Position determining device, position determining system, and position determining method

Abstract

According to the present invention, a vehicle-mounted key system includes: a GW module configured to be capable of performing data communication with a key device; an anchor configured to be capable of performing ranging communication; and a main controller configured to execute processing relating to determining the position of the key device on the basis of the result of the ranging communication. When the GW module is communicatively connected to a mobile device, the main controller promptly transmits a signal to the anchor instructing the anchor to perform periodic ranging communication with the mobile device. Meanwhile, when the GW module is communicatively connected to a dedicated device, ranging communication is not performed immediately, but upon establishment of another prescribed ranging condition, a signal is subsequently transmitted to the anchor instructing the anchor to perform ranging communication with the dedicated device.

Description

Position determination device, position determination system, and position determination method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-123720 filed in Japan on July 30, 2024, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to techniques for determining the location of a key device relative to an object (e.g., a vehicle).

[0003] Systems are widely used in which a vehicle-mounted communication device communicates with a dedicated key to determine the position of the dedicated key relative to the vehicle and then unlock / lock the vehicle, etc. Such systems are known as smart entry systems or PEPS (passive entry / passive start) systems.

[0004] In recent years, systems that allow general-purpose mobile devices such as smartphones to be used as vehicle key devices in addition to dedicated keys have been put into practical use. For example, Patent Document 1 discloses a configuration in which a vehicle starts wireless communication to determine the location of a mobile device after establishing a communication connection with the mobile device via Bluetooth (registered trademark) Low Energy (hereinafter, Bluetooth LE). In Patent Document 1, multiple sensors mounted on the vehicle and a mobile device perform ranging communication using UWB (Ultra Wide Band) communication to determine the location of the mobile device relative to the vehicle.

[0005] The term "dedicated key" as used herein refers to a dedicated device that functions as a vehicle key and may be called a key fob, smart key, key card, etc. The term "key device" refers to a device that functions as a vehicle key and is used to verify the legitimacy of the person attempting to use the vehicle. The term "mobile device" may be understood to mean a general-purpose communication terminal with specific wireless communication capabilities, such as a smartphone, tablet, or wearable device.

[0006] Patent No. 7085526

[0007] Like the portable device, the dedicated key may be configured to establish a communication connection with the in-vehicle system via Bluetooth LE and then perform ranging communication via UWB. However, the battery capacity of the dedicated key may be smaller than that of the portable device. If a specific type of communication device with a relatively small battery capacity, such as a dedicated key, is configured to communicate using the same specifications as a portable device (e.g., a smartphone), the battery may run out more frequently.

[0008] One objective of the present disclosure is to provide techniques that can reduce power consumption in certain types of devices used in position determination systems.

[0009] One position determination device disclosed herein is a position determination device that determines the position of a key device relative to an object, and includes a memory unit that stores information on communication devices registered as key devices, and a control unit that executes processing to determine the position of the key device using a plurality of communication units configured to be able to perform wireless communication with the key device, the plurality of communication units including a first communication unit configured to be able to perform data communication with the key device according to a predetermined first communication protocol, and a second communication unit configured to be able to perform ranging communication with the key device according to a predetermined second communication protocol, and the memory unit stores information on communication devices of the first device type as key devices. The control unit is configured to be able to register both a first type device, which is a communication device of a first device type, and a second type device, which is a communication device of a second device type, and the control unit is configured to perform the following operations: based on the first communication unit having established a communication connection with the second type device, send to the second communication unit a signal instructing it to perform ranging communication with the second type device; based on the first communication unit having established a communication connection with the first type device and a predetermined ranging condition being met, send to the second communication unit a signal instructing it to perform ranging communication with the first type device; and acquire a result of the ranging communication from the second communication unit and determine the position of the key device that has established ranging communication with the second communication unit.

[0010] The location determination system included in the present disclosure is a location determination system that determines the location of a key device relative to an object, and includes: a storage unit that stores information on communication devices registered as key devices; a first communication unit that is configured to be able to perform data communication with the key device according to a predetermined first communication protocol; a second communication unit that is configured to be able to perform ranging communication with the key device according to a predetermined second communication protocol; and a control unit that executes a process of determining the location of the key device that is communicatively connected to the first communication unit using the second communication unit, and the storage unit stores information on communication devices of the first type that are registered as key devices. The control unit is configured to be able to register both a key device that is a first type device and a second type device that is a communication device of a second device type, and the control unit is configured to transmit, to the second communication unit, an instruction to perform ranging communication with the second type device based on the first communication unit having established a communication connection with the second type device, transmit, to the second communication unit, an instruction to perform ranging communication with the first type device based on the first communication unit having established a communication connection with the first type device and a predetermined ranging condition being satisfied, and obtain a result of the ranging communication from the second communication unit and determine the position of the key device that performed ranging communication with the second communication unit.

[0011] The present disclosure includes a location determination method executed by a computer for determining the location of a communication device registered as a key device, the location determination method comprising the steps of: communicating with a first communication unit configured to be able to perform data communication with the key device according to a predetermined first communication protocol; acquiring data of a connected device that is a key device connected to the first communication unit; communicating with a second communication unit configured to be able to perform ranging communication with the key device according to a predetermined second communication protocol; accessing a storage unit that stores information on the communication device registered as a key device; and identifying the device type of the connected device. determining a location of the key device that performed the ranging communication with the second communication unit, and when the first communication unit has connected to and communicated with a first type device that is a communication device of a first device type, subsequently transmitting a signal to the second communication unit instructing it to perform ranging communication with the first type device based on the establishment of a predetermined ranging condition; and when the first communication unit has connected to and communicated with a second type device that is a communication device of a second device type, transmitting a signal to the second communication unit instructing it to perform ranging communication with the second type device even if the ranging condition is not established; and obtaining a result of the ranging communication from the second communication unit, and determining the location of the key device that performed ranging communication with the second communication unit.

[0012] According to the above technology, when the communication device to which the first communication unit is connected for communication is a second type device, ranging communication is performed even if the ranging condition is not met. On the other hand, when the communication device to which the first communication unit is connected for communication is a first type device, ranging communication is not performed simply by connecting to the first communication unit. When the communication device to which the first communication unit is connected for communication is a first type device, ranging communication is performed when a predetermined ranging condition is met after connecting to the first communication unit. Therefore, the frequency with which the first type device performs ranging communication is less than the frequency with which the second type device performs ranging communication. The lower the frequency with which ranging communication is performed, the lower the power consumption. Therefore, it is possible to reduce power consumption in a communication device of the first device type as a specific type.

[0013] Note that the symbols in parentheses in the claims indicate a correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of the present disclosure.

[0014] 1 is a diagram for explaining an overall view of a vehicle electronic key system. FIG. 2 is a block diagram showing the configuration of an in-vehicle key system and a key device. FIG. 3 is a diagram showing an example of an anchor mounting position. FIG. 4 is a flowchart for explaining the operation of a DK-ECU. FIG. 5 is a time chart for communication in a standby state. FIG. 6 is a time chart for communication after a user action is detected. FIG. 7 is a flowchart for retrying triggered ranging. FIG. 8 is a time chart for a case where triggered ranging includes performing ranging communication multiple times. FIG. 9 is a time chart for communication after a user action is detected when connected to multiple dedicated devices for communication.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments. The configurations disclosed below may be modified in various ways without departing from the spirit of the present disclosure. Various modified examples may be appropriately combined as long as no technical contradictions arise. The present disclosure also includes configurations that are not explicitly stated and are formed by combining multiple modified examples. In the following description, components having the same function may be given the same reference numerals, and specific descriptions thereof may be omitted. Furthermore, components having the same function may be given the same or similar names, and specific descriptions thereof may be omitted. When only a portion of a configuration is mentioned, descriptions given elsewhere may apply to other parts.

[0016] <Overall Configuration> One embodiment of a vehicle electronic key system according to the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the schematic configuration of a vehicle electronic key system. As shown in FIG. 1, the vehicle electronic key system includes a vehicle key system 1 and one or more key devices 9. The key device 9 is a communication device that functions as a key for the vehicle Hv. Information about the key device 9 (e.g., a device ID) is pre-registered in the vehicle key system 1. The key device 9 may be understood as a communication device that is pre-registered as a vehicle key.

[0017] In the vehicle key system 1 of this embodiment, multiple dedicated devices 7 are registered as key devices 9. Specifically, three dedicated devices 7A, 7B, and 7C are registered as key devices 9 in the vehicle key system 1. The dedicated devices 7 are dedicated devices that serve as electronic keys for the vehicle hybrid. The dedicated devices 7 may be called smart keys, key fobs, key cards, access keys, etc. The dedicated devices 7 may be transferred to the owner along with the vehicle hybrid when the vehicle hybrid is purchased. The dedicated devices 7 may have various shapes, such as a flat rectangular parallelepiped shape, a flat ellipsoid shape (a so-called fob type), or a card shape. The dedicated devices 7 are accessories to the vehicle hybrid. Therefore, the dedicated devices 7 may also be referred to as accessory keys, accessory devices, etc. The dedicated devices 7 correspond to a first-device-type communication device, i.e., a first-type device.

[0018] In addition, multiple portable devices 8 are registered in the vehicle key system 1 of this embodiment. Specifically, three portable devices 8A, 8B, and 8C are registered in the vehicle key system 1 as key devices 9. The portable devices 8 are general-purpose information processing terminals carried by the user of the vehicle Hv. The portable devices 8 may be communication terminals equipped with specific wireless communication functions, such as smartphones, wearable devices, or tablets. The portable devices 8 correspond to communication devices of a second device type, i.e., second-type devices. In the present disclosure, devices that are linked to the vehicle key system 1 and function as vehicle keys, such as the dedicated device 7 and the portable devices 8, are collectively referred to as key devices 9.

[0019] In other embodiments, the number of dedicated devices 7 registered in the vehicle key system 1 may be one or zero. Also, in other embodiments, the number of portable devices 8 registered in the vehicle key system 1 may be one or zero. However, at least one dedicated device 7 or portable device 8 is registered as a key device 9 in the vehicle key system 1.

[0020] As shown in Figures 1 and 2, the vehicle key system 1 includes a digital key ECU (hereinafter referred to as DK-ECU) 2 and multiple anchors 3. ECU stands for Electronic Control Unit. DK stands for Digital Key. Information about the key device 9 may be registered in the DK-ECU 2.

[0021] The vehicle key system 1 and the key device 9 are compatible with multiple communication methods. For example, the DK-ECU 2 and the key device 9 are configured to be able to implement short-range communication as a first communication method. Short-range communication is communication that complies with a predetermined short-range wireless communication standard, with a practical communication distance of 1 m to 30 m, and up to approximately 100 m. In this embodiment, the short-range communication standard is Bluetooth (registered trademark) Low Energy (hereinafter, Bluetooth LE). Communication that complies with the Bluetooth LE standard will also be referred to as LE communication below. Hereinafter, an LE signal refers to a wireless signal transmitted and received via LE communication. The terms short-range communication and LE communication may be replaced with SRWC (Short Range Wireless Communication). The LE signal may be replaced with an SRWC signal.

[0022] The LE signal includes information indicating the source or destination. The source and destination of the LE signal may be expressed, for example, by a device ID. The DK-ECU 2 and the key device 9 are paired in advance and each holds its own device ID.

[0023] The anchor 3 and the key device 9 are also configured to be able to implement UWB (Ultra Wide Band) communication as a second communication method. The UWB communication may be wireless communication using the UWB-IR (Impulse Radio) method. That is, the anchor 3 and the key device 9 are configured to be able to transmit and receive pulsed radio waves (hereinafter, UWB pulses) used in UWB communication. The UWB pulses used in UWB communication may be signals having an extremely short pulse width (e.g., 2 nanoseconds) and a bandwidth of 500 MHz or greater (i.e., ultra-wide bandwidth).

[0024] Hereinafter, a radio signal using UWB pulses transmitted and received in UWB communication will be referred to as a UWB signal. If data can be superimposed on one UWB pulse, the UWB signal may be a single UWB pulse. The UWB signal may also be a pulse sequence signal including multiple UWB pulses. The UWB signal may include data indicating the sender. The anchor 3 and key device 9 perform ranging communication using UWB signals. Ranging communication is communication that measures the distance between communication devices. Details of ranging communication will be described separately below.

[0025] <Key Device> As described above, the key device 9 is a communication terminal equipped with an LE communication function and a UWB communication function. Regardless of the device type, the dedicated device 7 and the portable device 8 serving as the key device 9 each include a key controller 90, a first communication module 91, and a second communication module 92.

