Vehicle position identification system and vehicle position identification method

Abstract

To provide a vehicle position identification system and a vehicle position identification method capable of accurately and promptly identifying a position of a vehicle without using radio waves of a GPS.SOLUTION: A vehicle position identification system comprises: first devices 1 which are attached to a plurality of objects (e.g., electric poles 6) whose position information can be identified or first devices 1 which are attached to a plurality of arbitrary locations and can acquire the own position information; a second device 2 which is mounted on or annexed to a vehicle 5; distance calculation means which calculates a distance between each of the plurality of first devices 1 and the second device 2 on the basis of a propagation time of information or signals exchanged between each of the plurality of first devices 1 and the second device 2; and position identification means which identifies a position of the vehicle 5 to which the second device 2 is mounted, on the basis of the distance between each of the plurality of first devices 1 and the second device 2 calculated by the distance calculation means and the position information of the objects to which the first devices 1 are attached or the own position information acquired by the first devices 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle location determination system and a vehicle location determination method that can be used to determine the current location of a vehicle, and in particular to a technology that can accurately obtain the current location of a vehicle without delay without using GPS radio waves. [Background technology]

[0002] Car navigation systems that display the vehicle's current location and provide route guidance to a destination are becoming widespread. A typical car navigation system has a GPS function and uses a terminal installed in the vehicle to receive signals sent from GPS satellites (signals that contain time data obtained from atomic clocks installed on the satellites, as well as information on the positions and orbits of celestial bodies) to determine the vehicle's location. In other words, the system measures the time it takes for radio waves emitted from the satellite to reach the terminal, determines the distance between the satellite and the terminal, and performs this process with four or more satellites to determine the vehicle's current location.

[0003] However, relying solely on GPS functionality can result in errors in the radio waves emitted from satellites due to weather and other factors, which can lead to discrepancies in the measurement of your current location. Furthermore, radio waves from satellites may not be received properly under elevated roads or at intersections with multiple levels. Furthermore, near high-rise buildings or in mountainous areas, there is the inconvenience of communication problems known as "multipath," where satellite signals are reflected by buildings or mountains. For this reason, car navigation systems often use autonomous navigation based on information from acceleration sensors and gyros in the car navigation system, as well as vehicle speed signals generated by tire rotation, in case signals from satellites cannot be received properly (see Non-Patent Document 1, etc.). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "How does a car navigation system determine your current location? How GPS works", [online], Gazoo, [Retrieved January 25, 2024], Internet<URL: https: / / gazoo.com / column / daily / 20 / 01 / 11 / > Summary of the Invention [Problem to be solved by the invention]

[0005] However, the position detection accuracy of GPS receivers used in car navigation systems is only a few meters, which is not necessarily high. Also, there is a delay in displaying the current location on the screen depending on the communication status with satellites located far away. Furthermore, while receiving signals from multiple satellites ensures a reasonable degree of accuracy in terms of direction, the accuracy in terms of height is insufficient.

[0006] For this reason, at complex intersections where many roads intersect, such as that shown in Figure 11(a), there is a concern that drivers may make the wrong turn, and at complex junctions where many roads intersect at different levels, such as that shown in Figure 11(b), there is a concern that drivers may not know which road they are traveling on, or which road they should take.

[0007] To solve this problem, it is possible to improve the accuracy of the GPS receiver or to add an altimeter to take altitude information into account when determining location information, but this has the disadvantage of making the system expensive and large-scale.

[0008] The present invention has been made in consideration of the above circumstances, and its main objective is to provide a vehicle position determination system and a vehicle position determination method that are capable of instantly obtaining highly accurate position information, even in locations where the reception sensitivity of GPS radio waves is poor, without requiring a device with high position detection accuracy or a large-scale device. [Means for solving the problem]

[0009] In order to achieve the above object, a vehicle location identification system according to the present invention comprises: A vehicle location identification system that identifies the location of a vehicle using a first device attached to a plurality of objects whose location information can be identified and a second device attached to or associated with the vehicle, distance calculation means for calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a position specifying means for specifying the position of the vehicle to which the second device is attached or attached, based on the distances between each of the plurality of first devices and the second device calculated by the distance calculating means, and position information of the object to which the first device is attached, or position information of the portion of the object to which the first device is attached; and It is characterized by having:

[0010] Here, "attached" to the second device is not limited to being directly attached to the interior or exterior surface of the vehicle, but also includes being attached to an object installed inside the vehicle or being embedded in the vehicle body. Also, "attaching" the second device to the vehicle body includes being in a state where the second device moves with the vehicle body even if it is not attached to the vehicle body, such as being placed in a bag or on the dashboard in the vehicle.

