JP2016200478A - Position estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position estimation device capable of accurately estimating the position of a portable terminal with respect to a vehicle even in a multipath environment.SOLUTION: An on-vehicle communication unit 1 includes: a first array antenna 11A for receiving a radio wave from a portable terminal; a first arrival direction estimation section 13A for estimating an arrival direction of the radio wave received by the first array antenna 11A; a reflection surface information acquisition section 15 for acquiring reflection surface information; and a position estimation section 16 for estimating the position of the portable terminal 200. The reflection surface information is information indicating the position of a reflection surface that exists around a vehicle and can reflect the radio wave from the portable terminal 200. Based on the reflection surface information, the position estimation section 16 determines whether the arrival direction estimated by the first arrival direction estimation section 13A is a direct arrival direction derived from a direct wave or a reflection arrival direction derived from the reflection wave. Then, the direction in which the portable terminal 200 is present is estimated based on the result of determination.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position estimation device that estimates the position of a mobile terminal with respect to a vehicle by an arrival direction estimation method.

  2. Description of the Related Art Conventionally, a position estimation system that estimates the position of a mobile terminal with respect to a vehicle by a well-known arrival direction estimation method in cooperation with an in-vehicle device (referred to as a position estimation device) mounted on the vehicle and a mobile terminal carried by a user. Various proposals have been made.

  For example, the portable terminal in the position estimation system disclosed in Patent Document 1 transmits a UHF band search signal based on a user operation for estimating the position of the vehicle. On the other hand, the position estimation device corresponding to the mobile terminal receives the search signal transmitted from the mobile terminal by the array antenna, and analyzes the reception mode (phase and amplitude) of the signal received by the array antenna, thereby Is estimated. Moreover, this position estimation apparatus estimates the distance of the portable terminal with respect to the vehicle from the received signal strength of the received search signal.

  And the position estimation apparatus estimates the relative position of the portable terminal with respect to the vehicle from the arrival direction and the distance. As a method for estimating the arrival direction of radio waves, a known arrival direction estimation method such as a MUSIC (Multiple Signal Classification) method can be employed.

JP 2012-68100 A

  A radio communication radio wave, for example, a 2.4 GHz band radio wave is easily reflected by the body (that is, a metal plate) of another vehicle, and has a characteristic of being greatly attenuated by superposition of a human body, water, and the reflected wave.

  Therefore, for example, when the other vehicle is parked around the own vehicle, the own vehicle exists in an environment (so-called multipath environment) in which the radio wave transmitted from the mobile terminal is highly likely to be reflected and reached. In some cases, the position estimation device may detect the direction in which the reflected wave is arriving as the arrival direction of the radio wave.

  And if a position estimation apparatus misrecognizes that the arrival direction of a reflected wave is a direction in which a portable terminal exists, it will estimate the position of a portable terminal in the wrong position. That is, in the multipath environment, the estimation accuracy of the position of the mobile terminal tends to be lowered.

  The present invention has been made based on this situation, and an object of the present invention is to provide a position estimation device capable of estimating the position of a mobile terminal with respect to a vehicle with higher accuracy even in a multipath environment. .

  To achieve the object, the present invention provides an array antenna (11, 11A, 11B) including a plurality of antenna elements mounted on a vehicle and receiving radio waves from a portable terminal carried by the user of the vehicle, and an array antenna. A direction-of-arrival estimation unit (13, 13A, 13B) that estimates the direction of arrival of the received radio wave, and a position estimation unit (16) that estimates the position of the mobile terminal relative to the vehicle based on the estimation result of the direction-of-arrival estimation unit; A reflection surface position specifying unit that detects an object existing around the vehicle and specifies a position and an angle of the reflection surface, which is a surface that can reflect radio waves from the mobile terminal, based on the position of the detected object. (2), and the position estimation unit determines whether or not the reflection surface specified by the reflection surface position specification unit exists in the arrival direction estimated by the arrival direction estimation unit. When the direct arrival direction is the direction of arrival that is the resident city direction exists, and estimates the position of the portable terminal to the vehicle on the basis of the direct arrival direction.

  In the above configuration, the position estimation unit determines whether there is a reflection surface in the arrival direction estimated by the arrival direction estimation unit based on the position of the reflection surface around the vehicle specified by the reflection surface position specification unit. judge.

  The presence of a reflection surface in the arrival direction means that the arrival direction is a direction in which a reflected wave arrives (referred to as a reflection arrival direction). And there is a high possibility that the mobile terminal does not exist in the direction in which the reflected wave arrives.

  On the other hand, the absence of a reflecting surface in the arrival direction means that the arrival direction is a direction in which a radio wave transmitted from the mobile terminal is directly received. That is, the direct arrival direction, which is the arrival direction in which no reflection surface exists, represents the direction in which the mobile terminal exists (referred to as the terminal direction).

  That is, in the above configuration, the position estimation unit identifies whether the arrival direction estimated by the arrival direction estimation unit is a direct arrival direction corresponding to the terminal direction based on the position of the reflection surface. Thereby, it can suppress misjudging that the reflection arrival direction is a terminal direction.

