JP7097941B2 - Vehicle terminal position estimation system - Google Patents

Description

The present application relates to a mobile terminal position estimation system for vehicles.

Conventionally, there is a smart entry / smart start system (hereinafter referred to as a smart system) as a system that estimates the relative position of a mobile terminal with respect to a vehicle using radio waves and enhances convenience for users by using this. The in-vehicle radio sends challenge data in the LF (Low Frequency) band around 100 KHz to the mobile terminal, and the mobile terminal responds to this and sends a response signal in the UHF (Ultra High Frequency) band of 1 GHz or less to the in-vehicle radio. Reply. When this series of authentication communications is established, it becomes possible to control vehicle equipment such as locking and unlocking doors. This smart system unlocks or locks the door when the user approaches the vehicle or touches the doorknob, even if the mobile terminal is kept in a pocket or bag, and depending on the vehicle model, the door is automatically opened when the user leaves the vehicle. To lock. Also. When the user gets into the vehicle interior, the engine is started by pressing the engine start button installed in the vehicle interior without pointing the key at the keyhole as in the conventional system. Due to theft and safety issues, the vehicle is not unlocked in the outdoor area of about 2 m or more from the end of the vehicle body, and is not locked if there is a mobile terminal in the vehicle interior. In addition, the engine is allowed to start only when the mobile terminal is in the passenger compartment.

The electronic key system described in Patent Document 1 is based on a conventional method in which a mobile terminal receives an LF band signal transmitted by an in-vehicle radio, and has a number of transmitting antennas for transmitting the LF band signal in the vehicle interior. It will be installed in several places around the body outside the vehicle interior. Since there is a certain relationship between the reception strength of radio waves and the communication distance, the communication distance can be estimated from the reception strength. In addition, as the nature of radio waves in the LF band, the amount of attenuation of the radio wave intensity is large due to the shielding effect of the vehicle body, and the leakage of the LF band signal transmitted from the inside of the vehicle to the outside of the vehicle is small, so that the mobile terminal can be used. It is determined whether it is inside or outside the vehicle interior, and it is estimated in which area outside the vehicle interior. However, the propagation distance of radio waves in the LF band is as short as several meters, and the obtained position information is often information on the presence or absence of existence in the region near the antenna that transmits the LF charged wave.

The electronic key position estimation device described in Patent Document 2 performs position estimation using radio waves in the UHF band. The in-vehicle UHF antenna has an array shape and measures the arrival angle (AOA: Angle Of Arrival) of the UHF charged wave transmitted by the electronic key. The incident direction is obtained from the arrival angle information of a plurality of antennas, and the position of the electronic key is estimated from the intersection of a plurality of straight lines indicating the plurality of incident directions. Then, from the estimated position, it is determined whether the vehicle exists in the vehicle interior area or the vehicle interior area. In order to estimate the position of the electronic key using the UHF band radio wave used in the response signal of the keyless system, the LF charged wave transmission circuit and the electron are on the vehicle side like the electronic key system described in Patent Document 1. Since it is not necessary to mount an LF charged wave receiving circuit on the key side, the effect of simplifying the entire system can be expected. Further, since the UHF charged wave has a longer communication distance than the LF charged wave, there is a possibility that a wider area range can be set as compared with the case where the LF charged wave is used as the positioning range.

The portable terminal key system described in Patent Document 3 performs position estimation using a frequency band different from the radio waves of the LF band and the UHF band used in the electronic keys described in Patent Document 1 and Patent Document 2. As the radio wave, Bluetooth (registered trademark) in the GHz band, which is standardly used in information terminals such as smartphones, is used. The strength of the received signal of the radio wave when the in-vehicle antenna installed on the outer wall of the vehicle and the mobile terminal communicate with each other is measured, and the inside / outside of the vehicle is judged while considering the attenuation effect due to the influence of the vehicle body. By using standardized radio waves such as Bluetooth, it can be expected that information terminals that are widely used in smartphones and the like will be used as electronic keys.

The vehicle position estimation system described in Patent Document 4 performs position estimation using radio waves having a higher frequency than the radio waves used in Patent Document 1, Patent Document 2, and Patent Document 3. As the radio wave, UWB (Ultra Wide Band) in the GHz band, which is being adopted in information terminals such as smartphones, is used. UWB has a higher frequency than Bluetooth and has a wide band of 500 MHz or more, so it can send and receive impulse-like signals. Therefore, the time resolution is high, and high accuracy can be expected by the distance measurement based on the propagation time (TOF: Time Of Flight). Three or more in-vehicle communication devices are attached to different positions of the vehicle, and the spatial position with respect to the vehicle is calculated from a plurality of distance information obtained by communication with the mobile terminal. If communication failure occurs and detailed position calculation is not possible, the position of the mobile terminal is limited to the area near the antenna. Similar to the mobile terminal key system described in Patent Document 3, it can be expected that the possibility of using an information terminal as an electronic key will be expanded by using UWB, which is becoming widespread in smartphones and the like. Further, the signal reception strength is greatly affected by the variation depending on the model of the end mobile terminal and the holding method of the user, and the positioning using the distance information based on the propagation time as in Patent Document 4 is more accurately advantageous. It can be said that.

Patent No. 4723415 JP-A-2018-199971 Patent No. 6321449 International Publication No. 2020/158310

A smart system is a typical example of a system that wirelessly obtains the position of a mobile terminal with respect to a vehicle. In the smart system, it is estimated whether the mobile terminal is in the vehicle interior or in the vicinity of the vehicle interior, and control is performed to allow the user to start the engine, lock and unlock the door. In this case, for safety reasons, the engine must be prohibited when the mobile terminal is outside the vehicle interior, and when the mobile terminal is separated from the end of the body by a certain distance or more (about 2 m), door control is performed. Must be banned.

Further, as another example of the system for estimating the position of the mobile terminal, there is a remote parking control system (hereinafter referred to as an RPC system). In the RPC system, the user controls the parking movement of the vehicle by the mobile terminal. Also in the RPC system, for safety reasons, control is prohibited when the mobile terminal is separated from the vehicle by a certain distance or more. When constructing the RPC system, it is desirable to be able to estimate the position of the mobile terminal in an area of up to about 6 m in consideration of convenience.

