Method and device for realizing time synchronization of integrated navigation system

Abstract

The present application discloses a method and apparatus for achieving time synchronization of an integrated navigation system. By using the 1PPS pulse per second generated by a GNSS receiver as the time reference, the sampling time generated by an INS device is calibrated, and the time tags of the GNSS and INS systems are unified into the same time coordinate system. This method enables the time synchronization of the GNSS and INS integrated navigation system to have high accuracy and good real-time performance.

Description

Technical Field

[0001] The present application relates to, but is not limited to, satellite navigation technology, and in particular to a method and device for implementing time synchronization in an integrated navigation system. Background Art

[0002] With the development of the intelligent driving industry, high-precision positioning technology has ushered in new development opportunities. High-level autonomous driving requires increasingly higher positioning accuracy. Satellite navigation is the most commonly used method for high-precision positioning. However, satellite navigation cannot consistently produce high-precision positioning results in environments such as tall buildings and shaded by trees. Therefore, single satellite navigation is no longer sufficient to meet these high-precision positioning requirements. Inertial navigation, with its independence, autonomy, and immunity to external interference, perfectly complements satellite navigation technology.

[0003] The basic principle of a combined navigation system combining satellite navigation systems (GNSS, Global Navigation Satellite System) and inertial navigation systems (INS) is to achieve high-precision, high-reliability navigation and positioning by combining the strengths of both systems. GNSS is a system that receives and broadcasts electromagnetic signals for navigation, positioning, and timing (PNT) purposes and relies on a high-orbit satellite system. INS is a navigation system based on the principles of inertial mechanics, calculating position, velocity, and attitude by measuring acceleration and angular velocity. GNSS provides long-term, high-precision position information, while INS provides short-term, high-precision attitude information. The accuracy of combined GNSS and INS positioning depends on both the individual positioning accuracies of the GNSS and INS and the synchronization and timing accuracy of the satellite navigation observation data with the inertial navigation observation data.

[0004] Currently, there are two common approaches to high-precision timing synchronization. One is hardware time synchronization based on a processor and a pulse per second (PPS) signal. This requires strict alignment of the satellite navigation signal sampling timescale with the inertial navigation data acquisition timescale. Furthermore, hardware time synchronization requires a high-performance processor chip, which increases hardware costs and makes it unsuitable for widespread use. The other is software time synchronization using Coordinated Universal Time (UTC) and the PPS signal. Software time synchronization unifies different sensor data sources into a common time coordinate system (i.e., using a unified time system). Compared to hardware time synchronization, software time synchronization converts the data collection time into the data reception time. By increasing the priority of satellite navigation data and INS data processing in the processor, it can also achieve more stable time synchronization. However, it cannot eliminate errors caused by time asynchrony when fusing different data sources, thus failing to guarantee synchronization accuracy. Summary of the Invention

[0005] The present application provides a method and device for implementing time synchronization in an integrated navigation system, which can improve the accuracy of time synchronization.

[0006] An embodiment of the present invention provides a method for implementing time synchronization in an integrated navigation system, comprising:

[0007] When the first pulse per second (PPS) signal arrives, the local PPS time and time quality are obtained; when the inertial navigation system (INS) data is ready after the first PPS signal and before the second PPS signal arrives, the INS data and INS time are obtained; the obtained local PPS time, time quality, and INS time are stored in the time synchronization data set;

[0008] When the second PPS signal arrives, obtain the local PPS time and time quality. After the second PPS signal and before the third PPS signal arrives, when the INS data is ready, obtain the INS data and INS time. Store the obtained local PPS time, time quality, and INS time in the time synchronization data set.

[0009] For arrays with the same time quality in the time synchronization data set, the phase offset of the INS time is calculated based on the local PPS time and INS time in the array; for arrays with accurate time quality in the time synchronization data set, the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality is calculated;

[0010] The time of the INS data at the moment when the second PPS signal arrives is synchronized according to the calculated phase offset and time difference.

