Maneuvering method considering sunlight avoidance based on intermediate parking attitude

Abstract

A maneuvering method considering sunlight avoidance based on a middle parking attitude belongs to the technical field of spacecraft attitude control, and comprises the following steps: calculating a minimum included angle between a camera optical axis and sunlight in a maneuvering process according to the pointing direction of the camera optical axis when maneuvering starts and ends; and if the minimum included angle is smaller than a set threshold value and maneuvering needs to be completed quickly, designing a satellite middle parking attitude, so that the included angle between the optical axis of the camera and the sunlight is always larger than the set threshold value in the maneuvering process of the satellite according to the initial attitude-middle parking attitude-tail end attitude. The method is realized by applying spherical geometric analysis design based on the assumption that the included angles of the rotating shaft, the sun vector and the camera optical axis are unchanged, and is small in calculation amount, simple and practical.

Description

Technical Field

[0001] The invention relates to a maneuvering method based on an intermediate parking attitude and taking sunlight avoidance into consideration, belonging to the technical field of spacecraft attitude control. Background Art

[0002] There are currently two types of sunlight avoidance maneuvers. One is to determine whether to perform sunlight avoidance and the current sunlight avoidance target attitude angle based on the relationship between the camera optical axis, satellite attitude and solar vector direction at the current moment. When this method is used for sunlight avoidance in any rapid maneuvering mission, sunlight avoidance estimation and attitude setting are required at each step. The other is to set the sunlight avoidance as an attitude restricted zone before the maneuver begins, and use optimization algorithms such as particle swarm to plan the maneuver path. This type of method has a large amount of computation and is not conducive to onboard implementation. 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 maneuvering method based on an intermediate parking posture taking sunlight avoidance into consideration, based on the assumption that the angle between the rotation axis and the sun vector and the camera optical axis is constant, and is implemented by applying spherical geometry analysis design, thereby shortening the maneuvering time, requiring little calculation, and being simple and practical.

[0004] The technical solution of the present invention is: a maneuvering method based on an intermediate parking posture that takes sunlight avoidance into consideration, comprising: judging whether the current maneuvering path of the spacecraft satisfies a preset sunlight avoidance constraint; if not, setting a maneuvering path that satisfies the sunlight avoidance requirement according to the maneuvering time requirement; when the maneuvering time is not less than the preset time, setting the maneuvering path of the spacecraft to a reverse maneuvering path; when the maneuvering time is less than the preset time, calculating the target posture at the point where the angle between the optical axis of the spacecraft camera and the sunlight is the smallest, adjusting the camera optical axis posture according to the sunlight avoidance constraint, and setting the intermediate parking posture of the spacecraft that satisfies the preset sunlight avoidance constraint according to the orientation of the camera in the spacecraft system, and setting the maneuvering path of the spacecraft to be a maneuvering path from the initial posture to the intermediate parking posture and a maneuvering path from the intermediate parking posture to the target posture in sequence.

[0005] Furthermore, the reverse maneuvering path is to reverse the rotation axis and set the maneuvering angle to 2π-original maneuvering angle.

[0006] Further, the setting of the intermediate parking posture that satisfies the preset sunlight avoidance constraint includes:

[0007] The axis whose angle with the camera optical axis remains unchanged during the maneuver is selected as the rotation axis. The rotation angle θ is designed according to the relationship between the angle α between the rotation axis and the sun direction vector and the angle β between the rotation axis and the camera optical axis direction vector. t ;

[0008] Select the attitude when the angle between the camera optical axis and the sun direction vector does not satisfy the sunlight avoidance constraint as the target attitude, and rotate the target attitude along the normal of the plane where the sun and the original rotation axis are located by θ t , and obtain the intermediate parking posture.

[0009] Furthermore, the rotation angle θ t The absolute value of is ε-|α-β|+Δε, θ t The sign of and the direction of the plane normal should be chosen so that the angle between the camera optical axis and the sun after the target posture is rotated is ε+Δε. Δε is the set margin angle, which is 0 by default.

[0010] Furthermore, the preset sunlight avoidance constraint includes: constructing a sphere with the rotation axis as the North Pole and the sun direction vector defining zero longitude, expressing the camera position with longitude and latitude, and when the longitude of the camera at the start of the maneuver is in the interval (0, π) and the maneuvering angle Φ is greater than γ, sunlight avoidance is required during the maneuvering process; wherein α is the angle between the rotation axis and the sun direction vector, β is the angle between the rotation axis and the camera optical axis direction vector, and ε is the lower limit threshold of the angle between the camera optical axis and the sun direction vector.

[0011] Furthermore, the longitude of the camera is γ=atan2(X xu (1),X xu (0)); where X xu (0) is the projection of the camera optical axis on the X axis of the rotation axis coordinate system, xu (1) is the projection of the camera optical axis on the Y axis of the rotation axis coordinate system.

