Mobile positioning system and mobile positioning switching method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KK TOSHIBA
- Filing Date
- 2022-11-29
- Publication Date
- 2026-08-03
Smart Images
Figure 0007899069000003 
Figure 0007899069000004 
Figure 0007899069000005
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a mobile body positioning system and a mobile body positioning switching method.
Background Art
[0002] Conventionally, in a mobile body such as a railway vehicle, as a positioning system for positioning the position of the mobile body, there is known a positioning system including both a satellite positioning device using GNSS (Global Navigation Satellite System) or the like and an autonomous positioning device using an acceleration sensor, a gyro sensor, or the like. In a satellite positioning system including a satellite positioning device and an autonomous positioning device, when the reception state in the satellite positioning device deteriorates, it is switched to the autonomous positioning device, and when the reception state improves again, it is switched back to the satellite positioning device to keep the position measurement accuracy constant.
Prior Art Documents
Patent Documents
[0006] The mobile positioning system of the embodiment is a mobile positioning system mounted on a mobile body that determines the position of the mobile body, and comprises: a first satellite positioning unit that receives positioning radio waves from an artificial satellite and determines the first position of the mobile body; a second satellite positioning unit that receives positioning radio waves from an artificial satellite and determines the second position of the mobile body; an autonomous positioning unit that autonomously determines the third position of the mobile body; a standalone positioning mode in which the position of the mobile body is determined by either the first or second satellite positioning unit; a relative positioning mode in which the position of the mobile body is determined by the first and second satellite positioning units; and an autonomous positioning mode in which the position of the mobile body is determined by the autonomous positioning unit, and comprises a control unit that exclusively selects one of the positioning modes, and the control unit prohibits direct transitions between the autonomous positioning mode and the relative positioning mode. Furthermore, when switching positioning modes between the standalone positioning mode and the relative positioning mode, the elevation angle is set to a predetermined minimum value so that the number of satellites to be acquired can be increased, and the reception strength of the satellite radio waves of the satellites to be acquired is set to a predetermined minimum value so that the first satellite positioning unit and the second satellite positioning unit are instructed to acquire satellites. . [Brief explanation of the drawing]
[0007] [Figure 1] Figure 1 is a block diagram illustrating the schematic configuration of the positioning system according to the embodiment. [Figure 2] Figure 2 is a processing flowchart (part 1) of the embodiment. [Figure 3] Figure 3 is a flowchart showing the process for determining whether or not the relative positioning transition conditions are met. [Figure 4] Figure 4 is an explanatory diagram illustrating an example of the number of satellites to be captured when the elevation angle is ≥ 30°. [Figure 5] Figure 5 is an explanatory diagram illustrating an example of the number of satellites captured when the elevation angle is ≥ 20° at the same time as in Figure 4. [Figure 6] Figure 6 is an explanatory diagram illustrating an example of the number of satellites captured when the elevation angle is ≥ 5° at the same time as in Figure 4. [Figure 7] Figure 7 is a processing flowchart (part 2) of the embodiment. [Figure 8] Figure 8 is a processing flowchart (part 3) of the embodiment. [Figure 9] Figure 9 is a conceptual diagram illustrating the positioning status. [Figure 10]Figure 10 is a flowchart (part 1) for determining the state of excessive error. [Figure 11] Figure 11 is a flowchart (part 2) for determining the state of excessive error. [Modes for carrying out the invention]
[0008] Embodiments will be described with reference to the drawings. Figure 1 is a block diagram illustrating the schematic configuration of the positioning system according to the embodiment. The positioning system 10 is mounted on a railway vehicle TR and includes a first satellite positioning unit 21, a second satellite positioning unit 22, an autonomous positioning unit 23, and a position measurement calculation processing unit 24.
[0009] The first satellite positioning unit 21, for example, configures a GNSS (Global Navigation Satellite System), receives positioning radio waves from positioning satellites to perform positioning (satellite positioning) of the railway vehicle TR, and outputs the first satellite positioning result data DP1 to the position measurement calculation processing unit 24.
