Positioning method and system based on BDS and INS mutual feedback closed-loop correction

Abstract

The invention relates to a positioning method and system based on BDS and INS mutual feedback closed-loop correction, and the method comprises the steps: continuously collecting Beidou satellite positioning data for multiple times based on a Beidou satellite navigation system BDS, and determining an inertial navigation initial position through weighted average; in combination with inertial navigation system (INS) and Beidou satellite positioning (BDS) data, updating to obtain a high-precision position through combined filtering model dynamic error correction and vector average compensation, and taking the high-precision position as a navigation starting point; in the effective area of the Beidou satellite, an inertial navigation system (INS) navigates from a navigation starting point; in a Beidou satellite failure area, inertial navigation error compensation is performed based on an error vector of a position output by an inertial navigation system (INS) at a failure moment and a final high-precision position before the failure moment. Compared with the prior art, the method has the advantages that error accumulation of an inertial navigation system can be avoided, and high positioning precision can be kept when Beidou satellite signals are lost.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit positioning, and in particular to a high-precision train positioning method and system based on mutual feedback closed-loop calibration between BDS and INS. Background Art

[0002] Rail transit is experiencing rapid development globally and has become an important part of urban and regional transportation systems. With the acceleration of urbanization and the enhancement of environmental protection awareness, countries have invested in the construction of rail transit projects such as subways, light rails, and high-speed railways to alleviate traffic congestion, reduce carbon emissions, and improve the efficiency of public transportation. Technological advancements, such as automated driving and intelligent control systems, have also made rail transit safer, more efficient, and more convenient. At the same time, the expansion and interconnection of rail transit networks are improving regional connections and promoting the sustainable development of the economy and society. China is particularly prominent in this field, with the world's largest high-speed rail network and continuously promoting the innovation and application of rail transit technologies. In current rail transit operations, accurate train positioning is the basis for ensuring the safe operation of the railway. The rail transit precise positioning method based on the mutual correction of inertial navigation positioning and Beidou satellite positioning will help reduce positioning errors and improve positioning accuracy by compensating for errors in the Beidou satellite failure area, thus promoting and facilitating the development of rail transit.

[0003] At the present stage, the main positioning methods for rail transit are track circuit and transponder positioning. The track circuit positioning method is to install circuits in sections on the track. When the train passes, the circuit state changes, so as to judge the position of the train. However, the track circuit can usually only determine the position of the train within a specific section and is difficult to be accurate to the specific position of the train head or tail, which is not suitable for scenarios with high-precision requirements and is greatly affected by the environment and vulnerable to the influence of the external environment (such as weather, humidity, stray current, etc.), which may affect the accuracy and reliability of positioning. The transponder positioning method is to install transponders at fixed positions on the track. The on-board equipment on the train can accurately determine the specific position of the train by communicating with the transponders. However, this method also has certain defects. When the train is running between two transponders, the real-time position of the train cannot be obtained, and the positioning accuracy is very limited at this time. And when the train is in an area without Beidou satellite signals (tunnels, mountains, etc.) and only relies on the inertial navigation system for train positioning, the positioning accuracy is very limited at this time. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a precise rail transit positioning method combining inertial navigation positioning and Beidou satellite positioning.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] As a first aspect of the present invention, a positioning method based on closed-loop correction of mutual feedback between BDS and INS is provided, the method comprising the following steps:

[0007] Based on the BeiDou satellite navigation system (BDS), multiple BeiDou satellite positioning data are continuously collected and the initial inertial navigation position is determined by weighted average;

[0008] Combining the inertial navigation system INS and BeiDou satellite positioning BDS data, the high-precision position is updated through the combined filter model dynamic error correction and vector average compensation, and used as the navigation starting point;

[0009] In the effective area of BeiDou satellites, the inertial navigation system INS navigates from the navigation starting point;

[0010] In the Beidou satellite failure area, inertial navigation error compensation is performed based on the error vector between the position output by the inertial navigation system INS at the time of failure and the final high-precision position before the failure.

