A real-time calibration method for an antenna profile rapid measurement system

Abstract

The application discloses a kind of antenna profile rapid measurement system real-time calibration method, comprising: each laser tracker respectively to each control point is aimed at ranging, the distance value of each laser tracker center and each control point is obtained, create space sphere, obtain the accurate coordinate of each control point;Antenna profile rapid measurement system is photographed to the control point and the measured mark point of measured antenna imaging, the image point coordinate of control point and the image point coordinate of the measured mark point of measured antenna are obtained;Based on control point collinear condition equation and the preset measurement camera internal parameter, the position and posture of control point relative to control field coordinate system are obtained according to the image point coordinate of control point and the image point coordinate of the measured mark point of measured antenna;According to profile measurement point collinear equation and the position and posture of control point relative to control field coordinate system, the position and posture of the measured mark point of measured antenna are obtained.The application improves the measurement accuracy and reliability of antenna profile rapid measurement system.

Description

Technical Field

[0001] This invention belongs to the field of antenna mechanical measurement technology, and in particular relates to a real-time calibration method for a rapid antenna profile measurement system. Background Technology

[0002] Large mesh antennas consist of complex cable-net structures, characterized by their large size, flexibility, and non-fixed profile. In the development of umbrella-shaped and ring-shaped antennas, the initial reflector profile accuracy is inevitably insufficient after the metal mesh is laid and sewn onto the rope truss structure. Generally, the tension ropes are used to adjust and ensure the profile accuracy. Due to the large size and high profile accuracy requirements of large mesh antennas, and the fact that a single antenna typically has hundreds or thousands of adjustment points, with each point's adjustment affecting the shape of the surrounding mesh through coupling, profile adjustment is an iterative, gradual, time-consuming, and labor-intensive process. Continuous measurement is required throughout the adjustment phase to provide real-time quantitative guidance. Ultimately, through multiple cycles of "profile accuracy measurement – ​​profile accuracy adjustment," the profile accuracy of the large mesh antenna meets high-precision design requirements, ensuring the final beam pointing and gain of the antenna.

[0003] With the accelerating pace of space missions, the current six-month measurement and adjustment cycle for a large mesh antenna is no longer sufficient to meet product development needs. Therefore, to improve the efficiency of large mesh antenna surface adjustment, the process technology group of the Antenna Assembly and Integration Testing Center at the Space Antenna Technology Research Institute of the Xi'an Branch, based on major space projects such as my country's lunar exploration, global mobile communication, and BeiDou navigation, and considering the characteristics and key technical requirements of large mesh antenna surface adjustment, has conducted research and development on rapid measurement technologies to shorten the adjustment time during the development process. Facing the continuously increasing aperture of mesh antennas, based on photogrammetry principles, a dedicated rapid measurement system for umbrella antennas and ring antennas has been established using a network of multiple fixed-station measurement cameras. Figure 1 As shown, its measurement coverage reaches XXm, and it transforms the traditional single-camera manual measurement process of mesh antenna surface accuracy into a multi-camera one-click rapid measurement, reducing the single measurement time from the original 40 minutes to 2 minutes, effectively solving the problem of high-efficiency measurement of large mesh antenna surface accuracy.

[0004] However, as the performance requirements for spaceborne antennas continue to increase and their operating frequencies rise, the accuracy of the reflector also needs to be further improved. For example, the Viasat-3 Americas satellite recently launched by the United States uses a loop antenna with a diameter of about 20m and an operating frequency in the Ka band. The surface accuracy of the reflector is better than 0.5mm. Therefore, in order to improve the measurement efficiency by using the above-mentioned rapid surface measurement system, it is even more necessary to meet the high-precision measurement requirements in the development process of large-size mesh antennas.

