Iterative calculation method and system for pointing to space target in strapdown mode

Abstract

The application discloses a kind of space target pointing iterative calculation method and system of strapdown, belong to communication and measurement control technical field.The application is installed on the azimuth rotating platform of horizontal tracking frame by heading angle output angle as azimuth feedback information by heading angle output angle as azimuth feedback information, combined with the geographical pointing angle of space target, the theoretical heading angle when horizontal tracking frame points to space target is calculated using iterative method, and the corresponding heading angle correction method is provided.The application is installed on the azimuth rotating platform of horizontal tracking frame by the method that heading angle output angle as azimuth feedback information is output as feedback information, avoids the azimuth axis angle initialization process, effectively reduces the start-up time of horizontal tracking frame, with the advantages of no need to increase additional hardware, simple implementation, wide application range.

Description

Technical Field

[0001] This invention relates to the field of communication and measurement and control technology, specifically to a strapdown-type iterative calculation method and system for pointing spatial targets. Background Technology

[0002] Ground-based tracking frames typically employ a two-axis structure, including azimuth and pitch degrees of freedom. This is used to overcome the directional disturbances caused by the carrier's motion on its load and to control the load's orientation towards the space target. They are widely used in satellite communication, UAV telemetry and control, and photoelectric tracking. In existing technologies, the azimuth axis of ground-based tracking frames generally uses an incremental encoder. At startup, the azimuth axis is first driven to rotate to the corresponding zero-pointing mechanism to initialize the angle. Simultaneously, an attitude measurement module is installed on the tracking frame base to sense the angular motion input of the mounting platform. After coordinate transformation, this input is compensated to the azimuth and pitch axes of the tracking frame to maintain stable pointing towards the space target. This method has the following shortcomings:

[0003] 1) The need for a standard component mechanism increases hardware costs and system complexity;

[0004] 2) Azimuth axis initialization is required when starting work, which increases startup time;

[0005] 3) The attitude measurement module is installed on the base of the tracking frame, which requires precise calibration of the non-levelness of the large disk of the azimuth rotation platform, increasing the difficulty of debugging. Summary of the Invention

[0006] In view of this, the present invention discloses a strapdown-type spatial target pointing iterative calculation method and system. The present invention avoids the azimuth axis initialization process by using the output of the attitude measurement module installed on the azimuth rotation platform of the horizon-mounted tracking frame as feedback information, effectively reducing the startup time of the horizon-mounted tracking frame. It has the advantages of requiring no additional hardware, being simple to implement, and having a wide range of applications.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A strapdown-based iterative calculation method for pointing to space targets includes the following steps:

[0009] Step 1: Obtain the attitude information output by the attitude measurement module in real time, including heading ψ, roll γ, and pitch θ;

[0010] Step 2: Based on the position information of the space target and the position information of the ground-based tracking frame, calculate the theoretical pointing angle of the ground-based tracking frame relative to the space target, including the theoretical azimuth angle A. d And pitch theory angle E d ;

[0011] Step 3: Based on the theoretical pointing angle and attitude information, calculate in real time the deck pointing angle of the horizontal tracking frame aligned with the space target, including the target deck angle ψ. j and pitch target deck angle E j Drive the tracking frame to rotate to the deck pointing angle;

[0012] Step 4: After the horizontal tracking frame is aligned with the space target, the heading ψ of the attitude measurement module is corrected.