[0011] Furthermore, the multiple objects whose location information can be identified (objects to which the first device can be attached) may be objects whose location information is managed in a database, such as utility poles, steel towers, structures such as roadside equipment, and buildings such as houses, offices, and buildings. In particular, in areas with few buildings, structures and buildings such as utility poles and steel towers may be used as targets for attaching the first device. Also, in areas with few utility poles or areas where utility poles are becoming less common, structures such as roadside equipment and buildings may be used as targets for attaching the first device, and these may be selected appropriately depending on the search area. Furthermore, the objects whose location information can be identified (objects to which the first device can be attached) may be mobile objects (other vehicles, aircraft, ships, etc.) that can acquire their own location information.

[0012] Furthermore, the location information of the object on which the first device is attached or the location where the first device is attached is preferably three-dimensional location information that adds height information (ellipsoid height, altitude, etc.) to two-dimensional location information specified by latitude and longitude coordinates, etc. Even when the first device is attached to a utility pole, building, etc., the height of the installation location of the utility pole or building varies depending on the location, and the height from the ground of the first device attached to the utility pole or building also varies, so by managing the height position of the first device, it becomes possible to more accurately specify the location information (three-dimensional location information) including the height of the second device.

[0013] For example, by varying the mounting height of the first device for each utility pole or building and managing the mounting height of the first device for each utility pole or building, and using the 3D position information, it becomes possible to grasp the 3D position information of the second device. By acquiring the 3D position information of the second device in this way, it becomes possible to grasp more accurately the position information of vehicles passing through a junction where roads intersect above and below.

[0014] Therefore, the distance calculation means calculates the distance between each of the multiple first devices and the second device attached to or associated with the vehicle, and the position determination means can determine the position of the second device, i.e., the position of the vehicle, based on the distance between each of the multiple first devices and the second device, and the position information of the object to which the first device is attached or the position information of the attachment location of the first device.

[0015] The calculation of the distance between the first device and the second device by the distance calculation means is premised on the first device and the second device being within a distance range where they can transmit and receive information or signals to each other, so if the first device and the second device are too far apart, the distance between them cannot be calculated. However, if the vehicle on which the second device is attached moves and there is a first device that can transmit and receive information or signals to each other, the distance calculation means will calculate the distance between the first device and the second device. Then, if there are four or more first devices for which distance calculation is possible, the position identification means can identify the three-dimensional position of the second device. Therefore, by adjusting the object on which the first device is attached and the installation height to appropriately distribute the first devices, it is possible to reliably capture the position of a displacing second device.

[0016] Therefore, the distance calculation means calculates the distance between each of the first devices attached to multiple objects whose position information can be identified and the second device, and the position identification means identifies the position of the vehicle to which the second device is attached or attached based on the distance calculated by the distance calculation means and the position information of the object to which the first device is attached.Therefore, the position of the vehicle can be identified without receiving GPS radio waves based on the propagation time of information or signals between the second device attached to or attached to the vehicle and the first device installed in the vicinity not far away, and the position information of the object to which the first device is attached, or the position information of the part of the object to which the first device is attached.Therefore, the time required to calculate the vehicle's position can be shortened compared to when GPS radio waves are used, and the accuracy of the vehicle's position can be improved.

[0017] In order to identify the position of the second device, in addition to the distance between each of the multiple first devices and the second device, position information of each of the first devices is required.In the above-mentioned configuration, position information of the object to which the first device is attached or position information of the attachment location of the first device is used, but if the first device has a GPS function or the like and is able to obtain its own three-dimensional position information, that position information may also be used. That is, the vehicle location identification system according to the present invention is a vehicle location identification system that identifies the location of a vehicle by using a first device that is attached to any of a plurality of locations and is capable of acquiring its own location information, and a second device that is attached to or associated with the vehicle, distance calculation means for calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a location identification means for identifying the location of the vehicle to which the second device is attached or attached, based on the distances between each of the plurality of first devices and the second device calculated by the distance calculation means and on the location information of the first device acquired by the first device; It is characterized by having:

[0018] Here, the first device capable of acquiring its own location information is the first device that acquires its own location information (preferably, three-dimensional location information) by equipping the first device with a GPS function, an altitude measurement function, etc. If such a first device is used, the object to which it is attached does not need to be one whose location information can be specified, and it can be attached to any location (such as a roadside or a bush in a park or a stake driven into the ground), making it easier to adjust the placement of the first device.

[0019] Therefore, the distance calculation means calculates the distance between each of the first devices attached to multiple objects whose position information can be determined and the second device, and the position determination means determines the position of the vehicle to which the second device is attached or attached based on the distance calculated by the distance calculation means and the position information of the first device acquired by the first device. That is, the position of the vehicle can be determined based on the propagation time of information or signals between the second device attached to or attached to the vehicle and the first device installed nearby not far away and the position information acquired by the first device without receiving GPS radio waves, thereby shortening the time required to calculate the vehicle position and increasing the accuracy of the vehicle position. That is, the vehicle position can be determined more quickly than when determining the vehicle position by receiving radio waves from GPS satellites, and the accuracy of determining the position can be higher than with GPS.