As a system for estimating the position of a mobile terminal over a longer distance and a wider area, there are a welcome system and a relay attack prevention system. The welcome system provides a service function of turning on a light or the like when a user approaches within a certain distance from the vehicle. A relay attack is to illegally relay the authentication communication between the vehicle and the mobile terminal by the keyless system, and access the vehicle by disguising the mobile terminal in the distance as if it were near the vehicle, and prevent this. Is important. In constructing a welcome system or a relay attack prevention system, a technique for estimating the distance between a mobile terminal and a vehicle of several meters to 100 meters is required. As described above, there are various systems that require the position estimation of the mobile terminal from the judgment of the inside and outside of the vehicle to the long-distance measurement. It can be said that it is desirable for cost reduction.

Conventionally, a mobile terminal has generally been configured as a dedicated terminal. However, with the diversification of control contents by users, the increasing demand for sophistication of human interfaces, and the spread of electronic keys used for car sharing, mobile phones such as general smartphones are used instead of dedicated mobile terminals. The movement to use information terminals is becoming more active. Therefore, it is desirable that the communication device can be miniaturized to the extent that it can be mounted on a general mobile information terminal, and that the radio wave used for position estimation adopts the communication method itself mounted on the information terminal.

Since the LF charged wave used in the electronic key system described in Patent Document 1 has a long wavelength and a large amount of attenuation due to the vehicle body, it is determined whether the position of the mobile terminal is inside or outside the vehicle based on the reception intensity. It is suitable for the communication method for using. However, there is a problem that the amount of attenuation due to the distance is large and the communicable area is limited to the vicinity of the outside of the vehicle interior. Furthermore, since the wavelength is long, the size of the receiving antenna mounted on the mobile terminal is large, which is a limitation of miniaturization. When mounting on a mobile information terminal such as a smartphone, it is necessary to install a new antenna, but it is difficult to interpolate due to the size.

In the electronic key position estimation device described in Patent Document 2, the position of the mobile terminal is estimated using the UHF charged wave. Compared to the LF charged wave, the communication distance is long, and the region where the position can be estimated can be set wider than that of the LF charged wave. The arrival angle of radio waves is measured by an array antenna, and the position of the mobile terminal is estimated from the intersection of straight lines indicating the radio wave direction based on the arrival angles measured by the array antennas installed at multiple locations in the vehicle interior. However, radio waves with a high frequency (short wavelength) above the UHF band tend to be strongly affected by obstacles, window frame shape, seat layout, presence / absence of occupants, movement, etc., and have poor visibility (NLOS: No). In the Line Of Sight) area, reflection and refraction occur in a complicated manner, and it is not possible to obtain correct angle information. In a situation where the vehicle interior environment changes sequentially, the angle information also changes from moment to moment. Therefore, in the antenna layout as described in Patent Document 2 and the position estimation process using the angle information, the vehicle interior / outdoor determination is made. , And it is considered that there will be a large variation in the estimation of the position outside the vehicle interior. Further, when mounted on a smartphone or the like, the UHF charging wave is newly installed as in the electronic key system described in Patent Document 1, so that additional hardware changes are required.

The mobile terminal key system described in Patent Document 3 uses Bluetooth in the GHz band. Since Bluetooth has a high frequency and a short wavelength, the antenna can be miniaturized, and it is installed as standard on mobile information terminals such as smartphones. This has the advantage that no additional hardware is required. In Patent Document 3, whether the received radio wave is a direct wave or a combined wave with a reflected wave by a stationary object is determined from the information obtained by calculating the reception intensity of the radio wave received by the antenna installed in the vehicle. Judgment is made, and the inside / outside of the vehicle is judged while using the judgment result. However, the reception strength varies depending on the output level of the mobile information terminal, and this output level depends on the model of the mobile information terminal and also depends on how the mobile information terminal is held. In addition, since the surrounding communication environment changes from moment to moment, it is considered that it is not easy to make an indoor / outdoor determination based on the reception strength. Further, since this method targets only the determination of the inside and outside of the vehicle interior, it is not possible to estimate the position outside the vehicle interior.

The vehicle position estimation system described in Patent Document 4 uses UWB in the GHz band. Since UWB has a high frequency and a short wavelength, the antenna can be miniaturized, and its installation in mobile information terminals such as smartphones is expanding. Since the distance measurement method based on the propagation time using the UWB impulse waveform can measure by the direct wave, the combined wave by the direct wave and the reflected wave, which is a problem in the method by the strength of the received radio wave as in Patent Document 3, that is, It has the advantage of being less susceptible to multipath. However, since the mobile terminal in the NLOS area does not reach the direct wave and reaches the antenna via complicated reflection, the measured distance is often larger than the actual distance. Therefore, it is necessary to install the antenna of the in-vehicle communication device at a position with good visibility, which makes the layout of the antenna difficult. In addition, it is conceivable that the communication route changes due to the arrangement and movement of the passengers, distance errors and variations occur, and cases in which the judgment inside and outside the vehicle is erroneously occur frequently.

Therefore, an object of the present application is to provide a mobile terminal position estimation system for a vehicle in which an error in estimating the presence or absence of the presence or absence of the mobile terminal is unlikely to occur due to the reflected wave reflected in the vehicle interior.

The mobile terminal position estimation system for vehicles according to the present application is
Multiple antennas attached to the vehicle that receive radio waves transmitted from the mobile terminal owned by the user of the vehicle,
For each of the plurality of antennas, a wireless communication unit that processes the radio wave signal received by the antenna and outputs information on the arrival angle at which the received radio wave arrives.
A mobile position estimation unit for determining whether the mobile terminal exists in the vehicle interior or outside the vehicle interior based on the information of the arrival angle of the plurality of antennas is provided.
Each of the plurality of antennas is arranged adjacent to each of the plurality of boundary surfaces through which radio waves can pass , in the normal direction of the respective boundary surfaces, so as to separate the inside and outside of the vehicle interior .
The portable position estimation unit compares the arrival angle information and the determination threshold value for each of the plurality of antennas, and the received radio wave causes the boundary surface on which the antennas are arranged adjacent to the vehicle interior to the outside of the vehicle interior. Determine whether it has penetrated or penetrated from outside the vehicle interior into the vehicle interior.
Based on the determination result of the transmission direction of the plurality of antennas, it is determined whether the mobile terminal exists in the vehicle interior or outside the vehicle interior.

