A railway-specific satellite positioning test method and system for observation-restricted scenarios

Abstract

The present invention discloses a railway-specific satellite positioning test method and system for observation-restricted scenarios, the method comprising: establishing a restricted trajectory interval; obtaining the train IMU position and the first-level train GNSS position; determining whether the train passes through the restricted trajectory interval during the test, and if there is observation restriction, filtering out the valid first-level train GNSS position based on the position residual and constructing the second-level train GNSS position based on it; calculating the final position of the train by the train IMU position and the second-level train GNSS position; completing the trajectory consistency diagnosis by the final position of the train and the position of the positioning tester. The present invention reduces the real-time computing power demand by combining offline and online methods, designs a restriction monitoring algorithm to analyze the observation restriction situation around the train, and designs a GNSS positioning signal optimization algorithm to reduce abnormal signal interference, all of which effectively improve the accuracy of the test method.

Description

Technical Field

[0001] The present invention relates to the field of positioning test technology, and in particular to a railway-specific satellite positioning test method and system for observation-restricted scenarios. Background Art

[0002] With the continuous development of public transportation technology, railway transportation, with its speed and convenience, has become an indispensable means of transportation in today's society, playing an irreplaceable role in freight transportation and personnel exchanges. To ensure timely monitoring of train movements and ensure the safety and efficiency of railway operations, railway satellite positioning technology has gradually become a focus of research researchers and frontline workers.

[0003] Existing railway satellite positioning technologies mostly rely on GNSS or Beidou signals for train positioning. While traditional satellite positioning test methods can achieve basic positioning testing, trains often pass through scenarios with limited observation. In these scenarios, satellite signals are subject to obstruction and multipath errors. Due to the high speeds of trains, these issues are difficult to detect in a timely manner, resulting in significant positioning deviations and serious safety hazards. Therefore, a new railway-specific satellite positioning test method is needed to address these issues. Summary of the Invention

[0004] The present invention provides a railway-specific satellite positioning test method and system for observation-restricted scenarios, so as to solve the technical problems of difficulty in timely identifying observation-restricted scenarios, poor real-time positioning test performance, and large deviation.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a railway-specific satellite positioning test method for observation-restricted scenarios, comprising the following steps:

[0007] S1. Obtain the height values ​​of the train track and the surrounding environment of the train track, divide the train track into sections, calculate the restriction of each track section based on the height values ​​within the track section, obtain the restricted track section and upload it to the positioning tester;

[0008] S2. Obtain the train IMU position through the train IMU, obtain the first-level train GNSS position through the train GNSS receiver, and upload the train IMU position and the first-level train GNSS position to the positioning tester;

[0009] S3. Initialize the positioning test period. Based on the train's current position and the restricted trajectory intervals passed by the train during the positioning test period, determine whether the train has passed through an observation-restricted scene. If the train has not passed through an observation-restricted scene, calculate the train's final position using the train's IMU position and the first-level train GNSS position, and execute step S6 to determine the trajectory consistency. Otherwise, execute step S4 to optimize the GNSS signal.

[0010] S4. Calculate the position residual between the train IMU position and the primary train GNSS position during the positioning test period, select the valid primary train GNSS position based on the position residual, and construct the secondary train GNSS position based on it;

[0011] S5. The final train position is calculated based on the train IMU position and the secondary train GNSS position;

[0012] S6. Obtain the position of the positioning tester, and complete the trajectory consistency judgment based on the final position of the train and the position of the positioning tester during the positioning test period.

[0013] Furthermore, the step S1 includes:

[0014] S11, obtaining the height value of the train running track and the environment around the train running track;

[0015] S12, dividing the trajectory into partitions:

[0016] The train track is partitioned according to the specifications of a meters * a meters, where a is greater than the width of the train. Each track partition is based on the train track it contains as the central axis. For the track part that does not meet the specifications of a meters * a meters, it is calculated as a complete track partition to obtain the track partition G:

[0017] G={G1,...,G i ,...,G n}

[0018] Among them: G1 represents the first trajectory partition, G i represents the i-th trajectory partition, G n represents the nth trajectory partition, where n represents the number of trajectory partitions;

[0019] S13, dividing the trajectory into sub-partitions:

[0020] Each track partition is further divided into 9 track sub-partitions of the same size according to the 3*3 specification. The track sub-partitions are numbered 1-9 in the order of first along the width direction of the train and then along the length direction of the train. The expression of the i-th track partition is as follows:

[0021]

[0022] in, Indicates the maximum height value of the first track sub-partition in the i-th track partition, represents the maximum height value of the jth track sub-partition within the i-th track partition, represents the maximum height value of the 9th track sub-partition within the i-th track partition;

[0023] The 1st, 4th, and 7th track subpartitions are considered as the first side, the 2nd, 5th, and 8th track subpartitions are considered as the second side, and the 3rd, 6th, and 9th track subpartitions are considered as the third side;

[0024] S14. Calculate the height of the trajectory sub-partition:

