Positioning system, mobile body, and positioning method

Abstract

This positioning system comprises an antenna that receives a satellite signal from a satellite, and a receiver that decodes the satellite signal received by the antenna to generate satellite information, the satellite information including at least a satellite position viewed from the antenna and a reception signal intensity. The positioning system further comprises: a visible range calculation unit that obtains a distribution of satellite positions at which the reception signal intensity is equal to or greater than a predetermined threshold and calculates a visible range from the distribution; and a positioning result output unit that outputs a positioning result on the basis of the satellite information of the satellite in the visible range. This makes it possible to achieve highly accurate positioning with a simple configuration.

Description

Positioning System, Mobile Body, and Positioning Method

[0001] The present invention relates to a positioning system, a mobile body, and a positioning method.

[0002] When moving outdoors, the Global Navigation Satellite System (GNSS: Global Navigation Satellite System) is a useful means for estimating position. However, when there are obstacles in the vicinity, the positioning result becomes unstable. As a countermeasure, there is the technology described in WO2020 / 013284 (Patent Document 1). This publication states, "Provided is a navigation satellite system receiver device capable of effectively eliminating multipath signals without direct waves of invisible satellites in a reception environment where the open space is severely restricted and realizing high-precision time synchronization or positioning. A satellite orbit information acquisition unit 42 that acquires orbit information of navigation satellites, an installation position information acquisition unit 43 that acquires position information of the installation position, an azimuth meter 3 that acquires azimuth information of the direction in which the wall surface of an obstacle in the vicinity extends, and an azimuth mask generation unit 44 that calculates a mask area for selecting navigation satellites to be processed based on the azimuth information. The positioning / time synchronization processing unit 45 calculates the azimuth and elevation angles of each navigation satellite based on the orbit information and the position information, selects the navigation satellites to be processed based on the calculated azimuth and elevation angles and the mask area, and performs at least one of the positioning processing or the time synchronization processing based on the navigation satellite signals received from the selected navigation satellites."

[0003] WO2020 / 013284

[0004] In the above prior art, detailed information about nearby obstacles is required, which complicates the configuration and the accuracy of the positioning result greatly depends on the accuracy of the obstacle information. Also, a decrease in the number of available satellites due to the mask is inevitable, and it is difficult to maintain the same accuracy as in an open sky environment.

[0005] Therefore, an object of the present invention is to achieve high-precision positioning with a simple configuration.

[0006] To achieve the above objective, one representative positioning system of the present invention is a positioning system comprising an antenna that receives satellite signals from satellites and a receiver that decodes the satellite signals received by the antenna and generates satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprises a visible range calculation unit that determines the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit that outputs a positioning result based on the satellite information of satellites within the visible range. Another representative mobile body of the present invention is a mobile body comprising an antenna that receives satellite signals from satellites and a receiver that decodes the satellite signals received by the antenna and generates satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprises a visible range calculation unit that determines the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit that outputs a positioning result based on the satellite information of satellites within the visible range. Furthermore, one representative positioning method of the present invention is a positioning method using a positioning system comprising an antenna that receives satellite signals from satellites and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and the positioning system is characterized by including the steps of: determining the distribution of satellite positions in which the received signal strength is above a predetermined threshold; calculating a visible range from the distribution; and outputting a positioning result based on the satellite information of satellites within the visible range.

[0007] According to the present invention, high-precision positioning can be achieved with a simple configuration. Other problems, configurations, and effects will be clarified by the following description of the embodiments.

[0008] Configuration diagram of the positioning system in Example 1 Flowchart showing the operation of the positioning system in Example 1 Diagram explaining the visible range Diagram explaining the generation and use of the visible range (1) Diagram explaining the generation and use of the visible range (2) Diagram explaining the generation and use of the visible range (3) Diagram explaining the generation and use of the visible range (4) Configuration diagram of the positioning system in Example 2 Diagram explaining movement and recalculation of the visible range (1) Diagram explaining movement and recalculation of the visible range (2) Diagram explaining vehicle type and obstacle height Flowchart showing the operation of the positioning system in Example 2 (1) Flowchart showing the operation of the positioning system in Example 2 (2) Configuration diagram of the positioning system in Example 3 Diagram explaining switching of representative visible ranges Diagram explaining integration of visible ranges Flowchart showing the processing procedure for determining the visible range in Example 3

[0009] The following describes an example using drawings.

