A normal vector-based follow-look pose maneuver path planning method

Abstract

The application discloses a normal vector-based follow-sighting attitude maneuver path planning method, and belongs to the technical field of spacecraft attitude control, and comprises the following steps: at any time during the follow-sighting maneuver, a camera optical axis is aligned with a target, and a satellite body axis perpendicular to the camera optical axis is set to point to a set normal vector direction, the set normal vector direction is set according to maneuver capability and pointing requirement, and the setting basis is that the body axis is in the set normal vector direction; the set normal vector direction is determined according to the follow-sighting task, and includes four cases, namely, keeping data transmission, keeping energy, keeping maneuver and keeping imaging. The normal vector of the plane formed by the target pointing and the ground pointing is applied, and the target attitude setting during the antenna data transmission to the ground while the follow-sighting is realized.

Description

Technical Field

[0001] This invention relates to a tracking and aiming attitude maneuvering path planning method based on normal vectors, belonging to the field of spacecraft attitude control technology. Background Technology

[0002] When a satellite with flexible attachments performs attitude maneuvers, maneuver path planning is required. In tracking and aiming missions, the target position changes over time, thus the maneuver path planning problem is reduced to the target attitude calculation problem at each moment. The primary constraint on the target attitude is to achieve tracking and aiming, i.e., aligning the camera's optical axis with the target; the secondary constraints are the requirements for preserving data transmission and power.

[0003] To preserve data transmission, the angle between the antenna pointing towards the Earth should be as small as possible. If the antenna is perpendicular to the camera's optical axis, but the target and the Earth are not perpendicular, the angle between the antenna pointing towards the Earth is minimized when the antenna, camera optical axis, and Earth are in the same plane, while ensuring tracking and aiming. To ensure energy efficiency, the direction of sunlight should be as close as possible to the normal direction of the solar panel, i.e., perpendicular to the solar panel's axis of rotation. In this case, the angle between the direction of sunlight and the solar panel's normal direction is minimized when the solar panel's normal, camera optical axis, and the sun are in the same plane, assuming the solar panel's position on its own axis remains constant.

[0004] When the target's line-of-sight angular velocity is large, the tracking constraint must be ensured first. Considering that the tracking time for a single target is much shorter than the geostationary orbit period, the relative path of the local satellite to the target during tracking can be assumed to be within a plane. To ensure maneuver speed, the minimum inertia axis is aligned with the plane normal vector for maneuver path planning. When the target's line-of-sight angular velocity is at its maximum, the imaging axis must remain stationary to improve imaging quality. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a tracking attitude maneuver path planning method based on normal vectors. It gives the selection of normal vectors and target attitude settings in four cases: data transmission preservation, energy preservation, maneuver preservation, and imaging preservation. Data transmission preservation means that the angle between the antenna pointing and the direction pointing to the earth should be as small as possible. Energy preservation means that the angle between the normal of the solar panel and the direction of sunlight should be as small as possible. Maneuver preservation means that the maneuverability should be used as much as possible in the direction of tracking the target. Imaging preservation means that the camera does not rotate around the optical axis, but only sets the Euler angles of the other two axes.

[0006] The technical solution of this invention is: a path planning method for tracking and aiming attitude maneuvers based on normal vectors. At any moment during the tracking and aiming maneuver, the camera optical axis is aligned with the target. The direction of the satellite's body axis, perpendicular to the camera optical axis, is set according to the maneuverability and pointing requirements, based on the body axis being in the direction of the set normal vector. The set normal vector direction is determined according to the tracking and aiming task, including:

[0007] Scenario 1: When the mobility meets the mission requirements and the antenna should communicate with the ground at all times, enter the communication maintenance mode. At this time, find the main axis with the largest angle between the camera optical axis and the antenna, and set its direction as the normal vector of the plane containing the tracking direction and the ground direction.

