Onboard system, onboard apparatus, and method

Abstract

An onboard system (1) is provided with an anchor (3) configured so as to be capable of performing ranging communication using UWB pulses to communicate with a mobile device (9). The anchor (3) comprises, as operational states, a standby state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received. The transition timing, that is the timing at which the anchor (3) enters the standby state, or the duration of the standby state is determined on the basis of communication setting data whereby the scheduled transmission time that is the time at which the UWB pulses are to be transmitted can be identified, device oscillator error information, and anchor oscillator error information.

Description

In-vehicle system, in-vehicle device and method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-198577 filed in Japan on November 22, 2023, and the contents of the original application are incorporated by reference in their entirety.

[0002] TECHNICAL FIELD The disclosure herein relates to in-vehicle systems, in-vehicle devices and methods.

[0003] Patent Document 1 discloses a configuration in which a portable device and an in-vehicle device are connected for communication via Bluetooth Low Energy (Bluetooth is a registered trademark) and then perform UWB (Ultra Wide Band) communication between the portable device and the in-vehicle device. The in-vehicle device disclosed in Patent Document 1 determines the location of the portable device based on the results of the UWB communication. The contents of the prior art documents are incorporated by reference as explanations of the technical elements in this specification.

[0004] Special table 2019-528387 publication

[0005] In ranging communication using UWB communication, the receiving device must be in a state where it can receive the pulse signal when it is transmitted (hereinafter referred to as a reception standby state). Therefore, the receiving device is configured to identify the scheduled transmission time by communicating with the transmitting device in advance and to enter a reception standby state at the scheduled transmission time. However, the developers of the present disclosure have further investigated the above configuration and discovered that ranging communication may fail due to a time difference caused by clock errors between devices.

[0006] One disclosed object is to provide an in-vehicle system that can suppress failure to receive signals in ranging communications.

[0007] The in-vehicle system disclosed herein is an in-vehicle system configured to be able to perform ranging communication with a portable device using UWB pulses, and includes a control device configured to be able to wirelessly communicate with the portable device, and an anchor configured to be able to communicate with the control device and to perform ranging communication with the portable device. The control device acquires, by communicating with the portable device, a reference time, which is a time used as a reference for performing ranging communication, and device oscillator error information, which is information regarding the error of a device oscillator, which is an oscillator possessed by the portable device; acquires communication setting data, which is determined based on the reference time information and is capable of specifying a scheduled transmission time, which is the time when the portable device will transmit UWB pulses; and transmits the communication setting data to the anchor. The anchor has, as its operating states, a standby state in which it is able to receive UWB pulses, and a stopped state in which it is unable to receive UWB pulses. The anchor has an anchor oscillator, which is an oscillator, and is equipped with a function of measuring time based on an output signal of the anchor oscillator. The anchor acquires anchor oscillator error information, which is error information of the anchor oscillator. The transition timing, which is the timing when the anchor enters the standby state, or the duration of the standby state is determined based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

[0008] The disclosed in-vehicle system determines the timing to transition to a standby state based on the communication setting data, the portable device oscillator error information, and the anchor oscillator error information. This reduces the influence of time lag caused by clock errors between the portable device oscillator and the anchor oscillator. In other words, this configuration reduces failures of signal reception during ranging communication.

[0009] The vehicle-mounted device disclosed herein is equipped with a first communication unit for performing ranging communication with a portable device using UWB pulses, and a second communication unit for communicating with a control device, and has operating states including a standby state in which UWB pulses can be received, and a stopped state in which UWB pulses cannot be received.The vehicle-mounted device has an anchor oscillator, which is an oscillator, and is equipped with a function for measuring time based on the output signal of the anchor oscillator.It acquires anchor oscillator error information, which is error information of the anchor oscillator, and acquires communication setting data from the control device that can identify the scheduled transmission time, which is the time at which the portable device will transmit UWB pulses, and is determined based on device oscillator error information, which is information regarding the error of the device oscillator, which is an oscillator possessed by the portable device, and a reference time, which is the time used as a reference for performing ranging communication.The vehicle-mounted device determines the transition timing, which is the timing to enter standby mode, or the duration of the standby mode, based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

[0010] The disclosed in-vehicle device determines the timing to transition to a standby state based on the communication setting data, the portable device oscillator error information, and the anchor oscillator error information. This reduces the influence of time lag caused by clock errors between the portable device oscillator and the anchor oscillator. In other words, this configuration reduces failures of signal reception during ranging communication.

[0011] The method disclosed herein is a method executed by an in-vehicle system that performs ranging communication with a portable device using UWB pulses, the in-vehicle system including a control device and an anchor that has, as operating states, a standby state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received, and includes the control device acquiring a reference time and device oscillator error information, which is information regarding the error of a device oscillator, which is an oscillator possessed by the portable device, by communicating with the portable device, the control device generating communication setting data based on the reference time information, the control device transmitting the communication setting data to the anchor, acquiring anchor oscillator error information, which is error information of an anchor oscillator, which is an oscillator possessed by the anchor, and determining the transition timing, which is the timing at which the anchor enters a standby state, or the duration of the standby state, based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

[0012] According to the disclosed method, the timing to transition to the standby state or timings are determined based on the communication setting data, the portable device oscillator error information, and the anchor oscillator error information. This makes it possible to suppress the influence of time lag caused by clock errors between the portable device oscillator and the anchor oscillator. In other words, this configuration makes it possible to suppress failures of signal reception in ranging communications.

[0013] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings.

[0014] FIG. 1 is a diagram showing an example of a schematic configuration of an in-vehicle system. FIG. 2 is a diagram showing an example of a schematic configuration of a portable device. FIG. 3 is a diagram showing a schematic configuration of an in-vehicle system. FIG. 4 is a diagram showing a schematic configuration of a UWB anchor. FIG. 5 is a diagram showing an example of an arrangement of UWB anchors. FIG. 6 is a diagram showing a schematic configuration of a control unit. FIG. 7 is a diagram showing a flow of ranging communication. FIG. 8 is a diagram showing an overview of a ranging sequence. FIG. 9 is a diagram showing details of a ranging sequence. FIG. 10 is a diagram showing problems caused by errors in an oscillator. FIG. 11 is a diagram showing how to address problems caused by errors in an oscillator. FIG. 12 is a sequence diagram showing the operation of a vehicle from communication connection to the end of a ranging sequence. FIG. 13 is a diagram showing an overview of recorrection. FIG. 14 is a diagram showing a ranging sequence of a third modified example.

[0015] Hereinafter, an embodiment and several modified examples will be described with reference to the drawings. Note that in the embodiment and each modified example, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in the embodiment and each modified example, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of the embodiment and each modified example, configurations of the embodiment and each modified example may be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0016] In the following description, components having the same function may be given the same reference numerals, and a detailed description thereof may be omitted. Also, components having the same function may be given the same or similar names, and a detailed description thereof may be omitted. When only a part of the configuration is mentioned, the description given elsewhere may apply to the other parts.

[0017] As an example of an embodiment of an in-vehicle system according to the present disclosure, a vehicle electronic key system to which the in-vehicle system is applied will be described below with reference to Fig. 1. As shown in Fig. 1, the vehicle electronic key system according to the present disclosure includes an in-vehicle system 1 mounted on a vehicle Hv and a portable device 9, which is a communication terminal carried by the user of the vehicle Hv.

[0018] <Overall Overview> The in-vehicle system 1 and the portable device 9 are configured to be able to perform UWB (Ultra Wide Band) wireless communication (hereinafter, UWB communication). That is, the in-vehicle system 1 and the portable device 9 are configured to be able to transmit and receive pulsed radio waves (hereinafter, UWB pulses) used in UWB communication. The UWB pulse used in UWB communication may be a signal having an extremely short pulse width (e.g., 2 nanoseconds) and a bandwidth of 500 MHz or more (i.e., ultra-wide bandwidth). Hereinafter, a wireless signal using a UWB pulse 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. Alternatively, the UWB signal may be a pulse sequence signal including multiple UWB pulses. The UWB signal may include data indicating the sender.