[0010] Figure 1 is a diagram of the configuration of the positioning system of Embodiment 1. The positioning system 20 shown in Figure 1 is mounted on a vehicle and connected to an on-board GNSS antenna 10. The GNSS antenna 10 receives satellite signals from artificial satellites. The positioning system 20 includes a GNSS receiver 21, a visible range calculation unit 22, an evaluation unit 23, a positioning result output unit 24, and a storage device 25.

[0011] The GNSS receiver 21 decodes the satellite signal received by the GNSS antenna 10 to generate satellite information. The satellite information includes at least the satellite position as seen from the GNSS antenna 10 and the received signal strength. The GNSS receiver 21 calculates the position of the GNSS antenna 10 from the satellite information of multiple satellites. The position of the GNSS antenna 10 calculated by the GNSS receiver 21 is called the receiver positioning result. The receiver positioning result corresponds to the "first positioning result" in the claims.

[0012] The visible range calculation unit 22 determines the distribution of satellite positions where the received signal strength is above a predetermined threshold, and calculates the visible range from the distribution. As will be described in detail later, the visible range calculation unit 22 approximates the distribution of satellite positions where the received signal strength is above a predetermined threshold with an ellipse, and defines the resulting ellipse as the visible range. The visible range virtually represents the range of satellite positions that are not affected by obstacles.

[0013] The evaluation unit 23 determines the position of the GNSS receiver 21 from satellite information of multiple satellites within the visible range. The position of the GNSS antenna 10 calculated by the evaluation unit 23 is called the evaluation unit positioning result. The receiver positioning result corresponds to the "second positioning result" in the scope of the claim. Furthermore, the evaluation unit 23 determines whether the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to a threshold.

[0014] The positioning result output unit 24 outputs positioning results based on satellite information of satellites within the visible range. Specifically, the positioning result output unit 24 outputs the receiver positioning result and also outputs a warning flag as information indicating the difference between the receiver positioning result and the evaluation unit positioning result. If the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to a threshold, the value of the warning flag is "1". If the difference between the receiver positioning result and the evaluation unit positioning result is less than the threshold, the value of the warning flag is "0".

[0015] The storage device 25 stores data such as satellite information and receiver positioning results. The physical configuration of the GNSS receiver 21, the visible range calculation unit 22, the evaluation unit 23, the positioning result output unit 24, and the storage device 25 can be designed arbitrarily. For example, the visible range calculation unit 22, the evaluation unit 23, and the positioning result output unit 24 may implement their corresponding functions by having a CPU (Central Processing Unit) execute a predetermined program. In this case, the GNSS receiver 21 can be treated as a single unit and connected to the CPU and any storage device as the storage device 25 to realize the positioning system 20.

[0016] Figure 2 is a flowchart showing the operation of the positioning system 20 of Embodiment 1. The positioning system 20 sequentially executes steps S101 to S113. Step S101 The GNSS antenna 10 receives satellite radio waves, i.e., satellite signals. Then proceed to step S102. Step S102 The GNSS receiver 21 decodes the satellite signals and performs carrier wave analysis to obtain satellite information and receiver positioning results. Then proceed to step S103. Step S103 The GNSS receiver 21 transmits the satellite information (position of each observed satellite, received signal strength, distance between satellite antennas) and receiver positioning results, along with the calculated time, to the visible range calculation unit 22, the storage device 25, and the positioning result output unit 24, respectively. Then proceed to step S104.

[0017] Step S104 The visible range calculation unit 22 lists the satellites with high received signal strength (satellites with a signal strength above a predetermined threshold) from among the satellites obtained from the GNSS receiver 21. Then, the process proceeds to step S105. Step S105 The line of sight center is calculated from the satellite positions of all the listed satellites. The line of sight center may be, for example, the average of the satellite positions, or it may be statistically determined from density, etc. Then, the process proceeds to step S106.

