Estimation device, program, and system

Abstract

Achieves more accurate position estimation based on TDOA. [Solution] An estimation device is provided, comprising: an estimation unit that estimates the position of a transmitter based on the difference in arrival times of radio waves transmitted by the transmitter in accordance with a predetermined standard to each of a plurality of receivers, wherein the estimation unit prioritizes the obtained plurality of arrival time differences based on predetermined priority conditions, estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority, and the predetermined priority conditions include at least one of the following: the arrival time difference is smaller or the arrival time is earlier.

Description

[Technical Field]

[0001] The present invention relates to an estimation device, program, and system. [Background technology]

[0002] In recent years, as disclosed in Patent Document 1, for example, a technology has been developed to estimate the location of a transmitter based on TDOA (Time Difference Of Arrival). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-146473 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, since TDOA obtained in real-world environments contains noise, the error range in TDOA-based position estimation increases or decreases depending on the combination of TDOA used.

[0005] Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to realize more accurate position estimation based on TDOA. [Means for solving the problem]

[0006] To solve the above problems, according to one aspect of the present invention, an estimation device is provided comprising: an estimation unit that estimates the position of a transmitter based on the difference in arrival times of radio waves transmitted by the transmitter in accordance with a predetermined standard to each of a plurality of receivers, wherein the estimation unit prioritizes the obtained plurality of arrival time differences based on predetermined priority conditions, estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority, and the predetermined priority conditions include at least one of the following: the arrival time difference is smaller or the arrival time is earlier.

[0007] Furthermore, in order to solve the above problems, according to another aspect of the present invention, a program is provided that enables a computer to implement an estimation function that estimates the position of a transmitter based on the difference in arrival times of radio waves compliant with a predetermined standard transmitted by the transmitter to each of a plurality of receivers, the estimation function prioritizes the acquired plurality of arrival time differences based on predetermined priority conditions, estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority, and the predetermined priority conditions include at least one of the following: the arrival time difference is smaller or the arrival time is earlier.

[0008] Furthermore, in order to solve the above problems, according to another aspect of the present invention, a system is provided comprising: a transmitter that emits radio waves conforming to a predetermined standard; at least three or more receivers that receive the radio waves conforming to the predetermined standard emitted by the transmitter; and an estimation device that estimates the position of the transmitter based on the difference in arrival times when the radio waves conforming to the predetermined standard emitted by the transmitter reach each of the at least three or more receivers, wherein the estimation device prioritizes the acquired differences in arrival times based on predetermined priority conditions, estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority, and the predetermined priority conditions include at least one of the following: the difference in arrival time is smaller, or the arrival time is earlier. [Effects of the Invention]

[0009] As described above, the present invention makes it possible to achieve more accurate position estimation based on TDOA. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram illustrates the overview of position estimation based on TDOA. [Figure 2] This diagram illustrates the overview of position estimation based on TDOA. [Figure 3] This figure shows examples of hyperbolas obtained from the calculation results of equations (1) and (4) for receivers 20A and 20B at a certain position on a two-dimensional plane. [Figure 4] This diagram illustrates an example of position estimation of the transmitter 10 based on hyperbolas for each combination of the three receivers 20A to 20C. [Figure 5] This figure shows an example of the error range for a hyperbola. [Figure 6] This figure shows examples of six hyperbolas obtained from combinations of two of the four receivers 20. [Figure 7] Figure 6 shows two hyperbolas obtained from the combination of [receivers 20A and 20B] and the combination of [receivers 20A and 20C], out of the six hyperbolas illustrated in Figure 6. [Figure 8] Figure 6 shows two hyperbolas obtained from the combination of [receivers 20B and 20C] and the combination of [receivers 20B and 20D], out of the six hyperbolas illustrated in Figure 6. [Figure 9] This figure shows another example of the six hyperbolas obtained from a combination of two of the four receivers 20. [Figure 10] Figure 9 shows two hyperbolas obtained from the combination of [receivers 20A and 20C] and the combination of [receivers 20B and 20D], out of the six hyperbolas illustrated in Figure 9. [Figure 11]It is a diagram showing two hyperbolas respectively obtained from the combinations of [receivers 20A and 20B] and [receivers 20A and 20C] among the six hyperbolas illustrated in FIG. 9. [Figure 12] It is a block diagram showing an example of the functional configuration of system 1 according to an embodiment of the present invention. [Figure 13] It is a flowchart showing an example of the processing flow by server 30 according to the embodiment. [Figure 14] It is a diagram for explaining a predetermined change condition according to the embodiment.

