JP6804806B2 - Positioning accuracy information calculation device and positioning accuracy information calculation method - Google Patents

Description

The present invention relates to a positioning accuracy information calculation device and a positioning accuracy information calculation method.

In recent years, in addition to GPS (Global Positioning System), various navigation satellites such as GRONASS (Global Navigation Satellite System) and QZSS (Quasi-Zenith Satellite System) have been launched, and the use of position information is widespread. Positioning using navigation satellites enables positioning by securing four or more satellites, but the number of visible satellites decreases due to the shielding of structures such as buildings, and the effects of multipath and diffraction by structures such as buildings. As a result, the positioning accuracy may deteriorate to the order of several tens of meters.

Non-Patent Document 1 discloses that the number of visible satellites, the rate of precision reduction (DOP), and the error distribution are simulated by using accurate orbit information of satellites and a three-dimensional digital map. ..

Non-Patent Document 2 identifies structures that hinder the reception of satellite signals from the sky image data of the antenna installation position taken with a fisheye lens, and estimates the reception characteristics of the satellite signals together with the orbit information of the navigation satellite. Therefore, we are studying a method to improve the efficiency of GPS antenna installation work.

Tomohiro HAKAMATA, "Development of a Simulation System to Delineate Availability of GNSS with3-D Digital Map", Proceedings of the 23rd Asian Conference on Remote Sensing, 2002, 2002 Keisuke Nishi, Masashi Yoshida, Takashi Hirose, "Proposal of satellite signal reception characteristic estimation method to improve efficiency of GPS antenna installation work", Shingaku Giho 115 (155), 23-28, 2015-07-24

Navigation satellites are expected to have more opportunities to be used in various fields such as autonomous driving and social infrastructure management in the future. When navigation satellites are used more frequently in this way, depending on the content of services using navigation satellites, areas that are advantageous / disadvantageous for satellite positioning, positioning accuracy predicted at each time zone, etc. It is possible that information is needed. In addition, such information on positioning accuracy can also be used as basic data for improving the satellite radio wave shielding environment.

However, providing positioning accuracy information for each time zone for each of the geographically subdivided areas has an extremely large computational load.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a positioning accuracy information calculation device and a positioning accuracy information calculation method capable of outputting positioning accuracy information with a further reduced processing load. To do.

In order to achieve the above object, the positioning accuracy information calculation device according to the present invention uses one mesh point as a representative point among a plurality of mesh points representing the positions of the plurality of regions, and includes the representative point. A representative point determination unit that defines the plurality of mesh points in the vicinity of the representative point as a plurality of neighborhood points, and acquisition of position information of the representative point and satellite orbit information are obtained to obtain the target time at the representative point. A sky image is acquired for each of the satellite coordinate calculation unit that calculates the elevation angle of the satellite position and the plurality of neighborhood points, an open space is identified from the sky image, and a circle centered on the zenith is based on the open space. The number of visible satellites for each of the plurality of neighboring points is calculated based on the approximate open space calculation unit for calculating the approximate open space of the above, the elevation angle of the representative point, and the approximate open space of each of the plurality of neighboring points. It is characterized by including a visible satellite number calculation unit.

In order to achieve the above object, the positioning accuracy information calculation method according to the present invention includes one mesh point as a representative point among a plurality of mesh points representing the positions of a plurality of regions, and includes the representative point. The plurality of mesh points in the vicinity of the representative point are defined as a plurality of neighborhood points, the position information of the representative point is acquired, the orbit information of the satellite is acquired, and the elevation angle of the satellite position at the target time at the representative point is determined. Calculate, acquire a sky image for each of the plurality of neighborhood points, identify an open space from the sky image, calculate a circular approximate open space centered on the zenith based on the open space, and calculate the representative. It is characterized in that the number of visible satellites of each of the plurality of neighborhood points is calculated based on the elevation angle of the point and the approximate open space of each of the plurality of neighborhood points.

According to the present invention, the processing load can be further reduced and the positioning accuracy information of the navigation satellite can be output.