  Therefore, according to the above configuration, it is possible to suppress the possibility of erroneously determining that the direction in which the reflected wave arrives is the terminal direction, and as a result, the position of the mobile terminal with respect to the vehicle more accurately even in a multipath environment. Can be estimated.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

1 is a block diagram showing a schematic configuration of a position estimation system 1000. FIG. It is a block diagram which shows schematic structure of 12 A of 1st receiving parts, and 13 A of 1st arrival direction estimation parts. FIG. 5 is a conceptual diagram for explaining the operation of a position estimation unit 16. It is a conceptual diagram for demonstrating the effect of embodiment. 5 is a graph showing the relationship between a search azimuth angle θ and combined received power in the situation shown in FIG. 10 is a block diagram showing a schematic configuration of a position estimation unit 16 in Modification 1. FIG. It is a conceptual diagram for demonstrating the action | operation of the position estimation part 16 in the modification 1. FIG. It is a block diagram which shows the other aspect of the vehicle-mounted communication apparatus. FIG. 11 is a conceptual diagram for explaining an effect of the configuration of Modification 1.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a schematic configuration of a position estimation system 1000 to which the position estimation apparatus according to the present embodiment is applied. As shown in FIG. 1, the position estimation system 1000 includes an in-vehicle system 100 mounted on a vehicle and a portable terminal 200 carried by a user.

  The in-vehicle system 100 and the mobile terminal 200 perform communication based on a predetermined short-range wireless communication standard in which a communication range is, for example, about several tens of meters at the maximum (referred to as short-range communication). The mobile terminal 200 only needs to have the above-described short-range communication function. For example, a mobile phone such as a smartphone can be used as the mobile terminal 200. Of course, the mobile terminal 200 is not limited to a mobile phone, and may be a tablet terminal, a wearable device, a portable music player, a portable game machine, or the like.

  As the near field communication standard here, for example, Bluetooth Low Energy (Bluetooth is a registered trademark), Wi-Fi (registered trademark), ZigBee (registered trademark), or the like can be adopted.

  Moreover, the communication standard used for communication between the in-vehicle system 100 and the portable terminal 200 may be a mode that implements communication based on another communication standard, and is adopted in, for example, a well-known keyless entry system or smart entry system. It may be what has been done.

  Hereinafter, an example of the configuration of the mobile terminal 200 and the in-vehicle system 100 will be described more specifically. For convenience, a vehicle on which the in-vehicle system 100 is mounted is referred to as a host vehicle.

<Configuration of mobile terminal 200>
As illustrated in FIG. 1, the mobile terminal 200 includes an antenna 210, a transmission unit 220, and a communication controller 230. The antenna 210 converts the signal input from the transmission unit 220 into a radio wave of a frequency band (for example, 2.4 GHz band) used for short-range communication with the in-vehicle system 100 and radiates it to space.

  The transmission unit 220 amplifies and frequency-converts the signal input from the communication controller 230 and outputs the signal to the antenna 210. The communication controller 230 controls the operation on the mobile terminal 200 side in short-range communication between the mobile terminal 200 and the in-vehicle system 100. For example, the communication controller 230 generates a baseband signal corresponding to data to be transmitted to the in-vehicle system 100 and outputs the baseband signal to the transmission unit 220. Thereby, the mobile terminal 200 can transmit a signal indicating desired data to the in-vehicle system 100.

  The case where the portable terminal 200 transmits a signal to the in-vehicle system 100 may be a case where a user operation for knowing the position of the host vehicle is received via a switch (not shown), for example.

<Configuration of in-vehicle system 100>
The in-vehicle system 100 includes an in-vehicle communication device 1 and a reflection surface specifying device 2 as shown in FIG. The in-vehicle communication device 1 receives a signal transmitted from the mobile terminal 200 and specifies the position of the mobile terminal 200 with respect to the host vehicle. The in-vehicle communication device 1 corresponds to the position estimation device described in the claims. The in-vehicle communication device 1 and the reflection surface specifying device 2 are connected to each other via a LAN (Local Area Network) so that they can communicate with each other.

  The in-vehicle communication device 1 includes a first array antenna 11A, a second array antenna 11B, a first receiving unit 12A, a second receiving unit 12B, a first arrival direction estimation unit 13A, and a second arrival direction estimation unit as finer constituent elements. 13B, the memory | storage part 14, the reflective surface information acquisition part 15, and the position estimation part 16 are provided. The first receiving unit 12A, the second receiving unit 12B, the first arrival direction estimation unit 13A, the second arrival direction estimation unit 13B, the reflection surface information acquisition unit 15, and the position estimation unit 16 are each realized by hardware. It may be realized by software.

  The first array antenna 11A is a kind of directional antenna, and includes a plurality of antenna elements arranged in a line (or plane) at a predetermined interval. The plurality of antenna elements constituting the first array antenna 11A are each connected to the first receiver 12A.

  Here, as an example, the antenna elements are arranged in a line so that the arrangement direction thereof is parallel to the vehicle width direction at a position where the vehicle is appropriately designed. That is, the first array antenna 11A is a linear array antenna disposed in parallel with the vehicle width direction. For convenience, the direction orthogonal to the arrangement direction of the antenna elements constituting the first array antenna 11A on the horizontal plane is defined as 0 °. Each antenna element itself may be a linear antenna or a planar antenna. The number of antenna elements is N. N is a natural number of 2 or more.

