Positioning device, positioning method, and positioning program

Abstract

The objective is to provide a positioning device, a positioning method, and a positioning program that can accurately determine the relative position between a vehicle and a roadside unit with a simple configuration and a simple processing procedure when a vehicle passes a roadside unit. [Solution] The route difference measurement unit 20 measures the route difference from the roadside unit to each antenna based on the difference in arrival time when each antenna 14 receives the transmission signal transmitted from the roadside unit. The relative position calculation unit 22 calculates the change in the relative position of each antenna 14 due to the movement of the vehicle during the time interval in which the route difference is measured. The positioning calculation unit 24 calculates the position of the roadside unit based on the route difference measured at at least two different vehicle positions and the relative position of the vehicle between those different positions.

Description

[Technical Field]

[0001] The present invention relates to a positioning device, a positioning method, and a positioning program. [Background Art]

[0002] Various methods for positioning using communication between roadside units of road-to-vehicle communication and vehicles have been studied as disclosed in Patent Documents 1 to 3 and Non-Patent Document 1.

[0003] Patent Document 1 discloses a communication system in which three antennas of a roadside unit are installed spaced apart around a positioning area, the time difference of arrival when a transmission signal from an on-board unit is received by the three antennas of the roadside unit is obtained, and hyperbolic positioning is performed from the time difference of arrival to specify the vehicle position.

[0004] Patent Document 2 discloses a position information generation system in which an on-board unit transmits a first signal to a first communication unit and a second communication unit of a roadside unit, receives second signals transmitted by the first communication unit and the second communication unit of the roadside unit, calculates the distance from the first communication unit of the on-board unit, calculates the distance from the second communication unit of the on-board unit, and specifies the intersection of circles or spheres centered on the positions of the first communication unit and the second communication unit as its own position to generate position information.

[0005] Patent Document 3 discloses a host vehicle position estimation device including: a vehicle position estimation unit that calculates the position of a vehicle based on the output of a sensor that detects vehicle behavior; a wireless position estimation unit that communicates with a wireless device installed at an arbitrary position to calculate the relative position between the vehicle and the wireless device; and a position estimation parameter correction unit that corrects parameters used for calculating at least vehicle position and turning angle information in the vehicle position estimation unit, wherein the position estimation parameter correction unit corrects the parameters by comparing the movement amount of the vehicle calculated by the wireless position estimation unit with the movement amount of the vehicle calculated by the vehicle position estimation unit.

[0006] Non-patent document 1 describes positioning technology using vehicle-to-infrastructure and vehicle-to-vehicle communication in fifth-generation mobile communication systems. It also states that the configuration required for positioning can be reduced by using distributed antennas. Furthermore, it states that if a vehicle is equipped with three antennas, positioning can be performed with a single roadside unit. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2008-292316 [Patent Document 2] Japanese Patent Publication No. 2009-198374 [Patent Document 3] Patent No. 7591463 [Non-patent literature]

[0008] [Non-Patent Document 1] “System Architecture and Solution Development; High-Accuracy Positioning for CV2X”, 5GAA Automotive Association Technical Report, 2021 / 2 / 9. [Overview of the project] [Problems that the invention aims to solve]

[0009] However, there is room for improvement in accurately determining the relative position between a vehicle and a roadside machine when a vehicle passes over it, using a simple configuration and simple processing procedure.

[0010] The purpose of this disclosure is to provide a positioning device, a positioning method, and a positioning program that can accurately determine the relative position between a vehicle and a roadside unit with a simple configuration and a simple processing procedure when a vehicle passes a roadside unit. [Means for solving the problem]

[0011] To achieve the above objective, the positioning device according to the first embodiment includes: a plurality of antennas provided on a vehicle and receiving transmission signals from a roadside unit installed on the roadside; a path difference measurement unit that measures the path difference from the roadside unit to each of the antennas based on the difference in arrival time when each of the antennas receives the transmission signals from the roadside unit; a relative position calculation unit that calculates the relative position change of each of the antennas due to the movement of the vehicle during the measurement time of the path difference; and a positioning calculation unit that calculates the position of the roadside unit based on the path difference measured by the path difference measurement unit at at least two different positions and the relative position change of the vehicle between the different positions calculated by the relative position calculation unit.

[0012] According to the first embodiment, the path difference from the roadside unit to each antenna is measured based on the arrival time difference when the transmitted signal from the roadside unit is received by multiple antennas installed on the vehicle, the relative position change of each antenna due to the movement of the vehicle during the measurement time of the path difference is calculated, and the position of the roadside unit is calculated based on the path difference measured at at least two different positions and the relative position change of the vehicle between the different positions calculated by the relative position calculation unit. As a result, when a vehicle passes the roadside unit, the relative position between the vehicle and the roadside unit can be accurately determined with a simple configuration and a simple processing procedure.

[0013] The positioning device according to the second embodiment further comprises a roadside device passage determination unit that determines whether or not the vehicle has passed the roadside device, and the positioning calculation unit determines the position of the roadside device using the path difference measured at least once before and once after the vehicle has passed the roadside device.

[0014] According to the second embodiment, the influence of path difference errors can be suppressed, so the position of the roadside unit can be determined with high accuracy.

[0015] The positioning device according to the third embodiment further comprises a path difference selection unit that selects from among the path differences measured by the path difference measurement unit at multiple locations a combination of at least two path differences in which the hyperbolas obtained from the measured path differences and the position of the vehicle intersect at an angle closer to a right angle, and the positioning calculation unit calculates the position of the roadside unit using the set of path differences selected by the path difference selection unit.

[0016] According to the third embodiment, since a combination of path differences that is less affected by path difference errors can be selected, the position of the roadside unit can be determined with high accuracy.

[0017] In the positioning device according to the fourth embodiment, the relative position calculation unit determines the change in the vehicle's position during the measurement time, including the turning motion of the vehicle, from the vehicle speed and the change in the vehicle's orientation.

