JP2021099289A - Communication device for vehicle - Google Patents

Abstract

To provide a communication device for a vehicle capable of expanding an area for specifying a position of a portable device.SOLUTION: An on-vehicle trigger radio device 1 transmits a trigger signal for starting UWB communication, and a portable trigger radio device 4 receives the trigger signal. When the portable trigger radio device 4 receives the trigger signal, a portable UWB radio device 5 transmits a UWB radio wave. On-vehicle UWB radio devices 2 are installed on a vehicle 6 by three of more units and receive the UWB radio wave. Control units 3 and 21 calculate a first radio wave coming direction from a time difference ΔT1 obtained by differentiating radio wave arriving time points of the plurality of on-vehicle UWB radio devices 2 in a prescribed combination. The control units 3 and 21 calculate a second radio wave coming direction from a time difference ΔT2 obtained by differentiating radio wave arriving time points of the plurality of on-vehicle UWB radio devices 2 in another combination. Further, the control units 3 and 21 specify the position of a portable device 8 on the basis of the cross point of the first radio wave coming direction and the second radio wave coming direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle communication device that identifies the position of a portable device held by a person.

Conventionally, various devices have been developed for identifying the position of a portable device held by a person by wireless communication. As such an apparatus, there is one described in Patent Document 1. The position-identifying device described in Patent Document 1 installs a reference station and a relay station in a service area, and identifies the position of the portable device by radio waves transmitted from the reference station and the relay station to the portable device.

Japanese Unexamined Patent Publication No. 2011-117879

However, the device of Patent Document 1 is a technique for specifying the position of a portable device by installing a reference station and a relay station at a distance from each other in a wide environment such as a service area. On the other hand, vehicle communication devices such as smart entry (registered trademark) that specify the position of a portable device with respect to a vehicle are a technology for specifying the position of a portable device with respect to a vehicle by mounting a radio in a limited space inside the vehicle. Is. Therefore, it is difficult to apply the technique of Patent Document 1 to the technique of a vehicle communication device. In a vehicle communication device, a radio is installed in a limited space inside the vehicle. Therefore, when a human body exists between the radio installed in the vehicle and a portable device owned by a person, the human body blocks radio waves. As a result, the received power is reduced, and there is a problem that the area where the position of the portable device can be specified is narrowed.

In view of the above points, it is an object of the present invention to expand the area in which the position of the portable device can be specified in the vehicle communication device.

In order to achieve the above object, the invention according to claim 1 is a vehicle communication for specifying the position of the portable device (8) with respect to the vehicle (6) by using ultra-wideband (hereinafter referred to as “UWB”) communication. The device includes an in-vehicle trigger radio (1), a portable trigger radio (4), a portable UWB radio (5), an in-vehicle UWB radio (2), and a control unit (3, 21). The in-vehicle trigger radio is mounted on the vehicle and transmits a trigger signal for starting UWB communication. The portable trigger radio is mounted on a portable device that can be carried by a person (7), and receives a trigger signal transmitted by the vehicle-mounted trigger radio. The portable UWB radio is mounted on the portable device, and when the portable trigger radio receives a trigger signal, it transmits a UWB radio wave. Three or more in-vehicle UWB radios are mounted on the vehicle and receive UWB radio waves transmitted by the portable UWB radio. The control unit calculates the first radio wave arrival direction from the time obtained by differentiating the radio wave arrival times received by each of the plurality of in-vehicle UWB radios in a predetermined combination of the UWB radio waves transmitted by the portable UWB radio. Further, the control unit calculates the second radio wave arrival direction from the time obtained by differentiating the radio wave arrival times received by the plurality of in-vehicle UWB radios by different combinations of the UWB radio waves transmitted by the portable UWB radio. Then, the control unit specifies the position of the portable device based on the intersection of the first radio wave arrival direction and the second radio wave arrival direction.

According to this, when the mobile trigger radio receives the trigger signal transmitted by the vehicle-mounted trigger radio, the UWB radio wave is transmitted from the mobile UWB radio. The control unit calculates the arrival direction of the UWB radio wave for each of the plurality of vehicle-mounted UWB radio waves by using only the UWB radio wave transmitted by the portable UWB radio wave and received by the plurality of vehicle-mounted UWB radio waves, and the plurality of radio waves. It is possible to identify the position of the portable device based on the intersection in the direction of arrival. Here, the decrease in the received power due to the antenna gain of the in-vehicle UWB radio is very small as compared with the decrease in the received power due to the antenna gain of the portable UWB radio. Therefore, if the output of the UWB radio wave transmitted by the mobile UWB radio and the output of the UWB radio wave transmitted by the vehicle-mounted UWB radio are the same, the received power of the UWB radio wave received by the vehicle-mounted UWB radio is the mobile UWB. It is larger than the received power of the UWB radio wave received by the radio. Therefore, this vehicle communication device calculates the direction of arrival of radio waves using only UWB radio waves with high received power received by the in-vehicle UWB radio, and thus the UWB radio waves are shielded by the human body or the like, resulting in communication problems. Can be improved and the area where the position of the portable device can be identified can be expanded.

The reference reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is a figure which shows the schematic structure of the vehicle communication apparatus which concerns on 1st Embodiment. It is a flowchart of the position identification processing of a portable device by a vehicle communication device. It is explanatory drawing for demonstrating the position identification processing of a portable device by a vehicle communication device. It is explanatory drawing for demonstrating the position identification processing of a portable device by a vehicle communication device. It is a figure which shows the condition of the experiment which measured the shielding effect of the UWB radio wave by the human body. It is a graph which shows the result of the experiment which measured the shielding effect of the UWB radio wave by the human body. It is a figure which shows the condition of the experiment which measured the passage characteristic of the human body of UWB radio wave. It is a graph which shows the result of the experiment which measured the passage characteristic of the human body of UWB radio wave. It is a figure which showed the difference of received power in the wireless line design of a UWB radio. It is a figure which shows the schematic structure of the vehicle communication device which concerns on 2nd Embodiment. It is a flowchart of individual difference correction processing of a plurality of in-vehicle UWB radios. It is explanatory drawing of the individual difference correction processing of a plurality of in-vehicle UWB radios. It is a figure which shows the schematic structure of the vehicle communication apparatus which concerns on 3rd Embodiment. It is a flowchart of the position identification processing of a portable device by the vehicle communication device of 3rd Embodiment. It is a flowchart of individual difference correction processing of a plurality of in-vehicle UWB radios. It is explanatory drawing of the individual difference correction processing of a plurality of in-vehicle UWB radios. It is a figure which shows the schematic structure of the vehicle communication apparatus which concerns on 4th Embodiment. It is a flowchart of individual difference correction processing of a plurality of in-vehicle UWB radios. It is a flowchart of the position identification processing of a portable device in 4th Embodiment. It is explanatory drawing for demonstrating bidirectional distance measurement in individual difference correction processing of a plurality of in-vehicle UWB radios. It is explanatory drawing for demonstrating bidirectional distance measurement in individual difference correction processing of a plurality of in-vehicle UWB radios. It is explanatory drawing for demonstrating unidirectional distance measurement in individual difference correction processing of a plurality of vehicle-mounted UWB radios. It is explanatory drawing for demonstrating unidirectional distance measurement in individual difference correction processing of a plurality of vehicle-mounted UWB radios.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the same or equal parts are designated by the same reference numerals, and the description thereof will be omitted.

