A method for beacon sidelobe detection and improving train positioning accuracy

Abstract

The present invention discloses a method for detecting beacon side lobes and improving train positioning accuracy, comprising: step S1, obtaining the pulse count of a speed sensor through a beacon reader; step S2, the beacon reader uses radio frequency energy to read beacon data from a beacon installed on a track; step S3, the beacon reader sends beacon reading information to a VOBC; step S4, the VOBC calculates train positioning data according to the beacon information; step S5, the VOBC detects beacon side lobes according to the train positioning data; step S6, the VOBC updates the train position. The present invention improves the train positioning accuracy.

Description

Technical Field

[0001] The invention relates to a method for detecting beacon side lobes and improving train positioning accuracy. Background Art

[0002] In rail transit signal systems, beacons or transponders (hereinafter collectively referred to as beacons) are usually used to realize the positioning function of trains. Beacons are installed on the track, and the beacon identification and the position of the beacon on the track are defined in the on-board electronic map. The on-board controller (VOBC) of the signal system reads the beacon identification information of the track through the beacon reader installed on the train, obtains the position of the beacon on the track in the on-board electronic map through the beacon identification, and then determines the position of the train.

[0003] In order to meet the train positioning accuracy requirements, when VOBC receives the beacon identification information sent by the beacon reader, it needs to determine the distance range between the beacon reader antenna and the beacon when the beacon reader can read the valid beacon information (hereinafter collectively referred to as the contact length of the beacon, that is, the effective detection area length of the beacon), the deviation between the beacon reading position and the position of the beacon on the track (hereinafter collectively referred to as the beacon detection offset), and the distance traveled by the train from the beacon reader reading the beacon to the VOBC receiving the beacon information sent by the beacon reader (hereinafter collectively referred to as the beacon compensation distance). In the existing beacon-based train positioning technology, as shown in the attached Fig.11 As shown, VOBC obtains the beacon position from the on-board electronic map according to the identification of the received beacon, and then uses the beacon detection offset and beacon compensation distance to update the train position. The contact length of the beacon is usually a fixed value, and its value is based on the technical specifications of the beacon reader; the beacon detection offset Detection Offset and beacon compensation distance Compensation Distance are usually calculated using the following method:

[0004] Detection Offset=Contact Length×X,

[0005] Compensation Distance=v×T,

[0006] Among them, X is a fixed parameter, and its value is a decimal between -1 and 1. v is the speed of the train when VOBC receives the beacon identification information sent by the beacon reader. T is a fixed parameter, which is composed of the beacon reader processing time, beacon information transmission delay, VOBC processing time and other durations. These durations are parameter values ​​pre-defined by the system.

[0007] When the VOBC receives the beacon identification information sent by the beacon reader, the train position is updated as follows:

[0008] Train Position=Tag Position-Detection Offset+Compensation Distance,

[0009] In the above-mentioned method for updating the train position, the contact length of the beacon adopts a fixed value, which is related to the installation standards such as the installation height of the beacon reader. Since installation errors are inevitable, there is a deviation between the predefined contact length of the beacon and the contact length during the actual beacon detection; secondly, in the calculation of the beacon compensation distance, the train speed value adopts the speed when VOBC receives the beacon information sent by the beacon reader. If the train speed changes within the time T, for example, the train is in the process of acceleration or deceleration, the speed v value involved in the calculation will deviate from the actual train speed. In addition, there will also be a deviation between the fixed parameter T and the actual beacon processing delay.

[0010] In addition, due to beacon reader installation errors and track environment interference, there are inevitably sidelobe areas for beacon detection. The beacon may be detected in the sidelobe area, causing the beacon to be detected early or late.

[0011] The existence of the above-mentioned train position update calculation deviation and the detection of the beacon in the sidelobe area result in poor positioning accuracy of the positioning method using the beacon, which has a great impact on the automatic train operation (ATO) control, especially the train entry beaconing, and affects the train platform beaconing accuracy.

[0012] Therefore, a method for beacon sidelobe detection and improving train positioning accuracy is provided. Summary of the invention

[0013] The purpose of the present invention is to overcome the existing defects and provide a method for beacon sidelobe detection and improving train positioning accuracy, thereby improving the train positioning accuracy.

[0014] The technical solution to achieve the above purpose is:

[0015] A method for beacon sidelobe detection and improving train positioning accuracy, comprising:

[0016] Step S1, obtaining the pulse count of the speed sensor through the beacon reader;

[0017] Step S2, the beacon reader uses radio frequency energy to read beacon data from the beacons installed on the track;

[0018] Step S3, the beacon reader sends beacon reading information to VOBC;

[0019] Step S4, VOBC calculates train positioning data according to beacon information;

[0020] Step S5, VOBC detects beacon side lobes according to train positioning data;

[0021] Step S6, VOBC updates the train position.

[0022] Preferably, the step S1 comprises:

[0023] Step S11, adding a communication interface from VOBC to beacon reader between VOBC and beacon reader;

[0024] Step S12, VOBC calculates pulse count according to wheel speed pulse output by speed sensor;

[0025] Step S13, VOBC sends the pulse count to the beacon reader at a predetermined period.

[0026] Preferably, in step S13, the period at which VOBC sends pulse counts to the beacon reader is consistent with the beacon reading processing period of the beacon reader. At the beginning of each beacon reading processing period, the beacon reader receives the pulse count value sent by VOBC and saves it as the current pulse count of the train, recorded as Train_Current_Pulse_Count.