[0005] Currently, rapid antenna profile accuracy measurement systems can meet the measurement requirements of 0.5mm accuracy for XXm mesh antennas and 0.2mm accuracy for XXm mesh antennas. However, they cannot meet the measurement requirements of numerous subsequent Ka-band and above mesh antenna profiles. A single-camera manual photogrammetry method must be used. Although its measurement accuracy is very high, its measurement efficiency is far lower than that of rapid profile measurement systems. The key factor affecting measurement efficiency lies in the acquisition of multi-angle and multi-directional measurement photos. The traditional single-camera measurement method relies on a high-altitude work vehicle and the operator to move the camera and acquire measurement photos in sequence. Finally, the antenna profile accuracy is calculated by integrating all the photos. For the measurement of large mesh antennas, this method is time-consuming. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a real-time calibration method for a rapid antenna profile measurement system, thereby improving the measurement accuracy and reliability of the rapid antenna profile measurement system.

[0007] The objective of this invention is achieved through the following technical solution: a real-time calibration method for a rapid antenna profile measurement system, comprising: setting up multiple control points in the ground area corresponding to the area where the antenna under test is located, forming a three-dimensional control field; setting the rapid antenna profile measurement system above the antenna under test; wherein, multiple measuring cameras constitute the rapid antenna profile measurement system; multiple laser trackers are set at the boundary of the three-dimensional control field, and the position and attitude relationship between each laser tracker is obtained by networking multiple laser trackers through directional points; each laser tracker aims and measures the distance between the center of each laser tracker and each control point, creating a spatial sphere, and obtaining the precise three-dimensional coordinates of each control point by intersecting the spatial spheres; the rapid antenna profile measurement system photographs the control points and the measured marker points of the antenna under test, obtaining the image coordinates of the control points and the image coordinates of the measured marker points of the antenna under test;

[0008] Based on the collinearity condition equation of the control points and the preset intrinsic parameters of the measuring camera, the position and attitude of the measuring camera relative to the control field coordinate system are obtained according to the image point coordinates and three-dimensional precise coordinates of the control points.

[0009] The three-dimensional coordinates of the measured marker points of the antenna under test are obtained based on the collinearity equation of the surface measurement points and the position and attitude of the measuring camera relative to the control field coordinate system.

[0010] In the above-mentioned real-time calibration method for rapid antenna profile measurement system, multiple control points include multiple ground control points and multiple high-level control points. Specifically, multiple ground control points are set up in the ground area corresponding to the area where the antenna under test is located, and multiple high-level control points are set up in the ground area using a bracket support method. The multiple ground control points and multiple high-level control points form a three-dimensional control field.

[0011] In the above-mentioned real-time calibration method for rapid antenna profile measurement system, in the three-dimensional control field, the length, width, and height of the envelope formed by all control points are equal to the length, width, and height of the area where the antenna under test is located. Each measuring camera's field of view covers ≥3 control points, and there are no common control points between the measuring cameras.

[0012] In the above-mentioned real-time calibration method for the rapid antenna profile measurement system, the control point is a hemispherical structure with a circular fluorescent target pasted at the center of the hemispherical structure; the control point is adsorbed and placed in a magnetic base, with the circular fluorescent target facing the reference surface of the rapid antenna profile measurement system.

[0013] In the real-time calibration method of the above-mentioned rapid antenna profile measurement system, the diameter of the circular fluorescent target is obtained by the following formula:

[0014]

[0015] Where D is the diameter of the circular fluorescent target, L is the measurement distance, N is the number of pixels, P is the pixel size of the measuring camera, and f is the camera focal length.

[0016] In the above-mentioned real-time calibration method for rapid antenna profile measurement system, the method of networking multiple laser trackers by using directional points to obtain the position and attitude relationship between each laser tracker includes: based on the spatial coordinate values ​​of the directional point at the same location in the instrument coordinate system of each laser tracker, the position and attitude relationship between each laser tracker is obtained through joint adjustment calculation.

[0017] In the real-time calibration method of the above-mentioned rapid antenna profile measurement system, the orientation point is a 1.5-inch angular dipole spherical prism. The orientation point is set at several control point locations selected from multiple control point setting positions.