[0019] Frequency bands available for UWB communication (hereinafter referred to as UWB bands) include 3.2 GHz to 10.6 GHz, 3.4 GHz to 4.8 GHz, 7.25 GHz to 10.6 GHz, and 22 GHz to 29 GHz. Of these various frequency bands, the UWB pulses in this embodiment are realized using radio waves in the 3.2 GHz to 10.6 GHz band. The frequency band used for the UWB pulses may be selected appropriately depending on the country in which the vehicle hybrid vehicle is used. The bandwidth of the UWB pulses may be 500 MHz or greater, and may be 1.5 GHz or greater.

[0020] Various modulation methods can be used for UWB communication, such as pulse position modulation (PPM), which modulates the pulse generation position. Specifically, modulation methods may include on-off keying (OOK), pulse width modulation (PWM), pulse-amplitude modulation (PAM), or pulse-code modulation (PCM). On-off modulation is a method of representing information (e.g., 0 and 1) by the presence or absence of a UWB pulse. Pulse width modulation is a method of representing information by pulse width. Pulse amplitude modulation is a method of representing information by the amplitude of a UWB pulse. Pulse code modulation is a method of representing information by a combination of pulses.

[0021] Furthermore, the in-vehicle system 1 and the portable device 9 of this embodiment are configured to be able to implement short-range wireless communication (hereinafter, SRWC) as a second communication method. The first communication method refers to the aforementioned UWB communication. The first communication method and the second communication method are different communication methods. The second communication method is, for example, wireless communication conforming to the Bluetooth (registered trademark) Low Energy standard. The SRWC protocol may be a method other than Bluetooth Low Energy, such as Wi-Fi (registered trademark) or ZigBee (registered trademark). The SRWC as the second communication method may be capable of providing a communication distance of, for example, several meters to several tens of meters. Hereinafter, in order to distinguish between UWB pulses in UWB communication and SRWC radio signals, SRWC signals will also be referred to as SRWC signals. Specific configurations of the in-vehicle system 1 and the portable device 9 will be described in order below.

[0022] <Configuration of Portable Device 9> First, the configuration and operation of the portable device 9 will be described. The portable device 9 is associated with the in-vehicle system 1 and functions as an electronic key for the vehicle Hv. The portable device 9 may be a general-purpose communication terminal used for various purposes. For example, the portable device 9 is a smartphone. The portable device 9 may also be an information processing terminal such as a tablet terminal. The portable device 9 may also be a small rectangular, oval, fob, or card-type device known as a smart key. Alternatively, the portable device 9 may be configured as a wearable device worn on the user's finger, arm, or the like.

[0023] 2, the portable device 9 includes an SRWC antenna 91, a high-frequency circuit 92, a device control unit 93, a UWB antenna 94, a transmitting circuit 95, a receiving circuit 96, a UWB control unit 97, a device oscillator 98, and a temperature sensor 99. The device control unit 93 is connected to the UWB control unit 97 and the high-frequency circuit 92 so as to be able to communicate with each other.

[0024] The device control unit 93 is configured to control the operations of the high frequency circuit 92 and the UWB control unit 97. The device control unit 93 includes a CPU (Central Processing Unit), memory, a ROM (Read Only Memory), and a communication IF (Interface). The UWB control unit 97 has a function of measuring time based on the output signal of the device oscillator 98.

[0025] The SRWC antenna 91 and the high-frequency circuit 92 are components for implementing SRWC. The high-frequency circuit 92 is a circuit that performs predetermined signal processing such as digital-to-analog conversion, frequency conversion, modulation, etc. The high-frequency circuit 92 provides the SRWC signal transmitted from the vehicle hybrid vehicle and received by the SRWC antenna 91 to the device control unit 93. The high-frequency circuit 92 also modulates data input from the device control unit 93 and wirelessly transmits the modulated data from the SRWC antenna 91 to the vehicle hybrid vehicle.

[0026] The UWB control unit 97 is configured to control the operations of the transmission circuit 95 and the reception circuit 96. The UWB control unit 97 may include a CPU, a memory, a ROM, and a communication IF.

[0027] The UWB antenna 94, transmission circuit 95, and reception circuit 96 are configured to transmit and receive UWB pulses. The transmission circuit 95 generates a modulated signal by electrically processing, for example modulating, a baseband signal input from the UWB control unit 97, and transmits this modulated signal via the UWB antenna 94. When the reception circuit 96 receives from the UWB antenna 94 a series of modulated signals (i.e., pulse sequence signals) including a plurality of UWB pulses transmitted from the in-vehicle system 1, it demodulates the received signal and restores the data before modulation. The reception circuit 96 then outputs the restored data to the UWB control unit 97.

[0028] The device oscillator 98 is electrically connected to each of the transmitting circuit 95, the receiving circuit 96, and the UWB control unit 97. The device oscillator 98 functions as a clock signal source. The output signal of the device oscillator 98 is used for time measurement in the UWB control unit 97. For example, the UWB control unit 97 counts the clock signal generated by the device oscillator 98 to measure the elapsed time from a reference time / ranging start time (described later). The device oscillator 98 may be a ceramic oscillator or a crystal oscillation circuit including a crystal oscillator. The device oscillator 98 may be a VCO (Voltage Controlled Oscillator) that uses a crystal oscillator as a resonator, i.e., a VCXO (Voltage Controlled Xtal Oscillator).

[0029] The UWB control unit 97 controls the UWB antenna 94 to transmit UWB pulses at a specified timing in a ranging sequence, which will be described later. The UWB control unit 97 measures the specified timing based on the output signal of the device oscillator 98.

[0030] The temperature sensor 99 is a sensor for measuring the temperature of the device oscillator 98. The temperature sensor 99 may measure the temperature around the device oscillator 98, or may measure the temperature of the portable device 9. The device control unit 93 acquires device temperature information, which is information relating to the temperature of the device oscillator 98 measured by the temperature sensor 99. The temperature of the device oscillator 98 is not limited to the temperature of the device oscillator 98 itself, but may be the temperature of a predetermined part of the portable device 9, such as the temperature around the device oscillator 98.

[0031] The device control unit 93 stores device characteristic data in its own ROM, which is data for identifying the error of the device oscillator 98 caused by temperature. The error of the device oscillator 98 is, for example, an error in the frequency of the device oscillator 98. The frequency error of the device oscillator 98 is, for example, the difference between the nominal frequency and the actual frequency of the device oscillator 98. The device characteristic data may be a table or map showing the amount of error according to temperature. The device characteristic data may also be a function / program that takes temperature as input and the amount of error as output. The device control unit 93 identifies the value of the frequency error of the device oscillator 98 based on the acquired device temperature information and the device oscillator device characteristic data.

[0032] Due to the influence of temperature, an oscillator may oscillate at a frequency different from the nominal frequency. If an error occurs in the oscillator frequency, an error will occur in the time measured based on the clock signal generated by the oscillator. Here, we will consider the impact of an error occurring in the device oscillator 98. In this case, in the ranging sequence, the device control unit 93 controls the UWB antenna 94 to transmit UWB pulses at a specified timing, but an error occurs in the measured time. This causes a discrepancy between the expected specified timing and the actual timing of transmitting the UWB pulses.

[0033] In this embodiment, in order to reduce the influence of the error of the device oscillator 98, the device control unit 93 generates device oscillator error information, which is information relating to the error of the device oscillator 98. The device oscillator error information is information that directly or indirectly indicates the error of the device oscillator 98. In this embodiment, the device oscillator error information is a specific value of the error of the device oscillator 98 that the device control unit 93 obtains by calculation based on the device temperature information. The device control unit 93 transmits the device oscillator error information to the vehicle Hv via the SRWC.

[0034] <Configuration of In-Vehicle System 1> Next, the functions and configuration of the in-vehicle system 1 will be described with reference to Fig. 3. The in-vehicle system 1 includes a distance measurement ECU 2, an anchor 3, and a body ECU 4. The body ECU 4 is an ECU (Electronic Control Unit) that switches the locking mechanisms of the doors of the vehicle Hv from an unlocked state to a locked state, or vice versa, based on a request from the distance measurement ECU 2 or a user.