[0018] Step S106 The visible range calculation unit 22 sets a certain range from the center of the line of sight as the visible range and selects satellites within the visible range from a list. Then proceed to step S107. Step S107 The visible range calculation unit 22 sends the selected satellites to the evaluation unit 23. Then proceed to step S108.

[0019] Step S108 The evaluation unit 23 performs positioning using satellites within the visible range. Then proceed to step S109. Step S109 The evaluation unit 23 compares the evaluation unit positioning result, which is the positioning result it calculated itself, with the receiver positioning result. Then proceed to step S110.

[0020] Step S110 If the difference between the receiver positioning result and the evaluation unit positioning result is less than the threshold, the evaluation unit 23 proceeds to step S111. If the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to the threshold, the evaluation unit 23 proceeds to step S112. Step S111 The evaluation unit 23 sets the warning flag to "0" and proceeds to step S113. Step S112 The evaluation unit 23 sets the warning flag to "1" and proceeds to step S113. Step S113 The positioning result output unit 24 outputs the receiver positioning result and the warning flag and terminates the process.

[0021] Figure 3 is an explanatory diagram of the visible range. The visible range 12 is set relative to the GNSS antenna 10 mounted on the vehicle. The center of the visible range 12 is determined by the line-of-sight vector from the GNSS antenna 10 to the center of the line of sight. The visible range 12 is elliptical. The positioning system 20 uses satellites 11 located inside the visible range 12 to perform positioning, thereby suppressing the effects of obstacles and achieving highly accurate positioning.

[0022] Referring to Figures 4 to 7, the generation and use of the visible range will be explained. First, as shown in Figure 4, the positioning system 20 excludes satellites 11 whose signal-to-noise ratio (SNR) is below a certain value. Next, as shown in Figure 5, the positioning system 20 approximates the distribution range of satellites 11 whose SNR is above a certain value as an ellipse and calculates the center, major axis, minor axis, and major axis direction. The positioning system 20 defines the area within the ellipse as the visible range 12.

[0023] Next, as shown in Figure 6, the positioning system 20 excludes satellites 11 that are outside the visible range. This is equivalent to setting a mask by referring to a map that shows the locations of obstacles, etc. In other words, the influence of obstacles is reduced by the visible range 12 without using map data.

[0024] Next, as shown in Figure 7, the positioning system 20 performs relative positioning using the remaining satellites and the receiver positioning results. The most reliable receiver positioning result from a certain period in the past may be used as the receiver positioning result.

[0025] As described above, the positioning system 20 shown in Example 1 can achieve high-precision positioning with a simple configuration without using external map data or the like. In Example 1, a configuration was described in which positioning results based on the visible range are used to evaluate the receiver positioning results, but a configuration that outputs positioning results based on the visible range may also be used. When outputting positioning results based on the visible range, a position calculation unit is provided instead of the evaluation unit 23, and position information calculated from satellite information of multiple satellites within the visible range is output as the positioning result. In this case, the GNSS receiver 21 does not need to calculate the receiver positioning result. Alternatively, the GNSS receiver 21 may calculate the receiver positioning result and output both the positioning result from the position calculation unit and the receiver positioning result. Furthermore, the receiver positioning result may be used to evaluate the positioning result from the position calculation unit.

[0026] Figure 8 is a diagram showing the configuration of the positioning system of Embodiment 2. The positioning system 20a shown in Figure 8 differs from Embodiment 1 in that it further includes a relative positioning unit 26. Also, the operation of the visible range calculation unit 22 differs in part from that of Embodiment 1. The other configurations and operations are the same as in Embodiment 1, so the same reference numerals are used for the same components and their descriptions are omitted.

[0027] The relative positioning unit 26 is a movement information calculation unit that calculates movement information including the direction and distance of movement of the GNSS antenna 10. The relative positioning unit 26 acquires and stores receiver positioning results from the GNSS receiver 21. When a new receiver positioning result is acquired, it calculates the movement information of the GNSS antenna 10 by comparing it with past receiver positioning results.

[0028] In Embodiment 2, when the GNSS antenna 10 moves by more than a threshold, the visible range calculation unit 22 acquires obstacle information indicating the height of obstacles located around the visible range, and recalculates the visible range using the movement information and obstacle information.