[0020] Here, the position information is preferably three-dimensional information. In particular, when roads overlap one another, it is difficult for GPS to capture accurate position information of the vehicle. However, with this configuration, it is possible to capture three-dimensional position information of the nearest first device, so it is possible to accurately capture the position of the vehicle even at a junction where roads intersect one another, or in places where GPS radio waves are difficult to reach, such as under an overpass or between high-rise buildings.

[0021] In addition, when calculating the propagation time of information or signals between each of the first devices and the second device, the difference between the time on the clock of the first device when the information or signal is transmitted from the first device and the time on the clock of the second device when the information or signal transmitted from the first device is received by the second device, It is preferable to calculate the propagation time based on the difference between the clock time of the second device when the second device transmits information or a signal and the clock time of the first device when the first device receives the information or a signal transmitted from the second device. By adopting such a method, it becomes possible to calculate the propagation time without considering the time difference between the clock time of the first device and the clock time of the second device. [Effects of the Invention]

[0022] As described above, according to the vehicle position determination system and vehicle position determination method of the present invention, the distance between each of the multiple first devices and the second device is calculated based on the propagation time of information or signals between each of the multiple first devices and the second device, and the position of the vehicle to which the second device is attached or attached is determined based on the calculated distance between each of the multiple first devices and the second device, as well as the position information of the object to which the first device is attached or the position information of the part of the object to which the first device is attached, or the vehicle's own position information obtained by the first device.Therefore, it is possible to instantly obtain highly accurate position information even in places where the reception sensitivity of GPS radio waves is poor (such as under overpasses such as multi-level intersections, in tunnels, indoors, or between high-rise buildings), without the need for expensive and large-scale equipment. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram illustrating an example of the configuration of a vehicle position specifying system according to the present invention. [Figure 2] FIG. 2 is a block diagram showing the configuration of a first device. [Figure 3] FIG. 2 is a block diagram showing the configuration of a second device. [Figure 4] FIG. 2 is a block diagram showing the configuration of a server device. [Figure 5] 10 is a flowchart showing a distance calculation process. [Figure 6] 10 is a flowchart showing a position identification process. [Figure 7] 1 is a diagram showing an example of a display on the screen of a car navigation system showing the vehicle position identified by the vehicle position identifying system according to the present invention. FIG. [Figure 8] 10 is a diagram illustrating a transition of combinations that allow distance calculation between a first device and a second device mounted on a vehicle. FIG. [Figure 9] 10 is a diagram illustrating the transition of combinations that allow distance calculation between a first device attached to a fixed object such as a utility pole or a vehicle and a second device mounted on the vehicle. FIG. [Figure 10] FIG. 10 is a block diagram showing another example of the configuration of the first device. [Figure 11] 1A is a diagram showing an example of a complex intersection where many roads intersect, and FIG. 1B is a diagram showing an example of a complex junction where many roads intersect at different levels. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0025] 1, a vehicle location identification system S includes a plurality of first devices 1 and a second device 2 attached to or associated with a vehicle 5. The vehicle location identification system S may also include a server device 3.

[0026] The first device 1 and the second device 2 can be directly connected for communication. The first device 1 can also be connected to a server device 3 via a communication network 4, and the second device 2 can also be connected to the server device 3 via the communication network 4.

[0027] The first device 1 can be used as a reference device for synchronizing the clock of the second device 2, but in this system, it is not necessarily necessary to synchronize the clock of the first device 1 with the clock of the second device 2. Therefore, in the following example, we will explain the case where the distance between the first device 1 and the second device 2 is calculated and the position of the second device 2 is determined without synchronizing the clock of the first device 1 with the clock of the second device 2, assuming that there is a time discrepancy (time difference) between the clock of the first device 1 and the clock of the second device 2.

[0028] Furthermore, the first device 1 can function as the first device 1 with respect to multiple second devices 2, and when multiple second devices 2 exist, each of these multiple second devices 2 can function as the first device with respect to multiple other second devices. In other words, if the position of a second device can be identified, the distance between that second device and the other second devices can be calculated, and this can be used to identify the positions of the other second devices.

[0029] As shown in FIG. 2, the first device 1 includes a control unit 11, an RF chip 12, and an oscillator 13.

[0030] The control unit 11 is composed of a CPU and a ROM, and executes a program stored in the ROM to control the first device 1. The RF chip 12 is equipped with at least a clock 14, but may also be equipped with a phase detector. The RF chip 12 also has a function for processing the transmission and reception of wireless signals, and the data received by the RF chip 12 is subjected to arithmetic processing by the control unit 11.

[0031] Oscillator 13 oscillates at a predetermined frequency and outputs a signal that provides operational timing for each component of the device. A crystal oscillator or an atomic oscillator can be used as oscillator 13. Clock 14 uses the output signal from oscillator 13 as a source of oscillation to clock and output the time. The time clocked by clock 14 is controlled by control unit 11 to be transmitted to second device 2 via RF chip 12. If a phase detector is further provided, it detects the phase of the carrier wave constituting the information received from second device 2 and also detects the phase of the signal transmitted by oscillator 13 of first device 1.

