On-orbit antenna flatness measurement method and system based on two-dimensional PSD

Abstract

The invention provides an in-orbit antenna flatness measurement method and system based on a two-dimensional PSD, and the method comprises the steps: arranging the two-dimensional PSD and a surface scanning laser on a satellite antenna and a satellite body, and scanning the two-dimensional PSD through the surface scanning laser; supports with different heights are arranged according to the size of an included angle between a laser scanning line and a photosensitive surface; after the antenna displaces or deflects, the laser scanning track on the photosensitive surface is changed, at the moment, the output value of the PSD is collected, the offset or deflection of the single measuring point of the antenna is calculated, and the flatness of the single measuring point of the antenna is obtained; and calculating the overall flatness value of the antenna by combining the offset and the flatness value of the multiple measurement points, so as to realize real-time monitoring of the flatness of the on-orbit antenna. The measuring system is high in monitoring precision and dimensionality, and can measure the displacement of the antenna in the direction perpendicular to the surface, clockwise or anticlockwise deflection along a certain axis, compound displacement and the like.

Description

Technical Field

[0001] The present invention relates to the field of industrial measurement technology, and in particular to an on-orbit antenna flatness measurement method and system based on two-dimensional PSD. Background Art

[0002] Planar array SAR antenna is a common satellite antenna structure, which is widely used in civil and military fields. SAR antenna is composed of multiple panels. The overall flatness of the antenna after installation and deployment is a key indicator for antenna array design and installation, which directly affects antenna gain, sidelobe level, imaging quality, and beam pointing accuracy. Therefore, accurate measurement of antenna flatness is of great significance to the design and use of SAR systems, as well as the development of large-size, high-precision satellites.

[0003] Laser measurement systems have the characteristics of large scanning range, fast speed, high accuracy, and high degree of automation. They are often used to measure the antenna flatness of satellites in orbit at home and abroad. However, laser measurement systems are generally very complex. In order to ensure the measurement accuracy, a large number of sensors or measurement points need to be deployed, which makes the data processing and calculation process cumbersome. The system is prone to redundancy, making it difficult to optimize or modify. Therefore, a simple and reliable on-orbit antenna flatness real-time monitoring system with high measurement accuracy and dimension and a small number of channels is needed.

[0004] Patent document CN103983219A (application number: 201410249777.1) discloses a method for measuring the flatness of a large size. By deploying two laser trackers, the coordinates of the same point on the measured surface are measured, and the data is corrected by error compensation to calculate the flatness of the measured surface. This method requires the deployment of two laser trackers with a height difference, which is not suitable for measurement in limited space (such as satellites in orbit) and is mostly used for ground testing. The measurement method used in the present invention only requires a flat scanning laser, has a simple structure, can be used in ground and on-orbit environments, and has a wide range of applications.

[0005] Patent document CN104089594A (application number: 201410360762.2) discloses a SAR antenna automatic precision measurement method, which obtains the coordinates of satellite array surface marker points and public target sphere points through laser radar and theodolite, and obtains the antenna array surface flatness and normal direction through the conversion of the two coordinate systems. This method requires the arrangement of a large number of array surface marker points, and the system is highly complex and difficult to operate. However, the present invention only requires the arrangement of a few two-dimensional PSDs around the antenna, and the system is simple and reliable.

[0006] Patent document CN108168472A (application number: 201711291929.4) discloses a method for measuring the flatness of satellite antenna deployment. The dot-coded marks of the satellite substrate and antenna panel are measured by a photographic system, and the flatness of the satellite substrate and antenna panel is calculated after the digital image is processed. This method requires a mobile device equipped with a digital camera to scan the antenna panel and is only applicable to ground measurements. The present invention does not require additional mobile equipment, and flatness measurement can be performed after the station is deployed.

[0007] Patent document CN109631793A (application number: 201811520189.1) discloses a surface digital photography automated measurement method, which uses a laser tracker to measure the position and posture of the surface to be measured, and controls a robotic arm equipped with a digital camera to take pictures, and obtains the surface directivity and flatness through processing and analysis. This measurement method requires collaborative processing of multiple devices, and the system structure is complex, which is not suitable for on-orbit antenna measurement. The present invention is designed for on-orbit antenna flatness measurement, and has strong applicability for on-orbit measurement.