  Each antenna element receives radio waves in a frequency band used for short-range communication with the mobile terminal 200, converts the radio waves into an electrical signal, and outputs the electrical signal to the first receiver 12A. The received signal of each antenna element has a phase difference corresponding to the interval between the antenna elements and the arrival direction of the radio wave. Based on the phase difference, the first arrival direction estimation unit 13A described later estimates the arrival direction of the received radio wave.

  The directivity of the first array antenna 11A is dynamically changed by a first arrival direction estimation unit 13A described later. The directivity of the first array antenna 11A can be changed from −90 ° to + 90 ° with reference to the 0 ° direction. From the movable range of the directivity of the first array antenna 11A and the installation position, a range in which the first array antenna 11A can receive a signal from the mobile terminal 200 (a receivable range) is determined.

  The second array antenna 11B has the same configuration and function as the first array antenna 11A. When the first array antenna 11A and the second array antenna 11B are not distinguished from each other, they are simply referred to as the array antenna 11.

  The first array antenna 11A and the second array antenna 11B are installed in the host vehicle so as to have a predetermined interval in the vehicle width direction (or vehicle front-rear direction) so that the respective receivable ranges substantially coincide. Here, as an example, it is assumed that at the front end portion of the host vehicle, the vehicle is disposed at a position that is a fixed distance (for example, 0.2 m) from the center in the vehicle width direction. In addition, the receivable range of each array antenna 11 is a range from −90 ° to + 90 ° in the horizontal direction from the front end of the host vehicle with the front direction of the host vehicle being the 0 ° direction.

  The installation positions of the first array antenna 11A and the second array antenna 11B are not limited to this. For example, the vehicle may be disposed at the left and right corner portions of the front bumper of the host vehicle, or may be disposed at the left and right corner portions of the rear bumper. Furthermore, it may be installed in other places. Data (installation position data) indicating the installation position of each array antenna 11 in the host vehicle is stored in the storage unit 14. The storage unit 14 is a non-volatile storage medium such as a ROM or a flash memory.

  The first receiving unit 12A converts signals received by the antenna elements of the first array antenna 11A into digital signals (that is, analog-digital conversion), and outputs the digital signals to the first arrival direction estimating unit 13A. The first receiver 12A includes a high-frequency filter for removing frequency components outside the specified band from the received signal, a low-noise amplifier that amplifies the signal, a frequency converter that converts the carrier frequency band to the intermediate frequency band, and the like. You may have.

  The second receiving unit 12B has the same configuration and function as the first receiving unit 12A, converts the signal received by the second array antenna 11B into a digital signal, and sends it to the second arrival direction estimating unit 13B. Output. When the first receiving unit 12A and the second receiving unit 12B are not distinguished, they are described as the receiving unit 12.

  The first arrival direction estimation unit 13A uses a known arrival direction estimation method and analyzes the reception signal of each antenna element included in the first array antenna 11A, so that the arrival direction of the radio wave received by the first array antenna 11A. Is estimated. Here, as an example, the first arrival direction estimation unit 13A estimates the arrival direction by a known beamformer method.

  That is, the first arrival direction estimation unit 13A scans the main lobe (main beam) of the first array antenna 11A by adjusting the complex weight to be applied to each antenna element, and synthesizes the reception signal of each antenna element. A direction in which the output power is greater than or equal to a predetermined threshold is searched. The direction in which the combined output power of the received signal of each antenna element is equal to or greater than a predetermined threshold corresponds to the arrival direction of the radio wave. The search range of the main beam scanning range is from −90 ° to + 90 ° with a direction (0 °) orthogonal to the arrangement direction of the antenna elements constituting the first array antenna 11A as a reference (0 °). The complex weight is an element for adjusting the phase and amplitude of the received signal.

  As a functional block for estimating the direction of arrival by the beamformer method outlined above, the first direction-of-arrival estimation unit 13A includes a complex weighting unit 131A and a weighting command unit 132A as shown in FIG. And a correlation calculation unit 133A and an arrival direction acquisition unit 134A. The complex weight giving unit 131A gives the complex weight instructed by the weighting command unit 132A to the reception signal of each antenna element. The complex weighting unit 131A includes an amplitude adjuster that adjusts the amplitude of the received signal of each antenna element and a phase adjuster that adjusts the phase of the received signal of each antenna element.

  The weighting command unit 132A adjusts the complex weight to be given by the complex weight giving unit 131A. The complex weight to be assigned by the complex weight assigning unit 131A is determined according to an angle (searched azimuth angle) that is sequentially set (changed) in a search range from −90 ° to + 90 °. The search azimuth corresponds to the direction in which the main lobe is directed. When the complex weight added to each antenna element when the search azimuth is θ is expressed as W (θ), the relationship between the search azimuth θ and the complex weight W (θ) may be set in advance. Note that the search azimuth angle θ may be changed by a certain angle in the search range. Here, the main lobe is scanned in the search range by increasing by 2 ° from −90 ° to + 90 °.

  The correlation calculation unit 133A calculates combined output power obtained by combining the reception signals multiplied by the complex weights. The combined output power when the search azimuth angle is a certain angle θ corresponds to the received power at the first array antenna 11A when the main lobe is directed in the direction θ.

