JP2020112418A - Position estimation system for vehicle, and position estimation device for vehicle - Google Patents

Abstract

To provide a position estimation system for a vehicle and a position estimation device for the vehicle capable of estimating a terminal position precisely while suppressing an increase in price.SOLUTION: A vehicle-side device transmits a radio signal in sequence from LF transmission antennas 32 disposed at plural places of a vehicle. A portable terminal returns a response signal for indicating reception strength of a signal each time when receiving the signal from the vehicle. A response acquisition part F2 of the vehicle-side device acquires reception strength for each of the LF transmission antennas 32 on the basis of a response signal from the portable terminal. An area location part F3 locates a candidate area in which a portable terminal 2 can exist on the basis of reception strength for each antenna. A position estimation part F4 calculates an error evaluation value for a candidate point positioned within the candidate area in a search area and determines a terminal position.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a technique of estimating a relative position of a communication device (hereinafter, a mobile terminal) carried by a user with respect to a vehicle by using radio waves.

Conventionally, three or more reference stations with known positions wirelessly communicate with mobile terminals such as smartphones to specify the distance from each reference station to the mobile terminal, and estimate the position of the mobile terminal based on the distance information from each reference station. A method has been proposed (for example, Patent Document 1). As a method for specifying the distance from the reference station to the mobile terminal, a method using a radio wave propagation time (in other words, a flight time), a method using a received signal strength (RSS), and the like have been proposed.

Hereinafter, for the sake of convenience, the method of positioning using the reception intensity is also referred to as the reception intensity method. In the reception strength method, the signal radiated from the antenna is considered to spread uniformly in all directions (that is, concentrically spherical), and the reception strength information is converted into distance information. Specifically, the reception strength is converted into the distance by using a model formula in which the reception strength is attenuated in inverse proportion to the cube or the square of the distance. As a positioning method using the propagation time of radio waves (so-called arrival time method), there are TOA (Time Of Arrival) method, TDOA (Time Difference Of Arrival) method, and the like.

JP, 2017-32486, A

In the arrival time method, the measurement error of the propagation time of the radio wave has a great influence on the estimation accuracy of the distance and the position. Specifically, the observation distance shifts by 30 cm even if the propagation time shifts by 1 nanosecond. Therefore, the arrival time method requires a device and a mechanism for accurately measuring the propagation time of a radio wave, and the cost is relatively high.

On the other hand, since the determination of the reception intensity can be realized using an inexpensive element/circuit, the reception intensity method can be realized relatively inexpensively. However, the reception intensity is affected not only by the propagation distance of the signal but also by various factors such as the metal body existing around the antenna and the directivity of the antenna. Therefore, even if the reception intensity is low, the mobile terminal does not always exist at a place away from the antenna. Therefore, the reception strength method has a large positioning error.

As one possible configuration for improving the positioning accuracy of the reception strength method, for example, the following is conceivable. That is, a plurality of terminal position candidate points are set within the search range, and data (hereinafter, intensity distribution map) in which the reception intensity at each candidate point is mapped by a test or the like is prepared in advance. The position estimation device converts the reception intensity into the observation distance using the intensity distribution map. Then, for each combination of the candidate point and the reference station, the sum of squares of the residuals of the observation distance and the estimated distance is calculated, and the candidate point having the smallest residual sum of squares is adopted as the position of the mobile terminal. The estimated distance refers to the straight line distance from the candidate point to the reference station.

Such a method corresponds to a method of searching for an optimum solution by brute force. Therefore, hereinafter, the above method is also referred to as a brute force search method.

In the brute force search method, it is necessary to calculate the residual sum of squares for each of a plurality of candidate points set within the search range. In order to increase the accuracy of estimating the position of the mobile terminal, it is necessary to reduce the setting interval of candidate points and increase the number of candidate points within the search range. Therefore, in the brute force search method, the calculation amount increases if the position estimation accuracy is increased.

Of course, the calculation load for position estimation does not pose a problem if a relatively high-performance processor is used. However, in vehicle electronic devices, it is difficult to use a high-performance processor as a computer used in an office or a home from the viewpoint of environmental resistance such as vibration resistance and heat resistance, and cost. That is, it is preferable that the vehicle position estimating device can estimate the position in a relatively short time without using a high-performance processor. The search range for the vehicle position estimation device is, for example, the entire vehicle interior or a three-dimensional space within 1 m from the side surface of the vehicle.

The present disclosure has been made based on this situation, and an object of the present disclosure is to provide a vehicle position estimation system capable of estimating a terminal position with higher accuracy while suppressing an increase in price, and a vehicle position estimation system. It is to provide a position estimation device.

A vehicle position estimation system for achieving the object is a vehicle position estimation system for a vehicle, in which a mobile terminal (2) carried by a vehicle user and a vehicle-side device (3) used in the vehicle perform wireless communication. In a vehicle position estimation system (1) for estimating a terminal position which is a position of a mobile terminal, a search range which is a range for setting a candidate point as a candidate for the terminal position is preset with a vehicle as a reference, The vehicle-side device includes a plurality of vehicle-side antennas (32, 32a to 32d) that transmit wireless signals to the mobile terminal, and the mobile terminal receives the signal from the vehicle-side antenna by the mobile-side receiving unit ( 22) and an intensity determination unit (221) that determines the reception intensity that is the intensity of the signal received by the mobile reception unit, and the vehicle-side device or the mobile terminal is determined by the intensity determination unit. Based on the intensity observation value that is the reception intensity of the signal transmitted from each vehicle-side antenna and the corresponding area that is preset for each vehicle-side antenna, the candidate area that is the area where the mobile terminal can exist is determined. An error evaluation value indicating the degree of deviation between the candidate point and the true terminal position is calculated for each candidate point based on the area specifying unit (F3) to be specified and the intensity observation value for each vehicle-side antenna, and the error evaluation is performed. A position estimation unit (F4) that employs, as a terminal position, a candidate point having the smallest value or a candidate point having an error evaluation value that is equal to or less than a predetermined allowable threshold, and the position estimation unit includes an area within the search range. It is configured to specify the terminal position by calculating an error evaluation value for candidate points existing in the candidate area specified by the specifying unit.

According to the above configuration, it is not necessary to calculate the error evaluation value for the candidate points existing in the area other than the candidate area specified by the area specifying unit among all the candidate points in the search range. Therefore, the calculation amount of the position estimation unit can be suppressed. Since the amount of calculation can be suppressed, the need for using a high-performance processor or the like is weakened. Therefore, the price of the system can be suppressed. Further, the above configuration estimates the terminal position based on the reception strength. Therefore, there is no need for a device and a mechanism for accurately measuring the propagation time of radio waves. Therefore, it can be realized at a lower cost than a system that performs positioning by the arrival time method.

Further, in the above configuration, the terminal position is specified based on the error evaluation value for each candidate point. With such a configuration, the positioning accuracy can be improved by reducing the setting interval of the candidate points. That is, according to the above configuration, it is possible to estimate the terminal position with higher accuracy while suppressing an increase in price.

Further, a vehicle position estimating device for achieving the above object is a vehicle position estimating a terminal position which is a position of the portable terminal with respect to the vehicle by performing wireless communication with a portable terminal carried by a user of the vehicle. In the estimation device, a search range, which is a range for setting candidate points as terminal position candidates, is preset with the vehicle as a reference, and receives the wireless signal transmitted from the mobile terminal and receives the wireless signal. A plurality of vehicle-side receivers (34, 34a to 34d) configured to be able to detect the reception intensity of the vehicle, intensity observation values that are reception intensities of the vehicle-side receivers, and preset for each vehicle-side receiver The area specifying unit (F3) that specifies a candidate area, which is an area in which the mobile terminal may exist, based on the corresponding area that has been set, and the strength observation value at each vehicle-side receiver, for each candidate point. , Calculating an error evaluation value indicating the degree of deviation between the candidate point and the true terminal position, and adopting the candidate point having the smallest error evaluation value or the candidate point having the error evaluation value equal to or less than a predetermined allowable threshold as the terminal position. The position estimation unit (F4) for performing the terminal position calculation by calculating the error evaluation value for the candidate points existing in the candidate area identified by the area identification unit within the search range. Is configured to identify.

The above vehicle position estimation device and the above vehicle position estimation system differ depending on whether the mobile terminal has the strength determination unit or the vehicle side device, but the other configurations are the same. is there. That is, the vehicle position estimation device estimates the position of the mobile terminal by the same procedure as the vehicle position estimation system. Therefore, the same effect as that of the vehicle position estimation system described above is achieved.

It should be noted that the reference numerals in parentheses described in the claims indicate the correspondence with the specific means described in the embodiments described below as one aspect, and limit the technical scope of the present disclosure. is not.

It is a block diagram showing the whole composition of position estimating system 1 for vehicles. 3 is a block diagram showing the configuration of the mobile terminal 2. FIG. It is a figure which shows an example of the attachment position and attachment posture of LF transmitting antenna 32a-32d. It is a functional block diagram which shows the structure of the information processing part 311. It is a conceptual diagram showing an example of the setting aspect of the corresponding area Cs. It is a conceptual diagram showing an example of the setting aspect of search range SR. It is a figure which shows the simulation result of the receiving intensity distribution of each LF transmitting antenna 32. It is a flow chart for explaining position estimating processing. It is a figure which shows the mutual relationship of the coordinate space distance r, the pitch angle (theta), the mounting position of the LF transmission antenna 32, and the position of a candidate point. It is a figure showing distance residual g. It is a figure which shows the modification of the setting mode of a candidate point. FIG. 13 is a diagram showing an overall configuration of a vehicle position estimation system 1 in Modification 7. 14 is a block diagram showing a configuration of an on-vehicle communication device 34 included in the vehicle side device 3 of Modification 7. FIG. It is a figure which shows the modification of search range SR.

