Optimal strip division method for agile satellite area target motion imaging

Abstract

The application discloses an agile satellite regional target moving imaging optimal strip division method, solves the problem of optimal strip division of a regional target in moving imaging, and belongs to the technical field of spacecraft task planning. The optimal strip division method comprises the following steps: S1, determining linear equations of longitude and latitude of each boundary line of a regional target; S2, calculating the minimum number of strips covered by the regional target and obtaining a set of available strip division directions by using the slopes of the linear equations of longitude and latitude of each boundary line in S1; and S3, determining a strip division direction with the minimum total length of strips and calculating the position coordinates of boundary points of each strip by using the linear equations of longitude and latitude of each boundary line in S1, the minimum number of strips in S2 and the set of available strip division directions. The method disclosed by the application does not need complex trigonometric function calculation and large-scale optimization, has small calculation complexity, and is suitable for both ground task planning and autonomous task planning on a satellite.

Description

Technical Field

[0001] This invention relates to an optimal strip division method for dynamic imaging of regional targets on agile satellites, 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 satellites image regional targets using multiple stripe patterns. These can be passive imaging strips parallel to the nadir line or moving imaging strips not along the track. Generally, moving imaging, which supports both forward and reverse scanning, is more efficient at achieving regional target coverage than passive imaging. In the planning of moving imaging missions for regional targets, the quality of stripe division directly affects the planning results. Existing agile satellite regional target imaging mission planning primarily addresses passive imaging problems, with the few involving moving imaging only focusing on stripe division perpendicular to the nadir line. Given the diverse shapes of regional targets, selecting the optimal stripe division direction to minimize the number of stripes and the total imaging time is a key challenge in planning moving imaging missions for regional targets. 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 problem of optimal strip division of the target in the moving imaging region.

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

[0006] In a first aspect, the present invention provides an optimal striping method for dynamic imaging of regional targets using agile satellites, comprising:

[0007] S1. Determine the linear equations of latitude and longitude for each boundary line of the target area;

[0008] S2. Using the slope of the linear equations of latitude and longitude of each boundary line in S1, calculate the minimum number of strips to cover the target area and obtain the set of available strip division directions.

[0009] S3. Using the linear equations of latitude and longitude of each boundary line in S1, the minimum number of strips in S2, and the set of available strip division directions, determine the strip division direction with the minimum total strip length and calculate the position coordinates of each strip boundary point.

[0010] Based on the first aspect, in one embodiment of the present invention, step S1 includes:

[0011] S11: Find the maximum and minimum longitudes of all boundary vertices, MaxLon and MinLo;

[0012] S12: Determine the straight line equations of each side of the polygon based on the latitude and longitude coordinates of the two vertices of the boundary line.

[0013] Based on the first aspect, in one embodiment of the present invention, in S11, if MaxLon–MinLon>π, it means that the region spans a 180° meridian and needs to be translated.

[0014] Based on the first aspect, in one embodiment of the present invention, the translation rule is: if lon i <0, then lon i =-π-lo i n; otherwise lon i =π-lon i lon i Let be the longitude of the i-th vertex of the regional target.

[0015] Based on the first aspect, in one embodiment of the present invention, step S2 includes:

[0016] S21: Calculate the slope of each boundary vertex as k. i The set of equations of straight lines;

[0017] S22: Find the two parallel lines L that are farthest apart in the set of linear equations. i1 and L i2 ;

[0018] S23: Calculate the equation L of the line that passes through the first vertex A and is perpendicular to the i-th boundary line. i3 ;

[0019] S24: Calculate L respectively i3 With L i1 L i2 Intersection F i1 and F i2 ;

[0020] S25: Calculate F i1 Point and F i1 Distance between points MaxDis i ;

[0021] S26: Based on the effective observation swath λ of the nadir point when the camera is in zero satellite attitude, determine the set of strip numbers when the strip direction is parallel to each boundary line of the region, and find the minimum number of divisions.

[0022] Based on the first aspect, in one embodiment of the present invention, step S3 includes:

[0023] S31: Based on the strip division corresponding to the minimum number of divisions, calculate the boundary line equations of each strip;

[0024] S32: Calculate the boundary vertices of each strip;

[0025] S33: Calculate the length of each strip based on the boundary vertices of each strip, then calculate the total length of all strips, and find the strip division direction slope and corresponding strip boundary point with the minimum total strip length.

[0026] Based on the first aspect, in one embodiment of the present invention, the method for determining the number of strip divisions is as follows:

[0027]

[0028] ceiling means rounding up to the nearest whole number.

[0029] 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.

[0030] Thirdly, the present invention provides 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 the first aspect.

[0031] Fourthly, the present invention provides an electronic device, comprising:

[0032] Processor; and

[0033] Memory is used to store computer program instructions;

[0034] When the computer program instructions are loaded and run by the processor, the processor performs the method as described in the first aspect.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The method of the present invention obtains the regional target strip division results with the fewest number and the smallest total strip length, which helps to ensure and improve the efficiency of satellite on-orbit observation and reduce invalid image recording data;

[0037] (2) The strips obtained by the method of the present invention will uniformly cover the regional target, that is, the center line of all strips coincides with the center line of the regional target, thus ensuring accurate coverage of the satellite observation target;

[0038] (3) The method of the present invention does not require complex trigonometric function calculations and does not require large-scale optimization. It has low computational complexity and is applicable to both ground mission planning and on-board autonomous mission planning. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating the strip division method of the present invention.