[0018] In the real-time calibration method of the above-mentioned rapid antenna profile measurement system, the precise three-dimensional coordinates of each control point are obtained by the following formula:

[0019]

[0020]

[0021] ...

[0022]

[0023] Among them, X LM Let X be the X coordinate of the Mth control point, and Y be the Y coordinate of the Mth control point. LM Let Y be the Y coordinate of the Mth control point, and Z be the Z coordinate of the Mth control point. LM Let X be the Z-coordinate of the Mth control point, R1 be the distance between the 1st laser tracker and the Mth control point, and X be the distance between the 1st laser tracker and the Mth control point. L2 Let X and Y be the coordinates of the center of the second laser tracker in the online measurement coordinate system. L2 Let Z be the Y-coordinate of the center of the second laser tracker in the online measurement coordinate system. L2 R2 is the Z-coordinate of the center of the second laser tracker in the online measurement coordinate system, and R2 is the distance between the second laser tracker and the Mth control point. LQ Let X be the center of the Q-th laser tracker in the online measurement coordinate system, and Y be the coordinates of its position. LQ Let Z be the Y-coordinate of the center of the Q-th laser tracker in the online measurement coordinate system. LQ Let R be the Z-coordinate of the center of the Q-th laser tracker in the online measurement coordinate system. Q Let Q be the distance between the Q-th laser tracker and the M-th control point.

[0024] In the real-time calibration method of the above-mentioned rapid antenna profile measurement system, the collinearity condition equation of control points is obtained by the following formula:

[0025]

[0026]

[0027] Among them, X LM Let X be the X coordinate of the Mth control point, and Y be the Y coordinate of the Mth control point. LM Let Y be the Y coordinate of the Mth control point, and Z be the Z coordinate of the Mth control point. LM Let f be the Z-coordinate of the Mth control point. j To measure the focal length of the camera for the j-th camera, X Sj Let X and Y be the coordinates of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let Z be the Y-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let a be the Z-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. 1j a 2j a 3j b 1j b 2j b 3j c 1j c 2j c 3jNine parameters are used to form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system. j is the measurement camera number, Δx is the image point x-bias, Δy is the image point y-bias, x is the image point abscissa, y is the image point ordinate, k1, k2 and k3 are radial distortion coefficients, r is the image point radial direction, p1 and p2 are eccentric distortion parameters, and b1 and b2 are image plane distortion parameters.

[0028] In the real-time calibration method of the above-mentioned rapid antenna profile measurement system, the collinearity equation of the profile measurement points is obtained by the following formula:

[0029]

[0030]

[0031] Among them, X i Let X and Y be the coordinates of the i-th measured marker point of the antenna under test in the online measurement coordinate system. i Let f be the Y-coordinate of the i-th measured marker point of the antenna under test in the online measurement coordinate system. j To measure the focal length of the camera for the j-th camera, X Sj Let X and Y be the coordinates of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let Z be the Y-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let a be the Z-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. 1j a 2j a 3j b 1j b 2j b 3j c 1j c 2j c 3j Nine parameters are used to form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system. i is the measured marker point number of the antenna under test, j is the measurement camera number, Δx is the image point x-bias, Δy is the image point y-bias, x is the image point abscissa, y is the image point ordinate, k1, k2 and k3 are radial distortion coefficients, r is the image point radial direction, p1 and p2 are eccentric distortion parameters, and b1 and b2 are image plane distortion parameters.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) This invention solves the problems of general external parameter calibration methods and measurement processes being carried out in steps, having poor real-time performance, low efficiency, and being unable to avoid the influence of environmental changes such as vibration on calibration accuracy.

[0034] (2) The three-dimensional solid structure and the large-scale control point design method that matches the size of the product being measured adopted in this invention solve the problem of insufficient control constraints on the measurement accuracy of three-dimensional, large-size products after the absolute orientation is completed by using a one-dimensional, short-length reference ruler during the system calibration process.