[0008] Scenario 2: When the maneuverability meets the mission requirements and the sail should generate electricity at all times, enter the energy conservation mode. At this time, select the body axis with the largest angle between the camera optical axis and the axis where the sail is located, and set its direction as the normal vector of the plane where the aiming direction and the sun direction are located.

[0009] Scenario 3: When the maneuverability can only meet the tracking and aiming requirements, enter the maneuver preservation mode. At this time, select the main axis with the largest angle with the orbital plane and set its direction as the normal vector of the plane where the satellite's relative trajectory is located.

[0010] Scenario 4: When the tracking stability requirement is the highest, enter the image preservation mode. In this mode, only the camera optical axis is set to point towards the target, and other axes are not controlled.

[0011] Furthermore, in the first scenario, let the Xr axis of the target attitude OXrYrZr point to the observed target, and Zr be the antenna direction; let the plane formed by Xr and the geocentric vector be the target-geocentric plane, then Yr is the normal vector of the target-geocentric plane; Zr is determined by the right-hand rule, and the Yr direction ensures that the angle between Zr and the geocentric vector is no greater than 90°; at this time, the nominal satellite attitude, while maintaining Xr pointing to the target, is conducive to data transmission between the data transmission antenna and the ground;

[0012] If it is necessary to ensure data transmission between the antenna and the ground while also considering energy or mobility, the angle to be selected... Rotate Yr and Zr around -Xr

[0013] When the angle between the central vector and Xr is greater than the protection angle AngPro but less than 180-AngPro, and the target pointing coordinate system is defined without singularities, then the target pointing attitude is:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023] in, Let Xr be the representation of Xr in an inertial frame. This represents the geocentric vector in an inertial frame. Zr is the angle between Zr and the target-geocentric plane; Zr is positive when its projection vector onto the plane is biased towards the -Yr direction. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame;

[0024] When the target leaves the singular region after passing the top, the roll angle input is limited. The actual attitude is: while maintaining the direction of pointing towards the target, the roll gradually changes from the initial roll angle to the changed theoretical roll angle.

[0025] Furthermore, the angular velocity of the rolling shaft varies depending on the satellite's maneuvering mode and capability. The angular velocity is 0.2° / s to 0.3° / s during wheel control and 0.3° / s to 0.35° / s during jet control.

[0026] Furthermore, in the second case, let the Xr axis of the target attitude OXrYrZr point to the observed target, and let Yr be perpendicular to the direction of the normal to the sail; let the plane formed by Xr and the solar vector be the target-sun plane, and let the plane normal vector be Yr; Zr is determined by the right-hand rule; the angle between Zr and the sunlight direction vector is no greater than 90°.

[0027] If we need to balance energy conservation with data transmission or mobility, then we should choose an angle. Rotate Yr and Zr around Xr

[0028] When the angle between the solar vector and the target pointing vector is greater than the protection angle AngPro and less than 180-AngPro, the target pointing coordinate system is defined without singularities, and the target pointing attitude is:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] in, Let Xr be the representation of Xr in an inertial frame. This represents the geocentric vector in an inertial frame. Zr is the angle between Zr and the target-geocentric plane; Zr is positive when its projection vector onto the plane is biased towards the -Yr direction. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame;

[0039] If the angle between the geocentric vector and Zr in the target-pointing coordinate system is greater than 90°, then rotate the target-pointing coordinate system 180° around Xr:

[0040]

[0041] like Then C ir =C ir *C x (π)

[0042] Where Coi is the transformation matrix of the orbital frame relative to the inertial frame, C x (π) is the state transition matrix when rotated 180° around the x-axis;

[0043] When the target leaves the singular region after passing the top, the roll angle input is limited. The actual attitude is: while maintaining the direction of pointing towards the target, the roll gradually changes from the initial roll angle to the changed theoretical roll angle.

[0044] Furthermore, the angular velocity of the rolling shaft varies depending on the satellite's maneuvering mode and capability. The angular velocity is 0.2° / s to 0.3° / s during wheel control and 0.3° / s to 0.35° / s during jet control.

