measurement value (D_ΔΦ) is less than a predetermined value. The threshold here is set to the maximum expected distance, such as 5 m. Step S304 corresponds to a secondary filter that distinguishes whether the smart key 2 is likely to be present in the locked / unlocked area EA or the indoor area from the perspective of the phase difference distance measurement value. If the phase difference distance measurement value is less than the predetermined value, the processor 41 performs step S305. On the other hand, if the phase difference distance measurement value is equal to or greater than the predetermined value, the processor 41 performs step S307.

[0118] Step S305 is a step of referring to the intensity map and acquiring LF intensity range data for each sender according to the device distance acquired in the above process. If there are multiple measurement points corresponding to the device distance, all of these data are extracted. Step S305 corresponds to a step of acquiring measurement point / LF intensity range data corresponding to the observed device distance from the intensity map data using the device distance as a search key. Note that, of the RTT ranging value and the phase difference ranging value, the processor 41 adopts the phase difference ranging value as the device distance. In another aspect, the processor 41 may adopt the RTT ranging value as the device distance. Furthermore, the processor 41 may adopt the average or weighted average of the RTT ranging value and the phase difference ranging value as the device distance.

[0119] Step S306 is a step for determining the location of the smart key 2 based on the combination of the currently observed device distance and LF_RSSI for each transmission source and the intensity map. Specifically, the processor 41 compares the observed LF_RSSI value for each transmission source acquired in step S301 with the LF intensity range data for each measurement point read out in step S305, and determines whether or not there is a measurement point that matches the combination of observed values.

[0120] If there is no measurement point / dataset in the intensity map that matches the current observation results, the device location is determined to be unknown. Also, if there is a measurement point in the intensity map that matches the current observation results, the smart key 2 is determined to be located at that measurement point. Note that if there is no measurement point in the intensity map that matches the current observation results, the measurement point that is most similar to the current observation results may be determined to be the device location. Also, even if there are multiple measurement points in the intensity map that match the current observation results, the measurement point that is most similar to the current observation results is determined to be the device location.

[0121] The processor 41 determines whether the smart key 2 is located in the locking / unlocking area EA, the indoor area, or another area based on the coordinates or area type associated with the device position determined in the strength map by the above process. Determining whether the smart key 2 is located in the locking / unlocking area EA based on the reception status of the signal from the smart key 2 corresponds to determining whether the reception status of the signal from the smart key 2 satisfies a predetermined condition for determining that the smart key 2 is located in the locking / unlocking area EA. The same can be said for determining whether the smart key 2 is located in another area, such as an indoor area. The same can also be said for the mobile terminal 3.

[0122] Step S307 is a step of determining that the device location is in the other area. Step S307 may also be a step of determining that the device location is unknown. If the processor 41 determines that the device location is unknown, it may consider that the key device Kd is located in the other area. The determination result of the device location can be managed, for example, by an area flag. Here, as an example, a state in which the area flag is set to 0 corresponds to a state in which the location of the smart key 2 is determined to be in the other area / unknown. Furthermore, a state in which the smart key 2 is determined to be located in the lock / unlock area EA is expressed by area flag = 1, and a state in which the smart key 2 is determined to be located in the indoor area is expressed by area flag = 2. The area flag corresponds to a parameter that indicates the determination result of the area to which the smart key 2 belongs, in other words, the determination result of the device location.

[0123] <Location determination process for mobile devices> The mobile terminal position determination process includes steps S401 to S402 as shown in Fig. 12. The flowchart (sequence) shown in Fig. 12 is executed as step S209 in Fig. 10.

[0124] Step S401, like step S302, is a step for performing a distance measurement process. By executing this step, the processor 41 acquires an RTT distance measurement value and a phase difference distance measurement value for at least one frequency combination, and determines the device distance based on these. The processor 41 also acquires the received signal strength (BLE_RSSI) of the signal from the mobile terminal 3 from the BLE communication device 7.

[0125] Step S402 is a step of determining the device location based on a combination of the reception strength and device distance acquired in step S401. For example, if the BLE_RSSI is equal to or greater than a predetermined first strength threshold and the device distance is less than a first distance, the processor 41 determines that the device is present in an indoor area. The first distance may be set to a value obtained by adding 0.5 m to the distance from the left C-pillar, on which the BLE communication device 7 is mounted, to the steering wheel.