Schematic diagram showing the configuration of the positioning accuracy information calculation system according to this embodiment Diagram for explaining representative points and neighboring points Diagram explaining the elevation angle of the satellite position Diagram for explaining an example of acquiring a sky image Flowchart showing an example of positioning accuracy information calculation processing Flowchart showing the satellite coordinate calculation process in detail Flow chart showing the approximate open space calculation process in detail The figure which shows the example of the image which made it easy to distinguish open space and closed space A diagram illustrating an example of an approximate open space A diagram illustrating an example of an approximate open space Flowchart showing the number of visible satellites calculation process in detail A diagram illustrating an example of a method for determining whether or not a satellite is a visible satellite. Diagram showing an example of an image of the target area showing the number of visible satellites

The positioning accuracy information calculation system 1 according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the configuration of the positioning accuracy information calculation system 1 according to the present embodiment. The positioning accuracy information calculation system 1 is composed of a positioning accuracy information calculation device 10, a satellite information storage device 21, and a sky image acquisition device 22. Each of the positioning accuracy information calculation device 10, the satellite information storage device 21, and the sky image acquisition device 22 is mainly composed of a semiconductor device, and has volatile storage such as a CPU (Central Processing Unit) and a RAM (Random Access Memory). It may be configured as a so-called information processing device having a device, a non-volatile storage device such as a hard disk or a flash memory, and a communication interface for making a connection for communication with the outside.

In the present embodiment, it is assumed that each of these devices is connected to the communication network 31. However, either or both of the satellite information storage device 21 and the sky image acquisition device 22 may be realized by the functions in the positioning accuracy information calculation device 10. The communication network 31 can be a communication network 31 that makes a communication connection by using a TCP (Transmission Control Protocol) / IP (Internet Protocol) protocol such as LAN (Local Area Network) or the Internet. The communication network 31 can be a communication network 31 using either or both of wired and wireless.

The satellite information storage device 21 can store the orbit information of a plurality of satellites 61 among various navigation satellites such as GPS, GRONASS, and QZSS. The satellite information storage device 21 may be configured as a server device that can be accessed via the communication network 31. When the orbit information is acquired from the satellite signal of the navigation satellite, the navigation satellite may be the satellite information storage device 21.

When a sky image at a position indicated by a certain position information is requested, the sky image acquisition device 22 transmits the sky image at that position. Here, the sky image includes, for example, an image in a plan view centered on the zenith, an image obtained by taking a picture of the sky using a fisheye lens, or the like. Here, the sky image acquisition device 22 may have a function of generating a sky image based on, for example, three-dimensional map information or a landscape image taken by an in-vehicle camera or the like. The sky image acquisition device 22 may be configured as a server device that can be accessed via the communication network 31.

The positioning accuracy information calculation device 10 includes a representative point determination unit 11, a satellite coordinate calculation unit 12, an approximate open space calculation unit 13, a visible satellite number calculation unit 14, and a visible satellite number display unit 15. .. The representative point determination unit 11 has a plurality of mesh points 52 representing the respective positions of the plurality of regions 54, one mesh point 52 as the representative point 51, including the representative point 51, and a plurality of mesh points in the vicinity of the representative point 51. The mesh point 52 is defined as a plurality of neighborhood points 55. Here, the representative point determination unit 11 may further divide the target area into a mesh shape, and if the groups of the neighborhood points 55 are different, determine different representative points 51.

FIG. 2 is a diagram for explaining a representative point 51 and a vicinity point 55. FIG. 2 shows two neighborhood point regions 50, each of which is divided into a plurality of regions 54 by a mesh 53. Each region 54 has a mesh point 52 that represents its position. The representative point determination unit 11 determines one of the plurality of mesh points 52 included in the neighborhood point region 50 as the representative point 51, and determines the mesh point 52 included in the neighborhood point region 50 including the representative point 51. Is determined as the neighborhood point 55. Here, the mesh point 52 can be the center of gravity when each region 54 is a two-dimensional plane. Further, the representative point 51 can be a mesh point 52 of the region 54 including the center of gravity in the plurality of regions 54 (neighborhood point regions 50) related to the plurality of neighborhood points 55. The representative point 51 and the neighborhood point 55 shown in FIG. 2 are examples, and may be defined as a plurality of neighborhood points 55 including the representative point 51 and the representative point 51 by another method.