[0011] As a preferred technical solution, the inertial navigation initial position calculation is specifically as follows:

[0012] When the inertial navigation system INS has zero output, the BeiDou satellite navigation system BDS receiver continuously collects multiple BeiDou satellite positioning data; the BeiDou satellite positioning data is multiplied by the weight and then summed to obtain the initial position P init :

[0013]

[0014] Among them, P BDS Beidou satellite positioning data; i is the weight coefficient.

[0015] As a preferred technical solution, the weight coefficients are assigned different weights according to the temporal characteristics of the positioning data:

[0016]

[0017] Wherein, α is the attenuation factor; i is the data sequence number, i=1,2,…,N.

[0018] As a preferred technical solution, the high-precision location update is specifically as follows:

[0019] The acceleration of the target is obtained through the inertial navigation positioning system, and the state transfer equation of the target is obtained:

[0020]

[0021] Among them, x k is the state vector of the train at time k; F is the state transfer matrix, B is the input control matrix; uk is the input matrix; w k is the process noise;

[0022] The observation equation of the target obtained by BeiDou satellite positioning is:

[0023] z k = Hx k + v k

[0024] where z k is the observation vector of the train at time k; H is the observation matrix; v k is the observation noise;

[0025] Using the inertial navigation position with high short-term accuracy, calculate the error value between the inertial navigation position and the BeiDou satellite navigation position. The equation for obtaining the error vector by combining the navigation positions is:

[0026]

[0027] Calculate the vector average value of the error values between the inertial navigation position and the BeiDou satellite navigation position within n time steps. The vector average value E k The update equation is:

[0028]

[0029] According to the calculated vector average value of the error values, update the high-precision position and use this as the starting point for inertial navigation, specifically as follows:

[0030] X k = z k + E k

[0031] where X k is the high-precision position.

[0032] As a preferred technical solution, the error compensation in the BeiDou failure area is specifically as follows:

[0033] Obtain the final high-precision position before the BeiDou signal fails

[0034] Calculate the position x output by the INS at the failure moment k and the final high-precision position error vector δ:

[0035]

[0036] During the failure period, compensate the INS output position at fixed time intervals:

[0037]

[0038] As a second aspect of the present invention, a positioning system based on mutual feedback closed-loop correction between BDS and INS is provided. The system includes:

[0039] A Beidou satellite positioning system BDS receiver that receives navigation signals from the Beidou satellite navigation system;

[0040] A Beidou satellite positioning system BDS filter that processes the received BDS signals to obtain preliminary positioning information;

[0041] An inertial navigation system that processes the received BDS signals to obtain preliminary positioning information;

[0042] A BDS / INS combined filter is connected to the Beidou satellite positioning system BDS filter and the inertial navigation system, and includes a state update module. When the Beidou satellite signal is valid, the combined filter weights and fuses the position information output by the Beidou satellite positioning system BDS and the inertial navigation system INS, and performs recursive update of the position state with the state estimation, system noise matrix, and observation noise matrix at the previous moment, and outputs the final combined navigation position information;

[0043] An inertial navigation error compensation module determines the availability of the Beidou satellite signal. When the Beidou satellite signal fails, it switches to the inertial navigation error compensation mode, uses the short-term accuracy of the inertial navigation system to estimate the error of the Beidou satellite position information to obtain a high-precision position, and uses the high-precision position as the starting point of the inertial navigation system again; compensates and corrects the output data of the inertial navigation system based on the error between the current position and the output data of the inertial navigation system, and provides the corrected inertial navigation position information.

[0044] As a preferred technical solution, the Beidou satellite positioning system BDS filter continuously collects multiple Beidou satellite positioning data when the inertial navigation system INS outputs zero; multiplies the Beidou satellite positioning data by weights and sums them to obtain the initial position P init :

[0045]

[0046] where P BDS is the Beidou satellite positioning data; ω i is the weight coefficient.

[0047] As a preferred technical solution, the weight coefficient assigns different weights according to the timing characteristics of the positioning data:

[0048]

[0049] Among them, α is the attenuation factor; i is the data sequence number, i = 1, 2, …, N.