(First Embodiment)
The first embodiment will be described with reference to the drawings. The vehicle communication device of the present embodiment is a system for identifying the position of a portable device by using ultra-wideband (hereinafter referred to as "UWB") communication. UWB communication is a wireless communication method that uses a wide band frequency and can perform highly accurate position detection by short pulsed radio waves.

First, the configuration of the vehicle communication device will be described. As shown in FIG. 1, the vehicle communication device includes an in-vehicle trigger radio 1, an in-vehicle UWB radio 2, an electronic control device 3, a portable trigger radio 4, a mobile UWB radio 5, and the like.
The vehicle-mounted trigger radio 1, the vehicle-mounted UWB radio 2, and the electronic control device 3 are mounted on the vehicle 6. On the other hand, the portable trigger radio 4 and the portable UWB radio 5 are mounted on a portable device 8 that can be carried by a person 7. The portable device 8 is, for example, a smartphone.

The vehicle-mounted trigger radio 1 mounted on the vehicle 6 can transmit a trigger signal for starting UWB communication. The vehicle-mounted trigger radio 1 transmits a trigger signal, for example, when the door of the vehicle 6 is locked.

On the other hand, the portable trigger radio 4 mounted on the portable device 8 can receive the trigger signal transmitted by the vehicle-mounted trigger radio 1. In the present embodiment, both the vehicle-mounted trigger radio 1 and the mobile trigger radio 4 employ a BLE radio that communicates by Bluetooth Low Energy (hereinafter referred to as "BLE"). Therefore, BLE is used as a trigger signal.
When the portable trigger radio 4 receives the trigger signal, the portable trigger radio 4 transmits the information to the portable UWB radio 5 mounted on the same mobile device 8. The mobile UWB radio 5 is configured to transmit UWB radio waves when the information received from the trigger signal is transmitted from the mobile trigger radio 4.

Three or more in-vehicle UWB radios 2 are mounted on the vehicle 6. The in-vehicle UWB radio 2 can receive the UWB radio waves transmitted by the portable UWB radio 5. In the following description, the three in-vehicle UWB radios 2 shown in FIG. 1 and the like may be referred to as a first station 2a, a second station 2b, and a third station 2c, respectively, as necessary. That is, the plurality of vehicle-mounted UWB radios 2 are configured to include at least the first station 2a, the second station 2b, and the third station 2c. In FIG. 1 and the like, the first station 2a, the second station 2b, and the third station 2c are arranged in a straight line, but the arrangement of the plurality of in-vehicle UWB radios 2 is not limited to this, and is from the vertical direction. It suffices if they are arranged apart from each other when viewed.

Each of the plurality of vehicle-mounted UWB radios 2 has an integrated circuit (hereinafter referred to as "IC") and an internal clock, and can measure the arrival time of the radio wave that received the UWB radio wave. When a plurality of vehicle-mounted UWB radios 2 receive UWB radio waves, information regarding the arrival time of the radio waves is transmitted to the electronic control device 3 via a signal cable 9 or the like.

The electronic control device 3 is composed of a CPU that performs control processing and arithmetic processing, a microcomputer that includes a storage unit such as a ROM and a RAM that stores programs and data, and peripheral circuits thereof. The electronic control device 3 performs various control processes and arithmetic processes based on the program stored in the storage unit, and controls the operation of each device connected to the output port.

In the first embodiment, the electronic control device 3 corresponds to an example of the "control unit" described in the claims. The electronic control device 3 is the first radio wave arrival direction from the time obtained by differentiating the radio wave arrival times of the UWB radio waves received by the plurality of vehicle-mounted UWB radios 2 (for example, the first station 2a and the second station 2b) in a predetermined combination. Is calculated. Further, the electronic control device 3 is a second radio wave from the time obtained by differentiating the arrival times of the UWB radio waves received by a plurality of in-vehicle UWB radios 2 (for example, the second station 2b and the third station 2c) by different combinations. Calculate the direction of arrival. Then, the electronic control device 3 can specify the position of the portable device 8 based on the intersection of the first radio wave arrival direction and the second radio wave arrival direction.

Further, in the electronic control device 3, based on the position information of the specified portable device 8, whether the portable device 8 exists on the driver's seat side of the vehicle 6 or the portable device 8 exists on the passenger seat side of the vehicle 6. , It is determined whether or not the portable device 8 exists on the rear side of the vehicle 6. Then, the electronic control device 3 can unlock only the door near the position where the portable device 8 exists.

Next, the position identification process of the portable device 8 by the vehicle communication device will be described with reference to the flowchart of FIG.

In the position identification process of the portable device 8, in step S10, the vehicle-mounted trigger radio 1 transmits a trigger signal for starting UWB communication.
Next, in step S20, the portable trigger radio 4 receives the trigger signal transmitted by the vehicle-mounted trigger radio 1. Then, when the portable trigger radio 4 receives the trigger signal, the portable trigger radio 4 transmits the information to the mobile UWB radio 5.

Subsequently, in step S30, the mobile UWB radio 5 transmits a UWB radio wave when the information received from the mobile trigger radio 4 is transmitted.
Next, in step S40, a plurality of in-vehicle UWB radios 2 (for example, first station 2a, second station 2b, third station 2c) receive UWB radio waves. The plurality of vehicle-mounted UWB radios 2 transmit information regarding the arrival time of the radio wave that received the UWB radio wave to the electronic control device 3.

Subsequently, in step S50, the electronic control device 3 calculates the time obtained by differentiating the arrival times of the UWB radio waves received by the plurality of vehicle-mounted UWB radios 2. Then, in step S60, the electronic control device 3 calculates the radio wave arrival direction from the difference time. The processing of steps S50 and S60 will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, the electronic control device 3 calculates the time ΔT1 obtained by subtracting the arrival time of the UWB radio wave received by the first station 2a and the arrival time of the UWB radio wave received by the second station 2b, and the time ΔT1 is calculated. From ΔT1, the radio wave arrival direction with respect to the second station 2b is calculated. In the present embodiment, the radio wave arrival direction with respect to the second station 2b is referred to as the first radio wave arrival direction.

In FIG. 3, the line segment connecting the portable UWB radio 5 and the first station 2a is referred to as a line segment A. The line segment connecting the portable device 8 and the second station 2b is defined as a line segment B. Let the line segment connecting the first station 2a and the second station 2b be the line segment C. A line segment drawn perpendicularly to the line segment C from the first station 2a is defined as a line segment D. Let the line segment from the intersection E of the line segment D and the line segment B to the second station 2b be the line segment F. At this time, the distance of the line segment F is the propagation speed of the radio wave with respect to the time ΔT1 which is the difference between the arrival time of the UWB radio wave received by the first station 2a and the arrival time of the UWB radio wave received by the second station 2b. Hereinafter, it corresponds to the value multiplied by (referred to as "speed of light"). Therefore, if the angle formed by the line segment B and the line segment C is θ1 and the distance of the line segment C is X, the following equation 1 holds.

cos θ1 = (ΔT1 × speed of light) / X ... (Equation 1)
From this equation 1, the electronic control device 3 can calculate the angle θ1 formed by the line segment B and the line segment C. The angle θ1 formed by the line segment B and the line segment C corresponds to the above-mentioned first radio wave arrival direction.