[0035] The ranging ECU 2 is an ECU that executes the ranging sequence. The ranging sequence is a series of processes that includes repeatedly executing multiple ranging communications a predetermined number of times. The ranging communications are communications that measure the distance between the portable device 9 and the vehicle Hv. Details of the ranging sequence and ranging communications will be described later. Because the ranging sequence includes multiple ranging communications, executing the ranging sequence corresponds to performing ranging communications. The ranging ECU 2 is configured to start the ranging sequence at a timing determined based on a reference time. In other words, the ranging ECU 2 is configured to intermittently execute ranging communications multiple times after the reference time at timings determined based on the reference time. The ranging ECU 2 may notify the body ECU 4 of the results of the ranging communications or send a request to the body ECU 4 according to the results of the ranging communications. With each ranging communication, the ranging ECU 2 may obtain the ranging results from the anchor 3 and determine the position of the portable device 9 relative to the vehicle Hv. The distance measurement ECU 2 includes an SRWC antenna 21, a high-frequency circuit 22, an in-vehicle communication unit 23, and a control unit 24. The in-vehicle communication unit 23 is configured to enable the control unit 24 to communicate with other in-vehicle devices such as the anchor 3 and the body ECU 4.

[0036] The control unit 24 is a module that controls the operation of the distance measurement ECU 2 and is configured to execute control for performing distance measurement processing. As shown in FIG. 6 , the control unit 24 includes a processor 241, a memory 242, a storage 243, and a communication IF 244. The processor 241 is, for example, a CPU. The memory 242 is a volatile storage medium. The storage 243 is configured to include a non-volatile storage medium such as a flash memory. The communication IF 244 is a circuit module that functions as an interface for the processor 241 to communicate with other devices. The communication IF 244 is realized using analog circuit elements, ICs, etc. Hereinafter, the descriptions of the control unit 24, the processor 241, and the distance measurement ECU 2 may be interpreted interchangeably as appropriate.

[0037] The control unit 24 performs SRWC with the portable device 9 prior to the ranging sequence. Based on the establishment of a communication link between the portable device 9 and the SRWC, the control unit 24 transmits a request signal to the portable device 9 requesting the start of the ranging sequence. The control unit 24 then receives a response signal from the portable device 9 as a reply to the request signal. The response signal includes data specifying a reference time, which is the time used as a reference for performing the ranging sequence, device oscillator error information, and communication setting data. The data specifying the reference time is data for setting or sharing the reference time between the portable device 9 and the control unit 24. The data specifying the reference time may be a code instructing the portable device 9 to regard the time of reception of the signal as the reference time.

[0038] The control unit 24 uses the time when the SRWC signal transmitted from the portable device 9 is received as the reference time. The time when the SRWC signal is received may be the time when the SRWC antenna 91 receives the signal, or the time when the high-frequency circuit 92 performs predetermined signal processing.

[0039] The communication setting data is information that can identify the scheduled transmission time, which is the time when the portable device 9 transmits a UWB pulse in the ranging sequence, and is determined based on information about a reference time. The scheduled transmission time corresponds to the time when the portable device 9 is likely to transmit a UWB pulse. The communication setting data is data that directly or indirectly represents the scheduled transmission time, which is determined based on information about the reference time. The communication setting data includes the ranging start time. The ranging start time is the start time of the ranging sequence. The ranging start time is a time determined based on the reference time. As an example, the ranging start time may be set to be several msec after the reference time.

[0040] The communication setting data also includes the number of blocks in the ranging sequence, the block length (in other words, the interval), the hopping key, the number of anchors 3, the number of rounds, and the round length. The technical significance of each parameter will be described separately below. The communication setting data also serves as information that serves as an agreement for performing the ranging sequence between the portable device 9 and the control unit 24. The control unit 24 generates a setting data set including the communication setting data and device oscillator error information, and controls the data to be transmitted to the anchor 3. The communication setting data may also include data indicating the total session time, which is the total time of the ranging sequence. The total session time may be determined based on the product of the number of blocks and the block length, as described below.

[0041] <Configuration of Anchor 3> As shown in FIG. 4 , the anchor 3 includes an in-vehicle communication unit 31, a UWB antenna 32, a transmission circuit 33, a reception circuit 34, an anchor control unit 35, an anchor oscillator 36, and a temperature sensor 37. The in-vehicle communication unit 31 is a component that enables the anchor 3 to communicate with the control unit 24. The anchor 3 corresponds to an in-vehicle device for ranging communication. The temperature sensor 37 is a sensor for measuring the temperature of the anchor oscillator 36. The temperature sensor 37 may measure the temperature around the anchor oscillator 36, or may measure the temperature of a predetermined portion of the anchor 3. Hereinafter, the term "anchor control unit 35" may be appropriately interchanged with the term "anchor 3." The UWB antenna 32 corresponds to a first communication unit for performing ranging communication. The in-vehicle communication unit 31 corresponds to a second communication unit for communicating with the ranging ECU 2.

[0042] The anchor oscillator 36 is electrically connected to the transmitting circuit 33, the receiving circuit 34, and the anchor control unit 35. The anchor oscillator 36 functions as a clock signal source. The anchor control unit 35 has a function of measuring time based on the output signal of the anchor oscillator 36. For example, the anchor oscillator 36 measures elapsed time by counting the clock signal generated by the anchor oscillator 36. The anchor oscillator 36 may be a ceramic oscillator or a crystal oscillator circuit including a crystal resonator. The anchor oscillator 36 may have a configuration similar to that of the device oscillator 98.

[0043] The anchor control unit 35 is configured to control the operations of the transmission circuit 33, the reception circuit 34, and the in-vehicle communication unit 31. The anchor control unit 35 includes a CPU, a memory, a ROM, and a communication IF.

[0044] The anchor 3 has, as its operating states, a standby state in which it can receive UWB pulses and a stop state in which it cannot receive UWB pulses. The standby state in which it can receive UWB pulses may be a state in which the receiving circuit 34 is operating. Specifically, it may be a state in which it can sample a received signal and perform processing based on the sampled signal. The standby state may be interpreted as a state in which the receiving amplifier and filter in the receiving circuit 34 are turned on. Furthermore, the standby state may be a state in which the anchor 3 can perform subsequent processing, such as determining whether a signal received via the UWB antenna 32 is a desired signal or confirming information contained in the signal. The anchor 3 may be in the standby state multiple times during the ranging sequence.

[0045] The stopped state may be a state in which the receiving circuit 34 is not operating. Specifically, it may be a state in which sampling of a received signal is not performed, or a state in which sampling is performed but subsequent processing of the sampled signal is not performed. For example, the stopped state may be a state in which the receiving amplifier and filter in the receiving circuit 34 are turned off. Furthermore, the stopped state may be a state in which the anchor 3 does not perform subsequent processing such as determining whether a signal received via the UWB antenna 32 is a desired signal or checking information contained in the signal. In addition, the anchor 3 may have, as an operating state, a transmission state in which it is capable of transmitting UWB pulses. The anchor control unit 35 controls switching the operating state of the anchor 3.

[0046] The anchor control unit 35 acquires anchor temperature information, which is information related to the temperature of the anchor 3 measured by the temperature sensor 37. The anchor control unit 35 stores, in its own ROM, anchor characteristic data, which is data for identifying an error in the anchor oscillator 36 caused by temperature. The error in the anchor oscillator 36 is an error in the frequency of the anchor oscillator 36. The frequency error in the anchor oscillator 36 is, for example, the difference between the nominal frequency and the actual frequency of the anchor oscillator 36. The anchor characteristic data may be a table or map indicating the amount of error according to temperature. The anchor characteristic data may also be a function / program that takes temperature as input and outputs the amount of error.

[0047] In this embodiment, in order to reduce the influence of the error of the anchor oscillator 36, the anchor control unit 35 acquires anchor oscillator error information, which is information related to the error of the anchor oscillator 36. The anchor oscillator error information is information that directly or indirectly represents the error of the device oscillator 98. The anchor control unit 35 identifies the value of the frequency error of the anchor oscillator 36 based on the acquired anchor temperature information and the value of the frequency error of the anchor oscillator 36 that corresponds to the stored temperature. In this embodiment, the value of the frequency error of the anchor oscillator 36 corresponds to the anchor oscillator error information.

[0048] The anchor control unit 35 determines the transition timing, which is the timing to enter the standby state, or the duration of the standby state, based on the communication setting data, device oscillator error information, and anchor oscillator error information. The duration of the standby state is the time from when the anchor 3 enters the standby state until when it enters the stopped state. Specifically, the anchor control unit 35 identifies the scheduled transmission time based on the communication setting data. Then, the anchor control unit 35 determines the amount of correction for the scheduled transmission time based on the device oscillator error information and anchor oscillator error information, and determines the transition timing or the duration based on the amount of correction.

