Variable Dual-Vector Attitude Control Method for Satellites in Highly Elliptical Orbits

Abstract

The present invention discloses a variable dual-vector attitude control method for a large elliptical orbit satellite. The method comprises: determining a satellite orbit mission and segmenting the satellite orbit according to different satellite orbit missions to obtain satellite orbit segments for different missions; constructing a reference coordinate system corresponding to each mission satellite orbit segment and a satellite body attitude coordinate system; and tracking the reference coordinate system corresponding to each mission satellite orbit segment via the satellite body attitude coordinate system to perform satellite attitude control. The present invention can plan satellite attitude based on the mission characteristics of satellites at different altitude segments of a large elliptical orbit, lighting conditions, and satellite angular momentum.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite attitude control, and in particular to a variable dual-vector attitude control method for a large elliptical orbit satellite. Background Art

[0002] Satellites in highly elliptical orbits have an eccentricity much greater than 0.1, resulting in slower angular motion at apogee, allowing for longer dwell times and facilitating observation of ground targets. Scientists have recently developed a lightning orbit, an example of this type of orbit, designed for long-term observations at high latitudes and used for communications, meteorology, and other purposes. However, due to the complex relationship between the satellite's orbit and the sun, conventional attitude control of satellites in highly elliptical orbits over the satellite's lifetime would make it difficult to implement onboard sensor layout and heat dissipation surfaces if conventional attitude control was used. Therefore, new measures are needed to address attitude control for satellites in highly elliptical orbits. Summary of the Invention

[0003] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide a variable dual-vector attitude control method for a highly elliptical orbit satellite, thereby enabling satellite attitude planning based on the mission characteristics, illumination conditions, and angular momentum of the satellite at different altitudes in the highly elliptical orbit.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A variable dual-vector attitude control method for a highly elliptical orbit satellite, comprising:

[0006] Determining satellite orbit operation missions, and segmenting the satellite orbit according to different satellite orbit operation missions to obtain satellite orbit segments for different missions;

[0007] Construct the reference coordinate system corresponding to the satellite orbit segment of each mission, and construct the satellite body attitude coordinate system;

[0008] The reference coordinate system corresponding to the satellite orbit segment of each mission is tracked through the satellite body attitude coordinate system to perform satellite attitude control.

[0009] Optionally, the step of constructing a reference coordinate system corresponding to the satellite orbit segment includes:

[0010] Determining a target to which the satellite attitude is pointing in the satellite orbit segment;

[0011] Determine the position vectors of the satellite and the target respectively, and determine the Z-axis vector of the reference coordinate system according to the satellite position vector and the target position vector;

[0012] Determine a sun vector of the satellite pointing to the sun, and determine a Y-axis vector of the reference coordinate system based on the Z-axis vector of the reference coordinate system and the sun vector;

[0013] The reference coordinate system corresponding to the satellite orbit segment is determined according to the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system.

[0014] Optionally, the satellite orbit segment includes a high-orbit mission segment, a medium-orbit mission segment and a low-orbit mission segment.

[0015] Optionally, the steps of constructing the satellite body attitude coordinate system include:

[0016] Determine the satellite payload pointing as the Zb axis vector of the satellite body attitude coordinate system, and determine the direction vector in the fixed sunlit surface perpendicular to the satellite payload pointing as the Xb axis vector of the satellite body attitude coordinate system;

[0017] The satellite body attitude coordinate system is determined according to the Zb axis vector of the satellite body attitude coordinate system and the Xb axis vector of the satellite body attitude coordinate system.

[0018] Optionally, the method further includes:

[0019] A satellite operation avoidance zone is determined, and when a satellite operates into the satellite operation avoidance zone, the satellite is controlled to enter an avoidance mode.

[0020] Optionally, the satellite altitude interval corresponding to when the angle between the sun vector and the vector pointing to the target by the satellite is determined to be less than a first preset value or greater than a second preset value is the satellite operation avoidance zone.

[0021] Optionally, in the avoidance mode, a virtual target avoidance method is adopted, or the orbital coordinate system is used as the reference coordinate system to control the satellite attitude.

