A pointing coordinate transformation method for a spaceborne dual-offset reflector antenna

Abstract

This invention discloses a pointing coordinate transformation method for a spaceborne dual-offset reflector antenna, belonging to the field of space measurement. The method first calculates an installation parameter matrix characterizing the transformation relationship between the antenna installation reference coordinate system and the satellite reference coordinate system; secondly, it measures the antenna's offset angle under the antenna's zero-position attitude and constructs an electrical geometric parameter matrix characterizing its inherent structural transformation; then, it obtains the desired pointing coordinates of the antenna's electrical axis in the satellite coordinate system, expressed in azimuth and elevation angles; finally, based on azimuth, elevation, and , it solves for the principal axis rotation angle and the secondary axis rotation angle used to drive the antenna pointing mechanism through coordinate transformation. This invention solves the pointing coordinate transformation problem caused by the non-orthogonal parallelism between the dual-offset antenna rotation axis and the satellite coordinate axis, ensuring high-precision pointing of the antenna in orbit. It has been verified through anechoic chamber testing and can be extended to other antenna systems containing dual-axis rotation mechanisms.

Description

Technical Field

[0001] This invention belongs to the field of space measurement technology, specifically relating to a method for measuring and calculating the pointing of a spaceborne antenna based on coordinate transformation, and more specifically to a pointing coordinate transformation method for a spaceborne dual-offset reflector antenna. Background Technology

[0002] Spaceborne dual-offset reflector antennas are widely used in space-to-ground communications due to their high gain, high transmission efficiency, and high reliability. However, the pointing mechanism of this type of antenna differs from traditional AE or XY mounts; its actual rotation axis is neither perpendicular nor parallel to the satellite coordinate axes. This makes it impossible for existing pointing coordinate transformation methods to accurately calculate the principal and secondary axis rotation angles of the antenna's actual pointing mechanism using the azimuth and elevation angles in the satellite coordinate system. Currently, there is no publicly available information providing an effective calculation method for the pointing coordinates of dual-offset reflector antennas, which limits the realization of high-precision on-orbit pointing and scanning tracking functions. Summary of the Invention

[0003] The purpose of this invention is to solve the problem that existing pointing coordinate transformation methods cannot accurately calculate the primary and secondary axis rotation angles of the actual pointing mechanism of a dual-offset reflector antenna using pointing coordinates in a satellite coordinate system. Instead, this invention proposes a method to obtain the pointing coordinates (primary and secondary axis rotation angles) of a dual-offset reflector antenna by performing coordinate transformation using the antenna's installation parameters, electrical geometric parameters, and azimuth and elevation angles in a satellite coordinate system.

[0004] To achieve the above objectives, the technical solution provided by this invention is:

[0005] A method for transforming the pointing coordinates of a spaceborne dual-offset reflector antenna is provided, comprising the following steps:

[0006] Step 1: Obtain the antenna installation parameter matrix The installation parameter matrix is ​​used to characterize the transformation relationship between the antenna installation reference coordinate system and the satellite reference coordinate system;

[0007] Step 2: Obtain the antenna's electrical geometric parameter matrix. The electrical geometry parameter matrix is ​​based on the antenna offset angle. A structure is constructed to characterize the rotational transformation relationship between the antenna rotation axis coordinate system and the antenna mounting reference coordinate system when the antenna electrical axis is in the same direction as the specified axis of the antenna mounting reference coordinate system in the zero-position attitude.

[0008] Step 3: Obtain the desired pointing coordinates of the antenna's electrical axis in the satellite reference coordinate system. The desired pointing coordinates include the azimuth angle. and pitch angle ;

[0009] Step 4, based on the installation parameter matrix Electrical geometric parameter matrix Azimuth and pitch angle The principal axis rotation angle used to drive the antenna pointing mechanism is calculated through coordinate transformation. and secondary axis rotation angle , which serves as the pointing coordinate in the antenna rotation axis coordinate system.

[0010] Furthermore, step 1 specifically includes:

[0011] Step 101: Establish a satellite reference coordinate system by measuring the satellite's physical reference surface. ;

[0012] Step 102: Establish the antenna installation reference coordinate system by measuring the physical reference plane of the antenna. ;

[0013] Step 103, Calculate the installation parameter matrix Its expression is:

[0014]

[0015] In the formula, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle.

[0016] Furthermore, step 101 specifically includes: measuring the satellite's... datum plane and Reference planes, with any measurement point on these two reference planes as the origin. And establish based on its normal direction shaft and The axis is then determined using the right-hand rule. axis.