[0049] <Regarding Mounting Positions of Anchors 3> The in-vehicle system 1 is provided with a plurality of anchors 3a, 3b, 3c, and 3d. Fig. 5 is a diagram showing an example of the arrangement of the plurality of anchors 3. Anchor 3a is provided at the right corner of the front bumper. Anchor 3b is provided at the left corner of the front bumper. Anchor 3c is provided at the right corner of the rear bumper. Anchor 3d is provided at the left corner of the rear bumper.

[0050] <Ranging Communication> Here, we will explain ranging communication performed between the portable device 9 and the vehicle Hv. Ranging communication is communication for measuring the distance between the portable device 9 and the vehicle Hv based on the propagation time (in other words, the flight time) of radio waves from the anchor 3 to the portable device 9. Ranging communication may include the portable device 9 transmitting and receiving ranging radio signals to and from multiple anchors 3. The ranging radio signals may be UWB pulses. One ranging communication can measure the distance from the anchor 3 to the portable device 9 once. The ranging sequence may be interpreted as a process of continuously measuring the distance between the portable device 9 and the vehicle Hv by repeatedly performing ranging communication approximately periodically. Continuous measurement makes it possible to understand changes in the distance of the portable device 9 over time.

[0051] As shown in FIG. 7, ranging communication generally includes four processes, steps S11 to S14. In this embodiment, the portable device 9 operates as an initiator, and each anchor 3 operates as a responder. Although only one anchor 3 is shown in FIG. 7, the other anchors 3 operate in the same manner. Note that the initiator here is a device that starts communication, in other words, a device that requests a response. A responder is a device that replies to a response from the initiator.

[0052] Step S11 is a step in which the portable device 9 transmits a poll signal to all anchors 3. The poll signal is a signal that requests the anchors 3 to return a response. Step S12 is a step in which the anchors 3 transmit a response signal upon receiving the poll signal. The anchors 3 that receive the poll signal return a response signal immediately after receiving the poll signal or at a specific timing. The response signal may be referred to as an answer signal.

[0053] Step S13 is a step in which the portable device 9 broadcasts a final signal. The final signal is a signal for the anchor 3 to measure a round trip time (RTT) and may be a type of signal that does not require a response signal to be sent back. The final signal may be a response signal to a response signal. The final signal may be transmitted to all anchors 3 (in other words, vehicles Hv). The portable device 9 may transmit the final signal at a specific predetermined timing, such as a predetermined time after transmitting a poll signal.

[0054] Step S14 is a step in which the portable device 9 broadcasts a final data signal. The final data signal may be a signal notifying that the current ranging communication is to be terminated. The final data signal may include a device measurement result generated by the portable device 9. The device measurement result may be data indicating the distance from the portable device 9 to each anchor 3.

[0055] The final data signal may also include information indicating an intra-device delay time (ΔT2 in the figure), which is the time from receiving a response signal to transmitting a final signal. The response signal is received at a different time from each anchor 3. Therefore, the final data signal may include data on the intra-device delay time for each anchor 3.

[0056] In response to the final signal, each anchor 3 may transmit to the mobile device 9 a signal indicating an intra-anchor delay time (ΔT1 in the figure), which is the time from receiving a poll signal to returning a response signal. The signal indicating the intra-anchor delay time may be transmitted between the transmission of the final signal and the final data signal. Furthermore, the anchor 3 may transmit a UWB signal including transmission source information and the intra-anchor delay time as a response signal.

[0057] By performing the above-described ranging communication, the mobile device 9 can acquire a first round trip time (hereinafter referred to as the first RTT), which is the elapsed time from transmitting a poll signal to receiving a response signal. RTT1 in the figure represents the first RTT. The first RTT is a value obtained by combining the time of flight (ToF) of radio waves corresponding to the distance from the mobile device 9 to the anchor 3 and the intra-anchor delay time. The intra-anchor delay time may be a parameter derived from the hardware constituting the anchor 3. The intra-anchor delay time may be measured by the anchor 3 and notified to the mobile device 9 by the anchor 3 at a predetermined timing. From the intra-anchor delay time and the observed value of the first RTT, the mobile device 9 can calculate the one-way flight time. The distance from the mobile device 9 to the anchor 3 can be calculated from the flight time using the propagation speed of radio waves. In this way, the mobile device 9 can generate device measurement results indicating the distance from the mobile device 9 to each anchor 3 based on the results of the ranging communication.

[0058] Furthermore, through the ranging communication, the anchor 3 can acquire a second round trip time (hereinafter also referred to as the second RTT), which is the elapsed time from transmitting the response signal to receiving the final signal. RTT2 in the figure indicates the second RTT. The second RTT includes the intra-device delay time in addition to the ToF. If the final data signal includes information regarding the intra-device delay time for each anchor 3, the anchor 3 can determine the intra-device delay time for that anchor 3 by referring to the final data signal. Therefore, the anchor 3 itself can also generate data indicating the distance from the anchor 3 to the mobile device 9 through the ranging communication (hereinafter referred to as the anchor measurement result). The anchor measurement result corresponds to the ranging result described above. The anchor measurement result includes the ranging value and information indicating the mobile device 9 that performed the measurement. The anchor measurement result may be generated for each anchor 3.

[0059] <Outline of the Distance Measurement Sequence> The distance measurement sequence will be described with reference to FIG. 8 . The distance measurement ECU 2 and the portable device 9 determine a reference time and a distance measurement start time by transmitting and receiving a request signal prior to distance measurement. The distance measurement ECU 2 sets the time at which it receives a response signal to the request signal as the reference time (t0 in FIG. 8 ). The portable device 9 sets the time at which it transmits a response signal to the request signal as the reference time. The reference time is the time at which each device recognizes and sets a common distance measurement start time. The distance measurement start time is the time at which periodic distance measurement communication starts. As described above, the distance measurement start time (t1 in FIG. 8 ) is set a predetermined time after the reference time. A parameter (i.e., data) indicating the length from the reference time to the distance measurement start time may be included in the request signal or may be pre-registered in each device. In this way, the reference time corresponds to the time for determining the start time of the distance measurement sequence. The reference time may be interpreted as the origin of the time axis of the distance measurement sequence.

[0060] The ranging start time is also called UWB time zero. After the ranging start time, ranging communication is repeated approximately periodically. Specifically, after the ranging start time, the time is divided into blocks, and ranging communication is performed once for each block.

[0061] As shown in FIG. 9 , a block is further divided into multiple rounds. A round is a block divided by a predetermined number of rounds. FIG. 9 shows an example in which the number of rounds is 12, and one block is divided into 12 rounds. The round number in which ranging communication is performed is determined by a hopping key. The hopping key is a parameter for determining the round number in which ranging communication is performed within a block. In other words, once the reference time, ranging start time, and hopping key are determined, the timing (in other words, the time) in which ranging communication is performed is uniquely determined. The reference time is the time that serves as the reference for the ranging start time, but it can also be interpreted as the time that serves as the reference for performing intermittent / repeated ranging communication.

[0062] In a ranging sequence, ranging communication is performed multiple times. For example, one ranging sequence includes 12 blocks. In this case, ranging communication is performed intermittently 12 times in one ranging sequence. The entire ranging sequence is also referred to as one session. The reference time is also the time that serves as the reference for one session. One session includes a predetermined number of blocks, and one block includes multiple rounds.

[0063] The number of blocks included in the communication setting data indicates the number of blocks included in one session. The block length is the length of the block and is sometimes called the interval. The hopping key is a parameter used to change the round number for ranging communication for each block. The number of rounds indicates the number of rounds that make up one block. The round length indicates the length of one round. The length of one block (i.e., block length / interval) is determined by determining the round length and number of rounds. Additionally, the total session time can be determined by determining the number of blocks and block length.

[0064] Note that one round may be further divided into multiple time slots with a granularity of one millisecond or several milliseconds. Each time slot may have a different purpose. For example, one round may include a time slot for transmitting a poll signal, a time slot for the anchor 3a to return a response, and the like. The allocation of time slots may be designed as appropriate.