[0010] The second satellite positioning unit 22, for example, constitutes a GNSS and is positioned at a predetermined distance from the first satellite positioning unit 21. It receives positioning radio waves from positioning satellites to perform positioning (satellite positioning) of the railway vehicle TR and outputs the second satellite positioning result data DP2 to the position measurement calculation processing unit 24.
[0011] Here, GNSS is a general term for satellite positioning systems such as the US GPS, Japan's Quasi-Zenith Satellite System (QZSS), Russia's GLONASS (GLO), the European Union's Galileo (GAL), and China's Beidou (BDS). Therefore, the receivers comprising the first satellite positioning unit 21 and the second satellite positioning unit 22 are configured to be able to perform positioning using either of those satellite positioning systems.
[0012] The self-positioning unit 23 includes, for example, self-positioning sensors such as an acceleration sensor and a gyro sensor, performs self-positioning of the railway vehicle TR independently, and outputs self-positioning result data DS to the position measurement calculation processing unit 24.
[0013] The position measurement calculation processing unit 24 functions as a control unit, calculates the position of the railway vehicle TR based on the first satellite positioning result data, the second satellite positioning result data, and the self-positioning result data, and outputs it as position information data.
[0014] In the above configuration, the positioning system 10 has three positioning modes: a single positioning (mode) that performs positioning based on either the positioning result of the first satellite positioning unit 21 or the positioning result of the second satellite positioning unit 22 based on the positioning states of the first satellite positioning unit 21 and the second satellite positioning unit 22; a relative positioning (mode) that performs positioning based on the positioning results of the first satellite positioning unit 21 and the second satellite positioning unit 22; and a self-positioning (mode) that performs positioning based on the positioning result of the self-positioning unit 23.
[0015] The single positioning (mode) receives information such as the position and time of satellites transmitted from GNSS satellites with a single receiver, and performs positioning based on the information obtained by the receiver. In single positioning, using GNSS satellites with known positions as moving reference points, the position of the observation point is determined from four or more satellites. It is mainly used for positioning moving objects.
[0016] The relative positioning (mode) uses two or more receivers and receives signals from four or more of the same GNSS satellites simultaneously. Based on the positions of GNSS satellites, the time difference for radio signals from GNSS satellites to reach each receiver is measured to obtain the relative positional relationship between two points and determine the position of one point. It is mainly used for surveying.
[0017] The autonomous positioning (mode) uses information from various sensors, such as gyro sensors, accelerometers, and speed generators (TGs), to perform calculations and determine the position of observation points with high accuracy, even in environments where GNSS alone cannot maintain positioning.
[0018] In this case, the positioning accuracy is generally highest in relative positioning mode, followed by standalone positioning mode, and lowest in autonomous positioning mode. On the other hand, the conditions for positioning are most stringent for relative positioning, followed by standalone positioning, and autonomous positioning is the easiest.
[0019] By the way, when switching positioning modes, in order to stably maintain the new positioning mode, it is desirable not only to satisfy the positioning conditions but also to easily satisfy the switching conditions of the new mode, and to perform the switch while there is sufficient margin in the switching conditions of the original mode, in order to suppress the frequency of switching and continue stable positioning.
[0020] Therefore, in this embodiment, direct transitions between autonomous positioning (mode) and relative positioning (mode) are prohibited, and the system is configured to first transition to standalone positioning (mode). Furthermore, when switching to standalone positioning (mode) or relative positioning (mode), the elevation angle and the satellite signal strength used to determine the target satellite are set to their minimum values beforehand, and the number of target satellites is increased to increase the acquisition rate.
[0021] Furthermore, in order to reduce the frequency of switching, the source positioning mode can be switched if some of the switching conditions are met, while the destination positioning mode can only be switched if all (or more) of the switching conditions are met, in order to ensure stable positioning after the switch.