[0026] The key controller 90 controls the operations of the first communication module 91 and the second communication module 92. The key controller 90 is configured as a computer including a processor 901, a memory 902, a storage 903, an input / output circuit, and the like. The storage 903 stores the device ID of the key device 9, a key code used in authentication processing with the DK-ECU 2, and the like. The key code is a confidential code for verifying the authenticity of the key device 9. The storage 903 also stores a passcode used in encrypted communication with the DK-ECU 2. The passcode is data equivalent to a Passkey. The passcode may be exchanged using an OOB (Out of Band) method, in which codes are exchanged using a communication means other than an LE link, such as NFC or transponder communication. The exchange and registration of the passcode may be performed during pairing processing (strictly speaking, bonding processing).

[0027] In addition, application software (digital key app) that enables the key device 9 to function as a key for the vehicle hybrid vehicle is installed in the storage 903. The digital key app is a program for secure communication with the DK-ECU 2 and for responding to inquiries and requests from the DK-ECU 2. The processor 901 executes the digital key app, thereby enabling the key device 9 to function as such. In the dedicated device 7, the digital key app may be implemented as embedded software. In the portable device 8, the digital key app may be pre-installed as one of the apps that the portable device 8 can execute, or may be installed by the user.

[0028] The first communication module 91 is a wireless communication module for LE communication provided in the key device 9. The first communication module 91 may include an LE antenna and an RF (Radio Frequency) core. The LE antenna is an antenna element for transmitting and receiving radio waves in the frequency band used for LE communication (here, the 2.4 GHz band). There may be one or more LE antennas. The RF core is a circuit module that performs processing related to the transmission and reception of radio signals. The RF core demodulates a signal received by the LE antenna and provides it to the key controller 90. The RF core also modulates transmission data input from the key controller 90 and radiates it as radio waves from the LE antenna.

[0029] The first communication module 91 transmits and receives LE signals under the control of the key controller 90. For example, when the key device 9 is not connected to the DK-ECU 2, the key controller 90 uses the first communication module 91 to perform LE advertising. Advertising is a process of transmitting an advertising signal using a predetermined channel. The advertising signal is a wireless signal used to notify other devices of its presence. When the DK-ECU 2 receives an advertising signal from the key device 9, it may transmit a connection request in response. When the key controller 90 receives a connection request from the DK-ECU 2, the first communication module 91 communicates with the DK-ECU 2. Based on the communication connection with the vehicle key system 1, the key controller 90 may perform authentication processing using LE communication, exchanging ranging settings, and ranging communication using UWB. The wireless authentication processing may be performed, for example, using a challenge-response method.

[0030] The second communication module 92 is a communication module for performing UWB communication. The second communication module 92 includes an antenna for UWB communication, a transmitting / receiving circuit, and a UWB controller 311. The transmitting / receiving circuit is a circuit that performs signal processing related to modulation and demodulation. The UWB controller 311 is a microcomputer. The UWB controller 311 executes processing for ranging communication. The processing for ranging communication may include waiting for reception at a predetermined timing according to ranging setting data provided in advance from the vehicle key system 1, and returning a UWB signal as a response signal upon receiving a UWB signal for ranging.

[0031] For example, when the second communication module 92 receives a UWB signal as a polling signal from the vehicle key system 1, it returns a UWB signal modulated with a code including its own device ID to the vehicle key system 1. The polling signal is a signal used by the vehicle key system 1 to search for the key device 9. The polling signal is a type of signal that requests the key device 9 to return a response signal. The second communication module 92 may be configured to operate in accordance with a predetermined UWB ranging communication sequence.

[0032] The second communication module 92 may be configured to start up based on instructions from the key controller 90, perform distance measurement communication, and then stop operation. The key controller 90 stops the second communication module 92 if an LE communication connection (hereinafter also referred to as an LE link) with the DK-ECU 2 is not established. The key controller 90 starts the second communication module 92 when an LE link with the DK-ECU 2 has been established. This configuration reduces power consumption during standby.

[0033] The dedicated device 7 and portable device 8 serving as the key device 9 each include the key controller 90, first communication module 91, and second communication module 92 described above. In addition to the above, the dedicated device 7 and portable device 8 may also include an acceleration sensor, an NFC module, and a battery. The acceleration sensor is a sensor that detects acceleration. The NFC module is a communication module for implementing near field communication (NFC). NFC is a communication method with a communication distance of several centimeters to approximately 10 cm. In terms of the communication distance, NFC and the near field communication of the present disclosure may be considered to be different (different) communication methods. The NFC module may include a coil / loop antenna, etc.

[0034] Generally, the battery of the portable device 8 is a secondary battery. That is, the portable device 8 may be configured to operate on a secondary battery. On the other hand, the dedicated device 7 may be configured to operate on a primary battery. From one perspective, the key device 9 that operates on a primary battery may be considered the dedicated device 7. Of course, the dedicated device 7 may also be configured to operate on a secondary battery. A key device 9 with a smaller battery capacity than the portable device 8 (for example, less than half) may also be considered the dedicated device 7.

[0035] The dedicated device 7 may be configured to enter sleep mode when the acceleration sensor does not detect acceleration (in other words, vibration) equal to or greater than a certain value. Sleep mode may be a state in which the first communication module 91 and the second communication module 92 are stopped. The dedicated device 7 may wake up based on the detection of vibration by the acceleration sensor, and may return to sleep mode after attempting to connect to the DK-ECU 2 for a certain period of time. Of course, once connected to the DK-ECU 2, the dedicated device 7 may maintain normal mode until a stationary state is maintained for a certain period of time. The normal mode here may be a state in which the first communication module 91 is operating.

[0036] The portable device 8 serving as the key device 9 may include a touch panel, a display, or the like. The portable device 8 serving as the key device 9 may also include a cellular communication module. The cellular communication module is a communication module that implements cellular communication such as 4G or 5G. The portable device 8 may be configured to obtain a key code for authentication processing with the DK-ECU 2 from a specific server (e.g., a digital key server) and store the key code in the storage 903.

[0037] <DK-ECU> The DK-ECU 2 is connected to an in-vehicle network that is established as a communication network within the vehicle Hv. Standards for in-vehicle networks include Controller Area Network (CAN: registered trademark), Ethernet (registered trademark), and FlexRay (registered trademark). The DK-ECU 2 is connected to each of the multiple anchors 3 via the in-vehicle network or via a dedicated communication cable. The DK-ECU 2 is also connected to the action sensor 4 via a dedicated cable or the in-vehicle network.

[0038] The DK-ECU 2 is mounted at any position in the vehicle hybrid. As an example, the DK-ECU 2 is attached to the left C-pillar of the vehicle hybrid (see FIG. 4). The C-pillar is the third pillar from the front among the pillars provided on the vehicle hybrid. The DK-ECU 2 may also be located in the instrument panel, the overhead console, the right C-pillar, under the driver's seat, or the like.

[0039] The DK-ECU 2 controls multiple anchors 3. Working in cooperation with the multiple anchors 3, the DK-ECU 2 functions as a location determination device that determines the location of the key device 9 (hereinafter, referred to as the device location). The device location refers to the relative location of the key device 9 with respect to the vehicle hybrid. Because the key device 9 is linked to a user, determining the device location corresponds to determining the user location. The DK-ECU 2 may be configured to unlock the vehicle hybrid when it determines that the key device 9 is present in a pre-defined entry area for the vehicle hybrid and receives a predetermined unlocking operation. The entry area may be an area within a predetermined distance (e.g., 1.5 m) from the vehicle hybrid. The DK-ECU 2 may also be configured to turn on the vehicle power when it determines that the key device 9 is present inside the vehicle (particularly near the driver's seat) and receives a predetermined power-on operation.

[0040] The DK-ECU 2 includes a gateway module 21, an in-vehicle communication circuit 22, and a main controller 23. Hereinafter, gateway may be abbreviated as GW. For example, a GW module refers to a gateway module. The GW module 21 corresponds to a first communication unit.

[0041] The GW module 21 is a wireless communication module provided in the DK-ECU 2 and configured to be able to perform LE communication. The configuration and functions of the GW module 21 may be the same as those of the first communication module 91. The GW module 21 is supplied with power from the vehicle battery even when the vehicle power supply is set to off. The GW module 21 is in a standby state constantly or intermittently using the power supplied from the vehicle battery even when the vehicle Hv is parked. The GW module 21 periodically scans and attempts to connect to the key device 9.

[0042] The GW module 21 may include a GW controller 211, which is a microcomputer that executes processing related to LE communication. The GW controller 211 controls the exchange of data with the main controller 23. Upon connection with the key device 9, the GW controller 211 performs procedures such as starting encrypted communication with a connected device. The connected device here refers to the key device 9 with which an LE communication connection has been established. The GW module 21 does not necessarily have to be built into the DK-ECU 2. The GW module 21 may be provided outside the DK-ECU 2. In this case, the GW module 21 and the DK-ECU 2 may be connected to each other so as to be able to communicate with each other via a dedicated communication line or an in-vehicle network.

[0043] The in-vehicle communication circuit 22 is a circuit that performs signal processing related to data communication between the main controller 23 and the anchor 3. The in-vehicle communication circuit 22 includes a PHY chip and a cable connector that comply with the communication method of the anchor 3. The in-vehicle communication circuit 22 converts signals input from the anchor 3 into a format that can be received by the main controller 23, and outputs the signals to the main controller 23. The in-vehicle communication circuit 22 performs predetermined signal processing on the data input from the main controller 23, and outputs the data to the anchor 3.

[0044] The main controller 23 is hardware that controls the operation of the DK-ECU 2. The main controller 23 includes a processor 231, a memory 232, a storage 233, an input / output circuit, etc. The storage 233 stores anchor position data that indicates the mounting position of the anchor 3 in the vehicle Hv. The storage 233 also stores a position determination program that causes the processor 231 to execute processing related to determining the device position.

[0045] The main controller 23 functions as a computer that executes various processes related to determining the device position by having the processor 231 execute a position determination program. Execution of the position determination program by the processor 231 corresponds to the execution of a position determination method. The functions of the DK-ECU 2 described below are basically provided by the main controller 23. In other embodiments, the main controller 23 may be integrated into the gateway controller 211. The gateway controller 211 may be configured to execute processes related to controlling the anchor 3 and determining the device position. The functional layout within the vehicle key system 1 may be changed as appropriate. The DK-ECU 2, the main controller 23, or the gateway controller 211 corresponds to the control unit. The vehicle key system corresponds to the position determination system.

[0046] The main controller 23 includes a key data storage unit 2331. The key data storage unit 2331 may be realized using a part of the storage area of ​​the storage 233. In another embodiment, the key data storage unit 2331 may be realized using a non-volatile storage medium that is physically independent from the storage 233. The key data storage unit 2331 is configured to allow the processor 231 to write, read, delete, and so on data.

[0047] The key data storage unit 2331 is a storage medium for saving information about the key device 9 used as a key for the vehicle Hv. The key data storage unit 2331 stores device information for each key device 9. The device information may include a key number, a user ID, a device type, a device ID, and a key code. The key number may correspond to the order in which the key devices 9 were registered. The user ID is an identifier for identifying multiple users and is set for each user. The device type refers to the type (or classification) of the key device 9, such as whether it is a dedicated device 7 or a portable device 8. The dedicated device 7 corresponds to a first type device, and the portable device 8 corresponds to a second type device.

[0048] The vehicle Hv may be a service car provided for a car sharing service, etc. The DK-ECU 2 installed in the service car may obtain in advance device information of the portable device 8 linked to the user who has reserved use from a digital key server that issues key codes, and store the information in the key data storage unit 2331. The device information for each key device 9 may be linked to information such as expiration date, authority, and seat position.

[0049] The main controller 23 may have an active state and a power saving state as power states. The active state refers to a state in which power is supplied to the main controller 23 and various processes such as position determination can be executed. The power saving state may be, for example, a so-called power-off state in which power supply to the main controller 23 is completely cut off. The main controller 23 transitions from the active state to the power saving state when a state in which the GW module 21 is not connected to any key device 9 continues for a predetermined time. The main controller 23 may transition from the power saving state to the active state when the GW module 21 is connected via LE communication with at least one key device 9.