[0035] (3) The present invention provides a method for measuring control points by connecting multiple trackers in a laser tracker rangefinding mode, which improves the measurement and calibration accuracy of large-scale three-dimensional control points on site. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0037] Figure 1 This is a schematic diagram of a rapid measurement system for the profiles of umbrella antennas and loop antennas, which uses multiple fixed-station measuring cameras connected in a network in the existing technology.

[0038] Figure 2 This is a diagram of the real-time on-site calibration system provided in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the control point structure provided in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of control point coordinate measurement based on laser tracker ranging method provided in an embodiment of the present invention. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Figure 2 This is a diagram of the real-time on-site calibration system provided in an embodiment of the present invention. Combined with... Figure 2 The real-time calibration method for this rapid antenna profile measurement system includes:

[0043] (1) Multiple control points are set up in the ground area corresponding to the area where the antenna under test is located, and the multiple control points form a three-dimensional control field; the antenna profile rapid measurement system is set up above the antenna under test; multiple measuring cameras constitute the antenna profile rapid measurement system; the multiple control points include multiple ground control points and multiple high-level control points, wherein multiple ground control points are set up in the ground area corresponding to the area where the antenna under test is located, and multiple high-level control points are set up in the ground area using a bracket support method, and the multiple ground control points and multiple high-level control points form a three-dimensional control field.

[0044] (2) Multiple laser trackers are set at the boundary of the three-dimensional control field, and the position and attitude relationship between each laser tracker is obtained by the method of networking multiple laser trackers from the orientation point.

[0045] (3) Each laser tracker aims and measures the distance between the center of each laser tracker and each control point to obtain the distance value between the center of each laser tracker and each control point. A spatial sphere is created, and the precise coordinates of each control point are obtained by intersecting the spatial spheres.

[0046] (4) The rapid antenna profile measurement system takes pictures of the control point and the measured marker point of the antenna under test. After image scanning, it simultaneously obtains the image point coordinates of the control point and the image point coordinates of the measured marker point of the antenna under test.

[0047] (5) Based on the collinearity condition equation of the control points and the preset intrinsic parameters of the measuring camera, the coordinate system O of the control points relative to the control field coordinate system, i.e., the multi-tracker online measurement coordinate system, is obtained according to the image coordinates of the control points and the image coordinates of the measured marker points of the measured antenna. L X L Y L Z L Position and attitude. Based on the collinearity condition equations of photogrammetry and the corresponding camera intrinsic parameters, single-image space resection is used to calculate the position and attitude relative to the control field coordinate system, using the mathematical relationship between a certain number of control points and their corresponding image points within each station's photograph. This completes the synchronous orientation.

[0048] (6) The position and attitude of the measured marker points of the antenna under test are obtained based on the collinearity equation of the measurement points on the antenna profile and the position and attitude of the control points relative to the control field coordinate system. Specifically, based on the forward intersection principle of photogrammetry, the coordinates (X, X) of the antenna profile measurement points are synchronously calculated from the collinearity equation using the orientation parameters. i Y i Z i The entire process involves real-time orientation and measurement.

[0049] In step (1), M1 (M1≥3) control points are uniformly arranged on the ground of the entire area directly below the antenna of the antenna of the rapid measurement system composed of j (j≥2) multi-cameras to form a two-dimensional planar control field. At the same time, M2 (M2≥3) high-level control points are uniformly arranged using a support bracket. Finally, all control points form a three-dimensional, large-scale control field.

[0050] The three-dimensional, large-scale control field formed in step (1) is as follows: the length, width and height of the envelope formed by all control points are comparable to the size of the mesh antenna under test, each camera's field of view covers ≥3 control points, and there is no need for common points between cameras.

[0051] The control points used by the tracker in step (1) are specifically:

[0052] (3.1) The structure is designed as a 1.5-inch hemisphere, with a circular fluorescent target attached to the center of the hemisphere;

[0053] (3.2) The diameter D of the fluorescent target is determined by the number of pixels N, the camera pixel size P, the camera focal length f, the measurement distance L, etc., and the number of pixels N≥4;

[0054]

[0055] Where D is the diameter of the fluorescent target (mm); Lm is the measurement distance (m); N is the number of pixels; Pum is the camera pixel size (um); and fmm is the camera focal length (mm).