[0032] In the present vehicle position identification system S, the installation location of the first device 1 is not particularly limited, but it is preferable that the first device 1 be installed in a structure, building, or structure from which position information can be identified. In particular, since the first device 1 is used to identify the current position of a vehicle traveling on a road, it is preferable that the first device 1 be installed in a location with good visibility from the roadway with no obstructions between it and the vehicle.

[0033] For example, in areas with few buildings or insufficient infrastructure, the system can be applied to a wide area by attaching it to an upright structure such as a utility pole 6 or steel tower that supports overhead power lines. Utility poles 6 and steel towers are scattered over a wide area at predetermined intervals, and various information including their location information is managed in a database, making it easy to identify the location information, and also enabling the first device 1 to be installed in a high place where the signal can easily reach long distances. On the other hand, in areas where there are few utility poles or where utility poles are becoming less common, the devices may be attached to buildings 7 such as roadside buildings, or streetlights 8 or signboards 9 installed on the side of or on the road. In this way, the target to which the first device 1 is attached may be appropriately selected depending on the infrastructure situation in the area where the vehicle location identification system S is used. In this embodiment, for the sake of convenience, the first device 1 is described as being attached to a utility pole 6.

[0034] The object to which the first device 1 is attached must have identifiable position information, but the position information of the object may be stored in a database in advance or may be measured and acquired later as needed. Also, if only two-dimensional position information is available, it is advisable to prepare three-dimensional position information that includes information on the height at which the first device 1 is installed.

[0035] In order to obtain three-dimensional position information of a vehicle, the first devices 1 do not need to be installed on the same plane, and it is preferable that adjacent first devices 1 are installed at different heights. For example, even when the first devices 1 are attached to utility poles, it is preferable to vary the attachment height of the first devices for each utility pole, manage the attachment height of the first devices 1 together with the position information of the utility pole for each utility pole, and use this as position information (three-dimensional position information) of the attachment location of the first devices 1.

[0036] Furthermore, it is desirable that the first device 1 be installed comprehensively around the roadway, but installing it in areas where there are few intersections or overpasses and where GPS radio waves are easily received is not cost-effective, so it is particularly advisable to place the first device 1 mainly in areas where GPS radio waves are difficult to reach, such as under elevated roads, in mountainous areas, between high-rise buildings, around intersections where many roads intersect, and around overpasses where roads overlap above and below.

[0037] In addition, the location information of the installation location of the first device 1 may be stored in a server device 3 or the like in association with identification information that can identify the first device 1, or may be available from another management server that manages the location information via the communication network 4.

[0038] Next, the second device 2 will be described. This second device 2 is attached to or attached to the vehicle 5. The second device 2 may be attached to or attached to the vehicle before the vehicle is driven, or may be attached to or attached to the vehicle only when it is desired to obtain vehicle location information using the vehicle location identification system S. In other words, if the second device 2 is operated or stopped by turning its own power on and off, the second device 2 may be turned on and operated (functioning) only when it is desired to obtain vehicle location information.

[0039] Here, the vehicle 5 is not particularly limited, and may be any vehicle that can travel on a roadway, including automobiles, motorcycles, bicycles, trailers, military vehicles, etc. The term "attachable" for the second device 2 does not only mean that the second device 2 is directly attached to the vehicle by some kind of attachment means, but also that the second device 2 is fixed to something that houses the vehicle (for example, a container) or something attached to it (for example, a luggage rack attached to the roof of the vehicle). Also, the second device 2 may be fixed to the outside of the vehicle 5 by a string, band, wire, chain, adhesive, or the like, or may be embedded in the body of the vehicle.

[0040] Furthermore, being able to attach the second device 2 means that even if the second device 2 is not attached to the vehicle, it can be moved along with the vehicle, and for example, if there is a bag or storage case in the vehicle compartment, it can be placed in that bag or storage case.

[0041] 3, the second device 2 includes a control unit 21, an RF chip 22, and an oscillator 23, all of which are connected via a bus. The second device 2 also includes a RAM 24 and a storage unit 25, all of which are connected to the control unit 21 via a bus.

[0042] The RF chip 22 includes at least a clock 26 and may optionally include a phase detector.

[0043] The control unit 21 is configured with a CPU and a ROM, and executes programs stored in the storage unit 25 to control the second device 2. The RAM 24 is a work area for the control unit 21, and the storage unit 25 is a memory area for saving programs and data. The control unit 21 performs arithmetic processing based on the programs and data read from the RAM 24 and the storage unit 25, as well as data input from an input unit (not shown).

[0044] The RF chip 22 is capable of transmitting and receiving data to and from other computer devices. Data received by the RF chip 22 is loaded into the RAM 24 and is then subjected to arithmetic processing by the control unit 21.