[0008] Patent document CN117214841A (application number: 202311203343.3) discloses a method for calibrating the plane of a phased array radar antenna. The array lobe pattern is synthesized by a wave control system, and the radiation field distribution of the array is reconstructed to calculate the antenna pointing and flatness. This method combines the calibration horn and the total station to improve the measurement accuracy, but the acoustic wave measurement is not suitable for a vacuum environment. The present invention uses a surface scanning laser to measure flatness, which is suitable for on-orbit antenna measurement environments. Summary of the invention

[0009] In view of the defects in the prior art, the object of the present invention is to provide a method and system for measuring the flatness of an on-orbit antenna based on two-dimensional PSD.

[0010] According to the present invention, a method for measuring the flatness of an on-orbit antenna based on two-dimensional PSD is provided, comprising:

[0011] Step S1: deploying a two-dimensional PSD and a surface scanning laser on a satellite antenna and a satellite body, and scanning the two-dimensional PSD by the surface scanning laser;

[0012] Step S2: setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface;

[0013] Step S3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained;

[0014] Step S4: By combining the offsets and flatness values ​​of multiple measurement points, the overall flatness value of the antenna is calculated to achieve real-time flatness monitoring of the on-orbit antenna.

[0015] Preferably, the on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and deployed;

[0016] Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24;

[0017] A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

[0018] Preferably, the surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes as the antenna flatness changes, thereby calculating the offset or deflection of the measurement position;

[0019] The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support;

[0020] The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

[0021] Preferably, in step S3:

[0022] Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole;

[0023] The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as:

[0024] Δz=H / D·Δy

[0025] Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as:

[0026]

[0027]

[0028] Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

[0029] Preferably, in step S4:

[0030] The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

[0031]

[0032]

[0033] According to the present invention, an on-orbit antenna flatness measurement system based on two-dimensional PSD is provided, comprising:

[0034] Module M1: deploy two-dimensional PSD and surface scanning laser on the satellite antenna and satellite body, and scan the two-dimensional PSD by the surface scanning laser;

[0035] Module M2: Setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface;

[0036] Module M3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained;

[0037] Module M4: Combines the offset and flatness values ​​of multiple measurement points to calculate the overall flatness value of the antenna, and realizes real-time flatness monitoring of the on-orbit antenna.

[0038] Preferably, the on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and deployed;

[0039] Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24;

[0040] A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

[0041] Preferably, the surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes as the antenna flatness changes, thereby calculating the offset or deflection of the measurement position;

[0042] The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support;

[0043] The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

[0044] Preferably, in the module M3:

[0045] Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole;

[0046] The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as:

[0047] Δz=H / D·Δy

[0048] Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as:

[0049]

[0050]

[0051] Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

[0052] Preferably, in the module M4:

[0053] The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

[0054]

[0055]

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. The present invention uses a small number of two-dimensional PSD stations, simplifies the system, and only 1-3 stations are required on the antenna board to achieve the overall measurement of the antenna flatness;

[0058] 2. The measurement method of the present invention realizes single module output. A single two-dimensional PSD can output the antenna flatness of a single measurement point, and multiple two-dimensional PSDs can output the overall flatness of the satellite antenna.

[0059] 3. The monitoring accuracy and dimension of the measurement system of the present invention are high, and it can measure the displacement of the antenna in the vertical surface direction, the clockwise or counterclockwise deflection along a certain axis, and the composite displacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0061] Figure 1 It is a schematic diagram of the station arrangement method of the two-dimensional PSD and laser on the surface of the on-orbit satellite in the measurement method of the present invention;

[0062] Figure 2 It is a schematic diagram of the two-dimensional PSD photosensitive surface structure and the laser scanning method in the measurement method of the present invention;

[0063] Figure 3 It is a schematic diagram of the installation method when the height difference between the two-dimensional PSD and the plane where the laser is located is different in the measurement method of the present invention;

[0064] Figure 4 A schematic diagram of the displacement of the laser scanning trajectory when the planar array SAR antenna is offset in the measurement method of the present invention;

[0065] Figure 5 It is a schematic diagram of the principle of calculating the flatness of the SAR antenna based on the two-dimensional PSD signal output in the measurement method of the present invention;