Hereinafter, embodiments and the like of the present disclosure will be described with reference to the drawings. Note that, for convenience of description, in a plurality of embodiments, parts having the same functions as the parts shown in the drawings used in the above description are denoted by the same reference numerals, and the description thereof may be omitted. is there. For the parts denoted by the same reference numerals, the description in other embodiments can be referred to.

<Schematic configuration of vehicle position estimation system 1>
As shown in FIG. 1, the vehicle position estimation system 1 includes a mobile terminal 2 carried by a vehicle user and a vehicle-side device 3 mounted on the vehicle. The mobile terminal 2 is a mobile communication device (so-called mobile terminal) associated with the vehicle-side device 3, and is configured to function as a key of the vehicle, for example. Note that "carried by the user" is not limited to a state of being carried by the user, but also includes a state of not being carried by the user such as being left behind.

The mobile terminal 2 and the vehicle-side device 3 can communicate with each other wirelessly using radio waves in a predetermined frequency band. That is, when the mobile terminal 2 and the vehicle-side device 3 are within the communication range of each other, the other receives the signal transmitted by one by wireless communication.

Here, as an example, the portable terminal 2 has a function of receiving an LF (Low Frequency) band signal transmitted from the vehicle side device 3 and a vehicle side device as functions for performing wireless communication with the vehicle side device 3. 3 has a function of returning a signal of a predetermined frequency belonging to the UHF band. The vehicle-side device 3 has a function of transmitting a signal of a predetermined frequency belonging to the LF band and a function of receiving a signal of the UHF band transmitted from the mobile terminal 2, as functions for performing wireless communication with the mobile terminal 2. Have. Note that the LF band here refers to a frequency band of 300 kHz or less, and includes frequencies of 20 kHz to 30 kHz. The UHF band refers to 300 MHz to 3 GHz.

The LF band frequency (hereinafter, the first frequency) used for signal transmission from the vehicle-side device 3 to the mobile terminal 2 is, for example, 125 kHz or 134 kHz. Further, the UHF band frequency (hereinafter, the second frequency) used for signal transmission from the mobile terminal 2 to the vehicle side device 3 is, for example, 315 MHz or 920 MHz. Here, as an example, the configuration of each unit will be described by taking as an example the case where 134 kHz is adopted as the first frequency and 315 MHz is adopted as the second frequency.

The first frequency and the second frequency may be set to frequencies other than those mentioned above. The second frequency may be a frequency used in short-range wireless communication. The frequency used in the short-range wireless communication is, for example, a frequency belonging to the band from 2400 MHz to 2480 MHz (hereinafter, 2.4 GHz band). Further, the first frequency and the second frequency may belong to the same frequency band. The first frequency is preferably set to a frequency belonging to a frequency band of 20 kHz to 200 kHz from the viewpoint of ease of forming a communication area described later.

Hereinafter, for convenience, the LF band wireless signal transmitted by the vehicle-side device 3 is referred to as an LF signal, and the UHF band wireless signal transmitted by the mobile terminal 2 is also referred to as a UHF signal. The wireless signal emitted by the mobile terminal 2 is also referred to as an RF signal. RF is an abbreviation for Radio Frequency.

<Vehicle configuration>
First, the configuration of the vehicle will be described. The vehicle is, for example, a passenger car having a seating capacity of 5 people. Here, as an example, the vehicle includes a front seat and a rear seat, and a driver's seat (in other words, a steering wheel) is provided on the right side. The vehicle interior space located rearward of the vehicle with respect to the backrest of the rear seat is configured as a space (hereinafter referred to as a trunk area) that functions as a luggage compartment (in other words, a trunk room). The space for the rear seats of the vehicle communicates with the luggage compartment via the upper part of the backrest for the rear seats.

In the present specification, for convenience, a space in the vehicle interior space that is located in front of the vehicle with respect to the backrest of the front seat is referred to as a front area. The front area also includes the vehicle interior space above the instrument panel. Further, a vehicle interior space that is behind the vehicle in front of the backrest of the front seat and in front of the vehicle in front of the backrest of the rear seat is also referred to as a rear area.

Of course, the vehicle may be a vehicle having a structure other than the examples described above. For example, the vehicle may be a vehicle having a driver's seat on the left side. Alternatively, the vehicle may not have a rear seat. In addition, the vehicle may be a vehicle having a luggage compartment that is independent of the vehicle interior space. The vehicle may be provided with a plurality of rows of rear seats. The vehicle may be a lorry such as a truck. Further, the vehicle may be a taxi or a camper.

The body of the vehicle is realized by using a material such as a resin that allows radio waves to pass therethrough. The body here includes, for example, a frame portion that constitutes the body main body portion such as a side sill and a center pillar, and a body panel that provides the external shape of the vehicle. Body panels include side body panels, roof panels, rear end panels, bonnet panels, door panels, and the like. The radio wave here refers to a radio wave having a first frequency or a second frequency, that is, a radio wave in a frequency band used for wireless communication between the vehicle-side device 3 and the mobile terminal 2. Further, the material that allows radio waves to pass means a material whose signal attenuation (in other words, loss) is within 3 dB. At least the door panel of the vehicle may be made of resin, and the body portion may be made of metal.

<Schematic configuration of mobile terminal 2>
Here, the mobile terminal 2 will be described with reference to FIG. As shown in FIG. 2, the mobile terminal 2 includes an LF reception antenna 21, an LF reception unit 22, a mobile-side control unit 23, a UHF transmission unit 24, and a UHF transmission antenna 25. The mobile terminal 2 may have the following configuration, and the mobile terminal 2 may be a dedicated terminal for a PEPS system, a smartphone, a wearable device, a tablet terminal, a portable music player, a portable terminal. It may be a game machine or the like.

The LF reception antenna 21 is an antenna that receives the LF signal transmitted from the LF transmission antenna 32 included in the vehicle side device 3. The LF receiving antenna 21 is a magnetic field type antenna, and is configured as, for example, a loop antenna or a bar antenna. The LF receiving antenna 21 is connected to the LF receiving unit 22, converts the received radio wave into an electric signal and outputs the electric signal to the LF receiving unit 22.

The LF receiving unit 22 is configured to receive the LF signal transmitted from the vehicle side device 3 via the LF receiving antenna 21. The LF reception unit 22 is electrically connected to the LF reception antenna 21, and receives the electrical LF signal received by the LF reception antenna 21. The LF receiving unit 22 extracts data included in the received signal by performing predetermined processing such as analog-digital conversion, demodulation, and decoding on the signal input from the LF receiving antenna 21. Then, the extracted data is provided to the mobile-side controller 23. The LF reception unit 22 corresponds to the mobile reception unit.

Further, the LF reception unit 22 of the present embodiment includes a reception strength determination unit 221 that measures the strength of the signal received by the LF reception antenna 21 (hereinafter, reception strength). Here, the LF receiving antenna 21 is configured as a magnetic field type antenna. Therefore, the reception strength indicates the magnetic field strength of the signal received by the LF reception antenna 21.

As a method of measuring the reception intensity, various methods such as a method of calculating the reception intensity from the current flowing through the LF reception antenna 21 can be used. The reception strength determination unit 221 can be realized by various circuit configurations. When the LF receiving antennas 21 are multi-axis coil antennas arranged so as to be orthogonal to each other, the magnitude of the magnetic field strength vector obtained by combining the magnetic field strengths in each axial direction is adopted as the receiving strength. It may be configured. The magnetic field strength for each axial direction may be specified, for example, from the current amount and the current direction of the coil antenna of each axis. The reception intensity detected by the reception intensity determination unit 221 is sequentially provided to the mobile-side control unit 23 in association with the reception data.

The mobile-side control unit 23 is configured to control the operation of the mobile terminal 2, and is realized by using, for example, a dedicated IC. The mobile-side control unit 23 may be realized by using a computer including a CPU, a RAM, a ROM, and the like. In addition, the mobile-side control unit 23 may be realized using an MPU or GPU. The mobile-side control unit 23 may be realized by using an FPGA (field-programmable gate array) or an ASIC (application specific integrated circuit).

When the reception data is input from the LF reception unit 22, the mobile-side control unit 23 generates a baseband signal corresponding to a response signal corresponding to this reception data. The response signal includes information indicating the reception strength of the reception data determined by the reception strength determination unit 221 (hereinafter, reception strength information). When the mobile-side control unit 23 generates a baseband signal as a response signal including reception strength information, the mobile-side control unit 23 outputs the baseband signal to the UHF transmission unit 24. The baseband signal as a response signal output from the mobile-side controller 23 to the UHF transmitter 24 is subjected to predetermined modulation processing by the UHF transmitter 24 and transmitted as a radio signal.

The UHF transmission unit 24 is electrically connected to the mobile-side control unit 23 and the UHF transmission antenna 25. The UHF transmission unit 24 performs predetermined processing such as modulation processing and digital-analog conversion on the baseband signal input from the mobile-side control unit 23, and outputs the baseband signal to the UHF transmission antenna 25. The UHF transmitting antenna 25 is a UHF transmitting antenna used for transmitting signals in the UHF band. The UHF transmitting antenna 25 converts the electric signal input from the UHF transmitting unit 24 into a radio wave in the UHF band and radiates it into space.

