Field-of-view-gated all-time star sensor star point dealiasing method and system

Abstract

The application discloses a star point demixing method based on field of view gating of an all-weather star sensor, which comprises the following steps: step S100, calculating the displacement difference of two star point coordinates in the two image planes before and after the movement of the star sensor; step S200, calculating the displacement difference of the two star points on the virtual primary image plane before and after the movement of the star sensor; and step S300, combining the displacement difference of the star points in the two image planes and the virtual primary image plane, calculating the relative position relationship between the star points, and performing the star point demixing operation. The application can realize the star point demixing in a short time, make the star points correspond to the gating field of view one by one, and has the advantages of simple calculation method, realization of the algorithm purpose without multiple matching, guarantee of the real-time performance of the algorithm, and high calculation accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of star sensor, in particular to a method and system for resolving star point aliasing of all-weather star sensor based on field of view gating. BACKGROUND

[0002] Star sensor is an important technical means and core product for spacecraft autonomous attitude measurement, and has been widely used in various satellites, spacecraft, deep space probes and other aerospace fields. However, there are great differences between the application environment in the atmosphere and the space environment. The strong sky background irradiation in the daytime is the biggest problem hindering the application of star sensor in the atmosphere.

[0003] In the prior art, the imaging system of the daytime star sensor realizes the function of field of view gating through the micro lens, and simultaneously realizes the rapid gating of the micro lens field of view by using the micro switch array equipped below the micro lens, so as to realize the all-weather star sensor capable of identifying star map under the strong daylight background. The patent (publication number: CN113670299A) "a serial-parallel combined field of view gating imaging method for star sensor" proposes a serial / parallel combined field of view gating imaging working mode of all-weather star sensor, solves the problem of time delay between star point images caused by slow serial gating, and also proposes a method for solving the image compression and aliasing problem of parallel gating. However, the existing technology still has the following problems: the method proposed by the existing technology uses the combination matching of star points in the previous and next two frames, and uses the attitude information at the previous moment to filter out the wrong combination, so that the matching time required by the method is longer and the real-time performance is poorer. SUMMARY

[0004] The purpose of the present application is to provide a method and system for resolving star point aliasing of all-weather star sensor based on field of view gating, which overcomes the problem of long matching time and poor real-time performance of the existing aliasing resolution method. The method uses a combination working mode for image acquisition. In the image processing of the parallel working mode, the method proposed in the present application can use the displacement of star points between adjacent two frames to determine the relative position relationship between different star points. According to the opening and closing state of the micro switch, a one-to-one correspondence between the star points in the secondary image plane and the gated field of view can be established, so as to achieve the purpose of resolving star point aliasing. Compared with the aliasing resolution method mentioned in the prior art, the method of the present application can more quickly achieve the purpose of resolving star point aliasing, and has better real-time performance.

[0005] The present application is realized by the following technical solutions:

[0006] The first aspect of the present application discloses a method for resolving star point aliasing of all-weather star sensor based on field of view gating, comprising the following steps:

[0007] Step S100, calculate the displacement difference of two star point coordinates in the two image planes before and after the star sensor movement;

[0008] Step S200, calculate the displacement difference of two star points on the virtual primary image plane before and after the star sensor movement;

[0009] Step S300, combine the displacement difference of star points on the two image planes and the virtual primary image plane, calculate the relative position relationship between the star points, and perform the star point dealiasing operation.

[0010] Further, the step S100 includes:

[0011] Step S110, obtain the displacement difference of two star points on the secondary image plane direction and direction ;

[0012] Step S120, according to the all-time star sensor field gating imaging principle, obtain the relationship between the virtual primary image plane star point physical coordinates and the secondary image plane star point pixel coordinates ;

[0013] Step S130, according to the displacement difference of two star points on the secondary image plane direction and direction , and the relationship between the virtual primary image plane star point physical coordinates and the secondary image plane star point pixel coordinates , obtain the relationship between the displacement difference of the primary image plane , and the displacement difference of the secondary image plane , .

[0014] Further, the step S200 includes:

[0015] Step S210, obtain the relationship between the star vector of a star and its physical coordinates on the virtual primary image plane ;

[0016] Step S220, the star moves from time to time , obtain the displacement difference of the star direction and Displacement change in direction ;

[0017] Step S230: The star sensor is Time has come The motion of the moment is decomposed into Axis rotation , around Axis rotation , around Axis rotation Superposition of motion.