[0065] <Issues Due to Errors> Here, we will explain the issues that arise due to oscillator errors in the ranging sequence. Figure 10 is a diagram showing the effects of oscillator errors. The horizontal axis of Figure 10 represents time. Here, we consider a case where an oscillator error occurs in at least one of the device oscillator 98 and the anchor oscillator 36.

[0066] The device control unit 93 identifies the scheduled transmission time based on the reference time / ranging start time and the hopping key. The device control unit 93 controls the transmission of UWB pulses at the identified scheduled transmission time. Similarly, the anchor 3 identifies the scheduled transmission time based on the reference time / ranging start time and the hopping key. The device control unit 93 and the anchor 3 share the same reference time / ranging start time and hopping key. Therefore, the scheduled transmission time identified by the device control unit 93 and the scheduled transmission time identified by the anchor 3 will match.

[0067] The anchor 3 transitions to a standby state in which it is able to receive UWB pulses based on the identified scheduled transmission time. When a duration has elapsed since transitioning to the standby state, the anchor 3 transitions to a stopped state. RX in Fig. 10 indicates the period during which the anchor 3 is in the standby state. In other words, the length of the RX time corresponds to the duration of the standby state.

[0068] The portable device 9 and the anchor 3 measure the time from the reference time or the ranging start time to the scheduled transmission time based on their respective oscillators. Td in FIG. 10 represents the scheduled transmission time measured by the portable device 9 based on the device oscillator 98. In other words, Td is the actual time (timing) corresponding to the scheduled transmission time measured by the portable device 9. Ta in FIG. 10 represents the scheduled transmission time measured (or predicted) by the anchor 3 based on the anchor oscillator 36. In other words, Ta is the actual time (timing) corresponding to the scheduled transmission time measured by the anchor 3. The portable device 9 transmits a UWB pulse at time Td. The anchor 3 is controlled to transition to a standby state from time Tb, which is a predetermined time before time Ta. Tb in FIG. 10 corresponds to the transition timing at which the anchor 3 transitions to the standby state. The transition timing may be interpreted as the timing at which the anchor 3 transitions from a stopped state to a standby state.

[0069] At this time, if an oscillator error occurs in at least one of the device oscillator 98 and the anchor oscillator 36, a discrepancy will occur between the time measured by the portable device 9 and the time measured by the anchor 3. In other words, as shown in Fig. 10, even if the same scheduled transmission time is measured, a discrepancy will occur between the actual time (timing) corresponding to the scheduled transmission time measured by the portable device 9 and the anchor 3. If a discrepancy occurs between time Td and time Ta, a discrepancy will occur between the timing at which the portable device 9 transmits the UWB pulse and the timing at which the anchor 3 enters a standby state. This may result in the anchor 3 being unable to receive the UWB pulse.

[0070] <Addressing Issues Due to Errors> As will be described later, in this embodiment, the issue of oscillator errors is addressed by exchanging device oscillator error information and anchor oscillator error information between the portable device 9 and the anchor 3. The device oscillator error information and the anchor oscillator error information will hereinafter also be collectively referred to as error-related information.

[0071] Based on the error-related information, the anchor 3 estimates (in other words, acquires) the time difference between the actual time Td corresponding to the scheduled transmission time measured by the portable device 9 and the actual time Ta corresponding to the scheduled transmission time measured by the anchor 3. Hereinafter, the time difference between the actual time Td corresponding to the scheduled transmission time measured by the portable device 9 and the actual time Ta corresponding to the scheduled transmission time measured by the anchor 3 will be referred to as ΔTc. Based on the acquired time difference ΔTc, the anchor 3 corrects the scheduled transmission time from the originally calculated time Ta to time Tα. Along with this correction, the transition timing is also corrected to time Tβ, which is a predetermined time before the corrected scheduled transmission time Tα. By performing this correction, the anchor 3 is more likely to receive the UWB pulse.

[0072] The correction method is not limited to the above. For example, the anchor 3 acquires the actual time Td corresponding to the scheduled transmission time measured by the portable device 9 based on the error-related information. Then, the anchor 3 may determine or correct the transition timing so that the anchor 3 enters the standby state at Tβ, a predetermined time before the time Td. In this case, the anchor 3 uses the anchor oscillator error information so that the anchor 3 enters the standby state at the actual time Tβ. The anchor 3 may be configured to measure the elapsed time from the reference time / ranging start time using the error-related information. In the example of FIG. 11 , the transition timing Tβ is corrected as an example of correction, but instead of this correction, a correction may be made to lengthen the duration of the standby state of the anchor 3. Furthermore, a correction may be made to lengthen the duration after correcting the transition timing Tβ. In this case, the anchor 3 is also likely to receive the UWB pulse.

[0073] The correction amount based on the error-related information (≒ time difference ΔTc) may be determined based on the value obtained by multiplying the difference in the output intervals of clock signals between devices by the number of clocks corresponding to the scheduled transmission time Ta. The scheduled transmission time Ta is a parameter corresponding to the amount of time elapsed from a reference time / ranging start time. In other words, the above configuration corresponds to a configuration in which the correction amount is determined based on the difference in the output intervals of clock signals between devices and the elapsed time from the reference time, etc. The correction amount may be determined based on the error that may occur per unit time and the time to be corrected. The correction amount may be determined using any method so that it matches the time difference ΔTc.

[0074] 12 is a sequence diagram showing the operation of the vehicle Hv from establishing communication to completing the distance measurement sequence. The portable device 9 shown in FIG. 12 is assumed to be sufficiently far away from the vehicle Hv at the start of the sequence shown in FIG. 12, and the portable device 9 and the vehicle Hv are not connected for communication.

[0075] In step S21 shown in Figure 12, the portable device 9 and the ranging ECU 2 establish a communication connection. This communication connection means establishing an SRWC communication link. Then, the portable device 9 transmits an SRWC signal corresponding to a request signal to the ranging ECU 2 using the SRWC (S22). The ranging ECU 2 receives a response signal to the request signal from the portable device 9 using the SRWC (S23). The portable device 9 uses the time at which the response signal is transmitted as the reference time.

[0076] The response signal includes data defining the reference time, and the ranging ECU 2 uses the time at which the response signal is received as the reference time. The response signal includes setting information and device oscillator error information. The setting information is information regarding the settings for implementing the ranging sequence. The setting information may include some or all of the parameters that make up the communication setting data. The setting information received from the portable device 9 may also be referred to as received setting data. The ranging ECU 2 generates communication setting data based on the received setting data. The ranging ECU 2 may also generate a setting data set from the received setting data to be distributed directly to the anchor 3.

[0077] The ranging ECU 2 transmits a setting data set to each anchor 3 (S24). The setting data set is a data set including information for the anchor 3 to calculate the timing at which ranging communication will be performed, i.e., the scheduled transmission time. The setting data set includes part or all of the communication setting data and device oscillator error information. The communication setting data included in the setting data set may be the ranging start time, the number of blocks, the hopping key, the round length, and the number of rounds, etc. The communication setting data included in the setting data set corresponds to data for calculating the provisional value of the scheduled transmission time, and the device oscillator error information corresponds to data for correcting the provisional value of the scheduled transmission time. The setting data set may include the total time of the ranging sequence.

[0078] After receiving the setting data set, the anchor 3 acquires the anchor oscillator error information (S25). The same operation is performed by each anchor 3.

[0079] The anchor 3 determines and corrects the transition timing or duration based on the communication setting data and the error-related information (S26). Specifically, the anchor 3 identifies the scheduled transmission time based on the communication setting data and sets the identified time as a provisional value for the scheduled transmission time. The provisional value corresponds to the time Ta described above. The anchor 3 then determines a correction amount for the provisional value of the scheduled transmission time based on the error-related information. Thereafter, the anchor 3 determines a final scheduled transmission time (Tα) based on the provisional value of the scheduled transmission time and the correction amount. The final scheduled transmission time is the scheduled transmission time after correction. The final scheduled transmission time corresponds to the time Ta described above.

[0080] The anchor 3 determines the transition timing or duration based on the final scheduled transmission time. For example, the transition timing is set to a time a predetermined time before the final scheduled transmission time. The transition timing may be set so that the final scheduled transmission time is located in the middle of the period during which the anchor 3 maintains a standby state. The transition timing may also be the same time as the final scheduled transmission time. The duration may be corrected according to the amount of correction made to the provisional value of the scheduled transmission time. For example, the greater the amount of correction made to the provisional value of the scheduled transmission time, the longer the duration may be corrected.