With the above configuration, the mobile terminal 2 generates and returns a response signal each time the LF signal is received. Therefore, as will be described later, when the LF signals are sequentially transmitted from the plurality of LF transmission antennas 32, the mobile terminal 2 receives the LF signals of different transmission sources from the mobile terminal 2. A response signal indicating the reception intensity is returned. Hereinafter, for convenience, the reception strength of the LF signal transmitted from each of the plurality of LF transmission antennas 32 at the mobile terminal 2 will be simply described as the reception strength for each antenna.

<Schematic configuration of vehicle-side device 3>
The vehicle-side device 3 performs wireless communication using radio waves in a predetermined frequency band with the mobile terminal 2 to perform predetermined vehicle control according to the position of the mobile terminal 2 (hereinafter, also referred to as terminal position). A passive entry/passive start system (hereinafter, PEPS system) is realized.

For example, when the vehicle-side device 3 can confirm that the mobile terminal 2 is present within the operation area preset for the vehicle, the vehicle-side device 3 locks the door based on a user operation on a door button described later. And control such as unlocking. In addition, when the vehicle-side device 3 can confirm that the mobile terminal 2 is present in the vehicle compartment by wireless communication with the mobile terminal 2, the vehicle-side device 3 performs engine start control based on a user operation on a start button described later. To execute.

The operation area is an area for the vehicle-side device 3 to execute predetermined vehicle control such as locking and unlocking of the door based on the presence of the mobile terminal 2 in the area. For example, the vicinity of the door for the driver's seat, the door for the passenger seat, and the vicinity of the trunk door are set as the operation areas. The vicinity of the door means a range within a predetermined working distance from the outer door handle. The outer door handle refers to a grip member provided on the outer surface of the door for opening and closing the door. In the present embodiment, as an example, an area outside the vehicle compartment that is within the working distance from the outer door handle for the driver's seat and the outer door handle for the passenger seat is set as the working area. The working distance that defines the size of the working area is 0.7 m, for example. The working distance may be 1 m or 1.5 m.

As shown in FIG. 1, the vehicle-side device 3 includes a smart ECU 31, a plurality of LF transmission antennas 32a to 32d, and at least one UHF receiver 33. The LF transmission antennas 32a to 32d correspond to vehicle-side antennas.

The LF transmission antennas 32a to 32d are all antennas that transmit LF signals. When the description is made without distinguishing each of the LF transmission antennas 32a to 32d, the LF transmission antenna 32 is also described. The LF transmission antenna 32 is a magnetic field type antenna. As the LF transmission antenna 32, for example, a uniaxial loop antenna, a bar antenna, or the like can be adopted. Here, as an example, it is assumed that the LF transmission antenna 32 is realized by using a bar antenna. The loop antenna forms a magnetic field in a direction orthogonal to the loop surface. The bar antenna also forms a magnetic field in the axial direction of the core member. Further, the axial direction of the LF transmission antenna 32 hereinafter means the direction in which a magnetic field is generated in the magnetic field type antenna.

Here, an example of the arrangement of the LF transmission antennas 32a to 32d will be described with reference to FIG. As shown in FIG. 3, the LF transmission antenna 32a is arranged on the right side of the driver's seat of the vehicle. For example, the LF transmitting antenna 32a is built in near the inside door handle of the door for the driver's seat in a posture in which the axial direction is along the longitudinal direction of the vehicle. As another aspect, the LF transmission antenna 32a may be arranged on the right side surface portion of the body. For example, the LF transmission antenna 32a may be built in the outer door handle of the driver's seat door.

The LF transmission antenna 32b is arranged on the left side of the driver's seat of the vehicle. For example, the LF transmission antenna 32b is built in near the inner door handle of the passenger seat with the axial direction of the antenna aligned with the front-rear direction of the vehicle. Note that, as another aspect, the LF transmission antenna 32b may be arranged on the left side surface portion of the body. For example, the LF transmission antenna 32b may be built in the outside door handle of the passenger seat door.

The LF transmission antenna 32c is arranged in the front area of the vehicle interior. For example, the LF transmission antenna 32c is attached near the center console with the antenna axial direction extending along the vehicle width direction. The LF transmission antenna 32d is arranged in the rear area inside the vehicle. For example, the LF transmission antenna 32d is attached to a portion of the ceiling surface of the vehicle compartment located above the backrest portion of the rear seat in a posture in which the antenna axial direction is along the vehicle width direction.

Each LF transmission antenna 32 has an ellipsoidal directivity whose major axis is the axial direction. Therefore, the LF transmission antennas 32a to 32b transmit signals relatively stronger in the vehicle front-rear direction than in the vehicle height direction and the vehicle width direction. In addition, the LF transmission antennas 32c to 32d transmit signals relatively stronger in the vehicle width direction than in the vehicle height direction or the vehicle front-rear direction. The spheroid corresponds to a rotating body obtained by rotating an ellipse with its major axis as a rotation axis, and is also called an ellipsoid. The long sphere here mainly means an ellipsoid whose major axis is 1.1 times or more of its minor axis.

The broken line in FIG. 3 conceptually shows the directivity of each LF transmission antenna 32. The signal transmitted from each LF transmission antenna 32 is not limited to the area surrounded by the broken line, and propagates to the outside of the area surrounded by the broken line. Each of the LF transmission antennas 32 wirelessly transmits a signal input from an LF driver 312 described below with a predetermined transmission power. The transmission power at the LF transmission antenna 32 may be adjusted so as to form a desired communication area. Each LF transmission antenna 32 is configured such that the transmission signal reaches at least the entire area/most area of the vehicle interior.

It should be noted that the number, installation position, and mounting orientation of the LF transmission antennas 32 mounted on the vehicle can be changed as appropriate. The vehicle-side device 3 may be provided with an LF transmission antenna 32 having a communication area inside the trunk and an LF transmission antenna 32 having a communication area near the trunk door outside the passenger compartment in addition to the positions described above.

The UHF receiver 33 is configured to receive a response signal including reception intensity information, which is transmitted from the mobile terminal 2 using radio waves in the UHF band. The UHF receiver 33 includes a UHF receiving antenna (not shown), a demodulation circuit, and the like. The UHF receiving antenna is an antenna for receiving radio waves in the UHF band transmitted from the mobile terminal 2. The UHF receiver 33 extracts data included in the received signal by performing predetermined processing such as analog-digital conversion, demodulation, and decoding on the signal input from the UHF receiving antenna. Then, the extracted data is provided to the smart ECU 31.

The smart ECU 31 is configured to control the operation of each LF transmission antenna 32 and the UHF receiver 33. The smart ECU 31 includes an information processing unit 311 and an LF driver 312 as a finer configuration. The smart ECU 31 is electrically connected to the LF transmission antennas 32a to 32d, the UHF receiver 33, and the like.

The information processing unit 311 controls the operation of each LF transmission antenna 32 and the UHF receiver 33 using the data input from the UHF receiver 33, various sensors mounted on the vehicle, and the ECU, and A calculation process for estimating the position of the terminal 2 is executed. The information processing unit 311 includes, for example, a processor such as a CPU, a memory, an I/O, and a bus connecting these, and executes a control program stored in the memory to perform various types of processing related to the estimation of the position of the mobile terminal 2. The process of is executed. The execution of this control program by the processor corresponds to the execution of the method corresponding to the control program. This method corresponds to the terminal position estimation method.

The memory mentioned here is a non-transitory tangible storage medium that non-temporarily stores computer-readable programs and data. As the non-transitional physical storage medium, various storage media such as a semiconductor memory or a magnetic disk can be adopted. The memory stores data indicating the mounting positions of the LF transmission antennas 32a to 32d. The mounting position of each LF transmission antenna 32 is expressed as a point in a three-dimensional orthogonal coordinate system with an arbitrary point of the vehicle as a reference point (in other words, the origin). Here, as an example, it is assumed that the mounting position of the LF transmission antenna 32 is represented by a three-dimensional coordinate system including the X, Y, and Z axes with the center of the front wheel axle as the origin. The X axis is parallel to the vehicle width direction, and the vehicle right side is the positive direction. The Y axis is parallel to the front-rear direction of the vehicle, and the front of the vehicle is the positive direction. The Z-axis is an axis that is parallel to the vehicle height direction and has a positive direction above the vehicle. Of course, the mounting position of each LF transmission antenna 32 may be represented by polar coordinates as another aspect.

The information processing unit 311 may be realized by using an MPU or GPU instead of the CPU. Further, the information processing unit 311 may be realized by combining a plurality of types of arithmetic processing modules such as a CPU, MPU, and GPU. Further, the information processing unit 311 may be realized using an FPGA (field-programmable gate array) or an ASIC (application specific integrated circuit). Details of the functions provided by the information processing unit 311 will be described later.

The LF driver 312 is configured to transmit the LF signal from the LF transmission antennas 32a to 32d. The LF driver 312 is realized by using, for example, an IC. The LF driver 312 causes the LF transmission antennas 32a to 32d to sequentially transmit LF signals in accordance with a request from the transmission processing unit F1. Specifically, the LF driver 312 sequentially outputs the modulated signal to each LF transmission antenna 32 so that the transmission timings of the signals at each LF transmission antenna 32 do not overlap. This causes the respective LF transmission antennas 32 to sequentially transmit. By shifting the timing of transmitting radio waves from each LF transmitting antenna 32, it is possible to prevent a signal transmitted from a certain LF transmitting antenna 32 from interfering with a signal transmitted from another LF transmitting antenna 32.