[0040] Figure 2 A schematic diagram illustrating the calculation of the minimum number of stripes and the determination of the available strip division directions.

[0041] Figure 3 A schematic diagram illustrating the determination of the strip division direction with the minimum total strip length and the calculation of strip boundary points. Detailed Implementation

[0042] 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.

[0043] An optimal striping method for dynamic imaging of regional targets using agile satellites, such as... Figure 1 As shown, it includes the following steps:

[0044] S1. Calculate the latitude and longitude linear equations of each boundary line of the target area.

[0045] Given the set of geographic longitude and latitude of the target region m (m > 2 boundary vertices) {(lon i ,lat i ) m}, i = 1, ..., m; latitude and longitude units are: rad.

[0046] S11: Find the maximum and minimum longitudes (MaxLon and MinLon) of all boundary vertices. If MaxLon - MinLon > π, it means the region spans 180° of longitude, and the region needs to be translated. The translation rule is: if π / 2 > π / 2, then π / 2 > π / 2. i <0, then lon i =-π-lon i Otherwise lon i =π-lon i ;lon i Let be the longitude of the i-th vertex of the regional target.

[0047] S12: Based on the latitude and longitude coordinates of the two vertices of the boundary line, calculate the straight line equation y = k for each side of the polygon. i x+b i ,i=1,…,m. Where x represents longitude, y represents latitude, and k i Let b be the slope of the equation of the i-th boundary line. i Let be the constant term of the equation of the i-th boundary line, such as Figure 2 As shown.

[0048] S2. Using the slope of the latitude and longitude linear equations of each boundary line described in S1, calculate the minimum number of strips required to cover the target area and obtain a set of available strip division directions.

[0049] According to conclusions in computational geometry, for a polygon, the direction of its minimum width must be consistent with the normal direction of some edge. That is, the direction of the strip division with the minimum number of strips must be parallel to some edge of the polygon.

[0050] like Figure 2 As shown, assuming the strip direction is parallel to the i-th boundary line (CD) of the region, the number of stripes is calculated as follows.

[0051] S21: Calculate the slope of each boundary vertex as k. i The set of equations of straight lines {(y=k i x+b ij ) m}, the first ordinal number j = 1, ..., m, b ij For the slope of the j-th boundary vertex, k i The constant term of the equation of the straight line.

[0052] S22: Find the two parallel lines L that are furthest apart in the above set. i1 y = k i x+b ip and L i2 y = k i x+b iq 1≤p,q≤m, where p is the second ordinal number and q is the third ordinal number.

[0053] S23: Calculate the equation L of the line that passes through the first vertex A and is perpendicular to the i-th boundary line. i3 y = -x / k i +c i c i Let be the constant term of the i-th linear equation.

[0054] S24: Calculate L respectively i3 With L i1 L i2 The intersection point F i1 and F i2 Their position coordinates are (x i1 ,y i1 ) and (x i2 ,y i2 ).

[0055] S25: Calculate F i1 Point and F i1 Distance between points MaxDisi .

[0056]

[0057] and It is F i1 Point and F i1 The geocentric position vector of a point, R is the geocentric distance of the region, which is the average geocentric distance of each boundary vertex, in km.

[0058] S26: Assuming the effective swath width of the camera at the nadir point when the satellite is in zero attitude is λ, then the number of strip divisions is:

[0059]

[0060] ceiling indicates rounding up. λ is the effective swath width of the camera at the nadir point when the satellite is at zero attitude, in km.

[0061] By repeating S21 to S26, we can obtain the set of strip numbers {(N) when the strip direction is parallel to each boundary line of the region. i ) m If}, i=1,…,m, then the minimum number of partitions is

[0062] MinStripNum=min{(N i ) m}

[0063] MinStripNum may correspond to n strip directions, represented by the set of strip slopes {(k i ) n}express.

[0064] S3. Using the linear equations of latitude and longitude of each boundary line described in S1, the minimum number of strips described in S2, and the set of selectable strip division directions, determine the strip division direction with the minimum total strip length and calculate the position coordinates of each strip boundary point.

[0065] like Figure 3 As shown, assume the slope of the strip corresponding to MinStripNum is k. i The steps for calculating the total length of the corresponding strip are as follows.

[0066] S31: Calculate the boundary line equations for each strip.

[0067] The actual coverage width of each stripe, MinStripNum, is Dis = MinStripNum·λ. Generally, Dis > MaxDis. i This means that the area after strip splicing will exceed the range of the observed target. The strip division rules are as follows:

[0068] (a) The center lines of the divided zone areas should be aligned with the center lines of the zone targets;

[0069] (b) The observation area extends to both sides to maximize the observation area.