[0081] The anchor 3 transitions to a standby state at the transition timing determined based on the correction amount (S27).Then, the standby state continues for the duration determined based on the correction amount (S28).When the duration has elapsed, the anchor 3 ends the reception standby state (S29).

[0082] If the anchor 3 receives the UWB pulse (YES in S30), it performs recorrection (S31). Specifically, the anchor 3 determines the transition timing or duration for the next block based on the transition timing determined based on the correction amount and the actual timing of receiving the UWB pulse. FIG. 13 is a diagram illustrating an overview of recorrection. For example, the anchor 3 determines the next transition timing based on the difference ΔTe between the predicted scheduled transmission time (Tα) and the actual time Tq of receiving the UWB pulse. The next transition timing is the timing of transitioning to reception standby when performing ranging communication in the block following the current block. The anchor 3 recorrects and determines the next transition timing based on the provisional scheduled transmission time based on the communication setting data, the correction amount based on the error-related information, and ΔTe. "Tα" in FIG. 13 represents the scheduled transmission time of the UWB pulse (in other words, the scheduled reception time) taking into account the clock error. "Tq" in FIG. 13 represents the actual reception time.

[0083] When the vehicle Hv completes the distance measurement sequence (S32) and further completes the communication connection (S33), it terminates all processing related to the distance measurement sequence and distance measurement communication.

[0084] <Effects> The distance at which SRWC is possible and the distance at which UWB communication is possible may differ. For example, SRWC communication is possible even at a distance of 10 meters or more, while the distance at which UWB communication is possible may be less than 5 meters. In other words, the range at which a ranging request can be transmitted and received differs from the range at which ranging communication is actually possible. Due to the difference in the communicable distance, it is possible that the anchor 3 will not actually be able to receive a UWB signal from the portable device 9 until the latter half or end of the session after the ranging start time. The longer the elapsed time from the ranging start time, the larger the time difference ΔTc becomes. Therefore, if the portable device 9 enters the UWB communication range of the anchor 3 at the end of the session, the larger the time difference ΔTc is compared to the beginning of the session, and ranging communication may fail even though the portable device 9 is in the UWB communication range of the anchor 3.

[0085] Such communication failures are more likely to occur the longer the session lasts. Because the anchors 3 are distributed throughout the vehicle, the timing at which each anchor 3 becomes capable of UWB communication with the portable device 9 may differ. For example, an anchor 3 located at the front end of the vehicle may be able to receive UWB signals from the portable device 9 from the beginning of the session, while an anchor 3 located at the rear end / inside the vehicle may become capable of UWB communication with the portable device 9 only later in the session. To address this issue, the above configuration corrects the timing at which the anchor 3 enters a standby state based on error-related information. This reduces the risk of ranging communication failure.

[0086] In addition, in this embodiment, the ranging ECU 2 transmits device oscillator error information to the anchor 3 in addition to the communication setting data. The anchor 3 then determines the transition timing or duration based on the communication setting data and error-related information. In other embodiments, the ranging ECU 2 may determine the timing or duration. However, in other embodiments, the anchor 3 must transmit the anchor oscillator error information to the ranging ECU 2. In contrast to such other embodiments, in this embodiment, the anchor 3 determines the transition timing and duration, so the anchor 3 does not need to transmit the anchor oscillator error information to the control device. Furthermore, the ranging ECU 2 does not need to determine the timing or duration. This reduces the processing time of the anchor 3 and the ranging ECU 2.

[0087] In this embodiment, the transition timing or duration of the next block is determined based on the timing at which the UWB pulse was actually received, thereby reducing the influence of errors in the device oscillator 98 and the anchor oscillator 36. This allows the next timing or duration to be determined more accurately, thereby preventing failures in receiving UWB pulses.

[0088] In this embodiment, the ranging ECU 2 receives a response signal including data defining the reference time and device oscillator error information from the portable device 9. This eliminates the need for separate communication for the control device to receive the reference time and device oscillator error information, thereby reducing the time required for ranging communication.

[0089] Furthermore, the influence of oscillator errors becomes cumulatively greater as time passes. In this embodiment, the transition timing or duration is determined based on the communication setting data, error-related information, and elapsed time. The elapsed time is the time elapsed from a predetermined time determined based on a reference time. The predetermined time determined based on the reference time may be, for example, the distance measurement start time. The predetermined time determined based on the reference time may be the reference time itself. The anchor 3 may acquire the elapsed time based on the output signal of the anchor oscillator 36. In step 26 of FIG. 12, the anchor 3 may determine and correct the transition timing or duration based on the communication setting data, error-related information, and elapsed time. The anchor 3 determines the correction amount for the provisional scheduled transmission time based on the error-related information and the elapsed time. For example, the longer the elapsed time, the greater the correction amount for the transition timing. Alternatively, the longer the elapsed time, the longer the duration may be.

[0090] According to this embodiment, the anchor 3 determines the transition timing or duration based on the elapsed time in addition to the communication setting data and the error-related information. This makes it possible to suppress the influence of oscillator errors, which become increasingly larger as time passes. Note that in other embodiments, the correction amount may be a fixed value. The correction amount may be a fixed value obtained by combining the communication setting data and the error-related information.

[0091] <Variation 1> The anchor 3 may determine the transition timing or duration based on the error-related information and the elapsed time, as well as the total session time. The total session time is the time from a predetermined timing determined based on a reference time to the end of the ranging sequence. The total session time may be the time from the reference time to the end of the ranging sequence, or may be the time from the start of ranging to the end of the ranging sequence. The end of the ranging sequence may be the end of the final round in the final block of the ranging sequence. The end of the ranging sequence may be the end of the round in which the anchor 3 performs the final ranging communication in the ranging sequence. Furthermore, the end of the ranging sequence may be the same for each anchor 3, or may be different.

[0092] In step 26 of Figure 12, the anchor 3 may determine and correct the transition timing or duration based on the communication setting data, error-related information, duration, and total session time. The anchor 3 determines the amount of correction to the provisional value of the scheduled transmission time based on the error-related information, elapsed time, and total session time. For example, the longer the total session time, the greater the amount of correction to the transition timing. Alternatively, the longer the total session time, the longer the duration.

[0093] According to this modification, the anchor 3 determines the transition timing or duration based on the total session time in addition to the communication setting data, the error-related information, and the elapsed time, thereby suppressing the influence of oscillator errors that become cumulatively larger as time passes.

[0094] <Variation 2> In the embodiment, the transition timing or duration is determined by the anchor 3, but the ranging ECU 2 may also determine it. In other words, the ranging ECU 2 may acquire anchor oscillator error information from the anchor 3 and determine the transition timing or duration based on the communication setting data and error-related information. The anchor oscillator error information is the frequency value of the anchor oscillator 36, the temperature value of the anchor 3, or information indirectly representing these. The anchor oscillator error information may be any information that allows the ranging ECU 2 to determine the error of the anchor oscillator 36.

[0095] In this modified example, the ranging ECU 2 acquires anchor temperature information from the anchor 3 as anchor oscillator error information. The processor 241 of the control unit 24 stores anchor characteristic data for each anchor 3. The ranging ECU 2 determines the value of the frequency error of the anchor oscillator 36 based on the acquired anchor temperature information and the value of the frequency error of the anchor oscillator 36 corresponding to the stored temperature. A configuration in which the ranging ECU 2 determines and instructs the transition timing or duration for each anchor 3 reduces the processing load on the anchor 3.

[0096] After receiving the response signal in step S23, the ranging ECU 2 may transmit a signal requesting anchor oscillator error information to each anchor 3. In this case, the anchor 3 transmits the anchor oscillator error information upon receiving the request from the ranging ECU 2. As shown in FIG. 14, after step S23, the ranging ECU 2 may acquire the anchor oscillator error information from each anchor 3 (S40).