[0045] Furthermore, in the third scenario, based on the target orbit prediction, the vectors pointing from the local satellite to the target at two different times are selected, and the normal vector of the plane formed by these two vectors is denoted as Yrbi; the plane formed by Yrbi and Xr is denoted as the target-inertial plane, and the vector in this plane that is perpendicular to Xr and has an angle with Yrbi not greater than 90° is defined as Yr; the Zr axis is determined by the right-hand rule.

[0046] If maintaining mobility requires consideration of energy or data transmission, then choose... Rotate Yr and Zr around -Xr

[0047] When the relative trajectories of the satellites are in the same plane, the nominal attitude of the satellites keeps Xr pointing to the target while making them basically maneuver around the Yb axis during the tracking process;

[0048] The target pointing attitude is the transformation matrix C between the inertial frame and the target pointing coordinate system. ir When Y rbi When the angle between the target pointing vector and the target pointing vector is less than the protection angle AngPro or greater than 180-AngPro, the target pointing coordinate system is defined as having a singular point; at this time, the satellite will maintain the target pointing attitude in actual on-orbit control, and the roll angle will be controlled by angular velocity damping.

[0049] When Y rbi When the angle between the target pointing vector and the target is greater than the protection angle AngPro but less than 180-AngPro, the nominal attitude is:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] in: Let Xr be the representation of Xr in an inertial frame, and Y be the representation of Xr in an inertial frame. rbi The inertial space unit vector set for remote control; To maintain the angle between Yr and the target-inertial plane, Yr is positive when its projection vector onto the plane is biased towards Zr; Zr is positive when its projection vector onto the plane is biased towards -Yr. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame.

[0061] Furthermore, in scenario four, after the satellite tracks the target according to mission requirements, when imaging the target, the roll angle is additionally set to be controlled by gyro integral, and the satellite does not rotate around Xr.

[0062] Furthermore, the transformation matrix C ir At the calculated singularity points, set the positions of other axes of the target attitude as needed.

[0063] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the following aiming-following attitude maneuver path planning method based on normal vectors.

[0064] A normal vector-based tracking attitude maneuver path planning device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the normal vector-based tracking attitude maneuver path planning method.

[0065] The advantages of this invention compared to the prior art are:

[0066] (1) This invention achieves the goal of maintaining the target attitude setting as much as possible when the antenna transmits data to the ground by applying the normal vector of the plane formed by the target pointing and the ground pointing;

[0067] (2) This invention achieves the goal of maintaining the target attitude setting of the solar panel normal to the sun as much as possible by applying the normal vector of the target pointing and the solar direction vector to form the plane normal vector;

[0068] (3) By setting the normal vector relative to the orbital plane, the present invention realizes the attitude trajectory setting of the target under the condition of limited maneuverability. Attached Figure Description

[0069] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0070] Figure 1 This is a schematic diagram of the target pointing coordinate system of the present invention, where phiIN = 0 (preserving data transmission). (Negative angle);

[0071] Figure 2 This is a schematic diagram of the coordinate system pointing to the target phiIN=1 (energy conservation) of the present invention (shown in the diagram). (Negative angle);

[0072] Figure 3 This is a schematic diagram of the target pointing coordinate system of the present invention with phiIN=2 (maintaining maneuverability) (in the diagram). (Negative angle);

[0073] Figure 4 This is a schematic diagram showing the angle between the camera and the Earth in Embodiment 1 of the present invention;

[0074] Figure 5This is a schematic diagram illustrating the target pointing accuracy and stability in Embodiment 1 of the present invention;

[0075] Figure 6 This is a schematic diagram of the angle between the normal of the solar panel and the sun in Embodiment 1 of the present invention;

[0076] Figure 7 This is a schematic diagram illustrating the camera tracking accuracy according to Embodiment 1 of the present invention;