According to the portable terminal position estimation system for vehicles according to the present application, since each antenna is arranged adjacent to each transmission boundary surface through which radio waves can be transmitted, the received radio wave is a reflected wave reflected in the vehicle interior. Regardless of whether it is a direct wave or not, the radio wave received by the antenna is a radio wave transmitted from the outside of the vehicle interior to the inside of the vehicle based on the information of the arrival angle of each antenna, or the transmission boundary surface is determined. It is possible to accurately detect whether the radio wave is transmitted from the inside of the vehicle to the outside of the vehicle. Therefore, regardless of the direct wave and the reflected wave, it is possible to accurately determine whether the mobile terminal exists in the vehicle interior or outside the vehicle interior.

It is a schematic block diagram of the mobile terminal position estimation system for a vehicle which concerns on Embodiment 1. FIG. It is a figure explaining the problem which concerns on the comparative example. It is a figure explaining the problem which concerns on the comparative example. It is a figure explaining the structure of the antenna which concerns on Embodiment 1. FIG. It is a figure explaining the calculation of the arrival angle which concerns on Embodiment 1. It is a figure explaining the determination by the arrival angle which concerns on Embodiment 1. FIG. It is a figure explaining the car interior / outside determination which concerns on Embodiment 1. It is a figure explaining the car interior / outside determination which concerns on Embodiment 1. It is a figure explaining the example of the vehicle interior and the antenna arrangement which concerns on Embodiment 1. FIG. It is a figure explaining the example of the vehicle interior and the antenna arrangement which concerns on Embodiment 1. FIG. It is a figure explaining the example of the vehicle interior and the antenna arrangement which concerns on Embodiment 1. FIG. It is a figure explaining the calculation of the distance which concerns on Embodiment 2. It is a figure explaining the determination by the arrival angle and the distance which concerns on Embodiment 2. It is a figure explaining the position estimation of the mobile terminal which concerns on Embodiment 2. FIG. It is a schematic block diagram of the mobile terminal position estimation system for a vehicle which concerns on Embodiment 3. FIG.

1. 1. Embodiment 1
The vehicle portable terminal position estimation system (hereinafter referred to as a position estimation system) according to the first embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a position estimation system. The position estimation system is based on a plurality of antennas 10 that communicate with the mobile terminal 50 owned by the user of the vehicle 1, a wireless communication unit 20 that processes the received signals of the plurality of antennas 10, and information processed by the wireless communication unit 20. It also includes a mobile position estimation unit 30 that estimates the position of the mobile terminal 50. The position estimation system is mounted on the vehicle.

1-1. Basic configuration <Mobile terminal 50>
The mobile terminal 50 is a mobile terminal possessed by the user of the vehicle. The mobile terminal 50 includes a mobile antenna 51 and a mobile wireless communication unit 52. The mobile wireless communication unit 52 transmits radio waves from the mobile antenna 51. Further, the mobile wireless communication unit 52 processes the radio wave signal transmitted from the antenna 10 or the like of the position estimation system and received by the mobile antenna 51. The portable wireless communication unit 52 includes a transmission / reception circuit for transmitting / receiving radio waves via the portable antenna 51, a control circuit for controlling the transmission / reception circuit, and a control circuit for processing signals transmitted / received by the transmission / reception circuit.

In the present embodiment, the mobile antenna 51 and the mobile wireless communication unit 52 transmit and receive radio waves of Bluetooth (registered trademark) Low Energy or Ultra Wide Band communication method. The mobile terminal 50 is a mobile information terminal including a smartphone. As the mobile antenna 51 and the mobile wireless communication unit 52, the antenna and the wireless communication unit that are standard equipment on the mobile information terminal are used. Therefore, it is possible to divert a mobile information terminal such as a smartphone owned by the user without preparing a mobile terminal dedicated to the position estimation system.

<Multiple antennas 10>
The plurality of antennas 10 are antennas that receive radio waves transmitted from the mobile terminal 50 possessed by the user of the vehicle 1, and are attached to the vehicle. In this embodiment, four antennas 10a, 10b, 10c, and 10d are provided. Two or more antennas 10 may be provided.

<Wireless communication unit 20>
The wireless communication unit 20 processes the radio wave signal received by the antenna 10 for each of the plurality of antennas 10 and outputs information on the arrival angle at which the received radio wave has arrived. The details of the processing contents will be described later.

In the present embodiment, a total of four wireless communication units 20a, 20b, 20c, and 20d are provided for each antenna 10, one for each antenna 10. Each wireless communication unit 20 is a communication device that performs data communication with a transmission / reception circuit that transmits / receives radio waves via the antenna 10, a control circuit that controls the transmission / reception circuit and processes signals transmitted / received by the transmission / reception circuit, a portable position estimation unit 30, and the like. It is composed of such things. The control circuit is composed of an arithmetic processing unit and the like. As the arithmetic processing unit, an information processing circuit such as a CUP (Central Processing Unit), a storage device, an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable Gate Array) is used. When a CPU and a storage device are used, the CPU executes a program stored in a storage device such as a flash memory, and each function is realized.

The antenna 10 and the wireless communication unit 20 transmit and receive radio waves of Bluetooth (registered trademark) Low Energy or Ultra Wide Band communication method.

<Mobile position estimation unit 30>
The mobile position estimation unit 30 determines whether the mobile terminal 50 is present in the vehicle interior or outside the vehicle interior based on the information on the arrival angles of the plurality of antennas 10. The details of the processing contents will be described later.

The mobile position estimation unit 30 includes an arithmetic processing device that performs information processing, a communication device that performs data communication with an external device such as the wireless communication unit 20, and the like. The arithmetic processing unit includes a CPU, a storage device, an information processing circuit such as an ASIC and an FPGA. When a CPU and a storage device are used, the CPU executes a program stored in a storage device such as a flash memory, and each function is realized.

The determination result of the presence or absence of the inside of the vehicle interior of the mobile terminal 50 determined by the mobile position estimation unit 30 and the estimated position of the mobile terminal 50 are transmitted to the control device of the vehicle. Then, the vehicle control device controls various vehicles such as permission to start the engine, permission to lock or unlock the door, permission to remote parking, etc. by the user based on the information transmitted from the mobile position estimation unit 30. conduct.