[0011] An embodiment of the present application further provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute any one of the above methods for implementing time synchronization in a combined navigation system.

[0012] An embodiment of the present application further provides a device for implementing time synchronization of an integrated navigation system, comprising a memory and a processor, wherein the memory stores the following instructions executable by the processor: for executing the steps of any of the above-mentioned methods for implementing time synchronization of an integrated navigation system.

[0013] The embodiment of the present application further provides a device for realizing time synchronization of an integrated navigation system, comprising: an acquisition module, a processing module, and a synchronization module; wherein,

[0014] an acquisition module, configured to acquire local PPS time and time quality upon arrival of a first PPS signal; acquire INS data and INS time after the first PPS signal and before the arrival of a second PPS signal, when INS data is ready; store the acquired local PPS time, time quality, and INS time in a time synchronization data set; acquire local PPS time and time quality upon arrival of a second PPS signal; acquire INS data and INS time after the second PPS signal and before the arrival of a third PPS signal, when INS data is ready; store the acquired local PPS time, time quality, and INS time in the time synchronization data set;

[0015] a processing module configured to calculate, for arrays with the same time quality in the time synchronization data set, a phase offset of the INS time based on the local PPS time and the INS time in the array; and, for arrays with precise time quality in the time synchronization data set, calculate a time difference between the INS time at which the second PPS signal arrives and the INS time in the array with precise time quality;

[0016] The synchronization module is used to synchronize the time of the INS data at the arrival moment of the second PPS signal according to the calculated phase offset and time difference.

[0017] The embodiment of the present application uses the 1PPS pulse per second generated by the GNSS receiver as the time reference to calibrate the sampling time generated by the INS device, and unifies the time tags of the two systems to the same time coordinate system, so that the time synchronization accuracy of the GNSS and INS combined navigation system is high and the real-time performance is good.

[0018] Furthermore, the embodiments of the present application can perform real-time correction when the sampling time reference of the INS device drifts, eliminating the error caused by time asynchrony when different data sources are fused, thereby improving the optimal estimation of state quantities such as attitude, velocity and position of the integrated navigation system.

[0019] Furthermore, after achieving synchronization of INS time and GNSS time to obtain INS time and GNSS time in the same time coordinate system, the embodiment of the present application further performs time error compensation on INS velocity information and INS position information, and uses the INS velocity information and INS position information after time error compensation to perform combined navigation processing. In this way, the problem of system status information mismatch caused by time asynchrony is reduced.

[0020] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0022] Figure 1 A flowchart of a method for implementing time synchronization in a combined navigation system according to an embodiment of the present application;

[0023] Figure 2 This is a schematic diagram of an embodiment of the working principle of the combined navigation system for achieving time synchronization in an embodiment of the present application;

[0024] Figure 3 This is a structural diagram of a device for implementing time synchronization in a combined navigation system according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0026] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0028] It is understood that the terms "first" and "second" used in this application are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0029] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0030] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0031] Figure 1 This is a flow chart of a method for implementing time synchronization in a combined navigation system according to an embodiment of the present application. Figure 1 As shown, including:

[0032] Step 100: When the first PPS signal arrives, obtain the local PPS time and time quality; after the first PPS signal and before the second PPS signal arrives, when the INS data is ready, obtain INS data and INS time; store the obtained local PPS time, time quality, and INS time in the time synchronization data set.

[0033] In an exemplary embodiment, the following steps may be included before step 100:

[0034] The GNSS receiver synchronizes with the GNSS satellite system clock to calibrate the clock;

[0035] A GNSS receiver outputs a PPS signal at precise intervals based on its own calibrated clock. The receiver maintains the accuracy of the PPS signal at the moment it is emitted. In one embodiment, the rising edge of the PPS signal can be used to indicate the full second of UTC, achieving nanosecond accuracy.