[0050] The power saving state may be a sleep state or a hibernation state instead of a power-off state. The sleep state refers to a state in which the supply of power to the processor 231 is stopped while the data being worked on, in other words, the execution state of a program, is stored in a volatile memory such as a RAM. The hibernation state refers to a state in which the supply of power to the processor 231 and memory 232 is stopped while the execution state of a program is stored in a writable non-volatile memory such as a flash memory.

[0051] <Anchor> The anchor 3 is a device used to determine the device position. The anchor 3 performs distance measurement communication with the key device 9 using UWB communication based on instructions from the DK-ECU 2. The anchor 3 includes a UWB module 31 and an in-vehicle communication circuit 32. The anchor 3 corresponds to a second communication unit.

[0052] The UWB module 31 is a wireless communication module provided in the anchor 3 and configured to be able to perform UWB communication. The configuration of the UWB module 31 may be substantially the same as that of the second communication module 92. The UWB module 31 includes an antenna for UWB communication, a transmitting / receiving circuit, a UWB controller 311, etc. The transmitting / receiving circuit is a circuit that performs signal processing related to modulation and demodulation in UWB communication. The UWB controller 311 is a microcomputer that controls the operation of the UWB module 31 and generates UWB ranging data, which will be described next.

[0053] The UWB module 31 performs a ranging process based on an instruction from the DK-ECU 2. The ranging process is a process for generating a ranging value based on the propagation time (in other words, the flight time) of a UWB signal from the UWB module 31 to the key device 9. The ranging process may include a step of performing ranging communication with the key device 9 and a step of calculating the distance based on the result of the ranging communication.

[0054] Ranging communication includes a step in which a communication device serving as an initiator transmits a poll signal, and a step in which a communication device serving as a responder transmits a response signal upon receiving the poll signal. The poll signal is a UWB signal with a predetermined pattern that requests the responder to return a response. The response signal is a UWB signal serving as a response signal, and may be referred to as an answer signal. In this disclosure, UWB signals for ranging, such as poll signals and response signals, are also referred to as UWB ranging signals or simply ranging signals. The ranging signal may include information indicating a destination or a sender.

[0055] Here, the anchor 3 corresponds to the initiator, and the key device 9 is configured to act as the responder. The roles of initiator and responder in ranging communication may be reversed. Furthermore, ranging communication may include a step in which the initiator transmits a final signal upon receiving a response signal. The UWB signal exchanged between the UWB module 31 and the key device 9 in ranging communication may be a single impulse signal, or may be a pulse sequence signal in which multiple impulse signals are arranged in a predetermined pattern.

[0056] The UWB controller 311 measures the round trip time (RTT), which is the time elapsed from transmitting a poll signal to receiving a response signal from the key device 9, and generates a ranging value based on the RTT. The ranging value represents the distance from the anchor 3 to the key device 9. The RTT corresponds to the round-trip flight time of the UWB signal. The RTT takes a value corresponding to the distance from the UWB module 31 to the key device 9. In this embodiment, the UWB controller 311 calculates the ranging value by multiplying half of the value obtained by subtracting a predetermined correction value from the RTT by the propagation speed of the radio waves. The correction value here is a parameter for offsetting the response processing time in the key device 9 and the delay time within the UWB module 31. The specific value of the correction value can be designed as appropriate. The correction value may even be 0.

[0057] The distance measurement value may also be referred to as device distance, etc. Data indicating the distance measurement value is UWB distance measurement data. If no response is received from the key device 9 in the distance measurement communication, the UWB module 31 may output an error value, which is a specific value indicating that measurement was not possible, as the distance measurement value. The error value may be, for example, Nan (Not a Number). The error value may be a sufficiently large predetermined value. The error value may also be an error code, etc. The UWB module 31 transmits the generated UWB distance measurement data to the DK-ECU 2. Since the flight time corresponds to the distance, the distance measurement value may be the RTT itself. The DK-ECU 2 may perform the process of converting the RTT to the distance.

[0058] The in-vehicle communication circuit 32 is a circuit that performs signal processing related to the transmission and reception of signals between the anchor 3 and the main controller 23. The in-vehicle communication circuit 32 converts the signal input from the DK-ECU 2 into a format that can be received by the UWB module 31, and outputs it to the UWB module 31. The in-vehicle communication circuit 32 performs predetermined signal processing on the data input from the UWB module 31, and outputs it to the DK-ECU 2.

[0059] The anchor 3 described above operates according to instructions received from the DK-ECU 2. The anchor 3 starts up based on instructions from the DK-ECU 2 and performs ranging communication. After performing ranging communication, the anchor 3 stops operating either spontaneously or based on instructions from the DK-ECU 2. The anchor 3 transmits a poll signal or waits for a response from the key device 9 at a timing according to the ranging setting data received from the DK-ECU 2. The anchor 3 may include a communication module for LE communication in addition to the UWB module 31. The anchor 3 may also be configured to perform CS ranging, which will be described later.

[0060] <Position of anchors> As shown in Figure 3, the vehicle Hv is equipped with a plurality of anchors 3A, 3B, 3C, 3D, 3P, and 3Q. The number of anchors 3 equipped on the vehicle Hv and the arrangement of each anchor 3 may be changed as appropriate for each vehicle model. The configuration, function, and performance of the plurality of anchors 3A to 3D, 3P, and 3Q may be substantially the same. Of the plurality of anchors 3, anchors 3A to 3D are outdoor units or exterior anchors, and are attached to the exterior surface of the vehicle Hv. In contrast, anchors 3P and 3Q are indoor units or interior anchors, and are attached to the interior of the vehicle Hv.

[0061] The anchor 3A is disposed at the left front corner of the vehicle Hv. Specifically, the anchor 3A is disposed near the left front wheel, at the left end of the front bumper, at the left side mirror, etc. Such an anchor 3A may be referred to as the left front anchor, the first anchor, etc. The anchor 3B is disposed at the right front corner of the vehicle Hv. Specifically, the anchor 3B is disposed near the right front wheel, the right end of the front bumper, the right side mirror, etc. Such an anchor 3B may be referred to as the right front anchor, the second anchor, etc.

[0062] Anchor 3C is disposed at the right rear corner of vehicle Hv. Specifically, anchor 3C is disposed near the right rear wheel and at the right end of the rear bumper, etc. Such anchor 3C may be referred to as the right rear anchor, the third anchor, etc. Anchor 3D is disposed at the left rear corner of vehicle Hv. Specifically, anchor 3D is disposed near the left rear wheel and at the left end of the rear bumper, etc. Such anchor 3C may be referred to as the left rear anchor, the fourth anchor, etc.

[0063] Anchor 3P and anchor 3Q are arranged offset in the front-to-rear direction in the vehicle interior. Anchor 3P is mounted forward of anchor 3Q. Specifically, anchor 3P is arranged on the instrument panel, the upper edge of the windshield, the center console, etc. Anchor 3P may be referred to as the interior front anchor, the fifth anchor, etc. On the other hand, anchor 3Q is mounted rearward of anchor 3P. Specifically, anchor 3Q is arranged on the center of the rear seat, the ceiling above the rear seat, the trunk, etc. Anchor 3Q may be referred to as the interior rear anchor, the sixth anchor, etc.

[0064] <Action Sensor> The action sensor 4 is a sensor for detecting a user action with respect to the vehicle Hv. A user action can also be referred to as an operation or instruction from the user. The action sensor 4 may be, for example, a door sensor, a power switch, a brake pedal sensor, or a seat sensor. The door sensor is a sensor for detecting a user operation for unlocking and locking the doors of the vehicle Hv. The door sensor may be a touch sensor or a push-type switch provided on an outer door handle.

[0065] The power switch is a push switch that the user uses to turn the vehicle power on and off. The power switch may also be called a start switch. The brake pedal sensor is a sensor that detects the amount of depression of the brake pedal. The seating sensor is a sensor that detects whether the driver is seated in the driver's seat and may actually be a load sensor or the like.

[0066] The user actions that the DK-ECU 2 detects may include locking and unlocking operations, sitting down, power-on operations, depressing the brake pedal, and opening and closing doors. An unlocking operation is an operation for unlocking the vehicle Hv. A locking operation is an operation for locking the vehicle Hv. A power-on operation is an operation for switching the vehicle power supply from off to on. The DK-ECU 2 may detect a touch operation on a door sensor as an unlocking / locking operation. A power-on operation may be pressing the start switch.

[0067] The user action to be detected may include waving a foot over a detection area formed below the door. In this case, the action sensor 4 may be an infrared sensor, a photoelectric sensor, or a sonar sensor provided near the side sill. The action sensor 4 outputs an operation signal corresponding to the user's operation to the DK-ECU 2.

[0068] The user action may be a gesture of a predetermined pattern, such as moving a hand in a predetermined pattern. The DK-ECU 2 may be compatible with a gesture control system that opens and closes a door using gestures. The action sensor 4 may be a sensor capable of detecting gestures of a predetermined pattern, such as a camera or a proximity sensor. Furthermore, the user action may be the utterance of a predetermined voice phrase (e.g., "open"). The action sensor 4 may be a voice recognition system including a microphone configured to collect voices near the door.

[0069] The DK-ECU 2 detects a user operation (i.e., a user action) on the vehicle Hv based on an input signal from the action sensor 4. The DK-ECU 2 is configured to execute distance measurement communication with the dedicated device 7 as described below based on the detection of a predetermined user action.

[0070] One or more other ECUs, such as a body ECU, may be present between the DK-ECU 2 and the action sensor 4. The DK-ECU 2 may receive data indicating that a user action has been performed from the other ECU. The body ECU is an ECU that controls body-related actuators such as the door lock motor, window motor, side mirror motor, and headlamp.

[0071] In addition to the anchor 3 and the action sensor 4, various other in-vehicle devices may be directly or indirectly connected to the DK-ECU 2. For example, the DK-ECU 2 may be connected to a power supply ECU, a cellular module, an NFC module, etc., so that they can communicate with each other via an in-vehicle network or using a dedicated cable. The power supply ECU is an ECU that controls the on / off of the vehicle power supply installed in the vehicle hybrid. The vehicle power supply is a power source for running the vehicle hybrid, and if the vehicle hybrid is an engine vehicle, it refers to the ignition power supply. If the vehicle hybrid is an electric vehicle, the vehicle power supply refers to the system main relay.

[0072] <Communication Flow> Upon receiving an advertising signal from an unconnected device, the DK-ECU 2 executes the distance measurement-related process illustrated in FIG. 4. Here, the unconnected device refers to a key device 9 registered in the DK-ECU 2 that has not yet established an LE communication link with the DK-ECU 2. The distance measurement-related process may include steps S101 to S113, as shown in FIG. 4. The DK-ECU 2 as the entity executing the following process may be replaced with the vehicle key system 1, main controller 23, processor 231, gateway controller 211, etc. The functional layout may be changed as appropriate, and the vehicle key system 1, DK-ECU 2, main controller 23, processor 231, and gateway controller 211 may be replaced with each other.

[0073] In step S101, the DK-ECU 2 establishes a communication connection with an unconnected device 9 based on receiving a signal (e.g., an advertising signal) from the unconnected device. Step S101 may include exchanging signals such as a scan request, a scan response, and a connection request in a predetermined procedure. The key device 9 established a communication connection in step S101 is also referred to as the target device in the following flow.

[0074] When the communication connection with the target device is completed, the DK-ECU 2 performs preparation for encrypted communication in step S102. Preparation for encrypted communication may involve exchanging encryption keys, etc., and may be performed in a predetermined sequence. Preparation for encrypted communication may include performing two-way communication multiple times. Preparation for encrypted communication may require a time equivalent to seven connection intervals.

[0075] When the DK-ECU 2 and the key device 9 are connected for communication, they communicate data at predetermined intervals. The data communication interval may also be referred to as a connection interval (CI). The connection interval may be set within a range conforming to the LE communication standard, such as 30 milliseconds or 40 milliseconds. Periodic LE communication performed according to the connection interval is also referred to as periodic LE communication. Furthermore, the opportunity (i.e., timing) for periodic data communication determined according to the connection interval is also referred to as a periodic communication opportunity. During a periodic communication opportunity with no particular communication content, the DK-ECU 2 and the key device 9 may transmit and receive a PDU (Protocol Data Unit) with an empty payload, known as an Empty PDU. In one aspect, the transmission and reception of an Empty PDU may be interpreted as communication for confirming the connection.