<About the function of the information processing unit 311>
The information processing unit 311 is a functional block realized by the CPU executing a predetermined control program, as illustrated in FIG. 4, a transmission processing unit F1, a response acquisition unit F2, an area identification unit F3, and a position estimation unit F4. Equipped with. In addition, a corresponding area storage unit M1 using a nonvolatile storage medium and an intensity distribution storage unit M2 are provided.

As shown in FIG. 5, the corresponding area storage unit M1 is a storage device that stores data indicating the corresponding area Cs for each LF transmission antenna 32 within the search range SR. The search range SR here corresponds to the entire range in which the position of the mobile terminal 2 is searched, and specifically refers to a space for setting candidate points for the terminal position. Although the search range SR is shown in a plane in FIG. 5, it is actually set three-dimensionally so as to include the vehicle as shown in FIG. The area inside the one-dot chain line in FIGS. 5 and 6 corresponds to the search range SR.

In the present embodiment, a space within Dx from the left and right side surfaces of the vehicle, less than Dz in height, behind the front end portion, and within Dy from the rear end portion is set as the search range SR. Dx and Dy are set to 1 m, for example. Dz is set to 2 m, for example. When the size of the host vehicle is, for example, 2 m in vehicle width and 4 m in vehicle length, the search range SR has a length in the vehicle width direction of 6 m and a length in the vehicle front-rear direction of 5 m. Therefore, the volume of the search target installation space is 6 m×5 m×2 m=60 m ³ . The candidate points are set in the search range SR, for example, at intervals of 2 cm in the X-, Y-, and Z-axis directions.

The corresponding area Cs of a certain LF transmitting antenna 32 is a signal transmitted from another LF transmitting antenna 32 when the reception intensity of the signal transmitted from the LF transmitting antenna 32 in the search range SR is received by the mobile terminal 2. It is a space that is expected to be higher than the reception intensity of. FIG. 5A conceptually shows the corresponding area Cs of the LF transmission antenna 32a, and FIG. 5B conceptually shows the corresponding area Cs of the LF transmission antenna 32b. Further, (C) of FIG. 5 conceptually shows the corresponding area Cs of the LF transmission antenna 32c, and (D) conceptually shows the corresponding area Cs of the LF transmission antenna 32d. In FIG. 5, a region surrounded by a chain double-dashed line (in other words, a region where a dot pattern is hatched) indicates the corresponding area Cs. Although the corresponding area is shown in a plan view in FIG. 5, it is actually set three-dimensionally like the search range SR.

The data indicating the corresponding area Cs for each LF transmitting antenna 32 may be represented by the coordinates of the same three-dimensional coordinate system as the mounting position of the LF transmitting antenna 32. The corresponding area Cs of each LF transmitting antenna 32 may have a portion overlapping with the corresponding area Cs of another LF transmitting antenna 32. Each corresponding area Cs corresponds to a sub area formed by dividing the search range SR.

The intensity distribution storage unit M2 is a storage device that stores data (intensity distribution map) indicating a distribution of reception intensity for each antenna within the search range SR. The intensity distribution map may be generated by actually measuring/simulating the reception intensity for each antenna at each candidate point. The intensity distribution map corresponds to the intensity distribution model.

FIG. 7A conceptually shows the reception intensity distribution of the LF transmission antenna 32a by contour lines, and FIG. 7B conceptually shows the reception intensity distribution of the LF transmission antenna 32b by contour lines. ing. Further, (C) of FIG. 7 conceptually shows the reception intensity distribution of the LF transmission antenna 32c with contour lines, and (D) conceptually shows the reception intensity distribution of the LF transmission antenna 32d with contour lines. Is shown in. The contour line here is a line formed by points having the same reception intensity. The contour line can be restated as a contour line. FIG. 7 shows a mode in which the interval between contour lines is set to 7.5 dBμV/m for simplification of the drawing.

Strictly speaking, FIG. 7 shows a result of simulating a magnetic field strength distribution of a signal wirelessly transmitted from each LF transmission antenna 32. Although the magnetic field strength of the transmission signal and the reception strength are different physical quantities, they have a proportional relationship due to the reversibility of transmission and reception, and can be adopted as an alternative characteristic.

Although FIG. 7 shows the reception intensity distribution of each LF transmission antenna 32 in a two-dimensional plane, the reception intensity of each LF transmission antenna 32 is three-dimensionally distributed. The contour line and the contour line described above correspond to one cross section of a curved surface (hereinafter, contour plane) formed by points having the same reception intensity. The contour surface can be restated as a constant strength surface.

The intensity distribution map only needs to show the reception intensity for each antenna at each candidate point, and various formats such as a map format and a table format can be adopted as the expression format. The intensity distribution map held in the intensity distribution storage unit M2 is referred to by the position estimation unit F4.

The transmission processing unit F1 is configured to execute processing relating to the transmission of the LF signal. The transmission processing unit F1 requests the LF driver 312 to transmit LF signals in order from the LF transmission antennas 32a to 32d at a predetermined timing. Hereinafter, for convenience, transmitting the LF signals from each of the LF transmission antennas 32a to 32d in a predetermined order will be referred to as LF transmission processing in order.

For example, the transmission processing unit F1 sequentially requests the LF driver 312 to execute the LF transmission process when the door button provided on the outer door handle of the vehicle door is operated while the vehicle is parked. To do. In addition, the transmission processing unit F1 is configured to sequentially request the LF driver 312 to execute the LF transmission process when the host vehicle is parked and the start button is operated as a trigger. Good. The start button is a push switch for requesting the start of the traveling drive source of the vehicle, and is provided near the driver's seat (for example, the instrument panel) in the vehicle compartment.

Whether or not the host vehicle is parked may be determined by the information processing unit 311 based on the vehicle speed detected by the vehicle speed sensor, the shift position detected by the shift position sensor, the signal of the parking brake switch, and the like. Various determination algorithms can be adopted as a method of determining whether or not the host vehicle is parked. The information processing unit 311 may determine that the door button is operated based on a signal from the door button.

The response acquisition unit F2 acquires the response signal including the reception intensity, which is received from the mobile terminal 2 by the UHF receiver 33. Each time the mobile terminal 2 receives the LF signals sequentially transmitted from the LF transmission antennas 32a to 32d, it returns a response signal including the reception intensity. Therefore, the smart ECU 31 (mainly the response acquisition unit F2) can uniquely identify the LF transmission antenna 32 that has transmitted the LF signal to which the mobile terminal 2 responded, from the timing at which the response signal to the LF signal was received. In other words, the response acquisition unit F2 determines which LF transmission antenna 32 the mobile terminal 2 has responded to, based on the relationship between the signal transmission timing of each LF signal and the reception timing of the response signal. Can be specified. As a result, the response acquisition unit F2 acquires the reception intensity of the LF signal transmitted from each LF transmission antenna 32 at the mobile terminal 2. The response acquisition unit F2 outputs data indicating the reception intensity for each antenna to the position estimation unit F4.

If the response signal includes a code for authentication, authentication is performed using this code, and according to the position of the mobile terminal 2 estimated by the position estimation unit F4 and the presence/absence of authentication, It suffices to lock and unlock the door of the vehicle, permit starting of a vehicle drive source (for example, an engine), and the like. As an authentication method for the mobile terminal 2, various methods such as a challenge response method can be adopted.

The area identification unit F3 compares the reception intensities of the respective antennas and identifies the LF transmission antenna 32 (hereinafter, the nearest antenna) having the highest reception intensity in the mobile terminal 2 among the plurality of LF transmission antennas 32. Then, it is determined that the mobile terminal 2 exists within the corresponding area Cs of the nearest antenna. That is, the corresponding area Cs of the nearest antenna is set as a candidate area where the mobile terminal can exist. Such an area specifying unit F3 corresponds to a configuration that specifies (in other words, narrows down) an area in which the mobile terminal 2 may exist in the search range SR. Further, according to another aspect, the configuration corresponds to a configuration in which an area where the mobile terminal 2 is not likely to exist/is sufficiently low in the search range SR is excluded from the search target.

The area specifying unit F3 obtains the highest reception intensity when the difference between the highest reception intensity and the second highest reception intensity is less than a predetermined integration threshold as a result of comparing the reception intensities for each antenna. Even if it is configured to set a range in which the corresponding area Cs of the LF transmitting antenna 32 that has been obtained and the corresponding area Cs of the LF transmitting antenna 32 that has the second highest reception intensity are integrated as the candidate area. good. In addition, the area specifying unit F3 may be configured to include the corresponding area Cs of the LF transmission antenna 32, in which the reception intensity with the difference from the highest reception intensity being less than the predetermined integration threshold value, is included in the candidate area. good. According to the above configuration, it is possible to reduce the risk of the true terminal position leaking from the candidate area when there is no significant difference in the reception intensity for each antenna. The integrated threshold may be set to, for example, 3 dB.

The position estimation unit F4 estimates the position of the mobile terminal 2 using the reception intensity for each antenna acquired by the response acquisition unit F2. The operation of the position estimation unit F4 will be described later.

<About position estimation processing>
Next, a process (hereinafter, position estimation related process) related to the estimation of the terminal position in the smart ECU 31 will be described with reference to the flowchart shown in FIG. The flowchart of FIG. 8 may be executed when a predetermined position estimation condition is satisfied, such as when the door button or the start button is pressed. The position estimation process may be executed periodically (for example, every 200 milliseconds). In the present embodiment, as an example, the position estimation process includes steps S101 to S109.