[0017] Further, step 102 specifically includes: measuring the existing [data / values] on the antenna mounting flange or frame. Mounting reference plane and Install reference planes, and use any measuring point on these two reference planes as the origin. And establish based on its normal direction shaft and The axis is then determined using the right-hand rule. axis.

[0018] Furthermore, step 2 specifically includes:

[0019] In the antenna electrical axis and antenna mounting reference coordinate system Under the zero-position attitude with the same axis orientation, measure the offset angle of the antenna. Offset angle The antenna principal axis and the antenna mounting reference coordinate system The angle between the axes;

[0020] Based on the offset angle The electrical geometry parameter matrix is ​​calculated using the following expression:

[0021] .

[0022] Furthermore, the antenna offset angle is measured. Specifically, this includes: measuring the spatial orientation of the antenna principal axis when the antenna's electrical axis is in its zero-position attitude, and calculating the relationship between the antenna principal axis and the antenna mounting reference coordinate system. The angle between the axes is used as the offset angle.

[0023] Furthermore, in step 3, the desired pointing coordinates are calculated based on the satellite orbital parameters and the ground location of the communication target.

[0024] Furthermore, in step 4, the principal face axis rotation angle is calculated by solving the following equation. and secondary axis rotation angle :

[0025]

[0026] In the formula, This is the initial pointing vector of the antenna's electrical axis in the satellite's reference coordinate system.

[0027] The advantages of this invention are:

[0028] 1. The pointing coordinate transformation method for a spaceborne dual-offset reflector antenna provided by this invention establishes a complete and rigorous mathematical transformation model by introducing and accurately measuring the antenna's installation parameter matrix and electrical geometric parameter matrix. This model successfully transforms the azimuth and elevation angles in the satellite coordinate system into the actual rotation angles of the primary and secondary axes of the antenna pointing mechanism. This method effectively solves the pointing calculation problem caused by the special mechanical structure of the dual-offset antenna and the non-orthogonal parallelism between the rotation axis and the satellite coordinate axis. It achieves high precision and high reliability in on-orbit pointing of the antenna, ensuring that the antenna's electrical axis is always accurately aligned with the ground gateway station. This guarantees the stable maintenance of high-intensity signals and high data transmission rates in the communication link, significantly improving the quality of satellite-to-ground communication.

[0029] 2. This method does not rely on complex real-time calibration; precise pointing can be achieved through model calculations, demonstrating strong engineering applicability and repeatability. Furthermore, the process and core concepts involved in this coordinate transformation method possess good versatility and can be extended to other spaceborne antenna systems containing similar dual-axis rotation mechanisms, providing reliable technical support for precise on-orbit pointing control of various high-performance antennas. Attached Figure Description

[0030] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

[0031] Figure 1 This is a flowchart illustrating the pointing coordinate transformation method for the spaceborne dual-offset reflector antenna of the present invention.

[0032] Figure 2 This is a schematic diagram of the antenna installation parameter measurement process in this invention;

[0033] Figure 3 This is a schematic diagram of the antenna electrical geometric parameter measurement process in this invention;

[0034] Figure 4 This is a schematic diagram of the pointing coordinate representation in the satellite coordinate system of this invention;

[0035] Figure 5 This is a schematic diagram of the pointing coordinates in the antenna rotation axis coordinate system of this invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0037] The pointing coordinate transformation method for spaceborne dual-offset reflector antennas provided by this invention establishes a complete and rigorous mathematical transformation model, which can effectively solve the pointing calculation problem caused by the special mechanical structure of dual-offset antennas and the non-orthogonal parallelism between the rotation axis and the satellite coordinate axis.

[0038] Reference Figure 1 The pointing coordinate transformation method of the spaceborne dual-offset reflector antenna, as an exemplary embodiment of the present invention, includes four core steps: obtaining the antenna installation parameter matrix, obtaining the antenna electrical geometric parameter matrix, obtaining the desired pointing coordinates of the antenna electrical axis in the satellite coordinate system, and calculating the pointing coordinates in the antenna rotation axis coordinate system.