[0022] As a result, while positioning is stable in the original positioning mode, the system can transition to a more stable target positioning mode. This reduces the time it takes to reach a point where another switch is necessary, thus suppressing the frequency of positioning changes.
[0023] Next, the operation of the embodiment will be described. Figure 2 is a processing flowchart (part 1) of the embodiment. First, let's explain the case where the previous positioning was a standalone positioning at startup (when the power is turned on). In this case, even if the previous positioning was relative positioning, it will be treated as if the previous positioning was single-point positioning. This is because satellite configurations and other factors are likely to have changed at startup, so this ensures that positioning can be started reliably. If the previous positioning was single-positioning at startup (when power is turned on), single-positioning is maintained (step S11). During standalone positioning, it is determined whether or not a state of excessive error in standalone positioning has occurred (step S12). More specifically, for example, in a standalone positioning state, if two or more of the following conditions for transitioning to autonomous positioning (1) to (4) are met, it indicates an excessive error state. Therefore, it is determined whether or not two or more of the conditions for transitioning to autonomous positioning have been met. Note that the specific numerical values used as criteria in the following explanation are provided for ease of understanding and can be set as appropriate. (1) Estimated distance error ΔL>0.05m) (2) PACC 3D > 0.5m (3) PACC 3D%>2% (4) Number of satellites used for positioning: <15 The number of conditions and settings for the transitions can be changed as needed.
[0024] In the determination in step S12, if one or fewer of the conditions for transitioning to autonomous positioning are met (step S12; No), then the state of excessive error has not been reached, and independent positioning is continued (step S13).
[0025] Next, during standalone positioning, it is determined whether the following relative positioning transition conditions (1) to (3) are met, that is, whether all relative positioning transition conditions are satisfied (step S14). (1) The receiver is operating in moving base mode. Here, mobile base station mode refers to the relative position of two moving receivers. This is the operating mode of receivers that perform positioning at the same time, and is a prerequisite for relative positioning. This is the operating mode of the signaling device. (2) Average received signal strength of satellites used for positioning ≥ 40 dBHz (3) Total number of captured satellites ≧30 The number of conditions and settings for the transitions can be changed as needed.
[0026] Here, we will explain in detail the process for determining whether or not the relative positioning transition conditions in step S14 are met. Figure 3 is a flowchart showing the process for determining whether or not the relative positioning transition conditions are met. First, the receiver is given operational status information to determine whether or not it is operating in moving base mode (step S21).
[0027] Next, based on the operating status information acquired in step S21, it is determined whether or not the receiver is operating in moving base mode (step S22). In the determination in step S22, if the receiver is not operating in mobile base station mode (step S22; No), it is determined that not all relative positioning transition conditions are met (step S23), and the determination process in step S14 is terminated.
[0028] In the determination in step S22, if the receiver is operating in mobile base station mode (step S22; Yes), it is determined whether the average received signal strength of the satellites used for positioning is 40 dB Hz or higher (step S24).
[0029] In the determination in step S24, if the average received signal strength of the satellites used for positioning is less than 40 dBHz (step S24; No), it is determined that the relative positioning transition conditions are not all met, i.e., the relative positioning transition conditions are insufficient (step S23), and the determination process in step S14 is terminated.
[0030] In the determination in step S24, if the average received signal strength of the satellites used for positioning is 40 dBHz or higher (step S24; Yes), then it is determined whether the total number of acquired satellites is 30 or higher (step S25).
[0031] In the determination in step S25, if the total number of acquired satellites is less than 30 (step S25; No), it is determined that the relative positioning transition conditions are not all met, i.e., the relative positioning transition conditions are insufficient (step S23), and the determination process in step S14 is terminated.
[0032] In the determination in step S25, if the total number of acquired satellites is 30 or more (step S25; Yes), it is determined that all relative positioning transition conditions are met, i.e., the relative positioning transition conditions are complete (step S26), and the determination process in step S14 is terminated.