[0018] Further, the step S300 includes: Time has come The displacement of the star point on the secondary image plane between the times is determined The relative position relationship of the star points in the virtual primary image plane at each moment; by combining multiple relative position relationships, the relative position relationship of all the star points in the virtual primary image plane can be obtained.

[0019] Furthermore, in step S300, it is assumed that there are three star points in the secondary image plane, namely 、 、 , through the displacement relationship of the three star points on the secondary image plane in two adjacent frames, the relative position relationship of the star points in the previous frame on the virtual primary image plane is obtained. The opening and closing state of the micro switch of the star sensor is used to obtain the time When the star sensor field of view is selected, a matching relationship is obtained, so that the star points in the secondary image plane correspond one to one with the microlens field of view, and star point solver is realized.

[0020] The present invention also relates to a star point de-aliasing system for a star sensor at all times based on field of view gating, comprising:

[0021] The first displacement difference calculation module is used to calculate the displacement difference of the coordinates of two star points in the secondary image plane before and after the star sensor moves;

[0022] The second displacement difference calculation module is used to calculate the displacement difference between two star points on the virtual primary image plane before and after the star sensor moves;

[0023] The star point de-aliasing module is used to combine the star point displacement difference between the secondary image plane and the virtual primary image plane, calculate the relative position relationship between the star points, and perform star point de-aliasing operations.

[0024] The present invention also relates to an electronic device, comprising:

[0025] at least one processor; and,

[0026] A memory in communication with the at least one processor; wherein

[0027] The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method.

[0028] The present application also relates to a non-transitory computer readable storage medium storing computer instructions for causing the computer to perform the method.

[0029] The technical scheme of the present application can achieve the following beneficial technical effects:

[0030] The present application can realize star point dealiasing in a short time, one-to-one correspondence between star points and strobed fields, and a simple calculation method, and the algorithm purpose can be realized without multiple matching, which can ensure the real-time performance of the algorithm, and the calculation accuracy is relatively high, and according to the current simulation verification effect, the success rate of the algorithm can reach more than 97%, and the present application provides a more rapid star point dealiasing method, which has better real-time performance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A flowchart of the all-weather star sensor star point dealiasing method based on field of view strobing of the present application;

[0032] Figure 2 A secondary image plane star point movement schematic diagram of the present application;

[0033] Figure 3 A virtual primary image plane star point movement schematic diagram of the present application;

[0034] Figure 4 A three-star point relative position relationship schematic diagram of the present application; wherein, Figure 4 (a) is a star point relative position relationship at t0; Figure 4 (b) is a star point relative position relationship at t1

[0035] Figure 5 A field of view strobing situation schematic diagram of the present application;

[0036] Figure 6 A star point and microlens strobed field matching relationship schematic diagram of the present application;

[0037] Figure 7 A field of view strobing state diagram of the embodiment of the present application;

[0038] Figure 8 A secondary image plane image of two adjacent frames of the embodiment of the present application; ​​

[0039] Figure 9 This is a schematic diagram of the relative position relationship obtained by calculating the three-star points in an embodiment of the present invention, wherein: Figure 9 (a) is an embodiment of the present invention The relative position relationship of the star points at ; Figure 9 (b) is an embodiment of the present invention The relative position relationship of the star points at ;

[0040] Figure 10 The matching result of the star point and the gated field of view in the embodiment of the present invention;

[0041] Figure 11 This is a virtual primary image plane star map according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0044] Apply the combined working mode to acquire images, turn on the micro switches in sequence, and image the virtual primary image plane area within the gated field of view on the secondary image plane to determine the gated field of view where the star point exists. Then turn on the micro switches corresponding to all the gated field of view areas where the star point exists at the same time to perform imaging. Figure 1 shown.

[0045] Figure 1 The coordinate systems involved are:

[0046] Star sensor coordinate system: , with the optical axis as Axis, with the optical center of the image side telecentric lens as point. The direction is consistent with the row direction of the virtual primary image plane. The direction is consistent with the column direction of the virtual primary image plane and conforms to the right-hand rectangular coordinate system.

[0047] Virtual primary image plane coordinate system: Since there is no image in this coordinate system, the unit is mm. The origin is the intersection of the optical axis of the star sensor and the virtual primary image plane. The direction is the row direction of the virtual primary image plane, Indicates the column direction of the virtual primary image plane.