[0018] According to the fourth embodiment, the relative position change during the measurement of the path difference can be determined with greater accuracy.

[0019] In the fifth embodiment of the positioning device, in the positioning device according to the second embodiment, if the plurality of antennas are mounted spaced apart in the longitudinal direction of the vehicle and the roadside unit is installed beside or directly above the road, the roadside unit passage determination unit determines whether or not the roadside unit has been passed by detecting a reversal of the sign of the path difference before and after the passage of the roadside unit.

[0020] According to the fifth embodiment, when multiple antennas are mounted spaced apart in the front-rear direction of the vehicle, and a roadside unit is installed beside or directly above the road, it is possible to determine whether or not the vehicle has passed the roadside unit.

[0021] In the positioning device according to the sixth embodiment, in the positioning device according to the second embodiment, if the plurality of antennas are mounted spaced apart in the vehicle width direction and the roadside unit is installed next to the road, the roadside unit passage determination unit determines whether or not the roadside unit has been passed by detecting that the path difference is maximum when the roadside unit is passed.

[0022] According to the sixth aspect, when a plurality of antennas are mounted spaced apart in the vehicle width direction of the vehicle and the roadside unit is installed beside a road, it can be determined whether the vehicle has passed the roadside unit.

[0023] A positioning device according to a seventh aspect is the positioning device according to the first aspect, wherein the positioning calculation unit calculates the position of the roadside unit by hyperbolic positioning or azimuth estimation from the position of the antenna and the path difference.

[0024] According to the seventh aspect, the position of the roadside unit can be specified from the position of the antenna and the path difference.

[0025] A positioning method according to an eighth aspect is a method wherein a computer measures a path difference from the roadside unit to each of said antennas based on a difference in arrival times when a plurality of antennas provided on the vehicle that respectively receive transmission signals from the roadside unit installed on a roadside receive the signals, calculates a relative position change of each said antenna accompanying movement of said vehicle between measurement times of said path difference, and performs processing of calculating the position of said roadside unit based on said path differences measured at at least two different positions and the relative position change of said vehicle between said different positions.

[0026] According to the eighth aspect, the path difference from the roadside unit to each antenna is measured based on the arrival time difference when the transmission signals from the roadside unit are respectively received by the plurality of antennas provided on the vehicle, the relative position change of each antenna accompanying the movement of the vehicle between the measurement times of the path difference is calculated, and the position of the roadside unit is calculated based on the path differences measured at at least two different positions and the relative position change of the vehicle between the different positions calculated by the relative position calculation unit. This makes it possible to obtain the relative position between the vehicle and the roadside unit with high accuracy by a simple configuration and a simple processing procedure when the vehicle passes the roadside unit.

[0027] The positioning program according to the ninth embodiment causes a computer to perform the following process: measure the path difference from the roadside unit to each of the antennas based on the difference in arrival time when the transmission signal from the roadside unit installed on the roadside is received by each of the multiple antennas installed on the vehicle; calculate the relative position change of each of the antennas due to the movement of the vehicle during the time period in which the path difference is measured; and calculate the position of the roadside unit based on the path difference measured at at least two different locations and the relative position change of the vehicle between the different locations.

[0028] According to the ninth embodiment, the path difference from the roadside unit to each antenna is measured based on the arrival time difference when the transmitted signal from the roadside unit is received by multiple antennas installed on the vehicle, the relative position change of each antenna due to the movement of the vehicle during the measurement time of the path difference is calculated, and the position of the roadside unit is calculated based on the path difference measured at at least two different positions and the relative position change of the vehicle between the different positions calculated by the relative position calculation unit. As a result, when a vehicle passes the roadside unit, the relative position between the vehicle and the roadside unit can be accurately determined with a simple configuration and a simple processing procedure. [Effects of the Invention]

[0029] As described above, the present invention provides a positioning device, a positioning method, and a positioning program that can accurately determine the relative position between a vehicle and a roadside unit with a simple configuration and a simple processing procedure when a vehicle passes over the roadside unit. [Brief explanation of the drawing]

[0030] [Figure 1] This figure shows a schematic configuration of a vehicle equipped with a positioning device according to this embodiment. [Figure 2] This is a block diagram showing the schematic configuration of the positioning device according to this embodiment. [Figure 3] This is a functional block diagram showing the functional configuration of the positioning device according to the first embodiment. [Figure 4] This diagram shows a scene where a moving vehicle passes in front of a roadside machine. [Figure 5]This figure shows an example of how the path difference from the roadside unit to the vehicle's two antennas changes with respect to the vehicle's position. [Figure 6] This diagram shows hyperbolic positioning before and after a vehicle passes a roadside positioning station. [Figure 7] This diagram shows hyperbolic positioning before a vehicle passes a roadside positioning device. [Figure 8] This flowchart shows an example of the processing flow performed by the positioning device according to this embodiment. [Figure 9] This is a functional block diagram showing the functional configuration of the positioning device according to the second embodiment. [Figure 10] This figure shows the hyperbola resulting from the difference in the path taken by a vehicle before and after passing a roadside machine, assuming no path error. [Figure 11] This figure shows a hyperbola formed by the path difference between two points only before a vehicle passes a roadside machine, assuming no path error. [Figure 12] This figure shows the hyperbola resulting from the difference in the path a vehicle takes before and after passing a roadside machine, when a path error of ±0.1 is added. [Figure 13] This figure shows the hyperbola resulting from the path difference between two points only before the vehicle passes the roadside equipment, when a path error of ±0.1 is added. [Figure 14] This flowchart shows an example of the processing flow performed by the positioning device according to this embodiment. [Figure 15] This is a functional block diagram showing the functional configuration of the positioning device according to the third embodiment. [Figure 16] This flowchart shows an example of the processing flow performed by the positioning device according to this embodiment. [Figure 17] This is a functional block diagram showing the functional configuration of the positioning device according to the fourth embodiment. [Figure 18] This diagram shows hyperbolic positioning based on the difference in the path taken by the vehicle before and after it passes a roadside unit, with antennas positioned in the vehicle width direction. [Figure 19] This figure shows an example of hyperbolic positioning based on the difference in the path taken by a vehicle before and after it passes a roadside unit, with antennas positioned in the vehicle width direction. [Figure 20]This figure shows an example of hyperbolic positioning using the path difference between two points only before the vehicle passes the roadside unit, with antennas positioned in the vehicle width direction. [Figure 21] This diagram illustrates direction estimation using a typical array antenna. [Figure 22] This is a diagram to explain hyperbolic positioning. [Figure 23] This diagram compares direction estimation and hyperbolic positioning. [Figure 24] This diagram shows a case where there is a difference in height between the roadside antenna and the vehicle's antenna. [Modes for carrying out the invention]