Further, as shown in FIG. 4, the electronic control device 3 measures the time ΔT2 which is the difference between the arrival time of the UWB radio wave received by the second station 2b and the arrival time of the UWB radio wave received by the third station 2c. From that time ΔT2, the direction of arrival of radio waves with respect to the third station 2c is calculated. In the present embodiment, the direction of arrival of radio waves with respect to the third station 2c is referred to as the direction of arrival of second radio waves.

In FIG. 4, the line segment connecting the portable UWB radio 5 and the third station 2c is referred to as a line segment G. Let the line segment connecting the second station 2b and the third station 2c be the line segment H. A line segment drawn perpendicular to the line segment G from the second station 2b is defined as a line segment I. Let the line segment from the intersection J of the line segment I and the line segment G to the third station 2c be the line segment K. At this time, the distance of the line segment K is the value obtained by multiplying the time ΔT2, which is the difference between the arrival time of the UWB radio wave received by the second station 2b and the arrival time of the UWB radio wave received by the third station 2c, by the speed of light. Equivalent to. Therefore, if the angle formed by the line segment B and the line segment G is θ2 and the distance of the line segment H is Y, the following equation 2 holds.

cos θ2 = (ΔT2 × speed of light) / Y ・ ・ ・ (Equation 2)
From this equation 2, the electronic control device 3 can calculate the angle θ2 formed by the line segment H and the line segment G. The angle θ2 formed by the line segment H and the line segment G corresponds to the above-mentioned second radio wave arrival direction.

Subsequently, in step S70, the electronic control device 3 is mounted with the portable UWB radio 5 based on the intersections of a plurality of calculated radio wave arrival directions (for example, the first radio wave arrival direction and the second radio wave arrival direction). The position of the portable device 8 is specified. Specifically, as shown in FIG. 4, the electronic control device 3 can specify the position of the portable device 8 by calculating the intersection of the line segment B and the line segment G.

Next, regarding the significance of the vehicle communication device of the present embodiment specifying the position of the portable device 8 using only the UWB radio waves transmitted by the portable UWB radio 5 and received by the plurality of vehicle-mounted UWB radios 2. explain.

FIG. 5 is a diagram showing the conditions of an experiment in which the shielding effect of UWB radio waves by the human body was measured, and FIG. 6 is a graph showing the results of the experiment.
As shown in FIG. 5, in this experiment, the portable device 8 was placed in the right buttock pocket of the trousers worn by the subject 10, and the receiver 11 was placed at a distance of 1 m from the subject 10. Then, while the subject 10 rotated 360 ° at the same place, the distance measurement values between the portable device 8 and the receiver 11 were measured by the UWB radio waves transmitted from the portable device 8.

As shown in the graph of FIG. 6, in this experiment, when the state in which the subject 10 was facing the receiver 11 was set to 0 °, the distance could not be measured when the subject 10 was facing 0 ° to 75 °. .. It is considered that this is because when the subject 10 is facing 0 ° to 75 °, the human body exists between the portable device 8 and the receiver 11, and the shielding effect of the UWB radio wave is increased. Be done.

Subsequently, FIG. 7 is a diagram showing the conditions of the experiment in which the passage characteristics of the UWB radio wave of the human body were measured, and FIG. 8 is a graph showing the results of the experiment.
As shown in FIG. 7, in this experiment, a network analyzer 12 was used, the transmitting antenna 13 was placed in the right buttock pocket of the pants worn by the subject 10, and the receiving antenna 14 was placed at a distance of 1 m from the subject 10. .. Then, while the subject 10 rotated 360 ° at the same place, the passing characteristics of the UWB radio wave between the transmitting antenna 13 and the receiving antenna 14 were measured.

In the graph of FIG. 8, the state where the received power is the minimum is shown by a solid line, and the state where the received power is the maximum is shown by a broken line. As shown by the solid line in the graph of FIG. 8, when the state in which the subject 10 faces the receiver 11 is 0 °, it is stable when the subject 10 includes 0 ° and faces 315 ° to 105 °. The received power may be lower than the standard value (for example, -65 dB) that can be measured. As described above, when the UWB radio wave is shielded by the human body and the received power is lower than the reference value that enables stable distance measurement, stable distance measurement becomes impossible. From this experimental result, it can be said that by increasing the received power by, for example, 10 dB, the influence of UWB radio wave shielding by the human body can be avoided and distance measurement becomes possible.

In view of the above-mentioned experimental results, the vehicle communication device of the present embodiment receives only the UWB radio waves transmitted by the mobile UWB radio 5 and received by the plurality of vehicle-mounted UWB radios 2 in the position identification process of the mobile device 8. The method used is adopted. This is because the received power can be increased by adopting this method. The reason will be explained below.

FIG. 9 shows the received power when the mobile UWB radio wave 5 receives the UWB radio wave transmitted by the vehicle-mounted UWB radio wave 2 and the UWB radio wave transmitted by the vehicle-mounted UWB radio wave 2 when the mobile UWB radio wave 5 receives the UWB radio wave. It shows the difference from the received power.

FIG. 9A shows the received power when the mobile UWB radio 5 receives the UWB radio wave transmitted by the vehicle-mounted UWB radio 2. On the other hand, FIG. 9B shows the received power when the vehicle-mounted UWB radio 2 receives the UWB radio wave transmitted by the mobile UWB radio 5.

In general, the output of UWB radio waves transmitted from a UWB radio must be within the range stipulated by law. Therefore, the output of the UWB radio wave transmitted by the in-vehicle UWB radio 2 in FIG. 9A and the output of the UWB radio wave transmitted by the mobile UWB radio 5 in FIG. 9B are stipulated by law. It shall be the same within the range (for example, the upper limit).

In that case, as shown in FIG. 9A, the received power of the portable UWB radio 5 is attenuated by the distance attenuation, the attenuation due to the radio wave shielding of the human body, and the portable UWB radio from the transmission output of the vehicle-mounted UWB radio 2. It is attenuated by the antenna gain of 5.

On the other hand, as shown in FIG. 9B, the received power of the in-vehicle UWB radio 2 is attenuated by the radio wave shielding of the human body, the distance attenuation, and the in-vehicle UWB radio 2 from the transmission output of the portable UWB radio 5. It is attenuated by the antenna gain of.

Here, it is possible to use an antenna of the vehicle-mounted UWB radio 2 that is larger than the antenna of the portable UWB radio 5. Therefore, the decrease in the received power due to the antenna gain of the in-vehicle UWB radio 2 is much smaller than the decrease in the received power due to the antenna gain of the portable UWB radio 5. In FIGS. 9A and 9B, the decrease in the received power due to the antenna gain of the in-vehicle UWB radio 2 is set to, for example, 0 dBi, and the decrease in the received power due to the antenna gain of the portable UWB radio 5 is set to, for example, 10 dBi. In that case, the portable UWB radio 5 shown in FIG. 9 (B) is compared with the received power transmitted by the vehicle-mounted UWB radio 2 shown in FIG. 9 (A) and received by the mobile UWB radio 5. The received power transmitted and received by the vehicle-mounted UWB radio 2 is increased by, for example, 10 dBi. For this reason, the vehicle communication device adopts a method of using only the UWB radio waves transmitted by the mobile UWB radio 5 and received by the plurality of in-vehicle UWB radios 2 in the position identification process of the mobile device 8, and receives power. Is high.