First, in step S101, the transmission processing unit F1 cooperates with the LF driver 312 to sequentially execute the LF transmission processing. That is, the transmission processing unit F1 requests the LF driver 312 to sequentially transmit LF signals from the LF transmission antennas 32a to 32d. Accordingly, the LF driver 312 causes the LF transmission antennas 32a to 32d to sequentially transmit the LF signal. Each time the mobile terminal 2 receives the LF signals that are sequentially transmitted, it returns a response signal indicating the reception intensity.

In step S102, the response acquisition unit F2 cooperates with the UHF receiver 33 to acquire the observation values (hereinafter, also referred to as intensity observation values) Bo1 to Bo4 of the reception intensity for each antenna. The intensity observation value Bo1 represents the reception intensity of the LF signal transmitted from the LF transmission antenna 32a at the mobile terminal 2, and the intensity observation value Bo2 is the reception of the LF signal transmitted from the LF transmission antenna 32b at the mobile terminal 2. Represents strength. The intensity observation value Bo3 represents the reception intensity of the LF signal transmitted from the LF transmission antenna 32c at the mobile terminal 2, and the intensity observation value Bo4 is the reception of the LF signal transmitted from the LF transmission antenna 32d at the mobile terminal 2. Represents strength. In the intensity observation values Bo1 to Bo4, when the transmission sources are not distinguished, the intensity observation values Bo are also described. The "o" of "Bo" is the meaning of Observation.

If no response signal can be received, or if the number of LF transmission antennas 32 that can receive the response signal is less than 3, this flow may be stopped. When this flow is stopped, for example, it may be executed again from step S101 at a timing when a predetermined retry time (for example, 200 milliseconds) has elapsed from the stop point.

In step S103, the area identifying unit F3 determines the candidates based on the intensity observation values Bo1 to Bo4 for each antenna acquired in step S102 and the corresponding area Cs for each antenna stored in the corresponding area storage unit M1. Determine the area. For example, when the intensity observation value Bo1 of the LF transmission antenna 32a is the highest among the intensity observation values Bo of each antenna, the corresponding area Cs of the LF transmission antenna 32a is set as the candidate area.

In step S104, the position estimation unit F4 sets any one candidate point existing in the candidate area determined by the area identification unit F3 in the previous step S103 as a target candidate point, and proceeds to step S105.

In step S105, the intensity distribution map stored in the intensity distribution storage unit M2 is referred to, and the assumed value (hereinafter, intensity estimated value) Be1 to Be4 of the reception intensity for each antenna at the target candidate point is acquired. The intensity estimation value Be1 represents the reception intensity of the LF signal transmitted from the LF transmission antenna 32a at the mobile terminal 2, and the intensity estimation value Be2 is the reception of the LF signal transmitted from the LF transmission antenna 32b at the mobile terminal 2. Represents strength. The intensity estimation value Be3 represents the reception intensity of the LF signal transmitted from the LF transmission antenna 32c at the mobile terminal 2, and the intensity estimation value Be4 is the reception of the LF signal transmitted from the LF transmission antenna 32d at the mobile terminal 2. Represents strength. In the strength estimation values Be1 to Be4, when the transmission sources are not distinguished, the strength estimation value Be is also described. "E" of "Be" means "estimate".

ステップＳ１０６での処理が完了すると、ステップＳ１０７に移る。ステップＳ１０７では、候補エリア内に位置する全ての候補点について残差平方和ＲＳＳを算出したか否かを判定する。候補エリア内の全ての候補点について残差平方和ＲＳＳを算出している場合にはステップＳ１０７を肯定判定してステップＳ１０９を実行する。一方、候補エリアの中に、まだ残差平方和を算出していない候補点が残っている場合にはステップＳ１０７を否定判定してステップＳ１０８を実行する。 In step S106, the sum of squares of residuals (hereinafter, sum of squares of residuals) RSS about the reception strength for each antenna at the target candidate point is calculated by the following equations 1 to 5. The residual sum of squares RSS is a parameter indicating the degree of deviation (in other words, the degree of deviation) between the candidate point and the true terminal position. That is, the residual sum of squares RSS corresponds to the error evaluation value. The error index value may be the sum of absolute values of the residuals.

When the process in step S106 is completed, the process proceeds to step S107. In step S107, it is determined whether the residual sum of squares RSS has been calculated for all candidate points located in the candidate area. When the residual sum of squares RSS has been calculated for all candidate points in the candidate area, an affirmative decision is made in step S107 and step S109 is executed. On the other hand, if there remains a candidate point for which the residual sum of squares has not been calculated in the candidate area, a negative determination is made in step S107 and step S108 is executed.

In step S108, an arbitrary candidate point that belongs to the candidate area and has not yet calculated the residual sum of squares RSS is set as a target candidate point, and step S105 is executed. For example, in step S108, candidate points adjacent in the X-axis direction from the current target candidate point are set as target candidate points. The order of setting the target candidate points (in other words, the search direction) may be appropriately designed.

In step S109, of all the candidate points existing in the candidate area, the candidate point having the smallest residual sum of squares RSS is adopted as the terminal position, and the present flow ends. The residual sum of squares RSS is a parameter that comprehensively evaluates the magnitude of the residual corresponding to each of the plurality of LF transmission antennas. The candidate point having the smallest residual sum of squares RSS can be expected to be the candidate point closest to the true terminal position.

As the processing after step S109, for example, the position estimation unit F4 determines whether the terminal position adopted in step S109 corresponds to the operating area or the vehicle interior. If the terminal position falls within the operating area, the door is unlocked or locked. Further, when the terminal position corresponds to the inside of the vehicle, the traveling drive source is started.

<Effect of this embodiment>
Here, three comparative configurations, that is, the first, second, and third comparative configurations are introduced, and effects of the present embodiment will be described.

なお、上記式における（Ｘ_ｐ，Ｙ_ｐ，Ｚ_ｐ）は候補点の座標を表す。（Ｘ_ｉ，Ｙ_ｉ，Ｚ_ｉ）は、ＬＦ送信アンテナ３２ａ〜３２ｄの位置を表す。Δｔ_ｉは、ＬＦ送信アンテナ３２から送信されたＬＦ信号の伝搬時間を表す。ｉ＝１〜４は、ＬＦ送信アンテナ３２ａ〜３２ｄに順に対応する。例えば、（Ｘ_１，Ｙ_１，Ｚ_１）はＬＦ送信アンテナ３２ａの設置位置を示し、Δｔ_１は、ＬＦ送信アンテナ３２ａから送信されたＬＦ信号の伝搬時間を示す。ｉの最大値は、車両側装置３が備えるＬＦ送信アンテナ３２の数に相当する。 The first comparison configuration uses TOA (Time Of Arrival), TDOA (Time Difference Of Arrival), and other radio wave propagation time (in other words, flight time) Δt and radio wave propagation speed C as a distance as an observation value. Is calculated, and the deviation degree (that is, the residual) between the candidate point and the true terminal position is evaluated by the concept of the distance. In the first comparison configuration, the residual sum of squares RSS is expressed by Equation 6 below.

Note that (X _p , Y _p , Z _p ) in the above formula represents the coordinates of the candidate point. (X _i , Y _i , Z _i ) represents the positions of the LF transmission antennas 32a to 32d. Δt _i represents the propagation time of the LF signal transmitted from the LF transmission antenna 32. i=1 to 4 correspond to the LF transmission antennas 32a to 32d in order. For example, (X ₁ , Y ₁ , Z ₁ ) indicates the installation position of the LF transmission antenna 32a, and Δt ₁ indicates the propagation time of the LF signal transmitted from the LF transmission antenna 32a. The maximum value of i corresponds to the number of LF transmission antennas 32 included in the vehicle side device 3.

According to the first comparison configuration described above, the terminal position can be estimated approximately by iterative calculation about 3 to 4 times using the Newton method or the like. However, in the first comparison configuration, the propagation time Δt of the radio wave is used for estimating the distance. Since the propagation speed C of the radio wave is very high, the observation distance is deviated by 30 cm even if the propagation time Δt is shifted by 1 nanosecond. That is, in the first comparison configuration, it is necessary to be able to measure the propagation time Δt of the radio wave (speed of light) with extremely high accuracy. Since the highly accurate time measuring function requires expensive elements, the first comparison configuration relatively increases the cost.

第２比較構成においても、第１比較構成と同様に、ニュートン法等を用いて３〜４回程度の反復計算によって近似的に端末位置を推定できる。また、電波の信号強度は電波の伝搬時間Δｔを計測するよりも安価な素子／回路を用いて検出可能であるため、第２比較構成によれば、第１比較構成よりもシステムのコストを抑制できる。 In the second comparison configuration, the signal radiated from the LF transmission antenna 32 is considered to spread evenly (that is, concentrically spherically) in all directions, and the LF transmission antenna 32 is extracted from the candidate point based on the intensity observation value Bo. This is a configuration in which the distance to is calculated and the residual is evaluated. In the second comparison configuration, the residual sum of squares RSS is calculated by the following equation 7. Note that D(Bo) in the equation is a function for converting the intensity observation value Bo into a distance. For example, in the near field of the antenna, the signal strength is inversely proportional to the cube of the distance. That is, it has a relationship of B=κ/d ³ . Therefore, D(Bo)=(κ/Bo)^(1/3) can be obtained. Note that κ is a constant.

Also in the second comparison configuration, similarly to the first comparison configuration, the terminal position can be approximately estimated by iterative calculation about 3 to 4 times using the Newton method or the like. In addition, since the signal strength of the radio wave can be detected by using an element/circuit that is cheaper than measuring the propagation time Δt of the radio wave, the second comparison configuration can reduce the system cost more than the first comparison configuration. it can.