[0036] In an exemplary embodiment, when the first PPS signal arrives, obtaining the local PPS time and time quality in step 100 may include:

[0037] The GNSS receiver's processor monitors the PPS signal in real time. When the first PPS signal arrives, such as a rising edge, it latches the local PPS time and stores it in the INS-related information (INSPPS). The local PPS time can be represented as PPS.PPSTime (PPS signal arrival time), which represents the UTC time when the GNSS receiver module in the GNSS receiver generates the PPS signal. In one embodiment, the time quality can be represented as PPS.TimeQuality (PPS signal arrival time). The current time quality is determined based on the GNSS receiver algorithm and can be classified as Accurate, Coarse, or Unknown.

[0038] In an exemplary embodiment, after the first PPS signal arrives and before the second PPS signal arrives, when the INS data is ready, obtaining the INS data and INS time in step 100 may include:

[0039] When the INS data is ready, the INS data and INS time are read. The INS data can be represented as INS.GYOACC (INS data ready time), and the INS time can be represented as INS.INSTime (INS data ready time). In one embodiment, the INS time is maintained by the INS sensor itself and is the internal time of the INS sensor.

[0040] In an exemplary embodiment, the time synchronization data set may be a pre-set structure array, which may be represented as INS_PPSTimeSyncInfo[]. A structure array is a data type that groups related data together using a data container called a field.

[0041] It should be noted that the INS data ready in step 100 may be a cyclically executed process, that is, as long as the INS data is ready, the INS data and INS time will be recorded.

[0042] like Figure 2In the illustrated embodiment, assuming that the first PPS signal arrives at time T1, the PPS time PPS.PPSTime(T1) and the time quality PPS.TimeQuality(T1) are recorded, and the PPS time PPS.PPSTime(T1) and the time quality PPS.TimeQuality(T1) are saved to the INS-related information INSPPS, and INSPPS.PPSTime(T1) and INSPPS.TimeQuality(T1) are updated; here, INSPPS.PPSTime(T1) is PPS.PPSTime(T1), which represents the UTC time when the GNSS receiving module in the corresponding GNSS receiver generates the PPS signal when the first PPS signal arrives at time T1. INSPPS.TimeQuality(T1) is PPS.TimeQuality(T1), which represents the time quality at time T1 and can be divided into three types: Accurate, oarse, and Unknown.

[0043] In this embodiment, the INS data is ready at time T2, and the INS data INS.GYOACC(T2) and the INS time INS.INSTime(T2) are read; INS_PPSTimeSyncInfo[0] is updated at time T2, and the PPSTime(T1), TimeQuality(T1) and INSTime(T2) at this time are stored.

[0044] It should be noted that the typical PPS pulse output is 1Hz, and the INS Data acquisition frequency is higher than 1Hz. Therefore, there may be multiple INS data ready times between T1 and T3. The INS_PPSTimeSyncInfo[] above will record the INSTime, PPSTime, and TimeQuality of each INS data ready time. After the PPS and INS Data are synchronized, the calculated time offset value is applied to subsequent INS Data until the next PPS pulse arrives, at which point the INS Data time offset value is updated.

[0045] Step 101: When the second PPS signal arrives, obtain the local PPS time and time quality. After the second PPS signal and before the third PPS signal arrives, when the INS data is ready, obtain INS data and INS time; store the obtained local PPS time, time quality, and INS time in the time synchronization data set.

[0046] In an exemplary embodiment, the second PPS signal is a next PPS signal of the first PPS signal. The third PPS signal is a next PPS signal of the second PPS signal.

[0047] like Figure 2 In the illustrated embodiment, assuming that the second PPS signal arrives at time T3, PPS.PPSTime(T3) and PPS.TimeQuality(T3) are recorded;

[0048] In this embodiment, at time T4, the INS data is ready, and the INS data INS.GYOACC(T4) and the INS time INS.INSTime(T4) are read; at time T4, INS_PPSTimeSyncInfo[0], PPSTime(T3), TimeQuality(T3) and INSTime(T4) are updated in sequence, and the INS_PPSTimeSyncInfo[0] information stored at time T2, namely PPSTime(T1), TimeQuality(T1) and INSTime(T2), are copied and moved backward (i.e., toward the end of the time synchronization data set INS_PPSTimeSyncInfo[]) to INS_PPSTimeSyncInfo[1].

