AC-axis orthogonal ACE seat frame coordinate conversion method

Abstract

The invention relates to an AC-axis orthogonal ACE seat frame coordinate conversion method which is mainly applied to real-time satellite tracking of a shipborne antenna. Aiming at the problem of communication signal interruption caused by seat frame form switching when the pitch angle of the traditional ACE seat frame is rapidly changed in a large range, the invention provides a brand-new coordinate conversion method. According to the method, attitude information of a carrier is acquired in real time, a deck angle calculation formula of orientation, pitching and a cross axis is deduced based on an ACE seat frame structure with an orthogonal AC axis, so that the cross axis participates in tracking in the whole process, and seat frame form switching in the tracking process is avoided. The method can effectively adapt to the scene that the pitch angle changes rapidly in low-orbit satellite tracking, continuous and stable communication is ensured, the tracking performance of the three-axis ACE seat frame antenna is improved, and the application range of the three-axis ACE seat frame antenna is widened.

Description

Technical Field

[0001] The field of this invention is electronic information technology, specifically a coordinate transformation method for an AC-axis orthogonal ACE mount. Background Technology

[0002] In the current satellite communication environment, given the large changes in elevation angle and short time intervals, the communication antenna needs to calculate the antenna's pointing angle to the satellite in real time based on the target satellite information and the changes in position and attitude during the carrier's movement, and control the antenna to quickly align with the incoming satellite to track it, thus ensuring the transmission of communication signals.

[0003] Traditional ACE mount shipborne antennas employ a tracking method where the A-axis and E-axis track at low elevation angles while the C-axis remains at zero position, and the C-axis participates in tracking in a cross-tracking manner at high elevation angles. Therefore, switching from AE-axis tracking to ACE-axis tracking causes sudden signal interruptions. Three-axis ACE mount antennas using traditional methods cannot meet the tracking and communication requirements of rapid elevation changes and short tracking times.

[0004] Specific problems currently existing: When tracking satellites, the elevation angle varies greatly. The traditional ACE tracking target coordinate transformation method will cause communication discontinuity when converting AE axis tracking at low elevation angles to ACE axis tracking at high elevation angles. Summary of the Invention

[0005] This invention addresses the issue that when traditional ACE mount antennas track satellites, the large range of elevation angle changes within a short period of time causes a sudden drop in signal due to mount configuration switching. It proposes a coordinate transformation method suitable for ACE mounts with orthogonal A-axis and C-axis.

[0006] The specific technical solution adopted in this invention is as follows: A method for coordinate transformation of an ACE mount under orthogonal AC axis, specifically including the following process: Step 1: Calculate the actual geographic location based on the target information; Step 2: Communicate with the inertial navigation system and obtain the attitude information of the carrier in real time; the attitude information includes latitude and longitude, heading, roll and pitch. Step 3: Calculate the antenna's pointing angle towards the deck in real time based on the changes in position and attitude of the carrier during its movement; ; ; ; in: A d The lower target deck angle is given by the inertial navigation deck coordinate system. This is the geodetic azimuth of the antenna pointing towards the target. p The pitch angle given by the inertial navigation system for antenna guidance. r The roll angle given by the antenna-guided inertial navigation system. k The heading angle given by the inertial navigation system guided by the antenna. E d The pitch angle of the target deck in the inertial navigation deck coordinate system; Step 4: Calculate the geographic angle based on the direction the antenna points towards the deck and the changes in position and attitude of the carrier during its movement. ; in, This is the geodetic azimuth of the antenna pointing towards the target. The elevation angle of the antenna pointing towards the target. k The heading angle given by the inertial navigation system guided by the antenna. p The pitch angle given by the inertial navigation system for antenna guidance. r The roll angle given by the antenna-guided inertial navigation system. A d The lower target deck angle is given by the inertial navigation deck coordinate system. E d The pitch angle of the target deck in the inertial navigation deck coordinate system. C d The target deck angle of the ACE mount in the inertial navigation deck coordinate system is zero in azimuth and 90 degrees in elevation. When the antenna is pointing towards the bow, a deviation to starboard is positive. x and y are temporary variables. Step 5: Based on the comparison between the calculated geographic angle and the target geographic angle, control the servo loop parameters to make them reasonable.

[0007] Compared with the prior art, the present invention has the following beneficial effects: This invention features a cross-axis antenna that participates in tracking throughout the entire process, preventing signal drop caused by changes in mount configuration due to elevation angle variations. It is suitable for tracking low-Earth orbit satellites where elevation angles change significantly within a short period, greatly expanding the application scenarios of the tri-axis ACE mount antenna with orthogonal AC axes and meeting both tracking and communication requirements. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the shaft system. Detailed Implementation

[0009] However, the scope of protection of this invention is not limited to the described embodiments.