[0076] Furthermore, since frequency hopping is employed in LE communication, the channel used for data communication changes over time (for example, at each periodic communication opportunity). LE communication uses multiple channels belonging to the 2.4 GHz band. Of the multiple channels allocated to LE communication, the channel used for actual communication (in other words, the operating frequency / operating channel) changes over time due to frequency hopping. The amount of channel transition may be defined by a hop increment. The hop increment is a parameter indicating the amount of frequency change when switching frequencies. The hop increment may be any value, such as 5 channels or 7 channels. LE communication settings such as the connection interval, hop increment, and initial channel may be exchanged during pairing or when the LE link is established.

[0077] After the LE link is established, when preparations for encrypted communication are complete, the DK-ECU 2 starts encrypted communication with the target device. Note that if encryption keys have already been exchanged or if encrypted communication is to be performed using a bonded passcode or the like, the DK-ECU 2 may start encrypted communication immediately after the LE link is established. Step S102 may be a step in which communication is performed between the DK-ECU 2 and the connected device to agree to start encrypted communication.

[0078] When encrypted communication begins, the DK-ECU 2 performs authentication processing with the target device via LE communication in step S103. The authentication processing is a process for verifying the authenticity of the communication device connected to the DK-ECU 2 as the key device 9. The authentication processing may be performed using a challenge-response method. The authentication processing may include a process in which the DK-ECU 2 transmits a challenge code to the connected device, and a process in which the target device generates a response code using the challenge code and key code received and returns the response code to the in-vehicle system VS. The DK-ECU 2 verifies the response code received from the connected device using the key code stored in the storage 233, thereby confirming the authenticity of the communication partner. Note that the authentication processing in step S103 is an optional element and may be omitted.

[0079] When the authentication process is completed, in step S104, the DK-ECU 2 exchanges ranging settings with the target device via LE communication. The ranging settings are a data set that defines the specifications of ranging communication. The ranging settings include parameters that determine the timing of executing ranging communication. In other words, the ranging settings include data for specifying the timing of executing ranging communication relative to a reference time or a ranging start time. The timing of executing ranging communication in ranging communication can be determined using time slots that divide time into fixed time intervals. The execution timing of ranging communication, in other words, the transmission time of a UWB ranging signal, may be expressed by a slot number.

[0080] The reference time is a reference point on the time axis. The distance measurement setting itself does not need to include specific time information indicating the reference time. The transmission time of a trigger signal, which will be described later, may be applied as the reference time. The device receiving the trigger signal (i.e., the key device 9) uses the reception time of the trigger signal as the reference time.

[0081] The ranging start time is a second reference point determined based on the reference time. The ranging start time may be set any time after the reference time. The ranging start time defines the position of the 0th time slot. The point in time corresponding to the ranging start time is also referred to as UWB Time Zero. As described below, ranging communication with the portable device 8 is repeatedly and periodically performed. The ranging settings may include the number of regular ranging times, which is the maximum number of times ranging communication is performed, and the regular ranging interval, which is the interval between regular ranging communication executions. The number of regular ranging times corresponds to the second number.

[0082] As will be described later, the trigger signal for defining the reference time may include, as correction information, information instructing that a predetermined time after or before the reception time be regarded as the reference time, instead of the reception time. When the key device 9 receives a trigger signal including correction information, the key device 9 may be configured to regard the reception time corrected with the correction information as the reference time, instead of the reception time of the trigger signal. The DK-ECU 2 and the key device 9 may be configured to hold a common reference time, and the specific method for determining the reference time may be changed as appropriate.

[0083] When the exchange of the distance measurement settings is completed, the DK-ECU 2 notifies each anchor 3 of the distance measurement settings in step S105. Step S105 may include activating anchors 3 that are currently out of operation. The notification of the distance measurement settings to the anchors 3 may be performed using a distance measurement instruction signal, which will be described later. For example, the distance measurement instruction signal may include the distance measurement settings.

[0084] In step S106 following step S105, it is determined whether the device type of the target device is the dedicated device 7. The device type here may be divided into the dedicated device 7 and other devices (i.e., the portable device 8). The DK-ECU 2 of this embodiment changes the execution mode of the ranging communication depending on whether the target device is the dedicated device 7 or not. The device type of the target device may be identified by comparing the device ID of the target device with the device information stored in the key data storage unit 2331.

[0085] If the target device is the portable device 8 (NO in S106), the DK-ECU 2 executes processing to start ranging communication in step S107. The processing to start ranging communication includes transmitting a trigger signal to the target device and transmitting a ranging instruction signal to the anchor 3. As described above, the trigger signal is a signal for sharing a common reference time / ranging start time between the target device and the vehicle key system 1. If the trigger signal does not include correction information, the sender of the trigger signal operates using the transmission time of the trigger signal as the reference time. Furthermore, the receiver of the trigger signal operates using the reception time of the trigger signal as the reference time. Such a trigger signal functions as a signal notifying / requesting that ranging communication will be performed a predetermined time from now. The trigger signal may be called a UWB trigger request, etc.

[0086] The ranging instruction signal transmitted from the DK-ECU 2 to the anchor 3 is a signal instructing the anchor 3 to perform ranging communication with the target device. The ranging instruction signal may be a signal instructing the anchor 3 to operate in accordance with ranging settings using the current time as the reference time. By transmitting the ranging instruction signal, the anchor 3 performs ranging communication using the reference time (and therefore the ranging start time) that is common to the target device.

[0087] The trigger signal may be transmitted to the target device at the next regular communication opportunity determined by the connection interval. The ranging instruction signal may be transmitted to the anchor 3 approximately simultaneously with the transmission of the trigger signal to the target device. However, the transmission of the trigger signal and the ranging instruction signal may be slightly delayed. The anchor 3 and the target device may be configured to have a common ranging start time through LE communication. The ranging instruction signal may include data that enables the anchor 3 to identify the ranging start time for the target device.

[0088] Step S108, which follows step S107, is a step in which distance measurement communication is performed at a timing specified in the distance measurement setting. Distance measurement communication with the portable device 8 is performed repeatedly approximately periodically until a predetermined termination condition is met. That is, upon receiving and transmitting a trigger signal, the vehicle key system 1 starts periodic distance measurement communication with the portable device 8 registered as the key device 9.

[0089] In the periodic ranging communication, the vehicle key system 1 and the portable device 8 repeatedly perform ranging communication a predetermined number of times according to the ranging setting. The number of periodic ranging may be set to, for example, 20, 30, or 40. The periodic ranging interval may be set to any value, preferably 400 milliseconds or less, such as 180 milliseconds, 280 milliseconds, or 320 milliseconds. One ranging communication may include the target device performing ranging communication with multiple anchors 3 individually (sequentially). The target device may also be configured to perform ranging communication with multiple anchors 3 in parallel.

[0090] Step S109 is a step for determining whether or not a termination condition is met. The termination condition may be, for example, that distance measurement communication has been performed a number of times specified in the distance measurement setting. The DK-ECU 2 may increment the number of distance measurements each time step S108 is performed, and determine that the termination condition is met when the number of distance measurements reaches the maximum number of times. The number of distance measurements here refers to the number of times distance measurement communication has been performed. The termination condition may be that the LE communication connection has been disconnected. The termination condition may be that the vehicle power supply has been turned on from off, or that the vehicle Hv has started moving. The termination condition may be that a certain amount of time has elapsed since the vehicle Hv was locked or unlocked.

[0091] In step S109, if the termination condition is met (YES in step S109), the periodic distance measurement communication with the portable device 8 as the target device is terminated. On the other hand, if the termination condition is not met, the process returns to step S108, and step S108 is executed at a predetermined periodic distance measurement interval.

[0092] The DK-ECU 2 may determine the device location based on the results of the ranging communication each time ranging communication with the target device is performed. The results of ranging communication may be distance measurements observed at each of the multiple anchors 3. The DK-ECU 2 may determine the presence area of ​​the key device 9 based on the mounting positions of each anchor 3 and the distance measurements. The presence area is determined based on the vehicle Hv. The presence area may be divided into three categories: interior, entry area, and other, or may be further subdivided. The presence area may be determined by calculating the position coordinates of the key device 9 relative to the vehicle Hv using the principle of multipoint positioning (e.g., three-point positioning) based on the mounting positions and distance measurements of each anchor 3.

[0093] As described above, if the key device 9 connected for communication is a portable device 8 (NO in S106), the DK-ECU 2 transmits a trigger signal to the target device via LE communication as soon as distance measurement communication preparations are complete, and starts periodic distance measurement communication. Furthermore, if the DK-ECU 2 is connected for communication with multiple portable devices 8, it periodically performs distance measurement communication with each of the connected portable devices 8 in turn. Hereinafter, the term "periodic distance measurement communication" may be abbreviated to "periodic distance measurement." The term "periodic distance measurement" may be replaced with "periodic distance measurement communication." As described above, the number of periodic distance measurements is set to four or more times, such as 20 or 30 times.

[0094] On the other hand, if the key device 9 connected for communication with the DK-ECU 2 is the dedicated device 7 (YES in S106), the DK-ECU 2 does not immediately perform distance measurement communication with the dedicated device 7 even if the distance measurement communication is ready. The DK-ECU 2 temporarily transitions to a standby state (S110). In the standby state, the DK-ECU 2 is ready for distance measurement communication with the dedicated device 7, but the distance measurement communication with the dedicated device 7 is on hold. The standby state may be maintained until a user action is detected or a certain period of time has elapsed. Note that even in the standby state, periodic distance measurement with the portable device 8 may be performed. Whether the DK-ECU 2 is in the standby state may be managed using a flag or the like.

[0095] In the standby state, the DK-ECU 2 monitors the output signal of the action sensor 4 received by the in-vehicle communication circuit 22 and determines whether a user action has been performed. Determining that a user action has been performed corresponds to detecting a user action. When the DK-ECU 2 detects a user action in the standby state (YES in S111), it transmits a trigger signal to the dedicated device 7 as the target device via LE communication and also transmits a distance measurement instruction signal to the anchor 3. As a result, the vehicle key system 1 performs distance measurement communication with the dedicated device 7 only once (S112). The detection of a user action corresponds to the establishment of the distance measurement condition.

[0096] When the DK-ECU 2 detects a user action in the standby state, it may re-authenticate the dedicated device 7 before transmitting the trigger signal. Step S103 may be inserted between step S111 and step S112. By performing authentication processing when a user action is detected, it is possible to prevent spoofing, etc. In other words, the security of the vehicle Hv may be improved. The authentication processing associated with the detection of a user action may also be performed on the portable device 8.

[0097] As described above, the DK-ECU 2 of this embodiment repeatedly performs distance measurement communication with the portable device 8. This allows the position of the portable device 8 to be tracked and its relative position with respect to the vehicle Hv to be managed with high accuracy. Meanwhile, the DK-ECU 2 limits the circumstances in which distance measurement communication with the dedicated device 7 is performed to when the user operates the vehicle Hv, and also limits the number of distance measurements to one. This reduces the number of times the dedicated device 7 performs distance measurement communication, thereby reducing the power consumption of the dedicated device 7. In other words, the battery life of the dedicated device 7 can be extended.

[0098] Furthermore, the DK-ECU 2 performs distance measurement communication with the dedicated device 7B at least when a user action is performed. This makes it possible to determine the position of the dedicated device 7B relative to the vehicle Hv when the user action is performed. If the dedicated device 7B is located within a predetermined distance from the vehicle Hv, the DK-ECU 2 receives the determination result of the device position and the detection result of the user action and executes a predetermined system response, such as unlocking. This embodiment makes it possible to extend the battery life of the dedicated device 7 while avoiding a decrease in user convenience or system responsiveness.

[0099] <Distance Measurement Timing According to Device Type> Here, the execution timing of distance measurement communication according to device type (hereinafter also referred to as distance measurement timing) will be described using Figure 5. Figure 5 shows the flow of UWB communication between each key device 9 and the vehicle key system 1 in a situation where three portable devices 8 (8A, 8B, and 8C in the figure) and one dedicated device 7 (7A in the figure) are connected to the DK-ECU 2 via LE communication. Figure 5 also shows the operation of each device in an action standby state. The standby state refers to a situation where the DK-ECU 2 is in a standby state, i.e., a situation where at least one dedicated device 7 has already established an LE connection with the DK-ECU 2 and no user action has been detected.

[0100] In the action standby state, the vehicle key system 1 does not perform distance measurement communication with the dedicated device 7A, but periodically performs distance measurement communication with the connected portable device 8. In the anchor 3, the state in which distance measurement communication with the portable device 8 is periodically performed may be referred to as a CCC mode.