[0077] Figure 8 This is a schematic diagram illustrating the stability of camera tracking of a target according to Embodiment 1 of the present invention;

[0078] Figure 9 This is a schematic diagram illustrating the target pointing accuracy in Embodiment 1 of the present invention;

[0079] Figure 10 This is a schematic diagram of the target stability in Embodiment 1 of the present invention;

[0080] Figure 11 This is a diagram showing the relative trajectory changes in Embodiment 2 of the present invention;

[0081] Figure 12 This is a schematic diagram illustrating the target pointing accuracy and stability in Embodiment 2 of the present invention. Detailed Implementation

[0082] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below with reference to 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 solutions of the present invention, rather than limitations on the technical solutions 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.

[0083] The following description, in conjunction with the accompanying drawings, provides a more detailed explanation of the tracking and aiming attitude maneuvering path planning method based on normal vectors provided by embodiments of the present invention. Specific implementation may include: at any moment during the tracking and aiming maneuver, setting the camera optical axis to align with the target; the direction of the body axis perpendicular to the camera optical axis is set according to maneuverability and pointing requirements, with the selected normal vector direction as the primary reference. This invention will provide normal vector selection and target attitude settings for four scenarios: data transmission preservation, energy preservation, maneuverability preservation, and imaging preservation. Data transmission preservation refers to minimizing the angle between the antenna pointing towards the Earth; energy preservation refers to minimizing the angle between the solar panel normal and the sunlight direction; maneuverability preservation refers to using maneuverability as much as possible in the target tracking direction; and imaging preservation refers to not rotating around the camera optical axis, but only setting the Euler angles of the other two axes.

[0084] Scenario 1: Data transmission protection condition, such as... Figure 1The target attitude is designed using the normal vectors of the plane containing the target and the Earth's orientation. Its characteristics are as follows: Without loss of generality, let the Xr axis of the target attitude OXrYrZr point towards the observed target; let the plane formed by Xr and the geocentric vector be the target-geocentric plane, then Yr is the normal vector of the target-geocentric plane. Zr is determined by the right-hand rule. The direction of Yr must ensure that the angle between Zr and the geocentric vector is no greater than 90°. This satellite nominal attitude, while maintaining Xr pointing towards the target, facilitates ground-pointing control of the data transmission antenna.

[0085] If it is necessary to maintain data transmission while also considering energy or mobility, a suitable angle can be selected. Rotate Yr and Zr around -Xr

[0086] When the angle between the center vector and the target pointing vector Xr is less than the protection angle AngPro (default 5°) or greater than 180-AngPro, the above target pointing coordinate system defines a singularity. In this case, the satellite will maintain the target pointing attitude during actual on-orbit control.

[0087] In summary, when the angle between the central vector and Xr is greater than the protection angle AngPro (default 5°) and less than 180-AngPro, the target pointing attitude (the transformation matrix C between the inertial frame and the target pointing coordinate system) is... ir The calculation is as follows:

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] in: Let Xr be the representation of Xr in an inertial frame. This is the representation of the geocentric vector in an inertial frame. The angle between Zr and the target-geocentric plane (Zr is positive when its projection vector onto the plane is biased towards the -Yr direction).

[0098] When the target passes overhead (i.e., Xr is parallel to the geocentric vector) and leaves the singular region, the roll angle will change rapidly. In order to ensure stable pointing, the satellite limits the roll angle input. The actual attitude is: while maintaining pointing towards the target, the roll angle gradually changes from the initial roll angle to the changed theoretical roll angle. The roll angular velocity during wheel control is slightly less than that during jet control, such as about 0.2° / s to 0.3° / s during wheel control and about 0.3° / s to 0.35° / s during jet control.