The satellite coordinate calculation unit 12 acquires the position information of the representative point 51 and, for example, the orbit information of the satellite 61 from the satellite information storage device 21, and calculates the elevation angle θ of the satellite position at the target time at the representative point 51. FIG. 3 is a diagram illustrating an elevation angle θ of the satellite position. As shown in this figure, the elevation angle θ is the angle from the horizontal plane when looking up at the satellite 61 at the representative point 51. Since the positioning satellite orbits at an altitude of about 20,000 km, the distance between the representative point 51 and the other neighboring points 55 is negligible. Therefore, the elevation angle θ of each satellite 61 is substantially the same at the representative point 51 and the neighborhood point 55 near the representative point 51, and the elevation angle θ is calculated by using the elevation angle θ of the representative point 51 also at the neighborhood point 55. Therefore, the elevation angle θ at the neighborhood point 55 is not calculated. As a result, the processing load of calculation can be further reduced.

Specifically, for example, an equation representing the satellite orbit in the ECEF (Earth Centered Earth Fixed) coordinate system is derived from the information for identifying the satellite orbit such as a given satellite orbit element. Then, the process of calculating the solution of this equation and converting it into the coordinate system centered on the observation point is repeated at each time (eg, 24 hours at 1-minute intervals). As a result, the coordinates of each satellite are output in units of time. However, in the coordinate system centered on the observation point, since only the elevation angle θ is used thereafter, only the elevation angle θ is calculated. In the case of normal satellite coordinate calculation, when the azimuth angle is calculated in addition to the elevation angle θ, the azimuth angle is not calculated, so that the calculation processing load can be further reduced.

The approximate open space calculation unit 13 acquires a sky image for each of the plurality of neighborhood points 55, identifies the open space 65 from the sky image, and based on the open space 65, a circular approximate open space 67 centered on the zenith. Is calculated. The sky image, the open space 65, and the approximate open space 67 will be described in detail when the flowchart of FIG. 5 is described. The number of visible satellites calculation unit 14 calculates the number of visible satellites of each of the plurality of neighborhood points 55 based on the elevation angle θ of the representative point 51 and the approximate open space 67 of each of the plurality of neighborhood points 55. The calculation of the number of visible satellites will be described in detail when the flowchart of FIG. 5 is described. The visible satellite number display unit 15 displays an image showing the number of visible satellites in each of the plurality of regions 54. Here, the positioning accuracy information calculation device 10 may be configured not to have the visible satellite number display unit 15.

FIG. 4 is a diagram for explaining an example of acquiring a sky image by the sky image acquisition device 22. As shown in this figure, the sky image acquisition device 22, the three-dimensional map information storage device 23, the in-vehicle camera image storage device 24, and the sky capture image storage device 25 are connected to the communication network 32. Here, the communication network 32 may be the same network as the communication network 31, and any or all of the three-dimensional map information storage device 23, the in-vehicle camera image storage device 24, and the sky-captured image storage device 25 may be used. It may be configured as a server device accessed via the communication network 32.

Here, the three-dimensional map information storage device 23 stores three-dimensional map information including information on structures such as buildings. The sky image acquisition device 22 can acquire three-dimensional map information from the three-dimensional map information storage device 23, and can generate a sky image at the position indicated by the position information based on the acquired three-dimensional map information.

The in-vehicle camera image storage device 24 stores and stores images taken by an in-vehicle camera or the like. The sky image acquisition device 22 acquires an image taken by an in-vehicle camera or the like from the in-vehicle camera image storage device 24 (for example, an image in which there is a road in the center and buildings are shown on both sides), and the sky at the position indicated by the position information. Images can be generated. Since the image taken by the in-vehicle camera or the like is not an image at all positions, it may not be possible to generate a three-dimensional image depending on the position information. However, since the sky image itself or an image close to the sky image may be stored together, if the image taken by the in-vehicle camera or the like can be used, the sky image is not generated from the three-dimensional map information. However, it may be possible to reduce the processing load.

The sky photographed image storage device 25 stores the sky image directly photographed. The sky image acquisition device 22 can acquire a sky image from the sky capture image storage device 25. If there is a sky image taken directly at the position indicated by a certain position information, it is considered that there is less than if the image taken by an in-vehicle camera or the like is available, but the sky image exists at the position related to the position information. In that case, since it can be used as a sky image almost as it is, the processing load can be reduced.