The vehicle communication device of the present embodiment described above has the following effects.
(1) In the present embodiment, a method of specifying the position of the portable device 8 by using only the UWB radio waves transmitted by the portable UWB radio 5 and received by the plurality of vehicle-mounted UWB radios 2 is adopted. Therefore, the vehicle communication device calculates the radio wave arrival direction using only the UWB radio wave having high received power, thereby improving the communication problem caused by the UWB radio wave being shielded by the human body or the like, and the portable device 8 The area where the position can be specified can be expanded.

(2) In the present embodiment, the BLE radio is adopted as both the vehicle-mounted trigger radio 1 and the portable trigger radio 4. According to this, by using the BLE mounted on the conventional smartphone, it is possible to reasonably realize the portable trigger radio 4 mounted on the portable device 8. Further, by using BLE having a characteristic of being hard to be shielded by a human body or the like as a trigger signal, UWB communication can be reliably started when the portable device 8 is in a predetermined range around the vehicle 6.

(3) In the present embodiment, the electronic control device 3 is placed on the driver's seat side of the vehicle 6 based on the position information of the portable device 8 specified by the intersection of the first radio wave arrival direction and the second radio wave arrival direction. It is determined whether the portable device 8 exists, the portable device 8 exists on the passenger seat side of the vehicle 6, or the portable device 8 exists on the rear side of the vehicle 6. According to this, by specifying the position of the portable device 8 with respect to the vehicle 6, the door at the position where the portable device 8 exists can be unlocked, and the door at the place where the portable device 8 does not exist can be prevented from unlocking. it can.

(Second Embodiment)
Next, the second embodiment will be described. Similar to the first embodiment, the vehicle communication device of the second embodiment also includes an in-vehicle trigger radio 1, an in-vehicle UWB radio 2, an electronic control device 3, a mobile trigger radio 4, a mobile UWB radio 5, and the like. Is provided. Then, also in the second embodiment, the position of the portable device 8 is specified by calculating the first radio wave arrival direction and the second radio wave arrival direction in the same manner as in the first embodiment described above.
However, when the vehicle communication device performs the process of identifying the position of the portable device 8, if the internal clocks of the plurality of in-vehicle UWB radios 2 are not synchronized with each other, the position of the portable device 8 can be determined with high accuracy. It becomes difficult to identify. Therefore, in the second embodiment, a method of calculating the correction value used when performing the calculation for specifying the position of the portable device 8 will be described.

In FIG. 10, among the configurations included in the vehicle communication device of the second embodiment, only three in-vehicle UWB radios 2 and an electronic control device 3 are shown, and the other configurations are not shown. .. Also in the description of the second embodiment, if necessary, the three in-vehicle UWB radios 2 shown in FIG. 10 may be referred to as a first station 2a, a second station 2b, and a third station 2c, respectively. In the second embodiment, it is assumed that the first station 2a, the second station 2b, and the third station 2c are arranged substantially linearly in this order. The plurality of vehicle-mounted UWB radios 2 have an IC and an internal clock. As an individual difference, the plurality of in-vehicle UWB radios 2 may have slightly out of sync with the internal clocks of the first station 2a, the second station 2b, and the third station 2c. Further, as an individual difference, the plurality of vehicle-mounted UWB radios 2 may have slightly different delay times due to the signal cable 9 connecting the plurality of vehicle-mounted UWB radios 2 and the electronic control device 3. In view of such a problem, a process for correcting individual differences of a plurality of in-vehicle UWB radios 2 will be described below.

The individual difference correction processing of the plurality of vehicle-mounted UWB radios 2 will be described with reference to the flowchart of FIG. 11 and the explanatory diagram of FIG. The horizontal axis of FIG. 12 represents the time axis.

In the individual difference correction process, in step S110, the third station 2c transmits UWB radio waves.
Next, in step S120, the first station 2a and the second station 2b each receive the UWB radio waves transmitted by the third station 2c. The first station 2a and the second station 2b each transmit information regarding the arrival time of the radio wave that received the UWB radio wave to the electronic control device 3.

Subsequently, in step S130, the electronic control device 3 corrects the position of the portable device 8 based on the arrival time of the radio waves received by the first station 2a and the second station 2b, respectively. Calculate the value.
Specifically, as shown in FIG. 12, the electronic control device 3 sets the radio wave arrival time S1 of the UWB radio wave received by the first station 2a and the radio wave arrival time S2 of the UWB radio wave received by the second station 2b. The difference time ΔT3 is calculated. The value obtained by multiplying the time ΔT3 by the speed of light corresponds to the distance between the first station 2a and the second station 2b. However, the distance between the first station 2a and the second station 2b calculated in this way is an error between the internal clock of the first station 2a and the internal clock of the second station 2b, or a plurality of in-vehicle UWB radios. It includes an error in the delay time due to the signal cable 9 connecting the 2 and the electronic control device 3, respectively.

Here, in the second embodiment, accurate distance information between the first station 2a and the second station 2b is stored in advance with respect to the storage unit of the electronic control device 3, for example, in the manufacturing process. And. Let X be the exact distance between the pre-stored first station 2a and the second station 2b. At this time, the following equation 2 holds.

(ΔT3 x speed of light) x correction value = X ... (Equation 2)
Based on this equation 2, the electronic control device 3 can calculate a correction value to be used when performing a calculation for specifying the position of the portable device 8. Using this correction value, it is possible to replace the equation 1 described in the first embodiment with the following equation 3.

cos θ1 = (ΔT1 x speed of light x correction value) / X ... (Equation 3)
From this equation 3, the electronic control device 3 can accurately calculate the first radio wave arrival direction (that is, the angle θ1 formed by the line segment B and the line segment C shown in FIG. 3).
The electronic control device 3 can also accurately calculate the second radio wave arrival direction by the same method as described above.

In the second embodiment described above, even if the internal clocks of the plurality of vehicle-mounted UWB radios 2 are not synchronized or there is a difference in the delay time due to the signal cable 9, the correction value calculated by the above method is used. Can be used to identify the position of the portable device 8 with high accuracy.

(Third Embodiment)
Next, the third embodiment will be described. Similar to the first embodiment, the vehicle communication device of the third embodiment also includes the vehicle-mounted trigger radio 1, the vehicle-mounted UWB radio 2, the electronic control device 3, the portable trigger radio 4, and the mobile UWB radio 5. And so on. However, FIG. 13 shows only three in-vehicle UWB radios 2 and an electronic control device 3 among the configurations included in the vehicle communication device of the third embodiment, and the illustration of other configurations is omitted. ing. Also in the third embodiment, it is assumed that the first station 2a, the second station 2b, and the third station 2c are arranged substantially linearly in this order.

In the third embodiment, the in-vehicle UWB radio 2 of the plurality of in-vehicle UWB radios 2 has the calculation of the first radio wave arrival direction and the second radio wave arrival direction instead of the electronic control device 3. I try to do it with IC. Therefore, in the third embodiment, the IC included in the in-vehicle UWB radio 2 corresponds to an example of the "control unit" described in the claims.

In the description of the third embodiment, it is assumed that the position identification process of the portable device 8 is performed by the IC possessed by the second station 2b among the plurality of in-vehicle UWB radios 2. However, the position identification process of the portable device 8 is not limited to the IC possessed by the second station 2b, and may be performed by the IC possessed by another in-vehicle UWB radio 2.

The position specifying process of the portable device 8 will be described with reference to the flowchart of FIG. In the flowchart of FIG. 14, only the first station 2a, the second station 2b, and the third station 2c are described among the plurality of in-vehicle UWB radios 2, but the same processing is performed in the other in-vehicle UWB radios 2. Will be.