[0031] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, a positioning device that determines the relative positional relationship between a roadside unit and a vehicle using road-to-vehicle communication will be described as an example. Figure 1 is a diagram showing the schematic configuration of a vehicle equipped with the positioning device according to this embodiment. Figure 2 is a block diagram showing the schematic configuration of the positioning device according to this embodiment.

[0032] The positioning device 10 according to this embodiment is mounted on a vehicle 12 and is connected to a plurality of antennas (antenna A14A, antenna B14B) 14 provided on the vehicle 12.

[0033] Multiple antennas 14 are provided for communication with roadside units 18 installed alongside the road. The arrangement of antennas A14A and B14B is described as an example where they are spaced apart in the front-rear direction of the vehicle, but they may also be spaced apart in the vehicle width direction. In this embodiment, antenna A14A is located in front of the vehicle 12, antenna B14B is located behind the vehicle 12, and the distance between antennas A14A and B14B is known. Furthermore, the installation location information of the roadside unit 18 is also known.

[0034] As shown in Figure 2, the positioning device 10 according to this embodiment is composed of a general-purpose microcomputer including a CPU (Central Processing Unit) 10A, ROM (Read Only Memory) 10B, RAM (Random Access Memory) 10C, storage 10D, interface (I / F) 10E, and bus 10F.

[0035] The CPU 10A is the central processing unit, which executes various programs and controls various parts. Specifically, the CPU 10A reads programs from ROM 10B or storage 10D and executes them using RAM 10C as the working area. The CPU 10A performs various control and calculation processes according to the programs recorded in ROM 10B or storage 10D.

[0036] ROM 10B stores various programs and data. RAM 10C temporarily stores programs or data as a working area. Storage 10D is composed of an HDD (Hard Disk Drive) or SSD (Solid State Drive), etc., and stores various programs and data. In this embodiment, ROM 10B or storage 10D stores a positioning program that performs positioning calculations.

[0037] Antenna A14A, antenna B14B, and wheel speed sensor 16 are connected to I / F10E, and the signals from antennas A14A and B14B, as well as the detection result of the wheel speed of the vehicle 12 detected by the wheel speed sensor 16, are input to the positioning device 10.

[0038] (First Embodiment) Next, the functional configuration of the positioning device 10 according to the first embodiment will be described. Figure 3 is a functional block diagram showing the functional configuration of the positioning device 10 according to this embodiment.

[0039] In this embodiment, the positioning device 10 has the functions of a path difference measurement unit 20, a relative position calculation unit 22, and a positioning calculation unit 24, by having the CPU 10A load a positioning program stored in ROM 10B or storage 10D into RAM 10C and execute it.

[0040] The path difference measurement unit 20 measures the path difference from the roadside unit 18 to each antenna 14 based on the difference in arrival time when each antenna 14 receives the transmission signal transmitted from the roadside unit 18.

[0041] The relative position calculation unit 22 calculates the relative position change of each antenna 14 due to the movement of the vehicle 12 during the measurement time of the path difference. Specifically, the relative position calculation unit 22 determines the distance traveled during the measurement time by integrating the wheel speed, which is an example of the vehicle speed detected by the wheel speed sensor 16, and determines the position change of each antenna 14 due to the movement of the vehicle 12 during the measurement time of the path difference.

[0042] The positioning calculation unit 24 calculates the position of the roadside unit 18 based on the path difference measured at at least two different vehicle positions and the relative position of the vehicle between those different positions.

[0043] Next, we will explain how the relative positional relationship between the roadside unit 18 and the vehicle 12 is determined by the positioning device 10 according to this embodiment. Figure 4 shows a scene in which a moving vehicle 12 passes in front of the roadside unit 18. Here, we consider the case where two antennas (antenna A14A and antenna B14B) 14 are installed on the vehicle 12 at a distance apart in the front-rear direction of the vehicle 12. The antenna arrangement and the distance between the antennas are assumed to be known. The roadside unit 18 is also assumed to be installed next to the road, and the installation position information of the roadside unit 18 is assumed to be known. Furthermore, below, the direction of vehicle travel will be denoted as X, the vehicle width direction as Y, the position when the vehicle 12 passes in front of the roadside unit 18 will be denoted as X=0, and the bearing from the vehicle 12 to the roadside unit 18 will be denoted as θ.

[0044] Figure 5 shows an example of how the path difference from the roadside unit 18 to the two antennas 14 on the vehicle 12 changes with respect to the position of the vehicle 12. The path difference can be determined from the arrival time difference of the transmitted signals sent from the roadside unit 18, and as shown in Figure 5, the path difference changes depending on the position of the vehicle 12.

[0045] When vehicle 12 enters the communication area of ​​roadside unit 18, antennas A14A and B14B each receive the signal transmitted from roadside unit 18. Since the distance from roadside unit 18 to antenna A14A is different from the distance from roadside unit 18 to antenna B14B, a difference in the signal arrival time to each antenna 14 occurs corresponding to the difference in distance (path difference). Therefore, the path difference measurement unit 20 measures this arrival time difference and calculates the path difference by multiplying it by the propagation speed of radio waves (speed of light). At the same time, it records the measured time.