[0027] Preferably, the step S2 comprises:

[0028] Step S21, the beacon reader first determines whether the radio frequency signal strength exceeds the beacon reading signal strength threshold for the first time in each beacon reading cycle;

[0029] Step S22, if it is determined that the RF signal strength exceeds the beacon reading signal strength threshold for the first time, the beacon reader sets the beacon reading flag and saves the current pulse count of the train as the beacon reading start pulse count, recorded as Pulse_Count_Read_Start, that is, Pulse_Count_Read_Start = Train_Current_Pulse_Count;

[0030] Step S23, the beacon reader will start to receive and decode the uplink signal. If the beacon data can be correctly obtained, the current pulse count of the train will be saved as the beacon read pulse count, recorded as Pulse_Count_Read_Tag, that is, Pulse_Count_Read_Tag = Train_Current_Pulse_Count;

[0031] Step S24, saving the beacon reading pulse count and beacon data combination into a beacon reading result list;

[0032] Step S25, if it is determined that the RF signal strength does not exceed the beacon reading signal strength threshold for the first time, then determine whether the RF signal strength exceeds the beacon reading signal strength threshold;

[0033] Step S26, if the RF signal strength exceeds the beacon reading signal strength threshold, the beacon reader continues to receive and decode the uplink signal;

[0034] Step S27: If the beacon data can be correctly obtained and the beacon data is different from the beacon data in the beacon reading result list, the current pulse count of the train is saved as the beacon reading pulse count, that is, Pulse_Count_Read_Tag, Pulse_Count_Read_Tag = Train_Current_Pulse_Count;

[0035] Step S28, if the RF signal strength is less than the beacon reading signal strength threshold and the beacon reading flag is valid, clear the beacon reading flag, save the train current pulse count as the beacon reading end pulse count, recorded as Pulse_Count_Read_End, that is, Pulse_Count_Read_End = Train_Current_Pulse_Count;

[0036] Step S29, then determine whether the beacon data is read. If the beacon data is read, that is, the beacon reading result list is not empty, then save the beacon reading start pulse count Pulse_Count_Read_Start, the beacon reading end pulse count Pulse_Count_Read_End and the data in the beacon reading result list to the beacon information sending queue, and clear the data in the beacon reading result list.

[0037] Preferably, in step S29, the structure of each element of the beacon message sending queue is:

[0038] {Pulse_Count_Read_Start,Pulse_Count_Read_End,

[0039] {{Pulse_Count_Read_Tag_1, beacon data

[0040] _1},{Pulse_Count_Read_Tag_2, beacon data

[0041] _2}, …, {{Pulse_Count_Read_Tag_N, Beacon_Data_N}}}.

[0042] Preferably, in step S3, the beacon reader sends a communication message to the VOBC according to a predetermined communication cycle. If the beacon message sending queue is not empty, the beacon reader sequentially takes out beacon information from the beacon message sending queue and sends it to the VOBC;

[0043] The beacon reader sends the following data to VOBC in sequence according to the communication cycle:

[0044] {Pulse_Count_Read_Start, Pulse_Count_Read_End, Pulse_Count_Read_Tag_i,

[0045] beacon_data_i}, i=1,2,…,N;

[0046] Each beacon information sent to VOBC includes a beacon read start pulse count, a beacon read end pulse count, a beacon read pulse count and beacon data.

[0047] Preferably, in step S4, after the VOBC receives the beacon information sent by the beacon reader, it performs the following processing according to the pulse count of the speedometer:

[0048] Calculate the beacon contact length Contact_Length read by the beacon according to the following formula:

[0049]

[0050] Calculate the beacon compensation distance Compensation_Distance according to the following formula:

[0051]

[0052] Where, π is the circumference of a circle, D is the wheel diameter of the train, Pulse_Count_Read_Start is the beacon reading start pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_End is the beacon reading end pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_Tag is the beacon reading pulse count sent by the beacon reader to VOBC, Pulse_Count_Current is the pulse count calculated based on the wheel speed pulse output by the speed sensor when VOBC receives the beacon information sent by the beacon reader, N_Pulse_Count_Per_Wheel_Revolution is the number of pulses corresponding to one rotation of the train wheel, which is a fixed parameter of the system and is related to the technical specifications of the speed sensor;

[0053] In step S5, VOBC determines whether the beacon is within the length range of the main lobe region according to the beacon contact length when the beacon is read, and can determine whether the beacon is read in the side lobe region or in the main lobe region, that is:

[0054] Determine the length range of the main lobe area read by the beacon based on the relevant technical specifications of the beacon reader and actual physical measurements combined with actual test data analysis;

[0055] The minimum beacon contact length MIN_CONTACT_LENGTH and the maximum beacon contact length MAX_CONTACT_LENGTH of the main lobe area, the length range of the main lobe area of ​​the beacon is:

[0056] [MIN_CONTACT_LENGTH, MAX_CONTACT_LENGTH];

[0057] If satisfied:

[0058] MIN_CONTACT_LENGTH≤Contact_Length≤MAX_CONTACT_LENGTH;

[0059] Then it is determined that the beacon is read in the main lobe area, otherwise it is determined that there are side lobes in the beacon reading process, that is, the beacon may be read in the side lobe area;

[0060] When VOBC determines that the beacon is read in the side lobe area, VOBC sends an alarm message to ATS, indicating that the beacon side lobe is detected. The operation and maintenance personnel determine whether the beacon reader equipment needs to be maintained based on the alarm prompt frequency.

[0061] Wherein, Contact_Length is the beacon contact length measured when the beacon is read.

[0062] Preferably, step S6 comprises:

[0063] Step S61, VOBC obtains beacon identification information according to beacon data sent by the beacon reader, and VOBC determines whether the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon;

[0064] Step S62, if it is determined that the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon, the train position is no longer updated using the beacon information;

[0065] Step S63: If it is determined that the train position has not been updated using the beacon information detected in the main lobe area of ​​the beacon, the beacon position Tag_Position is obtained from the on-board electronic map according to the beacon identifier, and then the beacon detection offset Detection_Offset is determined.

[0066] Preferably, in step S63, if the beacon is read in the main lobe region, the calculation method of Detection_Offset is as follows:

[0067] Detection_Offset = Contact_Length × X;

[0068] In the formula, X is a fixed parameter, and its value is a decimal between -1 and 1. The value is determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with actual test data analysis;

[0069] If the beacon is read in the side lobe region and the train has not established positioning, it means that the beacon is read in the side lobe region during the train positioning establishment process. It is processed in the following two cases:

[0070] If Contact_Length < MIN_CONTACT_LENGTH, it means that the beacon is read in the side lobe region. When it is impossible to determine whether the train has passed the beacon when the VOBC receives the beacon information, the beacon information read in the side lobe region during the train positioning establishment process is not used to update the train position, and this processing ends;

[0071] If Contact_Length > MAX_CONTACT_LENGTH, it means that the side lobe region and the main lobe region of the beacon are connected together, indicating that the train has passed the beacon when the VOBC receives the beacon information. During the train positioning establishment process, Distance_Offset = 0.

