JP2020034444A - Portable machine position estimation system - Google Patents

Abstract

To provide a portable machine position estimation system that can improve a position estimation accuracy of a portable machine that communicates with an on-vehicle device.SOLUTION: The on-vehicle device is configured so as to include a matching ECU 110, a vehicle-side transmission part 180, four vehicle-side LF antennas 181F to 181L, a vehicle-side receiving part 190, an on-vehicle RF antenna 195, and an input part 140, an electronic key 200 is configured so as to include a key-side receiving part 210, a key-side LF antenna 221, a key-side transmission part 220, a key-side RF antenna 215, and a key-side control part 230, the key-side receiving part 210 is configured so as to include an RSSI detection circuit 211 and a vector detection circuit 212, the RSSI detection circuit 211 detects the RSSI of a vehicle signal received by the key-side RF antenna 215, the vector detection circuit 212 detects a vector direction, which is a direction of a magnetic field vector of the vehicle signal received by the key-side RF antenna 215.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a portable device position estimating system, and more particularly, to improving the position estimation accuracy of a portable device.

  A technique for estimating the position of a portable device is known. In Patent Literature 1, the distance between the on-vehicle device and the portable device is estimated from the received signal strength of radio waves received by the portable device from three or more on-vehicle devices. Then, the position of the portable device is estimated from the three or more distances.

JP 2017-44563 A

  According to the technique described in Patent Document 1, for example, in a vehicle trunk, there is a possibility that the attenuation of the received signal strength is increased due to the influence of the seat and the floor. Then, position estimation using the received signal strength may not be performed well, and there may be an erroneous determination that the portable device is outside the vehicle compartment despite the presence of the portable device in the trunk.

  Accordingly, the present disclosure has been made in view of the above-described problems, and has as its object to provide a portable device position estimation system that can improve the position estimation accuracy of a portable device in a portable device that communicates with an in-vehicle device. And

  The present disclosure employs the following technical means to achieve the above-described object.

The present disclosure relates to a portable device position estimation system (10) for performing wireless communication between an in-vehicle device (100) mounted on a vehicle and a portable device (200) carried by a user, and estimating a position where the portable device exists. hand,
The in-vehicle device causes at least three transmission antennas (181) for transmitting radio waves, a reception antenna (195) for receiving radio waves, and transmits radio waves from the transmission antennas, and processes the radio waves received by the reception antennas. A control unit (110);
The portable device includes a sub receiving antenna (215) for receiving a radio wave from the transmitting antenna, a received signal strength of the radio wave from each transmitting antenna received by the sub receiving antenna, and a radio wave from each transmitting antenna. Detectors (211, 212) for detecting the direction of the magnetic field vector, a sub-transmission antenna (221) for transmitting a radio wave to a reception antenna, and a radio wave transmitted from the sub-transmission antenna, which is received by the sub-reception antenna A sub-control unit (230) for processing radio waves,
One of the control unit and the sub-control unit uses the magnitude of the received signal strength of radio waves from three or more transmission antennas detected by the detection unit to estimate the position where the portable device is located (124). ) And when the position estimated by the position estimating unit is within the difficult range (22) where it is difficult to estimate the position only by the magnitude of the received signal strength, the magnetic field vector of the radio wave from two or more transmitting antennas And a correction determining unit (123) that determines whether or not to correct the position estimated by the position estimating unit by comparing the degree of coincidence of the direction with the threshold. The portable device position estimating system includes a position correcting unit that corrects the position estimated by the position estimating unit to a specific range where the direction of the magnetic field vector has a high degree of coincidence.

  According to the present disclosure, first, the position where the portable device is present is estimated using the received signal strength. Since there is a correlation between the received signal strength and the distance between the transmitting antenna and the portable device, the position estimating unit uses the magnitude of the received signal strength of radio waves from three or more transmitting antennas to use the portable device. Estimate the position. As described above, the position where the portable device exists can be estimated using the received signal strength, but there is a specific range where the estimation accuracy is low due to environmental factors.

  Such a specific range is determined by the position of a conductor, for example, a metal body included in the vehicle. Therefore, when the position is within the difficult range where it is difficult to estimate the position only by the magnitude of the received signal strength, the correction determination unit By comparing the degree of coincidence of the direction of the magnetic field vector of the radio wave from the transmitting antenna with a threshold value, it is determined whether or not the position estimated by the position estimating unit should be corrected.

  Since the specific range is surrounded by the conductor, the directions of the magnetic field vectors are easily aligned, and the degree of coincidence of the direction of the magnetic field vector from the specific antenna is high. Therefore, when the position estimated using the received signal strength is within the difficult range, whether or not the position is within the difficult range can be estimated using the degree of coincidence of the direction of the magnetic field vector.

  Then, the correction determining unit determines whether or not the position estimated using the degree of coincidence should be corrected. If it is determined that the position should be corrected, the position correcting unit estimates that the portable device exists within the specific range. As a result, even when it is estimated that the portable device exists in a difficult range where the estimation accuracy of the received signal strength is low, the correction is performed using the direction of the magnetic field vector to improve the estimation accuracy of the position where the portable device exists. can do.

  Note that the reference numerals in parentheses of the above-described units are examples showing the correspondence with specific units described in the embodiments described later.