[0013] Furthermore, in step 3, the heading target deck angle ψ j and pitch target deck angle E j The calculation is performed using an iterative method, specifically as follows:

[0014] (301) Establish the horizontal tracking frame pointing coordinate system Ox a y a z a Its coordinate axis x a Parallel to the horizontal plane and pointing to the right, y a The pitch axis, perpendicular to the ground-based tracking frame, points forward, z a With x a y a Construct a right-handed coordinate system; establish the azimuth turntable coordinate system Ox for the horizontal tracking frame. b y b z b Its coordinate axis x b The pitch axis, parallel to the ground-based tracking frame, points to the right, z b The azimuth axis, parallel to the horizontal tracking frame, points upwards, y b With x b z b Construct a right-handed coordinate system;

[0015] (302) Construct the geographic coordinate system Ox n y n z n To Ox a y a z a coordinate transformation matrix

[0016]

[0017] In the formula R x (α), R y (α), R z (α) is a single-axis rotation matrix, and

[0018]

[0019] (303) Initialize the heading target deck angle ψ j=0;

[0020] (304) Constructing the geographic coordinate system Ox n y n z n To Ox b y b z b coordinate transformation matrix

[0021]

[0022] (305) Construct Ox b y b z b To Ox j y j z j coordinate transformation matrix

[0023]

[0024] (306) Calculate the target deck angle ψ of the heading j and pitch target deck angle E j :

[0025]

[0026]

[0027] Where C[i][j] represents the element in the i-th row and j-th column of matrix C;

[0028] (307) Calculate the heading target deck angle deviation Δψ=|ψ j -ψ|, if Δψ < ψ err Then the horizontal tracking frame is driven to rotate to the heading target deck angle ψ calculated in step (306). j and pitch target deck angle E j , ψ err It is the preset deviation angle threshold; otherwise, let ψ = ψ + ψ j Then proceed to step (304) to continue iterative calculation.

[0029] Furthermore, step 4 is specifically implemented as follows:

[0030] (401) Calculate the coordinate system Ox a y a z a With Ox b y b z b The roll angle γ′ between:

[0031] γ′=arctan2(-C[0][2],C[2][2])

[0032] In the formula, C = R x (E)·R y (γ)·R x (θ),E is the pitch deck angle when the horizontal tracking frame is aligned with the space target;

[0033] (402) Calculate the heading correction value ψ′ and assign it to the attitude measurement module to replace its heading output ψ. The calculation method is as follows:

[0034] ψ′=2π-arctan2(-C′[1][0],C′[1][1])

[0035] In the formula, C′=R x (-E)·R y (γ′)·R x (E d )·R z (-A d ).

[0036] A strapdown space target pointing iterative calculation system includes a horizontal tracking frame, a calculation processing module, an attitude measurement module and an incremental encoder mounted on an azimuth rotation platform, wherein the calculation processing module calculates the space target pointing using the method described in any of the preceding claims.

[0037] The beneficial effects of adopting the above technical solution are as follows:

[0038] 1. This invention addresses the drawback of mounting the attitude measurement module on the base of a horizontal tracking frame, which requires precise calibration of the non-levelness of the large disk of the azimuth rotation platform. Instead, the attitude measurement module is mounted on the azimuth rotation platform, and a corresponding heading correction method is derived, reducing the debugging difficulty.

[0039] 2. This invention addresses the shortcomings of incremental encoders used in ground-based tracking frames, which require a zeroing mechanism and an azimuth angle initialization process at startup. It proposes a method using heading as azimuth angle feedback, derives an iterative calculation method for the target angle, avoids the azimuth angle initialization process, saves hardware costs, and effectively reduces startup time. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the composition and coordinate system of the horizontal tracking frame in an embodiment of the present invention;

[0041] Figure 2 This is a flowchart illustrating the iterative calculation of the target deck angle in an embodiment of the present invention;

[0042] Figure 3This is the iterative calculation simulation curve of the heading target deck angle in this embodiment of the invention;

[0043] Figure 4 This is the iterative calculation simulation curve of the pitch target deck angle in this embodiment of the invention. Detailed Implementation

[0044] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] A strapdown-type iterative calculation method for pointing space targets, using a horizontal tracking rig such as... Figure 1 As shown, the azimuth axis uses an incremental encoder, and an attitude measurement module is installed on the azimuth rotation platform. The method includes the following steps:

[0046] (1) Obtain the attitude information output by the attitude measurement module in real time, including heading ψ, roll γ and pitch θ;