[0025] Calculate trajectory partition G i Average height of the first side Average height of the second side and the average height of the third side The expression is as follows:

[0026]

[0027] S15. Judgment of first and third side restrictions:

[0028] Initialize height threshold Compare and The size of the value is based on the larger value and the height threshold The size relationship is used to determine the restricted conditions of the first and third sides. The expressions are as follows:

[0029]

[0030] in, represents the degree of restriction of the first and third sides in the i-th trajectory partition;

[0031] when When , it means that the GNSS observation is limited in the trajectory sub-area on the first side or the third side. When , it means that GNSS observations in the trajectory sub-area on the first or third side are not restricted;

[0032] S16, second side restriction judgment:

[0033] Initialize height difference threshold Compute the difference in the average height of the second side between adjacent trajectory bins:

[0034] ΔG={ΔG1,...,ΔG i ,...,ΔG n-1}

[0035]

[0036] Based on the obtained difference and the height difference threshold The relationship between the size of the second side is used to determine the limitation of the second side. The expression is as follows:

[0037]

[0038] in, represents the degree of restriction of the second side within the i-th trajectory partition;

[0039] when When , it means that the GNSS observation is limited in the trajectory sub-area on the second side. When , it means that GNSS observations in the trajectory sub-area on the second side are not restricted;

[0040] S17, Constrained Integration Calculation:

[0041] Calculate the restricted degree of the i-th trajectory partition The expression is as follows:

[0042]

[0043] when When it is equal to 1 or 2, it means that the GNSS observation is limited in the i-th trajectory partition, and there is an observation-limited scenario. When it is equal to 0, it means that GNSS observations are not restricted in the i-th trajectory partition and there is no observation restriction scenario;

[0044] S18, restricted trajectory interval:

[0045] By calculating the restriction of each trajectory partition, the restricted trajectory interval T is obtained. 1,2,3 :

[0046]

[0047] in, They represent the degree of restriction of different trajectory partitions respectively;

[0048] S19, the restricted trajectory interval F 1,2,3 Will be uploaded to the positioning tester.

[0049] It should be noted that the train running track refers to the fixed running track of the train and is obtained offline. During the positioning test, the train runs along this track, so the observation restrictions around the train running track can be analyzed in advance; the height value of the environment around the train running track is obtained through satellite maps. The satellite maps can use existing digital maps, such as Amap, Baidu Map, etc. The use of satellite maps can reduce the workload and complexity of preliminary preparation work.

[0050] The track partition is divided into a first side, a second side, and a third side. The first and third sides are used to determine whether there are tall objects in the surrounding environment of the train track. The second side is located near the center of the track and is used to determine whether the train track passes through a tunnel. The value of a can be selected based on train parameters and actual test requirements.

[0051] The entire calculation process for the restricted degree and restricted trajectory interval is completed offline before the positioning test. This can reduce the amount of online calculations during the positioning test and improve the real-time performance of the positioning test. By utilizing the existing train track and existing satellite maps, the real-time and accuracy of observing restricted scenes can be improved through the combination of multiple sources of information. The offline and online mentioned in this invention refer to before and during the positioning test, respectively.

[0052] Furthermore, the step S2 includes:

[0053] S21. Get the train IMU position:

[0054] The train IMU is located in the middle of the train, and the train IMU position P is calculated based on the train IMU signal. IMU :

[0055]

[0056] Where m represents the number of train IMU signals during the positioning test period. Indicates the train IMU position corresponding to the i-th train IMU signal;

[0057] S22. Obtain the GNSS position of the first-level train:

[0058] Two GNSS receivers are located at the head and tail of the train respectively. The positions of the two GNSS receivers are obtained by receiving GNSS signals:

[0059]

[0060] Where J1 represents the GNSS receiver at the front of the train, J2 represents the GNSS receiver at the rear of the train, and u represents the number of GNSS signals received by the GNSS receiver during the positioning test period. represents the position of J1 when it receives the i-th GNSS signal, represents the position of J2 when it receives the i-th GNSS signal;

[0061] Depend on and Calculate the GNSS position of the first-level train

[0062]

[0063] in, represents the train position corresponding to the i-th GNSS signal;

[0064] S23. Upload the train IMU position and the first-level train GNSS position to the positioning tester.

[0065] It should be noted that the train IMU is located in the middle of the train and in the middle of the two GNSS receivers, and the height of the train IMU and the two receivers are consistent. The position of the train IMU is calculated by integrating the linear acceleration and angular acceleration.

[0066] By combining the GNSS signals from two receivers for calculation, the error caused by a single receiver failure can be reduced, thereby avoiding systematic errors in the calculation process and improving the accuracy of the test method.

