Method for reducing air resistance by horizontally arranging sailboards in earth shadow area

Abstract

The invention provides a method for reducing air resistance by horizontally arranging a sailboard in an earth shadow area, which can be applied to satellites of which solar wings continuously track the sun to obtain energy, in particular to ultra-low orbit earth pointing satellites with relatively large atmospheric resistance. Through recording or real-time calculation of an earth shadow area under a current track, the method enables a sailboard to rapidly capture a sailboard corner position with a minimum windward side when the sailboard enters the earth shadow area, then the sailboard is kept in a horizontal state, and a latest starting control point in the earth shadow area is calculated, so that the sailboard starts to rotate from the starting control point; the sailboard can directly face the sun when a satellite enters an illumination area. According to the method, the windward area of the satellite is reduced while satellite energy is not affected, so that orbit attenuation caused by atmospheric resistance to the satellite is reduced, and the purpose of saving fuel is achieved.

Description

Technical Field

[0001] The present invention relates to a method for reducing air resistance by placing a sailboard flat in an earth shadow area, which can be applied to satellites whose solar panels continuously track the sun to obtain energy, especially ultra-low orbit earth-pointing satellites with large atmospheric resistance, and belongs to the field of satellite control. Background Art

[0002] The configuration of the sailboard is relatively large, which makes the satellite's windward area larger while better receiving sunlight. For satellites in the shadow orbit, the shadow sailboard cannot provide energy for the satellite, but continues to bring greater air resistance to the satellite, especially for ultra-low orbit satellites with greater atmospheric density. Therefore, it is necessary to invent a method for placing the sailboard in the shadow area horizontally, which can reduce the satellite's windward area without affecting the satellite's energy, thereby reducing the orbital attenuation caused by atmospheric resistance, thereby achieving the purpose of saving fuel. The current method to reduce the air resistance caused by the sailboard is to use a solar wing fixed horizontal installation method, which has the disadvantage of low solar energy utilization. In order to ensure the satellite's energy, it is necessary to configure a larger solar sailboard and a heavier power system, which increases the weight of the satellite and makes the sailboard more flexible, affecting the satellite's stable control. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a method for reducing air resistance by placing a sailboard flat in a ground shadow area, thereby achieving the purpose of reducing air resistance in the ground shadow area by placing the sailboard flat in the ground shadow area at the position where the sailboard has the smallest windward side angle.

[0004] The technical solution of the present invention is: first, a method for reducing air resistance by placing a sailboard flat in the shadow area is provided, in each orbital cycle:

[0005] The time T1 required to change from PA to the corresponding sailboard reference turning angle PO when the sailboard is in a horizontal state is calculated using the sailboard reference turning angle PA recorded in the previous track when the sailboard enters the earth's shadow; the horizontal state of the sailboard is the state when the windward area of ​​the sailboard is the smallest when the sailboard is in the earth's shadow area;

[0006] Calculate the sailboard reference angle PC corresponding to the front sailboard control point in the ground shadow area;

[0007] Calculate the time required to turn from the board control point PC to the board reference turning angle PB when entering the illumination area;

[0008] The current sailboard reference angle is determined in real time. When the current sailboard reference angle is equal to the sailboard reference angle PA recorded at the time of entering the earth's shadow in the previous orbital cycle, a sailboard driving instruction is sent to rotate the sailboard at the sailboard integrated angular velocity ω1 for time T1 to reach the sailboard reference angle PO corresponding to the horizontal state; when the sailboard reference angle is equal to the sailboard reference angle PC at the sailboard starting control point, a sailboard driving instruction is sent to rotate the sailboard at the sailboard integrated angular velocity ω1 for time T3;

[0009] When the satellite enters the earth's shadow, the sailboard reference angle PA at the time the satellite enters the earth's shadow is updated; when the satellite leaves the earth's shadow, the sailboard reference angle PB at the time the satellite enters the illuminated area is updated.

[0010] Preferably, the reference turning angle of the sailboard is a theoretical angle between the projection of the sailboard normal line in the orbital plane and the projection of the sun in the orbital plane; when the angle between the sailboard normal line and the sun vector is the smallest, the sailboard is best exposed to the sun;

[0011] The base angle of the sailboard changes continuously as the sun moves around the satellite, and its range of change is 0 to 360°.

[0012] Preferably, the rate of change of the sailboard reference rotation angle during normal sun tracking is the orbital angular velocity ω0. For low earth orbit satellites, the orbital angular velocity ω0 is between 0.06° / s and 0.07° / s.