The above-mentioned three-dimensional map information, image information taken by an in-vehicle camera, etc., and sky image information taken directly have differences in update frequency, cost, accuracy, and coverage area, and the positioning environment is grasped and evaluated. The appropriate one depends on the requirements for creating the information for. Approximate open space calculator 13, an image generated from the three-dimensional map information, image generated from an image of the vehicle-mounted cameras, and what is available to any of the captured image the sky, from sky image acquisition apparatus 22 It may be acquired. Further, the approximate open space calculation unit 13 may acquire the latest sky image from the sky image acquisition device 22 when a plurality of sky images can be acquired.

In FIG. 4, the three-dimensional map information storage device 23, the in-vehicle camera image storage device 24, and the sky-captured image storage device 25 are connected to the sky image acquisition device 22 via the communication network 32. Any or all of the original map information storage device 23, the vehicle-mounted camera image storage device 24, and the sky-captured image storage device 25 may be realized by the functions in the sky image acquisition device 22.

FIG. 5 is a flowchart showing an example of the positioning accuracy information calculation process S1 by the positioning accuracy information calculation device 10. As shown in this flowchart, the representative point determination unit 11 of the positioning accuracy information calculation device 10 represents one mesh point 52 among the plurality of mesh points 52 representing the respective positions of the plurality of regions 54 in step S10. A point 51 is defined, and a plurality of mesh points 52 including the representative point 51 and in the vicinity of the representative point 51 are defined as a plurality of neighborhood points 55. Here, in step S10, the representative point determination unit 11 may further divide the target area into a mesh shape, and if the groups of the neighborhood points 55 are different, determine different representative points 51. The example of the representative point 51 and the neighborhood point 55 is the same as that described with reference to FIG.

Next, in step S20, when a plurality of representative points 51 are determined in step S10, the unselected representative points 51 are selected, and in step S30, the satellite coordinate calculation unit 12 satellites the selected representative points 51. The coordinate calculation process S30 is performed. FIG. 6 is a flowchart showing the satellite coordinate calculation process S30 in detail. As shown in this flowchart, in the satellite coordinate calculation process S30, the position information of the selected representative point 51 is acquired in step S31. The position information can be latitude / longitude information at the representative point 51. Next, in step S32, the orbit information of the satellite 61 is acquired from, for example, the satellite information storage device 21. In step S33, the elevation angle θ of the satellite position at the target time at the representative point 51 is calculated. The elevation angle θ is as described with reference to FIG. Here, the elevation angle θ can be calculated for each of the plurality of satellites 61.

Returning to FIG. 5, when the satellite coordinate calculation process S30 is completed, the unselected neighborhood point 55 is selected in step S40. The neighborhood point 55 here also includes the representative point 51. When the neighborhood point 55 is selected, the approximate open space calculation unit 13 subsequently performs the approximate open space calculation process S50. FIG. 7 is a flowchart showing the approximate open space calculation process S50 in detail. As shown in this flowchart, in the approximate open space calculation process S50, in step S51, sky images are acquired from, for example, the sky image acquisition device 22 for each of the neighborhood points 55. As described with reference to FIG. 4, the sky image acquisition device 22 includes information on the three-dimensional map information storage device 23, the in-vehicle camera image storage device 24, and the sky-captured image storage device 25, and other information capable of generating sky images. The sky image can be acquired or generated based on the above.

Next, in step S52, the approximate open space calculation unit 13 identifies the open space 65. Here, the open space 65 is a region in which the satellite 61 is visible in the sky image, and the closed space 66 is a region in which the satellite 61 is invisible in the sky image due to shielding of a structure such as a building. FIG. 8 is an example of an image obtained by processing the sky image to make it easier to distinguish between the open space 65 and the closed space 66. For the image processing, for example, binarization processing, edge extraction processing, and the like can be used. By such processing, the open space 65 and the closed space 66 can be distinguished.