  The arrival direction acquisition unit 134A acquires a direction in which the combined output power is equal to or greater than a predetermined threshold as the arrival direction. The arrival direction corresponds to a candidate for a direction (terminal direction) in which the mobile terminal 200 exists as viewed from the first array antenna 11A. Since the direction in which the reflected wave arrives is also detected as the arrival direction, the arrival direction is not necessarily the terminal direction. The information indicating the arrival direction acquired by the arrival direction acquisition unit 134A, that is, the terminal direction candidate is referred to as first arrival direction information for convenience. The first arrival direction information is provided to the position estimation unit 16.

  Here, as an example, the first arrival direction estimation unit 13A acquires the arrival direction by the beamformer method, but is not limited thereto. For example, the well-known Capon method may be used. Furthermore, instead of using the basic principle of scanning the main lobe (so-called beam scanning), a method of estimating the arrival direction by scanning the null point (so-called null scanning) may be adopted. There are a minimum norm method, a MUSIC (Multiple Signal Classification) method, and the like as an arrival direction estimation method based on null scanning. In addition, ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) or the like may be employed.

  The second arrival direction estimation unit 13B has the same configuration and function as the first arrival direction estimation unit 13A. That is, the second arrival direction estimation unit 13B scans the main lobe of the second array antenna 11B by adjusting the complex weight for each antenna element included in the second array antenna 11B, and receives the signal at the second array antenna 11B. The direction in which the power is greater than or equal to a predetermined threshold is acquired as the arrival direction. Note that the received power at the second array antenna 11B corresponds to the combined output power obtained by combining the received signals at the respective antenna elements included in the second array antenna 11B, to which complex weights are given.

  For convenience, information indicating the arrival direction acquired by the second arrival direction estimation unit 13B is referred to as second arrival direction information. Note that the first arrival direction estimation unit 13A and the second arrival direction estimation unit 13B are described as the arrival direction estimation unit 13 when they are not distinguished from each other.

  The reflection surface information acquisition unit 15 acquires reflection surface information from the reflection surface identification device 2. The reflection surface information is information representing the position of the reflection surface existing in the receivable range. This reflective surface information will be described later separately.

  The position estimation unit 16 estimates the relative position of the mobile terminal 200 with respect to the host vehicle based on the reflection surface information, the first arrival direction information, the second arrival direction information, and the installation position data stored in the storage unit 14. . Details of the position estimating unit 16 will be described later.

  The reflecting surface specifying device 2 detects a predetermined detection target existing in a predetermined range (referred to as a detection range) around the host vehicle. Further, the relative position of the detected object with respect to the host vehicle is specified.

  The detection target here includes an object (referred to as a radio wave reflector) that can reflect radio waves from the mobile terminal 200 such as a vehicle body, a metal signboard, and a metal wall. Note that it is not necessary to set all of the examples exemplified here as detection targets, and only a part (for example, the body of a vehicle) may be set as the detection target.

  The reflection surface specifying device 2 may be realized by, for example, a laser radar, a millimeter wave radar, a sonar, an in-vehicle camera, or a combination thereof. For example, the reflecting surface specifying device 2 may be realized by a combination of an in-vehicle camera and a millimeter wave radar. In such a case, a known image recognition process is performed on the image captured by the in-vehicle camera to detect a predetermined detection target, and the relative position of the object is specified based on the detection result of the millimeter wave radar. To do. At that time, by specifying the direction of the detection object from the result of the image recognition process, the position and angle of the surface that can reflect the signal from the portable terminal 200 (that is, the reflection surface) with respect to the host vehicle is specified. .

  The laser radar is present around the host vehicle by intermittently emitting the laser light to sweep and irradiate the laser light in a range of a predetermined angle in each of the horizontal direction and the height direction (that is, scan). The relative position of the object and its surface shape can be specified. Therefore, when a laser radar is employed as the reflecting surface specifying device 2, the reflecting surface can be specified based on the detection result. However, it is assumed that whether the detected object is an object belonging to the radio wave reflector is identified from the detected surface shape by a known pattern matching process.

  The detection range of the reflecting surface specifying device 2 may be designed as appropriate, but is determined so as to include at least the receivable ranges of the first array antenna 11A and the second array antenna 11B. That is, in the present embodiment, the detection range of the reflecting surface specifying device 2 includes a range from −90 ° to + 90 ° in the horizontal direction, where the front direction of the host vehicle is 0 °.

  Moreover, the reflective surface identification apparatus 2 should just be arrange | positioned in the position designed suitably so that the said detection range may be formed in the own vehicle. For example, the reflecting surface specifying device 2 may be provided near the front end (front bumper or grill) of the host vehicle or the upper end of the windshield.

  Information indicating the relative position of the reflecting surface existing around the host vehicle specified by the reflecting surface specifying device 2 is provided to the in-vehicle communication device 1 as reflecting surface information. The relative position of the reflecting surface with respect to the host vehicle is expressed by, for example, a coordinate on the XY coordinate system with the center at the front end of the host vehicle as the origin and the X axis and the Y axis in the horizontal plane, or a function representing the coordinate group. It only has to be done. For example, the Y-axis is parallel to the vehicle front-rear direction and the direction from the rear to the front is the positive direction, and the X-axis is parallel to the vehicle width direction and the direction from the left to the right is the positive direction. The reflecting surface specifying device 2 corresponds to a reflecting surface position specifying unit described in claims.