In the flowchart of FIG. 14, the processes of steps S10 to S30 are the same as those described in the first embodiment, and thus the description thereof will be omitted.

In the third embodiment, in step S41, the plurality of vehicle-mounted UWB radios 2 (that is, the first station 2a, the second station 2b, and the third station 2c) each receive the UWB radio waves transmitted from the mobile UWB radio 5. To do. Then, in step S42, the first station 2a and the third station 2c each transmit UWB radio waves.

In step S43, the second station 2b receives the UWB radio waves transmitted from the first station 2a and the third station 2c, respectively. Then, in step S44, the IC possessed by the second station 2b calculates the arrival time of the UWB radio wave transmitted from the portable UWB radio 5 and received by the first station 2a as follows.

Let N1 be the arrival time of the UWB radio wave transmitted from the portable UWB radio 5 and received by the first station 2a. The time (hereinafter, referred to as relay processing time) required for the first station 2a to transmit the UWB radio wave after the first station 2a receives the UWB radio wave transmitted from the mobile UWB radio 5 is defined as ΔT4. Let ΔT5 be the time required for the UWB radio wave transmitted by the first station 2a to reach the second station 2b from the first station 2a. Let N2 be the arrival time of the radio wave received by the second station 2b from the UWB radio wave transmitted from the first station 2a. At this time, the following equation 4 holds.

N1 = N2-ΔT5-ΔT4 ... (Equation 4)

In the third embodiment, it is assumed that the accurate distance X between the first station 2a and the second station 2b is stored in advance with respect to the IC possessed by the second station 2b. Alternatively, accurate information on the distance X between the first station 2a and the second station 2b is stored in advance in the electronic control device 3, and the IC possessed by the second station 2b stores the information on the distance X in the electronic control device. It shall be possible to obtain from 3. Therefore, the time ΔT5 required for the UWB radio wave transmitted by the first station 2a to reach the second station 2b from the first station 2a is calculated by the following equation 5.

ΔT5 = X / speed of light ... (Equation 5)
If the relay processing time ΔT4 of the first station 2a is known, the IC possessed by the second station 2b uses the above equation 4 to set the radio wave arrival time N1 of the UWB radio wave transmitted from the portable UWB radio 5 and received by the first station 2a. It is possible to calculate based on Equation 5.

Further, the IC possessed by the second station 2b also calculates the arrival time of the radio wave received by the third station 2c from the UWB radio wave transmitted from the portable UWB radio 5 in the same manner as described above.
After that, the processing performed by the IC possessed by the second station 2b is the same as the processing performed by the electronic control device 3 described in steps S50 to S70 of the first embodiment, and thus the description thereof will be omitted.

Next, a method of calculating the relay processing time ΔT4 of the first station 2a will be described with reference to the flowchart of FIG. 15 and the explanatory diagram of FIG. The horizontal axis of FIG. 16 represents time.

In this method of calculating the relay processing time, in step S210, the third station 2c transmits UWB radio waves.
Next, in step S220, the second station 2b receives the UWB radio wave transmitted by the third station 2c. At that time, the second station 2b measures the radio wave arrival time N3 at which the UWB radio wave transmitted by the third station 2c is received by the internal clock of the second station 2b and stores it in the IC of the second station 2b. ..

In step S230, the first station 2a receives the UWB radio wave transmitted by the third station 2c. Then, in step S240, the first station 2a transmits a UWB radio wave.
In step S250, the second station 2b receives the UWB radio wave transmitted from the first station 2a. Then, the second station 2b measures the radio wave arrival time N4 at which the UWB radio wave transmitted by the second station 2b is received by the internal clock of the second station 2b and stores it in the IC of the second station 2b.

In step S260, the IC possessed by the second station 2b differs between the radio wave arrival time N3 that received the UWB radio wave transmitted by the first station 2a and the radio wave arrival time N4 that received the UWB radio wave transmitted by the third station 2c. Calculate the time ΔT6.
Subsequently, in step S270, the IC possessed by the second station 2b calculates the relay processing time ΔT4 of the first station 2a. The relay processing time ΔT4 of the first station 2a is obtained by the following equation 6.

(ΔT6-ΔT4) × speed of light = 2X ... (Equation 6)
The IC possessed by the second station 2b calculates the relay processing time ΔT4 of the first station 2a from the above equation 6.

As a result, the relay processing time ΔT4 of the first station 2a required in the formula 4 described in step S44 of the position specifying process of the portable device 8 described above is calculated. Therefore, the IC possessed by the second station 2b accurately calculates the radio wave arrival time N1 of the UWB radio wave transmitted from the portable UWB radio 5 and received by the first station 2a based on the above equations 4 and 5. It is possible.

The IC possessed by the second station 2b calculates the relay processing time of the third station 2c by the same method, and the arrival time of the UWB radio wave transmitted from the portable UWB radio 5 and received by the third station 2c. Is calculated. In this way, the IC possessed by the second station 2b can specify the position of the portable device 8 based on the intersection of the first radio wave arrival direction and the second radio wave arrival direction.

In the vehicle communication device of the third embodiment described above, the IC possessed by the vehicle-mounted UWB radio 2 of the plurality of vehicle-mounted UWB radios 2 determines the first radio wave arrival direction and the second radio wave arrival direction. calculate. Therefore, even when the internal clocks of the plurality of in-vehicle UWB radios 2 are not synchronized, the position of the portable device 8 can be specified with high accuracy. Further, the position of the portable device 8 can be specified with high accuracy without being affected by the difference in the delay time of the signal cables 9 connecting the plurality of in-vehicle UWB radios 2 and the electronic control device 3, respectively.

(Fourth Embodiment)
Next, the fourth embodiment will be described. As shown in FIG. 17, the vehicle communication device of the fourth embodiment also has the vehicle-mounted trigger radio 1, the vehicle-mounted UWB radio 2, the electronic control device 3, and the portable trigger radio, as in the first embodiment and the like. 4 and a portable UWB radio 5 and the like are provided. Each of the plurality of vehicle-mounted UWB radios 2 and the portable UWB radio 5 has an IC 21 and an internal clock 22 together with the transmitter / receiver 20. Then, also in the fourth embodiment, the position of the portable device 8 is specified by calculating the first radio wave arrival direction and the second radio wave arrival direction in the same manner as in the first embodiment described above. However, when the position of the portable device 8 is specified, if the internal clocks 22 of the plurality of in-vehicle UWB radios 2 are not synchronized with each other, it is difficult to specify the position of the portable device 8 with high accuracy. Become. Therefore, in the fourth embodiment, a method of correcting the error of the internal clock 22 possessed by each of the plurality of in-vehicle UWB radios 2 and synchronizing the internal clock 22 when performing the calculation for specifying the position of the portable device 8 will be described. To do.

The synchronization processing of the internal clock 22 of each of the plurality of vehicle-mounted UWB radios 2 will be described with reference to the flowchart of FIG. 18A and the explanatory views of FIGS. 19 to 22. Note that, in FIGS. 19 and 21, only two in-vehicle UWB radios 2 and an electronic control device 3 are shown among the configurations included in the vehicle communication device of the fourth embodiment, and other configurations are shown. Is omitted. In the description of the fourth embodiment, the two in-vehicle UWB radios 2 shown in FIGS. 19 and 21 may be referred to as a reference station 2d and a sub station 2e, respectively, as necessary. In addition, although FIG. 19 and FIG. 21 show one reference station 2d and one sub station 2e, in reality, a plurality of in-vehicle UWB radios 2 are referred to as sub stations 2e.

