Agile satellite in-orbit imaging task planning subtask preprocessing method

Abstract

The application discloses a kind of agile satellite in-motion imaging task planning subtask preprocessing method, solve the preprocessing problem of in-motion imaging oblique strip subtask, belong to spacecraft task planning technical field.Subtask preprocessing method includes: (1) the normal side time of calculating subtask endpoint;(2) according to normal side time, determine the optimal push-scan sequence and push-scan direction of subtask;(3) according to optimal push-scan sequence and push-scan direction, calculate the position coordinates of subtask preposition outer extension point.The application method is suitable for single oblique strip, oblique strip splicing and oblique strip splicing and other various in-motion imaging modes;The application method is suitable for sun synchronous orbit and low-inclination orbit satellite, and the best push-scan direction of strip can be determined based on satellite flight orbit.

Description

Technical Field

[0001] This invention relates to a preprocessing method for planning meta-missions in agile satellite imaging missions while in motion, belonging to the field of spacecraft mission planning technology. Background Technology

[0002] Traditional imaging methods for agile optical remote sensing satellites are passive imaging, meaning the satellite relies solely on orbital motion for pushbroom imaging, maintaining a fixed attitude throughout the process, with the imaging stripe direction parallel to the nadir. With improved satellite attitude maneuverability, a new pushbroom imaging method has emerged, combining orbital motion with attitude maneuvering, often simply called "imaging in motion." In this method, the imaging stripe direction typically forms an angle with the nadir.

[0003] Agile satellite imaging in motion employs three modes: single-slope imaging, slope stitching, and slope patching. A slope is the meta-task of in-motion imaging, defined as a great circle arc (minor arc) passing through the Earth's center, determined by any two points on the Earth's surface, with the slope width equal to the camera's swath width. Single-slope imaging images a slope at any angle to the nadir trajectory, suitable for line targets. Slope stitching imaging connects multiple slopes end-to-end, suitable for observing narrow, curved targets such as borders, rivers, and coastlines. Slope patching imaging stitches multiple slopes together to achieve wider target coverage. During in-motion imaging mission planning, after the target is divided into slopes, a preprocessing stage is necessary to determine the optimal push-broom direction and corresponding pre-tracking points. Only then can the meta-task serve as input for subsequent mission scheduling. Pre-tracking points are pre-tracking points required by the control subsystem to ensure stable tracking of the slope's starting position. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and solve the preprocessing problem of the oblique strip element task in dynamic imaging.

[0005] The objective of this invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a preprocessing method for planning meta-tasks in agile satellite imaging missions, comprising:

[0007] (1) Calculate the forward and side-view time of the meta-task endpoint;

[0008] (2) Determine the optimal push-broom sequence and push-broom direction of the meta-task based on the forward and side-view time;

[0009] (3) Calculate the position coordinates of the pre-extension point of the meta-task based on the optimal push-broom sequence and push-broom direction.

[0010] In a second aspect, the present invention provides a computer-readable storage medium having stored thereon computer program instructions, which, when loaded and run by a processor, cause the processor to perform the method described in the first aspect.

[0011] Thirdly, the present invention provides a computer program product stored on a non-transitory computer-readable medium, the computer program product including program code for performing the method described in the first aspect.

[0012] Fourthly, the present invention provides an electronic device, comprising:

[0013] Processor; and

[0014] Memory is used to store computer program instructions;

[0015] When the computer program instructions are loaded and run by the processor, the processor performs the method described in the first aspect.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The method of the present invention is applicable to various in-motion imaging modes such as single oblique strip, oblique strip splicing and oblique strip patching;

[0018] (2) The method of the present invention is applicable to satellites in sun-synchronous orbit and low-inclination orbit, and can determine the optimal push-broom direction of the strip based on the satellite's flight trajectory;

[0019] (3) The method of the present invention takes into account the need for early stable tracking of the control subsystem and can provide the pre-extension point of the meta-task. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the meta-task preprocessing method of the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the optimal push-broom direction adjustment for the single-slope strip mode meta-task.