[0046] As the vehicle 12 moves, the position of the antenna 14 also moves. The relative position calculation unit 22 calculates the distance the antenna 14 moves as the vehicle 12 moves by integrating the wheel speed. Based on the measurement times of the path difference, the distance traveled between measurement times can be calculated.

[0047] As vehicle 12 travels, the route difference measurement unit 20 repeatedly calculates the time difference to arrive at each location and records the route difference and the measurement time. If there is a route difference at at least two points, positioning calculation becomes possible.

[0048] The positioning calculation unit 24 determines the position of the roadside unit 18 relative to the vehicle 12's trajectory based on the path difference measured at at least two points. Hyperbolic positioning is used to determine the position of the roadside unit 18.

[0049] Figures 6 and 7 show conceptual diagrams of hyperbolic positioning. Figure 6 shows hyperbolic positioning before and after vehicle 12 passes roadside unit 18, and Figure 7 shows hyperbolic positioning before vehicle 12 passes roadside unit 18. In Figures 6 and 7, the path difference at time t1 is shown as path difference t1, and the path difference at time t2 is shown as path difference t2.

[0050] The roadside unit 18 lies on a hyperbola corresponding to the path difference between the position of the antenna 14, which corresponds to the position of the vehicle 12, and the roadside unit 18. Therefore, the position of the roadside unit 18 is determined as the intersection of the hyperbolas, as shown in Figures 6 and 7. It is assumed that the left or right side of the road where the roadside unit 18 is installed can be obtained in advance from the installation information of the roadside unit 18.

[0051] In this way, the position of the roadside unit 18 is determined as the intersection point of the hyperbola, so the position of the roadside unit 18 relative to the vehicle's trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure. This allows the lateral distance of the vehicle to the roadside unit 18 when it passes it to be known, so for example, when traveling on a multi-lane road, the lane the vehicle is traveling in can be identified. Furthermore, it becomes possible to correct the position of the travel trajectory based on the installation position information of the roadside unit 18.

[0052] Next, we will describe the specific processing performed by the positioning device 10 according to this embodiment, which is configured as described above. Figure 8 is a flowchart showing an example of the processing flow performed by the positioning device 10 according to this embodiment. Note that the processing in Figure 8 starts, for example, when a vehicle 12 enters the communication area of ​​the roadside unit 18 and the antenna 14 receives a transmission signal from the roadside unit 18.

[0053] In step 100, the CPU 10A performs a path difference measurement and proceeds to step 102. Specifically, the path difference measurement unit 20 measures the path difference from the roadside unit 18 to each antenna 14 based on the difference in arrival times when each antenna 14 receives the transmission signal transmitted from the roadside unit 18. More precisely, it stores the path difference obtained from the measurement time and the TDOA (Time Difference of Arrival) measurement result between the two antennas 14.

[0054] In step 102, the CPU 10A calculates the distance traveled and proceeds to step 104. Specifically, the relative position calculation unit 22 calculates the change in the relative position of the antenna 14 due to the movement of the vehicle 12 during the measurement time (distance traveled during the measurement time) by integrating the wheel speed detected by the wheel speed sensor 16.

[0055] In step 104, the CPU 10A determines whether the measurement information has been stored and whether positioning calculations are possible. If the determination is negative, the process returns to step 100 and the above process is repeated. If the determination is positive, the process proceeds to step 106. That is, measurements are repeated until the information necessary for calculating the position of the roadside unit 18 can be collected from the stored path difference and relative position information.

[0056] In step 106, the CPU 10A performs a positioning calculation and completes the series of processes. Specifically, the positioning calculation unit 24 uses the path difference measured at at least two different vehicle positions and the relative position of the vehicle between them to determine the position of the roadside unit 18 relative to the vehicle 12 by hyperbolic positioning.

[0057] By performing this process, the position of the roadside unit 18 relative to the vehicle's trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure.

[0058] (Second Embodiment) Next, the functional configuration of the positioning device 10 according to the second embodiment will be described. Figure 9 is a functional block diagram showing the functional configuration of the positioning device 10 according to the second embodiment.

[0059] In this embodiment, the functions of the roadside machine passage determination unit 26 are further added compared to the first embodiment.

[0060] In this embodiment, similar to the first embodiment, the route difference measurement unit 20 repeatedly measures the arrival time difference as the vehicle 12 travels, and records the route difference and the measurement time.

[0061] The roadside unit passage determination unit 26 determines whether or not the vehicle 12 has passed in front of the roadside unit 18 based on the change in the path difference measured by the path difference measurement unit 20. From the change in the path difference with respect to the position of the vehicle 12 shown in Figure 5, the vehicle 12 passes in front of the roadside unit 18 when its position is 0. In Figure 5, the path difference is calculated by subtracting the distance between antenna B14B and the roadside unit 18 from the distance between antenna A14A and the roadside unit 18. Before the vehicle 12 passes the roadside unit 18, the path difference is negative, and after the vehicle 12 passes the roadside unit 18, the path difference becomes positive. Therefore, by detecting the sign inversion, it is possible to determine whether or not the vehicle has passed the roadside unit 18.

[0062] The roadside unit 18 continues to measure the path difference even after the vehicle 12 has passed it, and stores the path difference used for positioning calculations. In this embodiment, positioning calculations are performed after acquiring the path difference even after the vehicle has passed the roadside unit.

[0063] In this embodiment, the positioning calculation unit 24 uses the path difference measured at least once before and once after the vehicle 12 passes the roadside unit 18 to determine the position of the roadside unit 18 relative to the vehicle's travel trajectory.

[0064] To determine the position of the roadside unit 18, hyperbolic positioning is used, similar to the first embodiment. By using the difference in the path before and after the passage of the roadside unit 18, hyperbolic positioning is obtained as shown in Figure 6.

[0065] Here, we will explain the effect of using the difference in the path taken by vehicle 12 before and after passing the roadside machine 18.