[0066] Figure 6 A structural flow chart of using the measurement system of the present invention to perform real-time monitoring of the flatness of an on-orbit planar array SAR antenna;

[0067] Among them, 1 is the two-dimensional PSD, 2 is the planar array antenna, 3 is the satellite body, 4 is the scanning laser, 5 is the photosensitive surface, 6 is the scanning track, 7 is the support, 8 is the satellite body, and 9 is the changed scanning track. DETAILED DESCRIPTION

[0068] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0069] Embodiment 1:

[0070] The present invention proposes a real-time measurement method for the flatness of an on-orbit planar array SAR antenna based on a two-dimensional PSD, which realizes real-time and high-precision antenna flatness measurement, and aims to simplify the laser measurement system while improving the effectiveness of single-point measurement. The method includes the following steps: arranging a two-dimensional PSD and a surface scanning laser on a satellite antenna and a satellite body, and there is a certain height difference between the planes where the two are located; scanning the two-dimensional PSD by a surface scanning laser, setting supports of different heights on the surface of the satellite antenna, and changing the angle between the laser scanning line and the photosensitive surface; when the antenna is displaced or deflected, the laser scanning trajectory of the photosensitive surface changes, and at this time, the output value of the two-dimensional PSD is collected, the offset or deflection of a single measurement point of the antenna is calculated, and the flatness of the single measurement point is output; the offset or deflection of multiple measurement points is combined to calculate the overall flatness of the antenna, and the real-time monitoring of the flatness of the on-orbit antenna is realized. The present invention uses a small number of two-dimensional PSD stations, a simplified system, and can realize single-module output or multi-module calculation of overall flatness, thereby monitoring the displacement, deflection or composite displacement of the antenna.

[0071] According to the present invention, a method for measuring the flatness of an on-orbit antenna based on two-dimensional PSD is provided, comprising:

[0072] Step S1: deploying a two-dimensional PSD and a surface scanning laser on a satellite antenna and a satellite body, and scanning the two-dimensional PSD by the surface scanning laser;

[0073] Step S2: setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface;

[0074] Step S3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained;

[0075] Specifically, in step S3:

[0076] Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole;

[0077] The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as:

[0078] Δz=H / D·Δy

[0079] Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as:

[0080]

[0081]

[0082] Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

[0083] Step S4: By combining the offsets and flatness values ​​of multiple measurement points, the overall flatness value of the antenna is calculated to achieve real-time flatness monitoring of the on-orbit antenna.

[0084] Specifically, in step S4:

[0085] The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

[0086]

[0087]

[0088] Specifically, the on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and unfolded;

[0089] Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24;

[0090] A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

[0091] Specifically, the surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes as the antenna flatness changes, thereby calculating the offset or deflection of the measurement position;

[0092] The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support;

[0093] The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

[0094] Embodiment 2:

[0095] Embodiment 2 is a preferred example of Embodiment 1, and is used to illustrate the present invention in more detail.

[0096] The present invention also provides an on-orbit antenna flatness measurement system based on two-dimensional PSD. The on-orbit antenna flatness measurement system based on two-dimensional PSD can be realized by executing the process steps of the on-orbit antenna flatness measurement method based on two-dimensional PSD, that is, those skilled in the art can understand the on-orbit antenna flatness measurement method based on two-dimensional PSD as a preferred implementation of the on-orbit antenna flatness measurement system based on two-dimensional PSD.

[0097] According to the present invention, an on-orbit antenna flatness measurement system based on two-dimensional PSD is provided, comprising:

[0098] Module M1: deploy two-dimensional PSD and surface scanning laser on the satellite antenna and satellite body, and scan the two-dimensional PSD by the surface scanning laser;

[0099] Module M2: Setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface;

[0100] Module M3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained;

[0101] Specifically, in the module M3:

[0102] Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole;

[0103] The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as:

[0104] Δz=H / D·Δy

[0105] Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as:

[0106]

[0107]

[0108] Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

[0109] Module M4: Combines the offset and flatness values ​​of multiple measurement points to calculate the overall flatness value of the antenna, and realizes real-time flatness monitoring of the on-orbit antenna.