Embodiments of the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0012] Also, in the present specification and drawings, when describing a plurality of components of the same type separately, an alphabet or the like may be appended to the end of the reference numeral. On the other hand, when there is no need to distinguish a plurality of components of the same type, the above alphabet or the like is omitted, and there may be cases where descriptions common to all of the plurality of components of the same type are made.

[0013] <1. Embodiment> <<1.1. Position Estimation Based on TDOA>> First, position estimation based on TDOA will be described.

[0014] FIG. 1 and FIG. 2 are diagrams for explaining the outline of position estimation based on TDOA. [[ID=3s]]

[0015] FIG. 1 shows an example of the positional relationship between transmitter 10 and receivers 20A to 20C on a two-dimensional plane (XY plane).

[0016] Here, the coordinates (X A , YA ) to (X C , Y C ) is known, and the coordinates (X0, Y0) of the transmitter 10 are unknown.

[0017] In this case, the coordinates (X0, Y0) of the transmitter 10 can be calculated based on the distances from the transmitter 10 to each of the receivers 20A to 20C.

[0018] For example, the difference R between the distance from the transmitter 10 to the receiver 20A and the distance to the receiver 20B AB , the difference R between the distance from the transmitter 10 to the receiver 20A and the distance to the receiver 20C AC , and the difference R between the distance from the transmitter 10 to the receiver 20B and the distance to the receiver 20C BC can be obtained by the following mathematical formulas (1) to (3), respectively.

[0019]

Number

[0020] Also, R AB , R<00000**********]]

[0023] In this case, R AB , R AC , R BC ​​​​​​​​​​​​​​​​​​This can be calculated using the following formulas (4) to (6). In formulas (4) to (6) below, C represents the speed of light [m / s].

[0024]

number

[0025] The coordinates (X0, Y0) of transmitter 10 can be estimated from the calculation results of equations (1) to (6). Geometrically, this position estimation is a problem of finding the intersection point of a hyperbola.

[0026] Figure 3 shows an example of a hyperbola obtained from the calculation results of equations (1) and (4) for receivers 20A and 20B at a certain position on a two-dimensional plane.

[0027] Figure 3 illustrates several hyperbolas when the difference between the time when the radio waves transmitted by the transmitter 10 reach receiver 20A and the time when the radio waves reach receiver 20B, i.e., TDOA, is between -60ns and 60ns.

[0028] Figure 3 illustrates several hyperbolas corresponding to the TDOA value, but if the TDOA is uniquely determined for a given combination of two receivers 20, then the hyperbolas associated with that combination are also uniquely determined.

[0029] Figure 4 illustrates an example of position estimation of the transmitter 10 based on hyperbolas for each combination (pair) of the three receivers 20A to 20C.

[0030] Figure 4 illustrates three hyperbolas corresponding to each combination of [receivers 20A and 20B], [receivers 20A and 20C], and [receivers 20B and 20C].

[0031] As in this example, if at least two hyperbolas are obtained, the position of the transmitter 10 can be estimated as the intersection point of at least two hyperbolas. Note that at least three receivers 20 are required to obtain at least two hyperbolas.

[0032] However, the actual TDOA obtained contains noise. Assuming the amount of this noise is constant, the error range of the hyperbola differs depending on the relative positions of the transmitter 10 and the receiver 20.

[0033] Figure 5 shows an example of the error range for a hyperbola.

[0034] Figure 5 shows, with dashed lines, the ranges that each hyperbola can take when TDOA is varied by ±2ns for several hyperbolas exemplified in Figure 3.

[0035] In the example shown in Figure 5, the error is small near the center of the figure, moderate in the upper and lower parts of the figure, and large in the left and right parts of the figure.

[0036] As described above, the error of the hyperbola changes depending on the positional relationship between the transmitter 10 and the receiver 20. Therefore, it is expected that the accuracy of the estimation will be improved by using a hyperbola with a smaller error to estimate the position of the transmitter 10.

[0037] Figure 6 shows examples of six hyperbolas obtained from combinations of two of the four receivers 20.

[0038] The six hyperbolas illustrated in Figure 6 each have different error ranges depending on the relative positions of the transmitter 10 and the receiver 20.

[0039] Figure 7 shows two hyperbolas obtained from the combination of [receivers 20A and 20B] and the combination of [receivers 20A and 20C], respectively, from the six hyperbolas illustrated in Figure 6.