[0049] Step 102: For arrays with the same time quality in the time synchronization data set, calculate the phase offset of the INS time based on the local PPS time and INS time in the array; for arrays with accurate time quality in the time synchronization data set, calculate the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality.

[0050] In one exemplary embodiment, calculating the phase offset of the INS time in step 102 may include:

[0051] Starting from the array at the end of the storage of the time synchronization data set, compare the time quality of the array with the array when the current INS data is ready, record the array number i of the first array with the same time quality as the array when the current INS data is ready, and calculate the phase offset of the INS time according to formula (1):

[0052]

[0053] The calculations of dt_PPS and dt_INS in formula (1) are shown in formula (2) and formula (3), respectively:

[0054] dt_PPS=INS_PPSTimeSyncInfo[0].PPSTime-INS_PPSTimeSyncInfo[i].PPSTime(2)

[0055] dt_INS=INS_PPSTimeSyncInfo[0].INSTime-INS_PPSTimeSyncInfo[i].INSTime(3)

[0056] In formula (2) and formula (3), i is an integer greater than or equal to 1.

[0057] Among them, dt_PPS represents the difference between the PPS time INS_PPSTimeSyncInfo[0].PPSTime in the array when the current INS data is ready and the PPS time INS_PPSTimeSyncInfo[i].PPSTime in the array i with the same time quality as the array when the current INS data is ready.

[0058] dt_INS represents the difference between the INS time INS_PPSTimeSyncInfo[0].INSTime in the array when the current INS data is ready and the INS time INS_PPSTimeSyncInfo[i].INSTime in array i having the same time quality as that in the array when the current INS data is ready.

[0059] like Figure 2 In the illustrated embodiment, for the time synchronization data set INS_PPSTimeSyncInfo[], starting from the array at the end of the storage, the time qualities are compared with those in INS_PPSTimeSyncInfo[0] respectively. For the first array with the same time quality TimeQuality, the array number i of the array is recorded, and the phase offset of the INS time at time T4 is calculated according to formula (1).

[0060] In an exemplary embodiment, calculating the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality in step 102 may include:

[0061] From the arrays in the time synchronization dataset, excluding the array for the current INS data being ready, starting from the array at the end of the storage of the time synchronization dataset, search for the first array that includes a time quality of Accurate, and calculate the difference between the INS time in the array for the current INS data being ready and the INS time in the found array.

[0062] like Figure 2In the illustrated embodiment, starting from the array at the end of the storage of the time synchronization data set, the data of the first array whose time quality TimeQuality is Accurate is searched, and the array number j is recorded; as shown in formula (4), the difference between the INS time in INS_PPSTimeSyncInfo[0] and the INS time in INS_PPSTimeSyncInfo[j] is calculated.

[0063] dt=INS_INSTime(T4)-INS_PPSTimeSyncInfo[j].INSTime (4)

[0064] It should be noted that there is no strict order in which the phase offset of the INS time is calculated in step 102 and the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality is calculated in step 102 .

[0065] Step 103: Synchronize the time of the INS data at the arrival moment of the second PPS signal according to the calculated phase offset and time difference.

[0066] In an exemplary embodiment, the time of the INS data at the INS data ready moment, i.e., the second PPS signal arrival moment, is synchronized according to formula (5):

[0067] INS.Time=INS_PPSTimeSyncInfo[j].ppstime+dt*(1+INSClkDrfit) (5)

[0068] In formula (5), INS_PPSTimeSyncInfo[j].PPSTime indicates the PPS time in the first array of Accurate whose time quality TimeQuality is accurate. The INS.Time calculated by formula (5) has converted the INS time to GNSS time, thus achieving synchronization between INS time and GNSS time.