[0050] As a preferred technical solution, the BDS / INS combined filter uses the short-term accuracy of the inertial navigation system to estimate the error of the Beidou satellite position information to obtain a high-precision position, specifically as follows:

[0051] Obtain the acceleration of the target through the inertial navigation positioning system, and obtain the state transition equation of the target:

[0052]

[0053] where, x k is the state vector of the train with respect to time k; F is the state transition matrix, B is the input control matrix; u k is the input matrix; w k is the process noise;

[0054] Obtain the observation equation of the target through Beidou satellite positioning:

[0055] z k = Hx k + v k

[0056] where, z k is the observation vector of the train with respect to time k; H is the observation matrix; v k is the observation noise;

[0057] Use the inertial navigation position with high short-term accuracy to calculate the error value between the inertial navigation position and the Beidou satellite navigation position. The equation for obtaining the error vector by combining the navigation positions is:

[0058]

[0059] Calculate the vector average value of the error values between the inertial navigation position and the Beidou satellite navigation position within n time steps. The vector average value E k The update equation is:

[0060]

[0061] According to the calculated vector average value of the error values, update the high-precision position and use this as the starting point for inertial navigation, specifically as follows:

[0062] X k = z k + E k

[0063] where, X k is the high-precision position.

[0064] As a preferred technical solution, the inertial navigation error compensation module is specifically as follows:

[0065] Obtain the final high-precision position before the Beidou signal fails

[0066] Calculate the position x output by the INS at the failure moment k And the final high-precision position The error vector δ:

[0067]

[0068] During the failure period, compensate the INS output position at fixed time intervals:

[0069]

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] 1) In the effective area of Beidou satellites, the present invention obtains approximate position information through the use of an inertial navigation system, combines the relatively accurate position information of Beidou satellite positioning, estimates the error of the Beidou satellite position information by utilizing the short-term accuracy of the inertial navigation system to obtain the accurate position, and uses the accurate position as the starting point of the inertial navigation system again to avoid the error accumulation of the inertial navigation system.

[0072] 2) In the Beidou satellite failure area, the present invention improves the positioning accuracy of the train through error compensation. Compared with the traditional track circuit positioning and transponder positioning, it avoids the disadvantage that the positioning has high accuracy only in specific sections. By combining filtering algorithms and multiple positionings, the positioning accuracy of the train is improved, and a high positioning accuracy can also be maintained when the Beidou satellite signal is lost. Description of the Drawings

[0073] Figure 1 It is a flowchart of a high-precision train positioning method based on Beidou satellite differential correction INS in an embodiment of the present invention;

[0074] Figure 2 It is a schematic diagram of a high-precision train positioning system based on Beidou satellite differential correction INS in an embodiment of the present invention;

[0075] Figure 3 It is a position map of positioning relying only on inertial navigation in an embodiment of the present invention;

[0076] Figure 4 It is an observation position map of Beidou satellite positioning in an embodiment of the present invention;

[0077] Figure 5Precision positioning map of rail transit combining inertial navigation positioning and Beidou satellite positioning in an embodiment of the present invention;

[0078] Figure 6 Inertial navigation positioning map with error correction in the Beidou satellite failure area in an embodiment of the present invention. Detailed implementation manners

[0079] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0080] Embodiment 1

[0081] In order to solve the problem that traditional positioning methods cannot have high precision, the present invention provides a precision positioning method for rail transit combining inertial navigation positioning and Beidou satellite positioning. As Figure 1 shown, for the Beidou satellite effective area, when the train passes through the positioning label at a fixed position, the speed, acceleration and position data of the train are obtained through inertial navigation positioning, so as to obtain a rough position; rely on Beidou satellite positioning to obtain a relatively accurate observed position; construct a filtering model, use the inertial navigation position with high short-term precision, and calculate the error value between the inertial navigation position and the Beidou satellite navigation position; calculate the vector average value of the error values within multiple time steps; according to the calculated vector average value, update the accurate position and use this as the starting point for inertial navigation; input the updated accurate position into the next moment, and repeat the steps of calculating the error and updating the accurate position. For the Beidou satellite failure area, when the train enters the Beidou satellite failure area, obtain the error value between the accurate position at the last moment before the train loses the Beidou satellite and the inertial navigation positioning position; rely on the obtained error value to correct the inertial navigation positioning position in the Beidou satellite failure area to obtain higher-precision position information. The specific steps include:

[0082] Determine the starting point of inertial navigation based on multiple weighted averages of Beidou satellites: When the inertial navigation system (INS) is in a zero-output state (such as when the system is started, restarted or initialized), the initial position needs to be determined through the Beidou satellite navigation system (BDS). In order to reduce the random error of BDS positioning, this embodiment uses a multiple weighted average method to obtain a high-precision starting point. The specific steps are as follows:

[0083] 1.1. Data acquisition:

[0084] When the inertial navigation system INS outputs zero, the Beidou satellite navigation system BDS receiver continuously acquires N times of Beidou satellite positioning data (N≥10), denoted as P BDS 1, P BDS 2,..., P BDS N.

[0085] 1.2, Weight Assignment:

[0086] According to the timing characteristics of the positioning data, different weights are assigned. The weight of the recent positioning data is higher to reflect the real-time nature of environmental changes. The weight coefficients are assigned according to exponential decay:

[0087]

[0088] where α is the decay factor (it is recommended to take values from 0.1 to 0.3), and i is the data serial number (i = 1, 2,..., N).

[0089] 1.3, Weighted Average Calculation:

[0090] Multiply the N - time positioning data by their weights and sum them up to obtain the initial position P init :

[0091]

[0092] 1.4, Starting Point Input:

[0093] Take the initial position P init as the initial position input of the inertial navigation system INS and start the inertial navigation system. At the same time, synchronize this initial position to the BDS / INS combined filter for subsequent integrated positioning.

[0094] Dynamic Error Correction and Position Update Based on the Combined Filter Model: In this embodiment, through the combined filter model, combining the data of the inertial navigation system (INS) and the Beidou satellite positioning system (BDS), high-precision position update is achieved through dynamic error correction and vector average compensation. The specific steps are as follows:

[0095] 2.1, Obtain the train acceleration through the inertial navigation positioning system to get the state transition equation of the train:

[0096]

[0097] where x k is the state vector of the train with respect to time k, F is the state transition matrix, B is the input control matrix, u k is the input matrix, w k is the process noise, and in this embodiment, zero - mean Gaussian noise is adopted.

[0098] 2.2, Obtain the observation equation of the train through Beidou satellite positioning:

[0099] z k = Hx k + v k

[0100] where z k is the observation vector of the train with respect to time k; H is the observation matrix; v k is the observation noise, and in this embodiment, Gaussian noise with zero mean is adopted.

[0101] 2.3. Calculate the error value between the inertial navigation position and the Beidou satellite navigation position using the inertial navigation position with high short-term accuracy. The equation for obtaining the error vector by combining the navigation positions is:

[0102]

[0103] 2.4. Calculate the vector average value of the error values between the two within 40 time steps. The update equation for the vector average value is:

[0104]

[0105] 2.5. Update the accurate position based on the calculated vector average value of the error values and perform inertial navigation starting from this point. The specific steps are as follows:

[0106] X k = z k + E k (k > 40).

[0107] Error compensation in the Beidou failure area: In the area where the Beidou satellite fails, the inertial navigation system INS navigates based on the initial position in step 1. When the signal fails, the inertial navigation error compensation module is activated and the following steps are executed:

[0108] 3.1. Obtain the final high-precision position before the Beidou signal fails

[0109] 3.2. Calculate the error vector δ between the position x k output by the INS at the failure moment and the final high-precision position :

[0110]

[0111] 3.3. During the failure period, compensate the INS output position at a fixed time interval (such as 1 second):

[0112]

[0113] Embodiment 2

[0114] As another implementation manner of the present invention, this embodiment provides a high-precision positioning device based on mutual feedback closed-loop correction between BDS and INS, such as Figure 2As shown in the figure, it includes: a BDS receiver, a BDS filter, an inertial navigation system (INS), a BDS / INS combined filter, and an inertial navigation error compensation module, where:

[0115] The BDS receiver is used to receive navigation signals from the Beidou satellite navigation system.

