A control method for satellite phase adjustment using SADA

Abstract

The application relates to a control method for satellite phase adjustment using SADA, which comprises the following steps: in the sunlit area, the SADA controls the sun azimuth angle to ensure that the sailboard is oriented to the sun in real time and meets the demand of energy balance on the satellite; the sun azimuth angle is the included angle between the projection of the sun vector on the XOZ plane of the satellite and the Z axis of the satellite; in the earth shadow area, the SADA of different satellites is locked to a fixed angle respectively to ensure that the air resistance difference borne by different satellites is maximum, so that the phase adjustment effect is achieved; when the phase adjustment time is required, the SADA is locked to the fixed angle to complete the phase adjustment at the expected time. When the satellite attitude is long-term three-axis stabilization on the earth, the method can make the SADA of the micro-satellite control realize the sun sailboard orientation to the sun, meet the energy balance on the satellite, and meet the demand of completing the inter-satellite phase adjustment in a period of time.

Description

Technical Field

[0001] This invention relates to the field of satellite attitude and orbit control technology, and in particular to a control method for satellite phase adjustment using SADA. Background Technology

[0002] The Solar Array Drive Assembly (SADA) is one of the key components of a satellite. Artificial satellites weighing less than 1000 kg are collectively referred to as "microsatellites." Microsatellites are a new generation of satellites with specific applications. They are primarily used for communication, Earth remote sensing, interplanetary exploration, scientific research, and technological experiments. Their characteristics include: high technological content, short development cycle (approximately one year), low development cost, and the ability to be further networked to form a distributed constellation of "virtual large satellites." Compared to previous large satellites, microsatellites have many advantages, such as light weight, small size, and low production costs due to mass production.

[0003] As the number of microsatellites produced in batches gradually increases, the demand for satellite orbital phase control also increases significantly. Current mass production of microsatellites requires propulsion fuel for phase adjustment, which is used for general satellite phase control. However, low-cost propulsion fuels generally suffer from drawbacks such as low on-orbit thrust, low efficiency, and susceptibility to leakage, which are detrimental to the mass production of microsatellites. Summary of the Invention

[0004] The present invention aims to solve the technical problems in the prior art by providing a control method for satellite phase adjustment using SADA.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A control method for satellite phase adjustment using SADA includes the following steps:

[0007] Step 1: In the sunlit area, the SADA control angle tracks the solar azimuth angle to ensure that the solar panels are oriented toward the sun in real time, meeting the energy balance requirements of the satellite; the solar azimuth angle is the angle between the projection of the solar vector on the XOZ plane of the satellite and the Z-axis of the satellite;

[0008] Step 2: In the shadow area, different satellites are locked to a fixed angle by SADA to ensure that the difference in air resistance experienced by different satellites is maximized, thereby achieving the effect of phase adjustment;

[0009] Step 3: When there is a requirement for phase adjustment time, SADA locks at a fixed angle to complete the phase adjustment within the expected time.

[0010] In the above technical solution, in step 1, when the solar azimuth angle is greater than the judgment threshold and less than the difference between 360 degrees and the judgment threshold, the satellite is determined to be in the sunshine area; when controlling SADA, the solar azimuth angle is used as the expected tracking angle of SADA.

[0011] In the above technical solution, step 2 specifically means: when the solar azimuth angle is greater than the difference between 360 degrees and the judgment threshold or less than the judgment threshold, the satellite is determined to be in the Earth's shadow area; when controlling SADA, the fixed angle is used as the expected holding angle of SADA.

[0012] In the above technical solution, in step 1 and / or step 2, the threshold for determining the solar azimuth angle is 67 degrees.

[0013] In the above technical solution, in step 1 and / or step 2, the phase adjustment time is reduced by increasing the threshold for determining the solar azimuth angle.

[0014] In the above technical solution, the threshold for determining the solar azimuth angle is 115 degrees.

[0015] In the above technical solution, in step 2, the fixed angle locked is 90 degrees or 180 degrees.

[0016] In the above technical solution, in step 3, the fixed angle locked is 90 degrees or 180 degrees.

[0017] The present invention has the following beneficial effects:

[0018] When the satellite attitude is stable on three axes relative to Earth for a long period of time, the control method of using SADA for satellite phase adjustment in this invention can enable microsatellites to control SADA to achieve solar panel orientation to the sun to meet the on-board energy balance, while also meeting the requirement to complete inter-satellite phase adjustment within a certain period of time.

[0019] When a satellite is in a sun-synchronous orbit and equipped with SADA, the control method of using SADA for satellite phase adjustment of the present invention can enable microsatellites to control the SADA angle in the sunlit area to achieve solar panel orientation to meet the on-board energy balance, while controlling the SADA to lock at different angles in the shadow area to adjust the windward area of ​​different satellites, thereby enabling satellites in the same orbit to complete inter-satellite phase adjustment within a period of time. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 A schematic diagram defining the SADA angle.

[0022] Figure 2 This is a schematic diagram of the satellite's maximum windward surface.

[0023] Figure 3 This is a schematic diagram of the satellite's minimum windward surface.