[0040] Figure 7 shows that the error range is relatively large near the intersection of the two hyperbolas.

[0041] On the other hand, Figure 8 shows two hyperbolas obtained from the combination of [receivers 20B and 20C] and the combination of [receivers 20B and 20D], respectively, from the six hyperbolas illustrated in Figure 6.

[0042] The area around the intersection of the two hyperbolas shown in Figure 8 has a smaller error range compared to the case in Figure 7.

[0043] Therefore, in this example, it is expected that estimating the position of the transmitter 10 from the intersection of two hyperbolas obtained from the combination of [receivers 20B and 20C] and [receivers 20B and 20D], as exemplified in Figure 8, will result in a smaller error in the estimation result than estimating the position of the transmitter 10 from the intersection of two hyperbolas obtained from the combination of [receivers 20A and 20C] and [receivers 20A and 20C], as exemplified in Figure 7.

[0044] On the other hand, Figure 9 shows another example of six hyperbolas obtained from a combination of two of the four receivers 20.

[0045] Figure 10 shows two hyperbolas obtained from the combination of [receivers 20A and 20C] and the combination of [receivers 20B and 20D], respectively, from the six hyperbolas illustrated in Figure 9.

[0046] Figure 11 also shows two hyperbolas obtained from the combination of [receivers 20A and 20B] and the combination of [receivers 20A and 20C], respectively, from the six hyperbolas illustrated in Figure 9.

[0047] Comparing Figures 10 and 11, the error range near the intersection of the two hyperbolas is relatively small in both, but the overlapping area of ​​the two hyperbolas in Figure 10 is wide, and multiple intersection points may exist.

[0048] Therefore, in this example, it is expected that estimating the position of the transmitter 10 from the intersection of two hyperbolas obtained from the combination of [receivers 20A and 20B] and [receivers 20A and 20C], as exemplified in Figure 11, will result in a smaller error in the estimation result than estimating the position of the transmitter 10 from the intersection of two hyperbolas obtained from the combination of [receivers 20A and 20B] and [receivers 20A and 20C], as exemplified in Figure 10.

[0049] The technical concept of the present invention was conceived with the above-mentioned points in mind, and aims to achieve more accurate position estimation based on TDOA.

[0050] The following describes in detail an example of the functional configuration of System 1 according to one embodiment of the present invention.

[0051] <<1.2. Example of Functional Configuration>> Figure 12 is a block diagram showing an example of the functional configuration of System 1 according to one embodiment of the present invention.

[0052] The system 1 according to this embodiment may include at least one transmitter 10, a plurality of receivers 20, and a server 30.

[0053] The system 1 according to this embodiment includes, for example, at least three or more receivers 20, namely receivers 20A to 20n.

[0054] Furthermore, in this embodiment, as shown in Figure 12, we illustrate a case where system 1 has one transmitter 10, but system 1 may have multiple transmitters 10. In this case, server 30 may estimate the position of each of the multiple transmitters 10.

[0055] (Transmitter 10) The transmitter 10 includes at least a configuration that emits a certain type of wave. The communication unit 110 is an example of such configuration.

[0056] (Communications Department 110) The communication unit 110 may, for example, have a function to transmit radio waves that conform to a predetermined standard.

[0057] For this purpose, the communication unit 110 may be equipped with an antenna that emits radio waves conforming to a predetermined standard.

[0058] Examples of the specified standards mentioned above include ultra-wideband (UWB) wireless communication standards. However, the specified standards are not limited to such examples, and any standard may be adopted as the specified standard.

[0059] However, the waves emitted by the transmitter 110 (also called transmitted waves) are not limited to radio waves. Transmitted waves may be, for example, sound waves, light waves, etc.

[0060] Furthermore, the transmitted waves do not necessarily have to conform to the specified standards. Even if the transmitted waves do not conform to the specified standards, for example, by comparing the waveform patterns of the received waves in the server 30, it is possible to identify that the received waves received by each receiver 20 originate from the same transmitter 10 (source) and to estimate the location of the transmitter 10.

[0061] (Receiver 20) Each of the three or more receivers 20 is equipped with at least one configuration for receiving a transmitted wave. The communication unit 210 is an example of such configuration.

[0062] (Communications Department 210) The communication unit 210 may, for example, receive radio waves transmitted by the transmitter 10 that conform to a predetermined standard.

[0063] For this purpose, the communication unit 210 may be equipped with an antenna that receives radio waves conforming to a predetermined standard.