[0067] Furthermore, step S3 includes:

[0068] S31. Determine the restricted track section that the train passes through:

[0069] Initialize the positioning test time period T, obtain the average speed v of the train, and calculate the length of the test track interval:

[0070] L=λ*T*v

[0071] Where λ represents the length coefficient;

[0072] Calculate the number of trajectory partitions:

[0073] n=L / a

[0074] Based on the current position of the train and the number of track partitions, determine the restricted track intervals that the train passes through during the positioning test period

[0075] S32. Determine whether the train passes through an observation-restricted scene based on the restricted trajectory interval:

[0076] When all the restricted values ​​within the restricted trajectory interval are zero, it means that during the positioning test period, the scenes passed by the train are all unrestricted observation scenes. The final position of the train is calculated by the first-level train GNSS position and the train IMU position, and step S6 is executed to determine the trajectory consistency.

[0077] When a non-zero value exists in the restricted trajectory interval, it indicates that during the positioning test period, an observation restricted scene exists in the scene where the train passes, and step S4 is executed to optimize the GNSS signal.

[0078] It should be noted that the average speed v of the train refers to the average speed of the last train running along the same track; by combining historical data of train operation and offline information, it is possible to quickly determine whether there is an observation-restricted scenario.

[0079] The length coefficient λ is set to avoid the restricted trajectory interval being too small due to the train speed being higher than the average speed during the positioning test phase. It is an empirical value and can also take a value in the range of [1,1.5]. The selection of this coefficient depends on the test conditions. If the restricted trajectory interval of the last test is smaller than the actual operating trajectory, the coefficient is increased. If the restricted trajectory interval of the last test is greater than or equal to the actual operating trajectory, the coefficient remains unchanged.

[0080] Furthermore, the step S4 includes:

[0081] S41. Calculate the position residual between the train IMU position and the first-level train GNSS position:

[0082] At each moment, the train IMU collects a train IMU signal and the GNSS receiver receives a GNSS signal;

[0083] Get the train IMU position for t consecutive moments during the current positioning test period:

[0084]

[0085] Where t is an integer and is less than T;

[0086] Get the GNSS position of the first-level train for t consecutive moments during the current positioning test period:

[0087]

[0088] Due to the existence of observation-restricted scenarios, the train position calculated by the GNSS signal has deviations. Therefore, the set of position residuals ΔP between the train IMU position and the first-level train GNSS position at t consecutive moments in the current positioning test period is calculated, where the position residual ΔP at the i-th moment is i The expression is as follows:

[0089]

[0090] S42. Optimize the GNSS position of first-level trains:

[0091] Calculate the probability Pr that the GNSS position of the i-th first-level train is a valid GNSS signal based on the position residual i , the expression is as follows:

[0092] Pr i =[(ΔP)max -ΔP i ] / [(ΔP) max -(ΔP) min ]

[0093] Where (ΔP) max Indicates the maximum value in ΔP, (ΔP) min represents the minimum value in ΔP;

[0094] Initialize the probability threshold α and mark the GNSS position of the first-level train based on the relationship between the obtained probability and the probability threshold:

[0095] When Pr i ≥α, the GNSS position of the i-th first-level train is marked as a valid GNSS signal. i <α, the GNSS position of the i-th first-level train is marked as an invalid GNSS signal;

[0096] S43. Reconstruct the secondary train GNSS position using all valid GNSS signals.

[0097] Furthermore, the step S5 includes:

[0098] Initialize the adjustment coefficients β and γ, where β + γ = 1;

[0099] The final position of the train is calculated by the train IMU position and the secondary train GNSS position, where the final position of the i-th train is The expression is as follows:

[0100]

[0101] in, represents the GNSS position of the i-th secondary train.

[0102] It should be noted that by selecting a suitable adjustment coefficient, the train IMU position and the secondary train GNSS position are integrated to ensure that the final train position, i.e., the train positioning test trajectory, is accurate and reliable.

[0103] Furthermore, step S6 includes:

[0104] S61. Obtain the position P of the positioning tester C :

[0105]

[0106] Where w represents the number of secondary train GNSS positions;

[0107] S62. Trajectory consistency judgment:

[0108] During the positioning test period, the cumulative error e between the final position of the train and the position of the positioning tester is calculated, and the expression is as follows:

[0109]

[0110] Initialize the cumulative error threshold ε, and output the trajectory consistency judgment result based on the relationship between the obtained cumulative error and the cumulative error threshold:

[0111] When e≥ε, it means that the train positioning test track is consistent with the actual train track and the satellite positioning is accurate. When e<ε, it means that the train positioning test track is inconsistent with the actual train track and the satellite positioning is inaccurate.

[0112] It should be noted that when conducting satellite positioning tests, a benchmark, that is, an accurate standard value, is required for comparison and judgment. The location of the positioning tester here can play the above role; the positioning tester is located in the middle of the train, and it calculates the exact position of the train based on known data such as the initial position of the train, the train speed, and the train acceleration. The collection of these positions is the actual trajectory of the train. These accurate position information can be used to determine whether the GNSS signal positioning is accurate.