[0047] (2) Based on the position information of the space target and the position information of the ground-based tracking frame, calculate the theoretical pointing angle of the ground-based tracking frame relative to the space target, including the theoretical azimuth angle A. d And pitch theory angle E d ;

[0048] (3) Based on the theoretical pointing angle and attitude information, calculate in real time the deck pointing angle of the horizontal tracking frame aligned with the space target, including the heading target deck angle ψ. j and pitch target deck angle E j Drive the tracking frame to rotate to this deck pointing angle;

[0049] (4) After the horizontal tracking frame is aligned with the space target, the heading ψ of the attitude measurement module is corrected.

[0050] Among them, the azimuth theoretical angle A in step (2) d And pitch theory angle E d The calculation method is as follows:

[0051]

[0052]

[0053] In the formula, λ T , H T These represent the longitude, latitude, and altitude of the space target, respectively, λ, H represents the longitude, latitude, and altitude of the horizontal tracking frame, respectively.

[0054] In step (3), the heading target deck angle ψ j and pitch target deck angle E jThe calculation is performed using an iterative method; the calculation flowchart is shown below. Figure 2 The calculation method is as follows:

[0055] (301) Establish the tracking frame pointing coordinate system Ox a y a z a Its coordinate axis x a Parallel to the horizontal plane and pointing to the right, y a The pitch axis perpendicular to the tracking frame points forward, z a With x a y a Construct a right-handed coordinate system; establish the tracking frame azimuth turntable coordinate system Ox b y b z b Its coordinate axis x b The pitch axis, parallel to the tracking frame, points to the right, z b The azimuth axis, parallel to the tracking frame, points upwards, y b With x b z b Construct a right-handed coordinate system;

[0056] (302) Construct the geographic coordinate system Ox n y n z n To Ox a y a z a coordinate transformation matrix

[0057]

[0058] In the formula R x (α), R y (α), R z (α) is a single-axis rotation matrix, and

[0059]

[0060] (303) Initialize the heading target deck angle ψ j =0;

[0061] (304) Constructing the geographic coordinate system Ox n y n z n To Ox b y b z b coordinate transformation matrix

[0062]

[0063] (305) Construct Oxb y b z b To Ox j y j z j coordinate transformation matrix

[0064]

[0065] (306) Calculate the target deck angle ψ of the heading j and pitch target deck angle E j :

[0066]

[0067]

[0068] (307) Calculate the heading target deck angle deviation Δψ=|ψ j -ψ|, if Δψ < ψ err Then the driving tracking frame rotates to the target deck angle ψ calculated by (306). j and pitch target deck angle E j , ψ err This is the preset deviation angle threshold, which can be set to 0.01°; otherwise, let ψ = ψ + ψ j Then proceed to step (304) to continue iterative calculation.

[0069] The simulation curve of the calculated angle is shown in the figure. Figure 3 , Figure 4 .

[0070] Step (4) The method for calculating the heading of the attitude measurement module after the horizontal tracking frame is aligned with the space target is as follows:

[0071] (401) Calculate the coordinate system Ox a y a z a With Ox b y b z b The roll angle γ′ between:

[0072] γ′=arctan2(-C[0][2],C[2][2])

[0073] In the formula, C = R x (E)·R y (γ)·R x (θ),E is the pitch deck angle when the horizontal tracking frame is aligned with the space target;

[0074] (402) Calculate the heading correction value ψ′ and assign it to the attitude measurement module to replace its heading output ψ. The calculation method is as follows:

[0075] ψ′=2π-arctan2(-C′[1][0],C′[1][1])

[0076] In the formula, C′=R x (-E)·R y (γ′)·R x (E d )·R z (-A d ).

[0077] A strapdown-type space target pointing iterative calculation system includes a horizontal tracking frame, a calculation processing module, and an attitude measurement module and an incremental encoder installed on an azimuth rotation platform. The calculation processing module calculates the pointing of the space target using the method described above.