It is a figure showing the schematic structure of the electronic key position estimating system of a 1st embodiment. FIG. 3 is a diagram illustrating a position of an LF antenna 181 in a vehicle. FIG. 7 is a diagram showing a key detection area corresponding to each LF antenna 181. It is a figure which shows RSSI distance relationship 135 notionally. It is a figure explaining the magnetic field vector of right LF antenna 181R. It is a figure explaining the magnetic field vector of back side LF antenna 181B. It is a figure explaining the magnetic field vector of left LF antenna 181L. It is a figure explaining the magnetic field vector of front side LF antenna 181F. It is a figure for comparing magnetic field vectors. 9 is a flowchart illustrating a process executed by a key-side control unit. It is a flowchart explaining the onboard equipment side process which the vehicle side control part 120 performs.

  Hereinafter, an embodiment of a portable device position estimation system will be described with reference to the drawings. In the embodiment described below, the portable device is the electronic key 200. That is, the embodiment described below is an electronic key position estimation system 10.

(1st Embodiment)
The first embodiment will be described with reference to FIGS. The electronic key position estimating system 10 according to the first embodiment includes an on-vehicle device 100 and an electronic key 200. The vehicle-mounted device 100 is a vehicle-mounted device mounted on the vehicle 11, and the electronic key 200 is a portable device carried by a user. The in-vehicle device 100 and the electronic key 200 transmit and receive various information by wireless communication. The electronic key position estimating system 10 has a function as a portable device position estimating system for estimating a position where the electronic key 200 is present.

  The electronic key position estimating system 10 has a function of executing collation of the electronic key 200 based on wireless communication between the vehicle-mounted device 100 and the electronic key 200, and executing or permitting a predetermined process when the collation is established. . The collation of the electronic key 200 is to confirm whether the electronic key 200 is a legitimate electronic key 200 associated with the vehicle-mounted device 100 in advance.

  The predetermined process permitted or executed when the verification is successful includes, for example, the following. When the authorized electronic key 200 is located in the cabin of the vehicle 11, the start of the vehicle engine is permitted. In addition, the unlocking of the vehicle door is permitted when the authorized electronic key 200 is located in a predetermined area outside the vehicle. Further, when the authorized electronic key 200 approaches the vehicle 11 by a predetermined distance, a welcome process for turning on a hazard lamp of the vehicle 11 or the like is executed. As described above, the electronic key position estimating system 10 permits or executes different processes according to the position of the electronic key 200 with respect to the vehicle 11.

  The electronic key position estimating system 10 estimates the position of the electronic key 200 with respect to the vehicle 11 when executing or permitting the above-described predetermined processing based on the collation. Hereinafter, the configuration of the electronic key position estimation system 10 for estimating the position of the electronic key 200 with respect to the vehicle 11 will be described.

  First, the configuration of the vehicle-mounted device 100 will be described. As shown in FIG. 1, the vehicle-mounted device 100 includes a verification ECU 110, a vehicle-side transmission unit 180, four vehicle-side LF antennas 181F to 181L, a vehicle-side reception unit 190, a vehicle-mounted RF antenna 195, and an input unit 140. You. The four vehicle-side antennas 181F to 181L are transmission antennas for transmitting radio waves. The four vehicle-side antennas 181F to 181L include a front LF antenna 181F disposed on the front side of the vehicle 11, a right LF antenna 181R disposed on the right side of the vehicle 11, a left LF antenna 181L disposed on the left side of the vehicle 11, and a vehicle. 11 is a rear-side LF antenna 181B disposed rearward of FIG. The rear LF antenna 181B is arranged in a trunk room 12 located behind the vehicle 11. Hereinafter, when the four vehicle-side LF antennas 181F to 181L are not distinguished, they are simply described as LF antenna 181.

  The verification ECU 110 includes a vehicle-side control unit 120 and a storage unit 130, and executes a verification process of the electronic key 200. The verification ECU 110 is connected to the vehicle-side transmission unit 180, the vehicle-side reception unit 190, and the input unit 140, and transmits and receives information to and from each other. Therefore, verification ECU 110 functions as a control unit that transmits radio waves from LF antenna 181 and processes radio waves received by on-vehicle RF antenna 195. ECU is an abbreviation for electronic control unit.

  The verification ECU 110 mainly includes a microcomputer. The verification ECU 110 executes various processes including verification of the electronic key 200 and estimation of the position of the electronic key 200 by executing a program stored in a storage device such as a ROM or a storage unit 130 by a processor such as a CPU. Execute in cooperation with. Note that at least a part of the function of the verification ECU 110 may be provided by a dedicated IC or the like. When performing the verification process, verification ECU 110 controls vehicle-side transmission section 180 to transmit a request signal from LF antenna 181. The verification ECU 110 receives the response signal as a response to the request signal via the in-vehicle RF antenna 195, and verifies the electronic key 200 by verifying the ID included in the response signal.

  The input unit 140 is operated by a user to input various information to the vehicle-mounted device 100. The input unit 140 is, for example, a switch provided in the cabin of the vehicle 11.

  The vehicle-side transmission unit 180 modulates and amplifies the vehicle signal with the LF wave or the VLF wave under the control of the verification ECU 110, and causes the LF antenna 181 to transmit the signal as a radio wave. The radio wave transmitted from the LF antenna 181 is a vehicle-mounted antenna radio wave. LF is an abbreviation for Low Frequency, and VLF is an abbreviation for Very Low Frequency. In this specification, the term LF is used, including VLF. When a request signal is transmitted as a vehicle signal, information that requests the electronic key 200 to return a response signal including a unique ID is included. Each vehicle signal includes identification information that makes it possible to identify which LF antenna 181 the transmission source is.