[0113] The present invention also provides a railway-specific satellite positioning test system for observation-restricted scenarios, comprising the following modules:

[0114] Offline data processing module: obtains the height values ​​of the train track and the surrounding environment of the train track, divides the train track into partitions, calculates the restriction of each track partition based on the height values ​​within the track partition, obtains the restricted track interval and uploads it to the positioning tester;

[0115] Real-time data acquisition module: obtains the train IMU position through the train IMU, obtains the first-level train GNSS position through the train GNSS receiver, and uploads the train IMU position and the first-level train GNSS position to the positioning tester;

[0116] Restricted scenario judgment module: Initializes the positioning test period and determines whether the train has passed through an observation-restricted scenario based on the train's current position and the restricted trajectory interval passed by the train during the positioning test period. If the train has not passed through an observation-restricted scenario, the trajectory consistency judgment module is run; otherwise, the GNSS signal optimization module is run.

[0117] GNSS signal screening module: Calculates the position residual between the train IMU position and the first-level train GNSS position during the positioning test period, and based on the position residual, selects the valid first-level train GNSS position and constructs the second-level train GNSS position.

[0118] Trajectory consistency judgment module: The final train position is calculated by the train IMU position and the first-level train GNSS position, or the final train position is calculated by the train IMU position and the second-level train GNSS position, and the position of the positioning tester is obtained. The trajectory consistency judgment is completed by the final train position and the positioning tester position within the positioning test time period.

[0119] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0120] 1. The present invention adopts a combination of offline and online methods to realize the railway-specific satellite positioning test function for observation-restricted scenarios. After determining the running track of the railway train, a limitation monitoring algorithm is designed, and the limitation is calculated through the train running track and satellite map, and then the restricted track interval is established offline. When it is found that the train passes through the restricted track interval within the positioning test time period, a GNSS signal optimization algorithm based on position residual is further designed, and the track consistency judgment is completed based on the final position of the train obtained after screening. Compared with the traditional full-time online testing method, the technical solution of the present invention reduces the computing power loss of online resources, has stronger real-time performance, can improve test efficiency, and is conducive to timely detection of trains passing through observation-restricted scenarios, thereby improving test accuracy.

[0121] 2. The present invention designs a limitation monitoring algorithm to monitor the running track of the train. The train running track is first partitioned, and then each track partition is divided into track sub-partitions arranged in a nine-square grid and divided into a first side, a second side, and a third side. The height values ​​of the first side and the third side are used to determine whether there are tall objects near the train track. The height value of the second side is used to determine whether the train track passes through a tunnel, and then the limitation is calculated to obtain the limited track interval. The present invention can more accurately analyze the observation limitation of the scene around the track through the division of the track sub-areas, thereby improving the accuracy of the testing method.

[0122] 3. Aiming at the situation where a train passes through a scene with restricted observation, the present invention designs a GNSS signal optimization algorithm based on the residual between the train IMU position and the first-level train GNSS position. The effective probability of each first-level train GNSS position is calculated through the position residual, and the second-level train GNSS position is reconstructed from the effective first-level train GNSS position. The second-level train GNSS position and the train IMU position are integrated to obtain the final train position for trajectory consistency judgment. The present invention can eliminate the interference caused by receiving abnormal GNSS signals in the scene with restricted observation. Introducing the IMU position information for screening can improve the richness of sensor information and further improve the accuracy of the test method. BRIEF DESCRIPTION OF THE DRAWINGS

[0123] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0124] Figure 1 This is a flowchart of a railway-specific satellite positioning test method for observation-restricted scenarios provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0125] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0126] Example 1

[0127] This embodiment will describe the method of the present invention in more detail with reference to the accompanying drawings. Figure 1 As shown, a railway-specific satellite positioning test method for observation-restricted scenarios includes:

[0128] S1. Obtain the height values ​​of the train track and the surrounding environment of the train track, divide the train track into sections, calculate the restriction of each track section based on the height values ​​within the track section, obtain the restricted track section and upload it to the positioning tester;

[0129] S2. Obtain the train IMU position through the train IMU, obtain the first-level train GNSS position through the train GNSS receiver, and upload the train IMU position and the first-level train GNSS position to the positioning tester;

[0130] S3. Initialize the positioning test period. Based on the train's current position and the restricted trajectory intervals passed by the train during the positioning test period, determine whether the train has passed through an observation-restricted scene. If the train has not passed through an observation-restricted scene, calculate the train's final position using the train's IMU position and the first-level train GNSS position, and execute step S6 to determine the trajectory consistency. Otherwise, execute step S4 to optimize the GNSS signal.

[0131] S4. Calculate the position residual between the train IMU position and the primary train GNSS position during the positioning test period, select the valid primary train GNSS position based on the position residual, and construct the secondary train GNSS position based on it;

[0132] S5. The final train position is calculated based on the train IMU position and the secondary train GNSS position;

[0133] S6. Obtain the position of the positioning tester, and complete the trajectory consistency judgment based on the final position of the train and the position of the positioning tester during the positioning test period.