[0033] As a result of these considerations, if, in the judgment of step S24, all relative positioning transition conditions are not met, i.e., if the relative positioning transition conditions are insufficient (step S24; No), the process returns to step S13 and standalone positioning is maintained.
[0034] If, in the determination in step S24, it is determined that the conditions for transitioning to relative positioning are met (step S24; Yes), the switching from standalone positioning to relative positioning is initiated (step S15), and the process proceeds to step S31 (see Figure 7).
[0035] In this case, after switching from standalone positioning to relative positioning, the elevation angle and other parameters are narrowed, which may cause the system to lose track of satellites. Therefore, immediately after the switch, the elevation angle and the satellite signal strength used to determine the target satellites are set to the lowest value, and the number of target satellites is increased to improve the acquisition rate.
[0036] Here, we will explain an example of the relationship between elevation angle and the number of captured satellites. Figure 4 is an explanatory diagram illustrating an example of the number of satellites to be captured when the elevation angle is ≥ 30°. In a GNSS positioning system, the receiver is equipped with receivers for GPS and QZSS, GLO, GAL, and BDS. Therefore, Figure 4 shows the cases for GPS and QZSS, GLO, GAL, and BDS, respectively.
[0037] As shown in Figure 4, the GPS and QZSS receivers have a total of 7 satellites: 5 for the GPS positioning system and 2 for the QZSS positioning system.
[0038] In this case, HDOP (horizontal dilution of precision) = 1.51 and VDOP (vertical dilution of precision) = 2.60. Furthermore, although the satellites are evenly distributed, the number of satellites that can be acquired is low, making it somewhat unsuitable for positioning (△).
[0039] Furthermore, as shown in Figure 4, the GLO receiver has a targeting count of 4 satellites in the GLO positioning system. In this case, HDOP=18.44 and VDOP=45.7. Therefore, the accuracy degradation rate is large, the number of acquired satellites is small, and the system is unsuitable for positioning (×).
[0040] Furthermore, as shown in Figure 4, the GAL receiver has a targeting count of 4 satellites in the GAL positioning system. In this case, HDOP=2.53 and VDOP=13.4. Therefore, the rate of accuracy degradation is also large, the number of acquired satellites is small, and the system is unsuitable for positioning (×).
[0041] Furthermore, as shown in Figure 4, the BDS receiver has a targeting count of 13 satellites in the BDS positioning system.
[0042] In this case, HDOP=1.12 and VDOP=2.21, the accuracy degradation rate is small, and although the satellite configuration is aligned from the southwest, the number of acquired satellites is large, making it suitable for positioning (○).
[0043] Figure 5 is an explanatory diagram illustrating an example of the number of satellites captured when the elevation angle is ≥ 20° at the same time as in Figure 4. As shown in Figure 5, the GPS and QZSS receivers have a total of 11 satellites: 8 for the GPS positioning system and 3 for the QZSS positioning system.
[0044] In this case, HDOP=0.95 and VDOP=1.44. Furthermore, although the satellites are evenly distributed, the number of satellites that can be acquired is small, making it suitable for positioning (○).
[0045] Furthermore, as shown in Figure 5, the GLO receiver has a targeting count of 5 satellites in the GLO positioning system. In this case, HDOP=1.83 and VDOP=3.55, indicating a small rate of accuracy degradation, but the number of acquired satellites is insufficient, making it unsuitable for positioning (×).
[0046] Furthermore, as shown in Figure 5, the GAL receiver has a targeting count of 4 satellites in the GAL positioning system. In this case, HDOP=2.53 and VDOP=13.4, indicating a somewhat large rate of accuracy degradation, a low number of acquired satellites, and a state unsuitable for positioning (×).
[0047] Furthermore, as shown in Figure 5, the BDS receiver has a targeting count of 17 satellites in the BDS positioning system. In this case, HDOP=0.82 and VDOP=1.29, the accuracy degradation rate is small, and although the satellite configuration is aligned from the southwest, the number of acquired satellites is large, making it a more suitable condition for positioning (◎).