[0069] The method for achieving time synchronization of the integrated navigation system provided in the embodiment of the present application calibrates the sampling time generated by the INS device by using the 1PPS pulse per second generated by the GNSS receiver as the time reference, and unifies the time tags of the GNSS and INS systems to the same time coordinate system, thereby achieving high time synchronization accuracy and good real-time performance of the GNSS and INS integrated navigation system.

[0070] In one exemplary embodiment, before the third PPS signal arrives, each time the INS data is ready, the process further includes: using the phase offset calculated in step 102 as the INS time offset to perform time synchronization calibration, i.e., synchronizing the time of the INS data. This embodiment of the present application enables real-time correction when the sampling time reference of the INS device drifts, eliminating errors caused by time asynchrony when fusing different data sources, thereby improving the optimal estimation of state quantities such as attitude, velocity, and position of the integrated navigation system.

[0071] In an exemplary embodiment, if the subsequent PPS signal is unavailable, the INS may continue to use the INSClkDrfit calculated in step 102 to correct the time offset until the PPS signal is available again, and then use the INSClkDrfit calculated in step 102 to correct the time offset. Figure 1 The method shown can be used to update INSClkDrfit.

[0072] In an exemplary embodiment, the method for implementing time synchronization in an integrated navigation system provided in an embodiment of the present application, after synchronizing INS time and GNSS time to obtain INS time and GNSS time in the same time coordinate system, may further include:

[0073] Time error compensation is performed on the INS velocity information and INS position information; combined navigation processing is performed using the time error-compensated INS velocity information and INS position information. This reduces the problem of system status information mismatch caused by time asynchrony.

[0074] In an exemplary embodiment, the time error compensation of the INS velocity information can be performed according to formula (6):

[0075] V INS' =V INS +a n ΔT (6)

[0076] In formula (6), V INS Indicates the INS velocity information without time error compensation; V INS' Indicates the INS speed information after time error compensation; ΔT = GNSS.Time - INS.Time, which indicates the difference between GNSS time and INS time; a n represents the average linear acceleration of the carrier near the non-synchronous time. In one embodiment, a n INS can be used to detect the presence of a signal at two adjacent times (e.g. T = t m -t m-1 ) is approximated by the average velocity change within

[0077] In an exemplary embodiment, the time error compensation of the INS position information can be performed according to formula (7):

[0078] P INS' =P INS +M pv V INS ΔT (7)

[0079] In formula (7), P INS Indicates the INS position information without time error compensation, P INS' Indicates the INS position information after time error compensation;

[0080] In formula (7), Among them, L, λ, and h represent latitude, longitude, and altitude respectively, and R M Indicates the principal radius of curvature of the meridian, R N represents the principal curvature radius of the ellipsoid, h represents the height of the ellipsoid at the location, and f represents the flattening of the ellipsoid.

[0081] The method for achieving time synchronization in an integrated navigation system provided in an embodiment of the present application, after achieving synchronization of INS time and GNSS time to obtain INS time and GNSS time in the same time coordinate system, further performs time error compensation on INS velocity information and INS position information, and uses the time error-compensated INS velocity information and INS position information to perform integrated navigation processing. In this way, the problem of system status information mismatch caused by time asynchrony is reduced.

[0082] The present application also provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute any of the above methods for implementing time synchronization in a combined navigation system.

[0083] The present application further provides a device for implementing time synchronization of an integrated navigation system, comprising a memory and a processor, wherein the memory stores the following instructions executable by the processor: for executing the steps of any of the above-mentioned methods for implementing time synchronization of an integrated navigation system.