[0097] Additionally, the ranging ECU 2 may determine the transition timing or duration based on the communication setting data and error-related information (S41). Specifically, first, the ranging ECU 2 identifies the frequency error value of each anchor oscillator 36 based on the acquired anchor temperature information. Then, the ranging ECU 2 identifies the scheduled transmission time based on the communication setting data and sets the identified time as a provisional value of the scheduled transmission time. The provisional value corresponds to the aforementioned time Ta. Then, the ranging ECU 2 determines the correction amount for the provisional value of the scheduled transmission time based on the frequency error value of the anchor oscillator 36 acquired based on the device oscillator error information and the anchor temperature information.

[0098] The distance measurement ECU 2 then determines the final scheduled transmission time (Tα) based on the provisional value of the scheduled transmission time and the correction amount. Furthermore, the distance measurement ECU 2 determines the transition timing or duration based on the final scheduled transmission time. This process of determining the transition timing or duration (S41) is performed for each anchor 3.

[0099] The ranging ECU 2 transmits a setting data set to each anchor 3 (S41). The setting data set includes information on the transition timing or duration. Each anchor 3 transitions to a standby state based on the received information on the transition timing or duration (S42).

[0100] In this modification, the distance measurement ECU 2 determines the transition timing or duration for each anchor 3, eliminating the need for the anchor 3 to determine the timing or duration. This reduces the processing load on the anchor 3.

[0101] <Modification 3> In the embodiment, the device control unit 93 transmits a specific value of the error of the device oscillator 98 to the vehicle Hv as the device oscillator error information, but this is not limited to this. The device control unit 93 may transmit a specific value of the frequency of the device oscillator 98, a temperature value of the portable device 9, or information indirectly representing these, as the device oscillator error information. In this modification, the device control unit 93 transmits device temperature information to the vehicle Hv as the device oscillator error information.

[0102] In this modification, the processor 241 of the control unit 24 stores device characteristic data. The control unit 24 identifies the value of the frequency error of the device oscillator 98 based on the acquired device temperature information and device characteristic data. The control unit 24 then includes the identified frequency error value as device oscillator error information in a communication data set and transmits it to the anchor 3.

[0103] In this modification, the control unit 24 identifies the value of the frequency error of the device oscillator 98, so there is no need for the portable device 9 to identify the value of the frequency error of the device oscillator 98. This reduces the processing load on the portable device 9.

[0104] <Other Modifications> Temperature is not the only factor that can cause errors in the oscillator frequency. The oscillation frequency of an oscillator can also deviate from the nominal frequency due to factors such as aging, tolerances of the capacitors that adjust the oscillator, and reflow stress. Such information may be used as device error information or anchor oscillator error information. For example, information related to aging, such as the manufacturing year of the oscillator, may be transmitted.

[0105] A step of transmitting a pre-poll signal (Pre-Poll) may be provided before step S11 of the ranging communication. The pre-poll signal is a UWB signal that notifies the other party of the upcoming start of ranging.

[0106] At the time of shipping from the factory, the frequency value and frequency error of the anchor oscillator 36 may be measured and stored in the ROM of the anchor control unit 35. The stored value may be used as anchor oscillator error information.

[0107] Although the ranging ECU 2 transmits the setting data set including the ranging start time to each anchor 3, this is not limited to this. For example, the setting data set may include data indicating a reference time or another starting time instead of the ranging start time. Data indicating the reference time or another starting time also corresponds to communication setting data. For example, an offset time that defines the reference time and the ranging start time may be included in the setting data set and transmitted to each anchor 3. Then, the anchor 3 may obtain the ranging start time based on the offset time that defines the reference time and the ranging start time. Alternatively, the anchor 3 may directly identify the scheduled transmission time based on the offset time that defines the reference time and the ranging start time without determining the ranging start time.

[0108] In the embodiment, the scheduled transmission time is a time determined based on a reference time, but the scheduled transmission time may also be based on the ranging start time. The ranging start time is a time determined based on the reference time. Therefore, even when the ranging start time is used as the reference, it is equivalent to a time determined based on the reference time. The above-mentioned elapsed time may be the time elapsed from the reference time or the time elapsed from the ranging start time.

[0109] In the embodiment, the time when the response signal is transmitted or received is used as the reference time, but this is not limited thereto. The reference time may be a time a predetermined time has elapsed since the time when the response signal is transmitted or received. The reference time may be determined in any way as long as it is a time that is shared by the portable device 9 and the ranging ECU 2.

[0110] In the embodiment, the transition timing or duration is determined based on error-related information, i.e., device oscillator error information and anchor oscillator error information. Here, the error-related information may be only device error information or only anchor error information. Furthermore, the error-related information does not necessarily have to include both device error information and anchor error information; it may be only one of them.

[0111] The in-vehicle system 1 may optionally acquire the device oscillator error information from the portable device 9 and may therefore be omitted. The anchor 3 / ranging ECU 2 may be configured to adjust the transition timing or duration based on the anchor oscillator error information without using the device oscillator error information.

[0112] The in-vehicle device for ranging communication is not limited to a device mounted on a vehicle, but may be broadly interpreted as a device used in a vehicle. The in-vehicle device may be a device that can be attached to or detached from the vehicle. The in-vehicle device may be a device that is attached to the vehicle by a user or a device that is brought into the vehicle.

[0113] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0114] (Technical Idea 1) An in-vehicle system configured to be able to perform ranging communication with a portable device (9) using UWB pulses, comprising: a control device (2) configured to be able to wirelessly communicate with the portable device; and an anchor (3) configured to be able to communicate with the control device and to be able to perform the ranging communication with the portable device, wherein the control device: acquires, by communication with the portable device, a reference time that is a time used as a reference for performing the ranging communication, and device oscillator error information that is information regarding an error of a device oscillator (98) that is an oscillator possessed by the portable device; acquires communication setting data that can specify a scheduled transmission time that is a time at which the portable device will transmit UWB pulses, the scheduled transmission time being determined based on the reference time information; and transmits the communication setting data to the anchor, wherein the anchor: has, as its operating states, a standby state in which it is able to receive UWB pulses, and a stop state in which it is unable to receive UWB pulses; has an anchor oscillator (36) that is an oscillator; has a function of measuring time based on an output signal of the anchor oscillator; acquires anchor oscillator error information that is error information of the anchor oscillator; An in-vehicle system, wherein a transition timing at which the anchor enters the standby state or a duration of the standby state is determined based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

[0115] (Technical Idea 2) The control device transmits the device oscillator error information to the anchor in addition to the communication setting data, and the anchor determines the transition timing or the duration based on the communication setting data, the device oscillator error information, and the anchor oscillator error information. This is the in-vehicle system described in Technical Idea 1.

[0116] (Technical Idea 3) The anchor identifies the scheduled transmission time based on the communication setting data, determines a correction amount for the scheduled transmission time based on the device oscillator error information and the anchor oscillator error information, and determines the transition timing or the duration based on the correction amount, in the in-vehicle system described in Technical Idea 2.

[0117] (Technical Idea 4) The control device is configured to intermittently perform the ranging communication multiple times after the reference time at timing determined based on the reference time, and the anchor acquires the elapsed time, which is the time that has passed since a predetermined time determined based on the reference time, based on the output signal of the anchor oscillator, and determines the transition timing or the duration based on the elapsed time in addition to the communication setting data, the device oscillator error information, and the anchor oscillator error information, in an in-vehicle system described in Technical Idea 2 or 3.

[0118] (Technical Idea 5) The control device is configured to intermittently perform the ranging communication multiple times after the reference time at timing determined based on the reference time, and the anchor, when it is able to receive a UWB pulse, determines the next transition timing or the duration based on the communication setting data, the device oscillator error information, and the anchor oscillator error information, as well as the transition timing and the timing at which the UWB pulse was actually received, in an in-vehicle system described in any one of Technical Ideas 2 to 4.

[0119] (Technical Idea 6) The in-vehicle system according to any one of Technical Ideas 1 to 5, wherein the control device transmits a request signal to the portable device requesting the start of the ranging communication, and receives a response signal from the portable device as a reply to the request signal, the response signal including data specifying the reference time and the device oscillator error information.

[0120] (Technical Idea 7) The anchor transmits the anchor oscillator error information to the control device, and the control device determines the transition timing or the duration based on the communication setting data, the device oscillator error information, and the anchor oscillator error information, and transmits the determined transition timing or the duration to the anchor. This is the in-vehicle system described in Technical Idea 1.