[0013] Preferably, T1 is calculated as follows:

[0014]

[0015] Wherein: mod represents Kstate*(PO-PA) modulo 360; Kstate is the flight state of the satellite, Kstate=1 when the satellite is flying forward, and Kstate=-1 when the satellite is flying backward.

[0016] Preferably, the calculation method of the sailboard reference angle PC corresponding to the sailboard starting point before the satellite leaves the ground shadow is:

[0017] PC=mod(PB-Kstate*T3*ω f ,360)

[0018] where mod represents PB-Kstate*T3*ω f Modulo 360; Kstate is the satellite flight state, Kstate = 1 when the satellite is flying forward, and Kstate = -1 when the satellite is flying backward; ω f is the specified sailboard driving angular velocity, ω f >2ω0, the value is positive.

[0019] Preferably, the calculation method of T3 is:

[0020]

[0021] In the above formula, mod represents Kstate*(PB-PA) modulo 360; Kstate is the flight state of the satellite, Kstate=1 when the satellite is flying forward, and Kstate=-1 when the satellite is flying backward; ω f is the specified sailboard driving angular velocity, ω f>2ω0.

[0022] Preferably, the windsurfing board integrated angular velocity ω1=Kstate*ω f ,in:

[0023] Kstate is the flight state of the satellite. When the satellite is flying forward, Kstate=1; when the satellite is flying backward, Kstate=-1; ω f is the specified sailboard driving angular velocity, ω f >2ω0.

[0024] Preferably, ω f It is the absolute value of the angular velocity specified during the rotation process of the windsurfing board from the starting control point PC to the reference turning angle PB of the windsurfing board when it enters the illumination area.

[0025] In a second aspect, a terminal device is provided, including:

[0026] a memory for storing instructions executed by at least one processor;

[0027] The processor is used to execute the instructions stored in the memory to implement the method of reducing air resistance by placing the sailboard flat in the ground shadow area.

[0028] In a third aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer is caused to execute the above-mentioned method of reducing air resistance by placing a sailboard flat in a ground shadow area.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) In the Earth's shadow, the satellite's attitude is adjusted to minimize the windward surface of the sailboard, thereby reducing the orbital attenuation caused by atmospheric resistance in the Earth's shadow, saving fuel without affecting the satellite's energy;

[0031] (2) The control strategy is based on pure algorithms, which does not require any additional hardware and has little impact on the stability of the satellite.

[0032] (3) It has good portability and is suitable for satellites in shadow areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the method for laying out a sailboard in a ground shadow area according to the present invention;

[0034] Figure 2 Schematic diagram of the control strategy for the horizontal placement of the satellite sailboard in the upright flight of the present invention

[0035] Figure 3 It is a schematic diagram of the horizontal placement control strategy of the satellite inverted flying sailboard of the present invention. DETAILED DESCRIPTION

[0036] The present invention provides a method for reducing air resistance by placing a sailboard flat in a ground shadow area. The purpose of reducing air resistance in the ground shadow area is achieved by placing the sailboard flat at the smallest sailboard turning angle on the windward side in the ground shadow area.

[0037] To implement the above technology, Figure 1 As shown, the present invention is implemented through the following technical process:

[0038] The following are recorded in orbit: the reference angle PA of the sailboard when the satellite enters the earth's shadow in each orbit, and the reference angle PB of the sailboard when the earth's shadow enters the light.

[0039] The first step is to calculate the time T1 required from the reference angle PA of the sailboard at the time of entering the earth's shadow to the reference angle PO of the sailboard corresponding to the minimum windward area of ​​the sailboard, starting from each orbital cycle; the reference angle PA of the sailboard at the time of entering the earth's shadow is the data recorded in the previous orbit;

[0040] The meaning of the sailboard reference angle is:

[0041] The theoretical angle between the projection of the sailboard normal in the orbital plane and the projection of the sun in the orbital plane. When the actual sailboard rotation angle is equal to the sailboard reference angle, it can be considered that the angle between the sailboard normal and the sun vector is the smallest, and the sailboard is best exposed to the sun. The sailboard reference rotation angle changes continuously with the movement of the sun around the satellite, and its range of change is 0-360°. Its rate of change during normal tracking of the sun is the orbital angular velocity ω0. When the satellite is flying forward, the satellite flight state Kstate=1, and when the satellite is flying backward, the satellite flight state Kstate=-1, then the sailboard reference angle change rate is Kstate*ω0. For low-Earth orbit satellites, the orbital angular velocity ω0 is between 0.06 and 0.07° / s.