[0056] (3.3) The hemispherical control point is adsorbed and placed in a stable magnetic base, with the fluorescent target surface facing the reference surface of the rapid surface measurement system.

[0057] In step (2), k (k≥3) trackers are evenly distributed around the three-dimensional control field. Network optimization is achieved through orientation points, and a coordinate system O for online measurement of multiple trackers is established. L X L Y L Z L That is, to control the field coordinate system and obtain the position and attitude relationship between each tracker.

[0058] The method for networking k trackers using directional points in step (2) includes the following steps:

[0059] (4.1) Based on the orientation point at the same location, the coordinate system of the Q (Q=1~k) tracking instruments (O) LQ X LQ Y LQ Z LQThe spatial coordinate values ​​under ) are used to calculate the transformation relationship between the instrument coordinate systems of each pair of the Q-stage tracker, i.e. the position and attitude relationship, through joint adjustment.

[0060] (4.2) Based on the transformation relationship between the coordinate systems of the instruments in the Q trackers, a multi-tracker online measurement coordinate system O can be established with the coordinate system of the first tracker as the reference. L X L Y L Z L The coordinates of the center of the first tracker in the online measurement coordinate system are (0, 0, 0), and the coordinates of the center of the Qth (Q≠1) tracker in the online measurement coordinate system are (X... LQ Y LQ Z LQ ).

[0061] In step (3), k trackers aim and measure the distance to the same control point, obtaining k different distance values ​​(R1, R2, ..., Rk); using the center of each tracker and the distance values ​​measured for the corresponding control point, a spatial sphere is created, and the precise coordinates (X, Y, X) of the control point are obtained by intersecting the spatial spheres. LM Y LM Z LM ).

[0062] In step (3), the precise coordinates of each control point are obtained using the following formula:

[0063]

[0064]

[0065] ...

[0066]

[0067] Among them, X LM Let X be the X coordinate of the Mth control point, and Y be the Y coordinate of the Mth control point. LM Let Y be the Y coordinate of the Mth control point, and Z be the Z coordinate of the Mth control point. LM Let X be the Z-coordinate of the Mth control point, R1 be the distance between the 1st laser tracker and the Mth control point, and X be the distance between the 1st laser tracker and the Mth control point. L2 Let X and Y be the coordinates of the center of the second laser tracker in the online measurement coordinate system. L2 Let Z be the Y-coordinate of the center of the second laser tracker in the online measurement coordinate system. L2 R2 is the Z-coordinate of the center of the second laser tracker in the online measurement coordinate system, and R2 is the distance between the second laser tracker and the Mth control point. LQ Let X be the center of the Q-th laser tracker in the online measurement coordinate system, and Y be the coordinates of its position. LQLet Z be the Y-coordinate of the center of the Q-th laser tracker in the online measurement coordinate system. LQ Let R be the Z-coordinate of the center of the Q-th laser tracker in the online measurement coordinate system. Q Let M be the distance between the Q-th laser tracker and the M-th control point, where M = 1 to M1 + M2.

[0068] In step (2), the orientation point structure is a 1.5-inch angular dipole spherical prism, and ≥3 positions can be selected from the control points.

[0069] In step (5), the collinearity condition equation for the control points is obtained through the following formula:

[0070]

[0071]

[0072] Among them, X LM Let X be the X coordinate of the Mth control point, and Y be the Y coordinate of the Mth control point. LM Let Y be the Y coordinate of the Mth control point, and Z be the Z coordinate of the Mth control point. LM Let f be the Z-coordinate of the Mth control point. j To measure the focal length of the camera for the j-th camera, X Sj Let X and Y be the coordinates of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let Z be the Y-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let a be the Z-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. 1j a 2j a 3j b 1j b 2j b 3j c 1j c 2j c 3j Nine parameters are used to form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system. j is the measurement camera number, Δx is the image point x-bias, Δy is the image point y-bias, x is the image point abscissa, y is the image point ordinate, k1, k2 and k3 are radial distortion coefficients, r is the image point radial direction, p1 and p2 are eccentric distortion parameters, and b1 and b2 are image plane distortion parameters.