[0101] 5, when multiple portable devices 8 are connected to the vehicle key system 1 via LE communication, the vehicle key system 1 repeatedly performs ranging communication in a predetermined order with each of the multiple portable devices 8 using a different time slot. In FIG. 5, the time region separated by a dashed line represents one time slot.

[0102] In this embodiment, the timing of distance measurement with the portable device 8 may be managed using a single (common) time axis maintained by the vehicle key system 1. In other words, the entire system including the vehicle key system 1 and multiple portable devices 8 may have a single reference time for distance measurement communication. The DK-ECU 2 may transmit, to each portable device 8, a trigger signal including correction information set so that the start points of blocks on the multiple portable devices 8 coincide. This allows the start times of blocks on the multiple portable devices 8 to be synchronized.

[0103] A block here refers to a group of multiple time slots. The multiple time slots that make up one block may be managed by slot number. A time slot with slot number 1 refers to the time slot at the beginning of the block. A portable device 8 connected to the vehicle key system 1 may be configured to perform one distance measurement communication in one block. The number of regular distance measurements may be interpreted as a parameter that defines the number of blocks in one cycle. One cycle is a group of multiple blocks.

[0104] The DK-ECU 2 assigns ranging slots to each portable device 8 so that the ranging timing for each portable device 8 is staggered. The ranging slots are time slots for performing ranging communication. If the number of time slots constituting one block is K (K>10) and the slot numbers assigned to portable devices 8A, 8B, and 8C are 1, 3, and 5, respectively, ranging communication with portable device 8A is performed in the 1+K×nth time slot. Ranging communication with portable device 8B is performed in the 3+K×nth time slot. Ranging communication with portable device 8C is performed in the 3+K×nth time slot.

[0105] Here, "n" is an integer equal to or greater than 0 and can be 0, 1, 2, ..., j, j+1, j+2, .... "j" is also an arbitrary natural number. The number of time slots (K) constituting one block may be interpreted as a parameter defining the periodic ranging interval. The number of time slots defining one block may also be included in the ranging configuration. The length (i.e., width) of one time slot may also be included in the ranging configuration. The width of a time slot may be set to any value, such as 12 milliseconds, 24 milliseconds, 36 milliseconds, or 60 milliseconds. "Tp" in FIG. 5 represents the length of one block, or in other words, the periodic ranging interval. FIG. 5 illustrates an example in which the periodic ranging interval is 280 milliseconds.

[0106] The DK-ECU 2 may manage the number of distance measurements individually for each portable device 8. For example, it is possible that portable device 8A first establishes a communication connection with the DK-ECU 2, and then portable device 8B establishes an LE connection with the DK-ECU 2. In this case, the periodic distance measurement with portable device 8A may end earlier than the periodic distance measurement with portable device 8B. Even after the periodic distance measurement with portable device 8A ends, the DK-ECU 2 may continue the periodic distance measurement with portable device 8B. In other embodiments, the DK-ECU 2 may continue the periodic distance measurement with other portable devices 8 until the end condition for the distance measurement communication with the portable device 8 that connected last is met.

[0107] Figure 6 shows the operation of the vehicle electronic key system when a user action (e.g., touching the steering wheel) is detected at time Ta in the action waiting state described in Figure 5. For convenience of illustration, the width of each time slot in Figure 6 is drawn narrower than in Figure 5.

[0108] When the DK-ECU 2 detects a steering wheel touch as a user action at time Ta, it performs communication to authenticate the dedicated device 7 as an optional element. Communication C1 in the figure is communication in which the DK-ECU 2 transmits a challenge code to the dedicated device 7A, and the dedicated device 7A returns a response (so-called ACK) indicating successful reception. Communication C2 in the figure is communication in which the DK-ECU 2 transmits a message to the dedicated device 7A requesting the return of a response code, and the dedicated device 7A returns a message including the response code. Communications C1 and C2 may be performed using a periodic communication opportunity determined by a connection interval. Communication C2 may be integrated with communication C1, and the dedicated device 7A's response to the challenge code in communication C1 may be to transmit a response code instead of an ACK.

[0109] If the DK-ECU 2 successfully authenticates the dedicated device 7A, it transmits a trigger signal to the dedicated device 7A. Furthermore, the DK-ECU 2 transmits a distance measurement instruction signal to the anchor 3 at approximately the same time as transmitting the trigger signal. Communication C3 in the figure is communication in which the DK-ECU 2 transmits a trigger signal to the dedicated device 7A via LE communication, and the dedicated device 7A returns an Ack. The DK-ECU 2 performs distance measurement communication by considering the time when it transmits the trigger signal to the dedicated device 7A as the reference time, and the dedicated device 7A also considers the time when it receives the trigger signal from the DK-ECU 2 as the reference time.

[0110] Due to signal propagation time and reception processing delays, the reference time recognized by the DK-ECU 2 and the reference time recognized by the dedicated device 7A may differ by a few microseconds, to be precise. However, this time error can be ignored because it is sufficiently small compared to the width of the time slot and the width of the waiting time for receiving UWB pulses (the so-called reception window).

[0111] As described above, the communications C1 and C2 for authentication after detecting a user action are optional and may be omitted. The DK-ECU 2 may transmit a trigger signal to the dedicated device 7A promptly after detecting a user action, for example, at the next regular communication opportunity determined by the connection interval.

[0112] The vehicle key system 1 and the dedicated device 7A exchange ranging settings, including ranging timing relative to a reference time, with the dedicated device 7A in advance LE communication (e.g., S104). The reference time for the dedicated device 7 in the vehicle key system 1 may be different from the reference time for the portable device 8. The vehicle key system 1 may be configured to perform ranging communication with the dedicated device 7 according to the reference time for the dedicated device.

[0113] The ranging standby time, which is the standby time from the reference time until ranging communication, may be set to 30 milliseconds, 40 milliseconds, 50 milliseconds, or the like. In FIG. 6 , the ranging standby time is represented by β. The set value of the ranging standby time (β) may be included in a data set of ranging settings exchanged in advance. The set value of the ranging standby time (β) may also be included in a trigger signal. When the dedicated device 7 receives a trigger signal including the set value of the ranging standby time, it may perform ranging communication according to the ranging standby time specified in the trigger signal.

[0114] The vehicle key system 1 transmits a UWB pulse to the dedicated device 7A, for example, after a distance measurement standby time (β) has elapsed from the reference time, and begins distance measurement communication with the dedicated device 7A. The dedicated device 7A enters a state in which it can receive UWB pulses (i.e., a standby state) once the distance measurement standby time has elapsed from the reference time, and begins distance measurement communication with the vehicle key system 1. C4 in the figure indicates distance measurement communication between the vehicle key system 1 and the dedicated device 7A. In this embodiment, distance measurement communication between the vehicle key system 1 and the dedicated device 7A is completed in one go and is not repeated.

[0115] According to this embodiment, there are few opportunities for ranging communication between the vehicle key system 1 and the dedicated device 7 (specifically, only one). Therefore, it is desirable to avoid conflict between ranging communication between the vehicle key system 1 and the dedicated device 7 and ranging communication with another key device 9. Therefore, when the DK-ECU 2 detects a user action, it suspends (i.e., temporarily stops) periodic ranging with the connected portable device 8 until a predetermined resumption condition is met. Specifically, the DK-ECU 2 transmits a predetermined suspend command to each anchor 3, thereby stopping transmission of UWB pulses from the anchor 3 to the portable device 8. The DK-ECU 2 also transmits a ranging suspend signal to the connected portable device 8 via LE communication. The ranging suspend signal is an LE signal requesting that ranging communication be suspended.

[0116] The ranging pause signal may include a resume condition. The resume condition may be included in the ranging setting. The resume condition may be set so that the resume timing occurs after ranging communication with the dedicated device 7 is completed. The resume condition may be that a ranging pause signal (described later) has been transmitted or received, or that a certain time (e.g., 20 milliseconds) has elapsed since the ranging pause signal was transmitted or received. Alternatively, the resume condition may be that a certain time (e.g., 200 milliseconds) has elapsed since the ranging pause signal was received. Paradoxically, ranging communication with the dedicated device 7 may be designed to be completed within the pause period of regular ranging.

[0117] In this way, the DK-ECU 2 can reduce the risk of failure in distance measurement communication with the dedicated device 7 by temporarily pausing periodic distance measurement with the portable device 8 in response to a user action. In one aspect, this configuration can be interpreted as a configuration that prioritizes distance measurement communication with the dedicated device 7, which is rarely performed (in other words, spot distance measurement communication), over periodic distance measurement with the portable device 8.

[0118] Communication C5 in FIG. 5 illustrates communication in which the vehicle key system 1 transmits a ranging pause signal to each portable device 8, and the portable device 8 returns an Ack. While FIG. 5 illustrates only one communication C5 including transmission of a ranging pause signal, the vehicle key system 1 may transmit the ranging pause signal individually to each portable device 8. The ranging pause signal may be transmitted using a periodic communication opportunity determined by the connection interval. The ranging pause signal may be transmitted as soon as possible after detecting a user action. For example, the ranging pause signal may be transmitted within 100 milliseconds after detecting a user action. While FIG. 5 illustrates a pattern in which the ranging pause signal is transmitted between communications C1 and C2, the ranging pause signal may be transmitted before communication C1 or between communications C2 and C3. The ranging pause signal may be transmitted before transmitting a trigger signal to the dedicated device 7A.

[0119] Note that, when the vehicle key system 1 is the initiator of UWB ranging, the portable device 8 also does not return a UWB ranging signal unless the vehicle key system 1 transmits a UWB ranging signal. Therefore, the vehicle key system 1 can essentially pause periodic ranging with the portable device 8 by stopping transmission of ranging signals to the portable device 8, without transmitting a ranging pause signal to the portable device 8. However, if the ranging pause signal is not transmitted, the portable device 8 periodically enters a standby state for a ranging signal, which may result in unnecessary power consumption in the portable device 8. From the perspective of reducing power consumption in the portable device 8, the DK-ECU 2 may transmit a ranging pause signal to the connected portable device 8 upon detecting a user action.

[0120] When the DK-ECU 2 completes distance measurement communication with the dedicated device 7, it transmits a distance measurement resume signal to the connected portable device 8. The distance measurement resume signal is a signal notifying the resumption of paused periodic distance measurement. The distance measurement resume signal corresponds to a resume instruction. The DK-ECU 2 notifies the anchor 3 of a resume command, which is a signal instructing the anchor 3 to resume periodic distance measurement with the portable device 8. This resumes periodic distance measurement between the portable device 8 and the vehicle key system 1.

[0121] The ranging resume signal may include a resume waiting time (γ) that is the remaining time until the periodic ranging is resumed. When each portable device 8 receives a ranging resume signal including the resume waiting time, it may resume periodic ranging according to the resume waiting time specified in the ranging resume signal. The timing of LE communication may differ for each portable device 8. The DK-ECU 2 may transmit a ranging resume signal specifying a different resume waiting time for each portable device 8.

[0122] Communication C6 in the figure is communication in which the vehicle key system 1 transmits a ranging resume signal to the connected portable device 8, and the portable device 8 returns an Ack. Although Fig. 5 shows only one communication C6 including transmission of a ranging resume signal, the vehicle key system 1 may transmit a ranging resume signal individually to each portable device 8. The ranging resume signal may be transmitted using an opportunity to communicate with the portable device 8 determined by the connection interval. The ranging resume signal may include the remaining time until restart.

[0123] In another embodiment, the DK-ECU 2 may transmit, as the ranging pause signal, a signal including a set value of a total pause time, which is a waiting time for resumption starting from the time of reception of the ranging pause signal. Each portable device 8 may resume periodic ranging when the total pause time notified in advance has elapsed since the suspension of periodic ranging. The total pause time may be set to a value, such as 200 milliseconds, that is sufficiently large compared to the time required for ranging communication with the dedicated device 7. In this case, transmission and reception of the ranging resume signal may be omitted.

[0124] The length of the pause period during which periodic ranging with the portable device 8 is paused is determined based on the number of LE communications between the DK-ECU 2 and the dedicated device 7 and the ranging wait time (β) for the dedicated device 7, and can be less than a certain value. If the worst-case time from the detection of a user action to the transmission of a trigger signal to the dedicated device 7A is T1, T1 can be considered to be three connection intervals. Furthermore, the time for one ranging communication corresponds to the time slot width and is a default value (T2) of several tens of milliseconds. If the time from the completion of ranging communication with the dedicated device 7 to the resumption of periodic ranging with the portable device 8 is T3, T3 can be set as a design value. For example, T3 may be set to one or two connection intervals, assuming a sufficient time to transmit a ranging resume signal to the portable device 8. Given the above circumstances, the length of the pause period may be estimated as T1 + β + T2 + T3.