[0084] Figure 3 FIG. 1 is a schematic diagram of a structure of a device for realizing time synchronization in a combined navigation system according to an embodiment of the present application. Figure 3 As shown, it includes: an acquisition module, a processing module, and a synchronization module; wherein,

[0085] an acquisition module, configured to acquire local PPS time and time quality upon arrival of a first PPS signal; acquire INS data and INS time after the first PPS signal and before the arrival of a second PPS signal, when INS data is ready; store the acquired local PPS time, time quality, and INS time in a time synchronization data set; acquire local PPS time and time quality upon arrival of a second PPS signal; acquire INS data and INS time after the second PPS signal and before the arrival of a third PPS signal, when INS data is ready; store the acquired local PPS time, time quality, and INS time in the time synchronization data set;

[0086] a processing module configured to calculate, for arrays with the same time quality in the time synchronization data set, a phase offset of the INS time based on the local PPS time and the INS time in the array; and, for arrays with precise time quality in the time synchronization data set, calculate a time difference between the INS time at which the second PPS signal arrives and the INS time in the array with precise time quality;

[0087] The synchronization module is used to synchronize the time of the INS data at the arrival moment of the second PPS signal according to the calculated phase offset and time difference.

[0088] In an exemplary embodiment, the apparatus for implementing time synchronization in an integrated navigation system provided in an embodiment of the present application may further include a preprocessing module configured to:

[0089] The clock is synchronized with the GNSS satellite system clock and calibrated. The PPS signal is output at precise intervals based on the calibrated clock of the GNSS receiver to which the preprocessing module belongs. The time accuracy of the PPS signal is maintained by the receiver itself.

[0090] In an exemplary embodiment, before the third PPS signal arrives, each time INS data is ready, the processing module uses the calculated phase offset as the INS time offset to perform time synchronization calibration.

[0091] In an exemplary embodiment, if the subsequent PPS signal is unavailable, the processing module uses the calculated phase offset to correct the time offset until the PPS signal is available again, and then updates the phase offset again.

[0092] The device for implementing time synchronization of the integrated navigation system provided in the embodiment of the present application enables high time synchronization accuracy and good real-time performance of the GNSS and INS integrated navigation systems, eliminates errors caused by time asynchrony when fusing different data sources, and thereby improves the optimal estimation of state quantities such as attitude, velocity, and position of the integrated navigation system.

[0093] In an exemplary embodiment, the apparatus for implementing time synchronization in an integrated navigation system provided in an embodiment of the present application may further include a compensation module for:

[0094] After synchronizing INS and GNSS time to obtain the same time coordinate system, time error compensation is performed on the INS velocity and position information. Combined navigation processing is then performed using the time-error-compensated INS velocity and position information. This reduces the problem of system status information mismatch caused by time asynchrony.

[0095] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application. However, the scope of patent protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. A method for achieving time synchronization of an integrated navigation system, characterized in that: include: When the first pulse per second (PPS) signal arrives, the local PPS time and time quality are obtained; when the inertial navigation system (INS) data is ready after the first PPS signal and before the second PPS signal arrives, the INS data and INS time are obtained; the obtained local PPS time, time quality, and INS time are stored in the time synchronization data set; When the second PPS signal arrives, obtain the local PPS time and time quality. After the second PPS signal and before the third PPS signal arrives, when the INS data is ready, obtain the INS data and INS time. Store the obtained local PPS time, time quality, and INS time in the time synchronization data set. For arrays with the same time quality in the time synchronization data set, the phase offset of the INS time is calculated based on the local PPS time and INS time in the array; for arrays with accurate time quality in the time synchronization data set, the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality is calculated; The time of the INS data at the moment when the second PPS signal arrives is synchronized according to the calculated phase offset and time difference.

2. The method according to claim 1, further comprising: The satellite navigation system GNSS receiver synchronizes with the GNSS satellite system clock to calibrate the clock; The GNSS receiver outputs the PPS signal at precise time intervals based on its own calibrated clock.