  The case where the reflection surface specifying device 2 detects the reflection surface and generates the reflection surface information may be a case where the in-vehicle communication device 1 receives a signal from the mobile terminal 200, for example. As another aspect, the reflecting surface specifying device 2 may generate reflecting surface information and provide it to the in-vehicle communication device 1 when the host vehicle is parked. In that case, the in-vehicle communication device 1 may store the acquired reflection surface information in the storage unit 14 and read the reflection surface information from the storage unit 14 when a signal from the mobile terminal 200 is received.

<About the operation of the position estimation unit 16>
Based on the reflection surface information, the position estimation unit 16 determines whether the arrival direction indicated by the first arrival direction information is an arrival direction detected from a direct wave or an arrival detected from a reflected wave. Identify the direction. More specifically, referring to the reflection surface information, if a reflection surface exists in the direction of the arrival direction to be identified, the arrival direction is detected from the reflected wave. It is determined that If there is no reflecting surface in the direction of the arrival direction, it is determined that the arrival direction is an arrival direction detected from a direct wave.

  The arrival direction detected from the direct wave corresponds to the direction in which the mobile terminal 200 exists (that is, the terminal direction). For convenience, the arrival direction detected from the direct wave is referred to as a direct arrival direction, and the arrival direction detected from the reflected wave is referred to as a reflection arrival direction. When there are a plurality of arrival directions indicated in the reflection surface information, the above identification is performed for each.

  Also, the position estimation unit 16 identifies whether the arrival direction is the direct arrival direction or the reflection arrival direction based on the reflection surface information for the arrival direction indicated by the second arrival direction information.

  FIG. 3 is a conceptual diagram for explaining the operation of the position estimation unit 16 and represents a propagation environment until the radio wave transmitted from the mobile terminal 200 is received by the array antenna 11. A one-dot chain line in the figure represents the position of the reflective surface 301 indicated by the reflective surface information. For convenience, the position of the mobile terminal 200 that is a radio wave transmission source is indicated by a circle.

  In the situation shown in FIG. 3, each array antenna 11 receives a radio wave (that is, a reflected wave) that has been reflected by the reflecting surface 301 and a radio wave that has arrived directly (a direct wave). A solid line arrow indicates a path through which a signal transmitted from the mobile terminal 200 directly reaches the array antenna 11, and a broken line arrow indicates that the signal transmitted from the mobile terminal 200 is reflected by the reflecting surface 301 and is transmitted to the array antenna 11. Represents a route to reach.

  As an example, the arrival direction of the reflected wave at the first array antenna 11A is θ11, and the arrival direction of the direct wave is θ12. Further, the arrival direction of the reflected wave at the second array antenna 11B is θ21, and the arrival direction of the direct wave is θ22.

  As a result, the position estimation unit 16 acquires two arrival directions of θ11 derived from the direct wave and θ11 derived from the reflected wave as the first arrival direction information. Also, as the second arrival direction information, two arrival directions of θ21 derived from the direct wave and θ22 derived from the reflected wave are acquired.

  When the first arrival direction information is acquired, the position estimation unit 16 refers to the reflection surface information and determines whether or not there is a reflection surface in the direction of the arrival direction θ11 when viewed from the first array antenna 11A. In FIG. 3, since there is no reflecting surface in the direction of the arrival direction θ11, it is determined that the arrival direction θ11 is the direct arrival direction. Further, the position estimation unit 16 determines whether or not a reflection surface exists in the direction of the arrival direction θ12 as viewed from the first array antenna 11A. Since the reflection surface 301 exists in the direction of the arrival direction θ12, the arrival direction θ12 is determined to be the reflection arrival direction.

  The position estimation unit 16 represents the positions of the first array antenna 11A and the second array antenna 11B as points in the XY coordinate system based on the installation position data stored in the storage unit 14, and each array The positional relationship between the antenna 11 and the reflecting surface may be recognized in the XY coordinate system. Then, it is only necessary to determine whether or not the reflecting surface 301 exists in the azimuth of the arrival direction θ11 and the azimuth of the arrival direction θ12 viewed from the first array antenna 11A in the XY coordinate system.

  Similarly, the position estimation unit 16 refers to the reflection surface information for each of the arrival directions θ21 and θ22 indicated in the second arrival direction information, and directly determines the arrival direction θ11 as the arrival direction θ12. It is determined that the direction of reflection arrival.

  Then, the position estimation unit 16 calculates the direct arrival direction θ11 indicated in the first arrival direction information, the direct arrival direction θ21 indicated in the second arrival direction information, and the installation position of each array antenna 11 according to the principle of triangulation. The relative position of the mobile terminal 200 is specified.

  In the present embodiment, the relative position of the mobile terminal 200 is estimated based on the direct arrival directions θ11 and θ21 derived from each array antenna 11 as an example, but the present invention is not limited thereto. As in Modification 1 described later, the reflection arrival direction may be used to specify the relative position of the mobile terminal 200.