[0042] The state of the sailboard when its windward area is the smallest is called the flat state, and the reference turning angle of the sailboard corresponding to the flat state is PO;

[0043] There are two kinds of horizontal states of the sailboard, one of which is: the satellite is between the earth and the sun, at which time the satellite is in the sunlit area and the sailboard is exposed to the sun; the other is: the earth is between the satellite and the sun, the satellite is in the earth's shadow area, and the sailboard is not exposed to the sun; the present invention selects the horizontal state of the sailboard when the satellite is in the earth's shadow area.

[0044] Let the orbital angular velocity be ω0 and the specified sailboard driving angular velocity be ω f , the time required to drive the sailboard from the current reference angle PA to PO is T1:

[0045]

[0046] Wherein: mod represents Kstate*(PO-PA) modulo 360.

[0047] The second step is to calculate the sailboard reference angle PC corresponding to the sailboard starting point before the earth shadow area. The sailboard starting point before leaving the earth shadow area refers to the time point when the sailboard starts to rotate from the flat state to the sailboard reference angle PB when entering the illumination area. It is the latest time point when the sailboard is controlled to rotate around the rotation axis before the satellite leaves the earth shadow area so that the sailboard faces the sun when entering the illumination area. It is intended to keep the sailboard in the flat state in the earth shadow area for as long as possible, and at the same time, the sailboard captures the sailboard reference angle when entering the illumination area to obtain sunlight, thereby achieving the purpose of not affecting the energy of the entire satellite.

[0048] Specifically, when the base turning angle of the sailboard is in the interval [PA, PC], the sailboard is in a flat state with the smallest windward area, achieving the purpose of reducing atmospheric resistance in the shadow area, and can immediately obtain sunlight when entering the illuminated area; the calculation method of PC is:

[0049] PC=mod(PB-Kstate*T3*ω f ,360)

[0050] The third step is to calculate the time T3 required for the sailboard to be driven to the sailboard reference turning angle PB from the control point PC in the shadow area to the illuminated area; the calculation method of T3 is:

[0051]

[0052] The fourth step is to execute the horizontal control strategy of the sailboard: judge the current sailboard reference angle in real time, and send the sailboard drive command when the current sailboard reference angle is equal to the sailboard reference angle PA recorded at the time of entering the earth's shadow in the previous orbital cycle, so that the sailboard reaches the horizontal angle PO at the comprehensive angular velocity ω1 time T1; when the sailboard reference angle is equal to the sailboard starting control point PC, send the sailboard drive command to drive the sailboard at the specified angular velocity time T3; the mathematical expression of the sailboard comprehensive angular velocity ω1 is Kstate*ω f The control strategy of keeping the sailboard level when the satellite is flying is as follows: Figure 2 As shown in the figure, the control strategy of keeping the sailboard horizontal during inverted flight is as follows Figure 3 shown.

[0053] The fifth step is to update in real time the sailboard reference angle PA when entering the earth's shadow in the current cycle and the sailboard reference angle PB when entering the illuminated area from the earth's shadow, and complete the control of keeping the sailboard flat in the earth's shadow area to reduce air resistance in one orbital cycle.

[0054] In a second aspect, a terminal device is provided, including:

[0055] a memory for storing instructions executed by at least one processor;

[0056] The processor is used to execute the instructions stored in the memory to implement the method of reducing air resistance by placing the sailboard flat in the ground shadow area.

[0057] In a third aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer is caused to execute the above-mentioned method of reducing air resistance by placing a sailboard flat in a ground shadow area.

[0058] Example:

[0059] 1. Calculate the time T1 required from the reference angle PA of the sailboard when entering the earth's shadow to the minimum reference angle PO of the sailboard on the windward side;

[0060] Taking a satellite flying over the earth at an orbital altitude of 407 km as an example, its corresponding orbital angular velocity is 0.0647° / s, and its specified angular velocity when driven to the horizontal angle position is 0.6° / s. Its corresponding horizontal angle PO is parallel to the satellite flight direction at 180°, so:

[0061]

[0062] 2. Calculate the time T3 required for the sailboard to be captured from the starting control point PC to the reference turning angle PB of the sailboard when it enters the illumination area;

[0063]

[0064] 3. Calculate the control point PC of the sailboard in the front shadow area, so that the sailboard can capture the reference angle when entering the light, obtain sunlight, and thus achieve the purpose of not affecting the energy of the whole star. Then the reference angle is in the interval [PA, PC], and the sailboard is in a 180° flat state. At this time, the windward area of ​​the sailboard is the smallest, achieving the purpose of reducing atmospheric resistance;

[0065] PC=PB-T3*0.6

[0066] 4. Execute the windsurfing horizontal control strategy, and judge in real time whether the windsurfing reference angle reaches the reference angle PA recorded at the last time of entering the earth's shadow. If so, execute the horizontal strategy, otherwise continue to judge;

[0067] 5. Update the reference angle PA of the sailboard when it enters the earth's shadow and the reference angle PB of the sailboard when it enters the light from the earth's shadow in real time.