[0048] Figure 6 is an explanatory diagram illustrating an example of the number of satellites captured when the elevation angle is ≥ 5° at the same time as in Figure 4. As shown in Figure 6, the GPS and QZSS receivers have a total of 16 satellites: 12 for the GPS positioning system and 4 for the QZSS positioning system. In this case, HDOP=0.66 and VDOP=0.91, the accuracy degradation rate is small, and the satellites are evenly distributed, making it a more suitable condition for positioning (◎).
[0049] Furthermore, as shown in Figure 6, the GLO receiver has a targeting count of 8 satellites in the GLO positioning system. In this case, HDOP=0.96 and VDOP=2.46, indicating a small rate of accuracy degradation, open space in the zenith direction, and a suitable condition for positioning (○).
[0050] Furthermore, as shown in Figure 6, the GAL receiver has a targeting count of 8 satellites in the GAL positioning system. In this case, HDOP=0.93 and VDOP=1.30, indicating a small rate of accuracy degradation and even distribution. However, due to the low number of acquired satellites, the condition remains suitable for positioning (○).
[0051] Furthermore, as shown in Figure 6, the BDS receiver has a targeting count of 20 satellites in the BDS positioning system. In this case, HDOP=0.67 and VDOP=1.02, the accuracy degradation rate is small, and although the satellite configuration is aligned from the southwest, the number of acquired satellites is large, making it a more suitable condition for positioning (◎).
[0052] As explained above, even with the same satellite configuration, increasing the elevation angle and narrowing the satellite acquisition range in order to improve positioning accuracy can lead to the inability to acquire satellites, potentially resulting in a decrease in positioning accuracy. Therefore, immediately after switching positioning modes, it is desirable to set the elevation angle to the lowest value to allow for the acquisition of a larger number of satellites.
[0053] Figure 7 is a processing flowchart (part 2) of the embodiment. The system initiates a switch from standalone positioning to relative positioning (step S15), and once it reaches a state of continuous relative positioning (step S31), it is determined again whether the conditions for transitioning to relative positioning are met (step S32). In the determination in step S32, if it is determined that the relative positioning transition conditions are met again (step S32; Yes), the process returns to step S31 to maintain the relative positioning continuation state. If, in the judgment in step S32, it is determined that the relative positioning transition conditions are insufficient (step S32; No), the system switches from relative positioning to standalone positioning (step S33). Then, during standalone positioning, it is determined whether or not a state of excessive error in standalone positioning has occurred (step S34). In the determination in step S34, if no excessive error occurs during standalone positioning (step S34; No), standalone positioning is maintained, and the process is returned to step S32 to perform the above-described processing. In the determination in step S34, if an excessive error condition occurs during standalone positioning (step S34; Yes), the system switches from standalone positioning to autonomous positioning (step S35), and the process proceeds to step S41 (see Figure 8).
[0054] Figure 8 is a processing flowchart (part 3) of the embodiment. On the other hand, in the judgment of step S12 in Figure 2, if two or more of the conditions for transitioning to autonomous positioning are met (step S22; Yes), it means that an excessive error state has been reached in autonomous positioning, so the switching from standalone positioning to autonomous positioning is initiated (step S16), the transition to autonomous positioning is completed, and the process in Figure 8 is initiated to continue autonomous positioning (step S41).
[0055] During autonomous positioning, it is determined whether or not a state of excessive error in autonomous positioning has occurred (step S42). More specifically, for example, in the autonomous positioning state, if two or more of the following autonomous positioning transition conditions (1) to (4) are met, the system is in an error-excessive state, and therefore, it is determined whether or not two or more of the autonomous positioning transition conditions have been met. (1)Estimated distance error (ΔL)≦0.05m (2) PACC 3D ≤ 0.5m (3) PACC 3D% ≤ 2% (41) Number of satellites used for positioning ≥ 15 The number of conditions and settings for the transitions can be changed as needed.