[0126] Furthermore, the processor 41 determines that the device is located in the left area EA_B when the BLE_RSSI is less than a predetermined second intensity threshold and the device distance is less than the second distance. The second intensity threshold may be set to a value that is a predetermined amount smaller than the first intensity threshold, taking into account that the BLE communication device 7 is disposed on the interior side of the C-pillar. The second distance may be set to a value obtained by adding a predetermined value (e.g., 0.5 m) to the distance from the left C-pillar to the outer door handle for the left front seat. Furthermore, the processor 41 determines that the device is located in the right area EA_A or the rear area EA_C when the BLE_RSSI is less than a third intensity threshold and the device distance is equal to or greater than the third distance and less than the fourth distance. The third intensity threshold may be set to a value that is equal to or smaller than the second intensity threshold, taking into account that an obstruction such as a right door exists between the left C-pillar and the right area EA_A. The third distance is set to a value obtained by subtracting a predetermined value (e.g., 0.5 m) from the distance from the left C-pillar to the right B-pillar. The fourth distance is set to a value obtained by adding a predetermined value (for example, 0.5 m) to the distance from the left C-pillar to the outer door handle for the right front seat. Note that, when it is determined that the mobile terminal 3 is present in the right area EA_A or the rear area EA_C, the processor 41 is preferably configured not to unlock the door even if the door button 5 for the left front seat is pressed.

[0127] In addition, if the combination of the observed BLE_RSSI and device distance does not satisfy the conditions for determining that the mobile terminal 3 is located in the unlocked / unlocked area EA or the indoor area, the processor 41 determines that the mobile terminal 3 is located in another area.

[0128] <Effects> If the in-vehicle system 1 is equipped with only one BLE communicator 7 and the BLE communicator 7 is located to the left or right of the center of the vehicle, such as on the left C-pillar, it is difficult to form an appropriate locking / unlocking area EA based solely on the device distance. For example, if the locking / unlocking area EA is set to be within 2 meters of the BLE communicator 7 (left C-pillar), the space that functions as the right-side area EA_A will be reduced or eliminated, which may impair the convenience of users attempting to board from the right side. Furthermore, if the locking / unlocking area EA is set to be within 4 meters of the BLE communicator 7 in order to ensure the convenience of users attempting to board from the right side, the range on the left side of the vehicle that is considered to be the locking / unlocking area EA will be larger, which may reduce the security level.

[0129] To address this issue, the processor 41 configured as described above determines the device location by combining the reception strength of the LF signal for each transmission source with the device distance, thereby enabling the processor 41 to accurately determine whether the smart key 2 is located in the unlocked / unlocked area EA or the indoor area.

[0130] More specifically, the first point k1 and the second point k2 shown in FIG. 13 are both points that are 3 m away from the BLE communication device 7. The first point k1 is located in the right-hand area, while the second point k2 is a point that belongs to the "other" area on the left side of the vehicle. Because the first point k1 and the second point k2 are both at the same distance from the BLE communication device 7, the device distances observed by ranging communication are substantially the same. Therefore, the first point k1 and the second point k2 cannot be distinguished from each other based on the device distance alone.

[0131] However, because the relative positions of the various LF transmitters 8 differ between the first point k1 and the second point k2, the LF strength of each transmitter observed by the smart key 2 may vary significantly. For example, at the first point k1, the LF_RSSI for the LF transmitter 8a may be large, while the LF_RSSI for the LF transmitter 8b may be small. On the other hand, at the second point k2, the LF_RSSI for the LF transmitter 8a may be small, while the LF_RSSI for the LF transmitter 8b may be large. Therefore, by combining the device distance with the received LF signal strength, it is possible to reduce the risk of erroneously determining that the smart key 2 is present in the lock / unlock area EA when it is not actually present therein.

[0132] Furthermore, the processor 41 changes the algorithm used to determine the device location depending on whether the communication partner is a smart key 2. This configuration makes it possible to apply an appropriate location determination algorithm depending on the functions installed in the communication partner, which is expected to improve the accuracy of location determination and eliminate unnecessary processing in the processor 41. Note that changing the determination algorithm corresponds to changing the number, combination, and parameters of communication devices used for determination.

[0133] Furthermore, when the communication partner is a mobile terminal 3 that cannot perform LF communication, the processor 41 determines the location using not only the distance measurement result from one BLE communication device 7 but also BLE_RSSI. This configuration can improve the determination accuracy compared to a configuration in which the location is determined based only on the device distance.