<Effect of this embodiment>
Here, the problems in the prior art will be described with reference to FIGS. 4 and 5, and then the effects of this embodiment will be described. FIG. 4 is a conceptual diagram illustrating an example of a propagation path until a radio wave transmitted from the mobile terminal 200 is received by the array antenna 11. 4 represents a metal body (that is, a radio wave reflector) such as a body of another vehicle, and 400 represents an object (such as a radio wave attenuator) that attenuates radio waves such as a human body. Although the radio wave attenuator transmits radio waves, its signal strength is reduced. The radio wave reflector 300 is present in a position and shape that reflects the radio wave transmitted from the mobile terminal 200 in the direction in which the array antenna 11 exists, and the radio wave attenuator 400 includes the mobile terminal 200 and the array antenna. 11 exists on a straight line connecting 11.

  In such a situation, the array antenna 11 receives each of the radio wave that has been reflected by the radio wave reflector 300 (that is, the reflected wave) and the radio wave that has passed through the radio wave attenuator 400 (transmitted wave). As an example, it is assumed that the reflected wave from the radio wave reflector 300 comes from the direction of 45 ° for the array antenna 11 and the transmitted wave comes from the direction of 0 °. Note that the transmitted wave belongs to the direct wave from the viewpoint that the arrival direction coincides with the direction in which the mobile terminal 200 exists.

  FIG. 5 is a graph showing the relationship between the search azimuth angle and the combined received power, which is obtained by the arrival direction estimation unit 13 in the situation shown in FIG. When the reflected wave from the radio wave reflector 300 is received by the array antenna 11 while maintaining a sufficient intensity, the arrival direction is detected in the 45 ° direction because the array antenna 11 comes from the 45 ° direction.

  The radio wave reflected a plurality of times is sufficiently attenuated to be equal to or less than the threshold value Th and can be ignored. In other words, the reflected wave here may be a radio wave that arrives after being reflected from the mobile terminal 200 and reflected only once.

  Further, when the transmitted wave is received by the array antenna 11 while maintaining a sufficient intensity, the transmitted wave arrives from the 0 ° direction for the array antenna 11, and therefore the arrival direction is detected in the 0 ° direction.

  In general, when the radio wave transmitted from the mobile terminal 200 is directly received by the array antenna 11 without being reflected by the reflector, the combined received power of the incoming radio wave is higher than the combined received power of the reflected wave. There is a strong tendency to grow. However, even if it is a direct wave, when it is a transmitted wave or when it receives interference of a reflected wave, the combined received power may be smaller than the combined received power of the reflected wave. FIG. 5 shows, as an example, a case where the direct wave is a transmitted wave and the combined received power is smaller than the combined received power of the reflected wave.

  That is, as shown in FIG. 5, the direction in which the combined received power is the largest is not always the direct arrival direction. Therefore, when a plurality of arrival directions are detected, it can be said that it is difficult to identify whether or not the plurality of arrival directions directly indicate the arrival directions based on the magnitude relationship of the combined received power. If the reflected arrival direction is erroneously determined as the direct arrival direction, the position of the mobile terminal 200 is estimated to be different from the actual position.

  For this reason, in the conventional technology, when the host vehicle exists in an environment (so-called multipath environment) in which a signal transmitted from the mobile terminal 200 is reflected and is likely to reach the array antenna 11, There existed a subject that position estimation accuracy fell.

  On the other hand, according to the configuration of the present embodiment, the position estimation unit 16 identifies whether the arrival direction is the direct arrival direction or the reflection arrival direction based on the reflection surface information. Therefore, it is possible to reduce the possibility of erroneously recognizing the reflected arrival direction as a direct arrival direction corresponding to the terminal direction, and accordingly, even if the host vehicle is in a multipath environment, the position of the mobile terminal 200 is more accurately detected. Can be estimated.

  In addition, even when there are a plurality of reflection surfaces and a plurality of reflection waves are received, combinations of the reflection waves and points on the reflection surface (reflection points) can be associated one-to-one. Therefore, the position estimation accuracy does not deteriorate due to the presence of a plurality of reflecting surfaces (in other words, radio wave reflectors). Further, if the concept of Modification 1 or Modification 2 described below is introduced in the present embodiment, the fact that there are a plurality of reflection surfaces increases the information for estimating the position of the mobile terminal 200. As a result, the position can be estimated with higher accuracy.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following modifications are also contained in the technical scope of this invention, Furthermore, the summary other than the following is also included. Various modifications can be made without departing from the scope.

[Modification 1]
In the above, the aspect which estimated the relative position of the portable terminal 200 based on the direct arrival direction in each of the two array antennas 11 was illustrated. That is, in the estimation of the relative position of the mobile terminal 200, an example in which the reflection arrival direction is not used is illustrated, but the present invention is not limited thereto. In the first modification, in order to specify the relative position of the mobile terminal 200, an example in which the reflection arrival direction is used is illustrated.

  As shown in FIG. 6 as a functional block, the position estimation unit 16 in the first modification includes a reflection point specifying unit 161 and an indirect terminal direction specifying unit 162.