[0056] In the determination in step S42, if the error is not excessive (step S42; No), the process returns to step S41 and autonomous positioning continues. In the determination in step S42, if the error is excessive (step S42; Yes), it is undesirable to continue autonomous positioning, so the system switches from autonomous positioning to standalone positioning (step S43).
[0057] Furthermore, it is determined whether the conditions for transitioning to relative positioning have been met during standalone positioning (step S44). The criteria for this determination are the same as those for step S14 described above.
[0058] In the determination in step S44, if the relative positioning transition conditions are not met (step S44; No), the process returns to step S42 to maintain the standalone positioning state and perform the described processing.
[0059] In the determination in step S44, if the relative positioning transition conditions are met (step S44; Yes), the system switches from standalone positioning to relative positioning (step S45), and the process returns to step S31 in Figure 7, and the above-described processing is performed.
[0060] Next, returning to the explanation of Figure 2, we will describe the case where the previous positioning was autonomous positioning at startup (when the power is turned on). If the previous positioning was autonomous positioning at startup (when power is turned on), autonomous positioning is started (step S17), and the process proceeds to step S41 in Figure 8, continuing autonomous positioning (step S41). The following steps S42 to S44 described above will be performed.
[0061] As described above, the positioning device of the embodiment monitors whether the positioning method (positioning mode) is near the switching condition when performing positioning using any of the positioning methods (positioning modes) of standalone positioning, autonomous measurement, or relative positioning. By switching to a more stable positioning method earlier and suppressing the switching frequency, the processing load is reduced, and a decrease in position measurement accuracy due to unstable conditions can be suppressed.
[0062] In other words, it is possible to control the switching frequency in situations where the reception environment for positioning radio waves from artificial satellites tends to be unstable, thereby ensuring more stable position measurement accuracy.
[0063] Next, we will explain in more detail the process for determining excessive errors in standalone positioning or relative positioning. Figure 9 is a conceptual diagram illustrating the positioning status. In Figure 9, position PS0 is the positioning position during the previous positioning, and position PS1 is the true positioning position during the current positioning. Furthermore, the positioning location PSe is the positioning location obtained under conditions of excessive error.
[0064] Furthermore, L1 represents the vector length from the previous positioning position PS0 to the true positioning position PS1, and L2 represents the length (travel length, travel distance) from the previous positioning position PS0 to the positioning position PSe obtained under the excessive error condition. The process for determining the state of excessive error in the above situation will now be explained.
[0065] Figure 10 is a flowchart (part 1) for determining the state of excessive error. First, a predetermined number of GNSS data points are acquired and temporarily stored (step S51). For example, if GNSS data is acquired every 0.1 seconds, then, for instance, 10 GNSS data points representing 1 second would be stored.
[0066] Next, it is determined whether a predetermined number of GNSS data points (10 in the example above) have been acquired (step S52). If, in the determination in step S52, a predetermined number of GNSS data has not yet been acquired (step S52; No), the process proceeds back to step S51. In the determination in step S52, if a predetermined number of GNSS data can be obtained (step S52; Yes), the vector length L2 is calculated from the coordinate difference (X,Y) in the ECEF (Geocentric Earth Fixed Coordinate System) between the last obtained GNSS data and the GNSS data obtained immediately before it (in the above example, the GNSS data obtained 0.1s earlier) (step S53).
[0067] Obtain GNSS speed data (train speed data) Speed [m / s] (step S54). The travel length (distance) L1 of the railway vehicle is calculated based on the train speed and the positioning time interval (0.1s = 100ms in the example above) (step S55).
[0068] More specifically, the following equation holds true. Distance L1 [m] = Speed [m / s] × 0.1 [s] The difference dL between the movement length L1 and the vector length L2 is calculated (step S56). More specifically, as shown in Figure 9, the following equation holds: Difference dL=L2-L1
[0069] Next, if the difference is greater than a predetermined first threshold, that is, if the distance error between the measured distance and the actual distance is unacceptably large, the first flag FLG1 is set to "1" (step S57). Next, the current 3D position accuracy PACC 3D is obtained (step S58).