[0125] The pause command sent from the DK-ECU 2 to the anchor 3 upon detection of a user action corresponds to a signal that switches the operation mode of the anchor 3 from CCC mode to dedicated mode. As described above, the CCC mode is a mode in which periodic ranging communication is performed with the portable device 8. The dedicated mode is an operation mode in which periodic ranging communication is not performed, but intensive ranging communication is performed only with the dedicated device 7 a predetermined number of times (for example, once). In this way, the anchor 3 may have two operation modes: the CCC mode and the dedicated mode. The dedicated mode may also be referred to as a key fob mode, a smart key mode, etc.

[0126] In the above configuration, the vehicle key system 1 does not perform periodic distance measurement with the dedicated device 7 when the vehicle is in an action standby state, but instead performs distance measurement communication with the dedicated device 7 when triggered by a user operation (in other words, an action) on the vehicle hybrid. This reduces the number of times the dedicated device 7 performs distance measurement communication, thereby extending the battery life of the dedicated device 7. Note that distance measurement communication triggered by a user operation on the vehicle hybrid can be called trigger distance measurement.

[0127] Furthermore, when the DK-ECU 2 causes the anchor 3 to perform ranging communication with the dedicated device 7, it temporarily suspends the periodic ranging with the portable device 8. Then, when the ranging communication with the dedicated device 7 is completed, the DK-ECU 2 resumes the periodic ranging between the anchor 3 and the portable device 8. This reduces the risk that the ranging communication with the dedicated device 7 will collide with the UWB signal transmitted from the portable device 8 during the periodic ranging, resulting in failure of the ranging communication with the dedicated device 7. Note that a case where the ranging communication with the dedicated device 7 fails may be understood as a case where a ranging signal from the dedicated device 7 cannot be received, i.e., a ranging value cannot be obtained.

[0128] <Supplementary Information> The above describes an aspect in which the vehicle key system 1 executes distance measurement communication with the dedicated device 7 in response to a user action on the vehicle hybrid vehicle. The user action may correspond to a change in the state of the vehicle hybrid vehicle. A change in the state of the vehicle hybrid vehicle may be, for example, opening or closing a door or stopping the vehicle from running. The vehicle key system 1 may be configured to stop periodic distance measurement communication with the portable device 8 and execute distance measurement communication with the dedicated device 7 in response to a change in the state of the vehicle hybrid vehicle. The DK-ECU 2 may be programmed to consider the distance measurement conditions to be met even when the state of the vehicle hybrid vehicle changes.

[0129] The DK-ECU 2 may be configured to retry distance measurement communication with the dedicated device 7 after a predetermined time if distance measurement communication with the dedicated device 7 fails. The DK-ECU 2 may be configured to retry distance measurement communication with the dedicated device 7 up to a maximum of X times until distance measurement communication is successful. The upper limit number of retries (X) may be set to a number such as two or three times. Completion of distance measurement communication with the dedicated device 7 may be interpreted as success of distance measurement communication or the number of attempts of distance measurement communication reaching the upper limit number. The upper limit number of retries corresponds to an example of the first number.

[0130] FIG. 7 is a flowchart corresponding to the operation of the DK-ECU 2. Step S201 in FIG. 7 corresponds to step S113 in FIG. 4. Step S202 is a step for determining whether the distance measurement communication with the dedicated device 7 performed in step S201 was successful. Distance measurement communication is successful when valid distance measurements, such as 2 m or 3 m, are obtained from two or more anchors 3 as distance measurement results. A valid distance measurement value is a value corresponding to the distance at which UWB communication is possible, and may be, for example, 20 m or less. Distance measurement communication may fail when error values ​​are output from a predetermined number or more of anchors 3, or when the number of anchors 3 from which valid distance measurements are obtained is less than a predetermined number (e.g., 2). The definition of success / failure of distance measurement communication may be designed as appropriate.

[0131] If the distance measurement communication is successful (YES in S202), the flow may be ended, and then the device position may be determined based on the distance measurement value. On the other hand, if the distance measurement communication with the dedicated device 7 fails (NO in S202), the DK-ECU 2 determines in step S203 whether the number of retries (R_Num) is less than the upper limit number of retries (X). "R_Num" in the figure represents the current number of retries executed, and its initial value may be 0. The number of retries (R_Num) may be incremented each time a retry is executed. As described above, the upper limit number of retries (X) may be a predetermined value such as 1 or 2.

[0132] If the number of retries (R_Num) is less than the upper limit number (X) (YES in S203), the DK-ECU 2 causes the anchor 3 to retry ranging communication with the dedicated device 7 in step S204. The trigger ranging retry may be performed a predetermined time after the ranging failure. The time from the failure to the retry may be specified by the number of time slots. For example, the time slot in which the retry is performed may be a time slot located Y times after the time slot in which the ranging communication failed.

[0133] The parameter Y that specifies the waiting time for retry may be set to a value obtained by adding a predetermined value (for example, 2) to the number of dedicated devices 7 registered as key devices 9 or the number of dedicated devices 7 connected to the DK-ECU 2 via LE communication. The timing for retrying trigger distance measurement is not limited to the above and may be determined according to a predetermined rule as appropriate. The timing for retrying may be notified to the dedicated devices 7 from the DK-ECU 2 via LE communication.

[0134] After step S204 is executed, the processing from step S202 onward is executed again. If the number of retries (R_Num) reaches the upper limit (X), the DK-ECU 2 may give up measuring the distance of the dedicated device 7. If the DK-ECU 2 gives up measuring the distance of the dedicated device 7, it may perform periodic distance measurement communication with the portable device 8 a predetermined number of times and then re-execute trigger distance measurement. Note that the DK-ECU 2 may perform distance measurement communication with the dedicated device 7 every time it receives a user action.

[0135] 8, the vehicle key system 1 may be configured to perform distance measurement communication with one dedicated device 7 multiple times at predetermined intervals in response to detection of a user action. Triggered distance measurement may include performing distance measurement communication multiple times with one dedicated device 7. If multiple dedicated devices 7 are connected to the DK-ECU 2, the vehicle key system 1 may perform distance measurement communication multiple times with each of the connected dedicated devices 7 as triggered distance measurement.

[0136] The example shown in Figure 8 illustrates a pattern in which ranging communication is performed intermittently three times as trigger ranging with the dedicated device 7A. Communication C41 shown in Figure 8 indicates the first ranging communication, communication C42 indicates the second ranging communication, and communication C43 indicates the third ranging communication. The number of times ranging communication with the dedicated device 7 is repeatedly performed in response to a user action is also referred to as the number of trigger ranging. The number of trigger ranging corresponds to the first number. The number of trigger ranging may be set to a value sufficiently smaller than the number of regular ranging, such as two or three times. The above embodiment corresponds to a case in which the number of trigger ranging is set to one.

[0137] The trigger ranging interval (Tq in the figure), which is the interval between executions of trigger ranging when multiple trigger ranging operations are performed, may be set to be sufficiently shorter than the regular ranging interval (e.g., less than half). For example, the trigger ranging interval may be one or two time slots. By setting the trigger ranging interval to a relatively small value, ranging communication with the dedicated device 7 is performed intensively. This allows the suspension period of regular ranging communication with the portable device 8 to be shortened.

[0138] In a configuration in which triggered ranging includes performing ranging communications multiple times, even if one of the multiple ranging communications fails, the position of the dedicated device 7 can be determined from the results of the remaining ranging communications. Performing ranging communications multiple times as triggered ranging reduces the risk of the position of the dedicated device 7 becoming unknown due to an accidental failure of ranging communications. Furthermore, by integrating (e.g., averaging) the results of multiple ranging communications performed intensively, the position of the dedicated device 7 can be determined with higher accuracy. The triggered ranging interval may be dynamically determined depending on the number of dedicated devices 7 registered in the DK-ECU 2 or the number of dedicated devices 7 connected via LE communication.

[0139] The vehicle key system 1 may be configured to perform distance measurement communication with the connected dedicated device 7 a predetermined number of times each time a user action is detected. For example, the vehicle key system 1 may perform trigger distance measurement a predetermined number of times when the driver's door handle is touched, the passenger's door handle is touched, or the start switch is pressed. As described above, the predetermined number of times may be just one, or two or more times.

[0140] <Case where the DK-ECU is connected to multiple dedicated devices> The above describes a case where only one dedicated device 7 is connected to the DK-ECU 2, but in reality, the DK-ECU 2 may be connected to multiple dedicated devices 7. Taking such a scenario into consideration, the DK-ECU 2 may pre-assign a time slot for ranging communication to each of the multiple dedicated devices 7. The pre-assigned slot number for ranging communication is also referred to as a basic slot number.

[0141] When the DK-ECU 2 is connected to multiple dedicated devices 7, it may be configured to sequentially perform trigger ranging with the multiple dedicated devices 7 at timings using pre-assigned time slots. By pre-assigning the timing (time slot) for performing trigger ranging with each dedicated device 7, communication collisions between trigger ranging operations can be prevented.

[0142] 9 is a diagram showing the operation of the DK-ECU 2 when the DK-ECU 2 is connected via LE communication to multiple portable devices 8 (8A, 8B, 8C) and multiple dedicated devices 7 (7A, 7B, 7C in the figure). For convenience, the dedicated device 7 designated by "7A" in the figure may be referred to as the first dedicated device 7A, the dedicated device 7 designated by "7B" as the second dedicated device 7B, and the dedicated device 7 designated by "7C" as the third dedicated device 7C.

[0143] Before detecting a user action (i.e., in an action waiting state), the DK-ECU 2 performs periodic distance measurement with each of the multiple portable devices 8. When the DK-ECU 2 detects a user action at time Ta, it transmits a distance measurement pause signal to the connected portable device 8 and also transmits trigger signals individually to the connected dedicated devices 7A, 7B, and 7C. The distance measurement pause signal and trigger signal may be transmitted at the nearest periodic communication opportunity determined by the connection interval.

[0144] Communication C31 in the figure represents communication in which the DK-ECU 2 transmits a trigger signal to the first dedicated device 7A. Communication C32 represents communication in which the DK-ECU 2 transmits a trigger signal to the second dedicated device 7B. Communication C33 represents communication in which the DK-ECU 2 transmits a trigger signal to the third dedicated device 7C. In conjunction with transmitting the trigger signal to the dedicated device 7, the DK-ECU 2 transmits a ranging instruction signal to the anchor 3. The ranging instruction signal may include a time slot number for ranging communication assigned to each dedicated device 7.

[0145] 9 shows, as an example, a pattern in which the communications C1 and C2 through which the DK-ECU 2 authenticates each dedicated device 7 are omitted. In other embodiments, as described above, the DK-ECU 2 may be configured to transmit a trigger signal after individually authenticating each connected dedicated device 7 in response to a user action.

[0146] Upon receiving the trigger signal, the dedicated devices 7A to 7C perform ranging communication using pre-assigned time slots. Here, the first dedicated device 7A is assigned slot number "1" (first slot). The second dedicated device 7B is assigned slot number "2" (second slot). The third dedicated device 7C is assigned slot number "3" (third slot). The slot number for each dedicated device 7 may be determined when the dedicated device 7 is registered as a key device 9 in the DK-ECU 2, in other words, at the time of pairing. For example, the slot numbers may correspond to the order in which the dedicated devices 7 are registered as key devices 9.

[0147] The trigger signal transmitted by the DK-ECU 2 to the second dedicated device 7B and the third dedicated device 7C may include information instructing the dedicated devices 7 to regard time Tb1 as the reference time so that each dedicated device 7 operates based on a common reference time. Time Tb1 is the time when the DK-ECU 2 transmits the trigger signal to the first dedicated device 7A, in other words, the time when the first dedicated device 7A receives the trigger signal. Time Tb2 in the figure represents the time when the DK-ECU 2 transmits the trigger signal to the second dedicated device 7B. Time Tb3 represents the time when the DK-ECU 2 transmits the trigger signal to the third dedicated device 7C.

[0148] The trigger signal for the second dedicated device 7B may include information indicating the difference between times Tb2 and Tb1 as correction information for the reference time. The trigger signal for the third dedicated device 7C may include information indicating the difference between times Tb3 and Tb1 as correction information for the reference time. The second dedicated device 7B and the third dedicated device 7C may determine the reference time using the correction information included in the trigger signal.