In step S53, the approximate open space calculation unit 13 calculates a circular approximate open space 67 centered on the zenith based on the open space 65. The approximate open space 67 can be calculated, for example, by calculating the elevation angle α that maximizes the area of concentric circles centered on the zenith within the open space 65 on the acquired sky image. The approximate open space 67 can be a concentric region of the calculated elevation angle α. Here, the elevation angle α at the observation point may be output as a value representing the approximate open space 67. As an example of the calculation method of the elevation angle α, first, assuming a rectangle on the sky image, the circumference of the rectangle is scanned to find the point of the structure having the minimum distance from the center of the image. Here, if there is a point of the structure on the circumference, the same scan is performed on the inner rectangle, and if there is no point of the structure on the circumference, the same scan is performed on the outer rectangle. By repeating this, the elevation angle α may be obtained.

FIG. 9 is a diagram for explaining an example of the approximate open space 67. As shown in this figure, the approximate open space 67 has a circular shape centered on the zenith, and may not include, for example, the closed space 66. FIG. 10 is a diagram for explaining another example of the approximate open space 67. As shown in this figure, the approximate open space 67 has a circular shape centered on the zenith, and can include, for example, the closed space 66 as a part within 5%.

Returning to FIG. 5, when the approximate open space calculation process S50 is completed, the visible satellite number calculation unit 14 performs the visible satellite number calculation process S60. FIG. 11 is a flowchart showing the visible satellite number calculation process S60 in detail. As shown in this flowchart, in the visible satellite number calculation process S60, the unselected satellite 61 is selected from the satellites 61 for which the elevation angle θ has been calculated in step S61. Next, it is determined whether the satellite 61 selected in step S62 is a visible satellite. FIG. 12 is a diagram for explaining an example of a method for determining whether or not the satellite is a visible satellite. As shown in this figure, for example, it is visible by comparing the elevation angle α formed by the horizontal plane and the conical shape formed by the approximate open space 67 with the selected neighborhood point 55 as the apex and the elevation angle θ of the selected satellite 61. It may be determined whether it is a satellite. In the example of FIG. 12, since the elevation angle θa of the satellite 61a is larger than the angle α, the satellite 61a is determined to be visible. On the other hand, since the elevation angle θb of the satellite 61b is smaller than the angle α, the satellite 61b is determined to be invisible. In this way, the visible / invisible determination is based on only the one-dimensional elevation angle information, instead of the conventional two-dimensional information, so the calculation processing load can be further reduced. ..

Returning to FIG. 11, when it is determined as a visible satellite in step S62, 1 is added to the number of visible satellites in step S63, and the process proceeds to step S64. On the other hand, if it is not determined as a visible satellite in step S62, the process proceeds to step S64. In step S64, it is determined whether or not all the satellites 61 have been selected, and if there are satellites 61 that have not been selected yet, the process returns to step S61 and the process is repeated. When all the satellites 61 are selected, the visible satellite number calculation process S60 is terminated.

Returning to FIG. 5, when the visible satellite number calculation process S60 is completed, it is determined in step S70 whether or not all the neighborhood points 55 have been selected. If there is a neighborhood point 55 that has not been selected yet, the process returns to step S40 and the process is repeated. Here, with respect to the satellite coordinates (elevation angle θ) of each satellite 61, since the processing of the number of neighboring points 55 is not repeated, the processing load of the calculation can be further reduced. When all the neighborhood points 55 are selected, the process proceeds to step S80, and it is determined whether or not all the representative points 51 have been selected. If there is a representative point 51 that has not been selected yet, the process returns to step S20 and the process is repeated. When all the representative points 51 are selected, the process proceeds to the visible satellite number display process S90.

In the visible satellite number display processing S90, for example, for a target area composed of a plurality of neighborhood point regions 50, an image of the target area representing the number of visible satellites in each of the plurality of regions 54 may be displayed. As a result, the positioning accuracy information in the target area can be visually recognized. FIG. 13 is a diagram showing an example of an image of the target area showing the number of visible satellites. Positioning accuracy information can be further visually recognized by displaying the plurality of regions 54 in different colors according to the number of visible satellites. Here, the visible satellite number display process S70 may not be performed, or may be another mode displayed as a list or the like.

As described above, the positioning accuracy information calculation device 10 of the present embodiment uses only the elevation angle θ of each satellite 61, and determines whether or not it is a visible satellite only by whether or not it is included in the approximate open space 67. Therefore, it is not necessary to calculate the azimuth angle, and the processing load can be reduced.