[0134] Specifically,

[0135] The step S1 comprises:

[0136] S11, obtaining the height value of the train running track and the environment around the train running track;

[0137] S12, dividing the trajectory into partitions:

[0138] The train track is partitioned into 15m*15m sections, where a is greater than the train width. Each track section is centered on the train track it contains. For the last section that does not meet the 15m*15m specification, it is calculated as a complete track section to obtain the track section G:

[0139] G={G1,...,G i ,...,G n}

[0140] Among them: G1 represents the first trajectory partition, G i represents the i-th trajectory partition, G n represents the nth trajectory partition, where n represents the number of trajectory partitions;

[0141] S13, dividing the trajectory into sub-partitions:

[0142] Each track partition is further divided into 9 track sub-partitions of the same size according to the specifications of 3*3 (i.e. 5m*5m). The track sub-partitions are numbered 1-9 in the order of first along the width of the train and then along the length of the train. The expression of the i-th track partition is as follows:

[0143]

[0144] in, Indicates the maximum height value of the first track sub-partition in the i-th track partition, represents the maximum height value of the jth track sub-partition within the i-th track partition, represents the maximum height value of the 9th track sub-partition within the i-th track partition;

[0145] The 1st, 4th, and 7th track subpartitions are considered as the first side, the 2nd, 5th, and 8th track subpartitions are considered as the second side, and the 3rd, 6th, and 9th track subpartitions are considered as the third side;

[0146] S14. Calculate the height of the trajectory sub-partition:

[0147] Calculate trajectory partition Gi Average height of the first side Average height of the second side and the average height of the third side The expression is as follows:

[0148]

[0149] S15. Judgment of first and third side restrictions:

[0150] Initialize height threshold Compare and The size of the value is based on the larger value and the height threshold The size relationship is used to determine the restricted conditions of the first and third sides. The expressions are as follows:

[0151]

[0152] in, represents the degree of restriction of the first and third sides in the i-th trajectory partition;

[0153] when When , it means that the GNSS observation is limited in the trajectory sub-area on the first side or the third side. When , it means that GNSS observations in the trajectory sub-area on the first or third side are not restricted;

[0154] S16, second side restriction judgment:

[0155] Initialize height difference threshold Compute the difference in the average height of the second side between adjacent trajectory bins:

[0156] ΔG={ΔG1,...,ΔG i ,...,ΔG n-1}

[0157]

[0158] Based on the obtained difference and the height difference threshold The relationship between the size of the second side is used to determine the limitation of the second side. The expression is as follows:

[0159]

[0160] in, represents the degree of restriction of the second side within the i-th trajectory partition;

[0161] when When , it means that the GNSS observation is limited in the trajectory sub-area on the second side. When , it means that GNSS observations in the trajectory sub-area on the second side are not restricted;

[0162] S17, Constrained Integration Calculation:

[0163] Calculate the restricted degree of the i-th trajectory partition The expression is as follows:

[0164]

[0165] when When it is equal to 1 or 2, it means that the GNSS observation is limited in the i-th trajectory partition, and there is an observation-limited scenario. When it is equal to 0, it means that GNSS observations are not restricted in the i-th trajectory partition and there is no observation restriction scenario;

[0166] S18, restricted trajectory interval:

[0167] By calculating the restriction of each trajectory partition, the restricted trajectory interval F is obtained. 1,2,3 :

[0168]

[0169] in, They represent the degree of restriction of different trajectory partitions respectively;

[0170] S19, the restricted trajectory interval F 1,2,3 Will be uploaded to the positioning tester.

[0171] The step S2 comprises:

[0172] S21. Get the train IMU position:

[0173] The train IMU is located in the middle of the train, and the train IMU position P is calculated based on the train IMU signal. IMU :

[0174]

[0175] Where m represents the number of train IMU signals during the positioning test period. Indicates the train IMU position corresponding to the i-th train IMU signal;

[0176] S22. Obtain the GNSS position of the first-level train:

[0177] Two GNSS receivers are located at the head and tail of the train respectively. The positions of the two GNSS receivers are obtained by receiving GNSS signals:

[0178]

[0179] Where J1 represents the GNSS receiver at the front of the train, J2 represents the GNSS receiver at the rear of the train, and u represents the number of GNSS signals received by the GNSS receiver during the positioning test period. represents the position of J1 when it receives the i-th GNSS signal, represents the position of J2 when it receives the i-th GNSS signal;

[0180] Depend on and Calculate the GNSS position of the first-level train

[0181]

[0182] in, represents the train position corresponding to the i-th GNSS signal;

[0183] S23. Upload the train IMU position and the first-level train GNSS position to the positioning tester.

[0184] The step S3 comprises:

[0185] S31. Determine the restricted track section that the train passes through:

[0186] Initialize the positioning test time period T, obtain the average speed v of the train, and calculate the length of the test track interval:

[0187] L=1.15*T*v

[0188] Calculate the number of trajectory partitions:

[0189] n=L / 15

[0190] Based on the current position of the train and the number of track partitions, determine the restricted track intervals that the train passes through during the positioning test period

[0191] S32. Determine whether the train passes through an observation-restricted scene based on the restricted trajectory interval:

[0192] If all the restricted values ​​within the restricted trajectory interval are zero, it means that during the positioning test period, the scenes passed by the train are all unrestricted observation scenes. The final position of the train is calculated by the first-level train GNSS position and the train IMU position, and step S6 is executed to determine the trajectory consistency.