[0073] In step (6), the collinearity equation of the measuring points on the profile is obtained by the following formula:

[0074]

[0075]

[0076] Among them, X i Let X and Y be the coordinates of the i-th measured marker point in the online measurement coordinate system.i Let f be the Y-coordinate of the i-th measured marker point in the online measurement coordinate system. j To measure the focal length of the camera for the j-th camera, X Sj Let X and Y be the coordinates of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let Z be the Y-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. Sj Let a be the Z-coordinate of the center of the j-th measuring camera lens in the online measurement coordinate system. 1j a 2j a 3j b 1j b 2j b 3j c 1j c 2j c 3j Nine parameters are used to form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system. i is the measured marker point number of the antenna under test, j is the measurement camera number, Δx is the image point x-bias, Δy is the image point y-bias, x is the image point abscissa, y is the image point ordinate, k1, k2 and k3 are radial distortion coefficients, r is the image point radial direction, p1 and p2 are eccentric distortion parameters, and b1 and b2 are image plane distortion parameters.

[0077] The following is a detailed explanation using a specific example:

[0078] (1) such as Figure 2 As shown, M1 (M1≥3) control points are uniformly arranged on the ground in the entire area directly below the antenna under test of the antenna of the rapid antenna profile measurement system composed of j (j≥2) multi-cameras to form a two-dimensional planar control field. At the same time, M2 (M2≥3) high-level control points are uniformly arranged using a bracket support method. Finally, all control points form a three-dimensional, large-scale control field.

[0079] The three-dimensional, large-scale control field is specifically defined as follows: the envelope dimensions of all control points in length, width, and height are comparable to the size of the mesh antenna under test, each camera's field of view covers ≥3 control points, and there is no need for common points between cameras.

[0080] The control points are specifically as follows: Figure 3 As shown:

[0081] (a) The structure is designed as a 1.5-inch hemisphere, with a circular fluorescent target attached to the center of the hemisphere;

[0082] (b) The diameter D of the fluorescent target is determined by the number of pixels N, the camera pixel size P, the camera focal length f, the measurement distance L, etc., and the number of pixels N≥4;

[0083]

[0084] (c) The hemispherical control point is adsorbed and placed in a stable magnetic base, with the fluorescent target surface facing the reference surface of the rapid surface measurement system.

[0085] (2) k trackers (k≥3) are evenly distributed around the three-dimensional control field. Network optimization is achieved through orientation points, and a coordinate system O for online measurement of multiple trackers is established. L X L Y L Z L And obtain the position and attitude relationship between each tracker;

[0086] The method for networking k tracking devices using directional points includes the following steps:

[0087] (a) Based on the orientation point at the same location, in the coordinate system (O) of the Q (Q=1~k) tracking instruments. LQ X LQ Y LQ Z LQ The spatial coordinate values ​​under ) are used to calculate the transformation relationship between the instrument coordinate systems of each pair of the Q-stage tracker, i.e. the position and attitude relationship, through joint adjustment.

[0088] (b) Based on the transformation relationship between the coordinate systems of the instruments in the Q trackers, a multi-tracker online measurement coordinate system O can be established with the coordinate system of the first tracker as the reference. L X L Y L Z L The coordinates of the center of the first tracker in the online measurement coordinate system are (0, 0, 0), and the coordinates of the center of the Qth (Q≠1) tracker in the online measurement coordinate system are (X... LQ Y LQ Z LQ ).

[0089] The orientation points are specifically: a 1.5-inch angular dipole spherical prism, which can be selected at ≥3 locations from the control points.