  FIG. 2 shows the position of the LF antenna 181. The front LF antenna 181F is provided near the center in the vehicle width direction at the front end of the vehicle compartment. The right LF antenna 181R is provided on the inside door knob of the right door of the vehicle. The rear LF antenna 181B is provided near the center in the vehicle width direction in the trunk room 12 located behind the passenger compartment. The left LF antenna 181L is provided on the outside door knob of the left door. Therefore, the right LF antenna 181R and the left LF antenna 181L are arranged at an interval in the vehicle width direction. The position of the LF antenna 181 can be variously changed, and the number of the LF antennas 181 can be variously changed.

  Around these LF antennas 181 are formed detectable areas. The detectable area is an area where the electronic key 200 can receive the vehicle signal transmitted from the LF antenna 181 with a received signal strength (hereinafter, RSSI) equal to or higher than a predetermined threshold. The size of the detectable area can be adjusted to some extent by setting the transmission output of the LF antenna 181, the reception sensitivity of the electronic key 200, and the like. Also, the shape of the detectable area can be adjusted by changing the antenna shape or the like.

  The description returns to FIG. The vehicle-side receiving unit 190 receives a key signal transmitted by an RF (Radio Frequency) wave from the electronic key 200 via the on-vehicle RF antenna 195. The on-vehicle RF antenna 195 is a receiving antenna that receives a radio wave. The in-vehicle RF antenna 195 gives an electric signal based on the received radio wave to the vehicle-side receiving unit 190. The on-vehicle RF antenna 195 is provided at a position appropriately set in the vehicle 11. For example, the on-vehicle RF antenna 195 is provided at a position near the center of the vehicle 11 in the vehicle interior. The vehicle-side receiving section 190 amplifies the electric signal obtained from the on-vehicle RF antenna 195, demodulates a key signal from the electric signal, and outputs the key signal to the verification ECU 110.

  The key signal including the unique ID transmitted from the electronic key 200 as a reply of the request signal is a response signal. The key signal may further include RSSI information indicating the RSSI when the electronic key 200 receives the vehicle signal. The RSSI information includes identification information that enables identification of which LF antenna 181 is the source of the RSSI and the vehicle signal. The key signal may further include vector information indicating a vector direction when the electronic key 200 receives the vehicle signal.

  Next, the configuration of the electronic key 200 will be described. The electronic key 200 includes a key-side receiving unit 210, a key-side LF antenna 221, a key-side transmitting unit 220, a key-side RF antenna 215, and a key-side control unit 230.

  The key-side RF antenna 215 functions as a sub-receiving antenna that receives a radio wave from the LF antenna 181. The key-side RF antenna 215 has a function as a three-axis antenna. The key-side RF antenna 215 includes an X-axis antenna, a Y-axis antenna, and a Z-axis antenna that are orthogonal to each other. Each of the X-axis antenna, the Y-axis antenna, and the Z-axis antenna is configured by, for example, a coil antenna.

  The key receiving section 210 acquires, via the key RF antenna 215, an electric signal indicating the in-vehicle antenna radio wave transmitted from the LF antenna 181. Key-side receiving section 210 demodulates and amplifies the electric signal to extract a vehicle signal, and outputs the signal to key-side control section 230.

  The key receiving section 210 is configured to include an RSSI detection circuit 211 and a vector detection circuit 212. The RSSI detection circuit 211 is a circuit that detects the in-vehicle antenna radio wave received by the key-side RF antenna 215, that is, the RSSI of the vehicle signal. The RSSI detection circuit 211 outputs the detected RSSI to the key-side control unit 230. The RSSI detection circuit 211 corresponds to a detection unit.

  The vector detection circuit 212 is a circuit that detects a vector direction that is a direction of a magnetic field vector of a vehicle-mounted antenna radio wave, that is, a vehicle signal received by the key-side RF antenna 215. The vector detection circuit 212 outputs the detected vector direction to the key-side control unit 230. The vector detection circuit 212 corresponds to a detection unit.

  The vector direction indicates the direction of the magnetic field in the three-dimensional space at the position of the key-side RF antenna 215. The vector detection circuit 212 first detects the magnetic field strength of each of the X-axis, Y-axis, and Z-axis of the key-side RF antenna 215. The magnetic field strength in each of the three axes is detected based on the current flowing through each of the X-axis antenna, the Y-axis antenna, and the Z-axis antenna of the key-side RF antenna 215. Then, the vector detection circuit 212 detects the direction of the magnetic field vector by calculating the ratio of the magnetic field strength on the X axis, the magnetic field strength on the Y axis, and the magnetic field strength on the Z axis. The vector detection circuit 212 calculates the square root of the sum of the square of the X-axis magnetic field strength, the square of the Y-axis magnetic field strength, and the square of the Z-axis magnetic field strength, and determines the magnetic field strength, that is, the magnitude of the magnetic field vector. Can also be detected.

  The key-side transmitting section 220 modulates and amplifies the key signal with an RF wave under the control of the key-side control section 230 and causes the key-side LF antenna 221 to transmit the key signal. The key-side LF antenna 221 functions as a sub-transmission antenna that transmits a radio wave to the vehicle-mounted RF antenna 195. The key signal is generated by the key-side control unit 230. The key signal includes RSSI information indicating the RSSI of the vehicle signal, vector information indicating the vector direction, and the unique ID of the electronic key 200. Since the response signal described above is also a key signal, the response signal also includes a unique ID.