[0072] Preferably, in step S63, if the beacon is read in the side lobe region and the train has already established positioning, the calculation method of Distance_Offset is as follows:

[0073] The VOBC calculates the train position when the beacon reader reads the beacon according to the train position when receiving the beacon information sent by the beacon reader. The calculation method is as follows:

[0074] The position obtained by moving the beacon compensation distance in the reverse direction of the train operation from the train position when receiving the beacon information sent by the beacon reader;

[0075] Calculate the distance Distance_Offset from the train position when the beacon reader reads the beacon to the beacon position obtained from the on-vehicle electronic map;

[0076] In the running direction of the train, if the train position when the beacon is read by the beacon reader is behind the beacon position obtained from the on-vehicle electronic map, then Detection_Offset = Distance_Offset; otherwise, Detection_Offset = -Distance_Offset;

[0077] Finally, the VOBC updates the train position based on the beacon position Tag_Position, the beacon detection offset Detection_Offset, and the beacon compensation distance Compensation_Distance, that is, the train position is updated to:

[0078] Train_Position = Tag_Position - Detection_Offset + Compensation_Distance;

[0079] When the VOBC determines that the beacon is read in the sidelobe area, after updating the train positioning, the position uncertainty of the train needs to increase the train positioning error value, and the specific processing is as follows:

[0080] If Contact_Length < MIN_CONTACT_LENGTH, the position uncertainty of the train needs to increase by SIDE_LOBE_ERROR_MIN_CL;

[0081] If Contact_Length > MAX_CONTACT_LENGTH, the position uncertainty of the train needs to increase by SIDE_LOBE_ERROR_MAX_CL;

[0082] Among them, SIDE_LOBE_ERROR_MIN_CL and SIDE_LOBE_ERROR_MAX_CL are determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with actual test data analysis.

[0083] The beneficial effects of the present invention are:

[0084] 1) The present invention optimizes the processing flow of the beacon reader for reading beacons. By sending the data of the speed sensor to the beacon reader through the VOBC, the beacon reader can associate the train movement distance with each process of beacon reading, and the system can provide a more accurate method to measure the beacon reading area;

[0085] 2) Using the data measured by the speed sensor to calculate the beacon detection length and the beacon compensation distance to update the train positioning, rather than using predefined parameters for calculation, makes the positioning parameter calculation more in line with the actual beacon reading situation and improves the train positioning accuracy;

[0086] 3) The beacon sidelobe detection method enables the system to process beacons read in the main lobe area and the side lobe area differently, thereby improving the train positioning accuracy. At the same time, by reporting beacon sidelobe alarms, it can provide reminders for the maintenance of the beacon reader to avoid equipment failures affecting operations;

[0087] 4) The implementation of the method provided by the present invention does not require any hardware modification, and only requires the vehicle controller and beacon reader software to be upgraded. The method can be implemented on the original system at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 It is a flow chart of a method for beacon sidelobe detection and improving train positioning accuracy of the present invention;

[0089] Figure 2 is a specific flow chart of obtaining the pulse count of the speed sensor through the beacon reader in the present invention;

[0090] Figure 3 is a specific flow chart of the beacon reader of the present invention using radio frequency energy to read beacon data from beacons installed on the track;

[0091] Figure 4 It is a specific flow chart of VOBC updating train position in the present invention;

[0092] Figure 5 It is a schematic diagram of the system architecture of the present invention;

[0093] Figure 6 is a schematic diagram of a beacon main lobe area in an embodiment of the present invention, where the beacon will only be read in the main lobe area;

[0094] Figure 7 It is a schematic diagram showing that in an embodiment of the present invention, there is a beacon side lobe area, but the beacon main lobe and side lobe areas are separated, and the beacon can be read in the main lobe or side lobe area;

[0095] Figure 8 It is a schematic diagram showing that in an embodiment of the present invention, there is a beacon side lobe area, and the beacon main lobe and side lobe areas are connected together, and the beacon will be read in the main lobe or side lobe area;

[0096] Fig. 9 is a schematic diagram of an embodiment of the present invention in which a beacon is read in a sidelobe region and a train has established positioning;

[0097] Fig.10 is a schematic diagram of vehicle positioning update in an embodiment of the present invention;

[0098] Fig.11 It is a schematic diagram of train positioning update in the traditional technical solution. DETAILED DESCRIPTION

[0099] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0100] The present invention will be further described below in conjunction with the accompanying drawings.

[0101] like Figure 1 As shown, a method for beacon sidelobe detection and improving train positioning accuracy includes:

[0102] Step S1, obtaining the pulse count of the speed sensor through the beacon reader.

[0103] like Figure 2 As shown, step S1 includes:

[0104] Step S11, adding a communication interface from VOBC to the beacon reader between VOBC and the beacon reader.

[0105] Step S12, VOBC calculates the pulse count based on the wheel speed pulse output by the speed sensor.

[0106] Step S13, VOBC sends the pulse count to the beacon reader at a predetermined period.

[0107] In the embodiment, the period in which VOBC sends pulse counts to the beacon reader is consistent with the beacon reading processing period of the beacon reader. At the beginning of each beacon reading processing period, the beacon reader receives the pulse count value sent by VOBC and saves it as the current pulse count of the train, recorded as Train_Current_Pulse_Count.

[0108] In step S2, a beacon reader uses radio frequency energy to read beacon data from beacons installed on the track.

[0109] like Figure 3 As shown, step S2 includes:

[0110] In step S21, the beacon reader first determines whether the radio frequency signal strength exceeds the beacon reading signal strength threshold for the first time in each beacon reading cycle.

[0111] Step S22, if it is determined that the RF signal strength exceeds the beacon reading signal strength threshold for the first time, the beacon reader sets the beacon reading flag and saves the current pulse count of the train as the beacon reading start pulse count, recorded as Pulse_Count_Read_Start, that is, Pulse_Count_Read_Start = Train_Current_Pulse_Count.

[0112] In step S23, the beacon reader will start to receive and decode the uplink signal. If the beacon data can be correctly obtained, the current pulse count of the train will be saved as the beacon read pulse count, recorded as Pulse_Count_Read_Tag, that is, Pulse_Count_Read_Tag = Train_Current_Pulse_Count.

[0113] Step S24, saving the beacon reading pulse count and beacon data combination into the beacon reading result list.

[0114] Step S25: If it is determined that the RF signal strength does not exceed the beacon reading signal strength threshold for the first time, it is determined whether the RF signal strength exceeds the beacon reading signal strength threshold.

[0115] Step S26: If the RF signal strength exceeds the beacon reading signal strength threshold, the beacon reader continues to receive and decode the uplink signal.