[0134] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, various modifications other than those described below can be implemented without departing from the gist of the present disclosure. For example, the various supplements and modifications described below can be implemented in appropriate combinations as long as no technical contradictions arise. Note that components having the same functions as the components described above are given the same reference numerals, and their description may be omitted. Furthermore, when only a portion of the configuration is mentioned, the above description can be applied to the other portions.

[0135] <Supplementary information on distance measurement using two-frequency phase difference> The value of the two-frequency phase difference makes one rotation with the difference wavelength λd corresponding to the difference frequency Δf. If the two-frequency phase difference is ΔΦ, the processor 41 cannot normally distinguish between ΔΦ and ΔΦ+2π×N (N is an integer). Therefore, a distance measurement method using the two-frequency phase difference can generally only be applied in a range where the two-frequency phase difference does not exceed 2π or 360° (i.e., one period). Furthermore, the difference wavelength λd is a parameter determined by 2π / Δf. Therefore, the distance measurement range using the two-frequency phase difference may vary depending on the combination of frequencies.

[0136] For example, when the first frequency f1 = 2402 MHz and the second frequency f2 = 2480 MHz, the differential frequency Δf = 78 MHz and the differential wavelength λd = 3.85 m. Therefore, the ranging range for this frequency combination is 3.85 m for the round-trip distance and approximately 1.93 m for the one-way distance. With this frequency combination, the processor 41 cannot distinguish between a device distance of 0.5 m and a device distance of 0.5 + 1.93 = 2.43 m.

[0137] It is preferable that the processor 41 selects a frequency combination so as to obtain a desired ranging range. For example, if a distance of 20 m is assumed as a possible distance for a BLE communication connection, the processor 41 may perform phase difference ranging using a frequency combination that provides a one-way ranging range of 20 m or more. This configuration can reduce erroneous determination of the device location due to the periodicity of the phase difference. As described above, the processor 41 may determine the device distance by combining phase difference ranging values ​​for multiple frequency combinations. This configuration can improve the accuracy of location determination while easing restrictions on the frequencies used for ranging.

[0138] As another configuration, the processor 41 may estimate the value of the aforementioned number of cycles N using RTT-based ranging values. That is, based on the RTT ranging values, it may be estimated which case of N = 0, 1, 2, 3,... the two-frequency phase difference corresponds to. Further, the processor 41 may determine the phase difference ranging value based on the estimated value of the number of cycles (N). According to this configuration, phase difference ranging may be possible even in a range exceeding the differential wavelength. This configuration corresponds to a configuration that uses the RTT ranging value as a determination material for the number of cycles (N) in phase difference ranging.

[0139] <Supplement on the Arrangement Mode of the BLE Communication Device> The in-vehicle system 1 may include a plurality of BLE communication devices 7. For example, as shown in FIG. 14, the in-vehicle system 1 may include BLE communication devices 7a, 7b, 7c, 7p, and 7x. The BLE communication device 7x is, for example, built into the smart ECU 4. The BLE communication device 7a is disposed on the outer surface portion on the right side of the vehicle Hv, and the BLE communication device 7b is disposed on the outer surface portion on the left side of the vehicle Hv. For example, the BLE communication devices 7a and 7b are disposed on the outer surface of the B-pillar or the outer door handle. The BLE communication device 7c is disposed at an arbitrary position at the rear end portion of the vehicle, such as in the trunk door or the rear bumper. The BLE communication device 7p is disposed at an arbitrary position inside the vehicle compartment, such as on the instrument panel or the center console.

[0140] Note that the B-pillar included in the vehicle Hv can be divided into a door-side B-pillar included in the door module and a vehicle-body-side B-pillar as a strut / frame including the roof portion of the vehicle body. The door-side B-pillar corresponds to a portion that abuts on the vehicle-body-side pillar in the front-seat door or the rear-seat door. The BLE communication devices 7a and 7b may be disposed in a portion of the door-side B-pillar adjacent to the side window, that is, in a resin portion above the lower end portion of the side window.