1-2. Suppression of estimation error due to reflected waves <Problems due to reflected waves>
FIG. 2 shows a diagram in which the passenger compartment 3 is modeled as a rectangular cuboid. The four side surfaces of the vehicle interior 3 are transparent surfaces such as glass, and the upper surface and the lower surface are non-transmissive surfaces such as an iron plate and reflect radio waves. Here, as a comparative example, a method of estimating the existence or nonexistence of the vehicle interior based on the multi-sided survey method using a distance, which is often used in the conventional method, will be described. In the comparative example, each antenna is composed of a single antenna element and measures the distance from the mobile terminal 50. Four antennas 15a, 15b, 15c and 15d are installed at the four corners of the upper surface. The position 2P of the mobile terminal 50 is estimated based on the distance between the antenna and the mobile terminal detected by each antenna. At this time, if the mobile terminal 50 is in an LOS (Line Of Sight) environment with good visibility for all antennas, a wave directly reaches between the mobile terminal and each antenna, and the position of the mobile terminal is accurate. It is thought that it can be estimated. However, the communication environment in the vehicle interior changes depending on the position of the mobile terminal, the position of the occupant, the arrangement of seats, the position of luggage, and the like. Depending on the situation, the mobile terminal becomes an NLOS (No Line Of Sight) environment in which the wave does not reach directly to one or more antennas, and the reflected wave reaches between the mobile terminal and the antenna. In the example of FIG. 2, the radio wave reflected on the lower surface reaches between the second antenna 15b and the mobile terminal, and the measurement distance is longer than in the case of the direct wave.

FIG. 3 shows the estimation result of the position of the mobile terminal 50 by the multi-sided survey method when the wave directly reaches the second antenna 15b and when the reflected wave reaches. In FIG. 3, a circle having a radius measured when the wave directly reaches the second antenna 15b (LOS) is shown by a dotted line, and the circle is measured when the reflected wave reaches the second antenna 15b (NLOS). A circle whose radius is a distance is shown by a broken line. When the direct wave arrives, the estimated position of the mobile terminal is inside the vehicle interior and no estimation error occurs, but when the reflected wave arrives, the estimated position 2P of the mobile terminal is outside the vehicle interior and an estimation error occurs. ing. As described above, in the comparative example in which the position is estimated by the distance measurement, the estimation error of the existence or nonexistence of the vehicle interior frequently occurs due to the reflected wave.

Further, although not shown in the figure, even when the information on the arrival direction of the radio wave to each antenna is used as in the technique of Patent Document 2, the same applies when the information on the arrival direction of the reflected wave is used. There is an error in estimating the position of the mobile terminal. Therefore, there is a need for a position estimation system in which the estimation error of the presence or absence of the presence or absence of the presence or absence of the mobile terminal is unlikely to occur due to the reflected wave reflected in the vehicle interior.

<Arrangement of the antenna 10 adjacent to the transmission boundary surface 12>
Therefore, as shown in FIG. 1, each of the plurality of antennas 10 is adjacent to each of the plurality of boundary surfaces 12 (hereinafter referred to as transmission boundary surfaces 12) through which radio waves can pass, separating the inside of the vehicle and the outside of the vehicle. And are arranged. Then, as described above, the wireless communication unit 20 processes the radio wave signal received by the antenna 10 for each of the plurality of antennas 10 and outputs information on the arrival angle at which the received radio wave has arrived. The mobile position estimation unit 30 determines whether the mobile terminal 50 is present in the vehicle interior or outside the vehicle interior based on the information on the arrival angles of the plurality of antennas 10.

In the present embodiment, the transmission boundary surface 12 is a window glass that separates the inside of the vehicle and the outside of the vehicle. The antenna 10 is arranged on the vehicle interior side of the window glass 12. The first antenna 10a is arranged adjacent to the windshield 12a on the vehicle interior side of the windshield 12a provided on the front surface of the vehicle interior 3. The second antenna 10b is arranged adjacent to the right side glass 12b on the vehicle interior side of the right side glass 12b provided on the right side of the vehicle interior 3. The third antenna 10c is arranged adjacent to the left side glass 12c on the vehicle interior side of the left side glass 12c provided on the left side of the vehicle interior 3. The fourth antenna 10d is arranged adjacent to the rear glass 12d on the vehicle interior side of the rear glass 12d provided on the rear surface of the vehicle interior 3. Other boundary surfaces such as the upper surface of the vehicle interior 3 and the lower surface of the vehicle interior 3 not provided with the window glass are covered with an iron plate so that radio waves do not pass therethrough.

Each antenna 10 and each transmission boundary surface 12 may be arranged adjacent to each other, regardless of whether or not there is a gap between each antenna 10 and each transmission boundary surface 12. good. The gap may be set to such an extent that the mobile terminal 50 is not inserted between the antenna 10 and the transmission boundary surface 12 in normal use, and may be set to, for example, 1 cm or less. It should be noted that each antenna 10 may be arranged on the outside of the vehicle interior of the transmission boundary surface 12 adjacent to the transmission boundary surface 12.

In this way, since each antenna 10 is arranged adjacent to each transmission boundary surface 12, each antenna regardless of whether the received radio wave is a reflected wave reflected in the vehicle interior or a direct wave. Based on the information of the arrival angle of 10, whether the radio wave received by the antenna 10 is a radio wave transmitted through the transmission boundary surface 12 from the outside of the vehicle interior to the vehicle interior or a radio wave transmitted through the transmission boundary surface 12 from the vehicle interior to the outside of the vehicle interior. It can be detected with high accuracy. Therefore, regardless of the direct wave and the reflected wave, it is possible to accurately determine whether the mobile terminal 50 exists in the vehicle interior or outside the vehicle interior.

<Detailed configuration of antenna 10>
Each antenna 10 has a plurality of antenna elements arranged at intervals on the linear axis 11c. In the present embodiment, as shown in FIG. 4, each antenna 10 has two antenna elements 11a and 11b arranged at intervals D on the linear axis 11c. The linear axis 11c is attached to the vehicle so that the antenna 10 extends along the normal direction 13 of the transmission boundary surface 12 in which the antenna 10 is arranged adjacently. Ideally, the linear axis 11c should be parallel to the normal direction 13. However, since it is rare that the mobile terminal 50 is located close to the transmission boundary surface 12, for example, the linear axis 11c may be tilted within a range of 0 to 10 degrees with respect to the normal direction 13. .. The distance D between the two antenna elements 11a and 11b is set to the wavelength λ / 2 or less of the radio wave to be received.