[0045] Oscillator 23 oscillates at a predetermined frequency and outputs a signal that provides operational timing for each component of the device. Oscillator 23 can be a crystal oscillator or an atomic oscillator. Clock 26 uses the output signal from oscillator 23 as a source of oscillation to clock and output the time. The time clocked by the clock is controlled by control unit 21 to be transmitted to first device 1 via RF chip 22. If a phase detector is provided, it detects the phase of the carrier wave constituting the information received from first device 1 and also detects the phase of the signal oscillated by oscillator 23 of second device 2.

[0046] Next, the server device 3 of the present invention will be described. The server device 3 can acquire location information from the second device 2.

[0047] The acquired location information is stored as location information of the vehicle 5 (second device 2) in the server device 3. The location information of the vehicle 5 (second device 2) is transmitted to the server device 3, for example, from the second device 2 in association with identification information capable of identifying the second device 2 and the time when the location information was identified. Note that the server device 3 may enable communication between the first device 1 and the second device 2 via a smart meter installed in a building or the like.

[0048] 4 is a block diagram showing the configuration of a server device 3 according to an embodiment of the present invention. The server device 3 includes at least a control unit 31, a RAM 32, a storage unit 33, and a communication interface 34, which are connected to each other via an internal bus.

[0049] The control unit 31 is composed of a CPU, a ROM, etc., and executes programs stored in the storage unit 33 to control the server device 3. The control unit 31 also has an internal timer that measures time. The RAM 32 is the work area of ​​the control unit 31. The storage unit 33 is a memory area for saving programs and data. The control unit 31 reads out the programs and data from the storage unit 33 or the RAM 32, and performs program execution processing based on information received from the first device 1 or the second device 2, etc.

[0050] (Distance calculation process) Next, a process for calculating the distance between the first device 1 and the second device 2 using the above configuration will be described.

[0051] This distance calculation process is a process that calculates the distance between each first device 1 and the second device 2 based on the propagation time Tp of the information or signal between each first device 1 and the second device 2 when the first device 1 and the second device 2 are within a distance range in which they can send and receive information or signals to each other.

[0052] The distance calculation process is executed at predetermined time intervals (for example, every minute) or whenever a predetermined condition is met, and involves steps S1 to S16 as shown in Fig. 5. For convenience, the case where the distance between one first device 1 and one second device 2 is calculated will be described here.

[0053] First, information or a signal is transmitted from the first device 1 to the second device 2 (step S1). The information or signal transmitted from the first device 1 to the second device 2 is not particularly limited.

[0054] The first device 1 clocks the time (T11) when the information or signal is transmitted in step S1 (step S2), and stores this clocked time in the memory in the control unit 11 (step S3).

[0055] Thereafter, in response to this, second device 2 receives the information or signal from first device 1 (step S4). Second device 2 clocks the time (T21) at which the information or signal was received in step S4 (step S5). Then, the clocked time (including the measured phase if the phase is measured) is stored in memory or storage unit 25 within control unit 21 (step S6).

[0056] Next, second device 2 transmits information or a signal to first device 1 (step S7). There are no particular limitations on the information or signal transmitted from second device 2 to first device 1. Second device 2 clocks the time (T22) at which the information or signal was transmitted in step S7 (step S8). The clocked time is then stored in memory or storage unit 25 within control unit 21 (step S9).

[0057] First device 1 receives the information or signal transmitted in step S7 (step S10). First device 1 clocks the time (T12) at which the information or signal was received in step S10 (step S11). Then, the clocked time (including the measured phase if the phase is measured) is stored in the memory of control unit 11 (step S12).

[0058] Thereafter, the first device 1 transmits to the second device 2 via the RF chip 12 of the first device 1 (step S13) the information about the time (T11) when the signal was transmitted in step S1, which was stored in step S3, and the information about the time (T12) when the signal was received in step S10, which was stored in step S12. At this time, if the first device 1 has recorded location information of the utility pole 6 to which it is attached, it transmits this information together with the location information to the second device 2.

[0059] Then, the second device 2 receives information regarding the time (T11) when the first device 1 transmitted the information or signal in step S1, and information regarding the time (T12) when the first device received the information or signal in step S10 (step S14).

[0060] Next, the second device 2 calculates the distance between the first device 1 and the second device 2 (step S15). This calculation of the distance is performed as follows.