[0141] Alternatively, the in-vehicle system 1 may include a BLE communication device 7 disposed on the interior side of the driver's door, a BLE communication device 7 disposed on the interior side of the left B-pillar, or a BLE communication device 7 disposed in the trunk. The BLE communication device 7 is preferably installed in the vehicle interior at a position 0.1 m or more below the bottom edge of the side window. The in-vehicle system 1 may also include a BLE communication device 7 disposed on the ceiling of the vehicle interior.

[0142] The BLE communication device 7x is used for data communication with, for example, a key device Kd. In the present disclosure, a communication device used for data communication with the key device Kd is also referred to as a gateway communication device. The BLE communication device 7 used for data communication with the key device Kd (i.e., a gateway communication device) can also be called a representative device, a central device, a data communication device, etc. The BLE communication device 7 as a gateway communication device may be used not only for data communication but also for observing the RTT and the transmission / reception phase difference.

[0143] On the other hand, in one control mode, the processor 41 uses a BLE communicator 7 other than the BLE communicator 7x as a communicator for determining the device position / distance (i.e., for position determination). In this disclosure, the BLE communicator 7 for position determination is also referred to as a distance finder. A distance finder corresponds to a communicator for observing RTT, transmission / reception phase difference, and reception strength. In one aspect, a distance finder may correspond to a communicator that does not communicate data with the key device Kd. In the example shown in FIG. 14, the BLE communicators 7a, 7b, 7c, and 7p correspond to distance finders. Note that distance finders can also be called observation devices or satellite communicators. Of course, in another mode, the smart ECU 4 may cause each of the multiple BLE communicators 7 to communicate data with the key device Kd.

[0144] If the in-vehicle system 1 includes multiple BLE communication devices 7, the processor 41 first authenticates and identifies the communication partner using a BLE communication device 7x as a gateway communication device. If the processor 41 determines that the communication partner is the smart key 2 (FIG. 15, S501, YES), it determines the device location based on a combination of observed values ​​such as RTT at the BLE communication device 7x and the LF_RSSI for each sender (S502). Note that if the in-vehicle system 1 includes multiple BLE communication devices 7, the processor 41 only needs to cause one specific BLE communication device to perform ranging communication with the smart key 2, and that communication device does not have to be the BLE communication device 7x.

[0145] On the other hand, if the processor 41 determines that the communication partner is not the smart key 2 (S501 NO), it activates the BLE communication device 7 as a distance measuring device (S503). Then, it determines the device position based on the device distance and reception strength from multiple BLE communication devices 7 (S504). In this way, the processor 41 may change the number and type of communication devices used to determine the device position depending on whether the communication partner is the smart key 2 or not. Note that it is preferable that the distance measuring device be set to an inactive state to save power until the gateway communication device connects to the key device Kd.

[0146] According to the above configuration, when the communication partner is the smart key 2, there is no need to drive multiple distance measurement devices, so the processor 41 can reduce the frequency of activating the BLE communication device 7. Furthermore, when the communication partner is the mobile terminal 3, the distance measurement values / reception strengths of multiple BLE communication devices 7 are used to determine the device position, making it possible to improve the accuracy of estimating the position of the mobile terminal 3 compared to the above-described embodiment. Furthermore, in one operation example, the mobile terminal 3 performs distance measurement communication with multiple BLE communication devices 7, while the smart key 2 performs distance measurement communication only with the gateway communication device. From the perspective of the smart key 2, there are fewer partners with which to perform distance measurement communication than the mobile terminal 3. In other words, the smart key 2 can transmit distance measurement signals less frequently than the mobile terminal 3. Therefore, according to the above configuration, it is possible to reduce power consumption in the smart key 2 compared to the mobile terminal 3.

[0147] Note that the processing flow shown in FIG. 15 can be implemented in parallel with, in combination with, or in place of the various processes described above. As the specific processing content of step S502, a process of determining the device position using the LF intensity map can be adopted, similar to the flow shown in FIG. 11. In step S504, for example, it is determined that the mobile terminal 3 exists in an area corresponding to a communication device whose distance from the mobile terminal 3 is less than a predetermined value. For example, when the device distance based on the BLE communication device 7p is within 0.6 m, the processor 41 determines that the mobile terminal 3 exists in the indoor area. Also, when the device distance based on the BLE communication device 7a is within 0.6 m, the processor 41 determines that the mobile terminal 3 exists in the right area EA_A. When there is no BLE communication device 7 whose distance from the mobile terminal 3 is less than the predetermined value, the processor 41 may determine that the device position is in another area.