[0066] The position of the roadside unit 18 can be determined by the intersection of the hyperbolas. For example, as shown in Figure 10, the position of the roadside unit 18 can be determined by finding the intersection of the hyperbolas at the positions before and after the vehicle 12 passes the roadside unit 18. Figure 10 shows the hyperbolas resulting from the path difference before and after the vehicle 12 passes the roadside unit 18, assuming no path error.

[0067] Furthermore, in principle, the position of the roadside unit 18 can be determined using the path difference between two points, either before or after the vehicle 12 passes the roadside unit 18. For example, as shown in Figure 11, the position of the roadside unit 18 can be determined using the path difference between two points, either before the vehicle 12 passes the roadside unit 18. Figure 11 shows a hyperbola resulting from the path difference between two points, given that there is no path error, before the vehicle 12 passes the roadside unit 18.

[0068] However, in this case, as shown in Figure 7, the angle at which the hyperbolas intersect becomes shallower, making it more susceptible to the effects of path difference errors, and reducing the accuracy of determining the position of the roadside unit 18. For example, if there is a path error, a position error occurs, as shown in Figures 12 and 13. As shown in Figure 13, when using the path difference of two points only before the vehicle passes the roadside unit 18, the range in which position errors occur (hatched area in Figures 12 and 13) becomes wider than when using the path difference before and after the vehicle passes the roadside unit 18, as shown in Figure 12, making it more susceptible to the effects of path difference errors. Figure 12 shows the hyperbolas due to the path difference before and after the vehicle 12 passes the roadside unit 18 when a path error of ±0.1 is added. On the other hand, Figure 13 shows the hyperbolas due to the path difference of two points only before the vehicle 12 passes the roadside unit 18 when a path error of ±0.1 is added.

[0069] Therefore, in this embodiment, the difference in the path taken by the vehicle 12 before and after it passes the roadside unit 18 is used. As a result, the angle at which the two hyperbolas intersect becomes deeper, which minimizes the effect of path difference errors and allows the position of the roadside unit 18 to be determined with high accuracy.

[0070] Thus, in this embodiment as well, the position of the roadside unit 18 relative to the vehicle's trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure. As a result, the lateral distance of the vehicle to the roadside unit 18 when it passes it can be determined, so for example, when traveling on a multi-lane road, the lane the vehicle is traveling in can be identified. Furthermore, it is possible to correct the position of the travel trajectory based on the installation position information of the roadside unit 18.

[0071] Next, we will describe the specific processing performed by the positioning device 10 according to this embodiment. Figure 14 is a flowchart showing an example of the processing flow performed by the positioning device 10 according to this embodiment. Note that the processing in Figure 14 starts, for example, when a vehicle 12 enters the communication area of ​​the roadside unit 18 and the antenna 14 receives a transmission signal from the roadside unit 18. Furthermore, the same reference numerals are used to describe the same processing as in Figure 8.

[0072] In step 100, the CPU 10A performs a path difference measurement and proceeds to step 102. Specifically, the path difference measurement unit 20 measures the path difference from the roadside unit 18 to each antenna 14 based on the difference in arrival times when each antenna 14 receives the transmission signal transmitted from the roadside unit 18. More precisely, it stores the path difference obtained from the measurement time and the TDOA (Time Difference of Arrival) measurement result between the two antennas 14.

[0073] In step 102, the CPU 10A calculates the distance traveled and proceeds to step 108. Specifically, the relative position calculation unit 22 calculates the change in the relative position of the antenna 14 due to the movement of the vehicle 12 during the measurement time (distance traveled during the measurement time) by integrating the wheel speed detected by the wheel speed sensor 16.

[0074] In step 108, the CPU 10A performs a roadside unit passage determination and proceeds to step 110. Specifically, the roadside unit passage determination unit 26 determines whether the vehicle 12 has passed in front of the roadside unit 18 based on the path difference and relative position information measured and stored by the path difference measurement unit 20. If the antennas 14 are positioned in front of and behind the vehicle 12, this determination can be made by observing the reversal of the sign of the path difference before and after the vehicle 12 has passed the roadside unit 18.

[0075] In step 110, the CPU 10A determines whether there is information on the difference in the route before and after the vehicle 12 passes the roadside unit 18. If this determination is denied, the process returns to step 100 and the above processing is repeated. If the determination is affirmative, the process proceeds to step 112. That is, measurements are repeated until information necessary for positioning calculations before and after the vehicle passes the roadside unit 18 can be collected from the stored route difference and relative position information.

[0076] In step 112, the CPU 10A performs positioning calculations to complete the series of processes. Specifically, the positioning calculation unit 24 uses the difference in the path before and after the vehicle 12 passes the roadside unit 18, as well as the relative position, to determine the position of the roadside unit 18 relative to the vehicle 12 using hyperbolic positioning.

[0077] By performing the processing in this manner, the position of the roadside unit 18 relative to the vehicle 12's travel trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure.

[0078] (Third embodiment) Next, the functional configuration of the positioning device 10 according to the third embodiment will be described. Figure 15 is a functional block diagram showing the functional configuration of the positioning device 10 according to the third embodiment.

[0079] In this embodiment, the functionality of the route difference selection unit 28 is further enhanced compared to the first embodiment. After the route difference measurement unit 20 measures and stores the route difference information necessary for positioning calculation, the route difference selection unit 28 selects from among the route differences measured by the route difference measurement unit 20 at multiple locations a combination of at least two route differences in which the measured route differences and the hyperbolas obtained from the position of the vehicle 12 intersect at an angle closer to a right angle. If the route difference selection unit 28 determines that the angle at which the hyperbolas intersect is sufficiently close to orthogonal, it uses that combination to perform positioning calculation by hyperbolic positioning in the positioning calculation unit 24.

[0080] As the hyperbolas intersect at an angle that is nearly orthogonal, the position of the roadside unit 18 can be determined with high accuracy, as it is less susceptible to path difference errors, as described in the second embodiment.