[0064] Furthermore, the communication unit 210 transmits to the server 30 information regarding the time when it received radio waves compliant with a predetermined standard transmitted by the transmitter 10 (the time when the radio waves compliant with a predetermined standard transmitted by the transmitter 10 reached the receiver 20: arrival time).

[0065] (Server 30) Server 30 is an example of an estimation device according to this embodiment.

[0066] The server 30 includes at least a communication unit 310 and an estimation unit 320.

[0067] (Communications Department 310) The communication unit 310 receives information regarding the arrival time from each of the multiple receivers 20.

[0068] The communication between the communication unit 310 and the receiver 20 may be wireless or wired.

[0069] (Estimation part 320) The estimation unit 320 estimates the position of the transmitter 10 based on the difference in arrival times (TDOA) of the radio waves transmitted by the transmitter 10, which conform to a predetermined standard, reaching each of the multiple receivers 20.

[0070] The estimation unit 320 calculates the TDOA for all possible combinations (pairs) of the multiple receivers 20.

[0071] Furthermore, as will be described later, the estimation unit 320 is characterized by prioritizing the calculated TDOA based on predetermined priority conditions and estimating the position of the transmitter 10 using a predetermined number of TDOA with higher priority.

[0072] The functions of the estimation unit 320 are realized through the cooperation of various processors and memory.

[0073] Details of the functions of the estimation unit 320 will be described later.

[0074] The above describes an example of the functional configuration of System 1 according to this embodiment. Note that the above functional configuration described with reference to Figure 12 is merely an example, and the functional configuration of System 1 according to this embodiment is not limited to this example.

[0075] For example, the transmitter 10, receiver 20, and server 30 may further have configurations other than those described above.

[0076] As an example, the server 30 may further include a display unit, an operation reception unit, a storage unit, and the like.

[0077] Furthermore, the above example illustrates a functional configuration when server 30 operates as an estimation device, but this is also just one example.

[0078] The estimation device may be one of the receivers 20 or the transmitter 10.

[0079] In this case, any of the receivers 20 acting as estimation devices, or the transmitter 10, can estimate the position of the transmitter 10 by receiving information regarding the arrival times of multiple receivers 20.

[0080] The functional configuration of System 1 according to this embodiment can be flexibly modified according to specifications, operation, etc.

[0081] <<1.3. Processing Flow>> Next, the processing flow by the server 30 according to this embodiment will be described in detail.

[0082] Figure 13 is a flowchart showing an example of the processing flow by the server 30 according to this embodiment.

[0083] In the example shown in Figure 13, first, the communication unit 310 receives information regarding the arrival time from each of the multiple receivers 20 (S101).

[0084] Next, the estimation unit 320 calculates the TDOA for all possible combinations (pairs) of receivers 20 based on the information regarding arrival times received by the communication unit 310 in step S101 (S102).

[0085] Next, the estimation unit 320 excludes TDOAs that meet predetermined exclusion conditions (S103).

[0086] The above-mentioned exclusion conditions may include the condition that the distance between the pair of receivers 20 is less than a threshold (for example, about 1 m).

[0087] Furthermore, the above-mentioned exclusion conditions may include the condition that at least one of the arrival times used in the calculation of TDOA is 0.

[0088] According to the predetermined exclusion conditions described above, the accuracy of position estimation can be improved by pre-excluding TDOAs related to receivers 20 whose arrival time could not be correctly obtained due to some error, and TDOAs that are too close together to be suitable for position estimation of transmitters 10.

[0089] Next, the estimation unit 320 prioritizes the multiple TDOAs calculated in step S102, excluding those excluded in step S103, based on predetermined priority conditions (S104).

[0090] The above-mentioned priority conditions may include at least one of the following: a lower TDOA or an earlier arrival time.

[0091] According to the predetermined priority conditions described above, the priority of TDOA, which has a small hyperbolic error range, can be increased, making it possible to improve the position estimation accuracy of the transmitter 10.

[0092] Next, the estimation unit 320 changes the priority order determined in step S104 based on predetermined modification conditions (S105).

[0093] The above-mentioned specified modification conditions may include lowering the priority of a corresponding TDOA if the angle formed on a two-dimensional plane between the two combinations of receivers 20 used to calculate the TDOA is smaller than a threshold (for example, 10°).

[0094] Figure 14 is a diagram illustrating predetermined modification conditions according to this embodiment.