[0110] Specifically, in the module M4:

[0111] The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

[0112]

[0113]

[0114] Specifically, the on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and unfolded;

[0115] Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24;

[0116] A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

[0117] Specifically, the surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes as the antenna flatness changes, thereby calculating the offset or deflection of the measurement position;

[0118] The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support;

[0119] The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

[0120] Embodiment 3:

[0121] Embodiment 3 is a preferred example of Embodiment 1, and is used to illustrate the present invention in more detail.

[0122] Figure 1 This is a schematic diagram of the deployment method of the two-dimensional PSD and the surface scanning laser on the surface of an on-orbit satellite. A real-time monitoring system for the flatness of an on-orbit satellite antenna is established. The system consists of a two-dimensional PSD1, a planar array antenna 2, a satellite body 3, and a surface scanning laser 4. The laser 4 is used to scan the PSD1 and calculate the antenna flatness.

[0123] The two-dimensional PSD1 is arranged around the planar array antenna 2, and the surface scanning laser is arranged on the surface of the satellite body 3, and there is a certain height difference between the plane where the PSD and the laser are located.

[0124] Among them, the number of PSD stations is 1-4 per board, the number of 2-segment antenna stations is 2-8, the number of 4-segment antenna stations is 4-16, the number of 6-segment antenna stations is 6-24, the number of 8-segment antenna stations is 8-32. The number of laser stations is 1-3.

[0125] Figure 2 The schematic diagram of the photosensitive surface 5 of the two-dimensional PSD1 and the laser scanning path 6 on its surface is shown in FIG. The photosensitive surface 5 is a symmetrical structure, including but not limited to a rectangle, a circle or other polygons. The laser scanning path 6 on the surface is two clusters of parallel lines perpendicular to each other, including but not limited to 3-9 scanning lines parallel to the X-axis direction and 3-9 scanning lines parallel to the Y-axis direction. The coordinate point position is read once every 0.1mm-3mm in a single scanning line. The interval can be determined according to the measurement accuracy requirements and the size of the photosensitive surface 5. The total number of coordinate points read for a single two-dimensional PSD1 is 20-150.

[0126] It is worth noting that this description is only an embodiment of the laser scanning path 6. According to the same principle, cross scanning lines, spiral scanning lines, zigzag scanning lines, etc. can be used. Therefore, the patent of the present invention does not limit the shape, number, crossover, etc. of the scanning path. Any implementation method that can achieve the same effect is within the scope of the present invention.

[0127] Figure 3 Schematic diagram of the installation method when the height difference between the two-dimensional PSD1 and the plane where the surface scanning laser 4 is located is different. When the length of the planar array antenna 2 and the height of the satellite body 3 are relatively suitable, a certain angle is formed between the laser scanning line and the photosensitive surface. The flatness of the antenna can be calculated by combining the angle and the displacement of the scanning line. When the length of the planar array antenna 2 is large or the height of the satellite body 8 is small, the angle between the laser scanning line and the photosensitive surface is small, which is not conducive to laser scanning and flatness calculation. Therefore, it is necessary to add a support 7 so that there is a certain angle between the two-dimensional PSD1 and the antenna 2, thereby increasing the angle between the laser scanning line and the photosensitive surface, which is conducive to the calculation of the antenna flatness.

[0128] It should be noted that whether the angle between the laser scanning line and the photosensitive surface, and the angle between the PSD and the antenna are appropriate is related to factors such as PSD sensitivity, laser positioning accuracy, and system algorithm. Therefore, the present invention does not limit the range of the angle. In addition, the present invention does not limit the specific implementation method of the support 7, including but not limited to an automatic lifting frame, a fixed frame, a rotating table, etc. Any implementation method that can achieve the same effect is within the scope of the present invention.

[0129] Figure 4 The figure is a schematic diagram of the displacement of the laser scanning track when the planar array SAR antenna is offset. Taking the upward displacement of the antenna perpendicular to the plane direction (Z axis) as an example, the PSD photosensitive surface 5 is displaced along the Z axis. At this time, the position of the original laser scanning track 6 on the photosensitive surface 5 changes to form a new scanning track 9, and the change mode of the parallel scanning lines is the same, so the complex scanning lines on the photosensitive surface 5 can reflect the same change trend. Similarly, this method can be used to determine the downward displacement of the antenna along the Z axis, the clockwise deflection along the OX axis, the counterclockwise deflection along the OX axis, the clockwise deflection along the OY axis, the counterclockwise deflection along the OY axis, and the composite deflection or displacement.