When each antenna 10 is configured and arranged in this way, the received radio wave arrives from the outside of the vehicle interior to the inside of the vehicle through the transmission boundary surface 12 by calculating the arrival angle θ of the received radio wave with respect to the linear axis 11c. It is possible to accurately determine whether the radio wave has arrived from the inside of the vehicle to the outside of the vehicle.

<Calculation method of arrival angle θ>
The wireless communication unit 20 calculates the arrival angle θ of the received radio wave with respect to the linear axis 11c based on the phase difference or the time difference between the radio wave signals received by the plurality of antenna elements provided in one antenna 10. As shown in FIG. 5, when the radio wave arrives at an angle θ with respect to the linear axis 11c, the distance at which the radio wave propagates from the mobile terminal 50, which is the transmission source of the radio wave, to the antenna elements 11a and 11b. A distance difference P is generated between them. This distance difference P is observed as the phase difference Δφ of the radio waves received at the same time by the first antenna element 11a and the second antenna element 11b. The wireless communication unit 20 measures this phase difference Δφ from the waveform of the received radio wave. The relationship of Eq. (1) holds between the phase difference Δφ and the arrival angle θ.
P = D · cos θ = Δφ · λ / (2π) ・ ・ ・ (1)

Therefore, the wireless communication unit 20 calculates the arrival angle θ by using the equation (2). As can be seen from the equation (2), the mapping from the phase difference Δφ to the arrival angle θ is set to D <λ / 2 so as to be 1: 1 from 0 to π (180 degrees). ..
θ = cos ^-1 {Δφ ・ λ / (2πD)} ・ ・ ・ (2)

Alternatively, the wireless communication unit 20 measures the time difference ΔT between the radio wave received by the first antenna element 11a and the radio wave received by the second antenna element 11b. The time difference ΔT at which the phase of the received radio wave of the first antenna element 11a and the phase of the received radio wave of the second antenna element 11b are the same is measured. The relationship of Eq. (3) holds between the time difference ΔT and the arrival angle θ. Here, C is the speed of light.
P = D · cos θ = ΔT · C ・ ・ ・ (3)

Therefore, the wireless communication unit 20 may calculate the arrival angle θ by using the equation (4).
θ = cos ^-1 (ΔT ・ C / D) ・ ・ ・ (4)

<Judgment of the inside or outside of the vehicle based on the arrival angle θ>
The portable position estimation unit 30 compares the arrival angle information with the determination threshold value for each of the plurality of antennas 10, and the received radio wave causes the transmission boundary surface 12 in which the antennas 10 are arranged adjacent to each other from the inside of the vehicle to the outside of the vehicle. It is determined whether the vehicle has penetrated or has penetrated into the vehicle interior from outside the vehicle interior.

In the present embodiment, as shown in FIG. 6, the arrival angle θ is an angle with respect to the linear axis 11c, and the direction in which the received radio wave arrives has the position of the antenna 10 as the apex 14a and the linear axis 11c as the rotation axis 14b. Then, the angle with the rotation axis 14b is within the range of the side surface 14d of the cone formed from the bus 14c which is the arrival angle θ. The linear axis 11c is arranged so as to extend toward the vehicle interior side along the normal direction 13 of the transmission boundary surface 12. Therefore, when the arrival angle θ is in the range of 0 to 90 degrees, the cone exists on the vehicle interior side with respect to the transmission boundary surface 12, and the arrival angle θ is in the range of 90 degrees to 180 degrees. There is a cone on the outside of the passenger compartment.

The portable position estimation unit 30 receives radio waves from the antenna 10 based on whether the arrival angle θ is in the range of 0 to 90 degrees or 90 degrees to 180 degrees for each of the plurality of antennas 10. Determines whether the permeation boundary surface 12 arranged adjacent to the vehicle has penetrated from the inside of the vehicle to the outside of the vehicle or from the outside of the vehicle to the inside of the vehicle. If the linear axis 11c is defined to be directed toward the outside of the vehicle interior, the angle range corresponding to the outside of the vehicle interior and the angle range corresponding to the inside of the vehicle interior are opposite to each other.

According to this configuration, a simple antenna 10 provided with only two antenna elements is arranged adjacent to the transmission boundary surface 12, and the linear axis 11c extends along the normal direction 13 of the transmission boundary surface 12. By arranging the antennas in such a manner and determining whether the calculated arrival angle θ is in the range of 0 to 90 degrees or 90 degrees to 180 degrees, the transmission direction of the received radio wave can be accurately determined. ..

Then, the mobile position estimation unit 30 determines whether the mobile terminal 50 is present in the vehicle interior or outside the vehicle interior based on the determination results of the transmission directions of the plurality of antennas.

In the present embodiment, when the mobile position estimation unit 30 determines that all of the plurality of antennas have transmitted from the vehicle interior to the outside of the vehicle interior, the mobile terminal 50 determines that the mobile terminal 50 exists in the vehicle interior, and one or more of them. When it is determined that the antenna is transmitted from the outside of the vehicle interior to the inside of the vehicle interior, it is determined that the mobile terminal 50 exists outside the vehicle interior.

As shown in FIG. 7, when the mobile terminal 50 is in the vehicle interior, the received radio wave of each antenna is a transmission boundary surface 12 provided with each antenna 10 regardless of whether it is a direct wave or a reflected wave. Is transmitted from the inside of the vehicle to the outside of the vehicle. Therefore, when it is determined that all the antennas are transmitted from the vehicle interior to the outside of the vehicle interior, it can be accurately determined that the mobile terminal 50 is present in the vehicle interior. Actually, since there are antennas that cannot be communicated by NLOS (radio waves do not reach), all antennas that have received radio waves are determined.

On the other hand, as shown in FIG. 8, when the mobile terminal 50 is outside the vehicle interior, the transmitted radio wave of the mobile terminal 50 is transmitted from the outside of the vehicle interior to the inside of the vehicle through a specific transmission boundary surface 12 close to the mobile terminal 50. The direct wave or the reflected wave reflected in the vehicle interior penetrates the other transmission boundary surface 12 from the vehicle interior to the outside of the vehicle interior. Therefore, when the mobile terminal 50 is outside the vehicle interior, the received radio waves of one or more antennas pass through the transmission boundary surface 12 from the outside of the vehicle interior to the inside of the vehicle. On the other hand, even when the mobile terminal 50 is outside the vehicle interior, the received radio waves of the remaining antennas pass through the transmission boundary surface 12 from the vehicle interior to the outside of the vehicle interior. Therefore, when it is determined that one or more antennas are transmitted from the outside of the vehicle interior to the inside of the vehicle interior, it can be accurately determined that the mobile terminal 50 exists outside the vehicle interior.