[0116] Step S27, if the beacon data can be correctly obtained and the beacon data is different from the beacon data in the beacon reading result list, the current pulse count of the train is saved as the beacon read pulse count, that is, Pulse_Count_Read_Tag, Pulse_Count_Read_Tag = Train_Current_Pulse_Count.

[0117] Step S28, if the RF signal strength is less than the beacon read signal strength threshold and the beacon read flag is valid, clear the beacon read flag, save the train current pulse count as the beacon read end pulse count, recorded as Pulse_Count_Read_End, that is, Pulse_Count_Read_End = Train_Current_Pulse_Count.

[0118] Step S29, then determine whether the beacon data is read. If the beacon data is read, that is, the beacon reading result list is not empty, then save the beacon reading start pulse count Pulse_Count_Read_Start, the beacon reading end pulse count Pulse_Count_Read_End and the data in the beacon reading result list to the beacon information sending queue, and clear the data in the beacon reading result list.

[0119] In the embodiment, the structure of each element of the beacon message sending queue is:

[0120] {Pulse_Count_Read_Start,Pulse_Count_Read_End,

[0121] {{Pulse_Count_Read_Tag_1, beacon data

[0122] _1},{Pulse_Count_Read_Tag_2, beacon data

[0123] _2}, …, {{Pulse_Count_Read_Tag_N, Beacon_Data_N}}}.

[0124] That is, each element in the beacon message sending queue stores all the different beacon data read in a complete beacon reading process. During the beacon reading process, unless signal crosstalk occurs, that is, the beacon reader reads a beacon that is not at the current position of the train, such as a beacon on an adjacent track, there is only one set of data in the beacon reading result list, that is, the element structure of the beacon sending queue is:

[0125] {Pulse_Count_Read_Start, Pulse_Count_Read_End, {Pulse_Count_Read_Tag, beacon data}}, that is, the above structure N=1.

[0126] Step S3, the beacon reader sends beacon reading information to VOBC.

[0127] In the embodiment, the beacon reader sends a communication message to the VOBC according to a predetermined communication cycle. If the beacon message sending queue is not empty, the beacon reader sequentially takes out the beacon information from the beacon message sending queue and sends it to the VOBC;

[0128] The beacon reader sends the following data to VOBC in sequence according to the communication cycle:

[0129] {Pulse_Count_Read_Start, Pulse_Count_Read_End, Pulse_Count_Read_Tag_i,

[0130] beacon_data_i}, i=1,2,…,N;

[0131] Each beacon information sent to VOBC includes the beacon read start pulse count, beacon read end pulse count, beacon read pulse count and beacon data; the beacon reader obtains the beacon information from the beacon message sending queue and sends it to VOBC, ensuring that the beacon reader sends the read beacon information to VOBC only after the entire beacon reading process is completed.

[0132] Step S4, VOBC calculates train positioning data based on beacon information.

[0133] In the embodiment, when the VOBC receives the beacon information sent by the beacon reader, it performs the following processing according to the pulse count of the speedometer:

[0134] Calculate the beacon contact length Contact_Length read by the beacon according to the following formula:

[0135]

[0136] Calculate the beacon compensation distance Compensation_Distance according to the following formula:

[0137]

[0138] Wherein, π is the pi, D is the wheel diameter of the train, Pulse_Count_Read_Start is the beacon read start pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_End is the beacon read end pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_Tag is the beacon read pulse count sent by the beacon reader to VOBC, Pulse_Count_Current is the pulse count calculated according to the wheel speed pulse output by the speed sensor when VOBC receives the beacon information sent by the beacon reader, and N_Pulse_Count_Per_Wheel_Revolution is the number of pulses corresponding to one rotation of the train wheel. It is a fixed parameter of the system and is related to the technical specifications of the speed sensor.

[0139] Step S5, VOBC detects beacon side lobes according to train positioning data.

[0140] In the embodiment, VOBC determines whether the beacon is within the length range of the main lobe region according to the beacon contact length when the beacon is read, and can determine whether the beacon is read in the side lobe region or in the main lobe region, that is:

[0141] Determine the length range of the main lobe area read by the beacon based on the relevant technical specifications of the beacon reader and actual physical measurements combined with actual test data analysis;

[0142] The minimum beacon contact length MIN_CONTACT_LENGTH and the maximum beacon contact length MAX_CONTACT_LENGTH of the main lobe area, the length range of the main lobe area of ​​the beacon is:

[0143] [MIN_CONTACT_LENGTH, MAX_CONTACT_LENGTH];

[0144] If satisfied:

[0145] MIN_CONTACT_LENGTH≤Contact_Length≤MAX_CONTACT_LENGTH;

[0146] Then it is determined that the beacon is read in the main lobe area, otherwise it is determined that there are side lobes in the beacon reading process, that is, the beacon may be read in the side lobe area;

[0147] When VOBC determines that the beacon is read in the side lobe area, VOBC sends an alarm message to ATS, indicating that the beacon side lobe is detected. The operation and maintenance personnel determine whether the beacon reader equipment needs to be maintained based on the alarm prompt frequency.

[0148] Wherein, Contact_Length is the beacon contact length measured when the beacon is read.

[0149] Step S6, VOBC updates the train position.

[0150] like Figure 4 As shown, step S6 includes:

[0151] Step S61, VOBC obtains beacon identification information based on the beacon data sent by the beacon reader, and VOBC determines whether the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon.

[0152] Step S62: If it is determined that the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon, the train position is no longer updated using the beacon information.

[0153] Step S63: If it is determined that the train position has not been updated using the beacon information detected in the main lobe area of the beacon, obtain the beacon position Tag_Position from the on-vehicle electronic map according to the beacon identifier, and then determine the beacon detection offset Detection_Offset according to the following steps.

[0154] In the embodiment, if the beacon is read in the main lobe area, the calculation method of Detection_Offset is:

[0155] Detection_Offset = Contact_Length × X;

[0156] In the formula, X is a fixed parameter, and its value is a decimal between -1 and 1. The value is determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with actual test data analysis;

[0157] If the beacon is read in the side lobe area and the train has not established positioning, it means that the beacon is read in the side lobe area during the train positioning establishment process. It is processed in the following two cases:

[0158] If Contact_Length < MIN_CONTACT_LENGTH, it means that the beacon is read in the side lobe area, and it is impossible to determine whether the train has passed the beacon when the VOBC receives the beacon information. Therefore, during the train positioning establishment process, the beacon information read in the side lobe area is not used to update the train position, and this processing ends;

[0159] If Contact_Length > MAX_CONTACT_LENGTH, it means that the side lobe area and the main lobe area of the beacon are connected together, indicating that the train has passed the beacon when the VOBC receives the beacon information. During the train positioning establishment process, Distance_Offset = 0.