[0148] <Supplement regarding the arrangement mode of the LF transmitter> The number and arrangement mode of the LF transmitters 8 described above are examples and can be appropriately changed. For example, the LF transmitters 8a and 8b may be arranged on the outer surfaces of the B pillar and the C pillar. Also, as shown in FIG. 16, only one LF transmitter 8p of the LF transmitters 8 arranged indoors may be used. The number of LF transmitters 8 arranged in the vehicle may be three or more. The in-vehicle system 1 may include the LF transmitter 8b arranged in the trunk.

[0149] <Modification example (1)> The smart key 2 and the mobile terminal 3 may transmit a device type code as a response to an inquiry from the in-vehicle system 1. The device type code is a code indicating the device type, such as whether it is the smart key 2 or not. For example, the smart key 2 can transmit a BLE signal in which a bit string indicating that it is the smart key 2 is arranged in a data field where the device type code should be arranged, in response to an inquiry from the in-vehicle system 1. The processor 41 may use the device type code instead of the device ID to determine whether the communication partner is the smart key 2.

[0150] The smart key 2 and the mobile terminal 3 may transmit, in response to an inquiry from the in-vehicle system 1, an equipped function code indicating the variation of the communication function provided therein, together with the device type code, instead of the device type code. For example, in response to an inquiry from the in-vehicle system 1, the smart key 2 may be configured to transmit a BLE signal in which a bit string indicating that the smart key 2 has an LF receiving function is placed in a data field where the equipped function code should be placed. The processor 41 may use the equipped function code instead of the device ID to determine whether the communication partner is the smart key 2. The processor 41 may also switch the location determination algorithm depending on whether the communication partner has an LF receiving function. If the communication partner has an LF receiving function, the processor 41 may perform location determination using an intensity map, but if the communication partner does not have an LF receiving function, the processor 41 may determine the device location using a method that does not use the intensity map.

[0151] <Variation (2)> The smart ECU 4 may be configured to be able to delete / invalidate the information of the smart key 2 from the key information storage unit M1 by a user operation. Only the mobile terminal 3 may be registered as the key device Kd in the key information storage unit M1.

[0152] Although the above describes an embodiment in which the mobile terminal 3 is configured to be used as the key device Kd, this is not limiting. The smart ECU 4 may be configured to use only the smart key 2 as the key device Kd. In this case, the smart ECU 4 may be configured to end the flow if the smart key 2 cannot be found. Specifically, the processor 41 may be configured to execute the location determination process for the smart key (S208) if authentication of the communication partner is successful (YES in S206 of FIG. 10).

[0153] <Other> The smart key 2 is generally configured to operate on a primary battery. In light of this, it is preferable that power consumption at the communication partner can be reduced even further when the communication partner is the smart key 2 than when the communication partner is the mobile terminal 3. This is because primary batteries cannot be recharged. In light of this, when the communication partner is the smart key 2, the processor 41 may reduce the frequency of distance measurement communication (for example, to less than half) compared to when the communication partner is the mobile terminal 3.

[0154] The processor 41 does not necessarily need to acquire both the RTT and the transmission / reception phase difference. The processor 41 may determine the device distance based on only the RTT. The processor 41 may also calculate the device distance based on only the two-frequency phase difference without using the RTT.

[0155] The functions of the smart ECU 4 may be divided into a position determination ECU that determines the device position and a vehicle control ECU that mediates the execution of vehicle control based on the position determination result. In this case, the position determination ECU transmits a data frame indicating the position determination result of the key device Kd as a communication partner to the vehicle control ECU. For example, the data frame can be received by the vehicle control ECU via the in-vehicle network Nw. The body ECU 12 and the power supply ECU 11 are examples of vehicle control ECUs.

[0156] Alternatively, the second frequency band may be the 5.2 GHz band from 5150 MHz to 5250 MHz, or the 5.6 GHz band from 5470 MHz to 5730 MHz. The first frequency band may be any frequency band lower than the second frequency band, and the specific range may be changed as appropriate.