  The key-side control unit 230 is mainly configured by a microcomputer. The key-side control unit 230 executes various processes including collation of the electronic key 200 and positioning of the electronic key 200, which will be described later, by executing a program stored in a storage device such as a ROM by a processor such as a CPU. It has a function to execute in cooperation with the H.100. At least a part of the function of the key-side control unit 230 may be provided by a dedicated IC or the like. Therefore, the key-side control unit 230 is a sub-control unit, controls the key-side transmission unit 220 to transmit radio waves from the key-side RF antenna 215, and controls the key-side reception unit 210 to control the key-side LF antenna 221. Process the information of the received radio wave.

  Upon receiving the request signal, the key-side control section 230 transmits a response signal including an ID unique to itself. Specifically, when the key-side control unit 230 acquires the vehicle signal via the key-side receiving unit 210, the key-side control unit 230 determines which LF antenna 181 has transmitted the vehicle signal based on the identification information included in the vehicle signal. It has a function to specify.

  Further, the key-side controller 230 has a function of determining whether or not the key-side receiver 210 has received a vehicle signal from three or more LF antennas 181 within a predetermined time. The predetermined time can be determined in advance from the transmission time required when all the LF antennas 181 sequentially transmit the vehicle signal.

  Further, the key-side control unit 230 generates a key signal using the RSSI and the vector direction of the vehicle signal transmitted from each LF antenna 181 and received by the key-side receiving unit 210, and generates the key signal using the key-side LF antenna 221 is transmitted.

  Next, the function of the verification ECU 110 for estimating the position of the electronic key 200 with respect to the vehicle 11 will be described. As shown in FIG. 1, the verification ECU 110 includes a vehicle-side control unit 120 and a storage unit 130. The vehicle-side control unit 120 includes, as functional blocks, an RSSI acquisition unit 121, a vector acquisition unit 122, a correction determination unit 123, a key area estimation unit 124, and a position correction unit 125.

  When the key signal received by the vehicle-side receiving unit 190 includes the RSSI information, the RSSI obtaining unit 121 obtains the RSSI when the electronic key 200 receives the vehicle signal from the RSSI information. Hereinafter, the RSSI when the electronic key 200 receives the vehicle signal transmitted from the front LF antenna 181F is referred to as the front RSSI, and the RSSI when the electronic key 200 receives the vehicle signal transmitted from the right LF antenna 181R is the right. RSSI. Further, the RSSI when the electronic key 200 receives the vehicle signal transmitted from the rear LF antenna 181B is defined as the rear RSSI, and the RSSI when the electronic key 200 receives the vehicle signal transmitted from the left LF antenna 181L. Let it be the left RSSI.

  When the key signal received by the vehicle-side receiving unit 190 includes vector information, the vector obtaining unit 122 obtains a vector direction when the electronic key 200 receives the vehicle signal from the vector information. Hereinafter, the vector direction when the electronic key 200 receives the vehicle signal transmitted from the front LF antenna 181F will be referred to as a front vector direction, and similarly, the vector direction corresponding to the right LF antenna 181R will be referred to as a right vector direction. The vector direction corresponding to the LF antenna 181B is defined as a rear vector direction, and the vector direction corresponding to the left LF antenna 181L is defined as a left vector direction.

  The key area estimating unit 124 is a position estimating unit, and estimates a position where the electronic key 200 exists. The key area estimating unit 124 estimates the position where the electronic key 200 is located, using the magnitude of the RSSI of the radio wave from the LF antenna 181. The key area estimating unit 124 determines an area where the presence of the electronic key 200 is detected for each LF antenna 181 based on the RSSI acquired by the RSSI acquiring unit 121. This area is hereinafter referred to as a key detection area.

  FIG. 3 shows a key detection area corresponding to each LF antenna 181. In FIG. 3, the key detection area corresponding to each LF antenna 181 is denoted by “a” added to the symbol of each LF antenna 181.

  Each key detection area is determined from the RSSI when the electronic key 200 receives the vehicle signal transmitted from each LF antenna 181 and the RSSI distance relationship 135 shown in FIG. FIG. 4 is a diagram conceptually showing the RSSI distance relationship 135. As shown in FIG. 4, the horizontal axis in the RSSI distance relationship 135 is distance. This distance is the distance from the LF antenna 181 to the electronic key 200. The vertical axis is the RSSI detected when the electronic key 200 receives the vehicle signal transmitted from the LF antenna 181.

  As shown in FIG. 4, it is known that RSSI decreases as the communication distance increases. The RSSI distance relationship 135 is a relationship between the RSSI and the communication distance. The RSSI distance relationship 135 is a relationship determined based on an experiment, and is stored in the storage unit 130 or the like.

  In FIG. 3, each key detection area is circular. The key detection area means that the electronic key 200 exists on the circumference of this circle. Note that the key detection area does not necessarily have to be circular, and may have a shape other than a circle, such as an ellipse. When the key detection area has a shape other than a circle, for example, the distance obtained by applying the RSSI distance relationship 135 to the detected RSSI is multiplied by a coefficient for each direction determined based on the directivity of the LF antenna 181. A key detection area may be created.

  Each key detection area shown in FIG. 3 shows an ideal state, and all key detection areas intersect at a position where the electronic key 200 exists. To achieve such an ideal state, the RSSI detected by the RSSI detection circuit 211 needs to be a true value. However, the RSSI fluctuates due to various errors even if the distance between the LF antenna 181 and the electronic key 200 is the same.