If the wireless communication unit 20 can receive a plurality of received radio waves of a direct wave and a reflected wave for each antenna, the wireless communication unit 20 calculates the arrival angle of the received radio wave having the strongest reception intensity among the plurality of received radio waves. When one antenna simultaneously receives multiple radio waves of direct wave and reflected wave, in the case of UWB, it is a pulsed signal, so by separating the signal that first arrived from the received signal, only the direct wave is processed. Will be done. In the case of Bluetooth Low Energy, if the difference between the propagation distances of the direct wave and the reflected wave is short, multiple radio waves are combined and an error occurs. Therefore, UWB is more advantageous in a multipath environment.

<Variations of antenna arrangement>
9 to 11 show variations of the vehicle interior 3 and the antenna arrangement. In each case, the passenger compartment 3 is modeled as a three-dimensional object composed of planes. The hatched plane is a non-transmissive boundary surface that blocks radio waves, and the non-hatched plane is a transmission boundary surface. .. FIG. 9 shows a case where a part of one plane is shielded, and FIGS. 10 and 11 show an example in which a part of the plane is inclined. In FIG. 10, one side surface is a non-transmissive boundary surface, and no antenna is provided, so that a total of three antennas are provided. FIG. 10 shows a case where the plane is inclined like a windshield. As shown in these figures, one antenna 10 is arranged adjacent to each transmission boundary surface. The linear axis 11c of each antenna 10 is attached to the vehicle so that the antenna 10 extends along the normal direction 13 of the transmission boundary surface 12 arranged adjacent to the antenna 10.

2. 2. Embodiment 2
Next, the position estimation system according to the second embodiment will be described. The description of the same components as those in the first embodiment will be omitted. The basic configuration of the position estimation system according to the present embodiment is the same as that of the first embodiment, but the mobile terminal 50 uses the information of the distance R between the mobile terminal and the antenna in addition to the information of the arrival angle. The point of estimating the position of is different from that of the first embodiment.

<Calculation of distance R>
The wireless communication unit 20 processes the radio wave signal received by the antenna 10 for each of the plurality of antennas 10 and outputs information on the distance R between the mobile terminal 50 and the antenna 10.

An example of a method of calculating the distance R between the mobile terminal 50 and the antenna 10 based on the propagation time TOF (Time Of Flight) by communication will be described. The wireless communication unit 20 processes radio signals transmitted and received between the antenna 10 and the antenna 51 of the mobile terminal for each of the plurality of antennas 10, and outputs information on the distance R between the mobile terminal 50 and the antenna 10. .. As shown in the sequence diagram of FIG. 12, the wireless communication unit 20 transmits radio waves from the antenna 10. The transmitted radio wave may include a command to transmit a reply radio wave. The mobile wireless communication unit 52 of the mobile terminal 50 receives the radio wave transmitted from the antenna 10 by the mobile antenna 51, processes the reception, and then transmits the reply radio wave from the mobile antenna 51. At this time, the mobile wireless communication unit 52 adds information on the time TB (referred to as the mobile processing time TB) required for the reception processing of the mobile wireless communication unit 52 to the reply radio wave. The wireless communication unit 20 receives the radio wave transmitted from the mobile antenna 51 by the antenna 10 and processes the reception. The wireless communication unit 20 measures the time TA (referred to as delay time TA) from the transmission of the radio wave from the antenna 10 to the reception of the reply radio wave. Further, the wireless communication unit 20 acquires the information of the mobile processing time TB included in the reply radio wave. Then, as shown in the equations (5) and (6), the wireless communication unit 20 calculates the propagation time TOF by dividing the time obtained by subtracting the portable processing time TB from the delay time TA by 2, and calculates the propagation time. The distance R is calculated by multiplying the TOF by the speed of light C. The delay time between the antenna 10 and the wireless communication unit 20 and the delay time between the mobile antenna 51 and the mobile wireless communication unit 52 are measured in advance and reflected in the delay time TA and the mobile processing time TB. To.
TOF = (TA-TB) / 2 ... (5)
R = TOF × C ・ ・ ・ (6)

The distance measured by either of the two antenna elements of each antenna 10 or the average value of the distances measured by the two antenna elements is used.

<Position estimation of mobile terminal 50>
The mobile position estimation unit 30 estimates the position of the mobile terminal 50 based on the arrival angle information and the distance information of the plurality of antennas. According to this configuration, not only whether the mobile terminal 50 exists inside or outside the vehicle interior, but also the detailed position of the mobile terminal 50 can be determined.

As shown in FIG. 13, in the portable terminal 50, the position of the antenna 10 is the apex 14a, the linear axis 11c is the rotation axis 14b, the angle with the rotation axis 14b is the arrival angle θ, and the length is the distance R. It is located on any of the outer circles 14f of the bottom surface 14e of the cone formed from the bus 14c.

Therefore, the portable position estimation unit 30 determines the position of the antenna 10 for each of the plurality of antennas 10 in the three-dimensional space in which the three-dimensional shape of the vehicle interior 3, the position of each antenna 10, and the direction of the linear axis 11c are preset. Is the apex, the linear axis 11c is the rotation axis 14b, the angle with the rotation axis 14b is the arrival angle θ, and the outer circumference circle 14f of the bottom surface 14e of the cone formed from the bus 14c having the length R is calculated. .. Then, the mobile position estimation unit 30 calculates a position close to the outer peripheral circle 14f of the plurality of antennas 10 as the position of the mobile terminal 50.

According to this configuration, the outer peripheral circle 14f of the bottom surface of the cone is calculated based on the arrival angle θ and the distance R of each antenna 10, and the position of the mobile terminal 50 is estimated based on the outer peripheral circle 14f of each antenna 10. be able to. Since not only the information on the distance R of each antenna 10 but also the information on the arrival angle θ is used, the estimation accuracy can be improved.