[0070] Point G is F i1 and F i2 The midpoint of the point is then its latitude and longitude coordinates are:

[0071] x G =(x i1 +x i2 ) / 2

[0072] y G =(y i1 +y i2 ) / 2

[0073] According to the above rules, the boundary line of the j-th stripe is parallel to L. i3 The intersection point g j The latitude and longitude coordinates of points g0 to g4 in the figure are:

[0074] x j =η(x) i1 -x G )+x G +jη(x i1 -x i2 ) / MinStripMum

[0075] y j =η(y i1 -y G )+y G +jη(y i1 -y i2 ) / MinStripMum

[0076] j = 0, 1, ..., MinStripNum, η = DisMaxDis. Therefore, the boundary line of the j-th strip is the line passing through point g. j The slope is k i The straight line BL j y = k i x+d ij .

[0077] S32: Calculate the boundary vertices of each stripe.

[0078] First, assign all the region boundary vertices to their respective stripes.

[0079] When the vertex satisfy At that time, the vertex is located within the (j+1)th strip. For example, in Figure 3In the diagram, point A is located within strip 4.

[0080] Next, calculate the intersection points of each strip boundary line with each boundary of the regional target. For example, in Figure 3 In the middle, the intersection of the boundary line of strip 4 and the target boundary line is at two points, M and N.

[0081] Then determine the two points in each strip that are the vertices contained within it and have the largest distance from the intersection point with the region boundary along the strip direction. For example, Figure 3 In strip 4, the two points with the greatest distance between points A, M, and N in the strip direction are points M and N.

[0082] Finally, by calculating the intersection points of the lines perpendicular to the strip and passing through the two points with the largest distance mentioned above with the strip boundary, we can obtain the four boundary points of the strip. For example, in Figure 3 In the diagram, the four boundary points of strip 1 are points h1, h2, h3, and h4.

[0083] If the original target area spans a 180° meridian, the strip boundary points also need to be shifted in the opposite direction.

[0084] S33: Calculate the length of each strip based on the previously obtained strip boundary point coordinates, and then calculate the total length of all strips.

[0085] The set {(k) is traversed using steps S31 to S33 as described above. i ) n Given n elements of a given set, we can find the strip division direction slope k that minimizes the total strip length. optimal and the corresponding strip boundary points.

[0086] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0087] 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 method for optimal strip division in dynamic imaging of regional targets using agile satellites, characterized in that, include: S1. Determine the linear equations of latitude and longitude for each boundary line of the target area; S2. Using the slope of the linear equations of latitude and longitude of each boundary line in S1, calculate the minimum number of strips to cover the target area and obtain the set of available strip division directions. S3. Using the linear equations of latitude and longitude of each boundary line in S1, the minimum number of strips in S2, and the set of available strip division directions, determine the strip division direction with the minimum total strip length and calculate the position coordinates of each strip boundary point.

2. The optimal strip division method for dynamic imaging of regional targets by agile satellites according to claim 1, characterized in that, Step S1 includes: S11: Find the maximum and minimum longitudes of all boundary vertices, MaxLon and MinLo; S12: Determine the straight line equations of each side of the polygon based on the latitude and longitude coordinates of the two vertices of the boundary line.

3. The optimal strip division method for dynamic imaging of agile satellite regional targets according to claim 2, characterized in that, In S11, if MaxLon-MinLon>π, it means that the region spans a 180° meridian and needs to be translated.

4. The optimal strip division method for dynamic imaging of agile satellite regional targets according to claim 3, characterized in that, The translation rules are as follows: If lon i <0, then lon i =-π-lon i Otherwise lon i =π-lon i ;lon i Let be the longitude of the i-th vertex of the regional target.

5. The optimal strip division method for dynamic imaging of regional targets by agile satellites according to claim 1, characterized in that, Step S2 includes: S21: Calculate the slope of each boundary vertex as k. i The set of equations of straight lines; S22: Find the two parallel lines L that are farthest apart in the set of linear equations. i1 and L i2 ; S23: Calculate the equation L of the line that passes through the first vertex A and is perpendicular to the i-th boundary line. i3 ; S24: Calculate L respectively i3 With L i1 L i2 Intersection F i1 and F i2 ; S25: Calculate F i1 Point and F i1 Distance between points MaxDis i ; S26: Based on the effective observation swath λ of the nadir point when the camera is in zero satellite attitude, determine the set of strip numbers when the strip direction is parallel to each boundary line of the region, and find the minimum number of divisions.

6. The optimal strip division method for dynamic imaging of regional targets by agile satellites according to claim 5, characterized in that, Step S3 includes: S31: Based on the strip division corresponding to the minimum number of divisions, calculate the boundary line equations of each strip; S32: Calculate the boundary vertices of each strip; S33: Calculate the length of each strip based on the boundary vertices of each strip, then calculate the total length of all strips, and find the strip division direction slope and corresponding strip boundary point with the minimum total strip length.

7. The optimal strip division method for dynamic imaging of agile satellite regional targets according to claim 5, characterized in that, The method for determining the number of stripes is as follows: ceiling means rounding up to the nearest whole number.

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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