[0081] Thus, in this embodiment as well, the position of the roadside unit 18 relative to the vehicle's trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure. As a result, the lateral distance of the vehicle to the roadside unit 18 when it passes it can be determined, so for example, when traveling on a multi-lane road, the lane the vehicle is traveling in can be identified. Furthermore, it is possible to correct the position of the travel trajectory based on the installation position information of the roadside unit 18.

[0082] Next, we will describe the specific processing performed by the positioning device 10 according to this embodiment. Figure 16 is a flowchart showing an example of the processing flow performed by the positioning device 10 according to this embodiment. Note that the processing in Figure 16 starts, for example, when a vehicle 12 enters the communication area of ​​the roadside unit 18 and the antenna 14 receives a transmission signal from the roadside unit 18. Furthermore, the same reference numerals are used to describe the same processing as in Figure 8.

[0083] In step 100, the CPU 10A performs a path difference measurement and proceeds to step 102. Specifically, the path difference measurement unit 20 measures the path difference from the roadside unit 18 to each antenna 14 based on the difference in arrival times when each antenna 14 receives the transmission signal transmitted from the roadside unit 18. More precisely, it stores the path difference obtained from the measurement time and the TDOA (Time Difference of Arrival) measurement result between the two antennas 14.

[0084] In step 102, the CPU 10A calculates the distance traveled and proceeds to step 114. Specifically, the relative position calculation unit 22 calculates the change in the relative position of the antenna 14 due to the movement of the vehicle 12 during the measurement time (distance traveled during the measurement time) by integrating the wheel speed detected by the wheel speed sensor 16.

[0085] In step 114, the CPU 10A selects the path difference to be used for positioning calculation and proceeds to step 116. That is, the path difference selection unit 28 selects a combination of two hyperbolas that intersect at an angle close to orthogonal as the set of path difference information to be used for positioning calculation.

[0086] In step 116, the CPU 10A determines whether the intersection angle of the hyperbolas is close to orthogonal. This determination, for example, determines whether the intersection angle of the hyperbolas is close to orthogonal and greater than a threshold. If the determination is negative, the process returns to step 100 and the above processing is repeated. If the determination is positive, the process proceeds to step 118. That is, the CPU 10A determines whether the set of hyperbolas used for positioning calculations is sufficiently close to orthogonal based on the stored path difference and relative position information.

[0087] In step 118, the CPU 10A performs positioning calculations to complete the series of processes. Specifically, the positioning calculation unit 24 uses the difference in the path before and after the vehicle 12 passes the roadside unit 18, as well as the relative position, to determine the position of the roadside unit 18 relative to the vehicle 12 using hyperbolic positioning.

[0088] By performing the processing in this manner, the position of the roadside unit 18 relative to the vehicle 12's travel trajectory can be accurately determined with a simple configuration of one roadside unit 18 and two antennas 14 on the vehicle 12, and with a simple processing procedure.

[0089] (Fourth Embodiment) Next, the functional configuration of the positioning device 10 according to the fourth embodiment will be described. Figure 17 is a functional block diagram showing the functional configuration of the positioning device 10 according to the fourth embodiment.

[0090] In this embodiment, the functions of the vehicle motion estimation unit 30 are further added compared to the first embodiment. The functions of the vehicle motion estimation unit 30 may be added to the second or third embodiment.

[0091] In the fourth embodiment, in addition to the wheel speed sensor 16, the vehicle is equipped with state sensors 32 such as a gyroscope and an acceleration sensor to detect the vehicle's state, and the vehicle motion estimation unit 30 estimates the vehicle's motion, including changes in the vehicle's attitude and orientation. The relative position calculation unit 22 then determines the change in the vehicle's position during the measurement period, including the vehicle's turning motion, from the vehicle speed and the change in the vehicle's orientation. As a result, the relative position calculation unit 22 can more accurately determine the change in the relative position of each antenna 14 due to the movement of the vehicle 12 during the measurement period of the path difference.

[0092] For two-dimensional motion estimation, only the wheel speed sensor 16 and the gyroscope sensor are sufficient. Adding an acceleration sensor further enables the estimation of changes in posture.

[0093] This allows the position of the roadside unit 18 to be accurately determined by hyperbolic positioning, even when changing lanes or turning vehicles (when the roadside unit 18 is installed on curved roads, etc.).

[0094] In the embodiments described above, the arrangement of the two antennas 14 installed on the vehicle 12 was shown to be in the front-rear direction of the vehicle 12. However, as shown in Figures 18-20, they may also be arranged in the vehicle width direction. When arranged in the vehicle width direction, the change in path difference accompanying the movement of the vehicle 12 (the change from path difference t1 at time t1 to path difference t2 at time t2) is such that the path difference is approximately 0 at long distances, increases as the vehicle approaches the roadside unit 18, and decreases as the vehicle moves away after passing the roadside unit 18. Therefore, in the second embodiment, when the antennas 14 are arranged in the vehicle width direction, the roadside unit passage determination unit 26 can determine whether or not the roadside unit has been passed by detecting from the change in the magnitude of the path difference that the path difference is maximum when the roadside unit 18 is passed. The same effect is also observed with respect to the angles at which the hyperbolas intersect. As shown in Figures 18 and 19, by selecting a combination where the intersection angles of the hyperbolas are close to orthogonal, the position of the roadside unit 18 can be determined with high accuracy. Figure 18 shows hyperbolic positioning based on the path difference before and after the vehicle 12 passes the roadside unit 18, with the antenna 14 positioned in the vehicle width direction. Figure 19 shows an example of hyperbolic positioning based on the path difference before and after the vehicle 12 passes the roadside unit 18, with the antenna 14 positioned in the vehicle width direction. Figure 20 shows an example of hyperbolic positioning based on the path difference between two points only before the vehicle 12 passes the roadside unit 18, with the antenna 14 positioned in the vehicle width direction.