FIG. 14 shows an estimation example. The upper left figure of FIG. 14 is a schematic top view of the vehicle as viewed from above, and the front side of the vehicle is the upper side of the paper surface. The upper right view of FIG. 14 is a side view of the vehicle viewed from the right side, and the lower left view of FIG. 14 is a side view of the vehicle viewed from the rear side. The mobile terminal 50 is located diagonally rearward on the right side of the vehicle. FIG. 14 shows the outer circumference circle 14fb of the cone calculated by the detection information of the second antenna 10b on the right side and the outer circumference circle 14fd of the cone calculated by the detection information of the fourth antenna 10d on the rear side. Then, the mobile position estimation unit 30 estimates the position 2P close to the two outer circles 14fb and 14fd as the position of the mobile terminal 50. The outer circle of the cone calculated from the detection information of the third antenna 10c on the left side and the outer circle of the cone calculated from the detection information of the first antenna 10a on the front side may also be used for position estimation.

In addition, as in the example of FIG. 14, when the mobile terminal 50 determines that the mobile terminal 50 exists outside the vehicle interior, the received radio wave is transmitted from the outside of the vehicle interior to the inside of the vehicle interior through the transmission boundary surface. The position of the mobile terminal 50 may be estimated based on the arrival angle θ and the distance R of only the determined single or plurality of antennas. With such a configuration, it is possible to prevent the reflected wave reflected in the vehicle interior from being used and improve the estimation accuracy.

3. 3. Embodiment 3
Next, the position estimation system according to the third embodiment will be described. Description of the same components as in the second embodiment will be omitted. The basic configuration of the position estimation system according to the present embodiment is the same as that of the second embodiment, but the position estimation system cannot calculate the arrival angle θ and can calculate the distance. The point that the antenna 16 is further provided is different from the second embodiment.

FIG. 15 shows an example of the antenna arrangement according to the present embodiment. In this example, two distance antennas 16a and 16b are provided. The two distance antennas 16a and 16b are provided outside the vehicle interior and are not arranged adjacent to the transmission boundary surface. The first distance antenna 16a is arranged at the front end of the vehicle and is second. The distance antenna 16b is arranged at the rear end of the vehicle. The distance antenna 16 may be arranged in the vehicle interior. Further, the rear surface 12d of the vehicle interior 3 is a shielding surface, and the antenna 10 is not provided. The front surface 12a, the right surface 12b, and the left surface 12c of the vehicle interior 3 are transmission surfaces, and antennas 10 capable of calculating the arrival angle and the distance are adjacent to each other.

The distance antenna 16 has only one antenna element and can calculate the distance, but cannot calculate the arrival angle θ. The wireless communication unit 20 processes the radio wave signal received by the distance antenna 16 for each distance antenna 16 and outputs the distance between the mobile terminal 50 and the distance antenna 16. Since the distance is calculated based on the propagation time TOF as in the second embodiment, the description thereof will be omitted. In the present embodiment, one wireless communication unit 20d and 20e are provided for each distance antenna 16.

Similar to the first embodiment, the mobile position estimation unit 30 has the mobile terminal 50 inside or outside the vehicle interior based on the information on the arrival angles of the plurality of antennas 10 that can calculate the arrival angle. Is determined.

Further, as in the second embodiment, the portable position estimation unit 30 rotates a linear axis with the position of the antenna 10 as the apex for each of the plurality of antennas 10 capable of calculating the arrival angle and the distance in the three-dimensional space. The outer circle of the bottom surface of the cone formed from the bus whose axis is the angle of arrival and whose length is the distance is calculated.

The portable position estimation unit 30 determines the position of the distance antenna 16 for each of the single or multiple distance antennas 16 in a three-dimensional space in which the three-dimensional shape of the vehicle interior 3 and the position of each distance antenna 16 are preset. Calculates a sphere centered on and with the distance as the radius.

Then, the mobile position estimation unit 30 calculates a plurality of outer peripheral circles and a position close to a single or a plurality of spherical surfaces as the position of the mobile terminal 50. According to this configuration, the position estimation accuracy of the mobile terminal 50 can be easily improved by adding a simple distance antenna 16. Further, when it is determined that the antenna 10 has a large error in the information on the arrival angle, only the information on the distance is used. In this case, a spherical surface centered on the position of the antenna 10 and a radius of the distance R is used for position estimation. As a result, it is possible to suppress the mixing of position estimation errors.

<Example of diversion>
In each of the above embodiments, the case where Bluetooth (registered trademark) Low Energy or Ultra Wide Band communication method is used as the communication method has been described as an example. However, as the communication method, another communication method capable of calculating the arrival angle may be used.

In each of the above embodiments, the case where the mobile terminal 50 is a mobile information terminal including a smartphone has been described as an example. However, the mobile terminal 50 may be any mobile terminal as long as it is possessed by the user of the vehicle and can communicate with it.

In each of the above embodiments, the case where the antenna 10 includes two antenna elements has been described as an example. However, the antenna 10 may be an antenna having any configuration as long as it can detect the arrival angle of the received radio wave.

In each of the above embodiments, the case where the plurality of wireless communication units 20 and the mobile position estimation unit 30 are separate bodies has been described as an example. However, the plurality of wireless communication units 20 and the mobile position estimation unit 30 are integrated devices, or the plurality of wireless communication units 20 are integrated devices and are separate from the mobile position estimation unit 30. It may be configured by any combination such as.