[0116] The BDS filter is used to process the received BDS signals to obtain preliminary positioning information;

[0117] The inertial navigation system includes an accelerometer, a gyroscope, and an inertial measurement unit, and is used to provide motion state information based on inertial measurements.

[0118] The BDS / INS combined filter is connected to the BDS filter and the inertial navigation system, and includes a state update module. When the Beidou satellite signal is valid, the combined filter is used to perform weighted fusion on the position information output by BDS and INS, and perform recursive update of the position state with the state estimation, system noise matrix, and observation noise matrix at the previous moment, and output the final combined navigation position information.

[0119] The inertial navigation error compensation module, through the determination of the availability of the Beidou satellite signal, switches to the INS error compensation mode when the Beidou satellite signal fails to ensure the continuity of positioning; when the Beidou satellite signal fails, continuously uses the short-term accuracy of the inertial navigation system to estimate the error of the Beidou satellite position information to obtain the accurate position, and uses the accurate position again as the starting point of the inertial navigation system to avoid the accumulation of errors in the inertial navigation system; compensates and corrects the output data of the inertial navigation system based on the error between the current position and the output data of the inertial navigation system, and provides the corrected inertial navigation position information.

[0120] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A positioning method based on mutual feedback closed-loop correction between BDS and INS, characterized in that, The method steps include: Continuously collect multiple Beidou satellite positioning data based on the Beidou Satellite Navigation System (BDS), and determine the initial position of inertial navigation through weighted average. Combine the Inertial Navigation System (INS) and Beidou satellite positioning (BDS) data, and update to obtain a high-precision position through combined filter model dynamic error correction and vector average compensation, which is used as the navigation starting point. In the effective area of Beidou satellites, the Inertial Navigation System (INS) is navigated from the navigation starting point. In the area where Beidou satellites fail, based on the error vector between the position output by the Inertial Navigation System (INS) at the failure moment and the final high-precision position before the failure moment, inertial navigation error compensation is performed.

2. The positioning method based on mutual feedback closed-loop correction between BDS and INS according to claim 1, characterized in that, The calculation of the initial position of inertial navigation is specifically as follows: When the inertial navigation system INS outputs zero, the Beidou satellite navigation system BDS receiver continuously collects Beidou satellite positioning data multiple times; the Beidou satellite positioning data is multiplied by weights and then summed to obtain the initial position P init : Among them, P BDS is the Beidou satellite positioning data; ω i is the weight coefficient.

3. A positioning method based on mutual feedback closed-loop correction between BDS and INS according to claim 2, characterized in that, The weight coefficients are given different weights according to the timing characteristics of the positioning data: Where α is the attenuation factor; i is the data serial number, i = 1, 2,..., N.

4. A positioning method based on mutual feedback closed-loop correction between BDS and INS according to claim 1, characterized in that The update of the high-precision position is specifically as follows: Obtain the acceleration of the target through the inertial navigation positioning system, and obtain the state transition equation of the target: where x k is the state vector of the train with respect to time k; F is the state transition matrix, and B is the input control matrix; u k is the input matrix; w k is the process noise; Obtain the observation equation of the target through Beidou satellite positioning: z k = Hx k + v k where, z k is the observation vector of the train with respect to time k; H is the observation matrix; v k is the observation noise; Use the inertial navigation position with high short-term accuracy to calculate the error value between the inertial navigation position and the Beidou satellite navigation position. The equation for obtaining the error vector by combining the navigation positions is: Calculate the vector average value of the error between the inertial navigation position and the Beidou satellite navigation position within n time steps, and the vector average value is E k The update equation is as follows: According to the vector average value of the calculated error value, update the high-precision position and use this as the starting point for inertial navigation, specifically as follows: X k = z k + E k Among them, X k is a high-precision position.