3. The method according to claim 1, wherein The time of the INS data at the arrival time of the second PPS signal is synchronized according to the following formula: INS.Time=INS_PPSTimeSyncInfo[j].PPStime+dt*(1+INSClkDrfit); Among them, the synchronized INS.Time represents the time of the INS data at the moment the second PPS signal arrives; INS_PPSTimeSyncInfo[j].PPSTime represents the PPS time in the first array with the time quality TimeQuality of Accurate; dt represents the time difference between the INS time when the second PPS signal arrives and the INS time in the array with the time quality of Accurate; INSClkDrift represents the phase offset of the INS time.

4. The method according to any one of claims 1 to 3, wherein: Calculating the phase offset of the INS time according to the local PPS time and the INS time in the array includes: Starting from the array at the end of the storage of the time synchronization data set, the time quality in the array is compared with the time quality in the array when the current INS data is ready. If the time quality is the same, the array number i is recorded and the phase offset of the INS time is calculated according to the following formula: Among them, the calculations of dt_PPS and dt_INS are as follows: dt_PPS=INS_PPSTimeSyncInfo[0].PPSTime-INS_PPSTimeSyncInfo[i].PPSTime; dt_INS=INS_PPSTimeSyncInfo[0].INSTime-INS_PPSTimeSyncInfo[i].INSTime; Wherein, i is an integer greater than or equal to 1; dt_PPS represents the difference between the PPS time INS_PPSTimeSyncInfo[0].PPSTime in the array when the current INS data is ready and the PPS time INS_PPSTimeSyncInfo[i].PPSTime in the array i with the same time quality as the current INS data is ready; dt_INS represents the difference between the INS time INS_PPSTimeSyncInfo[0].INSTime in the array when the current INS data is ready and the INS time INS_PPSTimeSyncInfo[i].INSTime in the array i with the same time quality as the current INS data is ready.

5. The method according to any one of claims 1 to 3, wherein: The calculating the time difference between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality includes: From the arrays in the time synchronization data set except the array when the current INS data is ready, search for an array including an array with accurate time quality, and calculate the time difference dt between the INS time when the second PPS signal arrives and the INS time in the array with accurate time quality.

6. The method according to claim 1 or 2, further comprising: Before the third PPS signal arrives, each time the INS data is ready, the phase offset is used as an INS time offset to synchronize the time of the INS data.

7. The method according to claim 1 or 2, further comprising: The INS uses the phase offset to correct the time offset until the PPS signal is available again, and then returns to the step of obtaining the local PPS time and time quality to update the phase offset.

8. The method according to claim 1 or 2, further comprising: after synchronizing the time of the second PPS signal arrival time INS data; Compensate the time error of INS velocity information and INS position information; The INS velocity information and INS position information after time error compensation are used for integrated navigation processing.

9. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method for implementing time synchronization of an integrated navigation system according to any one of claims 1 to 8.

10. A device for implementing time synchronization in an integrated navigation system, comprising a memory and a processor, wherein: The memory stores the following instructions that can be executed by the processor: instructions for executing the steps of the method for implementing time synchronization of the integrated navigation system according to any one of claims 1 to 8.

11. A device for achieving time synchronization of an integrated navigation system, characterized in that: include: Acquisition module, processing module, and synchronization module; among them, An acquisition module is configured to acquire local PPS time and time quality when a first PPS signal arrives; acquire INS data and INS time when INS data is ready after the first PPS signal and before the second PPS signal arrives; and store the acquired local PPS time, time quality, and INS time in a time synchronization data set; When the second PPS signal arrives, obtain the local PPS time and time quality. After the second PPS signal and before the third PPS signal arrives, when the INS data is ready, obtain INS data and INS time. Store the obtained local PPS time, time quality, and INS time in the time synchronization data set. a processing module configured to calculate, for arrays with the same time quality in the time synchronization data set, a phase offset of the INS time based on the local PPS time and the INS time in the array; and, for arrays with precise time quality in the time synchronization data set, calculate a time difference between the INS time at which the second PPS signal arrives and the INS time in the array with precise time quality; The synchronization module is used to synchronize the time of the INS data at the arrival moment of the second PPS signal according to the calculated phase offset and time difference.

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