Although the present application describes various exemplary embodiments and examples, the various features, embodiments, and functions described in one or more embodiments are applications of a particular embodiment. It is not limited to, but can be applied to embodiments alone or in various combinations. Therefore, innumerable variations not exemplified are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

θ Arrival angle, 1 vehicle, 3 cabins, 10 antennas, 11c linear axis, 12 transmission boundary surface (boundary surface), 13 normal direction, 14a apex, 14b rotation axis, 14c bus, 14e bottom surface, 14f outer circle, 16 Distance antenna, 20 wireless communication unit, 30 mobile position estimation unit, 50 mobile terminal, R distance

Claims (11)

Multiple antennas attached to the vehicle that receive radio waves transmitted from the mobile terminal owned by the user of the vehicle,
For each of the plurality of antennas, a wireless communication unit that processes the radio wave signal received by the antenna and outputs information on the arrival angle at which the received radio wave arrives.
A mobile position estimation unit for determining whether the mobile terminal exists in the vehicle interior or outside the vehicle interior based on the information of the arrival angle of the plurality of antennas is provided.
Each of the plurality of antennas is arranged adjacent to each of the plurality of boundary surfaces through which radio waves can pass , in the normal direction of the respective boundary surfaces, so as to separate the inside and outside of the vehicle interior .
The portable position estimation unit compares the arrival angle information and the determination threshold value for each of the plurality of antennas, and the received radio wave causes the boundary surface on which the antennas are arranged adjacent to the vehicle interior to the outside of the vehicle interior. Determine whether it has penetrated or penetrated from outside the vehicle interior into the vehicle interior.
A mobile terminal position estimation system for a vehicle that determines whether the mobile terminal exists in the vehicle interior or outside the vehicle interior based on the determination results of the transmission directions of the plurality of antennas. When the mobile position estimation unit determines that all of the plurality of antennas have penetrated from the vehicle interior to the outside of the vehicle interior, the mobile position estimation unit determines that the mobile terminal exists in the vehicle interior, and the vehicle with respect to one or more of the antennas. The mobile terminal position estimation system for a vehicle according to claim 1 , wherein when it is determined that the mobile terminal has penetrated into the vehicle interior from the outside of the vehicle, it is determined that the mobile terminal exists outside the vehicle interior. Multiple antennas attached to the vehicle that receive radio waves transmitted from the mobile terminal owned by the user of the vehicle,
For each of the plurality of antennas, a wireless communication unit that processes the radio wave signal received by the antenna and outputs information on the arrival angle at which the received radio wave arrives.
A mobile position estimation unit for determining whether the mobile terminal exists in the vehicle interior or outside the vehicle interior based on the information of the arrival angle of the plurality of antennas is provided.
Each of the plurality of antennas is arranged adjacent to each of the plurality of boundary surfaces through which radio waves can pass, in the normal direction of the respective boundary surfaces, so as to separate the inside and outside of the vehicle interior.
Each of the plurality of antennas has a plurality of antenna elements arranged at intervals on a linear axis, and the linear axis extends along the normal direction of the boundary surface on which the antennas are arranged adjacent to each other. As such, a mobile terminal position estimation system for vehicles attached to a vehicle . The mobile terminal position estimation system for a vehicle according to claim 3 , wherein the plurality of antenna elements of the antenna are two antenna elements. The wireless communication unit calculates the arrival angle of the received radio wave with respect to the linear axis toward the vehicle interior based on the phase difference or the time difference between the radio wave signals received by the plurality of antenna elements for each of the plurality of antennas. death,
The portable position estimation unit receives radio waves from the antennas based on whether the arrival angle is in the range of 0 to 90 degrees or 90 degrees to 180 degrees for each of the plurality of antennas. Determines whether the boundary surface adjacent to the vehicle has penetrated from the inside of the vehicle to the outside of the vehicle or from the outside of the vehicle to the inside of the vehicle.
The mobile terminal position estimation system for a vehicle according to claim 3 or 4 , wherein it is determined whether the mobile terminal is present in the vehicle interior or outside the vehicle interior based on the determination results of the transmission directions of the plurality of antennas. The wireless communication unit processes the radio wave signal received by the antenna for each of the plurality of antennas, and outputs information on the distance between the mobile terminal and the antenna.
The mobile phone for a vehicle according to any one of claims 1 to 5 , wherein the mobile position estimation unit estimates the position of the mobile terminal based on the information on the arrival angle of the plurality of antennas and the information on the distance. Terminal position estimation system. Multiple antennas attached to the vehicle that receive radio waves transmitted from the mobile terminal owned by the user of the vehicle,
For each of the plurality of antennas, a wireless communication unit that processes the radio wave signal received by the antenna and outputs information on the arrival angle at which the received radio wave arrives.
A mobile position estimation unit for determining whether the mobile terminal exists in the vehicle interior or outside the vehicle interior based on the information of the arrival angle of the plurality of antennas is provided.
Each of the plurality of antennas is arranged adjacent to each of the plurality of boundary surfaces through which radio waves can pass, in the normal direction of the respective boundary surfaces, so as to separate the inside and outside of the vehicle interior.
Each of the plurality of antennas has a plurality of antenna elements arranged at intervals on a linear axis, and the linear axis extends along the normal direction of the boundary surface on which the antennas are arranged adjacent to each other. So attached to the vehicle,
The wireless communication unit calculates the arrival angle of the received radio wave with respect to the linear axis for each of the plurality of antennas based on the phase difference or the time difference between the radio wave signals received by the plurality of antenna elements.
For each of the plurality of antennas, the radio wave signal received by the antenna is processed, and the distance between the mobile terminal and the antenna is output.
For each of the plurality of antennas, the portable position estimation unit has the position of the cone as the apex, the linear axis as the rotation axis, the angle with the rotation axis is the arrival angle, and the length is the distance. Calculate the outer circle of the bottom of the cone formed from a certain bus,
A mobile terminal position estimation system for a vehicle that calculates the position of a plurality of antennas near the outer peripheral circle as the position of the mobile terminal. Further equipped with a single or a plurality of distance antennas capable of calculating the distance without being able to calculate the arrival angle.
The portable position estimation unit calculates the outer peripheral circle of the bottom surface of the cone for each of the plurality of antennas capable of calculating the arrival angle and the distance, and for each of the single or the plurality of distance antennas, the said. Calculate a spherical surface centered on the position of the distance antenna and using the distance as the radius.
The mobile terminal position estimation system for a vehicle according to claim 7 , wherein a plurality of the outer peripheral circles and a single or a plurality of positions close to the spherical surface are calculated as the positions of the mobile terminals. The vehicle portable according to any one of claims 1 to 8 , wherein the boundary surface is a window glass that separates the inside of the vehicle and the outside of the vehicle, and the antenna is arranged on the vehicle interior side of the window glass. Terminal position estimation system. The vehicle mobile terminal position estimation according to any one of claims 1 to 9 , wherein the communication method between the mobile terminal and the plurality of antennas is Bluetooth (registered trademark) Low Energy or Ultra Wide Band communication method. system. The mobile terminal position estimation system for a vehicle according to any one of claims 1 to 10, wherein the mobile terminal is a mobile information terminal including a smartphone.

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