In the synchronization process of the internal clock 22 shown in the flowchart of FIG. 18A, steps S310 to S360 are processes for executing bidirectional distance measurement between the reference station 2d and the sub station 2e. On the other hand, steps S370 to S390 are processes for executing unidirectional distance measurement between the reference station 2d and the sub station 2e.

In bidirectional ranging, the reference station 2d transmits UWB radio waves in step S310. Then, the reference station 2d measures the time at which the UWB radio wave is transmitted by the internal clock 22d of the reference station 2d and stores it in the IC 21d of the reference station 2d.

Next, in step S320, the sub station 2e receives the UWB radio wave transmitted by the reference station 2d. Then, in step S330, the sub station 2e transmits a UWB radio wave. At that time, the sub station 2e measures the time taken from receiving the UWB radio wave transmitted by the reference station 2d to transmitting the UWB radio wave (that is, the relay processing time) by the internal clock 22e of the sub station 2e. The relay processing time data is added to the UWB radio wave transmitted by the sub station 2e.

Next, in step S340, the reference station 2d receives the UWB radio wave transmitted by the sub station 2e. As described above, the relay processing time data of the sub station 2e is added to the UWB radio wave.
Subsequently, in step S350, the reference station 2d measures the time when the UWB radio wave is received by the internal clock 22d of the reference station 2d, and stores it in the IC 21d of the reference station 2d. Further, the reference station 2d also stores the relay processing time data of the sub station 2e added to the UWB radio wave in the IC 21d of the reference station 2d.

Next, in step S360, the reference station 2d sets the reference station 2d and the sub station 2e based on the time when the UWB radio wave is transmitted, the time when the UWB radio wave is received, and the relay processing time of the sub station 2e stored in the IC 21d of the reference station 2d. The radio wave measurement distance with and is calculated as follows. In this specification, the radio wave measurement distance is a distance measured by radio waves.

As shown in FIG. 20, the time when the reference station 2d transmits the UWB radio wave in step S310 is N10. In step S340, the time when the reference station 2d receives the UWB radio wave is set to N20. Let ΔT7 be the relay processing time of the sub station 2e added to the UWB radio wave. Let X_two-way be the radio wave measurement distance between the reference station 2d and the sub station 2e. At this time, the following equation 7 holds.

(N20-N10-ΔT7) × speed of light / 2 = X_two-way ・ ・ ・ (Equation 7)
The radio wave measurement distance X_two-way between the reference station 2d and the sub station 2e calculated by this formula 7 is the distance that the UWB radio wave actually propagates in the environment where the reference station 2d and the sub station 2e are mounted on the vehicle 6. It was measured accurately.

Subsequently, in the unidirectional ranging, the reference station 2d transmits the UWB radio wave in step S370. At that time, the reference station 2d measures the time at which the UWB radio wave is transmitted by the internal clock 22d of the reference station 2d, and adds the transmission time data to the UWB radio wave transmitted by the reference station 2d for transmission.

Next, in step S380, the sub station 2e receives the UWB radio wave transmitted by the reference station 2d. At that time, the sub station 2e measures the time when the UWB radio wave is received by the internal clock 22e of the sub station 2e, and stores the reception time data in the IC 21e of the sub station 2e. Further, the sub station 2e stores the transmission time data added to the UWB radio wave in the IC 21e of the sub station 2e.

Subsequently, in step S390, the sub station 2e sets the radio wave measurement distance between the reference station 2d and the sub station 2e based on the transmission time data and the reception time data stored in the IC 21e of the sub station 2e as follows. calculate.
Specifically, as shown in FIG. 22, the time when the reference station 2d transmits the UWB radio wave in step S380 is set to N30. In step S390, the time when the sub station 2e receives the UWB radio wave is set to N40. Let X_one-way be the radio wave measurement distance between the reference station 2d and the sub station 2e. At this time, the following equation 8 holds.

(N40-N30) x speed of light = X_one-way ... (Equation 8)
The radio wave measurement distance X_one-way between the reference station 2d and the sub station 2e calculated by this formula 8 is the distance at which the UWB radio wave actually propagates in the environment where the reference station 2d and the sub station 2e are mounted on the vehicle 6. In addition, the distance calculated due to the error between the internal clock 22d of the reference station 2d and the internal clock 22e of the sub station 2e is included.

Next, in step S400, the electronic control device 3 is calculated by the radio wave measurement distance X_two-way between the reference station 2d and the sub station 2e calculated by bidirectional distance measurement in step S360, and by unidirectional distance measurement in step S390. The difference between the radio wave measurement distance X_one-way between the reference station 2d and the sub station 2e (that is, the distance difference ΔX) is calculated. Then, by dividing the calculated distance difference ΔX by the speed of light, the time error between the internal clock 22d of the reference station 2d and the internal clock 22e of the sub station 2e is calculated.
In step S410, the time error between the internal clock 22d of the reference station 2d and the internal clock 22e of the sub station 2e is corrected.

Steps S10 to S70 of the flowchart of FIG. 18B represent the position specifying process of the portable device 8. The processing of steps S10 to S70 is substantially the same as that described in the first embodiment. However, in the fourth embodiment, in the process of step S410 described above, the error of the internal clocks 22 of the plurality of in-vehicle UWB radios 2 is corrected and synchronized, and then the process of step S50 is performed. Therefore, the electronic control device 3 can accurately calculate the time obtained by differentiating the arrival times of the UWB radio waves received by the plurality of in-vehicle UWB radios 2. As a result, the electronic control device 3 can accurately calculate the direction of arrival of radio waves for each of the plurality of in-vehicle UWB radios 2, and can accurately determine the position of the portable device 8 based on the intersection.

In the description of the fourth embodiment described above, the reference station 2d and the sub station 2e are shown one by one, but in reality, a plurality of in-vehicle UWB radios 2 are referred to as the sub station 2e. In that case, it is preferable that the vehicle-mounted UWB radio 2 as the reference station 2d is provided in a place where communication with a plurality of vehicle-mounted UWB radios 2 as the sub station 2e is possible. As a result, the time error of the internal clocks 22 of the plurality of sub stations 2e can be detected with the minimum number of transmissions or in a short time.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the claims. Further, the above-described embodiments are not unrelated to each other, and can be appropriately combined unless the combination is clearly impossible. Further, in each of the above embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential except when it is clearly stated that they are essential and when they are clearly considered to be essential in principle. No. Further, in each of the above embodiments, when numerical values such as the number, numerical values, quantities, and ranges of the constituent elements of the embodiment are mentioned, when it is clearly stated that they are particularly essential, and in principle, they are clearly limited to a specific number. It is not limited to the specific number except when it is done. Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of a component or the like, the shape, unless otherwise specified or limited in principle to a specific shape, positional relationship, etc. It is not limited to the positional relationship.

For example, in each of the above embodiments, in the position specifying process of the portable device 8, the position of the portable device 8 is specified based on the intersection of the first radio wave arrival direction and the second radio wave arrival direction, but the present invention is not limited to this. In the position identification process of the portable device 8, a plurality of radio wave arrival directions may be calculated. For example, in addition to the first radio wave arrival direction and the second radio wave arrival direction, a third radio wave arrival direction and the like are calculated. The position of the portable device 8 may be specified based on the intersections thereof.