  If the detected RSSI includes an error, the plurality of key detection areas do not intersect at one point. Therefore, the key area estimating unit 124 estimates the position where the electronic key 200 is present from the intersection of each key detection area in consideration of the influence of the error. Such an estimated existence position may indicate a certain point, or may be a range having a certain extent.

  As shown in FIG. 2, there is a specific range 21 in which it is difficult to estimate the location of the electronic key 200 in the vehicle interior. The specific range 21 is a region surrounded by a metal vehicle frame, such as the trunk room 12, for example. In the trunk room 12, the seat skeleton of a rear seat located at the rear of the vehicle is made of metal, and the left and right sides of the trunk room 12 are surrounded by metal frames. In the specific range 21 surrounded by such a metal member, since the attenuation of the RSSI is increased by the metal member, the accuracy of the distance obtained by applying the RSSI distance relationship 135 to the RSSI detected by the electronic key 200 is reduced. . Then, although actually located in the specific range 21, as shown in FIG. 2, it may be estimated that it exists in the difficult range 22 located far behind the specific range 21. In other words, the difficult range 22 is a range in which it is difficult to determine that the electronic key 200 actually exists in the difficult range 22 using only RSSI, and the electronic key 200 may actually exist in the specific range 21. There is. Such a specific range 21 is a known area such as the trunk room 12 because it is generated by a structure in the vehicle. Therefore, when the existence position estimated by the RSSI distance relationship 135 is within the difficult range 22, it is necessary to verify whether the estimation that the position is within the difficult range 22 is correct by an estimation method different from RSSI. Therefore, in the present embodiment, the correction determination unit 123 verifies the estimated position using the vector information, and determines whether or not the correction should be performed. Then, the position correcting unit 125 corrects the existing position when the correction determining unit 123 determines that correction is necessary.

  Next, a method of verifying an estimated position using vector information will be described with reference to FIGS. 5 to 8 show the trunk room 12 and the vector direction when the electronic key 200 receives the vehicle signal transmitted from each LF antenna 181 in the rear of the trunk room 12. 5 to 8, not only the direction of the magnetic field vector is indicated by an arrow but also the magnitude of the magnetic field vector is indicated by the length of the arrow. The large arrow shown in FIGS. 5 to 8 indicates a rough vector direction. In each figure, the range surrounded by the two-dot chain line located on the lower side corresponds to the specific range 21, and the range surrounded by the broken line located on the upper side corresponds to the difficult range 22. 5 to 8, it can be seen that the degree of coincidence in the vector directions of the four figures in the difficult range 22 is lower than the degree of coincidence in the specific range 21. In other words, the vector directions in the specific range 21 are similar to each other. In the vicinity of the metal, the vector direction of the magnetic field changes in the direction along the metal. Therefore, the vector directions change more similar to each other in the specific range 21 than in the difficult range 22.

  This becomes more apparent when FIG. 9 is a simplified illustration of the magnetic field vectors shown in FIGS. As shown in FIG. 9, the vector directions in the specific range 21 are similar to each other. On the other hand, in the difficult range 22 outside the specific range 21, the degree of coincidence in the vector direction is low and they are not similar. By using such a degree of coincidence in the vector direction, it can be determined whether or not it is within the specific range 21. The specific range 21 is a range in which the RSSI has a lower correlation with the distance due to the influence of the metal present in the surrounding area. Therefore, in the position estimation based on the RSSI, the position of the electronic key 200 may be erroneously estimated. However, with respect to the direction of the magnetic field vector, it can be said that the specific range 21 is a range that can be distinguished from the difficult range 22 due to the influence of the surrounding metal.

  Next, a key-side process executed by the key-side control unit 230 of the electronic key 200 to estimate the position of the electronic key 200 with respect to the vehicle 11 in cooperation with the verification ECU 110 will be described with reference to FIG. The key-side processing is periodically executed at a predetermined cycle.

  In step S11, it is determined whether or not the key-side receiving section 210 has received the vehicle signals sequentially transmitted from the LF antennas 181 at predetermined time intervals. If an affirmative determination is made in step S11, the process proceeds to step S12. If a negative determination is made in step S11, the current key-side processing ends.

  In step S12, the RSSI detected by the RSSI detection circuit 211 when the vehicle signal from each LF antenna 181 is received is acquired, and the process proceeds to step S13.

  In step S13, the vector direction detected by the vector detection circuit 212 when the vehicle signal is received from each LF antenna 181 is obtained, and the process proceeds to step S14.

  In step S14, the key-side transmitting section 220 is controlled to transmit a key signal from the key-side LF antenna 221 to end the key-side processing. The key signal includes identification information of each LF antenna 181, RSSI information of each LF antenna 181, vector information, and the like.

  Next, an in-vehicle device-side process executed by the vehicle-side control unit 120 of the verification ECU 110 to estimate the position of the electronic key 200 with respect to the vehicle 11 in cooperation with the electronic key 200 will be described with reference to FIG. The in-vehicle device-side processing is periodically executed at a predetermined cycle. Alternatively, the in-vehicle device-side processing may be started when the start condition is satisfied at any time such as when a push switch for starting the vehicle engine provided in the vehicle compartment is pressed.

  In step S21, vehicle signals are sequentially transmitted from all the LF antennas 181 at predetermined time intervals, and the process proceeds to step S22. Each vehicle signal or one of the vehicle signals includes information requesting the electronic key 200 to return a key signal including RSSI information and vector information.