[0095] Furthermore, in each of the above embodiments, there may be two or more antennas 14 installed on the vehicle 12. For example, by arranging three antennas in a triangular shape, multiple path differences can be measured by changing the combination of antennas 14 at a single measurement point, and in principle, the position of the roadside unit 18 can be determined.

[0096] Furthermore, in each of the above embodiments, when the relative position calculation unit 22 determines the relative position change of the antenna 14 as the vehicle 12 moves, it assumes that the vehicle 12 is traveling in a straight line and uses the distance traveled. As can be seen from Figure 5, the change in path difference is large in the section of several tens of meters before and after passing near the roadside unit 18, and this method is intended to be implemented in this section. In normal traffic conditions on expressways and motorways, this section is passed through in less than a few seconds, so in most cases it is not a problem to approximate it as straight-line driving.

[0097] Furthermore, although the above embodiments show examples in which the positioning calculation unit 24 performs hyperbolic positioning, the two antennas 14 installed on the vehicle may be considered similarly to a two-element array antenna with wide element spacing, and direction estimation may be performed from the path difference. By using the period before and after the passage of the roadside unit 18, the effect of the direction obtained from the two points intersecting at a deep angle can be obtained similarly. However, when the vehicle 12 passes near the roadside unit 18, the distance between the transmitting and receiving points is short, so the direction from the two antennas 14 will not be equal, which becomes a source of error. For this reason, hyperbolic positioning has an advantage in terms of positional accuracy.

[0098] Here, we will explain the difference between direction estimation using path difference and hyperbolic positioning. Figure 21 is a diagram illustrating direction estimation using a typical array antenna, etc. Figure 22 is a diagram illustrating hyperbolic positioning.

[0099] In the general direction estimation method shown in Figure 21, the direction is estimated from the path difference between antennas, assuming that the incoming wave can be approximated as a plane wave. This is the method used for direction estimation with array antennas, etc.

[0100] On the other hand, in hyperbolic positioning shown in Figure 22, the incoming wave is assumed to propagate as a spherical wave from the wave source, which is the transmission point, and the hyperbola at the transmission point's position is determined.

[0101] In the case of vehicle-to-infrastructure communication, the distance to the roadside unit 18 is shorter than the distance d between antennas, so hyperbolic positioning is superior to direction estimation because it results in smaller positional errors.

[0102] Figure 23 shows a comparison of direction estimation and hyperbolic positioning. In Figure 23, the distance between antennas is 5m, the roadside unit position is (X,Y)=(0,10), and the measurement error of the path difference is assumed to be zero.

[0103] Each intersection point represents the estimated position of the roadside unit 18. However, from the enlarged view in Figure 23, it can be seen that while the intersection of the hyperbola is at the position of the roadside unit 18, the intersection of the direction estimation is offset from the position of the roadside unit 18, indicating a positional error. This is because the distance to the roadside unit 18 is short relative to the distance d between the antennas.

[0104] In the above embodiments, the path difference used by the positioning calculation unit 24 was set to include one or more measurements before and after the vehicle 12 passes the roadside unit 18. However, if the distance traveled between the two measurement points is extremely small, the intersection angle may become shallow. Therefore, a set of path differences in which the antenna travel distance (relative position) is greater than or equal to a predetermined distance may be used. Alternatively, since the approximate direction of the roadside unit 18 can be determined from the path difference, the range of path difference values ​​used for positioning may be limited.

[0105] Furthermore, although the above embodiments were described using two-dimensional positioning on a plane, generally the height of the roadside unit 18's antenna is often higher than the height of the vehicle's antenna 14. If the height of the antenna 14 is known in advance, the lateral position of the vehicle 12 when it passes the roadside unit 18 can be corrected based on the difference in height between the roadside unit 18 and the antenna 14. Figure 24 shows the case where there is a difference in height between the roadside unit 18's antenna and the vehicle 12's antenna 14. The distance between the roadside unit 18 and the vehicle 12 when they pass, as determined by this method, is the distance of the straight line connecting the roadside unit 18 and the vehicle 12's antenna 14 in the figure. For example, if the distance from the roadside unit 18 is 10m and the difference in antenna height is 6m, the lateral distance of the vehicle from the roadside unit 18 can be calculated as 8m.

[0106] Furthermore, although the above embodiment described a CPU as an example of a processor, the term "processor" refers to a broader type of processor, including general-purpose processors (such as CPUs) and specialized processors (such as GPUs: Graphics Processing Units, ASICs: Application Specific Integrated Circuits, FPGAs: Field Programmable Gate Arrays, and programmable logic devices).

[0107] Furthermore, the operation of the processor in the above embodiments may not be performed by a single processor, but may be performed by multiple processors located in physically separate locations working together. Also, the order of the processor operations is not limited to the order described in each of the above embodiments, but may be changed as appropriate.

[0108] Furthermore, the processing performed by the positioning device 10 according to the above embodiment may be software-based processing, hardware-based processing, or a combination of both.

[0109] The program of this application can be provided as a program product. A program product includes any form of product for providing a program. For example, a program product includes a program provided via a network such as the Internet, and non-temporary computer-readable recording media such as CD-ROMs and DVDs on which the program is stored.

[0110] Furthermore, the present invention is not limited to the above, and it is of course possible to implement it in various modified forms without departing from its spirit.

[0111] This disclosure may adopt the following embodiments: (1) Multiple antennas are installed on the vehicle to receive transmission signals from roadside units installed on the roadside, A path difference measuring unit measures the path difference from the roadside unit to each of the antennas based on the difference in arrival time when the transmitted signal from the roadside unit is received by each of the antennas, A relative position calculation unit calculates the relative position change of each antenna due to the movement of the vehicle during the measurement time of the path difference, A positioning calculation unit calculates the position of the roadside unit based on the path difference measured by the path difference measurement unit at at least two different locations and the relative position change of the vehicle between the different locations calculated by the relative position calculation unit. A positioning device equipped with the following features.

[0112] (2) The system further includes a roadside device passage determination unit that determines whether or not the vehicle has passed the roadside device. The positioning device according to (1), wherein the positioning calculation unit determines the position of the roadside unit using the path difference measured at least once before and once after the vehicle passes the roadside unit.