[0048] Secondary image plane coordinate system: The coordinate system is in units of pixels. The origin is the principal point position, The direction is the row direction of the image sensor, The direction is the column direction of the image sensor.

[0049] Let the current time be At this time, the star in the star sensor coordinate system has a star vector First, it is projected on the virtual primary image plane through the image-side telecentric lens. The physical coordinates of the point where the star is projected on the virtual primary image plane are According to the projection position on the virtual primary image plane, the star passes through the micro-lens and micro-switch corresponding to the number for field gating, and then is projected on the secondary image plane through the rear-end magnifying objective lens for imaging, and the star point coordinates obtained are Similarly, the star has a star vector The physical coordinates of the point where the star is projected on the virtual primary image plane are The micro-lens with the number is used for field gating, and finally the star point coordinates on the secondary image plane are .

[0050] When the star sensor performs a small-angle rotation, it reaches time At time , the star vectors of the stars and in the star sensor coordinate system are and respectively, and the star point pixel coordinates on the secondary image plane are and respectively.

[0051] Step S100, calculate the displacement difference of the two star point coordinates on the secondary image plane before and after the motion.

[0052] From time to time , the star sensor performs a small-angle rotation. Assuming that during this motion process, the two stars are still within the field of view of the current micro-lens, the star point motion of the two stars on the secondary image plane is as shown in Figure 2

[0053] The displacement difference of the two star points on the secondary image plane in the direction is , and the displacement difference in the direction is The relationship is as follows: ​

[0054] (1)

[0055] According to the field-of-view gating imaging principle of the all-day star sensor, the physical coordinates of the star points on the virtual primary image plane are and the pixel coordinates of the star point on the secondary image plane There are the following relationships:

[0056] (2)

[0057] in, The coordinates of the principal point of the secondary image plane, is the magnification of the rear end magnifying lens, 、 is the pixel size of the image sensor, 、 is the physical coordinate of the microlens center on the virtual primary image plane.

[0058] Since the star sensor rotates at a small angle, At this moment, the projection point of the star on the virtual primary image plane is still at In the microlens at the moment, Figure 3 As shown:

[0059] Therefore, according to the above formulas (1) and (2), the displacement difference of the virtual primary image plane can be obtained: 、 The difference in displacement change from the secondary image plane of the star point 、 The relationship is as follows:

[0060] (3)

[0061] Step S200 , calculating the displacement difference between two star points on the virtual primary image plane before and after the movement.

[0062] According to the imaging principle of star sensors, stars Star Vector Its physical coordinates on the virtual primary image plane The relationship between them is as follows:

[0063] (4)

[0064] in is the primary image focal length.

[0065] like Figure 3 As shown, the stars From the moment Exercise to the moment , which is generated on the virtual primary image plane the displacement change of the direction and the displacement change of the direction As follows:

[0066] (5)

[0067] The motion of the star sensor from to can be decomposed into the superposition of the rotation of axis rotation , the rotation of axis rotation , and the rotation of axis rotation Therefore, according to the quaternion rotation formula and the principle of vector superposition, the star vector of the star at is as follows:

[0068] (6)

[0069] And according to the related parameters of the star sensor, the following constraints can be obtained:

[0070] 1. Since the star vector must be within the field of view (5° field of view) of the star sensor, there is:

[0071]

[0072] At the same time, since the star vector is a unit vector, there is:

[0073]

[0074] Then, by combining the above formulas, there is:

[0075] (7)

[0076] 2. When the star sensor rotates by a small angle, the decomposed rotation of axis rotation , the rotation of axis rotation , and the rotation of axis rotation should all be smaller than the field of view angle of the star sensor, so there is the following relationship:

[0077]

[0078]

[0079] Therefore, there is the following relationship:

[0080] (8)

[0081] In combination with formulas (6), (7), and (8), the following formula can be obtained:

[0082] (9)

[0083] Similarly, since the star sensor motion has a consistent effect on the two stars, the star The following formula can be obtained:

[0084] (10)

[0085] In combination with formulas (5), (9), and (10), the following formula can be obtained:

[0086] (11)

[0087] In step S300, the relative positional relationship between the star points is calculated based on the difference between the star point displacement amounts of the secondary image plane and the virtual primary image plane, and the star point dealiasing operation is performed.