[0193] If there is a non-zero value of the constraint within the restricted trajectory interval, it means that during the positioning test period, there is an observation-restricted scene in the scene where the train passes, and step S4 is executed to optimize the GNSS signal.

[0194] Furthermore, the step S4 includes:

[0195] S41. Calculate the position residual between the train IMU position and the first-level train GNSS position:

[0196] At each moment, the train IMU collects a train IMU signal and the GNSS receiver receives a GNSS signal;

[0197] Get the train IMU position for t consecutive moments during the current positioning test period:

[0198]

[0199] Where t is an integer and is less than T;

[0200] Get the GNSS position of the first-level train for t consecutive moments during the current positioning test period:

[0201]

[0202] Due to the existence of observation-restricted scenarios, the train position calculated by the GNSS signal has deviations. Therefore, the set of position residuals ΔP between the train IMU position and the first-level train GNSS position at t consecutive moments in the current positioning test period is calculated, where the position residual ΔP at the i-th moment is i The expression is as follows:

[0203]

[0204] S42. Optimize the GNSS position of first-level trains:

[0205] Calculate the probability Pr that the GNSS position of the i-th first-level train is a valid GNSS signal based on the position residual i , the expression is as follows:

[0206] Pr i =[(ΔP) max -ΔP i ] / |[(ΔP) max -(ΔP) min ]

[0207] Where (ΔP) max Indicates the maximum value in ΔP, (ΔP) min represents the minimum value in ΔP;

[0208] Initialize the probability threshold α and mark the GNSS position of the first-level train based on the relationship between the obtained probability and the probability threshold:

[0209] When Pr i≥α, the GNSS position of the i-th first-level train is marked as a valid GNSS signal. i <α, the GNSS position of the i-th first-level train is marked as an invalid GNSS signal;

[0210] S43. Reconstruct the secondary train GNSS position using all valid GNSS signals.

[0211] Furthermore, the step S5 includes:

[0212] Initialize the adjustment coefficients β and γ, where β + γ = 1;

[0213] The final position of the train is calculated by the train IMU position and the secondary train GNSS position, where the final position of the i-th train is The expression is as follows:

[0214]

[0215] in, represents the GNSS position of the i-th secondary train.

[0216] Furthermore, step S6 includes:

[0217] S61. Obtain the position P of the positioning tester C :

[0218]

[0219] Where w represents the number of secondary train GNSS positions;

[0220] S62. Trajectory consistency judgment:

[0221] During the positioning test period, the cumulative error e between the final position of the train and the position of the positioning tester is calculated, and the expression is as follows:

[0222]

[0223] Initialize the cumulative error threshold ε, and output the trajectory consistency judgment result based on the relationship between the obtained cumulative error and the cumulative error threshold:

[0224] When e≥ε, it means that the train positioning test track is consistent with the actual train track and the satellite positioning is accurate. When e<ε, it means that the train positioning test track is inconsistent with the actual train track and the satellite positioning is inaccurate.

[0225] Example 2

[0226] This embodiment provides a railway-specific satellite positioning test system for observation-restricted scenarios, including the following modules:

[0227] Offline data processing module: obtains the height values ​​of the train track and the surrounding environment of the train track, divides the train track into partitions, calculates the restriction of each track partition based on the height values ​​within the track partition, obtains the restricted track interval and uploads it to the positioning tester;

[0228] Real-time data acquisition module: obtains the train IMU position through the train IMU, obtains the first-level train GNSS position through the train GNSS receiver, and uploads the train IMU position and the first-level train GNSS position to the positioning tester;

[0229] Restricted scenario judgment module: Initializes the positioning test period and determines whether the train has passed through an observation-restricted scenario based on the train's current position and the restricted trajectory interval passed by the train during the positioning test period. If the train has not passed through an observation-restricted scenario, the trajectory consistency judgment module is run; otherwise, the GNSS signal optimization module is run.

[0230] GNSS signal screening module: Calculates the position residual between the train IMU position and the first-level train GNSS position during the positioning test period, and based on the position residual, selects the valid first-level train GNSS position and constructs the second-level train GNSS position.

[0231] Trajectory consistency judgment module: The final train position is calculated by the train IMU position and the first-level train GNSS position, or the final train position is calculated by the train IMU position and the second-level train GNSS position, and the position of the positioning tester is obtained. The trajectory consistency judgment is completed by the final train position and the positioning tester position within the positioning test time period.

[0232] This solution is applicable to both simulated and real scenarios.