[0160] In the embodiment, if the beacon is read in the side lobe area and the train has already established positioning, the calculation method of Distance_Offset is as follows:

[0161] The VOBC calculates the train position when the beacon reader reads the beacon according to the train position when receiving the beacon information sent by the beacon reader. The calculation method is:

[0162] The position obtained by moving the beacon compensation distance in the reverse direction of the train operation from the train position when receiving the beacon information sent by the beacon reader;

[0163] Calculate the distance Distance_Offset from the train position when the beacon reader reads the beacon to the beacon position obtained from the on-vehicle electronic map;

[0164] In the running direction of the train, if the train position when the beacon is read by the beacon reader is behind the beacon position obtained from the on-vehicle electronic map, then Detection_Offset = Distance_Offset; otherwise, Detection_Offset = -Distance_Offset;

[0165] Finally, the VOBC updates the train position based on the beacon position Tag_Position, the beacon detection offset Detection_Offset, and the beacon compensation distance Compensation_Distance, that is, the train position is updated to:

[0166] Train_Position = Tag_Position - Detection_Offset + Compensation_Distance;

[0167] When the VOBC determines that the beacon is read in the sidelobe region, after updating the train positioning, the position uncertainty of the train needs to increase the train positioning error value, and the specific processing is as follows:

[0168] If Contact_Length < MIN_CONTACT_LENGTH, the position uncertainty of the train needs to increase by SIDE_LOBE_ERROR_MIN_CL;

[0169] If Contact_Length > MAX_CONTACT_LENGTH, the position uncertainty of the train needs to increase by SIDE_LOBE_ERROR_MAX_CL;

[0170] Among them, SIDE_LOBE_ERROR_MIN_CL and SIDE_LOBE_ERROR_MAX_CL are determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with actual test data analysis.

[0171] This embodiment uses the European beacon positioning method. The beacon reader uses a BTM transponder device, which consists of two parts: a BTM host and a BTM antenna. The system architecture is as shown in the appendix Figure 5 As shown, the BTM host obtains speed sensor data from the VOBC.

[0172] The following is an implementation case executed according to the steps shown in the appendix Figure 1 This invention relates to an on-vehicle controller (VOBC) and a BTM host device (for the sake of unifying the description of the invention content, hereinafter still collectively referred to as the beacon reader). The following will be based on the appendix Figure 1The specific implementation process of the above-mentioned inventive method is described in detail, and the specific steps are as follows:

[0173] Step 1:

[0174] According to the relevant technical specifications of the beacon reader (BTM transponder) and the actual physical measurements combined with the actual test data analysis, the train positioning related parameters are defined in the VOBC software. The parameters involved are:

[0175] MIN_CONTACT_LENGTH: minimum beacon contact length in the main lobe area, which is 400 mm in this embodiment;

[0176] MAX_CONTACT_LENGTH: the maximum beacon contact length in the main lobe area, which is 800 mm in this embodiment;

[0177] X: beacon detection offset coefficient in the main lobe area, based on the technical feature of symmetric contact length of the European beacon, the value is 0 in this embodiment;

[0178] SIDE_LOBE_ERROR_MIN_CL: when the beacon is read when the beacon contact length is less than MIN_CONTACT_LENGTH, the value by which the train position uncertainty needs to be increased. In this embodiment, the value is 900mm;

[0179] SIDE_LOBE_ERROR_MAX_CL: when the beacon is read when the beacon contact length is greater than MAX_CONTACT_LENGTH, the train position uncertainty needs to be increased by a value, which is 500mm in this embodiment;

[0180] N_Pulse_Count_Per_Wheel_Revolution: the pulse count generated by the speed sensor when the train wheel rotates one circle. The speed sensor used in this embodiment takes a value of 100.

[0181] Step 2:

[0182] The speed sensor used in this embodiment is installed on the brake shaft of the train. There is a gear inside the speed sensor. The speed sensor will be able to sense the teeth of the speed sensor gear. The speed sensor channel generates two output streams with a phase angle difference of 90 degrees. The two output streams provide 100 speed pulses per revolution, and the frequency of the pulses is proportional to the angular velocity of the train wheels. VOBC calculates the pulse count based on the wheel speed pulses output by the speed sensor. The pulse count of the speed sensor divided by 100 can determine the number of rotations of the wheel, and combined with the diameter of the train wheel, the travel distance of the train can be calculated.

[0183] VOBC obtains the speed pulses generated by the speed sensor according to a predetermined sampling period, determines the pulse count of each sampling period based on the speed pulses, and obtains the pulse count since the system was started by accumulating the pulse count of each sampling period.

[0184] A communication interface from VOBC to beacon reader is added between VOBC and beacon reader, and VOBC sends pulse counts to beacon reader at a predetermined period. The period of VOBC sending pulse counts to beacon reader is consistent with the beacon reading processing period of beacon reader, ensuring that beacon reader can obtain the pulse count of current train movement before beacon reading processing. At the beginning of each beacon reading processing period, beacon reader receives the pulse count value sent by VOBC and saves it as the current pulse count of the train, recorded as Train_Current_Pu l se_Count, ensuring that the beacon reader has obtained the latest pulse count calculated by VOBC before the beacon reading process starts.

[0185] Step 3:

[0186] In each beacon reading cycle, the beacon reader first determines whether the RF signal strength exceeds the beacon reading signal strength threshold for the first time (i.e., whether the RF signal strength changes from less than the beacon reading signal strength threshold to greater than the beacon reading signal strength threshold);

[0187] If it is determined that the RF signal strength exceeds the beacon reading signal strength threshold for the first time, the beacon reader sets the beacon reading flag and saves the train current pulse count as the beacon reading start pulse count, recorded as Pulse_Count_Read_Start, that is, Pulse_Count_Read_Start = Train_Current_Pulse_Count;

[0188] The beacon reader will start to receive and decode the uplink signal. If the beacon data can be obtained correctly, the current pulse count of the train will be saved as the beacon read pulse count, recorded as Pulse_Count_Read_Tag, that is, Pulse_Count_Read_Tag = Train_Current_Pulse_Count; then the beacon read pulse count and beacon data combination will be saved in the beacon read result list.