[0149] The trigger signal transmitted by the DK-ECU 2 may include the remaining time until the first slot instead of or in addition to the correction information. The dedicated device 7 may receive information for identifying the timing of ranging from the DK-ECU 2 and identify the timing of ranging based on the received information. The DK-ECU 2 may notify the DK-ECU 2 of the current slot number in the UWB time information it holds when establishing communication or at any periodic communication opportunity after establishing communication.

[0150] In this embodiment, the dedicated devices 7A, 7B, and 7C identify the times corresponding to the first, second, and third slots based on the LE signal received from the DK-ECU 2. Each of the dedicated devices 7A, 7B, and 7C then enters a UWB standby state in the time slot assigned to it and performs ranging communication. In FIG. 9 , β1 represents the ranging standby time for the first dedicated device 7A, β2 represents the ranging standby time for the second dedicated device 7B, and β3 represents the ranging standby time for the third dedicated device 7C. The DK-ECU 2 may be configured to calculate the ranging standby time for each dedicated device 7 and transmit a trigger signal specifying the ranging standby time.

[0151] The DK-ECU 2 can shorten the suspension period of regular distance measurement by intensively performing trigger distance measurement with the connected dedicated devices 7. In addition, by performing trigger distance measurement with multiple dedicated devices 7 according to pre-assigned slot numbers, it is possible to reduce the risk of overlapping trigger distance measurement timing for multiple dedicated devices 7. In other words, it is possible to reduce the risk of trigger distance measurement failure when multiple dedicated devices 7 are connected to the DK-ECU 2.

[0152] The DK-ECU 2 may dynamically determine the slot number to use for distance measurement communication depending on the number of connected dedicated devices 7. For example, if the basic slot number of the third dedicated device 7C is 3 and the third dedicated device 7C is the only dedicated device 7 connected to the DK-ECU 2, the DK-ECU 2 may use the first slot to perform distance measurement communication with the third dedicated device 7C. In other words, the time slot for distance measurement communication with the third dedicated device 7C may be moved up from the third slot to the first slot. This shortens the time required for trigger distance measurement. As a result, the responsiveness of the vehicle key system 1 to user actions may be improved.

[0153] The change in slot number may be notified to the dedicated device 7, for example, by periodic LE communication. When the combination of dedicated devices 7 connected to the DK-ECU 2 is changed, the DK-ECU 2 may update the allocation of slot numbers for ranging communication to the connected dedicated devices 7. The combination of dedicated devices 7 may be changed when an LE communication link with a previously unconnected dedicated device 7 is established, or when the connection with a previously connected dedicated device 7 is severed. The DK-ECU 2 may notify the connected dedicated device 7 of the slot number for ranging communication every time it changes the allocation of slot numbers.

[0154] It is also envisioned that with the development or application of LE communication, the DK-ECU 2 may be able to communicate with multiple dedicated devices 7 approximately simultaneously. "Almost simultaneously" may include completely simultaneous communication as well as communication with a time difference of several milliseconds. It is also envisioned that the DK-ECU 2 as a central (master) may be configured to be able to multicast data to dedicated devices 7 as peripherals (slaves).

[0155] In such a scenario, the DK-ECU 2 may detect a user action and simultaneously transmit a trigger signal to multiple connected dedicated devices 7. For example, the DK-ECU 2 may detect a user action and multicast a trigger signal to multiple connected dedicated devices 7. This configuration allows the reference times of multiple dedicated devices 7 to be set to approximately the same time even without correction information. In other words, the DK-ECU 2 does not need to calculate and transmit correction information.

[0156] <Modifications Related to Triggered Distance Measurement> In the above-described embodiment, the vehicle key system 1 is configured to perform triggered distance measurement only with the dedicated device 7 currently connected via LE to the DK-ECU 2. The vehicle key system 1 may be configured to perform triggered distance measurement sequentially with all connected key devices 9, not just the dedicated device 7. For example, the vehicle key system 1 may perform triggered distance measurement with the connected dedicated device 7, and then perform triggered distance measurement with the connected portable device 8.

[0157] According to the above aspect, even if the user carrying the portable device 8 operates a door switch while the dedicated device 7 is outside the entry area, a system response such as unlocking the vehicle Hv is quickly implemented. In other words, the responsiveness of the system can be improved.

[0158] The ranging conditions are conditions for performing trigger ranging in UWB communication, and may be referred to as trigger ranging conditions or UWB trigger ranging conditions. The UWB trigger ranging conditions may additionally include the reception strength of the LE signal from the dedicated device 7 being equal to or greater than a predetermined value. Furthermore, if the GW module 21 is configured to be able to perform CS (Channel Sounding) ranging, the UWB trigger ranging conditions may additionally include the result of CS ranging with the dedicated device 7 being less than a predetermined value. CS ranging is a method of measuring distance based on the difference in reception phase between channels, which is obtained by transmitting and receiving CW (Continuous Wave) signals over multiple channels. CS ranging is sometimes called High Accuracy Distance Measurement (HADM) or multi-channel phase difference ranging.

[0159] <Key Device Registration> The DK-ECU 2 may be configured to be able to register, delete, or disable the key device 9 based on an input signal from an input device. The DK-ECU 2 displays a key device management screen on a display based on, for example, an operation signal input from the input device. The display may be an in-vehicle display such as a center display or a meter display. The input device may be a touch panel overlaid on the in-vehicle display.

[0160] The key device management screen may include, for example, a register button, a delete button, and a list display button. The register button is a button image for registering a key device 9. The delete button is a button image for deleting a registered key device 9. The list display button is a button image for displaying a list of registered key devices 9.

[0161] When the DK-ECU 2 detects, for example, that a registration button has been selected based on the operation signal, it displays a device information input screen for inputting the type of the device to be newly registered, which is the device to be newly registered, etc. The device information input screen may include a button for inputting that the device to be newly registered is a first device type and a button for inputting that it is another communication device. The device information input screen may also include a pairing start button for starting pairing, etc. after selecting the device type.

[0162] The DK-ECU 2 acquires data indicating the type of communication device (i.e., device type) to be newly registered based on user operations on the screen. The device type data of the key device 9 acquired by the DK-ECU 2 is stored in the key data storage unit 2331 in association with the device ID, etc. When registering the key device 9 as a key device 9, a basic slot number may be assigned to the key device 9 to be registered. The basic slot number may be set to a value obtained by adding 1 or 2 to the number of registered key devices 9. The basic slot number may also be stored in association with the device ID, etc. A dedicated device 7 such as a smart key may be registered as a key device 9, for example, at a dealership.

[0163] <Device Type> In one embodiment, the first type device, which is a communication device of the first device type, may be the dedicated device 7 as a key for the vehicle Hv, as described above. The second type device, which is a communication device of the second device type, may be a communication device used for various purposes, such as a smartphone.

[0164] In one aspect, the first type device may be a communication device on which a user cannot install any application, and the second type device may be a communication device on which a user can install any application. The first and second device types may be distinguished by whether or not a user can install an application. In another aspect, the first type device may be a communication device that does not have a communication module for accessing the Internet, and the second type device may be a communication device that has a communication module for accessing the Internet. The communication module for accessing the Internet is, for example, a communication module configured to perform Wi-Fi (registered trademark) or cellular communication. The first and second device types may be distinguished by whether or not the device can access the Internet.

[0165] In another aspect, the first type device may be a communication device whose battery capacity is equal to or less than a predetermined threshold, and the second type device may be a communication device whose battery capacity is equal to or greater than the threshold. The first and second device types may be distinguished by battery capacity. The threshold may be set to a value equivalent to a coin battery, such as 225 mAh or 610 mAh. In yet another aspect, the first type device may be a communication device powered by a primary battery, and the second type device may be a communication device powered by a secondary battery. The first and second device types may be distinguished by whether or not the device is rechargeable.

[0166] Alternatively, the first-type device may be a communication device registered in the DK-ECU2 at the vehicle hybrid factory or dealership, and the second-type device may be a communication device registered in the DK-ECU2 by the user after delivery of the vehicle hybrid. The device type may be static or may change depending on the state of the communication device. For example, a communication device whose remaining battery power is less than a predetermined threshold may be a first-type device, and a communication device whose remaining battery power is equal to or greater than the predetermined threshold may be a second-type device. The DK-ECU2 may obtain the remaining battery power of the connected device via LE communication and determine the device type.

[0167] The device type may be freely and selectively registered by the user. For example, a smartphone may be registered as a first-type device. By registering a smartphone as a first-type device, the user can reduce the power consumption for ranging communication in the smartphone. On the other hand, by registering a smartphone as a second-type device, the user can improve system responsiveness when a user action is performed based on the ranging results before the user action.

[0168] <Modification of Communication Protocol> Bluetooth LE is the first communication protocol (first communication method), and UWB-IR is the second communication protocol (second communication method). UWB-IR may also be referred to as IR-UWB. The communication method (in other words, the first wireless protocol) between the GW module 21 and the key device 9 is not limited to Bluetooth LE, but may be Bluetooth Classic, Wi-Fi, EnOcean (registered trademark), Zigbee (registered trademark), or the like. Ranging communication is not limited to UWB-IR, but may be performed using Bluetooth LE, Wi-Fi, or the like. For example, the ranging method using Bluetooth LE may be CS ranging. Each anchor 3 may be configured to be able to perform CS ranging. In this disclosure, the terms communication protocol, communication standard, and communication method may be interchangeable.

[0169] <Application Examples of the Present Disclosure> The present disclosure is applicable not only to vehicles but also to electronic key systems for buildings and facilities. For example, the present disclosure is applicable to a system that controls the locking state of building doors. The key device 9 may be a wireless key for a building door, or a wireless key for a door such as a locker or safe. The target object is not limited to a vehicle, and may be various objects such as a building, a safe, a locker, or a delivery box.

[0170] <Supplementary Remark (1)> The present disclosure also includes the following technical ideas and configurations. The present disclosure also includes a position determination system, a computer program, a position determination method, and a recording medium on which the computer program is recorded, which correspond to the following technical ideas.

[0171] [Technical Idea 1] A position determination device for determining the position of a key device relative to an object, comprising: a storage unit (2331) storing information on a communication device registered as the key device; and a control unit (23) executing a process for determining the position of the key device using a plurality of communication units configured to be able to perform wireless communication with the key device, wherein the plurality of communication units include a first communication unit (21) configured to be able to perform data communication with the key device according to a predetermined first communication protocol, and a second communication unit (3) configured to be able to perform ranging communication with the key device according to a predetermined second communication protocol, wherein the storage unit is configured to be able to register both a first type device (7) that is a communication device of a first device type and a second type device (8) that is a communication device of a second device type as the key device, and wherein the control unit transmits a signal to the second communication unit instructing the second communication unit to perform the ranging communication with the second type device based on the first communication unit having established a communication connection with the second type device; A location determination device configured to perform the following: when the first communication unit is connected to the first type device for communication and a predetermined distance measurement condition is met, sending a signal to the second communication unit instructing the second communication unit to perform the distance measurement communication with the first type device; and obtaining a result of the distance measurement communication from the second communication unit and determining the location of the key device that performed the distance measurement communication with the second communication unit.

[0172] The control unit included in the position determination device may be configured such that, when the first communication unit establishes a communication connection with the first type device, the control unit does not send an instruction to the second communication unit to execute distance measurement communication with the first type device until a distance measurement condition is met. When the first communication unit establishes a communication connection with the first type device, the control unit may suspend distance measurement communication with the first type device until the distance measurement condition is met, and promptly (within a predetermined time) send an instruction to the second communication unit to execute distance measurement communication with the first type device after the distance measurement condition is met. The predetermined time may be set in consideration of the system's response speed to user actions, such as 200 milliseconds or 300 milliseconds. Furthermore, when the first communication unit establishes a communication connection with the second type device, the control unit may send an instruction to the second communication unit to execute distance measurement communication with the second type device within the predetermined time. The instruction to execute distance measurement communication with the second type device may be a signal instructing the start of periodic distance measurement communication with the second type device. The control unit may be configured to change the timing of transmitting an instruction to perform ranging communication to the second communication unit depending on the device type of the key device that is communicatively connected to the first communication unit.

[0173] [Technical Idea 2] The control unit is configured to: when the first communication unit has established a communication connection with the second type device, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the second type device up to a predetermined second number of times; when the first communication unit has established a communication connection with the first type device and the ranging condition is met, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the first type device up to a predetermined first number of times; and the first number of times is set to be less than the second number of times, in the position determination device described in Technical Idea 1.