[0157] The smart ECU 4 and the smart key 2 may be configured to calculate at least one of the RTT and the transmission / reception phase difference using the LF signal. The first data may be data on parameters related to the time of flight (ToF) of the wireless signal, such as the reception strength, the RTT, the transmission / reception phase difference, or the two-frequency phase difference. The first data and the second data may be data on parameters whose values ​​change depending on the distance from the LF transmitter 8 and the BLE communication device 7 to the smart key 2. The first frequency band is not limited to the LF frequency band, and may be a frequency band of 900 MHz or higher. The term "device distance" in the above description may be appropriately replaced with a distance correspondence value, an RTT ranging value, a phase difference ranging value, etc. The device distance, the distance correspondence value, the RTT ranging value, the phase difference ranging value, etc. correspond to the ranging value.

[0158] <Additional remarks (1)> The present disclosure also includes the following configurations.

[0159] [Technical philosophy (1)] A processor of a mobile terminal (3), which is a general-purpose information processing terminal configured to be able to wirelessly communicate with a position determination device mounted on a vehicle, Executing a process for communication connection with a position determination device; When a communication connection with the position determination device is established, transmitting and receiving signals for distance measurement periodically or upon request from the position determination device; and transmitting a code indicating that the portable terminal is not a vehicle portable terminal based on the establishment of a communication connection with the position determination device.

[0160] The above control program is a control program for the mobile terminal 3, and the mobile terminal 3 operating in accordance with the above control program transmits a signal indicating the device type to the smart ECU 4. This configuration allows the smart ECU 4 to determine whether the communication partner is the smart key 2 or not, which is advantageous in that it can apply a determination method depending on the type of communication partner.

[0161] <Additional remarks (2)> The apparatus, system, and method described herein may be implemented by a special-purpose computer including a processor programmed to execute one or more functions embodied in a computer program. The apparatus and method described herein may also be implemented using dedicated hardware logic circuits. Furthermore, the apparatus and method described herein may also be implemented by one or more special-purpose computers configured by combining a processor executing a computer program with one or more hardware logic circuits. For example, some or all of the functions of the processor 41 may be implemented in hardware. Implementations of certain functions in hardware include implementations using one or more integrated circuits (ICs). Examples of processors (computing cores) include CPUs, MPUs, GPUs, and data flow processors (DFPs). Some or all of the functions of the processor 41 may be implemented using a system-on-chip (SoC), FPGAs, ASICs, etc. FPGA stands for Field-Programmable Gate Array. ASIC stands for Application Specific Integrated Circuit. The computer program may be stored as instructions to be executed by a computer on a computer-readable non-transitory tangible storage medium, such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory. [Explanation of symbols]

[0162] 1 In-vehicle system, 2 Smart key (vehicle portable device), 3 Portable terminal, 4 Smart ECU (position determination device), 5 Door button, 6 Start button, 7 BLE communication device (second communication device), 8 LF transmitter (first communication device), 33 Processor, 41 Processor, 221 LF strength detection unit, 721 BLE strength detection unit, Kd Key device, F1 Vehicle information acquisition unit, F2 Communication control unit, F3 Position determination unit, F4 Authentication processing unit, F5 Vehicle control unit, M1 Key information storage unit, M2 Strength map storage unit (determination data storage unit)

Claims

1. A position determination device using at least one processor connected to each of a plurality of first communication devices (8) configured to be capable of transmitting signals in a first frequency band, and at least one second communication device (7) configured to be capable of communicating with a vehicle portable device carried by a vehicle user using radio waves in a second frequency band different from the first frequency band, the second communication device is configured to be able to communicate with a portable terminal (3), which is a general-purpose information processing terminal different from the vehicle portable device, by using radio waves in the second frequency band; The processor: acquiring first data indicating a reception status of the signal transmitted by the first communication device at the vehicle portable device; acquiring second data indicating a distance from the second communication device to the vehicle portable device, the second data being determined by causing the second communication device to communicate with the vehicle portable device; determining whether the vehicle portable device is present within the target area by comparing the acquired first data and second data with determination data, which is a data set stored in a determination data storage unit (M2) and which associates the first data and the second data for each of the first communication devices that can be observed when the vehicle portable device is present within the target area; acquiring a signal indicating a device type from a communication partner in cooperation with the second communication device; determining whether the device type of the communication partner corresponds to the vehicle portable device based on the signal acquired from the communication partner; and changing an algorithm for determining the location of the communication partner depending on whether the device type of the communication partner is the vehicle portable device.

2. 2. The position determination device according to claim 1, The processor is configured to determine the location of the communication partner using the determination data when the device type of the communication partner is the vehicle portable device, and to determine the location of the communication partner without using the determination data when the communication partner is the portable terminal.