[0078] In summary, this invention addresses the drawback of mounting the attitude measurement module on the base of a horizontal tracking frame, which requires precise calibration of the non-levelness of the azimuth rotation platform. Instead, it mounts the attitude measurement module on the azimuth rotation platform of the horizontal tracking frame, using its heading output angle as azimuth feedback information. Combined with the geographic pointing angle of the space target, an iterative method is used to calculate the theoretical heading angle when the horizontal tracking frame points at the space target, and a corresponding heading angle correction method is derived, thus reducing debugging difficulty. Furthermore, addressing the drawback of using an incremental encoder for the azimuth axis of a horizontal tracking frame, which requires a zeroing mechanism and an azimuth axis angle initialization process at startup, this invention proposes a method using the heading as the azimuth axis angle feedback. An iterative calculation method for the target angle is derived, avoiding the azimuth axis angle initialization process, saving hardware costs, and effectively reducing startup time. It has the advantages of requiring no additional hardware, being simple to implement, and having a wide range of applications.

Claims

1. A strapdown-style iterative calculation method for pointing spatial targets, characterized in that, Includes the following steps: Step 1: Obtain the attitude information output by the attitude measurement module in real time, including heading. , roll And pitch ; Step 2: Based on the position information of the space target and the position information of the ground-based tracking frame, calculate the theoretical pointing angle of the ground-based tracking frame relative to the space target, including the theoretical azimuth angle. And pitch theory angle ; Step 3: Based on the theoretical pointing angle and attitude information, calculate in real time the deck pointing angle of the horizontal tracking frame aligned with the space target, including the heading target deck angle. and pitch target deck angle The drive tracking frame rotates to the deck pointing angle; where the heading target deck angle is... and pitch target deck angle The calculation is performed using an iterative method, specifically as follows: (301) Establish a horizontal tracking frame pointing coordinate system Its coordinate axes Parallel to the horizontal plane, pointing to the right. The pitch axis, perpendicular to the ground-mounted tracking frame, points forward. and , Construct a right-handed coordinate system; establish a coordinate system for the azimuth turntable of the horizontal tracking frame. Its coordinate axes The pitch axis, parallel to the ground-level tracking frame, points to the right. The azimuth axis, parallel to the ground-mounted tracking frame, points upwards. and , Construct a right-handed coordinate system; (302) Constructing a geographic coordinate system arrive coordinate transformation matrix : In the formula , , It is a single-axis rotation matrix, and (303) Initialize the heading target deck angle ; (304) Constructing a geographic coordinate system arrive coordinate transformation matrix : (305) Construction arrive coordinate transformation matrix : (306) Calculate the target deck angle of the course and pitch target deck angle : Where C[i][j] represents the element in the i-th row and j-th column of matrix C; (307) Calculate the deviation of the target deck angle on the course. ,like Then drive the horizontal tracking frame to rotate to the heading target deck angle calculated in step (306). and pitch target deck angle , It is the preset deviation angle threshold; otherwise, let Then proceed to step (304) to continue iterative calculation; Step 4: After the horizontal tracking frame is aligned with the space target, the heading of the attitude measurement module is corrected. .

2. The strapdown-style iterative calculation method for pointing spatial targets according to claim 1, characterized in that, The specific method for step 4 is as follows: (401) Calculate the coordinate system and The roll angle between : In the formula , The pitch angle of the deck when the horizontal tracking frame is aligned with a space target; (402) Calculate the heading correction value The value is assigned to the attitude measurement module to replace its heading output. The calculation method is as follows: In the formula .

3. A strapdown-type space target pointing iterative calculation system, comprising a horizontal tracking frame, characterized in that, It also includes a calculation and processing module, an attitude measurement module and an incremental encoder mounted on an orientation rotation platform, wherein the calculation and processing module calculates the spatial target orientation using the method described in any one of claims 1-2.

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