[0024] Figure 4 This is a schematic diagram of one day's telemetry data from the SADA perspective. Detailed Implementation

[0025] The inventive concept of this invention is as follows: This invention provides a method for low-cost microsatellites in sun-synchronous orbits that does not use propulsion but only utilizes a low-cost SADA system without conductive slip rings. By controlling the SADA to lock different angles, the windward area of ​​the satellite is adjusted, thereby ensuring that different satellites experience different air resistance, thus achieving phase adjustment between satellites.

[0026] The present invention will now be described in detail with reference to the accompanying drawings.

[0027] The control method for satellite phase adjustment using SADA of the present invention includes the following steps:

[0028] Step 1: In the sunlit area, the SADA control angle tracks the solar azimuth angle to ensure that the solar panels are oriented toward the sun in real time, meeting the energy balance requirements of the satellite; the solar azimuth angle is the angle between the projection of the solar vector on the XOZ plane of the satellite and the Z-axis of the satellite;

[0029] Step 2: In the shadow area, different satellites are locked to a fixed angle by SADA to ensure that the difference in air resistance experienced by different satellites is maximized, thereby achieving the effect of phase adjustment;

[0030] Step 3: When there is a requirement for phase adjustment time, SADA locks at a fixed angle to complete the phase adjustment within the expected time.

[0031] When the solar azimuth angle is greater than the threshold but less than the difference between 360 degrees and the threshold, the satellite is determined to be in the sunlit area; when controlling SADA, the solar azimuth angle is used as the desired tracking angle of SADA. When the solar azimuth angle is greater than the difference between 360 degrees and the threshold or less than the threshold, the satellite is determined to be in the shadow area; when controlling SADA, a fixed angle is used as the desired holding angle of SADA.

[0032] In steps 1 and 2, the threshold for determining the solar azimuth angle can be set to 67 degrees. Alternatively, the phase adjustment time can be reduced by increasing the threshold for determining the solar azimuth angle, for example, by increasing the threshold to 115 degrees.

[0033] In steps 2 and 3, the fixed angles locked are 90 degrees and 180 degrees, respectively.

[0034] The following is a detailed description of the control method for satellite phase adjustment using SADA according to the present invention.

[0035] 1. SADA is installed on the entire satellite (entire satellite ± Y-axis).

[0036] For remote sensing satellites in sun-synchronous orbits, the angle β between the solar vector and the satellite's orbital plane is generally a constant value. The solar array control (SADA) can be installed along the ±Y axis of the satellite. The satellite controls the SADA angle to track the solar azimuth angle, achieving solar orientation of the solar array. This installation method has a clear physical concept, simplifies pointing calculations, and reduces the complex rotation of the SADA.

[0037] 2. Definition of solar azimuth

[0038] The definition of solar azimuth is as follows: Figure 1 As shown, the angle between the projection of the solar vector onto the XOZ plane of the star and the Z-axis of the star is the solar azimuth angle. It is defined as 0° when it coincides with the Z-axis of the star. When the satellite is in a long-term three-axis orientation towards the Earth, as the satellite orbits the Earth once, the projection of the solar vector onto the XOZ plane of the star changes from 0 degrees to 360 degrees, that is, the solar azimuth angle changes from 0 degrees to 360 degrees. When observing the solar azimuth angle from the +Y side of the star, it is a counterclockwise rotation.

[0039] 3. Relationship between solar azimuth and satellite's shadow area

[0040] For satellites in sun-synchronous orbit, when the sun's azimuth angle is greater than 67 degrees and less than 293 degrees, the satellite is in the sunlit area; when the sun's azimuth angle is greater than 293 degrees or less than 67 degrees, the satellite is in the shadow area.

[0041] 4. Low-cost SADA structure

[0042] For low-cost SADA systems without conductive slip rings, mechanical limit switches are located on both sides of the SADA structure for limiting the SADA angle. A limit switch is located at each limit switch for angle positioning and calibration. The mechanical limit switches are positioned at 42° and 318° respectively. Simultaneously, soft limit switches are set in the SADA control software for the shaft angle, with limit values ​​of 50° and 310°. During normal rotation, the SADA angle is limited by the soft limit switches and will not trigger the limit switches. When the stepper motor rotates for a long time and the accumulated error becomes large, the shaft will trigger the limit switches at the mechanical limit switches to update and calibrate the angle information.

[0043] 5. Relationship between SADA angle and satellite frontal area

[0044] like Figure 2 As shown, when the SADA lock angle is 90°, the satellite's frontal area is at its maximum, and the air resistance it experiences is also at its maximum.

[0045] like Figure 3As shown, when the SADA lock angle is 180°, the satellite's frontal area is at its minimum, and the air resistance it experiences is also at its minimum.

[0046] 6. SADA's method for satellite phase adjustment

[0047] Small satellites equipped with SADA (Satellite Adaptor Assist) need to control the SADA to track the sun's azimuth angle in the sunlit area to drive the solar panels to orient themselves towards the sun and maintain onboard energy balance. In the shadow area, where there is no need for charging, the SADA can be maintained at any angle, providing greater design flexibility. The specific steps and methods are as follows:

[0048] In sunny areas, SADA still controls the angle to track the solar azimuth (e.g. Figure 1 As shown in the figure, the solar panels are aligned with the sun in real time to meet the energy balance requirements of the satellite, which is consistent with the conventional SADA control method.