Further, since the satellite coordinates (for example, elevation angle θ) of each satellite 61 hardly change at the representative point 51 and the neighborhood point 55, the positioning accuracy information calculation device 10 of the present embodiment has the neighborhood point 55 excluding the representative point 51. Since the calculation of the satellite coordinates of the above is not repeated and the satellite coordinates of the representative point 51 are used, the processing load of the calculation can be further reduced.

Further, regarding the determination of the number of satellites as visible / invisible, in the positioning accuracy information calculation device 10 of the present embodiment, the conventional two-dimensional information for determining visible / invisible is limited to the one-dimensional elevation angle information. Since it is determined by, the processing load of calculation can be further reduced.

Further, in the positioning accuracy information calculation device 10 of the present embodiment, regarding the sky image, the sky image actually taken, the sky image generated from the three-dimensional map information, and the sky image generated from the image taken from the in-vehicle camera Since the sky image generated from other information can be used, it is possible to provide more accurate positioning accuracy information at more points.

Therefore, according to the present embodiment, the processing load can be further reduced and the positioning accuracy information of the navigation satellite can be output.

1 ... Positioning accuracy information calculation system 10 ... Positioning accuracy information calculation device 11 ... Representative point determination unit 12 ... Satellite coordinate calculation unit 13 ... Approximate open space calculation unit 14 ... Visible satellite number calculation unit 15 ... Visible satellite number display unit 21 ... Satellite Information storage device 22 ... Sky image acquisition device 23 ... Three-dimensional map information storage device 24 ... In-vehicle camera image storage device 25 ... Sky photography image storage device

Claims (8)

A representative of a plurality of mesh points representing the positions of a plurality of regions, one mesh point being a representative point, including the representative point, and the plurality of mesh points in the vicinity of the representative point being defined as a plurality of neighborhood points. Point determination part and
A satellite coordinate calculation unit that acquires the position information of the representative point, acquires the orbit information of the satellite, and calculates the elevation angle of the satellite position at the target time at the representative point.
An approximate open space calculation unit that acquires a sky image for each of the plurality of neighboring points, identifies an open space from the sky image, and calculates a circular approximate open space centered on the zenith based on the open space. ,
It is characterized by including a visible satellite number calculation unit that calculates the number of visible satellites for each of the plurality of neighborhood points based on the elevation angle of the representative point and the approximate open space of each of the plurality of neighborhood points. Positioning accuracy information calculation device. The positioning accuracy information calculation device according to claim 1, wherein the representative point is the mesh point in the region including the center of gravity in the plurality of regions related to the plurality of neighboring points. The positioning accuracy information calculation device according to claim 1 or 2, wherein the representative point determining unit divides a target area into a mesh shape and determines different representative points when the groups of the neighboring points are different. The approximate open space calculation unit and acquires image generated from the three-dimensional map information, image generated from an image of the vehicle-mounted cameras, and what is available to any of the captured image the sky The positioning accuracy information calculation device according to any one of claims 1 to 3. The positioning accuracy information calculation device according to any one of claims 1 to 4, wherein the approximate open space calculation unit acquires the latest sky image when a plurality of sky images can be acquired. .. The positioning accuracy information calculation device according to any one of claims 1 to 5, further comprising a visible satellite number display unit that displays an image showing the number of visible satellites in each of the plurality of regions. The positioning accuracy information calculation device according to any one of claims 1 to 6, wherein the approximate open space includes a closed space as a part. Of the plurality of mesh points representing the positions of the plurality of regions, one mesh point is set as a representative point, the plurality of mesh points including the representative point and the vicinity of the representative point are defined as a plurality of neighborhood points.
The position information of the representative point is acquired, the orbit information of the satellite is acquired, and the elevation angle of the satellite position at the target time at the representative point is calculated.
A sky image is acquired for each of the plurality of neighboring points, an open space is identified from the sky image, and a circular approximate open space centered on the zenith is calculated based on the open space.
A positioning accuracy information calculation method, characterized in that the number of visible satellites for each of the plurality of neighborhood points is calculated based on the elevation angle of the representative point and the approximate open space of each of the plurality of neighborhood points.

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