3. 3. The position determination device according to claim 1, The first data is data indicating a reception strength of a radio signal in the first frequency band observed by the vehicle portable device.

4. 4. The position determination device according to claim 1, The processor: As the second data, data indicating a round trip time, which is a time from transmitting a response request signal to the vehicle portable device to receiving a response signal from the vehicle portable device, is acquired; The location determination device is configured to determine that the vehicle portable unit is not present in a predetermined target area if the round trip time is equal to or greater than a predetermined value.

5. 4. The position determination device according to claim 1, The processor: acquiring, as the second data, data indicating a transmission / reception phase difference for each of the frequencies obtained by transmitting and receiving continuous wave signals of a plurality of frequencies belonging to the second frequency band; obtaining a phase difference distance measurement value indicating a distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency; and determining that the vehicle portable device is not present in a predetermined target area if the phase difference ranging value is equal to or greater than a predetermined value.

6. 4. The position determination device according to claim 1, The processor: acquiring, as second data, a round trip time that is a time from transmitting a response request signal to the vehicle portable device to receiving a response signal from the vehicle portable device, and a transmission / reception phase difference for each frequency that is obtained by transmitting and receiving continuous wave signals of a plurality of frequencies that belong to the second frequency band; obtaining a phase difference distance measurement value indicating a distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency; and determining that the vehicle portable device is not present in a predetermined target area if the round trip time is equal to or greater than a predetermined value, or if the phase difference ranging value is equal to or greater than a predetermined value even when the round trip time is less than the predetermined value.

7. 7. The position determination device according to claim 6, The processor is configured to perform a position determination process for the vehicle portable device using the first data, under the condition that the round trip time is less than a predetermined value and the phase difference ranging value is less than a predetermined value.

8. A position determination device using at least one processor connected to at least one first communication device (8) configured to be able to transmit signals in a first frequency band, and at least one second communication device (7) configured to be able to communicate with a vehicle portable device carried by a vehicle user using radio waves in a second frequency band different from the first frequency band, The processor: acquiring first data indicating a reception status of the signal transmitted by the first communication device at the vehicle portable device; acquiring second data indicating a distance from the second communication device to the vehicle portable device, the second data being determined by causing the second communication device to communicate with the vehicle portable device; determining a location of the vehicle portable device based on the first data and the second data; The processor further comprises: a round trip time, which is a time from transmitting a response request signal to the vehicle portable device until receiving a response signal from the vehicle portable device, and a transmission / reception phase difference for each frequency, which is obtained by transmitting and receiving continuous wave signals of a plurality of frequencies belonging to the second frequency band, as the second data; obtaining a phase difference distance measurement value indicating a distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency; determining that the vehicle portable device is not present in a predetermined target area when the round trip time is equal to or greater than a predetermined value, or when the phase difference ranging value is equal to or greater than a predetermined value even if the round trip time is less than the predetermined value; a position determination device configured to perform a position determination process of the vehicle portable device using the first data, under the condition that the round trip time is less than a predetermined value and the phase difference ranging value is less than a predetermined value.

9. 9. The position determination device according to claim 1, The processor: transmitting, from the first communication device, a wireless signal for initiating communication with the second communication device to the vehicle portable device in response to an input of a signal indicating that a predetermined operation member provided in the vehicle has been operated, or periodically; In response to the establishment of a communication connection between the vehicle portable device and the second communication device, causing the second communication device to perform distance measurement communication; and obtaining the second data as a result of the ranging communication.

10. 10. The position determination device according to claim 1, The position determination device, wherein the first frequency band is a lower frequency band than the second frequency band.

11. 11. The position determination device according to claim 1, the first frequency band is part or all of 20 kHz to 300 kHz; The position determination device, wherein the second frequency band is the 2.4 GHz band.

12. 12. The position determination device according to claim 1, The processor is a position determination device that performs predetermined vehicle control according to the position of the vehicle portable device based on the result of determining the position of the vehicle portable device.

13. 13. The position determination device according to claim 1, The position determination device is configured such that the processor transmits a data frame indicating a result of the position determination of the vehicle portable device to another device mounted on the vehicle.