[0039] First, perform step S1: Obtain the antenna installation parameter matrix. This matrix is ​​used to characterize the transformation relationship between the antenna installation reference coordinate system and the satellite reference coordinate system. The detailed process for this step is as follows: Figure 2 As shown, a satellite reference coordinate system is first established by measuring the satellite's physical reference surface. Using precision measuring equipment, such as laser trackers, to measure the existing features on the satellite itself. datum plane and Reference planes, with any measurement point on these two reference planes as the origin. And establish based on the normal directions of the two reference planes. shaft and The axis is then determined using the right-hand rule. This establishes a complete satellite reference coordinate system. Subsequently, an antenna installation reference coordinate system is established by measuring the antenna's physical reference plane. Similarly, through precise measurements, the existing measurements on the antenna mounting flange or frame are taken. Mounting reference plane and Install reference planes, and use any measuring point on these two reference planes as the origin. And establish based on its normal direction shaft and The axis is then determined using the right-hand rule. Axis. Finally, calculate the installation parameter matrix. This matrix is ​​a 3x3 direction cosine matrix, where each element is the cosine of the angle between each axis of the antenna installation reference coordinate system and each axis of the satellite reference coordinate system. The specific expression is as follows:

[0040]

[0041] In the formula, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle. This matrix accurately represents the antenna's installation attitude on the satellite.

[0042] Next, proceed to step S2: obtain the electrical geometric parameter matrix of the antenna. This matrix is ​​based on the offset angle of the dual-offset reflector antenna. This process constructs a model to characterize the rotational transformation relationship between the antenna rotation axis coordinate system and the antenna mounting reference coordinate system in a zero-position attitude where the antenna's electrical axis is aligned with a specified axis of the antenna mounting reference coordinate system. The detailed procedure for this step is as follows: Figure 3 As shown, the core issue is determining the inherent coordinate transformations caused by the antenna's own mechanical structure. Here, we first define the antenna rotation axis coordinate system. The coordinate system takes the intersection of the two rotating axes of the antenna pointing mechanism as its origin. With the axial direction of the antenna principal plane axis as The axis, the axial direction of the antenna subplane axis is The axis is determined by the right-hand rule. In specific implementation, the antenna is first driven to its zero-position attitude. In this embodiment, the zero-position attitude is the orientation of the antenna's electrical axis relative to the antenna coordinate axis (i.e., the antenna mounting reference coordinate system). The antenna is in the same orientation as the axis. Under this zero-position attitude, the key electrical geometric parameter of the antenna—the offset angle—is measured. The offset angle In this embodiment, it specifically refers to the antenna principal plane axis (i.e., the antenna rotation axis coordinate system). (axis) and antenna coordinate axes (i.e., the antenna mounting reference coordinate system) The spatial angle between the antenna principal axis and the antenna coordinate axes. High-precision measuring equipment (such as a laser tracker or theodolite) can be used to measure the spatial direction vector of the antenna principal axis, and then the angle between the antenna principal axis and the antenna coordinate axes can be calculated. This angle is the required offset angle. Finally, based on the measured offset angle... Calculate the electrical geometric parameter matrix The specific expression is as follows:

[0043]

[0044] This matrix precisely characterizes the antenna rotation axis coordinate system under the antenna's null orientation. Antenna installation reference coordinate system The fixed rotational transformation relationship between them. This relationship is uniquely determined by the physical structure of the dual-bias antenna and is the key basis for subsequent coordinate transformations.

[0045] Then, perform step S3: obtain the desired pointing coordinates of the antenna's electrical axis in the satellite reference coordinate system. These pointing coordinates are represented as follows... Figure 4 As shown, azimuth angle is used. and pitch angle To define. During on-orbit operation, this set of coordinates ( , The angles are calculated by the satellite's control system based on real-time satellite orbit parameters and the location of the ground target requiring communication. This calculation process is a well-known and mature technology in the field, and will not be described in detail here. This set of angles represents the target direction that the antenna's electrical axis needs to point to in the satellite coordinate system.

[0046] Finally, perform step S4: calculate the pointing coordinates in the antenna rotation axis coordinate system. The pointing coordinates (i.e., the drive angle) in the antenna rotation axis coordinate system are defined as follows: Figure 5 As shown, including the main face axis rotation angle and secondary axis rotation angle In the specific calculation, the results obtained from the aforementioned steps are... , , and Substitute the following equations to solve:

[0047]

[0048] In the formula, the two rotation matrices on the left side of the equation correspond to the rotation angles of the secondary axis, respectively. (Coordinate system around the antenna axis) (axis rotation) and principal plane axis rotation angle (Coordinate system around the antenna axis) (axis rotation), the two rotation matrices on the right correspond to the azimuth angles in the satellite reference coordinate system, respectively. (around the satellite reference coordinate system) (axis rotation) and pitch angle (around the satellite reference coordinate system) (axis rotation) and These are the inverse matrices of the electrical geometry parameter matrix and the installation parameter matrix, respectively. Based on the initial pointing vector of the antenna's electrical axis in the satellite reference coordinate system during the satellite-to-ground pointing mission. This allows for the calculation of the precise principal axis rotation angle required to drive the antenna pointing mechanism. and secondary axis rotation angle .