[0029] Figures 9 and 10 are explanatory diagrams regarding movement and recalculation of the visible range. First, as shown in Figure 9, if an obstacle exists near the GNSS antenna 10, the visible center (center of the visible range) shifts to the opposite side of the obstacle, centered on the antenna position. When the GNSS antenna 10 moves in the presence of such an obstacle, the visible satellites change. Considering that the main cause of the change in visible satellites is shielding by obstacles, it is preferable to change the range that masks the satellites, i.e., the visible range, depending on the direction of movement of the antenna position. When the antenna position moves in the direction of the visible center, the vehicle is moving away from the obstacle. When the antenna position moves in the opposite direction to the visible center, the vehicle is moving towards the obstacle. The ellipse becomes smaller as it approaches the obstacle and larger as it moves away. From these points, the ellipse is enlarged by virtually moving the visible center, with θ being the angle between the azimuth from the antenna position to the visible center and the direction of travel.

[0030] As shown in Figure 10, when the amount of antenna movement is ν, the amount of movement in the direction of the visible center is ν × cosθ. Let η be the angle between the nearest point to the antenna on the outer edge of the visible range and the antenna position, and let h be the height of the obstacle. Due to the movement of the antenna, η ０ from η １ If it changes to η １ = h × tan(η) ０ ) / (h+ν×cosθtan(η ０ )) The visible range calculation unit 22 moves the visible center toward the antenna position η ０ -η １ By moving only that much and recalculating the major and minor axes, the visible range after the move is recalculated.

[0031] The obstacle height h is determined not by the height of the actual obstacles in the surrounding area, but by the area in which the vehicle is traveling. If the vehicle's use is specified by its type, it is also possible to determine the obstacle height by identifying the area in which the vehicle will be used based on its type.

[0032] Figure 11 is an explanatory diagram of vehicle types and obstacle heights. If the positioning system 20a is installed on construction machinery used in urban areas, the estimated obstacle height is 50m. If the positioning system 20a is installed on construction machinery used in rural areas, the estimated obstacle height is 20m. If the positioning system 20a is installed on agricultural machinery used in mountainous areas, the estimated obstacle height is 20m. If the positioning system 20a is installed in agriculture used in plains, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used within a company premises, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used on public roads, the estimated obstacle height is 10m. If the positioning system 20a is installed on work machinery used on expressways, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used on the Metropolitan Expressway, the estimated obstacle height is 20m. The positioning system 20a maintains a table showing these correspondences and reads out and uses the estimated obstacle altitude corresponding to the vehicle on which it is mounted.

[0033] Figures 12 and 13 are flowcharts showing the operation of the positioning system 20a in Example 2. The operation of the positioning system 20a differs from that of Example 1 in that steps S201 to S203 are inserted between steps S107 and S108. The other steps are the same as in Example 1, so their explanation is omitted.

[0034] Step S201 After step S107, the relative positioning unit 26 calculates the relative position from the past position. Then proceed to step S202. Step S202 The relative positioning unit 26 determines whether the amount of antenna movement is greater than or equal to a threshold. If it is less than the threshold, proceed to step S108. If it is greater than or equal to the threshold, proceed to step S203. Step S203 The visible range calculation unit 22 acquires obstacle information and recalculates the visible range using the movement information and obstacle information. Then proceed to step S108.

[0035] As described above, the positioning system 20a shown in Example 2 can respond to antenna movement with a simple configuration and achieve high-precision positioning without using detailed map data or the like. In Example 2, antenna movement was evaluated by changes in the receiver positioning results, but antenna movement may also be determined by acquiring information about movement from the vehicle.

[0036] Figure 14 is a configuration diagram of the positioning system of Embodiment 3. The positioning system 20b shown in Figure 13 differs from Embodiment 2 in that it further includes a visible range storage unit 27. Also, the operation of the visible range calculation unit 22 differs in part from that of Embodiment 2. The other configurations and operations are the same as in Embodiment 2, so the same reference numerals are used for the same components and their descriptions are omitted.