[0088] In combination with formulas (3), (4), and (11), the following formula can be obtained:

[0089] (12)

[0090] According to formula (12), the relative positional relationship of the star points in the virtual primary image plane at time t2 can be determined based on the displacement amount of the star points in the secondary image plane between time t1 and time t2.

[0091] According to the positive and negative values of Δx, the following two kinds of relative positional relationship judgment bases can be obtained: 1. When Δx>0:

[0092]

[0093]

[0094] 2. When Δx<0:

[0095]

[0096] According to the above judgment bases, the relative positional relationship between the star points in the virtual primary image plane can be obtained. In combination with multiple relative positional relationships, the relative positional relationship of all star points in the virtual primary image plane can be obtained.

[0097] ​​​​​​Assume that there are three star points in the secondary image plane, respectively , , . According to the above steps, the relative position relationship of the star points in the virtual primary image plane in the previous frame can be obtained through the displacement amount relationship of the three star points in the secondary image plane in the adjacent two frames, as shown in Figure 4

[0098] Meanwhile, according to the opening and closing states of the micro switch of the star sensor at time , the field of view gating condition of the star sensor at time can be obtained, as shown in the following figure:

[0099] It can be seen that Figure 4 Figure 5 , the field of view gating condition of Figure 5 corresponds to the relative position relationship of the star points shown in Figure 4 (a), and therefore the matching diagram shown in the following figure can be obtained:

[0100] After obtaining the matching relationship diagram of Figure 6 , the one-to-one correspondence between the star points in the secondary image plane and the micro lens field of view is realized, and the function of star point dealiasing is realized. Subsequently, the attitude of the star sensor can be calculated according to the normal star map recognition process. Specific embodiments:

[0102] Figure 7 A field of view gating state diagram is generated for a simulation program, wherein the white area is the gating field of view corresponding to the opened micro switch.

[0103] Figure 8 (a) is the secondary image plane image corresponding to the star map shown in Figure 7 , and Figure 8 (b) is the secondary image plane image of the next frame.

[0104] According to the simulation star map shown in Figure 8 , the star point centroid positioning is performed, and the displacement amount difference between different star points in the two frames is calculated, and the following table can be obtained:

[0105] Table 1 Coordinate difference of star points in secondary image plane

[0106]

[0107] According to the method of the present application, the relative position relationship of the four star points 19, 42, 52 and 61 in the virtual primary image plane can be obtained, as shown in Figure 9

[0108] According to the relative position relationship of the star points shown in Figure 9 , the field of view gating condition of Figure 7 ​​The matching results are shown in FIG. 6. Figure 10

[0109] The actual virtual primary image surface in the simulation program is shown in FIG. 7. Figure 11

[0110] As shown in FIG. 8, there are four star points in the virtual primary image surface, and the star numbers are 19, 60, 61 and 52, 42. Figure 11 However, the star point of the star number 60 is at the edge of the gated field of view, so it cannot be imaged on the secondary image surface, and thus there is no image of the star point of the star number 60 on the secondary image surface.

[0111] By comparing FIG. 6 with FIG. 8, it is found that the matching results of the star points and the gated field of view are consistent with the actual virtual primary image surface in the simulation. Figure 10 Figure 11 Therefore, the method proposed in the application can correctly correspond the star points on the secondary image surface to the gated field of view, and achieve the purpose of de-mixing the star points.

[0112] The application also relates to an all-weather star sensor star point de-mixing system based on a field of view gating, which comprises:

[0113] A first displacement difference calculation module is configured to calculate the displacement difference of the coordinates of two star points on the secondary image surface before and after the movement of the star sensor.

[0114] A second displacement difference calculation module is configured to calculate the displacement difference of the coordinates of two star points on the virtual primary image surface before and after the movement of the star sensor.

[0115] A star point de-mixing module is configured to calculate the relative position relationship between the star points by combining the displacement differences of the star points on the secondary image surface and the virtual primary image surface, and perform a star point de-mixing operation.

[0116] The application also relates to an electronic device, which comprises:

[0117] at least one processor; and

[0118] a memory connected to the at least one processor in communication; wherein

[0119] the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method.

[0120] The application also relates to a non-transitory computer readable storage medium storing computer instructions for causing the computer to execute the method.