[0070] In this case, the 3D position accuracy PACC 3D is expressed by the following equation, where the horizontal position accuracy is hACC and the vertical position accuracy is vACC. PACC 3D = √(hACC) 2 +vACC 2 )
[0071] If the acquired current 3D position accuracy PACC 3D is greater than a predetermined second threshold, that is, if the accuracy of the 3D position accuracy PACC 3D is lower than a predetermined value, the second flag FLG2 is set to "1" (step S59).
[0072] Next, the average value of the 3D position accuracy PACC 3D corresponding to a predetermined number of acquired GNSS data points over a predetermined time period (in the example below, 9 samples over a period of -900ms to -100ms) is calculated. ave Calculate (step S60).
[0073]
number
[0074]
number
[0075] If the calculated rate of change of the current 3D position accuracy PACC 3D, ratio PACC 3D, is greater than a predetermined third threshold, the third flag FLG3 is set to "1" (step S62).
[0076] Figure 11 is a flowchart (part 2) for determining the state of excessive error. Next, the number of satellites used for the current positioning is obtained (step S63). If the number of acquired satellites is less than a predetermined fourth threshold, the fourth flag FLG4 is set to "1" (step S64).
[0077] Furthermore, the number of flags among the first flag FLG1 to the fourth flag FLG4 that are set to "1" is counted (step S65). Then, it is determined whether the number of counted flags is equal to or greater than a predetermined count threshold (step S66). In other words, it is determined whether the system is in a state unsuitable for GNSS positioning.
[0078] In the determination in step S66, if the number of counted flags is less than a predetermined count threshold (step S66; No), it is determined whether or not GNSS positioning (standalone positioning) was performed a predetermined time earlier (100 ms earlier in the example in Figure 11) (step S67). In the determination in step S67, if GNSS positioning (standalone positioning) was performed prior to the predetermined time, the GNSS positioning (standalone positioning) is maintained, and the process is returned to step S51 (see Figure 10), and the above-described process is repeated. In the determination in step S67, if GNSS positioning (standalone positioning) was not performed prior to the predetermined time (step S67; No), that is, if autonomous positioning was performed prior to the predetermined time, then the system switches from autonomous positioning to GNSS positioning (standalone positioning) (step S68).
[0079] Furthermore, in the determination in step S66, if the number of counted flags is greater than or equal to a predetermined count threshold (step S66; Yes), that is, if the receiver is not in a state suitable for GNSS positioning, it is determined whether the receiver's operating mode is in a mode other than fix mode (step S69).
[0080] In the determination in step S69, if the receiver's operating mode is not a mode other than fix mode, that is, if the receiver's operating mode is fix mode, it is determined whether the number of counted flags has exceeded a predetermined threshold for two consecutive times (step S70). In other words, it is determined whether the receiver is in a state that is not suitable for GNSS positioning by chance, or whether it is actually in a state that is not suitable for GNSS positioning.
[0081] In the determination in step S70, if the number of counted flags has exceeded a predetermined threshold for the first time (step S70; No), the process returns to step S51 (see Figure 10) and the above process is repeated. In the determination of step S, if the number of counted flags exceeds a predetermined threshold for two consecutive times, it is determined that the system is not actually suitable for GNSS positioning, and the system switches to autonomous positioning.
[0082] As described above, the error overload detection process of this embodiment can reliably determine whether or not to switch positioning modes depending on the positioning mode currently being used, and if so, which positioning mode is more preferable to switch to. This effectively reduces the switching frequency, thereby reducing the processing load and suppressing the decrease in position measurement accuracy due to unstable conditions. Therefore, it is possible to ensure more stable position measurement accuracy while reducing the processing load.
[0083] The position measurement calculation processing unit in this embodiment functions as a control unit and includes a control device such as a CPU, a storage device such as ROM (Read Only Memory) or RAM, and an external storage device such as an HDD or SSD, thus having a hardware configuration that utilizes a normal computer.