[0049] To verify the accuracy and reliability of the method of this invention, a calculation verification was performed using a dual-biased parabolic antenna as an example. The installation parameter matrix of the antenna was obtained through actual measurement. and electrical geometric parameter matrix They are as follows:

[0050] ,

[0051] Based on the on-orbit pointing requirements, the desired pointing coordinates in the given satellite reference coordinate system are the azimuth angles. Pitch angle The initial pointing vector is Substituting the above parameters into the matrix equation of step S4 and solving it, the required principal plane axis rotation angle of the antenna pointing mechanism is calculated. Secondary axis rotation angle .

[0052] The calculation result was used as a drive command input to the antenna pointing mechanism, and the actual pointing of the antenna's electrical axis was measured in an anechoic chamber using a far-field testing system. The measurement results show that the actual pointing of the antenna's electrical axis is consistent with the expected pointing (…). , The deviation between the two is less than 0.1°, which meets the accuracy requirements for on-orbit tracking of high-gain antennas. This verification result fully demonstrates the correctness and high precision of the coordinate transformation method proposed in this invention, and can effectively ensure that the dual-offset reflector antenna can achieve stable tracking and communication with ground gateway stations on orbit.

[0053] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A method for pointing coordinate transformation of a space-borne dual- bias reflector antenna, characterized in that, The method comprises the following steps: Step 1, obtaining an installation parameter matrix of the antenna , the installation parameter matrix being used to represent a transformation relationship between an antenna installation reference coordinate system and a satellite reference coordinate system; Step 2: Obtain the antenna's electrical geometric parameter matrix. The electrical geometry parameter matrix is ​​based on the antenna offset angle. A framework is constructed to characterize the rotational transformation relationship between the antenna rotation axis coordinate system and the antenna mounting reference coordinate system under the zero-position attitude where the antenna electrical axis is in the same direction as the specified axis of the antenna mounting reference coordinate system. Specifically, this includes: In the antenna electrical axis and antenna mounting reference coordinate system of Under the zero-position attitude with the same axis orientation, measure the offset angle of the antenna. The offset angle Antenna principal axis and antenna mounting reference coordinate system of The angle between the axes; according to the offset angle The electrical geometry parameter matrix is ​​calculated, and its expression is as follows: ； Step 3, obtaining desired pointing coordinates of the antenna electrical axis in the satellite reference coordinate system, the desired pointing coordinates comprising an azimuth angle and an elevation angle ; Step 4, based on the installation parameter matrix The electrical geometric parameter matrix The azimuth angle and the pitch angle The principal axis rotation angle used to drive the antenna pointing mechanism is calculated through coordinate transformation. and secondary axis rotation angle , serving as the pointing coordinate in the antenna rotation axis coordinate system; wherein, the principal plane axis rotation angle and the rotation angle of the secondary surface axis Calculate by solving the following equation: In the formula, is the initial pointing vector of the antenna electrical axis in the satellite reference coordinate system.

2. The pointing coordinate transformation method of claim 1, wherein, Step 1 specifically comprises: Step 101, establishing a satellite reference coordinate system by measuring the physical reference plane of the satellite ; Step 102, establishing an antenna installation reference coordinate system by measuring the physical reference plane of the antenna ; Step 103, calculating the installation parameter matrix The expression is: In the formula, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle, Representative axis With axis The included angle.

3. The pointing coordinate transformation method of claim 2, wherein, Step 101 specifically includes: measuring the satellite's... datum plane and Reference planes, with any measurement point on these two reference planes as the origin. And establish based on its normal direction shaft and The axis is then determined using the right-hand rule. axis.

4. The pointing coordinate transformation method of claim 2, wherein, Step 102 specifically includes: measuring the existing antenna mounting flange or frame. Mounting reference plane and Install reference planes, and use any measuring point on these two reference planes as the origin. And establish based on its normal direction shaft and The axis is then determined using the right-hand rule. axis.

5. The pointing coordinate transformation method of claim 1 or 2, wherein, Measuring the offset angle of the antenna Specifically, this includes: measuring the spatial direction of the antenna principal axis when the antenna's electrical axis is in the zero-position attitude, and calculating the relationship between the antenna principal axis and the antenna mounting reference coordinate system. The angle between the axes is referred to as the offset angle.

6. The pointing coordinate transformation method according to claim 1 or 2, characterized in that, In step 3, the expected pointing coordinates are calculated according to satellite orbit parameters and the ground position of the communication target.

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