  In step S22, it is determined whether or not a key signal including RRSI information and vector information when the electronic key 200 receives each of the vehicle signals transmitted in step S21 is received via the in-vehicle RF antenna 195, and is received. In this case, the process proceeds to step S23, and if not received, the current on-vehicle device-side processing ends.

  In step S23, the front RSSI, the right RSSI, the rear RSSI, and the left RSSI are obtained from the RSSI information included in the received key signal, and the process proceeds to step S24. The process in step S23 is a process executed by the RSSI acquisition unit 121.

  In step S24, the RSSI is applied to the RSSI distance relationship 135 illustrated in FIG. 4 to calculate a distance, and the process proceeds to step S25. In step S24, a key detection area is determined for each LF antenna 181 based on the calculated distance.

  In step S25, the location of the electronic key 200 is calculated based on the calculated key detection area, and the process proceeds to step S26. Theoretically, three or more key detection areas intersect at one point, and that point is the position where the electronic key 200 exists. However, RSSI includes errors due to various factors. Therefore, the four key detection areas corresponding to the four LF antennas 181 do not intersect at one point, and in most cases, an overlapping area in which the four key detection areas overlap is obtained. Further, depending on the radio wave environment, there is a possibility that the four key detection areas do not overlap and only the three key detection areas overlap. In step S25, a point in the area where the largest number of detection areas overlap, for example, the center of gravity of that area, is calculated as the location of the electronic key 200.

  In step S26, it is determined whether or not the calculated existence position is within the difficult range 22, and if it is within the difficult range 22, the process proceeds to step S27. If not, the process proceeds to step S211. If it is not within the difficult range 22, it is determined that no correction is required, and the existence position calculated in step S25 is determined.

  In step S27, since it is within the difficult range 22, the verification is necessary. Therefore, the front vector direction, the right vector direction, the rear vector direction, and the left vector direction are obtained from the vector information included in the received key signal. Move to S28. The process of step S27 is a process executed by the vector acquisition unit 122.

  In step S28, the obtained degree of coincidence in the vector direction is calculated, and the process proceeds to step S29. The degree of coincidence is the degree of coincidence when four vector directions are compared, and the degree of coincidence increases as the degree of coincidence increases. The degree of coincidence can be calculated, for example, from the angle between the two vector directions as follows. The degree of coincidence between the two vector directions increases as the angle between the vectors decreases. In the case of four vectors, since there are six combinations for selecting two vector directions from the four vector directions, the angle formed by the six vector directions is calculated, and the combination having the largest angle is used as an index of the degree of coincidence. Good. Further, for example, angles formed by six sets of vector directions may be calculated, and the total value may be used as an index of the degree of coincidence.

  In step S29, it is determined whether or not the calculated degree of coincidence is equal to or greater than a predetermined threshold. If it is equal to or greater than the threshold, the process proceeds to step S210. If not, the process proceeds to step S211. As shown in FIG. 9, since the four vector directions in the specific range 21 are known, the threshold value of the degree of coincidence can be set from the known data. If the degree of coincidence is not equal to or greater than the threshold value, it is unlikely that the position is within the specific range 21. Therefore, it is determined that the existence position estimated by the RSSI distance relationship 135 is correct, and no correction is required.

  In step S210, since the degree of coincidence is equal to or greater than the threshold, the location is corrected to be within the specific range 21, and the process proceeds to step S211. The position after the correction is a predetermined position in the specific range 21, for example, a center position of the specific range 21.

  In step S211, the existence position calculated in step S25 or the existence position corrected in step S210 is determined as the final existence position, and the flow ends.

  As described above, when the position estimated by the electronic key 200 is within the difficult range 22 in which the position is difficult to be estimated based on the magnitude of the RSSI, the degree of coincidence of the direction of the magnetic field vector is compared with a threshold to determine whether the estimated position should be corrected. Judge. When the degree of coincidence is equal to or larger than the threshold, it is estimated that the electronic key 200 exists within the specific range 21.

  As described above, the electronic key position estimating system 10 of the present embodiment first estimates the position where the electronic key 200 exists using RSSI. Since there is a correlation between the RSSI and the distance between the LF antenna 181 and the electronic key 200, the position where the electronic key 200 exists is estimated using the magnitude of the RSSI of the radio waves from the four LF antennas 181. As described above, the position where the electronic key 200 exists can be estimated using the RSSI, but there is a specific range 21 whose estimation accuracy is low due to environmental factors.

  Since such a specific range 21 is determined by the position of a conductor, for example, a metal body of the vehicle 11, when the position estimated by RSSI is within a predetermined difficult range 22 that is difficult to estimate by RSSI, the position estimated by RSSI Is corrected using the direction of the magnetic field vector.

  Since the specific range 21 is surrounded by a conductor, the directions of the magnetic field vectors are easily aligned as shown in FIG. 5 and the like, and the degree of coincidence between the directions of the magnetic field vectors from the respective LF antennas 181 is high. Therefore, when the position estimated using the RSSI is within the difficult range 22, it is possible to estimate whether or not the position is within the difficult range 22 by using the degree of coincidence of the direction of the magnetic field vector.

