Method for satellite terminal to search satellites and determine course angle when course angle is uncertain

Abstract

The invention provides a method for a satellite terminal to search satellites and determine a course angle when the course angle is uncertain, and relates to the field of satellite communication, and the method comprises the steps: determining a preliminary course angle Yrpt, a roll angle Rrpt, a pitch angle Prpt and a rotation matrix R of the terminal; the traversal sequence of the ENU azimuth angles AZIenu of the antennas is determined according to the mode that the ENU azimuth angles AZIenu of the antennas are parallel from left to right; traversing X kilometers around the satellite position, calculating the maximum and minimum ENU elevation angles of an antenna within the range of positive and negative X kilometers, combining the ENU azimuth angle AZIenu, the minimum ENU elevation angle and the maximum ENU elevation angle as the angle of an ENU coordinate system, obtaining the angle of a carrier coordinate system through the transformation of a rotation matrix R, configuring satellite searching according to the angle of the carrier coordinate system, and if the satellite searching is not successful, updating the ENU azimuth angle AZIenu and repeating the step; and the real course angle of the terminal is calculated based on the ENU azimuth AZIenu when satellite searching succeeds. The technical problem that satellite searching cannot be carried out when the course angle is uncertain can be solved, and the course angle can be determined in the satellite searching process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite communication, in particular to a method for searching for a satellite and determining a heading angle when the heading angle is uncertain. BACKGROUND

[0002] In a satellite communication system, a dual-GPS or a superimposed geomagnetic sensor is usually required for a heading angle determination by an inertial navigation module. However, some inertial navigation modules do not have a dual-GPS or a geomagnetic sensor, and a dual-GPS can be simulated by a rotation mode to determine the heading angle. However, some terminals have a relatively fixed position and are inconvenient to rotate at will.

[0003] The satellite searching scheme when the heading angle is determined is as follows: The terminal determines a satellite position according to an almanac, determines a self position according to a GPS, and points an antenna to the satellite position, thereby obtaining a pointing vector Senu in an ENU coordinate system (composed of an azimuth angle AZIenu and an elevation angle ELEenu). The pointing vector Senu is converted into Sbody (composed of an azimuth angle AZIbody and an elevation angle ELEbody) through a rotation matrix (composed of a roll angle, a pitch angle, and a heading angle reported by the inertial navigation module), and the process is referred to as an inertial navigation fusion. The Sbody after the fusion is the antenna pointing based on the carrier coordinate system. Since the almanac has a low accuracy, the satellite position is required to be searched within a range of X kilometers around the satellite position to configure the antenna pointing multiple times to ensure the success of the satellite searching.

[0004] When the heading angle is uncertain, the rotation matrix is inaccurate, which causes the Sbody to be incorrect, and the antenna pointing is finally incorrect, and the satellite searching cannot be completed. SUMMARY

[0005] Embodiments of the present application provide a method for searching for a satellite and determining a heading angle when the heading angle is uncertain, to determine the heading angle through a satellite searching process when the heading angle is uncertain.

[0006] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0007] According to a first aspect of the embodiments of the present application, a method for searching for a satellite and determining a heading angle when the heading angle is uncertain is provided, comprising: Step S100: determining a terminal preliminary heading angle Yrpt, a roll angle Rrpt, a pitch angle Prpt, and a rotation matrix R composed of the terminal preliminary heading angle Yrpt, the roll angle Rrpt, and the pitch angle Prpt by a terminal inertial navigation according to a terminal self position and attitude; Step S200: Determine the traversal order of the antenna's ENU azimuth angle AZIenu in parallel from left to right. Step S300: Traverse the area around the satellite position within X kilometers, calculate the maximum and minimum ENU elevation angles of the antenna within a range of ±X kilometers, combine the ENU azimuth angle AZIenu, the minimum ENU elevation angle, and the maximum ENU elevation angle as the angle of the ENU coordinate system, and then obtain the angle of the carrier coordinate system through the rotation matrix R. Configure the satellite search according to the angle of the carrier coordinate system. If the satellite search is successful, jump to step S400. If it is unsuccessful, update the ENU azimuth angle AZIenu and repeat step S300, where X is a positive integer. Step S400: Calculate the terminal's true heading angle based on the ENU azimuth angle AZIenu when the satellite search is successful.

[0008] In some embodiments of this application, the satellite position is determined according to an almanac based on the aforementioned scheme.

[0009] In some embodiments of this application, based on the aforementioned scheme, in step S100, the location of the satellite terminal itself is determined according to GPS.

[0010] In some embodiments of this application, based on the foregoing scheme, the traversal order of the ENU azimuth angle AZIenu in step S200 refers to: 0 1 degree 359 degrees 2 degrees 358 degrees 3 degrees 357 degrees …180 degrees.

[0011] In some embodiments of this application, based on the aforementioned scheme, in step S300, during the satellite search process, the initial value of the ENU azimuth angle AZIenu is set to 0. When the satellite search fails and the ENU azimuth angle AZIenu needs to be updated, the ENU azimuth angle AZIenu is updated according to the traversal order.