[0061] After transmitting information regarding the clock time (T11) of the first device to the second device 2 via radio waves, the difference between this and the clock time (T21) of the second device 2 when this information is received by the second device 2 is recorded on the second device side as ΔTa. That is, if the clock time of the first device when information or a signal is transmitted from the first device 1 to the second device 2 is defined as T11, and the clock time of the second device when the second device 2 receives and clocks the information or signal transmitted from the first device 1 is defined as T21, and the difference between these is ΔTa, this ΔTa is the difference between the time between the clocks of the first device 1 and the second device 2 (time difference: T20-T10) plus the propagation delay (propagation time) Tp, resulting in the relationship shown in Equation 1. This time difference (T20-T10) will be zero if the clocks of the first device and the second device are synchronized, but here we assume that a time difference (T20-T10) exists (they are not synchronized). [Formula 1]ΔTa=T21-T11=(T20-T10)+Tp

[0062] In order to find this propagation time Tp, the second device 2 also sends information about the time on its clock (T22) to the first device 1, and the difference between this and the time on the clock of the first device 1 (T12) when it is received by the first device 1 is recorded as ΔTb on the first device side. In other words, if the time on the clock of the second device when information or a signal is transmitted from the second device 2 to the first device 1 is defined as T22, and the time on the clock of the first device 1 when the information or signal transmitted from the second device 2 is received and clocked by the first device 1 is defined as T12, and the difference between these is defined as ΔTb, this ΔTb is the difference between the time on the clock of the first device 1 and the time on the clock of the second device 2 (time difference: T10-T20) plus the propagation delay (propagation time) Tp, resulting in the relationship shown in Equation 2. Here too, the time difference (T10-T20) will be zero if the clocks of the first device 1 and the second device 2 are synchronized, but here we assume that a time difference (T10-T20) exists (they are not synchronized). [Formula 2]ΔTb=T12−T22=(T10−T20)+Tp

[0063] If the time difference between the clocks (T20-T10) and (T10-T20) is added when transmitting from the first device to the second device, then the same amount of time difference will be subtracted when transmitting from the second device to the first device. Therefore, when equations 1 and 2 are added together to find the propagation time Tp, the terms for the time differences (T20-T10) and (T10-T20) cancel out, resulting in the relationship given by equation 3. [Formula 3] Tp=(ΔTa+ΔTb) / 2 =((T21-T11)+(T12-T22)) / 2

[0064] Incidentally, the time difference (T10-T20) is expressed by the relationship in Equation 4, calculated by subtracting Equation 1 from Equation 2. [Formula 4](T10-T20)=(ΔTa−ΔTb) / 2

[0065] Therefore, the propagation time Tp can be calculated based only on the time read by the clock of the first device 1 and the time read by the clock of the second device 2.

[0066] Then, the propagation time calculated by Equation 3 is multiplied by the propagation speed (for example, high speed) of the information or signal to calculate the separation distance between the first device 1 and the second device 2.

[0067] Then, the distance between the first device 1 and the second device 2 calculated in step S15 is stored in the memory in the control unit 21 or in the storage unit 25 (step S16). By executing step S16, the distance calculation process is completed.

[0068] Therefore, since equation (3) for calculating the propagation time Tp does not include a term for the time difference (time difference: T20-T10) between the clock of the first device 1 and the clock of the second device 2, the propagation time for information or signals to propagate between the first device 1 and the second device 2 can be calculated regardless of whether there is a time difference between the clock of the first device 1 and the clock of the second device 2 (independent of the time difference (time difference: T10-T20) between the clock of the first device 1 and the clock of the second device 2).

[0069] The above distance calculation process can be performed between all first devices 1 within a distance range where information or signals can be transmitted and received between the second device 2 and the first device 1. Therefore, if the second device 2 (vehicle 5) moves and its position changes from moment to moment, the distance calculation process is performed only between the first device 1 and the second device 2 within a distance range where information or signals can be transmitted and received at the time the process is started. Therefore, the first devices for which the distance to the second device 2 is calculated will change over time.

[0070] In the above, since it is possible to calculate the distance between the first device 1 and the second device 2 even if there is a time difference between the clock of the first device 1 and the clock of the second device 2, there is no need to deliberately synchronize the clock of the first device 1 and the clock of the second device 2. However, it is also possible to correct the time on the first device 1 or the second device 2 based on the time difference calculated using Equation 4 (synchronizing the time on the clock of the first device 1 and the time on the clock of the second device 2), and then calculate the propagation time to calculate the distance.

[0071] [Location identification process] Next, a process for identifying the position of the vehicle 5 equipped with the second device 2 will be described. This position identification process is a process for identifying the position of the second device 2 based on the distances between each of the multiple first devices 1 and the second device 2 calculated in the distance calculation process. Since the second device 2 is provided in the vehicle 5, this can be said to be a process for identifying the position of the vehicle 5.

[0072] This position determination process is preferably performed immediately after the distance calculation process is completed. In order to determine the position of the second device 2, it is necessary that the distance calculation device has calculated the distances between one second device 2 and each of the multiple first devices 1.

[0073] In other words, when obtaining three-dimensional position information of a vehicle (obtaining x, y, z coordinates), it is possible to identify the position of the second device 2 based on the distance between one second device 2 and at least four first devices 1 and the position information of each of the four first devices 1 used to calculate this distance. Therefore, this system can identify the three-dimensional position of the second device 2 if it can obtain four or more pieces of distance data between the first device 1 and the second device 2. Therefore, it is advisable to appropriately distribute the first devices 1 so that the second device 2 can send and receive information or signals to at least four first devices 1 even if the second device 2 moves. In particular, near intersections where positional accuracy is required or at junctions where roads intersect above and below, the number and three-dimensional positions of the first devices 1 must be adjusted in advance to obtain the required accuracy.