[0037] The visible range calculation unit 22 of Embodiment 3 can generate multiple visible ranges for a given time. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 uses one of them as a representative visible range for positioning. To simplify the explanation, we will describe the case where up to two visible ranges are generated as an example. The two visible ranges are distinguished as the first visible range and the second visible range, and the first visible range is designated as the representative visible range.

[0038] In Embodiment 3, the visible range calculation unit 22 registers and stores one or more generated visible ranges in the visible range storage unit 27. Furthermore, when calculating visible ranges, the visible range calculation unit 22 refers to past visible ranges stored in the visible range storage unit 27 to switch representative visible ranges, merge visible ranges, and delete visible ranges.

[0039] Figure 15 is an explanatory diagram for switching representative visible ranges. The visible range calculation unit 22 evaluates the change in area of ​​multiple visible ranges using the newly calculated visible range and the visible range stored in the visible range storage unit 27, and if the area of ​​a representative visible range becomes smaller than that of other visible ranges, it sets the other visible range as the new representative visible range.

[0040] In FIG. 15, the visible range calculation unit 22 monitors the magnification ratios of the first visible range, which is the representative visible range, and the second visible range. When the first visible range has a shrinking tendency, the second visible range has an expanding tendency, and the area of the second visible range exceeds the area of the first visible range, the visible range calculation unit 22 switches between the first visible range and the second visible range.

[0041] FIG. 16 is an explanatory diagram of the integration of visible ranges. The visible range calculation unit 22 evaluates the change in the overlapping range between the newly calculated visible range and the visible range stored in the visible range storage unit 27, and when the overlapping range exceeds half of the area of the representative visible range, integrates the representative visible range and the other visible range and recalculates the visible range.

[0042] Here, the elimination of the visible range will be described. When there are no satellites within the visible range or when either the major axis or the minor axis becomes smaller than a certain threshold value, the visible range calculation unit 22 eliminates the corresponding visible range.

[0043] FIG. 17 is a flowchart showing the processing procedure for determining the visible range in the third embodiment. The series of processes in FIG. 17 is included in step S106 shown in the first embodiment. After calculating the new visible range, the visible range calculation unit 22 sequentially executes steps S301 to S317.

[0044] Step S301: The visible range calculation unit 22 determines whether the second visible range exists in the visible range storage unit 27. If the second visible range exists, the process proceeds to step S302. If the second visible range does not exist, the process proceeds to step S309.

[0045] Step S302: The visible range calculation unit 22 acquires the line-of-sight center of the second visible range. Then, the process proceeds to step S303. Step S303: The visible range calculation unit 22 calculates the second visible range. Then, the process proceeds to step S304. Step S304: The visible range calculation unit 22 calculates the magnification ratios from the previous visible range for the first and second visible ranges. Then, the process proceeds to step S305.

[0046] Step S305 The visible range calculation unit 22 determines whether the magnification ratio of the first visible range is less than 1. If the magnification ratio of the first visible range is 1 or greater, proceed to step S306. If the magnification ratio of the first visible range is less than 1, proceed to step S313. Step S306 The visible range calculation unit 22 calculates the overlapping range of the first visible range and the second visible range. Then proceed to step S307. Step S307 The visible range calculation unit 22 determines whether the overlapping range is half or more of the first visible range. If the overlapping range is half or more of the first visible range, proceed to step S308. If the overlapping range is less than half of the first visible range, proceed to step S316. Step S308 The visible range calculation unit 22 integrates the visible ranges by recalculating the visible ranges. Then proceed to step S316.

[0047] Step S309 The visible range calculation unit 22 determines whether or not there are visible satellites outside the visible range. If there are no visible satellites, proceed to step S316. If there are visible satellites outside the visible range, proceed to step S310. Step S310 The visible range calculation unit 22 lists the visible satellites that are outside the visible range. Then proceed to step S311. Step S311 The visible range calculation unit 22 calculates the visible range from the listed satellite positions. Then proceed to step S312. Step S312 The visible range calculation unit 22 sets the calculated visible range as the second visible range. Then proceed to step S316.