[0010] This embodiment redesigns the azimuth, pitch, and crosshair pointing strategies for the ACE mount with the AC axis orthogonal. The attitude angles k (heading angle), p (pitch angle), and r (roll angle) characterize the carrier's heading and tail lines. The geodetic coordinate system is defined according to the right-hand rule, with the positive directions of the x, y, and z axes pointing north, sky, and east, respectively. See details... Figure 1 .

[0011] The conversion is completed in two steps: First, the geodetic coordinate system is transformed into the carrier deck coordinate system by rotating the carrier attitude angles k (heading angle), p (pitch angle), and r (roll angle) sequentially along the y, z, and x axes. Then, the azimuth deck angle is rotated along the y-axis and the β-angle is rotated along the z-axis to the C-axis of the carrier. The angle between the projection of the C-axis onto the horizontal plane and true north is equal to the target geodetic angle, thus establishing an equation to calculate the azimuth target deck angle.

[0012] Secondly, based on the calculated azimuth deck angle, the roll and pitch angles of the cross axis are solved, making the cross target deck angle equal to the negative roll angle of the cross axis, and the pitch target deck angle equal to the pitch target ground angle minus the pitch angle of the cross axis. This completes the derivation of the calculation formulas for the pitch and cross target deck angles. By simultaneously involving the azimuth, pitch, and cross axes in attitude angle isolation, the antenna can meet tracking and communication requirements even with large carrier attitudes. Furthermore, it resolves the signal interruption caused by switching from the AE axis to the ACE axis during ACE mount tracking. The specific calculation process for the tracking coordinate transformation method is as follows: Step 1: Calculate the actual geographic location based on the target information; Step 2: Communicate with the inertial navigation system to obtain the carrier's attitude information in real time; the attitude information includes latitude and longitude, heading, roll and pitch. Step 3: Calculate the antenna's pointing angle towards the deck in real time based on the changes in position and attitude of the carrier during its movement. ; ; ; Step 4: Calculate the geographic angle based on the direction of the antenna on the deck and the changes in position and attitude of the carrier during its movement. The calculation yields: ; in, This is the geodetic azimuth of the antenna pointing towards the target. The elevation angle of the antenna pointing towards the target. k The heading angle given by the inertial navigation system guided by the antenna. p The pitch angle given by the inertial navigation system for antenna guidance. r The roll angle given by the antenna-guided inertial navigation system.A d The lower target deck angle is given by the inertial navigation deck coordinate system. E d The pitch angle of the target deck in the inertial navigation deck coordinate system. C d The target deck angle of the ACE mount in the inertial navigation deck coordinate system is zero in azimuth and 90 degrees in pitch. When the antenna is pointing towards the bow, the deviation to the starboard side is positive. x and y are temporary variables.

[0013] Step 5: Based on the comparison between the calculated geographic angle and the target geographic angle, control the servo loop parameters to make them reasonable.

Claims

1. A method for coordinate transformation of an ACE mount with orthogonal AC axis, characterized in that, Specifically, the process includes the following: Step 1: Calculate the actual geographic location based on the target information; Step 2: Communicate with the inertial navigation system and obtain the attitude information of the carrier in real time; the attitude information includes latitude and longitude, heading, roll and pitch. Step 3: Calculate the antenna's pointing angle towards the deck in real time based on the changes in position and attitude of the carrier during its movement; ； ； ； in: A d The lower target deck angle is given by the inertial navigation deck coordinate system. This is the geodetic azimuth of the antenna pointing towards the target. p The pitch angle given by the inertial navigation system for antenna guidance. r The roll angle given by the antenna-guided inertial navigation system. k The heading angle given by the inertial navigation system guided by the antenna. E d The pitch angle of the target deck in the inertial navigation deck coordinate system; Step 4: Calculate the geographic angle based on the direction the antenna points towards the deck and the changes in position and attitude of the carrier during its movement. ； in, This is the geodetic azimuth of the antenna pointing towards the target. The elevation angle of the antenna pointing towards the target. k The heading angle given by the inertial navigation system guided by the antenna. p The pitch angle given by the inertial navigation system for antenna guidance. r The roll angle given by the antenna-guided inertial navigation system. A d The lower target deck angle is given by the inertial navigation deck coordinate system. E d The pitch angle of the target deck in the inertial navigation deck coordinate system. C d The target deck angle of the ACE mount in the inertial navigation deck coordinate system is zero in azimuth and 90 degrees in elevation. When the antenna is pointing towards the bow, a deviation to starboard is positive. x and y are temporary variables. Step 5: Based on the comparison between the calculated geographic angle and the target geographic angle, control the servo loop parameters to make them reasonable.

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