[0074] 6 shows a flowchart of a location specification process according to an embodiment of the present invention. This location specification process can be executed by any of the first device 1, the second device 2, or the server device 3. When the location specification process is executed by the first device 1 or the server device 3, the distance between each of the multiple first devices 1 and the second device 2 and the location information of the first device 1 can be associated with the identification information of the second device 2 and transmitted to the first device 1 or the server device 3 for use.

[0075] First, in order to perform the position identification process, distance data for at least four different first devices 1 and second devices 2 must be acquired at the same or similar times. Here, "similar times" refers to times within a predetermined time range from time 1. This is because if the distance data are not calculated at the same or similar times (for example, calculated when the propagation times of information or signals between each of the multiple first devices 1 and the second device 2 are measured at the same or similar times), it becomes difficult to accurately identify the location of the second device 2, assuming that it is moving.

[0076] First, it is determined whether or not four or more pieces of data on the distance between the first device 1 and the second device 2 have been acquired within a predetermined time range (step S21).

[0077] If four or more pieces of data on the distance between the first device 1 and the second device 2 are not acquired within a specified time range, accurate three-dimensional position information cannot be obtained even with this positioning method using wireless two-way time transfer, so positioning control using GPS is performed as usual (step S22).At that time, if GPS radio waves are difficult to receive or cannot be received, self-contained navigation using information from the acceleration sensor and gyro in the car navigation system and vehicle speed signals accompanying tire rotation is also used as necessary. If the current position of the second device (vehicle) can be identified by GPS or autonomous navigation, the current position is identified (step S23), and processing such as displaying the position on a map is performed (step S24).

[0078] On the other hand, if four or more pieces of data on the distance between first device 1 and second device 2 are acquired within a predetermined time range, the present position determination method using wireless two-way time transfer can be used to obtain accurate three-dimensional position information, and so the method is switched to the position determination method using wireless two-way time transfer described above (step S25). The current position of the vehicle (second device 2) is then determined using the wireless two-way time transfer method (step S23), and display processing, such as displaying the current position of the vehicle on the display screen of the car navigation system, is performed (step S24). In particular, since accurate three-dimensional position information of the vehicle is obtained, the current position of the vehicle can be displayed on a two-dimensional road display (left side) and a three-dimensional road display (right side), as shown in FIG. 7, allowing the vehicle to visualize the current position in three dimensions. This makes it possible to accurately grasp the road the vehicle is traveling on and the conditions of the destination at a junction where multiple roads intersect vertically. The display process in step S24 ends the position identification process.

[0079] Therefore, if there are four or more first devices 1 that can send and receive information or signals with second devices 2 attached to or attached to a vehicle 5 within a specified time range, the three-dimensional position of the second device 2 is determined by a position determination process based on the distance between each first device 1 and second device 2 calculated by the distance calculation process at the same or similar time, and the position information of the object on which each first device 1 is attached (position information of a utility pole, etc.) used in this distance calculation, or the position information of the installation location of the first device 1, i.e., the position information of the object on which the first device 1 is attached plus the height information at which the first device 1 is attached.Therefore, for example, as shown in Figure 8, if a vehicle 5 attached with a second device 2 moves from the position shown in (a) where distances can be calculated with four first devices 1 to the position shown in (b), it becomes possible to continuously determine the position of the second device 2, which changes over time. In this case, the position information of the first device uses three-dimensional position information that includes height information (ellipsoid height, altitude, etc.), so it is possible to accurately identify the three-dimensional position of the second device 2.

[0080] Furthermore, since the system calculates distance and obtains location information by transmitting and receiving information or signals over a short distance between the first device and the first device without using GPS radio waves, the time required to calculate the vehicle's location information (the time required to display the vehicle's current location on the navigation system screen) can be shortened, and the positioning accuracy can be improved compared to using GPS signals. Therefore, at a complex intersection where multiple roads intersect, such as shown in Figure 11(a), the current location information is displayed without delay, making it possible to obtain appropriate information on which section and which turn to take. Furthermore, even when traveling on overlapping roads, such as shown in Figure 11(b), it is possible to accurately determine which road the vehicle is traveling on or which road to take.

[0081] In the above example, the first device 1 is installed on a permanently installed fixed object such as a structure or construction (such as a utility pole, tower, or building) as an object whose location information can be identified. However, the first device 1 may also be installed on a moving object, not limited to a fixed object, as long as the location information can be identified.

[0082] For example, many vehicles are equipped with navigation systems, and many of them can determine their own vehicle position using GPS or the like. Furthermore, altitude positioning using GPS has become possible to some extent. Therefore, as shown in FIG. 9 , if a first device 1 is attached to a specific vehicle (e.g., a construction vehicle or a patrol vehicle) and this is designated as a reference vehicle 10, and if information or signals can be transmitted and received between the first device 1 and the reference vehicle 5 and the second device 2 attached to the vehicle 5, the distance between the reference vehicle 10 and the vehicle 5 can be calculated. If a total of four or more distances can be calculated, including the distance to the first device 1 attached to a nearby object, the three-dimensional position of the vehicle can be determined.