[0048] Step S313 The visible range calculation unit 22 determines whether the magnification ratio of the second visible range is less than 1. If the magnification ratio of the second visible range is 1 or greater, proceed to step S314. If the magnification ratio of the second visible range is less than 1, proceed to step S306. Step S314 The visible range calculation unit 22 determines whether the area of ​​the first visible range is smaller than the area of ​​the second visible range. If the area of ​​the first visible range is smaller than the area of ​​the second visible range, proceed to step S315. If the area of ​​the first visible range is greater than or equal to the area of ​​the second visible range, proceed to step S316. Step S315 The visible range calculation unit 22 switches the visible range by setting the second visible range to the first visible range. Then proceed to step S316.

[0049] Step S316 The visible range calculation unit 22 stores the first visible range and the second visible range in the visible range storage unit 27. Then, the process proceeds to step S317. Step S317 The visible range calculation unit 22 selects the satellites in the first visible range as targets to output to the evaluation unit. Then, the process shown in Figure 17 is completed, and the process proceeds to step S107.

[0050] Thus, the positioning system 20b shown in Example 3 can achieve highly accurate positioning by setting multiple visible ranges.

[0051] As described above, the positioning system 20 disclosed in the embodiment comprises a GNSS antenna 10, which is an antenna that receives satellite signals from satellites, and a GNSS receiver 21, which is a receiver that decodes the satellite signals received by the antenna and generates satellite information. The positioning system includes at least the satellite position as seen from the antenna and the received signal strength in the satellite information, and further comprises a visible range calculation unit 22 that determines the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit 24 that outputs a positioning result based on the satellite information of satellites within the visible range. With this configuration, the positioning system 20 can achieve highly accurate positioning with a simple configuration.

[0052] Furthermore, the positioning system 20 further includes a relative positioning unit 26 as a movement information calculation unit that calculates movement information including the direction and distance of movement of the antenna, and the visible range calculation unit 22 acquires obstacle information indicating the height of obstacles located around the visible range when the antenna moves, and recalculates the visible range using the movement information and the obstacle information. With this configuration, highly accurate positioning can be achieved by reflecting the movement state.

[0053] Furthermore, the obstacle information includes the height of the nearest obstacle to the antenna on the outer edge of the visible range. With this configuration, high-precision positioning can be achieved by referring to information indicating the height of surrounding obstacles and reflecting the movement state.

[0054] In one configuration example, the receiver further includes an evaluation unit 23 that calculates the position of the antenna as a first positioning result from satellite information of multiple satellites, and calculates the position of the antenna as a second positioning result from satellite information of multiple satellites within the visible range. The positioning result output unit 24 outputs the first positioning result and also outputs information indicating the difference between the first positioning result and the second positioning result. With this configuration, by adding information to the positioning result from the receiver, it is possible to notify the result of highly accurate positioning.

[0055] In one configuration example, the system further includes a position calculation unit that calculates the position of the antenna from satellite information of multiple satellites within the visible range, and the positioning result output unit outputs the position of the antenna calculated by the position calculation unit as the positioning result. With this configuration, highly accurate positioning results obtained from satellites within the visible range can be output.

[0056] In one configuration example, the system further includes a visible range storage unit 27 that stores the visible range calculated by the visible range calculation unit 22. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 selects one of the multiple visible ranges as a representative visible range. The positioning result output unit 24 outputs a positioning result based on the satellite information of the satellite in the representative visible range. The visible range calculation unit 22 evaluates the change in the area of ​​the multiple visible ranges using the newly calculated visible range and the visible ranges stored in the visible range storage unit. If the area of ​​the representative visible range becomes smaller than that of the other visible ranges, the other visible range becomes the new representative visible range. With this configuration, multiple visible ranges can be set and the representative visible range can be switched.

[0057] In one configuration example, the system further includes a visible range storage unit 27 that stores the visible range calculated by the visible range calculation unit 22. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 selects one of the multiple visible ranges as a representative visible range. The positioning result output unit 24 outputs a positioning result based on the satellite information of the satellite in the representative visible range. The visible range calculation unit 22 uses the newly calculated visible range and the visible range stored in the visible range storage unit 27 to evaluate the change in the overlapping area between the representative visible range and other visible ranges. If the overlapping area exceeds half the area of ​​the representative visible range, the system integrates the representative visible range and other visible ranges and recalculates the visible range. This configuration allows for the setting and integration of multiple visible ranges.