[0174] In the above configuration, the execution interval of ranging communication with the first type device may be set to half or less of the execution interval of ranging communication with the second type device, and the execution interval of ranging communication with the first type device may be set to 60 milliseconds or less, while the execution interval of ranging communication with the second type device may be set to 120 milliseconds or more.

[0175] [Technical Idea 3] The control unit of the position determination device described in Technical Idea 1 is configured to: when the first communication unit has established a communication connection with the second type device, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the second type device up to a predetermined number of times; and when the first communication unit has established a communication connection with the first type device and the ranging condition is met, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to execute the ranging communication with the first type device once.

[0176] [Technical Idea 4] The control unit is configured to be able to detect a user action with respect to the object based on an output signal from an action sensor, and the position determination device described in any one of Technical Ideas 1 to 3 includes a case where the user action is detected when the distance measurement condition is met.

[0177] [Technical Idea 5] The control unit is configured to: when the first communication unit has established a communication connection with the second type device, cause the second communication unit to repeatedly execute the ranging communication with the second type device up to a predetermined number of times by sending a predetermined instruction signal to the second communication unit; and when the first communication unit has established a communication connection with the first type device and the ranging condition is met while the second communication unit is performing periodic ranging communication with the second type device, temporarily suspend the periodic ranging communication between the second communication unit and the second type device until a predetermined resumption condition is met, in a position determination device described in any one of Technical Ideas 1 to 4.

[0178] [Technical Idea 6] The position determination device described in Technical Idea 5, wherein the resumption condition includes the end of the ranging communication between the second communication unit and the first type device, and the control unit is configured to, upon the resumption condition being met, send a predetermined resumption instruction to the second communication unit and cause the second communication unit to resume the periodic ranging communication with the second type device.

[0179] [Technical Idea 7] A position determination device described in any one of Technical Ideas 1 to 6, wherein the timing for performing the ranging communication is determined using time slots that divide time into certain time widths, and the control unit is configured to: notify the second communication unit of information about the time slot for ranging communication with the first type device based on the first communication unit having established a communication connection with the first type device, and cause the second communication unit to perform the ranging communication with the first type device in the notified time slot.

[0180] [Technical Idea 8] A position determination device described in any one of Technical Ideas 1 to 7, wherein the timing for performing the ranging communication is determined using time slots that divide time into certain time widths, the memory unit stores data indicating the number of the time slot for the first type device, and the control unit is configured to: acquire the number of the time slot for the first type device that is communicatively connected to the first communication unit by referring to the memory unit; notify the second communication unit of the acquired time slot number; and cause the second communication unit to perform the ranging communication with the first type device in the notified time slot.

[0181] [Technical Idea 9] The control unit transmits a predetermined trigger signal using the first communication unit toward the first type device to which the first communication unit is connected, and the timing at which the second communication unit performs the ranging communication with the first type device is determined based on the transmission time of the trigger signal and the number of the time slot for the first type device, in the position determination device described in Technical Idea 8.

[0182] [Technical Idea 10] A position determination device described in any one of Technical Ideas 1 to 9, wherein the timing for performing the ranging communication is determined using time slots that divide time into certain time widths, and the control unit is configured to: determine the number of the time slot for the first type device depending on the number of first type devices that are communicatively connected to the first communication unit; and cause the second communication unit to perform the ranging communication with the first type device in the determined time slot.

[0183] [Technical Idea 11] The control unit is configured to be able to detect a user action on the object based on an output signal from an action sensor, and when the first communication unit is communicatively connected to the first type device and when the user action is detected, to cause the first communication unit to execute communication to authenticate the first type device, and if the authentication of the first type device is successful, to send a signal to the second communication unit instructing it to execute the ranging communication with the first type device, and if the authentication of the first type device is not successful, to not send a signal to the second communication unit instructing it to execute the ranging communication with the first type device. A position determination device described in any one of Technical Ideas 1 to 10.

[0184] [Technical Idea 12] A position determination device described in any one of Technical Ideas 1 to 11, wherein the first type device is a communication device whose battery capacity is less than a predetermined threshold, and the second type device is a communication device whose battery capacity is equal to or greater than the threshold.

[0185] [Technical Concept 13] The position determination device according to any one of Technical Concepts 1 to 12, wherein the first communication protocol is Bluetooth (registered trademark) Low Energy, and the second communication protocol is Ultra Wide Band - Impulse Radio.

[0186] <Supplementary Note (2)> The various flowcharts shown in this disclosure are all examples, and the number of steps constituting the flowcharts and the execution order of the processes can be changed as appropriate. The controls shown in each flowchart may be combined / executed in parallel to the extent that there is no contradiction. Expressions such as acquisition, determination, detection, generation, and calculation may be interchangeable. When a device acquires certain data, it also includes the device generating the data based on a signal input from another device / sensor.

[0187] The apparatus, system, and methods described herein may be implemented by a special-purpose computer comprising a processor programmed to execute one or more functions embodied in a computer program. The apparatus and methods described herein may be implemented using dedicated hardware logic circuits. The apparatus and methods described herein may 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. The processor may be any computing core, such as a CPU, MPU, GPU, or DFP (Data Flow Processor). Some or all of the functions of the DK-ECU may be implemented as hardware. Some or all of the functions of the DK-ECU may be implemented using a system-on-chip (SoC), an integrated circuit (IC), or a field-programmable gate array (FPGA).

[0188] The computer program includes instructions that are executed by a computer. The computer program may be stored in a computer-readable non-transitory tangible storage medium. The storage medium for the computer program may be a variety of media, such as a hard-disk drive (HDD), a solid-state drive (SSD), or a flash memory.

Claims

1. A position determination device for determining the position of a key device relative to an object, comprising: a memory unit (2331) storing information on a communication device registered as the key device; and a control unit (23) executing a process for determining the position of the key device using a plurality of communication units configured to be able to perform wireless communication with the key device, wherein the plurality of communication units include a first communication unit (21) configured to be able to perform data communication with the key device according to a predetermined first communication protocol, and a second communication unit (3) configured to be able to perform ranging communication with the key device according to a predetermined second communication protocol, wherein the memory unit is configured to be able to register both a first type device (7) that is a communication device of a first device type and a second type device (8) that is a communication device of a second device type as the key device, and wherein the control unit transmits a signal to the second communication unit instructing it to perform the ranging communication with the second type device based on the first communication unit having established a communication connection with the second type device; A location determination device configured to perform the following: when the first communication unit is connected to the first type device for communication and a predetermined distance measurement condition is met, sending a signal to the second communication unit instructing the second communication unit to perform the distance measurement communication with the first type device; and obtaining a result of the distance measurement communication from the second communication unit and determining the location of the key device that performed the distance measurement communication with the second communication unit.

2. The control unit is configured to: when the first communication unit has established a communication connection with the second type device, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the second type device up to a predetermined second number of times; when the first communication unit has established a communication connection with the first type device and the ranging condition is met, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the first type device up to a predetermined first number of times; and the first number of times is set to be less than the second number of times. A position determination device as described in claim 1.

3. The position determination device described in claim 1, wherein the control unit is configured to: when the first communication unit has established a communication connection with the second type device, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the second type device up to a maximum of a predetermined number of times; and when the first communication unit has established a communication connection with the first type device and the ranging condition is met, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to execute the ranging communication with the first type device once.

4. The position determination device according to claim 1, wherein the control unit is configured to be able to detect a user action relative to the object based on an output signal from an action sensor, and the case where the distance measurement condition is met includes the case where the user action is detected.

5. The position determination device described in claim 1, wherein the control unit is configured to: when the first communication unit has established a communication connection with the second type device, send a predetermined instruction signal to the second communication unit, thereby causing the second communication unit to repeatedly execute the ranging communication with the second type device up to a predetermined number of times; and when the first communication unit has established a communication connection with the first type device and the ranging condition is met while the second communication unit is performing periodic ranging communication with the second type device, temporarily suspend the periodic ranging communication between the second communication unit and the second type device until a predetermined resumption condition is met.

6. The position determination device described in claim 5, wherein the resumption condition includes the end of the ranging communication between the second communication unit and the first type device, and the control unit is configured to, upon the resumption condition being met, send a predetermined resumption instruction to the second communication unit and cause the second communication unit to resume the periodic ranging communication with the second type device.

7. The position determination device described in claim 1, wherein the timing for performing the ranging communication is determined using time slots that divide time into fixed time intervals, and the control unit is configured to notify the second communication unit of information about the time slot for ranging communication with the first type device based on the first communication unit having established a communication connection with the first type device, and to cause the second communication unit to perform the ranging communication with the first type device in the notified time slot.

8. A position determination device as described in claim 1, wherein the timing for performing the ranging communication is determined using time slots that divide time into fixed time intervals, the memory unit stores data indicating the number of the time slot for the first type device, and the control unit is configured to: obtain the number of the time slot for the first type device that is communicatively connected to the first communication unit by referring to the memory unit; notify the second communication unit of the obtained time slot number; and cause the second communication unit to perform the ranging communication with the first type device in the notified time slot.

9. The position determination device described in claim 8, wherein the control unit uses the first communication unit to transmit a predetermined trigger signal toward the first type device to which the first communication unit is connected, and the timing at which the second communication unit performs the ranging communication with the first type device is determined based on the transmission time of the trigger signal and the number of the time slot for the first type device.

10. A position determination device as described in claim 1, wherein the timing for performing the ranging communication is determined using time slots that divide time into fixed time intervals, and the control unit is configured to determine the number of the time slot for the first type device depending on the number of first type devices that are communicatively connected to the first communication unit, and to cause the second communication unit to perform the ranging communication with the first type device in the determined time slot.

11. The control unit is configured to be able to detect a user action on the object based on an output signal of an action sensor, and when the first communication unit is communicatively connected to the first type device and when the user action is detected, to cause the first communication unit to execute communication to authenticate the first type device, and if authentication of the first type device is successful, to send a signal to the second communication unit instructing it to execute the ranging communication with the first type device, and if authentication of the first type device is not successful, to not send a signal to the second communication unit instructing it to execute the ranging communication with the first type device. A position determination device as described in claim 1.

12. The position determination device according to claim 1, wherein the first type device is a communication device having a battery capacity less than a predetermined threshold, and the second type device is a communication device having a battery capacity equal to or greater than the threshold.

13. The position determining device of claim 1, wherein the first communication protocol is Bluetooth (registered trademark) Low Energy, and the second communication protocol is Ultra Wide Band - Impulse Radio.

14. A position determination system for determining the position of a key device relative to an object, comprising: a memory unit (2331) storing information on a communication device registered as the key device; a first communication unit (21) configured to be able to perform data communication with the key device according to a predetermined first communication protocol; a second communication unit (3) configured to be able to perform distance measurement communication with the key device according to a predetermined second communication protocol; and a control unit (23) executing a process for determining the position of the key device connected to the first communication unit using the second communication unit, wherein the memory unit is configured to be able to register both a first type device (7) that is a communication device of a first device type and a second type device (8) that is a communication device of a second device type as the key device, and the control unit transmits an instruction to the second communication unit to perform distance measurement communication with the second type device based on the first communication unit having connected to the second type device for communication; A location determination system configured to: send an instruction to the second communication unit to perform ranging communication with the first type device when the first communication unit is connected to the first type device for communication and a predetermined ranging condition is satisfied; and obtain a result of the ranging communication from the second communication unit and determine the location of the key device that performed the ranging communication with the second communication unit.

15. A location determination method executed by a computer for determining the location of a communication device registered as a key device, comprising: communicating with a first communication unit (21) configured to be able to perform data communication with the key device according to a predetermined first communication protocol, and acquiring data of a connected device that is the key device connected to and communicating with the first communication unit; communicating with a second communication unit (3) configured to be able to perform distance measurement communication with the key device according to a predetermined second communication protocol; accessing a storage unit that stores information about the communication device registered as the key device, and identifying the device type of the connected device; and when the first communication unit has connected to and communicating with a first type device (7) that is a communication device of a first device type, subsequently transmitting a signal to the second communication unit to instruct the second communication unit to perform distance measurement communication with the first type device based on the establishment of a predetermined distance measurement condition. A location determination method including: when the first communication unit is connected to a second type device (8) that is a communication device of a second device type, transmitting a signal to the second communication unit instructing the second communication unit to perform the ranging communication with the second type device even if the ranging condition is not met; and obtaining a result of the ranging communication from the second communication unit and determining the location of the key device that performed the ranging communication with the second communication unit.

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