  The reflection point specifying unit 161 specifies a position where the radio wave transmitted from the mobile terminal 200 is reflected by the array antenna 11 from the reflection arrival direction and the reflection surface information. The position of the reflection point may be expressed as coordinates in the XY coordinate system, for example. Further, the indirect terminal direction specifying unit 162 specifies the direction in which the mobile terminal 200 is present (referred to as the indirect terminal direction) from the reflection point, based on the angle of the reflection surface at the reflection point and the reflection arrival direction.

  The operations of the reflection point specifying unit 161 and the indirect terminal direction specifying unit 162 will be described more specifically with reference to FIG. FIG. 7 is a conceptual diagram showing a propagation environment until a radio wave transmitted from the mobile terminal 200 is received by the array antenna 11 as in FIG. A one-dot chain line in the figure represents the position of the reflective surface 301 indicated by the reflective surface information. Also, the solid line arrow indicates the path until the radio wave transmitted from the portable terminal 200 reaches the first array antenna 11A directly, and the broken line arrow indicates the first wave directly reflected on the reflecting surface 301 by the radio wave transmitted from the portable terminal 200. Each route to reach the array antenna 11A is shown. The angle θ11 represents the direct arrival direction at the first array antenna 11A, and the angle θ12 represents the reflection arrival direction at the first array antenna 11A. Further, the angle θ3 represents an angle with respect to the 0 ° direction (here, the Y axis) of the first array antenna 11A at the reflection point 302 on the reflection surface 301.

  For convenience, portions related to the second array antenna 11B are omitted, and portions related to the arrival direction of radio waves received by the first array antenna 11A will be described. Of course, the concept described below can also be applied to the second array antenna 11B.

  In the situation shown in FIG. 7, the reflection point specifying unit 161 reflects the reflection point from the position of the first array antenna 11A in the XY coordinate system, the reflection arrival direction θ12, and the coordinate group (or function) constituting the reflection surface 301. The position of 302 is specified.

  Next, the indirect terminal direction specifying unit 162 calculates an angle θ3 between the tangent to the reflecting surface 301 at the reflection point 302 specified by the reflection point specifying unit 161 and the Y axis. And direction (namely, indirect terminal direction) (theta) 4 in which the portable terminal 200 exists seen from the reflective point 302 is specified from angle (theta) 3 and reflection arrival direction (theta) 12. The indirect terminal direction θ4 is a value obtained by adding a value obtained by doubling the angle θ3 to the reflection arrival direction θ12. That is, θ4 = θ12 + 2 * θ3.

  As described above, the position of the reflection point 302, the indirect terminal direction θ4, the position of the first array antenna 11A, and the direct arrival direction θ11 in the first array antenna 11A are all known. Therefore, by applying the principle of triangulation with the line segment connecting the reflection point 302 and the installation position of the first array antenna 11A as a base line, the relative position of the mobile terminal 200 can be determined from the indirect terminal direction θ4 and the direct arrival direction θ11. Can be estimated. That is, the position estimation unit 16 uses the reflection arrival direction in the first array antenna 11A, so that the relative position of the mobile terminal 200 can be obtained without using the direct arrival direction (and reflection arrival direction) in the second array antenna 11B. Can be specified.

  In the prior art and the above-described embodiments, two array antennas 11 are required to specify the relative position of the mobile terminal 200 using the principle of triangulation. On the other hand, according to the configuration of the first modification, the position of the mobile terminal 200 can be estimated by one array antenna 11.

  Therefore, according to the configuration of the first modification, even if the in-vehicle communication device 1 has only one array antenna 11 (see FIG. 8), the array antenna 11 receives the direct wave and the reflected wave. If it can, the position of the mobile terminal 200 can be estimated. Further, according to the configuration of the first modification, although a plurality of array antennas 11 are provided, even when only one array antenna 11 can receive radio waves from the portable terminal 200, the array antenna 11 Can receive the direct wave and the reflected wave, the position of the mobile terminal 200 can be estimated.

  Furthermore, according to the configuration of the first modification, as shown in FIG. 9, even when the direct wave from the mobile terminal 200 cannot be received, the reflected wave from a plurality of directions can be received. The relative position of the mobile terminal 200 can be estimated. Specifically, the reflection point specifying unit 161 specifies a reflection point corresponding to each of a plurality of reflection arrival directions, and the indirect terminal direction specifying unit 162 specifies an indirect terminal direction corresponding to each reflection point. And the position of the portable terminal 200 is specified by the principle of triangulation from the combination of a plurality of reflection points and the indirect terminal direction.

  In addition, the case where the direct wave from the portable terminal 200 cannot be received means that the radio wave reflector 300 or the like exists on a straight line connecting the portable terminal 200 and the array antenna 11, or the signal intensity of the direct wave is sufficiently attenuated. This is the case, for example, when the radio wave attenuator 400 is present. In FIG. 9, 301A and 301B represent reflection surfaces indicated in the reflection surface information, and θ12 and θ13 represent reflection arrival directions.

[Modification 2]
In the first modification, the relative position of the mobile terminal 200 is estimated from the direct arrival direction in the first array antenna 11A and the indirect arrival direction for the reflection point 302 determined from the reflection arrival direction in the first array antenna 11A. Although illustrated, it is not restricted to this.