[0012] Furthermore, the Z axis of the rotation axis coordinate system is the rotation axis, the Y axis is the cross product of the rotation axis and the sun vector, and X is determined by the right-hand rule.

[0013] Furthermore, if |α-β|>, or |α-β|<, and the camera optical axis direction vector is always more than a preset distance away from the sun direction vector and the plane where the rotation axis is located, it is determined that the camera will not be exposed to the sun during the maneuver.

[0014] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of a maneuvering method based on an intermediate parking posture and taking sunlight avoidance into consideration are implemented.

[0015] A maneuvering device based on an intermediate parking posture that takes sunlight avoidance into consideration comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the maneuvering method based on an intermediate parking posture that takes sunlight avoidance into consideration when executing the computer program.

[0016] The advantages of the present invention compared with the prior art are:

[0017] (1) The present invention realizes the calculation of the minimum angle between the camera optical axis and the sun direction vector during the maneuvering process by constructing a rotating coordinate system;

[0018] (2) The present invention achieves a fast maneuvering path setting that meets sunlight avoidance conditions by setting an intermediate parking posture. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0020] Figure 1 This is a schematic diagram of the spatial relationship between the sun, the camera optical axis, and the rotation axis of the present invention;

[0021] Figure 2 A schematic diagram of the maneuvering path setting with sunlight avoidance of the present invention (green indicates the maneuvering path is reversed, and orange indicates the intermediate parking posture);

[0022] Figure 3 This is a curve diagram of the angle between the sun and the camera when there is no sunlight in an embodiment of the present invention;

[0023] Figure 4 This is a curve diagram of the angle between the sun and the camera for avoiding the slow sunlight in an embodiment of the present invention;

[0024] Figure 5 This is a curve diagram of the angle between the sun and the camera for fast sunlight avoidance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to better understand the above technical scheme, the technical scheme of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical scheme of the present invention, rather than limitations on the technical scheme of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0026] The following is a further detailed description of a maneuvering method based on an intermediate parking posture and considering sunlight avoidance provided by an embodiment of the present invention in conjunction with the accompanying drawings of the specification. The specific implementation method may include:

[0027] Step 1: Determine whether the simple maneuver path satisfies the sunlight avoidance constraint

[0028] like Figure 1 , Figure 2As shown in the figure, during the maneuver, the angle α between the rotation axis and the sun direction vector and the angle β between the rotation axis and the camera optical axis direction vector remain unchanged. If |α-β|>ε, or |α-β|<ε but the camera optical axis direction vector is always far away from the plane where the sun direction vector and the rotation axis are located, that is, the SOE plane, then it is considered that the camera will not be exposed to the sun during the maneuver. The camera longitude γ is actually the angle between the SOE plane and the COE plane, which satisfies:

[0029] ∠SOC=acos(cosα·cosβ·cosγ+sinα·sinβ)

[0030] The above formula can be used to detect whether the current posture and target posture meet the sunlight avoidance requirements.

[0031] Project the sun vector and the camera vector to the rotation axis coordinate system (the Z axis is the rotation axis, the Y axis is the cross product of the rotation axis and the sun vector, and the sun vector is located in the XOZ plane of the rotation axis coordinate system). bxu It is obtained from the following formula:

[0032]

[0033] Convert the camera optical axis to the rotation axis coordinate system:

[0034]

[0035] Since the sun vector is located in the rotation axis coordinate system C bxu In the XOZ plane, that is, the longitude and latitude are used to represent the sun's position, then the sun's longitude is 0, and the camera's longitude is calculated as:

[0036] γ=atan2(X xu (1),X xu (0))

[0037] Since the angles calculated before the maneuver planning to avoid the sun are all less than π radians, when the longitude γ of the camera is in the interval (0, π) and the maneuver angle Φ is greater than γ, the maneuver process needs to avoid the sun. Where is the lower limit threshold of the angle between the camera optical axis and the sun.

[0038] Step 2: According to the maneuvering time requirements, set a maneuvering path that meets the sun avoidance requirements.

[0039] If the maneuvering time is sufficient, the reverse maneuvering path is selected, that is, the rotation axis is reversed, and the maneuvering angle is set to 2π-the original maneuvering angle.

[0040] If rapid maneuvering is required, the target posture at the point where the angle between the camera optical axis and the sun is the smallest needs to be calculated. The longitude of the camera optical axis at the target posture is 0. The intermediate parking posture and the corresponding maneuvering path that meet the angle constraint are designed: the axis perpendicular to the camera optical axis is selected as the rotation axis, and the rotation angle θ is designed according to the size relationship between α and β. t . Rotate the target attitude along the normal of the plane where the sun and the original rotation axis are located by θ t , and get the intermediate parking posture. Set the maneuver path to 2 sections, the first section is from the initial posture to the intermediate parking posture, and the second section is from the intermediate parking posture to the target posture.