[0233] The satellite positioning test system provided in this embodiment is used to implement the satellite positioning test method in the above-mentioned embodiment 1, wherein the functions implemented by each functional module of the satellite positioning test system correspond one-to-one to each step of the satellite positioning test method; therefore, they will not be repeated here.

[0234] It should be noted that the serial numbers of the above-mentioned embodiments of the present invention are for descriptive purposes only and do not represent the advantages or disadvantages of the embodiments. In addition, the terms "including", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "including a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0235] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0236] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A railway-specific satellite positioning test method for observation-restricted scenarios, characterized in that: The following steps are involved: S1. Obtain the height values ​​of the train track and the surrounding environment of the train track, divide the train track into sections, calculate the restriction of each track section based on the height values ​​within the track section, obtain the restricted track section and upload it to the positioning tester; S2. Obtain the train IMU position through the train IMU, obtain the first-level train GNSS position through the train GNSS receiver, and upload the train IMU position and the first-level train GNSS position to the positioning tester; S3. Initialize the positioning test period. Based on the train's current position and the restricted trajectory intervals passed by the train during the positioning test period, determine whether the train has passed through an observation-restricted scene. If the train has not passed through an observation-restricted scene, calculate the train's final position using the train's IMU position and the first-level train GNSS position, and execute step S6 to determine the trajectory consistency. Otherwise, execute step S4 to optimize the GNSS signal. S4. Calculate the position residual between the train IMU position and the primary train GNSS position during the positioning test period, select the valid primary train GNSS position based on the position residual, and construct the secondary train GNSS position based on it; S5. The final train position is calculated based on the train IMU position and the secondary train GNSS position; S6. Obtain the position of the positioning tester, and complete the trajectory consistency judgment based on the final position of the train and the position of the positioning tester during the positioning test period.

2. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 1 is characterized in that: The step S1 comprises: S11, obtaining the height value of the train running track and the environment around the train running track; S12, dividing the trajectory into zones: according to The train track is partitioned according to the specifications of a Greater than the train width, each track partition is the central axis of the train track it contains. The track part of the specification is calculated as a complete track partition to obtain the track partition : ； in: Indicates the first trajectory partition, Indicates the i Trajectory partitions, Indicates the n Trajectory partitions, n Indicates the number of trajectory partitions; S13, dividing the trajectory into sub-partitions: according to Each track partition is further divided into 9 track sub-partitions of the same size. The track sub-partitions are numbered 1-9 in the order of first along the width direction of the train and then along the length direction of the train. i The expression of the trajectory partition is as follows: ； in, Indicates the i The maximum height value of the first track sub-partition in the track partition, Indicates the i The first j The maximum height value of the trajectory sub-partition, Indicates the i The maximum height value of the 9th track sub-division within the track division; The 1st, 4th, and 7th track subpartitions are considered as the first side, the 2nd, 5th, and 8th track subpartitions are considered as the second side, and the 3rd, 6th, and 9th track subpartitions are considered as the third side; S14. Calculate the height of the trajectory sub-partition: Calculate trajectory partitions Average height of the first side , the average height of the second side and the average height of the third side , the expression is as follows: ； S15. Judgment of first and third side restrictions: Initialize height threshold ,Compare and The size of the value is based on the larger value and the height threshold The size relationship is used to determine the restricted conditions of the first and third sides. The expressions are as follows: ； in, Indicates the i The degree of limitation of the first and third sides within each trajectory partition; when When , it means that the GNSS observation is limited in the trajectory sub-area on the first side or the third side. When , it means that GNSS observations in the trajectory sub-area on the first or third side are not restricted; S16, second side restriction judgment: Initialize height difference threshold , calculate the difference in the mean height of the second side between adjacent trajectory partitions: ； Based on the obtained difference and the height difference threshold The relationship between the size of the second side is used to determine the limitation of the second side. The expression is as follows: ； in, Indicates the i The degree of limitation of the second side within each trajectory partition; when hour ， Indicates that the GNSS observations in the trajectory sub-area on the second side are limited. When , it means that GNSS observations in the trajectory sub-area on the second side are not restricted; S17, Constrained Integration Calculation: Calculate the i The limitation of trajectory partition , the expression is as follows: ； when When it is equal to 1 or 2, it means i GNSS observation is limited in each trajectory partition. There are observation-limited scenarios. When it is equal to 0, it means i GNSS observations are unrestricted within each trajectory partition, and there is no observation restriction scenario; S18, restricted trajectory interval: By calculating the restriction of each trajectory partition, the restricted trajectory interval is obtained : ； in, They represent the degree of restriction of different trajectory partitions respectively; S19, limit the trajectory interval Will be uploaded to the positioning tester.

3. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 1 is characterized in that: The step S2 comprises: S21. Get the train IMU position: The train IMU is located in the middle of the train, and the train IMU position is calculated by the train IMU signal : ； in, m Indicates the number of train IMU signals during the positioning test period. Indicates the i The train IMU position corresponding to each train IMU signal; S22. Obtain the GNSS position of the first-level train: Two GNSS receivers are located at the head and tail of the train respectively. The positions of the two GNSS receivers are obtained by receiving GNSS signals: ； in, Indicates the GNSS receiver at the head of the train. Indicates the GNSS receiver at the rear of the train, u Indicates the positioning test period The number of GNSS signals received by the receiver, express Receive the i The position when the GNSS signal is express Receive the i Position when receiving a GNSS signal; Depend on and Calculate the GNSS position of the first-level train : ； in, Indicates the i The train position corresponding to each GNSS signal; S23. Upload the train IMU position and the first-level train GNSS position to the positioning tester.

4. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 2, characterized in that: The step S3 comprises: S31. Determine the restricted track section that the train passes through: Initialize positioning test time period T , get the average speed of the train v , calculate the length of the test trajectory interval: ； in, represents the length coefficient; Calculate the number of trajectory partitions: ； Based on the current position of the train and the number of track partitions, determine the restricted track intervals that the train passes through during the positioning test period ; S32. Determine whether the train passes through an observation-restricted scene based on the restricted trajectory interval: When all the restricted values ​​within the restricted trajectory interval are zero, it means that during the positioning test period, the scenes passed by the train are all unrestricted observation scenes. The final position of the train is calculated by the first-level train GNSS position and the train IMU position, and step S6 is executed to determine the trajectory consistency. When a non-zero value exists in the restricted trajectory interval, it indicates that during the positioning test period, an observation restricted scene exists in the scene where the train passes, and step S4 is executed to optimize the GNSS signal.

5. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 3 is characterized in that: The step S4 comprises: S41. Calculate the position residual between the train IMU position and the first-level train GNSS position: At each moment, the train IMU collects a train IMU signal and the GNSS receiver receives a GNSS signal; Get the number of consecutive t The train IMU position at a certain moment: ； in, t is an integer and less than T ; Get the number of consecutive t GNSS position of the first-class train at a certain moment: ； Calculate the number of consecutive t The set of position residuals between the train IMU position and the first-level train GNSS position at time , among which, i Position residual at time The expression is as follows: ； S42. Optimize the GNSS position of first-level trains: Based on the position residuals, the i The probability that the GNSS position of a first-level train is a valid GNSS signal , the expression is as follows: ； in, express The maximum value in express The minimum value in ; Initialize probability threshold , based on the relationship between the obtained probability and the probability threshold, the GNSS position of the first-level train is marked: when When i The first-level train GNSS position is marked as a valid GNSS signal. When i The GNSS position of the first-level train is marked as invalid GNSS signal; S43. Reconstruct the secondary train GNSS position using all valid GNSS signals.

6. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 1, characterized in that: The step S5 comprises: Initialize adjustment coefficient and ,in, ; The final train position is calculated by the train IMU position and the secondary train GNSS position, where i Final train position The expression is as follows: ； in, Indicates the i Secondary train GNSS positions.

7. The railway-specific satellite positioning test method for observation-restricted scenarios according to claim 1, characterized in that: The step S6 comprises: S61. Obtain the location of the positioning tester : ； in, w Indicates the number of secondary train GNSS positions; S62. Trajectory consistency judgment: During the positioning test period, calculate the cumulative error between the final position of the train and the position of the positioning tester , the expression is as follows: ； Initialize the cumulative error threshold , based on the relationship between the obtained cumulative error and the cumulative error threshold, the trajectory consistency judgment result is output: when When the train positioning test track is consistent with the actual train track, the satellite positioning is accurate. When , it means that the train positioning test track is inconsistent with the actual train track and the satellite positioning is inaccurate.

8. A railway-specific satellite positioning test system for observation-restricted scenarios, used to implement the railway-specific satellite positioning test method according to any one of claims 1 to 7, characterized in that: Includes the following modules: Offline data processing module: obtains the height values ​​of the train track and the surrounding environment of the train track, divides the train track into partitions, calculates the restriction of each track partition based on the height values ​​within the track partition, obtains the restricted track interval and uploads it to the positioning tester; Real-time data acquisition module: obtains the train IMU position through the train IMU, obtains the first-level train GNSS position through the train GNSS receiver, and uploads the train IMU position and the first-level train GNSS position to the positioning tester; Restricted scenario judgment module: Initializes the positioning test period and determines whether the train has passed through an observation-restricted scenario based on the train's current position and the restricted trajectory interval passed by the train during the positioning test period. If the train has not passed through an observation-restricted scenario, the trajectory consistency judgment module is run; otherwise, the GNSS signal optimization module is run. GNSS signal optimization module: Calculates the position residual between the train IMU position and the first-level train GNSS position during the positioning test period, selects the valid first-level train GNSS position based on the position residual, and constructs the second-level train GNSS position based on it; Trajectory consistency judgment module: The final train position is calculated by the train IMU position and the first-level train GNSS position, or the final train position is calculated by the train IMU position and the second-level train GNSS position, and the position of the positioning tester is obtained. The trajectory consistency judgment is completed by the final train position and the positioning tester position within the positioning test time period.

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