[0083] In the above, the reference vehicle 10 has been given as an example of a moving body whose position information can be identified, but the moving body is not limited to this and may be a ship, a train, a drone (aerial drone, water drone), or the like.

[0084] With this configuration, the installation area of ​​the first device 1 is not fixed (the installation area can be changed), so it is possible to selectively select areas with heavy traffic or areas where congestion occurs, and provide accurate location information.

[0085] Furthermore, in the above configuration, an example has been described in which the first device 1 is attached to an object whose position information can be identified, but the reason why the first device 1 is attached to an object whose position information can be identified is because the position information of the first device 1 is required to identify the position of the second device 2.

[0086] Therefore, as long as the first device 1 can acquire its own location information, the object to which the first device 1 is attached may not be one whose location information can be determined, and the first device 1 can be installed at any location. In other words, it is possible to identify the location of the vehicle 5 by using the first device 1 that is attached to any multiple locations (four or more) and can acquire its own location information, and the second device 2 that is mounted on the vehicle.

[0087] Fig. 10 shows an example of the configuration of a first device 1 capable of acquiring its own location information. Similar to Fig. 2, this first device 1 includes a control unit 11, an RF chip 12, and an oscillator 13, and also includes a GPS receiver 15 and, if necessary, an altimeter 16, so that it can acquire its own three-dimensional location information by receiving signals from GPS satellites and detecting its own altitude.

[0088] The other configurations are the same as those of the first device 1 shown in FIG. 2, so the same parts are denoted by the same reference numerals and the description thereof will be omitted.

[0089] By using such a first device 1, three-dimensional position information of the first device 1 can be obtained regardless of where the first device 1 is installed, so if the distance between each of multiple (four or more) first devices 1 and the second device 2 is calculated using a distance calculation means, it becomes possible to determine the three-dimensional position of the vehicle 5 on which the second device 2 is attached based on the calculated distances and the position information of the first device 1 itself obtained by the first device 1. [Explanation of symbols]

[0090] 1 1st device 2 Second device 5 vehicles 6. Electric pole S Vehicle location system

Claims

1. A vehicle location identification system that identifies a location of a vehicle using a first device attached to a plurality of objects whose location information can be identified and a second device attached to or associated with the vehicle, a distance calculation means for calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a position specifying means for specifying the position of the vehicle to which the second device is attached or associated, based on the distances between each of the plurality of first devices and the second device calculated by the distance calculating means, and position information of an object to which the first device is attached, or position information of a portion of the object to which the first device is attached; and A vehicle location identification system comprising:

2. A vehicle location identification system that identifies the location of a vehicle using a first device that is attached to any of a plurality of locations and can acquire its own location information, and a second device that is attached to or associated with the vehicle, distance calculation means for calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a location identification means for identifying the location of the vehicle to which the second device is attached or attached, based on the distances between each of the plurality of first devices and the second device calculated by the distance calculation means and on the location information of the first device acquired by the first device; A vehicle location identification system comprising:

3. 3. The vehicle position determining system according to claim 1, wherein the position information of the first device and the position of the vehicle determined by the position determining means are three-dimensional positions.

4. 3. The vehicle position specifying system according to claim 1, wherein each of the first devices is provided at a different height.

5. The difference between the time on the clock of the first device when the first device transmits information or a signal and the time on the clock of the second device when the second device receives the information or signal transmitted from the first device; The difference between the time on the clock of the second device when the second device transmits information or a signal and the time on the clock of the first device when the first device receives the information or signal transmitted from the second device.

2. The vehicle position specifying system according to claim 1, wherein the propagation time is calculated based on the following:

6. A vehicle location determination method for determining a location of a vehicle using a first device attached to a plurality of objects whose location information can be determined, and a second device attached to or associated with the vehicle, comprising: a distance calculation step of calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a position specifying step of specifying the position of the vehicle on which the second device is mounted, based on the distances between each of the plurality of first devices and the second device calculated in the distance calculation step, and position information of an object on which the first device is mounted, or position information of a portion of the object on which the first device is mounted; A vehicle position determination method comprising:

7. A vehicle location determination method for determining the location of a vehicle using a first device attached to any of a plurality of locations and capable of acquiring its own location information, and a second device attached to or associated with the vehicle, comprising: a distance calculation step of calculating a distance between each of the plurality of first devices and the second device based on a propagation time of information or a signal between each of the plurality of first devices and the second device; a location determination step of determining the location of the vehicle on which the second device is mounted, based on the distances between each of the plurality of first devices and the second device calculated in the distance calculation step and on the location information of the first device acquired by the first device; A vehicle position determination method comprising:

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