5. A positioning method based on mutual feedback closed-loop correction between BDS and INS according to claim 1, characterized in that, The error compensation in the Beidou failure area is specifically as follows: Obtain the final high-precision position before the Beidou signal fails Calculate the position x output by the INS at the failure moment k and the final high-precision position The error vector δ of: During the failure period, compensate the INS output position at fixed time intervals:

6. A positioning system based on mutual feedback closed-loop correction between BDS and INS, characterized in that, The system includes: A Beidou Satellite Navigation System (BDS) receiver that receives navigation signals from the Beidou Satellite Navigation System; A Beidou Satellite Navigation System (BDS) filter that processes the received BDS signals to obtain preliminary positioning information; An inertial navigation system that processes the received BDS signals to obtain preliminary positioning information; A BDS / INS combined filter, which is connected to the Beidou Satellite Navigation System (BDS) filter and the inertial navigation system. It includes a state update module. When the Beidou satellite signal is valid, the combined filter performs weighted fusion on the position information output by the Beidou Satellite Navigation System (BDS) and the inertial navigation system (INS), and performs recursive update of the position state with the state estimation, system noise matrix, and observation noise matrix at the previous moment, and outputs the final combined navigation position information; An inertial navigation error compensation module that determines the availability of Beidou satellite signals. When the Beidou satellite signal fails, it switches to the inertial navigation error compensation mode. It uses the short-term accuracy of the inertial navigation system to estimate the error of the Beidou satellite position information to obtain a high-precision position, and uses the high-precision position as the starting point of the inertial navigation system again; based on the error between the current position and the output data of the inertial navigation system, it compensates and corrects the output data of the inertial navigation system, and provides the corrected inertial navigation position information.

7. A positioning system based on mutual feedback closed-loop correction between BDS and INS according to claim 6, characterized in that, The BDS filter of the Beidou satellite positioning system continuously collects Beidou satellite positioning data multiple times when the inertial navigation system (INS) has zero output; the Beidou satellite positioning data is multiplied by weights and then summed to obtain the initial position P init : Among them, P BDS is the Beidou satellite positioning data; ω i is the weight coefficient.

8. A positioning system based on mutual feedback closed-loop correction between BDS and INS according to claim 7, characterized in that, The weight coefficients are given different weights according to the timing characteristics of the positioning data: Where α is the attenuation factor; i is the data serial number, i = 1, 2,..., N.

9. A positioning system based on mutual feedback closed-loop correction between BDS and INS according to claim 6, characterized in that, The BDS / INS combined filter uses the short-term accuracy of the inertial navigation system to estimate the error of the Beidou satellite position information to obtain a high-precision position, as follows: Obtain the acceleration of the target through the inertial navigation positioning system, and obtain the state transition equation of the target: where x k is the state vector of the train with respect to time k; F is the state transition matrix, B is the input control matrix; u k is the input matrix; w k is the process noise; Obtain the observation equation of the target through Beidou satellite positioning: z k = Hx k + v k where z k is the observation vector of the train with respect to time k; H is the observation matrix; v k is the observation noise; Use the inertial navigation position with high short-term accuracy to calculate the error value between the inertial navigation position and the Beidou satellite navigation position. The equation for obtaining the error vector by combining the navigation positions is: Calculate the vector average value of the error between the inertial navigation position and the Beidou satellite navigation position within n time steps, and the vector average value is E k The update equation is as follows: According to the vector average value of the calculated error value, update the high-precision position and use this as the starting point for inertial navigation, as follows: X k = z k + E k Among them, X k is a high-precision position.

10. A positioning system based on mutual feedback closed-loop correction between BDS and INS according to claim 6, characterized in that, The inertial navigation error compensation module is as follows: Obtain the final high-precision position before the Beidou signal fails Calculate the position x output by the INS at the failure moment k and the final high-precision position The error vector δ of: During the failure period, compensate the INS output position at fixed time intervals:

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