[0121] (Technical Idea 8) The in-vehicle system according to any one of Technical Ideas 1 to 7, wherein the device oscillator error information is information relating to the temperature of the portable device, and the anchor oscillator error information is information relating to the temperature of the anchor.

[0122] (Technical Concept 9) The in-vehicle system according to any one of Technical Concepts 1 to 8, comprising a plurality of the anchors.

[0123] (Technical Idea 10) An in-vehicle system described in any one of Technical Ideas 1 to 9, wherein the control device is configured to be able to perform wireless communication with the portable device using a second communication method that is a communication method different from a first communication method that is a communication method used in the ranging communication, and the control device controls to start the ranging communication based on the establishment of a communication connection with the portable device through communication using the second communication method.

[0124] (Technical Idea 11) An in-vehicle device comprising: a first communication unit (32) for performing ranging communication with a portable device using UWB pulses; and a second communication unit (31) for communicating with a control device (2); and having, as operating states, a standby state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received; the in-vehicle device has an anchor oscillator (36) which is an oscillator; and has a function of measuring time based on an output signal of the anchor oscillator; acquires anchor oscillator error information which is error information of the anchor oscillator; acquires from the control device device oscillator error information which is information regarding the error of a device oscillator which is an oscillator possessed by the portable device, and communication setting data which can identify a scheduled transmission time which is the time at which the portable device will transmit UWB pulses, which is determined based on device oscillator error information which is information regarding the error of a device oscillator which is an oscillator possessed by the portable device, and a reference time which is the time used as a reference for performing the ranging communication; and determines a transition timing which is the timing to enter the standby state or a duration of the standby state based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

[0125] (Technical Idea 12) A method executed by an in-vehicle system that performs ranging communication with a portable device using UWB pulses, the in-vehicle system including a control device (2) and an anchor (3) having, as operating states, a standby state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received, the method including the control device acquiring, by communication with the portable device, a reference time and device oscillator error information that is information regarding an error of a device oscillator that is an oscillator possessed by the portable device, the control device generating communication setting data based on the reference time information, the control device transmitting the communication setting data to the anchor, acquiring anchor oscillator error information that is error information of an anchor oscillator (36) that is an oscillator possessed by the anchor, and determining a transition timing at which the anchor enters the standby state or a duration of the standby state based on the communication setting data, the device oscillator error information and the anchor oscillator error information.

[0126] (Technical Idea 13) An in-vehicle system configured to be able to perform ranging communication using UWB pulses with a portable device (9), comprising: a control device (2) configured to be able to wirelessly communicate with the portable device; and an anchor (3) configured to be able to communicate with the control device and to be able to perform the ranging communication with the portable device, wherein the control device: acquires a reference time, which is a time used as a reference for performing the ranging communication, by communicating with the portable device; acquires communication setting data that is able to specify a scheduled transmission time, which is a time at which the portable device will transmit UWB pulses, determined based on information about the reference time; and transmits the communication setting data to the anchor, wherein the anchor: has, as its operating states, a standby state in which it is able to receive UWB pulses, and a stopped state in which it is unable to receive UWB pulses; has an anchor oscillator (36) that is an oscillator; has a function of measuring time based on an output signal of the anchor oscillator; acquires anchor oscillator error information that is error information of the anchor oscillator; An in-vehicle system, wherein a transition timing, which is a timing at which the anchor enters the standby state, or a duration of the standby state is determined based on the communication setting data and the anchor oscillator error information.

Claims

1. An in-vehicle system configured to be capable of performing ranging communication using UWB pulses with a portable device (9), comprising: a control device (2) configured to be capable of wireless communication with the portable device; and an anchor (3) configured to be capable of communicating with the control device and to be capable of performing the ranging communication with the portable device, wherein the control device: acquires, by communication with the portable device, a reference time which is a time used as a reference for performing the ranging communication, and device oscillator error information which is information regarding an error of a device oscillator (98) which is an oscillator possessed by the portable device; acquires communication setting data which is capable of specifying a scheduled transmission time which is a time at which the portable device transmits UWB pulses, which is determined based on the reference time information; and transmits the communication setting data to the anchor, wherein the anchor: has, as its operating states, a standby state in which it is capable of receiving UWB pulses, and a stopped state in which it is unable to receive UWB pulses, has an anchor oscillator (36) which is an oscillator, and has a function of measuring time based on an output signal of the anchor oscillator; acquires anchor oscillator error information which is error information of the anchor oscillator; An in-vehicle system, wherein a transition timing, which is the timing at which the anchor enters the standby state, or a duration of the standby state is determined based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

2. The in-vehicle system of claim 1, wherein the control device transmits the device oscillator error information to the anchor in addition to the communication setting data, and the anchor determines the transition timing or the duration based on the communication setting data, the device oscillator error information and the anchor oscillator error information.

3. The in-vehicle system of claim 2, wherein the anchor: identifies the scheduled transmission time based on the communication setting data; determines a correction amount for the scheduled transmission time based on the device oscillator error information and the anchor oscillator error information; and determines the transition timing or the duration based on the correction amount.

4. The control device is configured to intermittently execute the ranging communication multiple times after the reference time at a timing determined based on the reference time, and the anchor obtains an elapsed time, which is the time that has elapsed from a predetermined time determined based on the reference time, based on the output signal of the anchor oscillator, and determines the transition timing or the duration based on the elapsed time in addition to the communication setting data, the device oscillator error information, and the anchor oscillator error information.

5. The control device is configured to intermittently execute the ranging communication multiple times after the reference time at a timing determined based on the reference time, and the anchor, when it receives a UWB pulse, determines the next transition timing or the duration based on the communication setting data, the device oscillator error information, and the anchor oscillator error information, as well as the transition timing and the timing when the UWB pulse is actually received. The in-vehicle system described in claim 2.

6. The in-vehicle system of claim 1, wherein the control device transmits a request signal to the portable device requesting the initiation of the ranging communication, and receives a response signal from the portable device in response to the request signal, the response signal including data defining the reference time and the device oscillator error information.

7. The in-vehicle system of claim 1, wherein the anchor transmits the anchor oscillator error information to the control device, and the control device determines the transition timing or the duration based on the communication setting data, the device oscillator error information, and the anchor oscillator error information, and transmits the determined transition timing or the duration to the anchor.

8. The in-vehicle system of claim 1, wherein the device oscillator error information is information relating to a temperature of the portable device, and the anchor oscillator error information is information relating to a temperature of the anchor.

9. The in-vehicle system of claim 1, comprising a plurality of said anchors.

10. The in-vehicle system of claim 1, wherein the control device is configured to be capable of wireless communication with the portable device using a second communication method that is a communication method different from a first communication method that is a communication method used in the ranging communication, and the control device controls to start the ranging communication based on the establishment of a communication connection with the portable device through communication using the second communication method.

11. An in-vehicle device comprising: a first communication unit (32) for carrying out ranging communication with a portable device using UWB pulses; and a second communication unit (31) for communicating with a control device (2); and having as its operating states a standby state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received; the in-vehicle device has an anchor oscillator (36) which is an oscillator; and has a function of measuring time based on an output signal of the anchor oscillator; acquires anchor oscillator error information which is error information of the anchor oscillator; acquires from the control device device oscillator error information which is information on the error of a device oscillator which is an oscillator possessed by the portable device, and communication setting data which can specify a scheduled transmission time which is the time when the portable device will transmit a UWB pulse, which is determined based on a reference time which is the time used as the reference for carrying out the ranging communication; and determines a transition timing which is the timing to enter the standby state, or a duration of the standby state, based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

12. A method executed by an in-vehicle system that performs ranging communication with a portable device using UWB pulses, the in-vehicle system including a control device (2) and an anchor (3) having an operating state in which UWB pulses can be received and a stopped state in which UWB pulses cannot be received, the method including: the control device acquiring a reference time and device oscillator error information, which is information regarding an error of a device oscillator, which is an oscillator possessed by the portable device, by communicating with the portable device; the control device generating communication setting data based on the reference time information; the control device transmitting the communication setting data to the anchor; acquiring anchor oscillator error information, which is error information of an anchor oscillator (36), which is an oscillator possessed by the anchor; and determining a transition timing, which is the timing when the anchor enters the standby state, or the duration of the standby state, based on the communication setting data, the device oscillator error information, and the anchor oscillator error information.

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