  The relative position of the mobile terminal 200 may be estimated from the direct arrival direction at the first array antenna 11A and the indirect arrival direction for the reflection point determined from the reflection arrival direction at the second array antenna 11B. Conversely, the relative position of the mobile terminal 200 may be estimated from the direct arrival direction at the second array antenna 11B and the indirect arrival direction for the reflection point determined from the reflection arrival direction at the first array antenna 11A. .

  Further, based on the indirect arrival direction for the reflection point determined from the reflection arrival direction in the first array antenna 11A and the indirect arrival direction for the reflection point determined from the reflection arrival direction in the second array antenna 11B, The position may be estimated.

  Further, the position of the mobile terminal 200 determined from the direct arrival direction at the first array antenna 11A and the direct arrival direction at the second array antenna 11B is corrected based on the direction in which the mobile terminal 200 exists from an arbitrary reflection point. Also good.

1000 position estimation system, 100 in-vehicle system, 1 in-vehicle communication device (position estimation device), 11 array antenna, 11A first array antenna, 11B second array antenna, 12 receiving unit, 12A first receiving unit, 12B second receiving unit , 13 arrival direction estimation unit, 13A first arrival direction estimation unit, 13B second arrival direction estimation unit, 14 storage unit, 15 reflecting surface information acquisition unit, 16 position estimation unit, 131A complex weight assignment unit, 132A weighting command unit, 133A Correlation calculation unit, 134A Arrival direction acquisition unit, 161 Reflection point specification unit, 162 Indirect terminal direction specification unit, 2 Reflection surface specification device (reflection surface position specification unit), 200 Mobile terminal

Claims (6)

Mounted on the vehicle,
An array antenna (11, 11A, 11B) comprising a plurality of antenna elements for receiving radio waves from a mobile terminal carried by a user of the vehicle;
An arrival direction estimation unit (13, 13A, 13B) for estimating an arrival direction of radio waves received by the array antenna;
A position estimation unit (16) for estimating a position of the mobile terminal with respect to the vehicle based on an estimation result of the arrival direction estimation unit;
An object existing in a predetermined range around the vehicle is detected, and a position and an angle of the reflection surface, which is a surface that can reflect radio waves from the mobile terminal, are identified based on the position of the detected object. And a reflecting surface position specifying part (2),
The position estimation unit
It is determined whether the reflection surface specified by the reflection surface position specification unit exists in the arrival direction estimated by the arrival direction estimation unit, and the arrival direction is a direction in which the reflection surface does not exist When there is a direct arrival direction, the position estimation device estimates the position of the mobile terminal with respect to the vehicle based on the direct arrival direction. In claim 1,
In the case where the reflection surface is present in the arrival direction estimated by the arrival direction estimation unit, the position estimation unit indicates the arrival direction of the radio wave transmitted from the mobile terminal and is received Is recognized as the reflection arrival direction,
A reflection point identification unit (161) that identifies a reflection point that is a position reflected from the reflection arrival direction and the position of the reflection surface until the radio wave transmitted from the mobile terminal is received by the array antenna. )When,
Based on the angle of the reflection surface at the reflection point specified by the reflection point specifying unit and the reflection arrival direction, the indirect terminal that specifies the indirect terminal direction that is the direction in which the mobile terminal exists as seen from the reflection point A direction specifying part (162),
The position estimating unit can estimate the position of the mobile terminal based on the position of the reflection point specified by the reflection point specifying unit and the indirect terminal direction specified by the indirect terminal direction specifying unit. Position estimation device. In claim 2,
The position estimating unit is based on the installation position of the array antenna in the vehicle, the direct arrival direction of the array antenna, the position of the reflection point, and the indirect terminal direction specified by the indirect terminal direction specifying unit. And estimating the position of the portable terminal. In claim 2 or 3,
The array antenna includes a first array antenna and a second array antenna provided at different positions,
The arrival direction estimation unit estimates an arrival direction of radio waves received at each of the first array antenna and the second array antenna,
The position estimation unit
When the direct arrival direction in the first array antenna and the direct arrival direction in the second array antenna can be acquired, the mobile terminal for the vehicle based on the direct arrival direction in each of the array antennas A position estimation device characterized by estimating the position of the. In claim 4,
The direct arrival direction in any one of the first array antenna and the second array antenna cannot be obtained, and the reflection arrival direction in at least one of the first array antenna and the second array antenna If you can get
The reflection point specifying unit specifies the reflection point from the reflection arrival direction that has been acquired,
The indirect terminal direction specifying unit specifies the indirect terminal direction based on the angle of the reflection surface at the reflection point specified by the reflection point specifying unit and the reflection arrival direction,
The position estimation unit includes an installation position of the array antenna from which the direct arrival direction can be obtained, the direct arrival direction from which the direct arrival direction is obtained, a position of the reflection point, and the indirect to the reflection point. A position estimation device that estimates the position of the mobile terminal based on a terminal direction. In any one of Claim 2 to 4,
When a plurality of reflection arrival directions can be acquired,
The reflection point specifying unit specifies the reflection point corresponding to each of the reflection arrival directions,
The indirect terminal direction specifying unit specifies the indirect terminal direction corresponding to each of the reflection points specified by the reflection point specifying unit,
The said position estimation part estimates the position of the said portable terminal based on the position of the said several reflective point, and the said indirect terminal direction corresponding to each said reflective point, The position estimation apparatus characterized by the above-mentioned.

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