[0099] Scenario 2: Maintaining energy efficiency, such as... Figure 2 The target attitude is determined by the normal vectors of the planes containing the target and the sun. Its characteristics are as follows: Without loss of generality, let the Xr axis of the target attitude OXrYrZr point towards the observed target; let the plane formed by Xr and the sun vector be the target-sun plane, and its normal vector be Yr. Zr is determined by the right-hand rule, and the angle between Zr and the sunlight direction vector is no greater than 90°. This satellite nominal attitude, while maintaining Xr pointing towards the target, facilitates ground-pointing control of the data transmission antenna.

[0100] If it is necessary to ensure energy conservation while also considering data transmission or mobility, a suitable angle can be selected. Rotate Yr and Zr around Xr

[0101] When the angle between the solar vector and the target pointing vector is less than the protection angle AngPro (default 5°) or greater than 180-AngPro, the above target pointing coordinate system is defined as having a singularity. In this case, the satellite will maintain its target pointing attitude during actual on-orbit control.

[0102] Target pointing attitude calculation method:

[0103] When the angle between the solar vector and the target pointing vector is greater than the protection angle AngPro (default 5°) and less than 180-AngPro, the target pointing attitude (the transformation matrix C of the inertial attitude relative to the target attitude) is... ir The calculation is as follows:

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] If the angle between the geocentric vector and Zr in the target-pointing coordinate system is greater than 90°, then rotate the target-pointing coordinate system 180° around Xr:

[0114]

[0115] like Then C ir =C ir *C x (π)

[0116] in: Let Xr be the representation of Xr in an inertial frame. C is the representation of the unit vector pointing from the local star to the Sun in an inertial frame. oi Let C be the transformation matrix between the orbital frame and the inertial frame. oi (π) is the transformation matrix for rotating about the x-axis by π radians.

[0117] When phiIN=1 is set, the roll angle will change rapidly when the target passes overhead (i.e., Xr is parallel to the geocentric vector) and leaves the singular region. In order to ensure stable pointing, the satellite limits the roll angle input. The actual attitude is: while maintaining pointing to the target, the roll angle gradually changes from the initial roll angle to the changed theoretical roll angle. The roll angular velocity during wheel control is slightly less than the angular velocity during jet control.

[0118] Scenario 3: Maintain operational status, such as... Figure 3 The target attitude is set by placing the minimum inertia axis along the direction of the target's relative trajectory normal vector. Its characteristics are as follows: Based on the target's trajectory prediction, the vectors pointing from the local satellite to the target at two moments before and after the target's closest approach time are selected. The normal vector of the plane formed by these two vectors is denoted as Y. rbi To overcome the situation where the relative trajectories are not entirely within the same plane, let Y be... rbi The plane formed by Xr and Y is the target-inertia plane. Within this plane, elements perpendicular to Xr and Y... rbi Vectors with included angles not exceeding 90° are defined as Yr. The Zr axis is determined by the right-hand rule.

[0119] If maintaining mobility requires consideration of energy or data transmission, a suitable option can be selected. Rotate Yr and Zr around -Xr

[0120] When the relative trajectories of the satellites are basically in the same plane, the nominal attitude of the satellite can maintain Xr pointing towards the target while allowing it to maneuver around the Yb axis during the tracking process.

[0121] The target pointing attitude is the transformation matrix Cir between the inertial frame and the target pointing coordinate system. When Y... rbi When the angle between the target pointing vector and the target pointing vector is less than the protection angle AngPro (default 5°) or greater than 180-AngPro, the target pointing coordinate system defined in Section 3.5.3 has a singular point. In this case, the satellite will maintain the target pointing attitude during actual on-orbit control, and the roll angle will be controlled by angular velocity damping.

[0122] When Y rbi When the angle between the target pointing vector and the target pointing vector is greater than the protection angle AngPro (default 5°) and less than 180-AngPro, the nominal attitude (the transformation matrix C of the inertial attitude relative to the target pointing reference coordinate system) is... irs The calculation is as follows:

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133] in: Let Xr be the representation of Xr in the inertial frame, and Yrbi be the inertial space unit vector set by the remote control. To maintain the angle between Yr and the target-inertial plane (Yr is positive when its projection vector onto the plane is biased towards the Zr direction).