For example, in the fourth embodiment, the position identification process of the portable device 8 has been described as being performed by the electronic control device 3, but the present invention is not limited to this. The position identification process of the portable device 8 may be performed by the IC 21 of the vehicle-mounted UWB radio 2 among the plurality of vehicle-mounted UWB radios 2 as in the third embodiment.

(Summary)
According to the first aspect shown in part or all of the above-described embodiments, the vehicle communication device for identifying the position of the portable device with respect to the vehicle using UWB communication is for an in-vehicle trigger radio device or a portable trigger. It includes a radio, a portable UWB radio, an in-vehicle UWB radio, and a control unit. The in-vehicle trigger radio is mounted on the vehicle and transmits a trigger signal for starting UWB communication. The portable trigger radio is mounted on a portable device that can be carried by a person, and receives a trigger signal transmitted by the in-vehicle trigger radio. The portable UWB radio is mounted on the portable device, and when the portable trigger radio receives a trigger signal, it transmits a UWB radio wave. Three or more in-vehicle UWB radios are mounted on the vehicle and receive UWB radio waves transmitted by the portable UWB radio. The control unit calculates the first radio wave arrival direction from the time obtained by differentiating the radio wave arrival times received by each of the plurality of in-vehicle UWB radios in a predetermined combination of the UWB radio waves transmitted by the portable UWB radio. Further, the control unit calculates the second radio wave arrival direction from the time obtained by differentiating the radio wave arrival times received by the plurality of in-vehicle UWB radios by different combinations of the UWB radio waves transmitted by the portable UWB radio. Then, the control unit specifies the position of the portable device based on the intersection of the first radio wave arrival direction and the second radio wave arrival direction.

From the second point of view, the portable device is a smartphone. Both the in-vehicle trigger radio and the portable trigger radio are BLE radios that perform communication by BLE, and BLE is used as the trigger signal.
According to this, by using BLE mounted on a conventional smartphone, it is possible to reasonably realize a portable trigger radio mounted on a portable device. Further, by using BLE having a characteristic of being hard to be shielded by a human body or the like as a trigger signal, UWB communication can be reliably started when the portable device is in a predetermined range around the vehicle.

According to the third viewpoint, the control unit determines whether the portable device is present on the driver's seat side of the vehicle or on the passenger seat side of the vehicle based on the position information of the portable device specified by the intersection of a plurality of radio wave arrival directions. Determine if there is a portable device or if there is a portable device on the rear side of the vehicle.
According to this, by specifying the position of the portable device with respect to the vehicle, it is possible to unlock the door at the position where the portable device exists and prevent the door at the place where the portable device does not exist.

According to the fourth aspect, the plurality of in-vehicle UWB radios are configured to include a first station, a second station, and a third station. Information regarding the distance between the first station and the second station is stored in advance in the control unit. Then, the third station transmits UWB radio waves. The first station and the second station each receive UWB radio waves transmitted by the third station. The control unit has a value obtained by multiplying the time difference between the arrival times of UWB radio waves received by the first station and the second station by the propagation speed of the radio wave, and the first station and the second station stored in advance. From the ratio with the distance to the station, the correction value when performing the calculation to specify the position of the portable device is calculated.
According to this, even if the internal clocks of the multiple in-vehicle UWB radios are not synchronized or there is a difference in the delay time due to the signal cable, the position of the portable device can be determined using the correction value. It can be specified with high accuracy.

According to the fifth aspect, the plurality of in-vehicle UWB radios are configured to include a first station, a second station, and a third station. At least the second station has an integrated circuit (hereinafter referred to as "IC") and an internal clock, and the IC stores information on the distance between the first station and the second station in advance. There is. The third station transmits UWB radio waves. When the first station receives the UWB radio wave transmitted by the third station, the first station transmits the UWB radio wave. The time from when the first station receives the UWB radio wave to when the UWB radio wave is transmitted is called a relay processing time. The second station receives the UWB radio waves transmitted by the third station and the UWB radio waves transmitted by the first station, respectively. The IC possessed by the second station is stored in advance as the time obtained by the difference between the arrival time of the radio wave that received the UWB radio wave transmitted by the third station and the arrival time of the radio wave that received the UWB radio wave transmitted by the first station. The relay processing time of the first station is calculated based on the distance between the first station and the second station.
According to this, even when the internal clocks of the plurality of in-vehicle UWB radios are not synchronized, the position of the portable device can be specified with high accuracy by the IC of the second station.
From the fifth viewpoint, since the position of the portable device can be specified by the IC possessed by the second station, the influence of the delay time of the signal cable can be eliminated.

According to the sixth aspect, when the plurality of vehicle-mounted UWB radios receive the UWB radio waves transmitted by the portable UWB radios, they transmit the UWB radio waves. Among the plurality of in-vehicle UWB radios, the in-vehicle UWB radio having an IC and an internal clock receives the UWB radio waves transmitted by the portable UWB radio and the UWB radio waves transmitted from other in-vehicle UWB radios. Then, the IC of the in-vehicle UWB radio is configured to function as a control unit that calculates the first radio wave arrival direction and the second radio wave arrival direction and specifies the position of the portable device.
According to this, since the position of the portable device can be specified by the IC possessed by the in-vehicle UWB radio, the influence of the delay time of the signal cable can be eliminated.

According to the seventh aspect, the plurality of in-vehicle UWB radios are configured to include a reference station and a sub station. The reference station and the sub station each have an IC and an internal clock. The distance between the reference station and the sub station is measured by two-way communication, and the distance between the reference station and the sub station is measured by unidirectional communication. Then, based on the difference between the distance measured by the two-way communication and the distance measured by the one-way communication, the time error between the internal clock of the reference station and the internal clock of the sub station is calculated and corrected.
According to this, the distance measurement value by bidirectional communication is an accurate radio wave propagation distance in an in-vehicle environment without being affected by an error between the internal clock of the reference station and the internal clock of the sub station. On the other hand, the distance measurement value by unidirectional communication includes the distance corresponding to the error between the internal clock of the reference station and the internal clock of the sub station with respect to the radio wave propagation distance. Therefore, the difference between the distance calculated by bidirectional communication and the distance calculated by unidirectional communication is the distance corresponding to the error between the internal clock of the reference station and the internal clock of the sub station. Based on the result, the position of the portable device can be specified with high accuracy by synchronizing the internal clock of the reference station and the internal clock of the sub station.

According to the eighth viewpoint, the calculation of the distance between the reference station and the sub station by two-way communication is as follows. First, the reference station transmits a UWB radio wave and stores the transmission time of the UWB radio wave. The sub-station that has received the UWB radio wave transmitted by the reference station transmits the UWB radio wave by adding the relay processing time data from the reception of the UWB radio wave to the transmission of the UWB radio wave. The reference station that receives the UWB radio wave transmitted by the sub station stores the arrival time of the UWB radio wave and the relay processing time data added to the UWB radio wave. Then, the distance between the reference station and the sub station is based on the time obtained by subtracting the relay processing time data from the time from the transmission time when the reference station transmits the UWB radio wave to the arrival time of the radio wave received by the reference station for the UWB radio wave transmitted by the sub station. Is calculated.
On the other hand, the calculation of the distance between the reference station and the sub station by unidirectional communication is as follows. First, the reference station adds transmission time data and transmits UWB radio waves. The sub station that has received the UWB radio wave transmitted by the reference station stores the arrival time of the radio wave that received the UWB radio wave and the transmission time data added to the UWB radio wave. Then, the distance between the reference station and the sub station is calculated based on the time from the transmission time when the reference station transmits the UWB radio wave to the arrival time of the radio wave when the sub station receives the UWB radio wave.
According to this, a method of calculating the distance between the reference station and the sub station by bidirectional ranging and a method of calculating the distance between the reference station and the sub station by unidirectional ranging are specifically shown.