However, the signal radiated from the LF transmission antenna 32 does not spread evenly (that is, concentrically) in all directions. For example, the signal radiated from the LF transmission antenna 32 spreads in an oblong shape. Further, even if the LF transmission antenna 32 is an omnidirectional antenna, the signal from the LF transmission antenna 32 is concentrically spherical because it is affected by reflection and diffraction on the body of the vehicle and the structure inside the vehicle interior. Does not spread. For example, when a metal body such as a center pillar or a rear pillar exists near the LF transmission antenna 32, the contour line (actually a contour surface) of the intensity distribution may be distorted by the metal body. Therefore, the intensity observation value Bo does not always correspond to the straight line distance between two points. Even near the LF transmission antenna 32, a portion where the reception intensity becomes relatively small may occur due to the influence of the structure and directivity. This tendency is particularly strong on the back side of the metal plate. Therefore, in the position estimation by the method of the second comparison configuration, an error of several tens of centimeters or more may actually occur.

On the other hand, in the configuration of the present embodiment, the residual value and the residual sum of squares RSS are evaluated using the estimated value Be of the reception intensity for each candidate point that is preset by simulation or the like. That is, the residual is calculated using an estimated value that takes into consideration the influence of the vehicle structure and the like. Therefore, the terminal position can be estimated more accurately than in the second comparison configuration. In other words, it can be said that the configuration of the present embodiment is suitable when the vehicle-side antenna is configured using an antenna having a non-spherical (for example, elliptical) radiation characteristic. Further, the configuration of the present embodiment can be said to be suitable when the reception intensity of the signal transmitted from the vehicle-side antenna is distributed in a non-spherical shape due to the influence of the vehicle body or vehicle interior structure.

The third comparison configuration is a configuration for calculating the residual by the same method as that of this embodiment. However, the third comparison configuration calculates the residual sum of squares RSS for all candidate points in the search range SR, and then employs the candidate point having the smallest residual sum of squares RSS as the terminal position.

In such a third comparison configuration, the residual sum of squares RSS needs to be calculated for all candidate points in the search range SR in one position estimation process, so the amount of calculation in the position estimation unit F4 is performed. Becomes huge. For example, if candidate points are set at 2 cm intervals in the X-axis direction, the Y-axis direction, and the Z-axis direction in a space of 6 m×5 m×2 m=60 m ³ , the total number of candidate points becomes 7.5 million. Therefore, in the third comparison configuration, the calculation of the residual sum of squares RSS must be repeated 7.5 million times in one position estimation process.

According to the configuration of the present embodiment with respect to such a third comparison configuration, the area specifying unit F3 determines the candidate areas, and thus the candidate points for which the residual sum of squares RSS is calculated are limited. Specifically, the position estimation unit F4 calculates the residual sum of squares RSS only for the candidate points in the corresponding area Cs of the LF transmission antenna 32 having the highest intensity observation value Bo. With such a configuration, the calculation load of the position estimation unit F4 can be reduced.

It should be noted that the mobile terminal 2 can basically be expected to be present in the corresponding area Cs of the LF transmission antenna 32 having the highest intensity observation value Bo. Therefore, by limiting the calculation target of the residual sum of squares RSS (in other words, the search range of the terminal position) as in the present embodiment, there is less risk that the position estimation accuracy will deteriorate than in the third comparison configuration. That is, according to the above configuration, it is possible to suppress the calculation amount while improving the position estimation accuracy as compared with the first comparison configuration and the second comparison configuration.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications described below are also included in the technical scope of the present disclosure. Also, various modifications can be implemented without departing from the scope of the invention. For example, the following various modified examples can be appropriately combined and implemented within a range in which technical contradiction does not occur.

It should be noted that members having the same functions as the members described in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted. Further, when only a part of the configuration is mentioned, the configurations of the above-described embodiments can be applied to the other parts.

上記式は、アンテナコイルのループ半径ａよりも距離ｒのほうが十分に大きいものとして近似している。式８の「μ_０」は、磁気定数である。「Ｉ」はアンテナコイルに流す電流値を示す。式８中の「ｒ」は、ＬＦ送信アンテナ３２の搭載位置（Ｘ_ｉ，Ｙ_ｉ，Ｚ_ｉ）から任意の候補点Ｐ（Ｘ_ｐ，Ｙ_ｐ，Ｚ_ｐ）までの距離を表す。また、θは、アンテナの搭載位置から候補点Ｐに向かうベクトルとアンテナの軸とがなす角度を表す。なお、上記式８に示すｒとθは、アンテナ軸がＹ軸に平行となる姿勢においては式９ａ、９ｂ（以降、式９とまとえて記載）の関係を満たす。図９は、座標空間距離ｒ、ピッチ角θ、ＬＦ送信アンテナ３２の搭載位置（Ｘ_ｉ，Ｙ_ｉ，Ｚ_ｉ）、候補点の位置（Ｘ_ｐ，Ｙ_ｐ，Ｚ_ｐ）の相互関係を示す図である。式９ｂの内容（主として分子）は、アンテナ軸の向きに応じて適宜変更されればよい。

ところで、強度観測値Ｂｏ１〜Ｂｏ４や、各アンテナの座標を式８、式９に代入すると、Ｘ_ｐ，Ｙ_ｐ，Ｚ_ｐの３つを変数とする連立方程式が得られる。よって、当該連立方程式を解けば、端末位置としての候補点（Ｘ_ｐ，Ｙ_ｐ，Ｚ_ｐ）を特定可能なように思われる。しかしながら、これらの連立方程式を解くことは現実的には容易でない。加えて、受信強度，ＬＦ送信アンテナ３２の位置，定数ｋ等に誤差を含む場合には、解が不定になる。対して、以上で述べた方法によれば、より確からしい端末位置を推定できるといった利点を有する。 [Modification 1]
In the above-described embodiment, the mode in which the intensity estimation value for each candidate point is specified using the intensity distribution map is disclosed, but the present invention is not limited to this. The magnetic field strength of the LF transmission antenna 32 at an arbitrary candidate point P(X _p , Y _p , Z _p ) can be formulated as the following Expression 8 using Biot-Savart's law. Therefore, the intensity estimation value (in other words, theoretical value) for each candidate point may be calculated by the following Expression 8. Whether the LF transmission antenna 32 is a loop antenna or a bar antenna, the magnetic field strength distribution of the LF transmission antenna 32 can be approximately calculated by the above equation 8.

The above equation is approximated by assuming that the distance r is sufficiently larger than the loop radius a of the antenna coil. “Μ ₀ ”in Equation 8 is a magnetic constant. “I” indicates the value of current flowing through the antenna coil. “R” in Expression 8 represents the distance from the mounting position (X _i , Y _i , Z _i ) of the LF transmission antenna 32 to an arbitrary candidate point P(X _p , Y _p , Z _p ). Further, θ represents an angle formed by the vector from the mounting position of the antenna to the candidate point P and the axis of the antenna. Note that r and θ shown in Expression 8 above satisfy the relationship of Expressions 9a and 9b (hereinafter referred to as Expression 9) in a posture in which the antenna axis is parallel to the Y axis. FIG. 9 shows the mutual relationship among the coordinate space distance r, the pitch angle θ, the mounting position (X _i , Y _i , Z _i ) of the LF transmission antenna 32, and the position (X _p , Y _p , Z _p ) of the candidate point. It is a figure. The content of Equation 9b (mainly the numerator) may be appropriately changed according to the orientation of the antenna axis.

By the way, by substituting the intensity observation values Bo1 to Bo4 and the coordinates of the respective antennas into the equations 8 and 9, a simultaneous equation having three variables X _p , Y _p , and Z _p as variables is obtained. Therefore, it seems that the candidate points (X _p , Y _p , Z _p ) as the terminal position can be identified by solving the simultaneous equations. However, solving these simultaneous equations is not easy in reality. In addition, if the reception strength, the position of the LF transmission antenna 32, the constant k, and the like include errors, the solution becomes indefinite. On the other hand, the method described above has an advantage that a more probable terminal position can be estimated.

[Modification 2]
For example, as shown in FIG. 10, the position estimation unit F4 uses the intensity distribution map to identify a curved surface (that is, a contour surface) for which the reception intensity is the intensity observation value Bo, and determines from the target candidate point to the contour surface. The distance may be calculated as the residual g. The residual g may be calculated for each combination of the candidate point and the antenna. The residual sum of squares RSS for a certain target candidate point may be the sum of squares of the residual g of each antenna for the target candidate point.

The residual g may be the difference between the coordinate space distance r from the candidate point P to the antenna and the estimated distance s determined based on the intensity observation value Bo. The coordinate space distance r is a linear distance from the candidate point P in the three-dimensional space coordinate system to the mounting position of the antenna, and may be calculated using each coordinate. The estimated distance s is a parameter corresponding to the distance r, which is determined by substituting the pitch angle θ and the intensity observation value Bo into the equation 8. The estimated distance s may be calculated by the following Expression 10 that is a modification of Expression 8. K in Expression 10 is a constant parameter determined according to μ ₀ , I, and a, for example, k=μ ₀ Ia ² /2.

[Modification 3]
The above-described embodiment discloses a configuration in which the residual sum of squares RSS is calculated for all candidate points existing in the candidate area, and the candidate point having the smallest residual sum of squares RSS is adopted as the terminal position. However, it is not limited to this. For example, the position estimation unit F4 may be configured to adopt a candidate point whose residual sum of squares RSS is less than a predetermined allowable threshold as the terminal position. This configuration corresponds to a configuration in which the search process is terminated when a candidate point whose residual sum of squares RSS is less than a predetermined allowable threshold is found in the process of repeating steps S104 to S108. With such a configuration, the amount of calculation related to position estimation can be further reduced.