[0134] Case 4: Preserving the imaging condition, the camera optical axis direction is set only through gyroscope integration instead of using the normal vector.

[0135] Its characteristics are as follows:

[0136] After the satellite tracks the target according to the mission requirements as described above (phiIN=0 / 1 / 2), when imaging the target using the detailed camera, the roll angle can be additionally set using gyro integral control, i.e., remotely set phiIN=3 (to preserve imaging). In this mode, the satellite does not rotate around Xr, thereby improving the stability of the satellite around the Xr axis and ensuring imaging quality.

[0137] If the satellite's phiIN = 3 for an extended period, it will affect the pointing of Yr and Zr in inertial space. Therefore, it is generally recommended to use it only for short periods.

[0138] Example 1

[0139] Table 1 Example 1

[0140] Mean Anomaly at Epoch Target 1 Orbit Epoch Time 8 hours 42 minutes 16 seconds 8 hours 42 minutes 16 seconds Semi-major Axis a 42 hours 11 minutes 6 seconds 42 hours 16 minutes 6 seconds Eccentricity e 0.0002 0.0002 Orbital Inclination 0.001° 0.001° Longitude of Ascending Node 287.929° 287.929° Argument of Perigee 0° 0° Figure 4 345° 345.03°

[0141] For observation target 1, when the antenna is on the +Z axis, the data transmission control effect is as follows: Figure 6 , 5 As shown.

[0142] Observation target 1, assuming the vertical direction of the sail is +Z, the control effect while conserving energy is as follows: Figure 9 , 7 As shown in Figure 8.

[0143] The control result when maintaining the pointer is as follows Mean Anomaly at Epoch , 10 As shown.

[0144] Example 2

[0145] Table 2 Example 2

[0146] Target 2 Orbit Epoch Time 8 hours 42 minutes 16 seconds 8 hours 42 minutes 16 seconds Semi-major Axis a 4 hours 21 minutes 16 seconds 4 hours 21 minutes 16 seconds Eccentricity e Orbital Inclination 0.0006 0.0002 Longitude of Ascending Node 0.286° 7.001° Argument of Perigee 287.929° 287.929° Figure 11 0° 0° Figure 12 340° 340°

[0147] Calculation of relative path normal vector:

[0148] To increase the sharpness of captured images, a position with the smallest relative distance is typically chosen for tracking and aiming. This invention discusses examples where the line-of-sight angular velocity is large when the relative distance is small, such as... ​ As shown in the figure, x, y, and z are the three axes of the target star's orbital system, namely: the orbital center is at the target star, the x-axis points from the Earth's center to the target star, the y-axis points to the negative direction of the angular momentum of the target star's orbital plane, and the z-axis satisfies the right-hand rule. From the figure, we can see that: (1) the projection of the plane containing the relative trajectory onto the xoy plane is a straight line, so the degree to which the coplanarity assumption is satisfied actually depends on the degree of change of the xy plane of the orbital system; (2) at the position where the relative distance is the smallest, the projections of the relative vectors onto the xy axes of the orbital system both change sign, the rate of change of the z-axis projection changes sign, and the line-of-sight angular velocity is relatively large. The following text uses tmin to represent the moment when the relative distance is the smallest.

[0149] To estimate the normal vector of the plane containing the relative trajectory, this invention sets a time interval Δt, and uses r(t) to represent the relative position vector at time t. The normal vector is then:

[0150] Y rbi = r(tmin+Δt)×r(tmin-Δt)

[0151] In practice, we can also use the vectors r at the three times tmin-Δt, tmin, and tmin+Δt, calculate the normal vectors pairwise, and take their average as the normal vector Y. ri .