[0022] Figure 3 This is a schematic diagram showing the optimal push-broom sequence and direction adjustment for the meta-task in the oblique strip splicing mode.

[0023] Figure 4 This is a schematic diagram showing the optimal push-broom sequence and direction adjustment for the meta-task in the oblique strip splicing mode.

[0024] Figure 5 This is a schematic diagram illustrating the calculation of the coordinates of the pre-extension points for the meta-task. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] A preprocessing method for planning meta-tasks in agile satellite imaging missions, such as... Figure 1 As shown, it includes the following steps:

[0027] (1) Calculate the forward and side-view time of the meta-task endpoint.

[0028] Each diagonal strip metatask consists of two endpoints: the first endpoint is the start point, and the second endpoint is the end point. The sweep direction of the strip is from the start point to the end point. The forward look-ahead time of the metatask endpoint is defined as follows: if the satellite's elevation angle is zero when it points to a certain endpoint of the target at time t, then t is called the forward look-ahead time of that endpoint.

[0029] For the single-slope strip mode, the forward and side-looking times t1 and t2 corresponding to the starting point p1 and ending point p2 of the meta-task are calculated based on satellite orbit data, respectively. Figure 2 As shown.

[0030] For the diagonal strip splicing mode, assuming a splicing group contains n diagonal strip meta-tasks connected end-to-end, with an initial order of meta-task 1, meta-task 2, ..., meta-task n, then the starting point p of meta-task 1 is calculated based on satellite orbit data. 11 The endpoint p of task n n2 The corresponding time for viewing forward and backward is t. 11 and t n2 ,like Figure 3 As shown in the figure, the splicing group contains 3 meta-tasks.

[0031] For the oblique strip stitching mode, assume a stitching group contains n oblique strip meta-tasks alternating between forward and reverse scans, initially ordered as meta-task 1, meta-task 2, ..., meta-task n. Odd-numbered meta-tasks are forward scans, and even-numbered meta-tasks are reverse scans. The starting point p of meta-task 1 is calculated based on satellite orbit data. 11 and the endpoint p 12 The corresponding time for viewing forward and backward is t. 11 and t 12 Calculate the starting point p of the meta-task n. n1 and the endpoint p n2 The corresponding time for viewing forward and backward is t. n1 and t n2 ,like Figure 4 As shown in the figure, the splicing group contains 3 meta-tasks.

[0032] (2) Determine the optimal push order and push direction of the meta-task.

[0033] For single-slope strip mode, if the forward and side-looking times t1 and t2 corresponding to the starting point p1 and ending point p2 of the meta-task satisfy t1≤t2, the current pushbroom direction is the optimal pushbroom direction and no adjustment is needed. Figure 2 (a) shows the optimal sweep direction; otherwise, the optimal sweep direction is from p2 to p1, and the starting and ending points need to be swapped, as shown in (a). Figure 2 As shown in (b).

[0034] For the diagonal strip splicing mode, if the starting point of meta-task 1 is p 11 The endpoint p of task n n2 The time t for viewing the front and side 11 and t n2 Satisfying t 11 ≤t n2 The current push-broom sequence and direction are optimal and do not require adjustment. Figure 3 (a) shows the following; otherwise, adjust the push-broom order to: metatask n, metatask n-1, ..., metatask 1, and reverse the push-broom direction of each metatask, that is, swap the starting point and the ending point.