[0022] Optionally, the virtual target avoidance method specifically includes:

[0023] A virtual target point is constructed so that the angle between the sun vector and the vector pointing to the virtual target point by the satellite is between the first preset value and the second preset value, and the reference coordinate system is reconstructed by constructing the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system. The satellite attitude is controlled with the reconstructed reference coordinate system as the control target, so as to adjust the direction of the satellite body attitude coordinate system.

[0024] Optionally, the step of constructing the orbital coordinate system includes:

[0025] The direction vector pointing to the center of the earth is used as the Z-axis vector of the orbital coordinate system, and the direction vector pointing to the negative normal of the orbital plane is used as the Y-axis vector of the orbital coordinate system;

[0026] The orbital coordinate system is constructed according to the Z-axis vector of the orbital coordinate system and the Y-axis vector of the orbital coordinate system.

[0027] Optionally, the method further includes: when the satellite moves to the low-orbit mission segment, using the geomagnetic field to unload and manage the satellite's angular momentum.

[0028] The present invention has at least the following technical effects:

[0029] The satellite attitude control method implemented by the present invention, which tracks the reference coordinate systems corresponding to each satellite orbital segment using a constructed satellite attitude coordinate system, can meet the mission requirements of satellites at different orbital altitudes, provide satellites with fixed heat dissipation surfaces, and facilitate the layout of star sensors. Furthermore, the method ensures the satellite's energy supply using only a one-dimensional solar array drive, and can manage the satellite's angular momentum. Furthermore, the present invention uses a virtual target avoidance method and uses the orbital coordinate system as a reference coordinate system to control the satellite's entry into an avoidance zone.

[0030] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a variable dual-vector attitude control method for a highly elliptical orbit satellite provided by one embodiment of the present invention;

[0032] Figure 2 A track segmentation diagram of different track height segments provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present embodiment is described in detail below. Examples of the embodiment are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0034] The variable dual-vector attitude control method for a large elliptical orbit satellite according to this embodiment will be described below with reference to the accompanying drawings.

[0035] Figure 1 This is a flow chart of a variable dual-vector attitude control method for a large elliptical orbit satellite provided by one embodiment of the present invention. Figure 1 As shown, the method includes:

[0036] Step S1: Determine the satellite orbit operation mission, and segment the satellite orbit according to different satellite orbit operation missions to obtain satellite orbit segments for different missions.

[0037] Specifically, the satellite orbit operation mission may include a high orbit operation mission, a medium orbit operation mission and a low orbit operation mission. In this embodiment, the satellite orbit can be segmented according to these orbit operation missions to obtain satellite orbit segments of different missions, such as Figure 2 As shown, for example, it includes a high-orbit mission segment, a medium-orbit mission segment, and a low-orbit mission segment.

[0038] Step S2: Construct the reference coordinate system corresponding to each satellite orbit segment and construct the satellite body attitude coordinate system.

[0039] Among them, the steps of constructing a reference coordinate system corresponding to the satellite orbit segment include: determining the target to which the satellite attitude points under the satellite orbit segment; determining the position vectors of the satellite and the target respectively, and determining the Z-axis vector of the reference coordinate system based on the satellite position vector and the target position vector; determining the sun vector of the satellite pointing to the sun, and determining the Y-axis vector of the reference coordinate system based on the Z-axis vector of the reference coordinate system and the sun vector; and determining the reference coordinate system corresponding to the satellite orbit segment based on the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system.

[0040] Specifically, after segmenting the orbit according to mission requirements, the target point that the satellite is pointing to in each segment can be determined. The vector pointing from the satellite to the target point is then used as the Z-axis vector of the reference coordinate system, and the sun vector Vect is used as another tracking vector. The unit vector formed by the cross product of the Z-axis vector and the sun vector Vect is used as the reference Y-axis. Since the X-axis is perpendicular to the Y and Z axes, a reference coordinate system can be constructed based on this.