[0152] Considering that the orbital system will change slowly, r(t) and Y ri The position vector of the inertial frame is used in all calculations. The inertial frame vector Y needs to be given in the calculations below. ri In the expression Y of the observational system rbi =C rbi Y ri The control effect is as follows: ​ As shown.

[0153] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0154] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A tracking and aiming attitude maneuver path planning method based on normal vectors, characterized in that, At any moment during the tracking maneuver, the camera optical axis is set to align with the target. The direction of the satellite body axis perpendicular to the camera optical axis is set according to the maneuverability and pointing requirements, based on the direction of the body axis in the set normal vector direction. The setting of the normal vector direction is determined according to the tracking and aiming task, including: Scenario 1: When the mobility meets the mission requirements and the antenna should communicate with the ground at all times, enter the communication maintenance mode. At this time, find the main axis with the largest angle between the camera optical axis and the antenna, and set its direction as the normal vector of the plane containing the tracking direction and the ground direction. Scenario 2: When the maneuverability meets the mission requirements and the sail should generate electricity at all times, enter the energy conservation mode. At this time, select the body axis with the largest angle between the camera optical axis and the axis where the sail is located, and set its direction as the normal vector of the plane where the aiming direction and the sun direction are located. Scenario 3: When the maneuverability can only meet the tracking and aiming requirements, enter the maneuver preservation mode. At this time, select the main axis with the largest angle with the orbital plane and set its direction as the normal vector of the plane where the satellite's relative trajectory is located. Scenario 4: When the tracking stability requirement is the highest, enter the image preservation mode. In this mode, only the camera optical axis is set to point towards the target, and other axes are not controlled. In scenario one, let the Xr axis of the target attitude OXrYrZr point to the observed target, and Zr be the antenna direction; let the plane formed by Xr and the geocentric vector be the target-geocentric plane, then Yr is the normal vector of the target-geocentric plane; Zr is determined by the right-hand rule, and the direction of Yr ensures that the angle between Zr and the geocentric vector is no greater than 90°; at this time, the nominal attitude of the satellite, while maintaining Xr pointing to the target, is conducive to data transmission between the data transmission antenna and the ground; If it is necessary to ensure data transmission between the antenna and the ground while also considering energy or mobility, the angle to be selected... Rotate Yr and Zr around -Xr When the angle between the central vector and Xr is greater than the protection angle AngPro but less than 180-AngPro, and the target pointing coordinate system is defined without singularities, then the target pointing attitude is: in, Let Xr be the representation of Xr in an inertial frame. This represents the geocentric vector in an inertial frame. Zr is the angle between Zr and the target-geocentric plane; Zr is positive when its projection vector onto the plane is biased towards the -Yr direction. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame; When the target leaves the singular region after passing the top, the roll angle input is limited. The actual attitude is: while maintaining the direction of pointing towards the target, the roll gradually changes from the initial roll angle to the changed theoretical roll angle.

2. The tracking and aiming attitude maneuvering path planning method based on normal vectors according to claim 1, characterized in that, The angular velocity of the rolling axis varies depending on the satellite's maneuvering method and capability. The angular velocity is 0.2° / s to 0.3° / s during wheel control and 0.3° / s to 0.35° / s during jet control.