  Then, the correction determining unit 123 determines whether or not to correct the position estimated using the degree of coincidence. If it is determined that the position should be corrected, the position correcting unit 125 determines that the electronic key 200 exists within the specific range 21. presume. Accordingly, even when it is estimated that the electronic key 200 exists in the difficult range 22 where the RSSI estimation accuracy is low, the electronic key 200 is corrected using the direction of the magnetic field vector, and the estimation accuracy of the position where the electronic key 200 is present is reduced. Can be improved.

  Focusing on the specific range 21 and the difficult range 22, the radio wave transmitted from the LF antenna 181 has a degree of coincidence of the direction of the magnetic field vector smaller than a predetermined value in the hard range 22 outside the specific range 21. . For example, as can be seen by comparing FIGS. 5 and 6, within the specific range 21, the directions of the magnetic field vectors are somewhat clockwise relative to each other. On the other hand, in the difficult range 22, the direction of the magnetic field vector diverges outward from the lower left corner in FIG. 5, and in FIG. 6, the direction of the magnetic field vector is clockwise as in the specific range 21. . Therefore, the degree of coincidence in the vector direction within the difficult range 22 is lower than the degree of coincidence in the vector direction within the specific range 21. Therefore, it can be easily determined whether or not it is within the difficult range 22 by comparing the degree of coincidence in the vector direction with a predetermined value. The predetermined value is a value set in advance, and is determined from actual data of the magnetic field vector.

  Further, in the present embodiment, the right LF antenna 181R and the left LF antenna 181L are arranged at intervals in the vehicle width direction. More specifically, the right LF antenna 181R and the left LF antenna 181L are arranged so as to sandwich the specific range 21. More specifically, two LF antennas 181 are arranged at both left and right ends of the vehicle 11. This makes it possible to increase the change in the vector direction in the difficult range 22 as compared with a configuration in which the LF antenna 181 is arranged in the specific direction 21 in the traveling direction of the vehicle 11.

  Specifically, the vector direction of the right LF antenna 181R shown in FIG. 5 and the vector direction of the left LF antenna 181L shown in FIG. This can be easily understood by comparing the vector directions of the front LF antenna 181F and the rear LF antenna 181B arranged in the front-rear direction as shown in FIGS. Therefore, by arranging the LF antennas 181 at intervals in the vehicle width direction, it is possible to determine with high accuracy whether the LF antenna 181 is within the more difficult range 22.

  Further, in the present embodiment, the rear LF antenna 181B is provided within the specific range 21, and the other three LF antennas 181 are provided outside the specific range 21. Therefore, since the LF antenna 181 is provided inside and outside the specific range 21, when estimating the position using the RSSI, it is easy to set a range where the estimation accuracy is difficult. That is, the RSSI from the three LF antennas 181 outside the specific range 21 is attenuated when the electronic key 200 is within the specific range 21, but the rear LF antenna 181B within the specific range 21 is affected by the attenuation. Is relatively difficult to receive. Therefore, when the electronic key 200 is present in the specific range 21, the detection area from the four LF antennas 181 is less likely to be mixed at one point in the process of estimating that the electronic key 200 is in the difficult range 22. In other words, the detection areas of the four LF antennas 181 become more dispersed. Therefore, it is easy to determine whether or not the correction should be performed, and the correction can improve the estimation accuracy.

  In such a case, it is preferable to make the determination in step S29 using a smaller low threshold. That is, when it is estimated that the vehicle is in the difficult range 22 based on the detection areas from the four LF antennas 181, it is considered that the possibility of actually existing in the difficult region 22 is low. Therefore, it is preferable to set the threshold value to a low threshold value so that it is easy to estimate that the threshold value exists in the specific range 21.

  In the present embodiment, the inside of the specific range 21 is the inside of the trunk room 12 at the rear of the vehicle 11. The trunk room 12 is a region surrounded by a metal member, and is a region where RSSI is easily attenuated. Even when the electronic key 200 is inside the trunk room 12, the position can be estimated as described above, so that it is erroneously detected that the electronic key 200 is outside the vehicle room despite being in the trunk room 12 inside the vehicle room. Can be prevented.

(Other embodiments)
As described above, the preferred embodiment has been described. However, the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the gist of the present disclosure.

  The structure of the above-described embodiment is merely an example, and the scope of the present disclosure is not limited to the scope of these descriptions. The scope of the present disclosure is shown by the description of the claims, and further includes all modifications within the meaning and scope equivalent to the description of the claims.

  In the above-described first embodiment, the positions of the LF antenna 181 are arranged at four predetermined positions, but are not limited thereto. The LF antenna 181 may be provided at any position as long as it is provided separately from the vehicle 11. However, it is preferable that the distance between the plurality of LF antennas 181 is greater. Further, the number of LF antennas 181 is not limited to four, but may be three or more.

  In the first embodiment described above, the electronic key 200 is disclosed as a portable device, but a portable device having no key function may be employed.

  In the first embodiment described above, the in-vehicle device 100 includes the LF antenna 181 that transmits the LF wave as the antenna that transmits the radio wave. However, the transmitted radio wave may be in a frequency band other than the LF wave. For example, an antenna that transmits an RF wave may be provided instead of the LF antenna 181.

  RF waves are sometimes called UHF waves. Specific frequencies of the RF wave include, for example, 315 Hz, 920 MHz, and 2.4 GHz. As a communication method using these frequencies, there is a communication method for executing pairing for authenticating each other in advance. For example, in Bluetooth (registered trademark), pairing is performed. Pairing between the on-vehicle device 100 and the electronic key 200 may be executable.