[0041] As an example, we can define the target point's position vector as R_target, the satellite's current position vector as R_now, and the satellite's unit vector pointing to the sun, i.e., the sun vector, as Vect. Furthermore, we can obtain the reference coordinate system's Z-axis vector as:

[0042]

[0043] The Y-axis vector of the reference coordinate system is:

[0044]

[0045] Since X=Y×Z, the reference coordinate system can be obtained accordingly, and the dual-vector reference attitude reference attitude conversion matrix A_out can be calculated from it:

[0046] A_out=[XYZ] T (3)

[0047] In one embodiment of the present invention, the step of constructing a satellite body attitude coordinate system includes: determining the direction of the satellite payload as the Zb-axis vector of the satellite body attitude coordinate system, and determining the direction vector in the fixed sunlit surface perpendicular to the direction of the satellite payload as the Xb-axis vector of the satellite body attitude coordinate system; determining the satellite body attitude coordinate system based on the Zb-axis vector of the satellite body attitude coordinate system and the Xb-axis vector of the satellite body attitude coordinate system.

[0048] Specifically, the satellite can select the payload pointing direction as the Zb axis of the satellite body attitude coordinate system, define a fixed sunlit surface perpendicular to the payload pointing as the +Xb surface, and define a direction in the fixed sunlit surface as the Xb axis of the satellite body attitude coordinate system. Since the Yb axis is perpendicular to the Zb and Xb axes, the satellite body attitude coordinate system can be constructed based on this.

[0049] Step S3: Track the reference coordinate system corresponding to each satellite orbit segment through the satellite body attitude coordinate system to control the satellite operation.

[0050] In one embodiment of the present invention, the method further includes: determining a satellite operation avoidance zone, and controlling the satellite to enter an avoidance mode when the satellite operates into the satellite operation avoidance zone.

[0051] Among them, it can be determined that the satellite altitude interval corresponding to when the angle between the sun vector and the vector pointing to the target by the satellite is less than a first preset value or greater than a second preset value is the satellite operation avoidance zone.

[0052] Specifically, the satellite altitude interval where the angle between the sun vector and the satellite's target-pointing vector is less than a first preset value (e.g., 20°) or greater than a second preset value (e.g., 160°) can be determined as a satellite operation avoidance zone. For example, when the condition |Z×Vect|≤sin(20°) is satisfied between the target vector Z (i.e., the satellite's target-pointing vector) and the sun vector Vect, the satellite can be determined to have entered the satellite operation avoidance zone at the corresponding time point. Furthermore, within this interval, the satellite can autonomously control itself to enter avoidance mode.

[0053] In this embodiment, in the avoidance mode, a virtual target avoidance method or a method of using the orbital coordinate system as a reference coordinate system may be used to control the satellite attitude.

[0054] Among them, the virtual target avoidance method specifically includes: constructing a virtual target point so that the angle between the sun vector and the vector pointing to the virtual target point by the satellite is between a first preset value and a second preset value, and reconstructing the reference coordinate system by constructing the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system, and controlling the satellite attitude with the reconstructed reference coordinate system as the control target, so as to adjust the direction of the satellite body attitude coordinate system.

[0055] Specifically, a virtual target point can be constructed so that the angle between the vector pointing to the virtual target point and the sun vector is, for example, between 20° and 160°. Then, the reference coordinate system construction method mentioned above is used to reconstruct the reference coordinate system of the avoidance zone, and the reconstructed reference coordinate system is used as the control target to control the satellite attitude and thereby adjust the direction of the satellite body attitude coordinate system.

[0056] In one embodiment of the present invention, the steps of constructing the orbital coordinate system include: using a direction vector pointing towards the center of the earth as the Z-axis vector of the orbital coordinate system, and using a direction vector pointing towards the negative normal of the orbital surface as the Y-axis vector of the orbital coordinate system; and constructing the orbital coordinate system based on the Z-axis vector and the Y-axis vector of the orbital coordinate system.

[0057] For example, the Zo axis can be specified to point to the center of the earth, the Yo axis can point to the negative normal of the orbital plane, and the Xo axis can be perpendicular to the Yo and Zo axes. In this way, an orbital coordinate system can be established and used as a reference coordinate system.

[0058] In one embodiment of the present invention, the method further includes: when the satellite moves to the low-orbit mission phase, using the geomagnetic field to manage the unloading of the satellite's angular momentum.

[0059] Specifically, a satellite orbit altitude of 12,000 km can be selected as the threshold for determining low-orbit operation. When the satellite's operating altitude is lower than 12,000 km, the satellite is considered to be operating at a low altitude. When the satellite's orbit altitude is low, the geomagnetic field can be used to unload the satellite's angular momentum, thereby achieving satellite angular momentum management.