[0189] If it is determined that the radio frequency signal strength does not exceed the beacon reading signal strength threshold for the first time, then determine whether the radio frequency signal strength exceeds the beacon reading signal strength threshold;

[0190] If the RF signal strength exceeds the beacon reading signal strength threshold, the beacon reader continues to receive and decode the uplink signal;

[0191] If the beacon data can be obtained correctly, and the beacon data is different from the beacon data in the beacon reading result list, the current pulse count of the train is saved as the beacon reading pulse count, that is, Pulse_Count_Read_Tag, Pulse_Count_Read_Tag = Train_Current_Pulse_Count;

[0192] The beacon read pulse count and beacon data combination is then added and saved to the beacon read result list.

[0193] If the RF signal strength is less than the beacon reading signal strength threshold and the beacon reading flag is valid, the beacon reading flag is cleared, and the train current pulse count is saved as the beacon reading end pulse count, recorded as Pulse_Count_Read_End, that is, Pulse_Count_Read_End = Train_Current_Pulse_Count;

[0194] Then determine whether the beacon data is read. If the beacon data is read, that is, the beacon reading result list is not empty, save the beacon reading start pulse count Pulse_Count_Read_Start, the beacon reading end pulse count Pulse_Count_Read_End and the data in the beacon reading result list to the beacon information sending queue, and clear the data in the beacon reading result list.

[0195] The structure of each element of the beacon message sending queue is:

[0196] {Pulse_Count_Read_Start,Pulse_Count_Read_End,

[0197] {{Pulse_Count_Read_Tag_1, beacon data

[0198] _1},{Pulse_Count_Read_Tag_2, beacon data

[0199] _2}, …, {{Pulse_Count_Read_Tag_N, Beacon_Data_N}}}.

[0200] That is, each element in the beacon message sending queue stores all the different beacon data read in a complete beacon reading process. During the beacon reading process, unless signal crosstalk occurs, that is, the beacon reader reads a beacon that is not at the current position of the train, such as a beacon on an adjacent track, there is only one set of data in the beacon reading result list, that is, the element structure of the beacon sending queue is:

[0201] {Pulse_Count_Read_Start, Pulse_Count_Read_End, {Pulse_Count_Read_Tag, beacon data}}, that is, the above structure N=1.

[0202] Step 4:

[0203] The beacon reader sends a communication message to the VOBC according to the predetermined communication cycle. If the beacon message sending queue is not empty, the beacon reader sequentially takes out the beacon information from the beacon message sending queue and sends it to the VOBC. According to step 3, the structure of each beacon information in the beacon message sending queue is:

[0204] {Pulse_Count_Read_Start,Pulse_Count_Read_End,

[0205] {{Pulse_Count_Read_Tag_1, beacon data

[0206] _1},{Pulse_Count_Read_Tag_2, beacon data

[0207] _2}, …, {{Pulse_Count_Read_Tag_N, Beacon_Data_N}}},

[0208] The beacon reader sends the following data to VOBC in sequence according to the communication cycle:

[0209] {Pulse_Count_Read_Start, Pulse_Count_Read_End, Pulse_Count_Read_Tag_i,

[0210] Beacon data_i}, i=1,2,…,N.

[0211] That is, each beacon information sent to VOBC includes a beacon read start pulse count, a beacon read end pulse count, a beacon read pulse count and beacon data.

[0212] The beacon reader obtains the beacon information from the beacon message sending queue and sends it to the VOBC, ensuring that the beacon reader sends the read beacon information to the VOBC only after the entire beacon reading process is completed.

[0213] Step 5:

[0214] When VOBC receives the beacon information sent by the beacon reader, it performs the following processing according to the pulse count of the speedometer:

[0215] Calculate the beacon contact length Contact_Length read by the beacon according to the following formula:

[0216]

[0217] Calculate the beacon compensation distance Compensation_Distance according to the following formula:

[0218]

[0219] In the above formula, π is the pi, D is the wheel diameter of the train, which is the VOBC software system parameter. The wheel diameter will be accurately calculated through the wheel diameter correction function; Pulse_Count_Read_Start is the beacon read start pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_End is the beacon read end pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_Tag is the beacon read pulse count sent by the beacon reader to VOBC, and Pulse_Count_Current is the pulse count calculated by VOBC based on the wheel speed pulse output by the speed sensor when VOBC receives the beacon information sent by the beacon reader.

[0220] In practical applications, the calculation of the above formula needs to take into account the overflow flipping of unsigned integer data.

[0221] Step 6:

[0222] VOBC determines whether the beacon is within the length range of the main lobe area based on the beacon contact length when the beacon is read, and can determine whether the beacon is read in the side lobe area or the main lobe area.

[0223] If the following conditions are met:

[0224] MIN_CONTACT_LENGTH≤Contact_Length≤MAX_CONTACT_LENGTH,

[0225] Wherein Contact_Length is the beacon contact length measured when the beacon is read, and the beacon is judged to be read in the main lobe area, otherwise it is judged that there is a side lobe during the beacon reading process, that is, the beacon may be read in the side lobe area.

[0226] Attached Figure 6-8 It shows three situations of the main lobe and side lobe areas of the beacon. Figure 6 This is the main lobe area of ​​the beacon. The beacon will only be read in the main lobe area. Figure 7 There is a beacon sidelobe area, but the beacon main lobe and sidelobe areas are separate, and the beacon will be read in the main lobe or sidelobe area; Figure 8 There is a beacon sidelobe area, and the main lobe and sidelobe areas of the beacon are connected. The beacon will be read in the main lobe or sidelobe area.

[0227] When the VOBC determines that the beacon is read in the sidelobe area, the VOBC sends an alarm message to the ATS, indicating that the beacon sidelobe is detected. The maintenance personnel can determine whether maintenance of the beacon reader device is required based on the alarm prompt frequency.

[0228] Step Seven:

[0229] The VOBC obtains the beacon identification information based on the beacon data sent by the beacon reader. The VOBC determines whether the train position has been updated using the beacon information detected in the main lobe area of the beacon. If it is determined that the train position has been updated using the beacon information detected in the main lobe area of the beacon, the information of this beacon will no longer be used to update the train position. If it is determined that the train position has not been updated using the beacon information detected in the main lobe area of the beacon, the beacon position Tag_Position is obtained from the on-vehicle electronic map according to the beacon identification, and then the beacon detection offset Detection_Offset is determined according to the following steps.