[0012] In some embodiments of this application, based on the foregoing scheme, step S400 specifically includes: The ENU azimuth angle AZIenu at the time of successful satellite acquisition is denoted as AZIenu_succ; Calculate the azimuth angle AZIenu_curr in the ENU coordinate system at this time based on the searched ephemeris; Based on the ENU azimuth angle AZIenu_succ, the ENU coordinate system azimuth angle AZIenu_curr, and the terminal's initial heading angle Yrpt, the terminal's true heading angle Ytrue is determined using the following formula: Ytrue = AZIenu_curr - AZIenu_succ + Yrpt.

[0013] The technical solution of this application can solve the technical problem that satellite search cannot be performed when the heading angle is uncertain, and the heading angle can be determined during the satellite search process.

[0014] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 A flowchart illustrating a method for a satellite terminal to search for and determine a course angle when the course angle is uncertain, according to an embodiment of this application, is shown. Figure 2 A schematic diagram of a process for traversing azimuth angles according to an embodiment of this application is shown. Detailed Implementation

[0016] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0017] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0018] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] The following detailed description of some embodiments of this application will be provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] See Figure 1 The diagram illustrates a process flow diagram of a method for a satellite terminal to search for and determine a course angle when the course angle is uncertain, according to an embodiment of this application.

[0022] like Figure 1 As shown, a method for a satellite terminal to search for and determine the heading angle when the heading angle is uncertain is illustrated, specifically including steps S100 to S400.

[0023] It should be noted that this method is based on the equivalence of antenna azimuth angle and inertial navigation direction angle transformation. The derivation of the equivalence of antenna azimuth angle and inertial navigation direction angle transformation is as follows: Elevation angle of the load system Carrier azimuth Elevation angle in ENU coordinate system Azimuth of ENU coordinate system ; Based on the inertial navigation fusion process and the azimuth and elevation angle calculation process, we can obtain:

[0024] Therefore, we can conclude that changing the inertial navigation heading angle And change the azimuth angle of the antenna ENU system equivalence.

[0025] refer to Figure 1 In step S100, the terminal inertial navigation system determines the terminal's initial heading angle Yrpt, roll angle Rrpt, pitch angle Prpt, and rotation matrix R composed of the terminal's initial heading angle Yrpt, roll angle Rrpt, and pitch angle Prpt based on the terminal's own position and attitude.

[0026] It should be noted that the rotation matrix R is used for inertial navigation fusion in subsequent processes.

[0027] It should be noted that the inertial navigation heading angle is currently uncertain, and it can be reported directly as 0 or a fixed value.

[0028] The inertial navigation fusion process is as follows: , , The inertial navigation system (INS) provides the three-axis attitude angles. The INS fusion formula can be used to transform the ENU coordinates to the carrier coordinates. .

[0029] In some feasible embodiments, the satellite position is determined according to an almanac based on the aforementioned scheme.

[0030] In some feasible embodiments, based on the aforementioned scheme, in step S100, the location of the satellite terminal itself is determined according to GPS.

[0031] Continue to refer to Figure 1 In step S200, the traversal order of the antenna's ENU azimuth angle AZIenu is determined in parallel from left to right.

[0032] In some feasible embodiments, based on the foregoing scheme, the traversal order of the ENU azimuth angle AZIenu in step S200 refers to: 0 1 degree 359 degrees 2 degrees 358 degrees 3 degrees 357 degrees …180 degrees.

[0033] It should be noted that the reason for traversing in this order is as follows: During the satellite search process, the satellite is constantly moving. If the search continues in only one direction, it may lead to search failure. See the appendix for details. Figure 2 .

[0034] Continue to refer to Figure 1 In step S300, traverse the area around the satellite position within X kilometers and calculate the maximum and minimum ENU elevation angles of the antenna within a range of ±X kilometers. Combine the ENU azimuth angle AZIenu, the minimum ENU elevation angle, and the maximum ENU elevation angle as the angle of the ENU coordinate system. Then, transform the angle of the carrier coordinate system using the rotation matrix R. Configure the satellite search according to the angle of the carrier coordinate system. If the satellite search is successful, proceed to step S400. If it is unsuccessful, update the ENU azimuth angle AZIenu and repeat step S300. Here, X is a positive integer.

[0035] It should be noted that in this embodiment, the value of X is determined based on the actual situation.

[0036] In some feasible embodiments, based on the aforementioned scheme, in step S300, during the satellite search process, the initial value of the ENU azimuth angle AZIenu is set to 0. When the satellite search fails and the ENU azimuth angle AZIenu needs to be updated, the ENU azimuth angle AZIenu is updated according to the traversal order.

[0037] It should be noted that, in this embodiment, updating the ENU azimuth angle AZIenu according to the traversal order specifically means: according to 0 1 degree 359 degrees 2 degrees 358 degrees 3 degrees 357 degrees …180-degree update of ENU azimuth angle AZIenu.

[0038] Continue to refer to Figure 1 Step S400: Calculate the terminal's true heading angle based on the ENU azimuth angle AZIenu when the satellite search is successful.