[0130] The principle of calculating the flatness of SAR antenna based on two-dimensional PSD signal output is as follows: Figure 5 As shown. The height of the surface scanning laser 4 from the horizontal plane where the satellite antenna 2 is located is H, and the horizontal distance from the two-dimensional PSD1 is D. The two-dimensional PSD1 is placed horizontally on the surface of the satellite antenna 2, and the angle between its photosensitive surface 5 and the incident laser is θ. Taking the antenna offset along the positive direction of the Z axis as an example, the PSD photosensitive surface 5 is also offset along the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y-axis direction of the PSD photosensitive surface 5, and the offset of the measurement position along the Z axis is expressed as:

[0131] Δz=H / D·Δy,

[0132] By calculating the offset of multiple scan lines within a single PSD photosensitive surface, the flatness σ0 of a single measurement point can be obtained, which is expressed as:

[0133]

[0134]

[0135] Where m is the number of laser scan lines in the photosensitive surface, and zavg is the average offset of multiple scan lines in a single PSD photosensitive surface.

[0136] Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface can be obtained, which is expressed as:

[0137]

[0138]

[0139] Where n is the total number of two-dimensional PSDs on the antenna surface, and △Z is the offset of a single PSD, which is equivalent to the average offset of multiple scan lines in the photosensitivity surface of a single PSD.

[0140] At this time, the overall flatness σ of the satellite antenna can be expressed as:

[0141]

[0142] When the angle between the laser scanning line and the photosensitive surface is small, the support is used to tilt the PSD photosensitive surface so that the angle between it and the horizontal plane of the antenna is α. At this time, the angle between the laser scanning line and the PSD photosensitive surface can be expressed as:

[0143] θ=arctan(H / D)+α,

[0144] At this time, the offset of the antenna measurement position along the Z axis can be expressed as:

[0145] Δz=Δy·tanθ / cosα=Δy·tanθ·secα,

[0146] Similarly, the value of the overall flatness of the antenna can be calculated by combining the offsets of multiple two-dimensional PSD measurement points.

[0147] It should be noted that the above calculation method is only an implementation example of a single case. For clockwise or counterclockwise deflection along a certain axis and composite displacement, targeted data processing and analysis are required to obtain an accurate value of the overall flatness of the antenna.

[0148] The structural process of the on-orbit planar array SAR antenna flatness real-time measurement system is as follows: Figure 6As shown. First, two-dimensional PSDs and surface scanning laser transmitters are deployed on the satellite antenna and the fuselage, and there is a certain height difference between the planes where the two are located. After that, preliminary error calibration is carried out on the ground, the output values ​​of each two-dimensional PSD are collected, and the single measurement point of the antenna and the overall flatness are calculated. After the satellite is launched into orbit, a secondary calibration of the on-orbit antenna flatness is carried out to collect data and calculate again. If the flatness value is within a reasonable range, the current antenna condition is maintained and the current system monitoring results are fed back; if the flatness value is too large, the antenna position needs to be adjusted through the actuator, and the current antenna condition is judged in combination with multi-channel signals, and the system monitoring results before and after the adjustment are fed back, and continuous monitoring is carried out.

[0149] It should be noted that the determination range of the numerical value of the antenna flatness is related to the size of the SAR antenna. The more arrays there are and the larger the size is, the greater the tolerance for antenna flatness is; the smaller the size is, the higher the requirement for flatness is. Therefore, the present invention does not limit the determination range of the numerical value of the flatness.

[0150] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0151] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for measuring the flatness of an on-orbit antenna based on two-dimensional PSD, characterized in that: include: Step S1: deploying a two-dimensional PSD and a surface scanning laser on a satellite antenna and a satellite body, and scanning the two-dimensional PSD by the surface scanning laser; Step S2: setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface; Step S3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained; Step S4: By combining the offsets and flatness values ​​of multiple measurement points, the overall flatness value of the antenna is calculated to achieve real-time flatness monitoring of the on-orbit antenna.