[0035] For the diagonal strip splicing mode, based on the starting point p of meta-task 1 11 and the endpoint p 12 The time t for viewing the front and side 11 and t 12 Meta-task n starting point p n1 and the endpoint p n2 The time t for viewing the front and side n1 and t n2 There are four possible scenarios:

[0036] a)min(t 11 ,t 12 )≤min(t n1 ,t n2 And t 11 ≤t 12 The current push order and push direction are the optimal push direction and do not need to be adjusted. Figure 4 As shown in (a);

[0037] b)min(t 11 ,t 12 )>min(t n1 ,t n2 ), and t n1 >t n2 The push-broom order is adjusted to: meta-task n, meta-task n-1, ..., meta-task 1, with odd-numbered tasks set as forward sweeps and even-numbered tasks as reverse sweeps. The push-broom direction of each meta-task is reversed, i.e., the start and end points are swapped. Figure 4 As shown in (b);

[0038] c)min(t 11 ,t 12 )≤min(t n1 ,t n2 And t 11 >t 12 The push-broom order remains unchanged: meta-task 1, meta-task 2, ..., meta-task n. The forward and reverse scan settings for each strip remain the same, but the push-broom direction for each meta-task must be reversed, i.e., the start and end points are swapped. For example... Figure 4 As shown in (c);

[0039] d)min(t 11 ,t 12 )>min(t n1 ,t n2 ), and t n1 ≤t n2 The push-broom order is adjusted to: meta-task n, meta-task n-1, ..., meta-task 1, with odd-numbered orders set as forward scans and even-numbered orders set as reverse scans. The push-broom direction of each meta-task remains unchanged. Figure 4 As shown in (d).

[0040] (3) Calculate the position coordinates of the pre-extension point of the meta-task.

[0041] First, calculate the Earth-fixed vectors at the starting point A and ending point B of the oblique strip element task: x a ,y a ,z a Let A be the coordinates of point A in the Earth-fixed system. x b ,y b ,z b Let B be the coordinates of point B in the Earth-fixed system.

[0042] calculate and The angle between

[0043]

[0044] R A and R B They are and Length.

[0045] like Figure 5 As shown. Establish a new coordinate system Ox n y n z n x n The axis is z n The axis is

[0046] y n The axes follow the right-hand rule. Therefore, the transformation matrix A between this coordinate system and the Earth-fixed system is... en for:

[0047]

[0048]

[0049] Assume the push-broom angular velocity is kω s ω s Let be the orbital angular velocity of the satellite, and k be the angular velocity coefficient.

[0050] The pre-tracking point for the meta-task is the coordinate point at which the control subsystem begins tracking in advance to ensure the imaging quality of the meta-task. This point is located on the great circle arc where the meta-task is situated. Figure 5 Point E in the diagram is the pre-task expansion point. Assuming the advance tracking time is Δt, the angle θ between OE and OA is kω. s Δt.

[0051] Then the vector of the preceding expansion point E in the Earth-fixed system is:

[0052] in,

[0053] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0054] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A preprocessing method for planning meta-tasks in agile satellite imaging missions, characterized in that, include: (1) Calculate the forward and side-view time of the meta-task endpoint; (2) Determine the optimal push-broom sequence and push-broom direction of the meta-task based on the forward and side-view time; (3) Calculate the position coordinates of the pre-extension point of the meta-task based on the optimal push-broom sequence and push-broom direction.

2. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 1, characterized in that, The forward look-ahead time of a meta-mission endpoint is defined as follows: if the satellite's elevation angle is zero when it points to a certain endpoint of the target at time t, then t is called the forward look-ahead time of that endpoint.

3. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 1, characterized in that, For the single-slope strip mode, the frontal and side-view times t1 and t2 corresponding to the starting point p1 and ending point p2 of the meta-task are calculated based on the satellite orbit data, respectively. For the diagonal strip splicing mode, assuming a splicing group contains n diagonal strip meta-tasks connected end-to-end, with an initial order of meta-task 1, meta-task 2, ..., meta-task n, then the starting point p of meta-task 1 is calculated based on satellite orbit data. 11 The endpoint p of task n n2 The corresponding time for viewing forward and backward is t. 11 and t n2 ; For the oblique strip stitching mode, assume a stitching group contains n oblique strip meta-tasks alternating between forward and reverse scans, initially ordered as meta-task 1, meta-task 2, ..., meta-task n. Odd-numbered meta-tasks are forward scans, and even-numbered meta-tasks are reverse scans. The starting point p of meta-task 1 is calculated based on satellite orbit data. 11 and the endpoint p 12 The corresponding time for viewing forward and backward is t. 11 and t 12 Calculate the starting point p of the meta-task n. n1 and the endpoint p n2 The corresponding time for viewing forward and backward is t. n1 and t n2 .

4. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 3, characterized in that, For single-slope strip mode, if the forward and side-looking times t1 and t2 corresponding to the starting point p1 and ending point p2 of the meta-task satisfy t1≤t2, the current push-broom direction is the optimal push-broom direction and no adjustment is needed; otherwise... The optimal sweep direction is from p2 to p1, and the starting and ending points need to be swapped.

5. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 3, characterized in that, For the diagonal strip splicing mode, if the starting point of meta-task 1 is p 11 The endpoint p of task n n2 The time t for viewing the front and side 11 and t n2 Satisfy t 11 ≤t n2 The current push-broom sequence and direction are optimal and do not require adjustment. Otherwise, adjust the push-broom order to: metatask n, metatask n-1, ..., metatask 1, and reverse the push-broom direction of each metatask, that is, swap the starting point and the ending point.

6. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 3, characterized in that, For the diagonal strip splicing mode, based on the starting point p of meta-task 1 11 and the endpoint p 12 The time t for viewing the front and side 11 and t 12 Meta-task n starting point p n1 and the endpoint p n2 The time t for viewing the front and side n1 and t n2 There are four possible scenarios: a)min(t 11 ,t 12 )≤min(t n1 ,t n2 And t 11 ≤t 12 The current push order and push direction are the optimal push direction and do not need to be adjusted. b)min(t 11 ,t 12 )>min(t n1 ,t n2 ), and t n1 >t n2 The push-broom order is adjusted to: metatask n, metatask n-1, ..., metatask 1. Odd-numbered orders are set as forward sweeps, and even-numbered orders are set as reverse sweeps. The push-broom direction of each metatask is reversed, that is, the starting point and the ending point are swapped. c)min(t 11 ,t 12 )≤min(t n1 ,t n2 And t 11 >t 12 The push-broom order remains unchanged as metatask 1, metatask 2, ..., metatask n. The forward and reverse sweep settings for each strip remain unchanged, but the push-broom direction of each metatask must be reversed, that is, the starting point and the ending point are swapped. d)min(t 11 ,t 12 )>min(t n1 ,t n2 ), and t n1 ≤t n2 The push-broom order is adjusted to: metatask n, metatask n-1, ..., metatask 1, with odd-numbered orders set as forward scans and even-numbered orders set as reverse scans, while the push-broom direction of each metatask remains unchanged.

7. The preprocessing method for planning meta-tasks in agile satellite imaging missions according to claim 1, characterized in that, Step (3) includes: First, calculate the Earth-fixed vectors at the starting point A and ending point B of the oblique strip element task: x a ,y a ,z a Let A be the coordinates of point A in the Earth-fixed system. x b ,y b ,z b Let B be the coordinates of point B in the Earth-fixed system. calculate and The angle between R A and R B They are and Length; Establish a new coordinate system Ox n y n z n x n The axis is z n The axis is y n If the axes conform to the right-hand rule, then the transformation matrix A between this coordinate system and the Earth-fixed system is... en for: Assume the push-broom angular velocity is kω s ω s Let be the orbital angular velocity of the satellite, and k be the angular velocity coefficient; Assuming the advance tracking time is Δt, then the angle θ between OE and OA is kω. s Δt; Then the vector of the preceding expansion point E in the Earth-fixed system is: in, 8. A computer-readable storage medium having stored thereon computer program instructions, which, when loaded and run by a processor, cause the processor to perform the method as described in any one of claims 1 to 7.

9. A computer program product stored on a non-transitory computer-readable medium, the computer program product comprising program code for performing the method as described in any one of claims 1 to 7.

10. An electronic device, comprising: processor; as well as Memory is used to store computer program instructions; When the computer program instructions are loaded and run by the processor, the processor performs the method as described in any one of claims 1 to 7.

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