[0041] The solution provided in the embodiment of the present invention specifically includes:

[0042] Step 1: Predict and detect the angle between the sun and the camera during maneuvers

[0043] In practice, the rotation axis can be expressed as the maneuvering four-element q from the target to the main body. bT Find out that the expressions of the sun direction vector and the camera direction vector in the satellite mechanical coordinate system are S b =[S bx ,S by ,S bz ] T and C b The steps for predicting and detecting the angle between the sun and the camera during maneuvering are as follows:

[0044] According to the maneuverable four-element q bT Calculate the representation of the dynamic axis in the body:

[0045]

[0046] The maneuvering angle is:

[0047] Φ=2acos(q bT (3))

[0048] Calculate the angles between the rotation axis and the camera and the sun:

[0049]

[0050] When the camera optical axis is the satellite mechanical system + X axis, Cb = [1, 0, 0], and β can be simplified to acos(E 1e ). When |α-β| is greater than the given protection angle, there is no need to avoid sunlight. Otherwise, it is necessary to determine whether there is sunlight in the maneuvering path. The judgment algorithm is as follows:

[0051] Project the sun vector and the camera vector to the rotation axis coordinate system (the Z axis is the rotation axis, the Y axis is the cross product of the rotation axis and the sun vector, and the sun vector is located in the XOZ plane of the rotation axis coordinate system).bxu It is obtained from the following formula:

[0052]

[0053] Convert the camera optical axis to the rotation axis coordinate system:

[0054]

[0055] Since the sun vector is located in the rotation axis coordinate system C bxu In the XOZ plane, that is, the longitude and latitude are used to represent the sun's position, then the sun's longitude is 0, and the camera's longitude is calculated as:

[0056] γ=atan2(X xu (1),X xu (0))

[0057] Since the angles calculated before sunlight avoidance in maneuver planning are all less than π radians, when the longitude γ of the camera is in the interval (0, π) and the maneuvering angle Φ is greater than γ, sunlight avoidance is required during the maneuvering process.

[0058] Step 2: Sunlight avoidance re-planning during maneuvers

[0059] After detecting that sunlight avoidance is required during the maneuver, the maneuver path needs to be replanned. The detection angle of the slow sunlight avoidance maneuver is 60 degrees. If sunlight avoidance is required, a large circle maneuver is used to avoid the sunlight; the detection angle of the fast sunlight avoidance maneuver is 3 degrees. If sunlight avoidance is required, an intermediate attitude parking point is designed along the way, so that one maneuver becomes two maneuvers.

[0060] The following mainly introduces the design algorithm of the intermediate posture parking point.

[0061] Input the target to the main body's maneuvering four-element q bT , the transformation matrix C from the rotation axis coordinate system to this system bxu , the angle between the rotation axis and the sun α, the angle between the rotation axis and the camera β, the longitude of the camera γ, the direction cosine matrix C from the inertial system to the system bi . Calculate the avoidance parking posture during the maneuver (give the direction cosine matrix C of the relative inertia of the avoidance parking posture ti_new ), first maneuver to this posture, and then maneuver to the target posture to ensure the sun avoidance requirement.

[0062] First, calculate the target attitude 1 when the satellite rotates around the rotation axis to the point where the camera optical axis is closest to the sun vector (the angle around the rotation axis is the longitude γ of the camera at this time). The direction cosine of this attitude to the body attitude is expressed as C _btemp

[0063]

[0064] C _btemp =q2DCM(q bTemp )

[0065] Rotate the target posture 1 around the Y axis of the rotation axis coordinate system by θ again t The target attitude 2 is obtained by the angle, so that the angle between the X axis of the target attitude 2 and the sun is the protection angle d (5 degrees). To obtain the target attitude 2, the following calculations need to be performed:

[0066] The Y axis of the rotation axis coordinate system is represented in target posture 1:

[0067]

[0068] If the angle α between the rotation axis and the sun is greater than the angle β between the rotation axis and the camera, then:

[0069] θ t =γ-α+β

[0070] At this time, the maneuvering four elements from target posture 2 to target posture 1 can be obtained by the following formula:

[0071]

[0072] If the angle α between the rotation axis and the sun is not greater than the angle β between the rotation axis and the camera, then:

[0073] θ t =γ+α-β

[0074] At this time, the maneuvering four elements from target posture 2 to target posture 1 can be obtained by the following formula:

[0075]

[0076] Then calculate the direction cosine matrix C of the relative inertia of the avoidance parking posture (i.e. target posture 2) Ti_new have;

[0077] C _tempT_new =q2DCM(q TempT_new )

[0078] C ti_new =C T _TempT_new C T bTemp C bi

[0079] Simulation verification of fast and slow sun avoidance plans Figure 3 , 4 , as shown in Figure 5.