3. The tracking and aiming attitude maneuvering path planning method based on normal vectors according to claim 1, characterized in that, In the second scenario, let the Xr axis of the target attitude OXrYrZr point towards the observed target, and let Yr be perpendicular to the direction of the normal to the solar panel; let the plane formed by Xr and the solar vector be the target-solar plane, and let the plane normal vector be Yr; Zr is determined by the right-hand rule; the angle between Zr and the sunlight direction vector is no greater than 90°. If we need to balance energy conservation with data transmission or mobility, then we should choose an angle. Rotate Yr and Zr around Xr When the angle between the solar vector and the target pointing vector is greater than the protection angle AngPro and less than 180-AngPro, the target pointing coordinate system is defined without singularities, and the target pointing attitude is: in, Let Xr be the representation of Xr in an inertial frame. This represents the geocentric vector in an inertial frame. Zr is the angle between Zr and the target-geocentric plane; Zr is positive when its projection vector onto the plane is biased towards the -Yr direction. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame; If the angle between the geocentric vector and Zr in the target-pointing coordinate system is greater than 90°, then rotate the target-pointing coordinate system 180° around Xr: like Then C ir =C ir *C x (π) Among them, C oi Let C be the transformation matrix between the orbital frame and the inertial frame. x (π) is the state transition matrix when rotated 180° around the x-axis; When the target leaves the singular region after passing the top, the roll angle input is limited. The actual attitude is: while maintaining the direction of pointing towards the target, the roll gradually changes from the initial roll angle to the changed theoretical roll angle.

4. The tracking and aiming attitude maneuvering path planning method based on normal vectors according to claim 3, characterized in that, The angular velocity of the rolling axis varies depending on the satellite's maneuvering method and capability. The angular velocity is 0.2° / s to 0.3° / s during wheel control and 0.3° / s to 0.35° / s during jet control.

5. The tracking and aiming attitude maneuver path planning method based on normal vectors according to claim 1, characterized in that, In scenario three, based on the target orbit prediction, the vectors pointing from the local satellite to the target at two different times are selected, and the normal vector of the plane formed by these two vectors is denoted as Yrbi; the plane formed by Yrbi and Xr is denoted as the target-inertial plane, and the vector in this plane that is perpendicular to Xr and has an angle with Yrbi of no more than 90° is defined as Yr; the Zr axis is determined by the right-hand rule. If maintaining mobility requires consideration of energy or data transmission, then choose... Rotate Yr and Zr around -Xr When the relative trajectories of the satellites are in the same plane, the nominal attitude of the satellites maintains that Xr points to the target while making them basically maneuver around the Yb axis during the tracking process; The target pointing attitude is the transformation matrix C between the inertial frame and the target pointing coordinate system. ir When Y rbi When the angle between the target pointing vector and the target pointing vector is less than the protection angle AngPro or greater than 180-AngPro, the target pointing coordinate system is defined as having a singular point; at this time, the satellite will maintain the target pointing attitude in actual on-orbit control, and the roll angle will be controlled by angular velocity damping. When Y rbi When the angle between the target pointing vector and the target is greater than the protection angle AngPro but less than 180-AngPro, the nominal attitude is: in: Let Xr be the representation of Xr in an inertial frame, and Y be the representation of Xr in an inertial frame. rbi The inertial space unit vector set for remote control; To maintain the angle between Yr and the target-inertial plane, Yr is positive when its projection vector onto the plane is biased towards Zr; Zr is positive when its projection vector onto the plane is biased towards -Yr. The target is pointed to, which is also the unit vector of Xr. for The unit vector of Yr at time , for The unit vector of Zr, C ir0 for The transformation matrix C from the reference target attitude to the J2000 inertial frame. xbias For rotation about the -Xr axis The corresponding coordinate transformation matrix, and Considering respectively The three-axis direction vectors of the target's attitude at that time. C ir0 The transpose of C ir The attitude transformation matrix from the reference attitude to the J2000 inertial frame.

6. A tracking and aiming attitude maneuvering path planning method based on normal vectors according to any one of claims 2 to 5, characterized in that, In scenario four, after the satellite tracks the target according to mission requirements, when imaging the target, the roll angle is additionally set to be controlled by gyro integral, and the satellite does not rotate around Xr.

7. The tracking and aiming attitude maneuvering path planning method based on normal vectors according to claim 1, characterized in that, The transformation matrix C ir At the calculated singularity points, set the positions of other axes of the target attitude as needed.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 5.

9. A tracking and aiming attitude maneuvering path planning device based on normal vectors, 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, it implements the steps of the method as described in any one of claims 1 to 5.

Images