[0039] In some feasible embodiments, based on the foregoing scheme, step S400 specifically includes: The ENU azimuth angle AZIenu at the time of successful satellite acquisition is denoted as AZIenu_succ; Calculate the azimuth angle AZIenu_curr in the ENU coordinate system at this time based on the searched ephemeris; Based on the ENU azimuth angle AZIenu_succ, the ENU coordinate system azimuth angle AZIenu_curr, and the terminal's initial heading angle Yrpt, the terminal's true heading angle Ytrue is determined using the following formula: Ytrue = AZIenu_curr - AZIenu_succ + Yrpt.

[0040] In summary, this method has the following advantages: 1. Traversing the 360-degree heading angle in a parallel left-right manner can ensure successful satellite acquisition for moving satellites. This parallel left-right method can also solve the problem of continuous changes in the azimuth angle of the antenna ENU caused by satellite movement.

[0041] See Figure 2 The process of traversing the azimuth angle: If the left and right parallel method is not used, but S is adopted... B0 B1 B2 …Bn M An …A2 A1 A0 In the S-mode, the satellite moves from S_S during this process. S_M When the antenna is pointing to angle M, the satellite is located at S_M. When the antenna is pointing to A0, the satellite is located at S_E. If the antenna is pointing in a fixed direction, the satellite will move and the satellite will still fail to be found even after traversing 360 degrees of azimuth angle.

[0042] This plan adopts S B0 A0 B1 A1 B2 A2…Bn An M's antenna azimuth traversal method can overcome satellite search failures caused by satellite movement.

[0043] 2. Once satellite acquisition is successful and the correct heading angle can be determined, this heading angle can be used to calibrate the initial values ​​of the inertial navigation system (INS). Subsequently, the INS can overlay the values ​​from sensors such as gyroscopes onto the valid initial values ​​to report the correct three-axis attitude in real time.

[0044] 3. The problem scenario involves an unknown initial heading angle for the inertial navigation system (INS). The most straightforward approach is to iterate through the INS heading angles. This solution uses the antenna azimuth angles in the Enu coordinate system. Mathematically, it has been proven that iterating through the Enu coordinate system antenna azimuth angles is equivalent to iterating through the INS heading angles. The advantage of iterating through the Enu coordinate system antenna azimuth angles is its ease and rationality in engineering implementation; only the Enu coordinate system azimuth angles need to be changed, and other processes and steps do not require modification.

[0045] 4. This scheme is applicable to both mobile and geostationary satellites, making it universally suitable. During operation, only the azimuth angle of the antenna's ENU coordinates needs to be traversed; it does not affect other processes or stages of the satellite search, making it very simple to implement in engineering.

[0046] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. It should be understood that this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for a satellite terminal to search for and determine the heading angle when the heading angle is uncertain, characterized in that, include: Step S100: Based on the terminal's own position and attitude, the terminal inertial navigation system determines the terminal's initial heading angle Yrpt, roll angle Rrpt, pitch angle Prpt, and rotation matrix R composed of the terminal's initial heading angle Yrpt, roll angle Rrpt, and pitch angle Prpt. Step S200: Determine the traversal order of the antenna's ENU azimuth angle AZIenu in parallel from left to right. Step S300: Traverse the area around the satellite position within X kilometers, calculate the maximum and minimum ENU elevation angles of the antenna within a range of ±X kilometers, combine the ENU azimuth angle AZIenu, the minimum ENU elevation angle, and the maximum ENU elevation angle as the angle of the ENU coordinate system, and then obtain the angle of the carrier coordinate system through the rotation matrix R. Configure the satellite search according to the angle of the carrier coordinate system. If the satellite search is successful, jump to step S400. If it is unsuccessful, update the ENU azimuth angle AZIenu and repeat step S300, where X is a positive integer. Step S400: Calculate the terminal's true heading angle based on the ENU azimuth angle AZIenu when the satellite search is successful.

2. The method according to claim 1, characterized in that, The satellite's location was determined according to the almanac.

3. The method according to claim 1, characterized in that, In step S100, the location of the satellite terminal is determined based on GPS.

4. The method according to claim 1, characterized in that, In step S200, the traversal order of the ENU azimuth angle AZIenu refers to: 0 1 degree 359 degrees 2 degrees 358 degrees 3 degrees 357 degrees …180 degrees.

5. The method according to claim 4, characterized in that, In step S300, during the satellite search process, the initial value of the ENU azimuth angle AZIenu is set to 0. When the satellite search fails and the ENU azimuth angle AZIenu needs to be updated, the ENU azimuth angle AZIenu is updated according to the traversal order.

6. The method according to claim 1, characterized in that, Step S400 specifically includes: The ENU azimuth angle AZIenu at the time of successful satellite acquisition is denoted as AZIenu_succ; Calculate the azimuth angle AZIenu_curr in the ENU coordinate system at this time based on the searched ephemeris; Based on the ENU azimuth angle AZIenu_succ, the ENU coordinate system azimuth angle AZIenu_curr, and the terminal's initial heading angle Yrpt, the terminal's true heading angle Ytrue is determined using the following formula: Ytrue = AZIenu_curr - AZIenu_succ + Yrpt.

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