[0230] If the beacon is read in the main lobe area, the calculation method of Detection_Offset is:

[0231] Detection_Offset = Contact_Length × X,

[0232] If the beacon is read in the sidelobe area and the train has not established positioning, it means that the beacon is read in the sidelobe area during the train positioning establishment process. It is processed in the following two cases:

[0233] If Contact_Length < MIN_CONTACT_LENGTH, it means that the beacon is read in the sidelobe area, and it is impossible to determine whether the train has passed the beacon when the VOBC receives the beacon information. Therefore, during the train positioning establishment process, the beacon information read in the sidelobe area is not used to update the train position, and this processing ends.

[0234] If Contact_Length > MAX_CONTACT_LENGTH, it means that the sidelobe area and the main lobe area of the beacon are connected together, indicating that the train has passed the beacon when the VOBC receives the beacon information. During the train positioning establishment process, Distance_Offset = 0.

[0235] If the beacon is read in the sidelobe area and the train has already established positioning, the calculation method of Distance_Offset is as follows:

[0236] Based on the train position when the VOBC receives the beacon information sent by the beacon reader, calculate the train position when the beacon reader reads the beacon. The calculation method is: move the train position when receiving the beacon information sent by the beacon reader in the reverse direction of train operation by the beacon compensation distance (Compensation_Distance, which is the beacon compensation length measured when reading the beacon calculated in step five) to obtain the position.

[0237] Calculate the distance Distance_Offset from the train position when the beacon reader reads the beacon to the beacon position obtained from the on-vehicle electronic map.

[0238] In the running direction of the train, if the train position when the beacon reader reads the beacon is behind the beacon position obtained from the on-vehicle electronic map, then Detection_Offset = Distance_Offset; otherwise, Detection_Offset = -Distance_Offset.

[0239] Appendix Fig. 9 Indicates the calculation method of Distance_Offset when the beacon is read in the sidelobe area and the train has established positioning.

[0240] Finally, the VOBC updates the train position according to the beacon position Tag_Position, the beacon detection offset Detection_Offset, and the beacon compensation distance Compensation_Distance, that is, the train position is updated to:

[0241] Train_Position = Tag_Position - Detection_Offset + Compensation_Distance.

[0242] Appendix Fig.10 Indicates the train positioning update method in this embodiment.

[0243] When the VOBC determines that the beacon is read in the sidelobe area, after updating the train positioning, the position uncertainty of the train needs to increase the train positioning error value. The specific processing is as follows:

[0244] If Contact_Length < MIN_CONTACT_LENGTH, the position uncertainty of the train needs to increase by SIDE_LOBE_ERROR_MIN_CL;

[0245] If Contact_Length>MAX_CONTACT_LENGTH, the train's position uncertainty needs to be increased by SIDE_LOBE_ERROR_MAX_CL.

[0246] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for beacon sidelobe detection and improving train positioning accuracy, characterized in that: include: Step S1, obtaining the pulse count of the speed sensor through the beacon reader; Step S2, the beacon reader uses radio frequency energy to read beacon data from the beacons installed on the track; Step S3, the beacon reader sends beacon reading information to VOBC; Step S4, VOBC calculates train positioning data according to beacon information; Step S5, VOBC detects beacon side lobes according to train positioning data; Step S6, VOBC updates the train position.

2. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 1, characterized in that: The step S1 comprises: Step S11, adding a communication interface from VOBC to beacon reader between VOBC and beacon reader; Step S12, VOBC calculates pulse count according to wheel speed pulse output by speed sensor; Step S13, VOBC sends the pulse count to the beacon reader at a predetermined period.

3. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 2, characterized in that: In step S13, the period of VOBC sending pulse count to the beacon reader is consistent with the beacon reading processing period of the beacon reader. At the beginning of each beacon reading processing period, the beacon reader receives the pulse count value sent by VOB C and saves it as the current pulse count of the train, recorded as Train_Current_Pulse_Count.

4. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 1, characterized in that: The step S2 comprises: Step S21, the beacon reader first determines whether the radio frequency signal strength exceeds the beacon reading signal strength threshold for the first time in each beacon reading cycle; Step S22, if it is determined that the RF signal strength exceeds the beacon reading signal strength threshold for the first time, the beacon reader sets the beacon reading flag and saves the current pulse count of the train as the beacon reading start pulse count, recorded as Pulse_Count_Read_Start, that is, Pulse_Count_Read_Start = Train_Current_Pulse_Count; Step S23, the beacon reader will start to receive and decode the uplink signal. If the beacon data can be correctly obtained, the current pulse count of the train will be saved as the beacon read pulse count, recorded as Pulse_Count_Read_Tag, that is, Pulse_Count_Read_Tag = Train_Current_Pulse_Count; Step S24, saving the beacon reading pulse count and beacon data combination into a beacon reading result list; Step S25, if it is determined that the RF signal strength does not exceed the beacon reading signal strength threshold for the first time, then determine whether the RF signal strength exceeds the beacon reading signal strength threshold; Step S26, if the RF signal strength exceeds the beacon reading signal strength threshold, the beacon reader continues to receive and decode the uplink signal; Step S27: If the beacon data can be correctly obtained and the beacon data is different from the beacon data in the beacon reading result list, the current pulse count of the train is saved as the beacon reading pulse count, that is, Pulse_Count_Read_Tag, Pulse_Count_Read_Tag = Train_Current_Pulse_Count; Step S28, if the RF signal strength is less than the beacon reading signal strength threshold and the beacon reading flag is valid, clear the beacon reading flag, save the train current pulse count as the beacon reading end pulse count, recorded as Pulse_Count_Read_End, that is, Pulse_Count_Read_End = Train_Current_Pulse_Count; Step S29, then determine whether the beacon data is read. If the beacon data is read, that is, the beacon reading result list is not empty, then save the beacon reading start pulse count Pulse_Count_Read_Start, the beacon reading end pulse count Pulse_Count_Read_End and the data in the beacon reading result list to the beacon information sending queue, and clear the data in the beacon reading result list.

5. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 4, characterized in that: In step S29, the structure of each element of the beacon message sending queue is: {Pulse_Count_Read_Start,Pulse_Count_Read_End, {{Pulse_Count_Read_Tag_1, beacon data _1},{Pulse_Count_Read_Tag_2, beacon data _2}, …, {{Pulse_Count_Read_Tag_N, Beacon_Data_N}}}.

6. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 1, characterized in that: In step S3, the beacon reader sends a communication message to the VOBC according to a predetermined communication cycle. If the beacon message sending queue is not empty, the beacon reader sequentially takes out beacon information from the beacon message sending queue and sends it to the VOBC. The beacon reader sends the following data to VOBC in sequence according to the communication cycle: {Pulse_Count_Read_Start, Pulse_Count_Read_End, Pulse_Count_Read_Tag_i, beacon_data_i}, i=1,2,…,N; Each beacon information sent to VOBC includes a beacon read start pulse count, a beacon read end pulse count, a beacon read pulse count and beacon data.

7. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 1, characterized in that: In step S4, when the VOBC receives the beacon information sent by the beacon reader, it performs the following processing according to the pulse count of the speedometer: Calculate the beacon contact length Contact_Length read by the beacon according to the following formula: Calculate the beacon compensation distance Compensation_Distance according to the following formula: Where, π is the circumference of a circle, D is the wheel diameter of the train, Pulse_Count_Read_Start is the beacon reading start pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_End is the beacon reading end pulse count sent by the beacon reader to VOBC, Pulse_Count_Read_Tag is the beacon reading pulse count sent by the beacon reader to VOBC, Pulse_Count_Current is the pulse count calculated based on the wheel speed pulse output by the speed sensor when VOBC receives the beacon information sent by the beacon reader, N_Pulse_Count_Per_Wheel_Revolution is the number of pulses corresponding to one rotation of the train wheel, which is a fixed parameter of the system and is related to the technical specifications of the speed sensor; In step S5, VOBC determines whether the beacon is within the length range of the main lobe region according to the beacon contact length when the beacon is read, and can determine whether the beacon is read in the side lobe region or in the main lobe region, that is: Determine the length range of the main lobe area read by the beacon based on the relevant technical specifications of the beacon reader and actual physical measurements combined with actual test data analysis; The minimum beacon contact length MIN_CONTACT_LENGTH and the maximum beacon contact length MAX_CONTACT_LENGTH of the main lobe area, the length range of the main lobe area of ​​the beacon is: [MIN_CONTACT_LENGTH, MAX_CONTACT_LENGTH]; If satisfied: MIN_CONTACT_LENGTH≤Contact_Length≤MAX_CONTACT_LENGTH; Then it is determined that the beacon is read in the main lobe area, otherwise it is determined that there are side lobes in the beacon reading process, that is, the beacon may be read in the side lobe area; When VOBC determines that the beacon is read in the sidelobe area, VOBC sends an alarm message to ATS, indicating that the beacon sidelobe is detected. The operation and maintenance personnel determine whether the beacon reader equipment needs to be maintained based on the alarm prompt frequency. Among them, Contact_Length is the beacon contact length measured when the beacon is read.

8. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 1, characterized in that: The step S6 comprises: Step S61, VOBC obtains beacon identification information according to beacon data sent by the beacon reader, and VOBC determines whether the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon; Step S62, if it is determined that the train position has been updated using the beacon information detected in the main lobe area of ​​the beacon, the train position is no longer updated using the beacon information; Step S63: If it is determined that the train position has not been updated using the beacon information detected in the main lobe area of ​​the beacon, the beacon position Tag_Position is obtained from the on-board electronic map according to the beacon identifier, and then the beacon detection offset Detection_Offset is determined.

9. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 8, characterized in that: In step S63, if the beacon is read in the main lobe region, the calculation method of Detection_Offset is as follows: Detection_Offset = Contact_Length × X; In the formula, X is a fixed parameter, and its value is a decimal between -1 and 1. The value is determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with the analysis of actual test data; If the beacon is read in the side lobe region and the train has not established positioning, it means that the beacon is read in the side lobe region during the train positioning establishment process. It is processed in the following two cases: If Contact_Length < MIN_CONTACT_LENGTH, it means that the beacon is read in the side lobe region. When it is impossible to determine whether the train has passed the beacon when the VOBC receives the beacon information, the beacon information read in the side lobe region during the train positioning establishment process is not used to update the train position, and this processing ends; If Contact_Length > MAX_CONTACT_LENGTH, it means that the side lobe region and the main lobe region of the beacon are connected together, indicating that the train has passed the beacon when the VOBC receives the beacon information. During the train positioning establishment process, Distance_Offset = 0.

10. A method for beacon sidelobe detection and improving train positioning accuracy according to claim 9, characterized in that: In step S63, if the beacon is read in the side lobe region and the train has already established positioning, the calculation method of Distance_Offset is as follows: The VOBC calculates the train position when the beacon reader reads the beacon according to the train position when receiving the beacon information sent by the beacon reader. The calculation method is: The position obtained by moving the beacon compensation distance in the reverse direction of the train operation from the train position when receiving the beacon information sent by the beacon reader; Calculate the distance Distance_Offset from the train position when the beacon reader reads the beacon to the beacon position obtained from the on-vehicle electronic map; In the running direction of the train, if the train position when the beacon reader reads the beacon is behind the beacon position obtained from the on-vehicle electronic map, then Detection_Offset = Distance_Offset, otherwise Detection_Offset = -Distance_Offset; Finally, the VOBC updates the train position according to the beacon position Tag_Position, the beacon detection offset Detection_Offset, and the beacon compensation distance Compensation_Distance, that is, the train position is updated to: Train_Position = Tag_Position - Detection_Offset + Compensation_Distance; When the VOBC determines that the beacon is read in the side lobe region, after updating the train positioning, the position uncertainty of the train needs to increase the train positioning error value. The specific processing is as follows: If Contact_Length < MIN_CONTACT_LENGTH, the position uncertainty of the train needs to be increased by SIDE_LOBE_ERROR_MIN_CL; If Contact_Length > MAX_CONTACT_LENGTH, the position uncertainty of the train needs to be increased by SIDE_LOBE_ERROR_MAX_CL; Among them, SIDE_LOBE_ERROR_MIN_CL and SIDE_LOBE_ERROR_MAX_CL are determined according to the relevant technical specifications of the beacon reader, actual physical measurements, and combined with the analysis of actual test data.

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