[0095] Figure 14 shows thick lines connecting the pairs of receivers 20 [receivers 20A and 20C] and [receivers 20B and 20D] associated with each hyperbola, with respect to the two hyperbolas with a wide overlapping region as illustrated in Figure 10.

[0096] In this example, the two thick lines are parallel, meaning that the angle between the two combinations of receivers 20 used to calculate the TDOA on the two-dimensional plane is 0°.

[0097] Therefore, according to the predetermined modification conditions described above, the priority of the TDOA related to two hyperbolas with a wide overlapping area can be lowered, making it possible to improve the position estimation accuracy of the transmitter 10.

[0098] Furthermore, the specified modification conditions may also include lowering the priority of TDOAs with later arrival times used in the calculation of TDOA. Under such conditions, further improvements in estimation accuracy can be expected.

[0099] Next, the estimation unit 320 estimates the position of the transmitter 10 using a predetermined number of TDOAs with high priority (S106).

[0100] In order to estimate the position of the transmitter 10, at least two TDOAs are required, but the predetermined number may be three or more (for example, six). If the predetermined number is set to three or more, the estimation unit 320 may perform multiple position estimations for possible pairs of TDOAs and take the average of the estimation results.

[0101] <2. Supplement> Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0102] Furthermore, the series of processes performed by each device described herein may be implemented by a program stored in a non-transitory computer-readable storage medium. Each program is, for example, loaded into RAM when executed by a computer and executed by a processor such as a CPU. The storage medium may be, for example, a magnetic disk, an optical disk, a magneto-optical disk, or flash memory. Alternatively, the program may be distributed without using a storage medium, for example, via a network. [Explanation of symbols]

[0103] 1: System, 10: Transmitter, 110: Communication Unit, 20: Receiver, 210: Communication Unit, 30: Server, 310: Communication Unit, 320: Estimation Unit

Claims

1. An estimation unit that estimates the position of the transmitter based on the difference in arrival times of radio waves transmitted by the transmitter, which conform to a predetermined standard, to each of a plurality of receivers. Equipped with, The estimation unit prioritizes the multiple differences in arrival times obtained based on predetermined priority conditions, and estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority. The aforementioned predetermined priority conditions include at least one of the following: the difference in arrival times is smaller, or the arrival time is earlier. Estimation device.

2. The estimation unit changes the priority order of the multiple arrival time differences obtained based on predetermined modification conditions, and estimates the position of the transmitter using a predetermined number of arrival time differences with higher priority. The aforementioned predetermined modification condition includes lowering the priority of the corresponding arrival time difference if the angle formed on a two-dimensional plane between the two receivers used to obtain the arrival time difference is smaller than a threshold. The estimation device according to claim 1.

3. The predetermined modification condition further includes lowering the priority of the later arrival time differences used to obtain the arrival time differences, The estimation device according to claim 2.

4. The estimation unit excludes the differences in arrival times that fall under predetermined exclusion conditions, and then prioritizes the obtained differences in arrival times based on predetermined priority conditions. The predetermined exclusion condition includes the fact that the distance between the two receivers used to obtain the difference in arrival times is less than a threshold. The estimation device according to claim 1.

5. The aforementioned predetermined exclusion condition further includes that at least one of the arrival times used to obtain the difference in arrival times is 0. The estimation device according to claim 4.

6. The aforementioned specified standard is an ultra-wideband wireless communication standard. An estimation device according to any one of claims 1 to 5.

7. On the computer, An estimation function that estimates the position of a transmitter based on the difference in arrival times of radio waves transmitted by the transmitter, which conform to a predetermined standard, to each of several receivers. To make it happen, The estimation function prioritizes the multiple arrival time differences obtained based on predetermined priority conditions, and estimates the position of the transmitter using the predetermined number of arrival time differences with higher priority. The aforementioned predetermined priority conditions include at least one of the following: the difference in arrival times is smaller, or the arrival time is earlier. program.

8. A transmitter that emits radio waves conforming to a specified standard, At least three or more receivers that receive radio waves compliant with the predetermined standard transmitted by the transmitter, An estimation device that estimates the position of the transmitter based on the difference in arrival times of radio waves compliant with a predetermined standard transmitted by the transmitter to each of at least three or more receivers, Equipped with, The estimation device prioritizes the multiple arrival time differences obtained based on predetermined priority conditions, and estimates the position of the transmitter using the predetermined number of arrival time differences with higher priority. The aforementioned predetermined priority conditions include at least one of the following: the difference in arrival times is smaller, or the arrival time is earlier. system.

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