It should be noted that the concept of the allowable threshold may be introduced also in the above-described embodiment. If the minimum value of the residual sum of squares RSS is equal to or larger than a predetermined allowable threshold, the position may be treated as indefinite. With such a configuration, it is possible to reduce the risk of adopting an uncertain position as the terminal position. The specific value of the allowable threshold may be appropriately adjusted based on the required position estimation accuracy and the like.

[Modification 4]
The mounting positions of the LF transmission antennas 32a to 32d are not limited to the above-described aspect. Each LF transmission antenna 32 can be mounted in various positions. For example, the LF transmission antenna 32a may be arranged near the right end of the ceiling. The right end portion of the ceiling portion corresponds to a portion with which the upper end portion of the driver's seat door abuts. Further, the LF transmission antenna 32a may be arranged in the center arranged on the right side of the vehicle. The LF transmission antenna 32b should just be arrange|positioned in the position symmetrical left and right with the LF transmission antenna 32a. The LF transmission antenna 32c may be attached to the overhead console, the central portion of the ceiling surface of the vehicle interior, the instrument panel, or the like. The LF transmission antenna 32d may be arranged inside the seating surface of the rear seat or the back portion.

Further, the mounting postures of the LF transmission antennas 32a to 32d are not limited to the above-described aspect. The LF transmission antennas 32a to 32b may be mounted such that the axial direction of the antenna is along the vehicle width direction, or the LF transmitting antennas 32a and 32b are mounted such that the axial direction of the antenna is along the vehicle height direction. The LF transmission antenna 32a and the LF transmission antenna 32b may be attached in different mounting postures. For example, the LF transmission antenna 32a may be mounted such that the axial direction of the antenna extends along the vehicle front-rear direction, while the LF transmission antenna 32b may be mounted such that the antenna axial direction extends along the vehicle width front-rear direction. The LF transmission antenna 32c and the LF transmission antenna 32d may be attached such that the axial direction of the antenna is along the vehicle front-rear direction or the vehicle height direction. The LF transmission antenna 32c and the LF transmission antenna 32d may be attached in different mounting postures. For example, the LF transmission antenna 32c may be attached such that the axial direction of the antenna extends along the vehicle front-rear direction, while the LF transmission antenna 32b may be attached such that the antenna axial direction extends along the vehicle width front-rear direction.

[Modification 5]
In the above-described embodiment, the mode in which the candidate points are set uniformly (at regular intervals) within the search range SR is disclosed, but the mode of setting the candidate points is not limited to this. As shown in FIG. 11, the candidate points may be set more densely in the vicinity of the window than in the area other than the vicinity of the window. For example, the candidate points may be set at intervals of 4 cm in the area other than the vicinity of the window, while the candidate points may be set at intervals of 2 cm near the window. In FIG. 11, d1 indicates the setting interval of the candidate points other than near the window portion, and d2 indicates the setting interval of the candidate points near the window portion. The window portion here means an area within 10 cm from the window.

According to the above setting mode, it is possible to improve the determination accuracy in the vicinity of the window where the terminal position is likely to be erroneously determined. As a result, it is possible to improve the accuracy of determining whether the mobile terminal 2 is inside the vehicle compartment or outside the vehicle compartment. Further, in a configuration in which the body of the vehicle transmits radio waves, the candidate points may be set closer to the side surface portion of the vehicle than to the area other than the window portion. Further, the setting density of the candidate points may be made sparse as the distance from the vehicle increases.

[Modification 6]
In the above-described embodiment, the mode in which the vehicle side device 3 includes the area specifying unit F3 and the position estimating unit F4 is disclosed, but the arrangement mode of various functions is not limited to this. The area specifying unit F3 and the position estimating unit F4 may be included in the mobile terminal 2. In that case, it is preferable that the mobile terminal 2 be configured to wirelessly transmit data indicating the estimation result of the terminal position with respect to the vehicle to the vehicle side device 3.

[Modification 7]
In the above, the aspect which estimates the position of the portable terminal 2 using the reception intensity in the portable terminal 2 of the signal transmitted from the vehicle was disclosed, but it is not limited to this. In a configuration in which the vehicle-side device includes a plurality of configurations (vehicle-mounted receiver) for receiving a signal from the mobile terminal 2, the terminal position is estimated based on the reception intensity of the signal from the mobile terminal 2 at each vehicle-mounted receiver. It may be configured as follows. Hereinafter, an example corresponding to such a technical idea will be described as a modified example 7. The vehicle-side device 3 of this modified example corresponds to a vehicle position estimation device. Various technical ideas disclosed as Modifications 1 to 6 and Modification 8 described later can be applied to this modification as appropriate.

The vehicle-side device 3 and the mobile terminal 2 in this modification are each configured to be capable of performing communication (hereinafter referred to as short-range communication) that conforms to a predetermined short-range wireless communication standard. As the short-range wireless communication standard, for example, Bluetooth Low Energy (Bluetooth is a registered trademark), Wi-Fi (registered trademark), ZigBee (registered trademark), or the like can be adopted. The short-range wireless communication standard may be, for example, one that can provide a communication distance of several meters to several tens of meters. The vehicle-side device 3 and the mobile terminal 2 of the present embodiment are configured to perform wireless communication in compliance with the Bluetooth Low Energy standard, for example.

As shown in FIG. 12, the mobile terminal 2 in this modification includes a mobile-side control unit 23 and a mobile-side communication unit 26. The mobile communication unit 26 is a communication module for performing near field communication. The configuration and function of the mobile communication unit 26 are the same as those of the vehicle-mounted communication device 34 described later. However, the mobile communication unit 26 does not have to include the reception strength determination unit C3. The mobile-side communication unit 26 is connected to the mobile-side control unit 23 so that they can communicate with each other. The mobile-side controller 23 controls the operation of the mobile-side communication unit 26.

The signal transmitted by the mobile terminal 2 as the short-range communication includes the transmission source information. The transmission source information is, for example, unique identification information (hereinafter referred to as a terminal ID) assigned to the mobile terminal 2. The terminal ID functions as information for identifying the other communication terminal and the mobile terminal 2. In addition, the mobile terminal 2 wirelessly transmits a communication packet including transmission source information at a predetermined transmission interval to notify the surrounding communication terminals having a short-range communication function of the existence of itself (that is, To advertise). Hereinafter, for convenience, a communication packet that is periodically transmitted for the purpose of advertising is referred to as an advertisement packet.

The vehicle-side device 3 receives a signal (for example, an advertisement packet) transmitted from the mobile terminal 2 by the above-mentioned short-range communication function, so that the mobile terminal 2 is within a range in which the mobile device 2 can perform short-range communication with the vehicle-side device 3. Detects the presence. In this embodiment, as an example, the vehicle-side device 3 is configured to detect the presence of the mobile terminal 2 in the communication area by receiving the advertisement packets sequentially transmitted from the mobile terminal 2. However, it is not limited to this. As another aspect, the mobile terminal 2 is present in the communication area of the vehicle side device 3 based on the fact that the vehicle side device 3 sequentially transmits an advertisement packet and a communication connection (so-called connection) with the mobile terminal 2 is established. It may be configured to detect the action.

The vehicle-side device 3 of the present embodiment includes a plurality of vehicle-mounted communication devices 34a to 34d as communication modules for performing short-range communication with the mobile terminal 2, as shown in FIG. When the in-vehicle communication devices 34a to 34d are not distinguished from each other, the in-vehicle communication device 34 is described. Each in-vehicle communication device 34 is connected to the smart ECU 31 via a dedicated communication line or in-vehicle network so as to be capable of mutual communication. A unique communication device number is set for each in-vehicle communication device 34. The communication device number is information corresponding to the terminal ID for the mobile terminal 2. The communication device number functions as information for identifying the plurality of vehicle-mounted communication devices 34.

The vehicle-mounted communication devices 34a to 34d are mounted at appropriately designed locations in the vehicle. For example, the vehicle-mounted communication devices 34a to 34d are attached to the positions illustrated as the mounting positions of the LF transmission antenna 32 in the above-described embodiment and modification 4. Of course, the mounting position of each in-vehicle communication device 34 can be appropriately changed.

FIG. 13 schematically shows the electrical configuration of the vehicle-mounted communication device 34. As shown in FIG. 13, the vehicle-mounted communication device 34 includes an antenna 341, a transmission/reception unit 342, and a communication microcomputer 343. The antenna 341 is an antenna for transmitting and receiving radio waves in a frequency band (for example, 2.4 GHz band) used for near field communication. The antenna 341 is electrically connected to the transmitting/receiving unit 342. As the antenna 341, various antenna structures such as a patch antenna, a dipole antenna, a monopole antenna, an inverted F antenna and an inverted L antenna can be adopted.

The transmission/reception unit 342 is a circuit module that performs signal processing related to signal transmission/reception. The transmission/reception unit 342 is connected to the communication microcomputer 343 so that they can communicate with each other. The transmission/reception unit 342 includes a transmission circuit C1, a reception circuit C2, and a reception strength determination unit C3. The transmission circuit C1 modulates a signal input from the smart ECU 31 via the communication microcomputer 343, outputs the signal to the antenna 341, and emits it as a radio wave.