[0068] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A method for reducing air resistance by placing a sailboard flat in a ground shadow area, characterized in that include: During each orbital period: The time T1 required to change from PA to the corresponding sailboard reference turning angle PO when the sailboard is in a horizontal state is calculated using the sailboard reference turning angle PA recorded in the previous track when the sailboard enters the earth's shadow; the horizontal state of the sailboard is the state when the windward area of ​​the sailboard is the smallest when the sailboard is in the earth's shadow area; Calculate the sailboard reference angle PC corresponding to the front sailboard control point in the ground shadow area; Calculate the time required to turn from the board control point PC to the board reference turning angle PB when entering the illumination area; The current sailboard reference angle is determined in real time. When the current sailboard reference angle is equal to the sailboard reference angle PA recorded at the time of entering the earth's shadow in the previous orbital cycle, a sailboard driving instruction is sent to rotate the sailboard at the sailboard integrated angular velocity ω1 for time T1 to reach the sailboard reference angle PO corresponding to the horizontal state; when the sailboard reference angle is equal to the sailboard reference angle PC at the sailboard starting control point, a sailboard driving instruction is sent to rotate the sailboard at the sailboard integrated angular velocity ω1 for time T3; When the satellite enters the earth's shadow, the sailboard reference angle PA at the time the satellite enters the earth's shadow is updated; when the satellite leaves the earth's shadow, the sailboard reference angle PB at the time the satellite enters the illuminated area is updated.

2. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 1, characterized in that: The reference turning angle of the sailboard is the theoretical angle between the projection of the sailboard normal line in the orbital plane and the projection of the sun in the orbital plane; when the angle between the sailboard normal line and the sun vector is the smallest, the sailboard is best exposed to the sun; The base angle of the sailboard changes continuously as the sun moves around the satellite, and its range of change is 0 to 360°.

3. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 2, characterized in that: The rate of change of the sailboard reference rotation angle during normal sun tracking is the orbital angular velocity ω0. For low-Earth orbit satellites, the orbital angular velocity ω0 is between 0.06° / s and 0.07° / s.

4. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 1, characterized in that: The calculation method of T1 is: Wherein: mod represents Kstate*(PO-PA) modulo 360; Kstate is the flight state of the satellite, Kstate=1 when the satellite is flying forward, and Kstate=-1 when the satellite is flying backward.

5. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 3, characterized in that: The calculation method of the sailboard reference angle PC corresponding to the sailboard control point before the satellite leaves the earth's shadow is: PC=mod(PB-Kstate*T3*ω f ,360) where mod represents PB-Kstate*T3*ω f Modulo 360; Kstate is the satellite flight state, Kstate = 1 when the satellite is flying forward, and Kstate = -1 when the satellite is flying backward; ω f is the specified sailboard driving angular velocity, ω f >2ω0, the value is positive.

6. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 3, characterized in that: The calculation method of T3 is: In the above formula, mod represents Kstate*(PB-PA) modulo 360; Kstate is the flight state of the satellite, Kstate=1 when the satellite is flying forward, and Kstate=-1 when the satellite is flying backward; ω f is the specified sailboard driving angular velocity, ω f >2ω0.

7. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to claim 1, characterized in that: The overall angular velocity of the windsurfing board ω1=Kstate*ω f ,in: Kstate is the flight state of the satellite. When the satellite is flying forward, Kstate=1; when the satellite is flying backward, Kstate=-1; ω f is the specified sailboard driving angular velocity, ω f >2ω0.

8. The method for reducing air resistance by placing a sailboard flat in a ground shadow area according to any one of claims 5 to 7, characterized in that: ω f It is the absolute value of the angular velocity specified during the rotation process of the windsurfing board from the starting control point PC to the reference turning angle PB of the windsurfing board when it enters the illumination area.

9. A terminal device, characterized in that: include: a memory for storing instructions executed by at least one processor; A processor, configured to execute instructions stored in a memory to implement a method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer is enabled to execute the method according to any one of claims 1 to 8.

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