[0084] The program executed by the position measurement calculation processing unit of this embodiment is provided as an installable or executable file, recorded on a computer-readable recording medium such as a USB memory stick, an SSD (Solid State Drive), or a DVD (Digital Versatile Disk).
[0085] Furthermore, the program executed by the position measurement calculation processing unit of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Alternatively, the program executed by the position measurement calculation processing unit of this embodiment may be provided or distributed via a network such as the Internet. Alternatively, the program of this embodiment may be provided pre-installed in a ROM or the like.
[0086] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]
[0087] 10 Positioning Systems 21. First Satellite Positioning Unit 22 Second Satellite Positioning Unit 23. Autonomous positioning unit 24 Position Measurement Calculation Processing Unit (Control Unit) DP1 First Satellite Positioning Data DP2 2nd Satellite Positioning Results Data DS (Digital Steering) Positioning Result Data FLG1 First Flag FLG2 2nd Flag FLG3 3rd Flag FLG4 4th Flag L1 Movement length L2 vector length PS0, PS1, PSe positioning location Speed train speed TR Railway Vehicles dL difference
Claims
1. A mobile positioning system mounted on a mobile object and used to determine the position of the mobile object, A first satellite positioning unit that receives positioning radio waves from an artificial satellite and determines the first position of the moving object, A second satellite positioning unit receives positioning radio waves from an artificial satellite and determines the second position of the moving object, An autonomous positioning unit that performs autonomous positioning of the third position of the moving body, The system includes a control unit that exclusively selects one of the following positioning modes: a standalone positioning mode in which the position of the moving object is determined by either the first satellite positioning unit or the second satellite positioning unit; a relative positioning mode in which the position of the moving object is determined by both the first and second satellite positioning units; and an autonomous positioning mode in which the position of the moving object is determined by the autonomous positioning unit. The control unit prohibits direct transitions between the autonomous positioning mode and the relative positioning mode, and when switching positioning modes between the standalone positioning mode and the relative positioning mode, it sets the elevation angle to a predetermined minimum value so that the number of satellites to be acquired can be increased, and sets the received signal strength of the satellite radio waves of the satellites to be acquired to a predetermined minimum value, causing the first satellite positioning unit and the second satellite positioning unit to acquire satellites. Mobile positioning system.
2. When the control unit transitions from the autonomous positioning mode or the relative positioning mode to another positioning mode, it transitions to the standalone positioning mode. The mobile positioning system according to claim 1.
3. The control unit switches to a positioning mode when at least some of the switching conditions in the source positioning mode are met and all of the switching conditions in the destination positioning mode are met. The mobile positioning system according to claim 1.
4. A mobile positioning switching method is performed in a mobile positioning system mounted on a mobile body and used to determine the position of the mobile body, comprising: a first satellite positioning unit that receives positioning radio waves from an artificial satellite and determines the first position of a mobile body; a second satellite positioning unit that receives positioning radio waves from an artificial satellite and determines the second position of the mobile body; and an autonomous positioning unit that performs autonomous positioning of the third position of the mobile body, the system being used to determine the position of the mobile body, The system has a standalone positioning mode in which the position of the moving object is determined by either the first satellite positioning unit or the second satellite positioning unit, a relative positioning mode in which the position of the moving object is determined by both the first and second satellite positioning units, and an autonomous positioning mode in which the position of the moving object is determined by the autonomous positioning unit, and a process for exclusively selecting one of these positioning modes, Direct transitions between the autonomous positioning mode and the relative positioning mode are prohibited. When switching positioning modes between the standalone positioning mode and the relative positioning mode, the elevation angle is set to a predetermined minimum value to increase the number of satellites to be acquired, and the reception strength of the satellite radio waves of the satellites to be acquired is set to a predetermined minimum value, causing the first satellite positioning unit and the second satellite positioning unit to acquire satellites. A mobile positioning switching method equipped with the following features.