[0058] Furthermore, the visible range calculation unit 22 approximates the distribution of satellite positions where the received signal strength is above a predetermined threshold as an ellipse, and defines the resulting ellipse as the visible range. With this configuration, the visible range can be determined with a simple process.

[0059] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace or add configurations, not just delete them. For example, although the above embodiments were explained using a vehicle as an example, they can also be applied to ships, etc.

[0060] 10: GNSS antenna, 11: satellite, 12: visible range, 20: positioning system, 21: GNSS receiver, 22: visible range calculation unit, 23: evaluation unit, 24: positioning result output unit, 25: memory device, 26: relative positioning unit, 27: visible range storage unit

Claims

1. A positioning system comprising: an antenna for receiving satellite signals from satellites; a receiver for decoding the satellite signals received by the antenna and generating satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprising: a visible range calculation unit for determining the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculating a visible range from the distribution; and a positioning result output unit for outputting a positioning result based on the satellite information of satellites within the visible range.

2. A positioning system according to claim 1, further comprising a movement information calculation unit that calculates movement information including the direction and distance of movement of the antenna, wherein the visible range calculation unit acquires obstacle information indicating the height of obstacles located around the visible range when the antenna moves, and recalculates the visible range using the movement information and the obstacle information.

3. A positioning system according to claim 2, wherein the obstacle information includes the height of the nearest obstacle to the antenna on the outer periphery of the visible range.

4. A positioning system according to claim 1, wherein the receiver further comprises an evaluation unit that calculates the position of the antenna as a first positioning result from satellite information of a plurality of satellites, and calculates the position of the antenna as a second positioning result from satellite information of a plurality of satellites within the visible range, and the positioning result output unit outputs the first positioning result and also outputs information indicating the difference between the first positioning result and the second positioning result.

5. A positioning system according to claim 1, further comprising a position calculation unit that calculates the position of the antenna from satellite information of a plurality of satellites within the visible range, wherein the positioning result output unit outputs the position of the antenna calculated by the position calculation unit as the positioning result.

6. A positioning system according to claim 1, further comprising a visible range storage unit that stores a visible range calculated by the visible range calculation unit, wherein the visible range calculation unit selects one of the multiple visible ranges as a representative visible range when multiple visible ranges exist simultaneously, the positioning result output unit outputs a positioning result based on satellite information of the satellite in the representative visible range, and the visible range calculation unit evaluates the change in the area of ​​the multiple visible ranges using the newly calculated visible range and the visible range stored in the visible range storage unit, and if the area of ​​the representative visible range becomes smaller than that of the other visible ranges, the other visible range is designated as the new representative visible range.

7. A positioning system according to claim 1, further comprising a visible range storage unit that stores a visible range calculated by the visible range calculation unit, wherein the visible range calculation unit selects one of the multiple visible ranges as a representative visible range when multiple visible ranges exist simultaneously, the positioning result output unit outputs a positioning result based on satellite information of the satellite in the representative visible range, and the visible range calculation unit evaluates the change in the overlapping range between the representative visible range and other visible ranges using the newly calculated visible range and the visible range stored in the visible range storage unit, and if the overlapping range exceeds half the area of ​​the representative visible range, it integrates the representative visible range and other visible ranges to recalculate the visible range.

8. A positioning system according to claim 1, wherein the visible range calculation unit approximates the distribution of satellite positions where the received signal strength is above a predetermined threshold with an ellipse, and the obtained ellipse is defined as the visible range.

9. A mobile body comprising: an antenna for receiving satellite signals from a satellite; a receiver for decoding the satellite signals received by the antenna and generating satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength; a visible range calculation unit for determining the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculating a visible range from the distribution; and a positioning result output unit for outputting a positioning result based on the satellite information of satellites within the visible range.

10. A positioning method using a positioning system comprising an antenna that receives satellite signals from a satellite and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, the positioning method being characterized by the positioning system comprising the steps of: determining the distribution of satellite positions in which the received signal strength is above a predetermined threshold; calculating a visible range from the distribution; and outputting a positioning result based on the satellite information of satellites within the visible range.

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