  In the first embodiment described above, the in-vehicle device 100 executes the position estimation processing. However, if the key-side control unit 230 includes the configuration of the vehicle-side control unit 120 and the in-vehicle device 100 notifies the electronic key 200 of the position of the LF antenna 181, the processing of FIG. You can also. The position of the LF antenna 181 is indicated by, for example, latitude and longitude. Further, since the on-vehicle device 100 and the electronic key 200 can communicate with each other, the electronic key 200 can execute only a part of the processing executed by the on-vehicle device 100.

  In the first embodiment described above, the position is estimated using all the RSSI information and vector information of the four LF antennas 181 (S28). However, the number is not limited to four. For example, the position may be estimated using vector information of two specific antennas among the four LF antennas 181, or the position may be estimated using three specific antennas.

  In the first embodiment described above, one LF antenna 181 of the four LF antennas 181 is provided in the specific range 21, but is not limited to this. All of the four LF antennas 181 may be provided outside the specific range 21. Further, at least one LF antenna 181 may be provided outside the specific range 21, and at least one LF antenna 181 may be provided inside the specific range 21.

  In the above-described first embodiment, the specific range 21 is the trunk room 12, but is not limited to the trunk room 12. As long as the space is surrounded by a metal material or the like so that the directions of the magnetic field vectors are aligned, the space may be, for example, the range of the rearmost seat of a three-row seat.

  In the first embodiment described above, the functions realized by the ECU such as the verification ECU 110 may be realized by hardware and software different from those described above, or a combination thereof. The ECU may communicate with another control device other than the electronic key 200, for example, and the other control device may execute a part or all of the processing. When the ECU is realized by an electronic circuit, it can be realized by a digital circuit including a large number of logic circuits, or an analog circuit.

  DESCRIPTION OF SYMBOLS 10 ... Electronic key position estimation system (portable device position estimation system) 11 ... Vehicle 12 ... Trunk room 21 ... Specific range 22 ... Difficult range 100 ... In-vehicle device (in-vehicle device) 110 ... Verification ECU (control unit) 120 ... Vehicle-side control unit 121 RSSI acquisition unit 122 Vector acquisition unit 123 Correction determination unit 124 Key area estimation unit 125 Position correction unit 180 Vehicle-side transmission unit 181 LF antenna (transmission antenna) 190 Vehicle-side reception unit 195 Vehicle-mounted RF antenna (receiving antenna) 200: electronic key (portable device) 210: key-side receiving unit 211: RSSI detecting circuit (detecting unit) 212: vector detecting circuit (detecting unit) 215: key-side RF antenna (sub receiving antenna) 220: key-side transmission unit 221: key-side LF antenna (sub-transmission antenna) 230: key-side control unit (sub-control unit)

Claims (5)

A portable device position estimation system (10) for performing wireless communication between an in-vehicle device (100) mounted on a vehicle and a portable device (200) carried by a user, and estimating a position where the portable device is present,
The in-vehicle device,
At least three transmitting antennas (181) for transmitting radio waves;
A receiving antenna (195) for receiving radio waves,
A control unit (110) for transmitting radio waves from the transmitting antenna and processing the radio waves received by the receiving antenna;
The portable device includes:
A sub-receiving antenna (215) for receiving radio waves from the transmitting antenna,
Detectors (211, 212) for detecting a received signal strength of a radio wave from each of the transmitting antennas received by the sub receiving antenna and a direction of a magnetic field vector of the radio wave from each of the transmitting antennas;
A sub-transmission antenna (221) for transmitting a radio wave to the reception antenna,
A sub-control unit (230) for transmitting a radio wave from the sub-transmission antenna and processing a radio wave received by the sub-reception antenna;
One of the control unit and the sub-control unit includes:
A position estimating unit (124) for estimating a position where the portable device is present, using magnitudes of the received signal strengths of radio waves from three or more transmitting antennas detected by the detecting unit;
When the position estimated by the position estimating unit is within the difficult range (22) where it is difficult to estimate the position only by the magnitude of the received signal strength, the magnetic field vector of the radio wave from two or more transmitting antennas A correction determining unit (123) that compares the degree of coincidence of the directions with a threshold value to determine whether to correct the position estimated by the position estimating unit;
A portable device including: a position correcting unit that corrects the position estimated by the position estimating unit to a specific range where the direction of the magnetic field vector is high in the matching degree when the degree of matching is equal to or greater than the threshold value in the correction determining unit. Position estimation system.   The portable device position estimating system according to claim 1, wherein at least two of the transmitting antennas are arranged at intervals in a vehicle width direction. The in-vehicle device includes four of the transmitting antennas for transmitting radio waves,
The four transmitting antennas are provided at different positions of the vehicle,
At least one of the transmitting antennas is provided outside the specific range;
At least one of the transmitting antennas is provided within the specific range,
When the position estimated by the position estimating unit is within the difficult range, the correction determining unit estimates using the coincidence of the directions of the magnetic field vectors of the four transmitting antennas detected by the detecting unit. Judge whether the corrected position should be corrected,
The said position correction part correct | amends the position estimated by the said position estimation part in the said specific range, when the said coincidence degree is more than the low threshold value smaller than the said threshold value in the said correction determination part. 3. The portable device position estimation system according to 1.   The portable device position estimating system according to claim 1, wherein the sub-control unit estimates and corrects the position.   The portable device position estimating system according to any one of claims 1 to 4, wherein the specific range is a trunk room (12) at a rear portion of the vehicle.

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