According to the ninth aspect, among the plurality of in-vehicle UWB radios, the in-vehicle UWB radio as a reference station is provided in a place where communication is possible with the plurality of in-vehicle UWB radios as sub stations. ..
According to this, the time error of the internal clock possessed by the plurality of in-vehicle UWB radios can be detected with the minimum number of transmissions or in a short time.

1 In-vehicle trigger radio 2 In-vehicle UWB radio 3 Electronic control device 4 Mobile trigger radio 5 Mobile UWB radio 6 Vehicle 7 people 8 Mobile 21 IC

Claims (9)

In a vehicle communication device that identifies the position of a portable device (8) with respect to a vehicle (6) using ultra-wideband (hereinafter referred to as "UWB") communication.
An in-vehicle trigger radio (1) mounted on the vehicle and transmitting a trigger signal for starting UWB communication, and
A portable trigger radio (4) mounted on the portable device that can be carried by a person (7) and receiving a trigger signal transmitted by the in-vehicle trigger radio.
A portable UWB radio (5) mounted on the portable device and transmitting a UWB radio wave when the portable trigger radio receives a trigger signal.
Three or more in-vehicle UWB radios (2) mounted on the vehicle and receiving UWB radio waves transmitted by the portable UWB radio, and
The first radio wave arrival direction is calculated from the time (ΔT1) obtained by subtracting the radio wave arrival times received by each of the plurality of in-vehicle UWB radio waves by a predetermined combination of the UWB radio waves transmitted by the mobile UWB radio wave, and the mobile phone UWB is calculated. The second radio wave arrival direction is calculated from the time (ΔT2) obtained by the difference between the radio wave arrival times received by the plurality of in-vehicle UWB radio waves by different combinations of the UWB radio waves transmitted by the radio waves, and the first radio wave arrival direction is calculated. A vehicle communication device including a control unit (3, 21) that identifies the position of the portable device based on the intersection of the second radio wave arrival direction and the second radio wave arrival direction. The portable device is a smartphone,
The in-vehicle trigger radio and the portable trigger radio are both BLE radios that communicate by Bluetooth Low Energy (hereinafter referred to as "BLE"), and BLE is used as a trigger signal. The vehicle communication device according to 1. Based on the position information of the portable device specified by the intersection of a plurality of radio wave arrival directions, the control unit either has the portable device on the driver's seat side of the vehicle or the portable device on the passenger seat side of the vehicle. The vehicle communication device according to claim 1 or 2, wherein it is determined whether or not the portable device is present on the rear side of the vehicle. The plurality of in-vehicle UWB radios are configured to include a first station (2a), a second station (2b), and a third station (2c).
Information regarding the distance between the first station and the second station is stored in advance in the control unit.
The third station transmits UWB radio waves and
The first station and the second station each receive the UWB radio waves transmitted by the third station, and receive the UWB radio waves.
The control unit has a value obtained by multiplying the time difference between the arrival times of UWB radio waves received by the first station and the second station by the propagation speed of the radio wave, and the first stored in advance. The vehicle according to any one of claims 1 to 3, wherein a correction value for calculating the position of the portable device is calculated from the ratio of the distance between the station and the second station. Communication device. The plurality of in-vehicle UWB radios are configured to include a first station, a second station, and a third station.
At least the second station has an integrated circuit (hereinafter referred to as "IC") and an internal clock, and the IC has information regarding the distance between the first station and the second station in advance. Remembered,
The third station transmits UWB radio waves and
When the first station receives the UWB radio wave transmitted by the third station, the first station transmits the UWB radio wave, and the first station transmits the UWB radio wave.
The second station receives the UWB radio wave transmitted by the third station and the UWB radio wave transmitted by the first station, respectively.
The IC possessed by the second station stores in advance the time obtained by the difference between the arrival time of the radio wave receiving the UWB radio wave transmitted by the third station and the arrival time of the radio wave receiving the UWB radio wave transmitted by the first station. Claims 1 to 1 to calculate the relay processing time from the reception of the UWB radio wave to the transmission of the UWB radio wave by the first station based on the distance between the first station and the second station. The vehicle communication device according to any one of 3. When the plurality of in-vehicle UWB radios (2a, 2c) receive the UWB radio waves transmitted by the portable UWB radios, they transmit the UWB radio waves.
Among the plurality of in-vehicle UWB radios, the in-vehicle UWB radio (2b) having the IC and the internal clock is transmitted from the UWB radio wave transmitted by the portable UWB radio and from the other in-vehicle UWB radio. Receives UWB radio waves and
The IC included in the in-vehicle UWB radio is configured to function as a control unit that calculates a first radio wave arrival direction and a second radio wave arrival direction and identifies the position of the portable device. Item 5. The vehicle communication device according to Item 5. The plurality of in-vehicle UWB radios are configured to include a reference station (2d) and a sub station (2e).
The reference station and the sub station have an IC (21) and an internal clock (22), respectively.
The distance between the reference station and the sub station is measured by bidirectional communication, and the distance is measured.
The distance between the reference station and the sub station is measured by unidirectional communication, and
A claim that calculates and corrects a time error between the internal clock of the reference station and the internal clock of the sub-station based on the difference between the distance measured by two-way communication and the distance measured by unidirectional communication. The vehicle communication device according to any one of 1 to 3. The calculation of the distance between the reference station and the sub station by two-way communication is
The reference station transmits UWB radio waves, stores the transmission time of the UWB radio waves, and
The sub-station that has received the UWB radio wave transmitted by the reference station transmits the UWB radio wave by adding the relay processing time data from the reception of the UWB radio wave to the transmission of the UWB radio wave.
The reference station that has received the UWB radio wave transmitted by the sub station stores the arrival time of the UWB radio wave and the relay processing time data added to the UWB radio wave.
The reference station and the sub station are based on the time obtained by subtracting the relay processing time data from the time from the transmission time when the reference station transmits the UWB radio wave to the arrival time of the radio wave received by the reference station for the UWB radio wave transmitted by the sub station. It calculates the distance to
On the other hand, the calculation of the distance between the reference station and the sub station by unidirectional communication is
The reference station adds transmission time data and transmits UWB radio waves.
The sub-station that has received the UWB radio wave transmitted by the reference station stores the arrival time of the radio wave that received the UWB radio wave and the transmission time data added to the UWB radio wave.
According to claim 7, the distance between the reference station and the sub station is calculated based on the time from the transmission time when the reference station transmits the UWB radio wave to the arrival time of the radio wave received by the sub station. The vehicle communication device described. The in-vehicle UWB radio, which is the reference station, is provided at a place where communication is possible with the plurality of in-vehicle UWB radios, which are the sub-stations, among the plurality of in-vehicle UWB radios. The vehicle communication device according to 7 or 8.

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