2. The on-orbit antenna flatness measurement method based on two-dimensional PSD according to claim 1, characterized in that: in, The on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and deployed; Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24; A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

3. The on-orbit antenna flatness measurement method based on two-dimensional PSD according to claim 1, characterized in that: The surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes with the change of the antenna flatness, thereby calculating the offset or deflection of the measurement position; The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support; The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

4. The on-orbit antenna flatness measurement method based on two-dimensional PSD according to claim 1, characterized in that: In step S3: Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole; The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as: Δz=H / D·Δy Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as: Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

5. The on-orbit antenna flatness measurement method based on two-dimensional PSD according to claim 1, characterized in that: In step S4: The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

6. An on-orbit antenna flatness measurement system based on two-dimensional PSD, characterized in that: include: Module M1: deploy two-dimensional PSD and surface scanning laser on the satellite antenna and satellite body, and scan the two-dimensional PSD by the surface scanning laser; Module M2: Setting supports of different heights according to the angle between the laser scanning line and the photosensitive surface; Module M3: After the antenna is displaced or deflected, the laser scanning trajectory on the photosensitive surface changes. At this time, the PSD output value is collected, the offset or deflection of the single measurement point of the antenna is calculated, and the flatness of the single measurement point of the antenna is obtained; Module M4: Combines the offset and flatness values ​​of multiple measurement points to calculate the overall flatness value of the antenna, and realizes real-time flatness monitoring of the on-orbit antenna.

7. The on-orbit antenna flatness measurement system based on two-dimensional PSD according to claim 6, characterized in that: in, The on-orbit planar array antenna is composed of 2 to 8 SAR antenna panels installed on the satellite body and deployed; Among them, the number of 2D PSD stations is 1 to 3 per board, the number of 2-segment antenna stations is 4 to 6, the number of 4-segment antenna stations is 6 to 12, the number of 6-segment antenna stations is 8 to 18, and the number of 8-segment antenna stations is 10 to 24; A two-dimensional PSD is installed around the planar array antenna, a surface scanning laser is installed on the surface of the satellite body, and there is a preset height difference between the plane where the two-dimensional PSD and the surface scanning laser are located.

8. The on-orbit antenna flatness measurement system based on two-dimensional PSD according to claim 6, characterized in that: The surface scanning laser performs laser scanning on the photosensitive surface of the two-dimensional PSD, and the scanning trajectory changes with the change of the antenna flatness, thereby calculating the offset or deflection of the measurement position; The angle between the photosensitive surface and the scanning line of the surface scanning laser is increased by adding a support; The scanning mode of the surface scanning laser is parallel line scanning, cross line scanning or spiral line scanning, covering the sensing area of ​​the photosensitive surface.

9. The on-orbit antenna flatness measurement system based on two-dimensional PSD according to claim 6, characterized in that: In the module M3: Based on the offset of the measurement position, calculating the average offset, the single-point flatness of the measurement point, and the flatness of the antenna as a whole; The height of the surface scanning laser from the horizontal plane where the satellite antenna is located is H, and the horizontal distance from the two-dimensional PSD is D. The two-dimensional PSD is placed horizontally on the surface of the satellite antenna, and the angle between its photosensitive surface and the incident laser is θ. The antenna is offset in the positive direction of the Z axis, and the PSD photosensitive surface is offset in the positive direction of the Z axis. At this time, the laser scanning trajectory appears to be displaced Δy along the Y axis direction of the PSD photosensitive surface. The offset of the measurement position along the Z axis is expressed as: Δz=H / D·Δy Combining the data collected from multiple 2D PSD measurement points, the average offset of the 2D PSD on the antenna surface is obtained, which is expressed as: Where Δz is the offset of a single scan line in the photosensitive surface, ΔZ is the offset of a single measurement position in the measurement system, m is the total number of scan lines in the photosensitive surface, n is the total number of stations on the two-dimensional PSD of the antenna surface, and z avg is the average offset of the scan line in a single PSD photosensitive surface, Z avg is the average offset of the two-dimensional PSD on the antenna surface.

10. The on-orbit antenna flatness measurement system based on two-dimensional PSD according to claim 6, characterized in that: In the module M4: The calculation method of the single measurement point flatness σ0 and the antenna overall flatness σ is expressed as:

Images