[0060] In summary, the satellite attitude control method implemented by the present invention, which tracks the reference coordinate systems corresponding to each satellite orbital segment using a constructed satellite attitude coordinate system, can meet the mission requirements of satellites at different orbital altitudes, provide satellites with fixed heat dissipation surfaces, and facilitate the layout of star sensors. Furthermore, this method, driven solely by a one-dimensional solar array, can ensure the satellite's energy supply and manage the satellite's angular momentum. Furthermore, the present invention, through virtual target avoidance and the use of the orbital coordinate system as a reference coordinate system, can control the satellite's entry into an avoidance zone.

[0061] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0062] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A variable dual-vector attitude control method for a highly elliptical orbit satellite, characterized in that: include: Determining satellite orbit operation missions, and segmenting the satellite orbit according to different satellite orbit operation missions to obtain satellite orbit segments for different missions; Construct the reference coordinate system corresponding to the satellite orbit segments of different missions, and construct the satellite body attitude coordinate system; The reference coordinate system corresponding to the satellite orbit segments of different missions is tracked through the satellite body attitude coordinate system to perform satellite attitude control.

2. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 1, wherein: The steps of constructing a reference coordinate system corresponding to the satellite orbit segment include: Determining a target to which the satellite attitude is pointing in the satellite orbit segment; Determine the satellite position vector and the target position vector respectively, and determine the Z-axis vector of the reference coordinate system according to the satellite position vector and the target position vector; Determine a sun vector of the satellite pointing to the sun, and determine a Y-axis vector of the reference coordinate system based on the Z-axis vector of the reference coordinate system and the sun vector; The reference coordinate system corresponding to the satellite orbit segment is determined according to the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system.

3. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 1, wherein: The satellite orbit segment includes a high orbit mission segment, a medium orbit mission segment and a low orbit mission segment.

4. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 1, wherein: The steps to construct the satellite body attitude coordinate system include: Determine the satellite payload pointing as the Zb axis vector of the satellite body attitude coordinate system, and determine the direction vector in the fixed sunlit surface perpendicular to the satellite payload pointing as the Xb axis vector of the satellite body attitude coordinate system; The satellite body attitude coordinate system is determined according to the Zb axis vector of the satellite body attitude coordinate system and the Xb axis vector of the satellite body attitude coordinate system.

5. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 2, wherein: The method further comprises: A satellite operation avoidance zone is determined, and when a satellite operates into the satellite operation avoidance zone, the satellite is controlled to enter an avoidance mode.

6. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 5, characterized in that: Determine that the satellite altitude interval corresponding to when the angle between the sun vector and the vector pointing to the target by the satellite is less than a first preset value or greater than a second preset value is the satellite operation avoidance zone.

7. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 6, characterized in that: In the avoidance mode, the satellite attitude is controlled by using a virtual target avoidance method or a method of using the orbital coordinate system as the reference coordinate system.

8. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 7, characterized in that: The virtual target avoidance method specifically includes: A virtual target point is constructed so that the angle between the sun vector and the vector pointing to the virtual target point by the satellite is between the first preset value and the second preset value, and the reference coordinate system is reconstructed by constructing the Z-axis vector of the reference coordinate system and the Y-axis vector of the reference coordinate system. The satellite attitude is controlled with the reconstructed reference coordinate system as the control target, so as to adjust the direction of the satellite body attitude coordinate system.

9. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 7, wherein: The steps of constructing the orbital coordinate system include: The direction vector pointing to the center of the earth is used as the Z-axis vector of the orbital coordinate system, and the direction vector pointing to the negative normal of the orbital plane is used as the Y-axis vector of the orbital coordinate system; The orbital coordinate system is constructed according to the Z-axis vector of the orbital coordinate system and the Y-axis vector of the orbital coordinate system.

10. The variable dual-vector attitude control method for a large elliptical orbit satellite according to claim 3, characterized in that: The method further includes: when the satellite moves to the low-orbit mission segment, using the geomagnetic field to unload and manage the satellite's angular momentum.

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