The receiving circuit C2 demodulates the signal received by the antenna 341 and provides it to the communication microcomputer 343. The reception strength determination unit C3 is configured to sequentially detect the electric field strength (that is, the reception strength) of the signal received by the antenna 341. The reception strength determination unit C3 can be realized by various circuit configurations. The reception strength detected by the reception strength determination unit C3 is associated with the terminal ID included in the reception data and sequentially provided to the communication microcomputer 343. It should be noted that the reception intensity may be expressed in the unit of power [dBm], for example. For convenience, the data in which the reception strength and the terminal ID are associated with each other is referred to as reception strength data. The vehicle-mounted communication device 34 including the reception circuit C2 and the reception intensity determination unit C3 corresponds to a vehicle-side receiver.

The communication microcomputer 343 is a microcomputer that controls data exchange with the smart ECU 31. In addition, when the communication microcomputer 343 acquires the reception intensity data from the reception intensity determination unit C3, the communication microcomputer 343 sequentially provides the reception intensity data to the smart ECU 31.

In the above configuration, the information processing unit 311 of the smart ECU 31 identifies the terminal position by the same method as in the above-described embodiment. That is, the area identifying unit F3 identifies the corresponding area Cs in which the mobile terminal 2 exists, based on the reception intensity of the signal from the mobile terminal 2 in each in-vehicle communication device. The corresponding area Cs is preset for each in-vehicle communication device 34. The position estimating unit F4 calculates the residual sum of squares RSS for each candidate point existing in the corresponding area Cs specified by the area specifying unit F3 within the search range SR. Then, in the corresponding area Cs, it is determined that the mobile terminal 2 exists at the candidate point having the smallest residual sum of squares RSS. Since the in-vehicle communication device 34 has the antenna 341 built therein, the corresponding area Cs for each in-vehicle communication device 34 corresponds to the corresponding area for each antenna. The mounting position of the vehicle-mounted communication device 34 corresponds to the mounting position of the antenna.

[Modification 8]
In the above-described embodiment, the aspect in which the three-dimensional space including the outside of the vehicle, which is within 1 m from the side surface portion and the rear end portion of the vehicle, is set as the search range SR, the range set as the search range SR is set to this. Not limited. The range set as the search range SR can be changed as appropriate. Considering the Thatcham requirement and the like, Dx defining the size of the search range SR in the vehicle width direction may be set to 2 m. Further, in the configuration in which the three-dimensional space including the outside of the vehicle compartment is set as the search range, the hood of the vehicle, the roof shape, or the bottom of the vehicle body may be set as the non-search area. It is preferable that the corresponding area for each antenna is set so as not to include the non-search area.

Further, the search range SR may be limited to only the passenger compartment. In that case, the corresponding area Cs of each antenna may also be set in the passenger compartment. 14A conceptually shows the corresponding area Cs of the LF transmission antenna 32a, and FIG. 14B conceptually shows the corresponding area Cs of the LF transmission antenna 32b. 14C conceptually shows the corresponding area Cs of the LF transmission antenna 32c, and FIG. 14D conceptually shows the corresponding area Cs of the LF transmission antenna 32d.

<Additional notes>
The control unit and the method thereof described in the present disclosure may be realized by a dedicated computer that configures a processor programmed to execute one or a plurality of functions embodied by a computer program. Further, the device and the method described in the present disclosure may be realized by a dedicated hardware logic circuit. Furthermore, the device and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transition tangible recording medium as an instruction executed by the computer. That is, the means and/or functions provided by the smart ECU 31 can be provided by software recorded in a substantive memory device and a computer that executes the software, only software, only hardware, or a combination thereof. Some or all of the functions of the smart ECU 31 may be realized as hardware. The mode of realizing a certain function as hardware includes a mode of realizing using one or more ICs.

1 vehicle position estimation system, 2 mobile terminal, 3 vehicle side device, 21 LF receiving antenna, 22 LF receiving unit (mobile side receiving unit), 23 mobile side control unit, 24 UHF transmitting unit, 25 UHF transmitting antenna, 26 mobile Side communication unit, 31 smart ECU, 32.32a to 32d LF transmission antenna (vehicle side antenna), 33 UHF receiver, 34.34a to 34d vehicle-mounted communication device (vehicle side receiver), 221, C3 reception intensity determination unit, 311 information processing unit, 312 LF driver, 341 antenna, 342 transmission/reception unit, 343 communication microcomputer, C1 transmission circuit, C2 reception circuit, F1 transmission processing unit, F2 response acquisition unit, F3 area identification unit, F4 position estimation unit, M1 correspondence Area storage, M2 intensity distribution storage

Claims (9)

A mobile terminal (2) carried by a user of the vehicle and a vehicle side device (3) used in the vehicle perform wireless communication to estimate a terminal position which is the position of the mobile terminal with respect to the vehicle. A vehicle position estimation system (1),
A search range, which is a range for setting a candidate point as a candidate for the terminal position, is preset with the vehicle as a reference,
The vehicle-side device includes a plurality of vehicle-side antennas (32, 32a to 32d) that transmit radio signals to the mobile terminal,
The mobile terminal is
A portable receiver (22) for receiving a signal from the vehicle antenna,
An intensity determination unit (221) that determines the reception intensity, which is the intensity of the signal received by the mobile-side reception unit,
The vehicle side device or the mobile terminal,
Based on the intensity observation value, which is the reception intensity of the signal transmitted from each of the vehicle-side antennas, which is determined by the intensity determination unit, and the corresponding area preset for each of the vehicle-side antennas, An area specifying unit (F3) for specifying a candidate area which is an area where the mobile terminal can exist;
Based on the intensity observation value of the signal transmitted from each vehicle-side antenna, for each of the candidate points, an error evaluation value indicating the degree of deviation between the candidate point and the true terminal position is calculated, and the error evaluation is performed. A position estimation unit (F4) that employs the candidate point having the smallest value or the candidate point having the error evaluation value equal to or less than a predetermined allowable threshold as the terminal position;
The position estimating unit specifies the terminal position by calculating the error evaluation value for the candidate points existing in the candidate area specified by the area specifying unit in the search range. A configured vehicle position estimation system. The vehicle position estimation system according to claim 1, wherein
The position estimation unit,
For each of the vehicle-side antennas, the reception intensity of the signal transmitted from the vehicle-side antenna is an iso-intensity surface that is a curved surface that is the intensity observation value corresponding to the vehicle-side antenna,
A vehicle position estimation system configured to calculate a sum of squares of a distance from the candidate point to the iso-intensity surface for each vehicle-side antenna as the error evaluation value. The vehicle position estimation system according to claim 1, wherein
An intensity distribution storage unit (M2) that stores an intensity distribution model that is data indicating a distribution of reception intensity for each vehicle-side antenna within the search range,
The position estimation unit uses the intensity distribution model for each vehicle-side antenna stored in the intensity distribution storage unit to obtain an intensity estimation value that is an estimation value of the reception intensity at the candidate point by the vehicle-side antenna. Specify for each
A vehicle position estimation system configured to calculate the sum of squares of the difference between the intensity estimation value and the intensity observation value for each vehicle-side antenna as the error evaluation value for the candidate point. The vehicle position estimation system according to any one of claims 1 to 3,
The vehicle position estimation system, wherein the vehicle-side antenna is configured by using an antenna having an ellipsoidal radiation characteristic. The vehicle position estimation system according to any one of claims 1 to 4,
A three-dimensional space within 1 m from the side surface of the vehicle is set in the search range,
Above the hood of the vehicle, the roof shape, and the bottom of the vehicle body are set as non-search areas,
The vehicle position estimation system, wherein none of the corresponding areas of the vehicle-side antennas include the non-search area. The vehicle position estimation system according to any one of claims 1 to 5,
In the search range, a vehicle position estimation system in which an area within a certain distance from a window of the vehicle has the candidate points set more densely than other areas in the search area. The vehicle position estimation system according to any one of claims 1 to 6,
If the difference between the highest intensity observation value and the second highest intensity observation value among the intensity observation values for each vehicle-side antenna is less than a predetermined integration threshold value, A range obtained by integrating the corresponding area of the vehicle-side antenna for which the highest intensity observation value is obtained and the corresponding area of the vehicle-side antenna for which the second highest intensity observation value is obtained is A vehicle position estimation system configured to be set in a candidate area. The vehicle position estimation system according to any one of claims 1 to 7, which is used in a vehicle in which a body is made of a material that allows radio waves to pass therethrough. A vehicle position estimation device that estimates a terminal position, which is a position of the portable terminal with respect to the vehicle, by performing wireless communication with a portable terminal carried by a user of the vehicle,
A search range, which is a range for setting a candidate point as a candidate for the terminal position, is preset with the vehicle as a reference,
A plurality of vehicle-side receivers (34, 34a to 34d) configured to receive the wireless signal transmitted from the mobile terminal and to detect the reception intensity of the received wireless signal;
Based on an intensity observation value that is the reception intensity at each of the vehicle-side receivers and a corresponding area that is preset for each of the vehicle-side receivers, a candidate area that is an area where the mobile terminal can exist is selected. An area specifying unit (F3) to specify,
Based on the intensity observation value at each vehicle-side receiver, for each of the candidate points, an error evaluation value indicating the degree of deviation between the candidate point and the true terminal position is calculated, and the error evaluation value is the most A position estimation unit (F4) that adopts the candidate point that becomes smaller or the candidate point that the error evaluation value becomes equal to or less than a predetermined allowable threshold as the terminal position,
The position estimating unit specifies the terminal position by calculating the error evaluation value for the candidate points existing in the candidate area specified by the area specifying unit in the search range. A configured vehicle position estimation device.

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