[0080] Figure 3During the maneuver, the angle between the camera optical axis and the sun direction vector first decreases and then increases, with the minimum angle being 1.278°, which does not meet the sunlight avoidance condition.

[0081] Figure 4 In the figure, the maneuvering path of the camera optical axis is Figure 3 On the contrary, during the maneuver, the angle between the camera optical axis and the sun direction vector first increases and then decreases, satisfying the sunlight avoidance condition.

[0082] Figure 5 In the figure, the maneuvering path of the camera optical axis is Figure 3 There is little change in the image, among which the minimum angle between the camera optical axis and the sun direction vector is 5.045°, and the moment with the minimum angle is the intermediate parking posture.

[0083] The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer executes Figure 1 The method described.

[0084] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0085] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0088] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0089] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A maneuvering method based on an intermediate parking posture taking sunlight avoidance into consideration, characterized in that: include: Determine whether the spacecraft's current maneuvering path meets the preset sunlight avoidance constraints; If not, a maneuvering path that meets the sun avoidance requirement is set based on the maneuvering time requirement; When the maneuvering time is not less than the preset time, the maneuvering path of the spacecraft is set to the reverse maneuvering path; when the maneuvering time is less than the preset time, the target attitude at the point where the angle between the optical axis of the spacecraft camera and the sunlight is the smallest is calculated, and the camera optical axis attitude is adjusted according to the sunlight avoidance constraint, and the intermediate parking attitude of the spacecraft that meets the preset sunlight avoidance constraint is set according to the orientation of the camera in the spacecraft system, and the maneuvering path of the spacecraft is set to the maneuvering path from the initial attitude to the intermediate parking attitude and the maneuvering path from the intermediate parking attitude to the target attitude.

2. A method of maneuvering based on an intermediate parking posture and taking sunlight avoidance into consideration according to claim 1, characterized in that: The reverse maneuvering path is to reverse the rotation axis and set the maneuvering angle to 2π-original maneuvering angle.

3. The method of maneuvering based on the intermediate parking posture and considering sunlight avoidance according to claim 1, characterized in that: The setting of the intermediate parking posture that satisfies the preset sunlight avoidance constraint includes: The axis whose angle with the camera optical axis remains unchanged during the maneuver is selected as the rotation axis. The rotation angle θ is designed according to the relationship between the angle α between the rotation axis and the sun direction vector and the angle β between the rotation axis and the camera optical axis direction vector. t ; Select the attitude when the angle between the camera optical axis and the sun direction vector does not satisfy the sunlight avoidance constraint as the target attitude, and rotate the target attitude along the normal of the plane where the sun and the original rotation axis are located by θ t , and obtain the intermediate parking posture.

4. The method of maneuvering based on the intermediate parking posture and considering sunlight avoidance according to claim 3, characterized in that: The rotation angle θ t The absolute value of is ε-|α-β|+Δε, θ t The sign of and the direction of the plane normal should be chosen so that the angle between the camera optical axis and the sun after the target posture is rotated is ε+Δε; Δε is the set margin angle, which is 0 by default.

5. The method of maneuvering based on intermediate parking posture and considering sunlight avoidance according to claim 1, characterized in that: The preset sunlight avoidance constraint includes: constructing a sphere with the rotation axis as the North Pole and the sun direction vector defining zero longitude, expressing the camera position in longitude and latitude, and when the longitude of the camera at the start of the maneuver is in the interval (0, π) and the maneuvering angle Φ is greater than γ, sunlight avoidance is required during the maneuvering process; wherein α is the angle between the rotation axis and the sun direction vector, β is the angle between the rotation axis and the camera optical axis direction vector, and ε is the lower limit threshold of the angle between the camera optical axis and the sun direction vector.

6. A method of maneuvering based on an intermediate parking posture and taking sunlight avoidance into consideration according to claim 5, characterized in that: The longitude of the camera is γ=atan2(X xu (1),X xu (0)); where X xu (0) is the projection of the camera optical axis on the X axis of the rotation axis coordinate system, xu (1) is the projection of the camera optical axis on the Y axis of the rotation axis coordinate system.

7. A method of maneuvering based on an intermediate parking posture and taking sunlight avoidance into consideration according to claim 6, characterized in that: The Z axis of the rotation axis coordinate system is the rotation axis, the Y axis is the cross product of the rotation axis and the sun vector, and X is determined by the right-hand rule.

8. The method of maneuvering based on the intermediate parking posture and considering sunlight avoidance according to claim 6, characterized in that: If |α-β|>, or |α-β|<, and the camera optical axis direction vector is always more than a preset distance away from the sun direction vector and the plane where the rotation axis is located, it is determined that the camera will not be exposed to the sun during the maneuver.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A mobile device based on an intermediate parking posture and considering sunlight avoidance, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

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