14. A location determination method executed by at least one processor connected to each of a plurality of first communication devices (8) configured to be capable of transmitting signals in a first frequency band, and at least one second communication device (7) configured to be capable of communicating with a vehicle portable device and a portable terminal using radio waves in a second frequency band different from the first frequency band, acquiring, from the vehicle portable device, first data indicating a reception status at the vehicle portable device of a signal transmitted from the first communication device; acquiring second data indicating a distance from the second communication device to the vehicle portable device, the second data being determined by causing the second communication device to communicate with the vehicle portable device; determining whether the vehicle portable device is present within the target area by comparing the acquired first data and second data with determination data, which is a data set stored in a determination data storage unit (M2) and which associates the first data and the second data for each of the first communication devices that can be observed when the vehicle portable device is present within the target area; acquiring a signal indicating a device type from a communication partner in cooperation with the second communication device; determining whether the device type of the communication partner corresponds to the vehicle portable device based on the signal acquired from the communication partner; changing an algorithm for determining the location of the communication partner depending on whether the device type of the communication partner is the vehicle portable device or not.

15. A location determination method executed by at least one processor connected to and used with at least one first communication device (8) configured to be able to transmit signals in a first frequency band, and at least one second communication device (7) configured to be able to communicate with a vehicle portable device carried by a user of the vehicle using radio waves in a second frequency band different from the first frequency band, comprising: acquiring, from the vehicle portable device, first data indicating a reception status at the vehicle portable device of a signal transmitted from the first communication device; acquiring second data indicating a distance from the second communication device to the vehicle portable device, the second data being determined by causing the second communication device to communicate with the vehicle portable device; determining a location of the vehicle portable device based on the first data and the second data; acquiring, as second data, a round trip time that is a time from transmitting a response request signal to the vehicle portable device to receiving a response signal from the vehicle portable device, and a transmission / reception phase difference for each frequency that is obtained by transmitting and receiving continuous wave signals of a plurality of frequencies that belong to the second frequency band; acquiring a phase difference ranging value indicating a distance from the second communication device to the vehicle portable device based on the transmission / reception phase difference for each frequency, Determining the location of the vehicle portable device includes: determining that the vehicle portable device is not present in a predetermined target area when the round trip time is equal to or greater than a predetermined value, or when the phase difference ranging value is equal to or greater than a predetermined value even if the round trip time is less than the predetermined value; and performing a position determination process for the vehicle portable device using the first data, under the condition that the round trip time is less than a predetermined value and the phase difference ranging value is less than a predetermined value.

16. a position determination device (4) including at least one processor (41) connected to and used with at least one first communication device (8) configured to be capable of transmitting signals in a first frequency band and at least one second communication device (7) configured to be capable of performing wireless communication using radio waves in a second frequency band different from the first frequency band; a vehicle portable device (2) that is a dedicated device for a user to operate a vehicle, the vehicle portable device (2) being configured to receive a signal transmitted from the first communication device and to be able to perform wireless communication using the second frequency band; a mobile terminal (3) that is a general-purpose information processing terminal configured to be able to perform wireless communication using the second frequency band, The vehicle portable device includes: activating the position determination device based on reception of a signal in the first frequency band and initiating a wireless communication connection using radio waves in the second frequency band with the position determination device; transmitting data indicating a reception strength of a signal in the first frequency band in the wireless communication using the second frequency band; transmitting a code indicating that the device type is the vehicle portable device based on the establishment of a communication connection with the position determination device; transmitting and receiving a signal for distance measurement with the second communication device when a communication connection with the position determination device is established; The mobile terminal performing a process for communication connection with the position determination device using radio waves in the second frequency band; transmitting and receiving a signal for distance measurement with the second communication device when a communication connection with the position determination device is established; transmitting a code indicating that the device type is not the vehicle portable device based on the establishment of a communication connection with the position determination device; The position determination device acquiring second data indicating a distance from the second communication device to a communication partner, the second data being determined by causing the second communication device to perform a predetermined distance measurement communication; obtaining a signal indicating a device type from a communication partner using the second communication device; determining whether the device type of the communication partner corresponds to the vehicle portable device based on the signal acquired from the communication partner; When the device type of the communication partner is the vehicular portable device, first data indicating a reception status of the vehicular portable device in response to a signal transmitted from the first communication device is acquired from the vehicular portable device as the communication partner; and if the device type of the communication partner is the vehicle portable device, determining the location of the vehicle portable device based on the first data and the second data.

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