[0049] In the shadow region, the SADA of different satellites is locked to a fixed angle (such as 90 degrees or 180 degrees) to ensure that the air resistance difference between different satellites is maximized, thereby achieving the effect of phase adjustment.

[0050] Because the atmospheric density is lower in the shadow region, it takes a long time to adjust the phase by relying solely on the drag difference in the shadow region. When there is a requirement for the phase adjustment time, it is necessary to sacrifice some of the charging time in the sunlit region. In this interval, SADA is also locked at a fixed angle to meet the requirement of completing the phase adjustment in a shorter time.

[0051] When controlling SADA, the solar azimuth angle is used as the control input. When the solar azimuth angle is greater than 67 degrees and less than 293 degrees, the solar azimuth angle is used as the desired tracking angle of SADA. When the solar azimuth angle is greater than 293 degrees or less than 67 degrees, a fixed angle is used as the desired holding angle of SADA. The phase adjustment time can be reduced by changing the solar azimuth angle determination threshold, such as increasing the determination threshold from 67 degrees to 115 degrees.

[0052] The above content includes multiple angles, such as 67 degrees, 293 degrees, and 115 degrees. Figure 1 As shown, these represent the angles traversed when rotating from the positive Z-axis of the celestial body towards the positive X-axis.

[0053] This invention has been verified in orbit in the Jilin-1-20 satellite project developed by Changguang Satellite Technology Co., Ltd. Figure 4The image shows the SADA telemetry data for one satellite over a day. It can be seen that when the solar azimuth angle is greater than 310 degrees or less than 115 degrees, SADA is locked at a fixed angle of 90 degrees. At other times, SADA tracks the solar azimuth angle to ensure solar panel charging. On-orbit test results indicate that the SADA control method can ensure long-term stable tracking of the solar panels by the solar azimuth angle, meeting onboard energy balance requirements. Furthermore, this method enabled 20 satellites to achieve a uniform, equal-phase distribution in the same orbit over a period of 5 months.

[0054] When the satellite attitude is stable on three axes relative to Earth for a long period of time, the control method of using SADA for satellite phase adjustment in this invention can enable microsatellites to control SADA to achieve solar panel orientation to the sun to meet the on-board energy balance, while also meeting the requirement to complete inter-satellite phase adjustment within a certain period of time.

[0055] When a satellite is in a sun-synchronous orbit and equipped with SADA, the control method of using SADA for satellite phase adjustment of the present invention can enable microsatellites to control the SADA angle in the sunlit area to achieve solar panel orientation to meet the on-board energy balance, while controlling the SADA to lock at different angles in the shadow area to adjust the windward area of ​​different satellites, thereby enabling satellites in the same orbit to complete inter-satellite phase adjustment within a period of time.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A control method for satellite phase adjustment using SADA, characterized in that, Includes the following steps: Step 1: In the sunlit area, the SADA control angle tracks the solar azimuth angle to ensure that the solar panels are oriented toward the sun in real time, meeting the energy balance requirements of the satellite; the solar azimuth angle is the angle between the projection of the solar vector on the XOZ plane of the satellite and the Z-axis of the satellite; Step 2: In the shadow area, different satellites are locked to a fixed angle by SADA to ensure that the difference in air resistance experienced by different satellites is maximized, thereby achieving the effect of phase adjustment; Step 3: When there is a requirement for phase adjustment time, SADA locks at a fixed angle to complete the phase adjustment within the expected time.

2. The control method for satellite phase adjustment using SADA according to claim 1, characterized in that, In step 1, when the solar azimuth angle is greater than the judgment threshold and less than the difference between 360 degrees and the judgment threshold, the satellite is determined to be in the sunshine area; when controlling SADA, the solar azimuth angle is used as the expected tracking angle of SADA.

3. The control method for satellite phase adjustment using SADA according to claim 1, characterized in that, Step 2 specifically involves determining that the satellite is in the Earth's shadow area when the difference between the solar azimuth angle and the judgment threshold is greater than 360 degrees or less than the judgment threshold. When controlling SADA, a fixed angle is used as the desired holding angle of SADA.

4. The control method for satellite phase adjustment using SADA according to claim 1, characterized in that, In step 1 and / or step 2, the threshold for determining the solar azimuth angle is 67 degrees.

5. The control method for satellite phase adjustment using SADA according to any one of claims 2-4, characterized in that, In step 1 and / or step 2, the phase adjustment time is reduced by increasing the threshold for determining the solar azimuth angle.

6. The control method for satellite phase adjustment using SADA according to claim 1 or 3, characterized in that, In step 2, the fixed angle to be locked is 90 degrees or 180 degrees.

7. The control method for satellite phase adjustment using SADA according to claim 1, characterized in that, In step 3, the fixed angle to be locked is 90 degrees or 180 degrees.

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