[0113] (3) The system further includes a path difference selection unit that selects from among the path differences measured by the path difference measurement unit at multiple locations a combination of at least two path differences in which the measured path differences and the hyperbolas obtained from the position of the vehicle intersect at an angle closer to a right angle. The positioning device according to (1), wherein the positioning calculation unit calculates the position of the roadside unit using the set of path differences selected by the path difference selection unit.

[0114] (4) The positioning device according to any one of (1) to (3), wherein the relative position calculation unit determines the change in the vehicle's position during the measurement time, including the vehicle's turning motion, from the vehicle speed and the change in the vehicle's orientation.

[0115] (5) When the plurality of antennas are mounted spaced apart in the front-rear direction of the vehicle, and the roadside unit is installed next to or directly above the road, The positioning device according to (2), wherein the roadside device passage determination unit determines whether or not the roadside device has been passed by detecting a reversal of the sign of the path difference before and after the passage of the roadside device.

[0116] (6) When the plurality of antennas are mounted spaced apart in the vehicle width direction, and the roadside unit is installed next to the road, The positioning device according to (2), wherein the roadside device passage determination unit determines whether or not the roadside device has been passed by detecting that the path difference is maximum when the roadside device has passed.

[0117] (7) The positioning device according to any one of (1) to (6), wherein the positioning calculation unit calculates the position of the roadside unit from the position of the antenna and the path difference by hyperbolic positioning or direction estimation.

[0118] (8) Computers Based on the difference in arrival time when signals transmitted from a roadside unit installed on the roadside are received by multiple antennas installed on the vehicle, the path difference from the roadside unit to each of the antennas is measured. The relative position changes of each antenna due to the movement of the vehicle during the measurement time of the aforementioned path difference are calculated. A positioning method that performs a process of calculating the position of the roadside unit based on the path difference measured at at least two different locations and the relative position change of the vehicle between the different locations.

[0119] (9) On the computer, Based on the difference in arrival time when signals transmitted from a roadside unit installed on the roadside are received by multiple antennas installed on the vehicle, the path difference from the roadside unit to each of the antennas is measured. The relative position changes of each antenna due to the movement of the vehicle during the measurement time of the aforementioned path difference are calculated. A positioning program for performing a process to calculate the position of the roadside unit based on the path difference measured at at least two different locations and the relative position change of the vehicle between the different locations. [Explanation of symbols]

[0120] 10 Positioning device 12 vehicles 14 Antennas 14A Antenna A 14B Antenna B 16 Wheel speed sensor 18 Roadside unit 20 Path difference measurement unit 22 Relative position calculation unit 24 Positioning Calculation Unit 26 Roadside machine passage determination section 28 Path Difference Selection Section 30 Vehicle motion estimation unit

Claims

1. Multiple antennas are installed on the vehicle to receive transmission signals from roadside units installed on the roadside, A path difference measuring unit measures the path difference from the roadside unit to each of the antennas based on the difference in arrival time when the transmitted signal from the roadside unit is received by each of the antennas, A relative position calculation unit calculates the relative position change of each antenna due to the movement of the vehicle during the measurement time of the path difference, A positioning calculation unit calculates the position of the roadside unit based on the path difference measured by the path difference measurement unit at at least two different locations and the relative position change of the vehicle between the different locations calculated by the relative position calculation unit. A positioning device equipped with the following features.

2. The system further includes a roadside device passage determination unit that determines whether or not the vehicle has passed the roadside device. The positioning device according to claim 1, wherein the positioning calculation unit determines the position of the roadside unit using the path difference measured at least once before and once after the vehicle passes the roadside unit.

3. The system further includes a path difference selection unit that selects from among the path differences measured by the path difference measurement unit at multiple locations a combination of at least two path differences in which the measured path differences and the hyperbolas obtained from the position of the vehicle intersect at an angle closer to a right angle. The positioning device according to claim 1, wherein the positioning calculation unit calculates the position of the roadside unit using the set of path differences selected by the path difference selection unit.

4. The positioning device according to claim 1, wherein the relative position calculation unit determines the change in the position of the vehicle during the measurement time, including the turning motion of the vehicle, from the vehicle speed and the change in the direction of the vehicle.

5. When the plurality of antennas are mounted spaced apart in the front-rear direction of the vehicle, and the roadside unit is installed next to or directly above the road, The positioning device according to claim 2, wherein the roadside device passage determination unit determines whether or not the roadside device has been passed by detecting a reversal of the sign of the path difference before and after the passage of the roadside device.

6. When the plurality of antennas are mounted spaced apart in the vehicle width direction, and the roadside unit is installed next to the road, The positioning device according to claim 2, wherein the roadside device passage determination unit determines whether or not the roadside device has been passed by detecting that the path difference is maximum when the roadside device has been passed.

7. The positioning device according to claim 1, wherein the positioning calculation unit calculates the position of the roadside unit from the position of the antenna and the path difference by hyperbolic positioning or direction estimation.

8. Computers Based on the difference in arrival time when signals transmitted from a roadside unit installed on the roadside are received by multiple antennas installed on the vehicle, the path difference from the roadside unit to each of the antennas is measured. The relative position changes of each antenna due to the movement of the vehicle during the measurement time of the aforementioned path difference are calculated. A positioning method that performs a process of calculating the position of the roadside unit based on the path difference measured at at least two different locations and the relative position change of the vehicle between the different locations.

9. On the computer, Based on the difference in arrival time when signals transmitted from a roadside unit installed on the roadside are received by multiple antennas installed on the vehicle, the path difference from the roadside unit to each of the antennas is measured. The relative position changes of each antenna due to the movement of the vehicle during the measurement time of the aforementioned path difference are calculated. A positioning program for performing a process to calculate the position of the roadside unit based on the path difference measured at at least two different locations and the relative position change of the vehicle between the different locations.

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