[0121] ​​​In summary, the application provides a kind of all-weather star sensor star point dealiasing method based on field of view strobe, comprising the following steps: step S100, the displacement difference of the coordinates of two star points in the two image planes before and after the motion of star sensor is calculated;Step S200, the displacement difference of the two star points on the virtual primary image plane before and after the motion of star sensor is calculated;Step S300, the relative position relationship between star points is calculated by combining the displacement difference of star points in the two image planes and the virtual primary image plane, and star point dealiasing operation is carried out.The application can realize star point dealiasing in a short time, make star points one-to-one corresponding with the strobe field of view, and the calculation method is simple, without multiple matching, the algorithm purpose can be realized, the real-time performance of algorithm can be guaranteed, and the calculation accuracy is higher.

[0122] It should be understood that the above specific embodiments of the application are only used for illustrative or explanatory purposes of the principles of the application, and do not constitute a limitation of the application. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the application shall be included in the protection scope of the application. In addition, the appended claims of the application are intended to cover all variations and modifications falling within the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.

Claims

1. A star point de-aliasing method for all-day star sensor based on field of view gating, characterized in that: The steps include: Step S100, calculating the displacement difference between the coordinates of two star points in the secondary image plane before and after the star sensor moves; Step S200, calculating the displacement difference between two star points on the virtual primary image plane before and after the star sensor moves; Step S300: Combine the star point displacement difference between the secondary image plane and the virtual primary image plane to calculate the relative position relationship between the star points and perform star point de-aliasing operation: Time has come The displacement of the star point on the secondary image plane between the times is determined The relative position relationship of the star points on the virtual primary image plane at each moment; obtaining the relative position relationship between multiple star points in the virtual primary image plane; combining multiple relative position relationships to obtain the relative position relationship of all star points in the virtual primary image plane; Assume that there are three star points in the secondary image plane, namely 、 、 , through the displacement relationship of the three star points on the secondary image plane in two adjacent frames, the relative position relationship of the star points in the previous frame on the virtual primary image plane is obtained. The opening and closing state of the micro switch of the star sensor is used to obtain the time When the star sensor field of view is selected, a matching relationship is obtained, so that the star points in the secondary image plane correspond one to one with the microlens field of view, and star point solver is realized.

2. The method according to claim 1, characterized in that The step S100 includes: Step S110, obtain the two star points on the secondary image plane The difference in displacement in the direction as well as The difference in displacement in the direction relationship; Step S120: According to the field-of-view gating imaging principle of the all-day star sensor, the physical coordinates of the star points on the virtual primary image plane are obtained. and the pixel coordinates of the star point on the secondary image plane relationship; Step S130: according to the two star points on the secondary image plane The difference in displacement in the direction as well as The difference in displacement in the direction and the physical coordinates of the virtual primary image star points and the pixel coordinates of the star point on the secondary image plane The relationship between the displacement of the image plane is obtained. 、 The difference in displacement change from the secondary image plane of the star point 、 relationship.

3. The all-day star sensor star point dealiasing method based on field of view gating according to claim 2, characterized in that: The step S200 includes: Step S210, get the star Star Vector Its physical coordinates on the virtual primary image plane the relationship between; Step S220, star From the moment Exercise to the moment , and obtain the value generated on the virtual primary image plane Displacement change in direction as well as Displacement change in direction ; Step S230: The star sensor is Time has come The motion of the moment is decomposed into Axis rotation , around Axis rotation , around Axis rotation Superposition of motion.

4. A star point de-aliasing system for a star sensor based on field of view gating at all times of the day, the system being based on the star point de-aliasing method for a star sensor based on field of view gating at all times of the day according to any one of claims 1 to 3, characterized in that: include: The first displacement difference calculation module is used to calculate the displacement difference of the coordinates of two star points in the secondary image plane before and after the star sensor moves; The second displacement difference calculation module is used to calculate the displacement difference between two star points on the virtual primary image plane before and after the star sensor moves; The star point de-aliasing module is used to combine the star point displacement difference between the secondary image plane and the virtual primary image plane, calculate the relative position relationship between the star points, and perform star point de-aliasing operations.

5. An electronic device, characterized in that: The electronic device comprises: at least one processor; and, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of the preceding claims 1 to 3. 6 . A non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the method according to claim 1 .

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