[0090] (3) K tracking instruments aim and measure the distance to the same control point, obtaining k different distance values ​​(R1, R2, ..., Rk). Using the center of each tracking instrument and the distance values ​​measured for the corresponding control point, a spatial sphere is created. The precise coordinates (X, Y, X) of the control point are obtained by intersecting the spatial spheres. LM Y LM Z LM ),like Figure 4 As shown;

[0091] The control point is specifically a 1.5-inch angular dipole spherical prism, which shares a magnetic base with the control point described in step (1), and the two control point structures are concentric.

[0092] The coordinates of the control point (X) LM Y LM Z LM (M = 1 to M1 + M2) is calculated as follows:

[0093]

[0094]

[0095] ...

[0096]

[0097] (4) In the rapid antenna profile measurement system, multiple cameras at fixed stations photograph and image the control points and the measured marker points of the antenna product, respectively. After image scanning, the control points (x) are acquired synchronously. LMj y LMj ) and the image point coordinates (x) of the antenna profile measurement points ij y ij );

[0098] (5) Based on the collinearity condition equation of photogrammetry and the corresponding camera intrinsic parameters, single-image space resection is used to solve the mathematical relationship between a certain number of control points and their corresponding image points in the photographs of each station, and the position and attitude of the control field coordinate system are solved synchronously to complete the synchronous orientation.

[0099] The equation for the collinearity of the control points is:

[0100]

[0101]

[0102] (6) Based on the principle of forward intersection in photogrammetry, the coordinates of the antenna profile measurement points (X) are simultaneously calculated using the collinearity equation based on the orientation parameters. i Y i Z i The entire process involves real-time orientation and measurement.

[0103] The equation for the collinearity of the measuring points on the profile is:

[0104]

[0105]

[0106] This embodiment designs a large-scale, three-dimensional spatial control field, roughly the size of the antenna product under test, formed by multiple control points within the overall measurement area of ​​a rapid antenna profile measurement system composed of multiple cameras. Multiple trackers are networked together, and precise calibration of the three-dimensional coordinates of all control points is achieved based on a high-precision ranging method. The rapid profile measurement system simultaneously images the control field with known control point coordinates and the antenna product under test with unknown measurement point coordinates. Based on the principles of single-phase spatial resection and multi-phase forward intersection, the system simultaneously completes two processes: calibrating the extrinsic parameters of the rapid antenna profile measurement system from the control points and calculating the coordinates of unknown points on the antenna profile from the system's extrinsic parameters. This achieves real-time calibration of the rapid antenna profile measurement system. This embodiment employs a multi-camera real-time extrinsic parameter calibration method based on a large-scale, three-dimensional layout of control points. This solves the problems of general extrinsic parameter calibration methods, which involve step-by-step measurement processes, resulting in poor real-time performance, low efficiency, and the inability to avoid the impact of environmental changes such as vibration on calibration accuracy.

[0107] This invention solves the problems of general external parameter calibration methods, such as step-by-step measurement processes, poor real-time performance, low efficiency, and inability to avoid the impact of environmental changes such as vibration on calibration accuracy. The three-dimensional structure and the design of large-scale control points that match the size of the product being measured are adopted in this invention, which solves the problem of insufficient control constraints on the measurement accuracy of three-dimensional, large-size products after absolute orientation is achieved using a one-dimensional, short-length reference ruler during the system calibration process. The method of connecting multiple trackers to measure control points based on laser tracker ranging improves the measurement and calibration accuracy of large-scale three-dimensional control points on site.

[0108] 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 real-time calibration method for a rapid antenna profile measurement system, characterized in that... include: Multiple control points are set up in the area where the antenna under test is located, forming a three-dimensional control field; the antenna profile rapid measurement system is set up above the antenna under test; multiple measuring cameras constitute the antenna profile rapid measurement system. Multiple laser trackers are set at the boundary of the three-dimensional control field. The position and attitude relationship between each laser tracker is obtained by networking multiple laser trackers through directional points. The total number of laser trackers is Q. The directional point is a 1.5-inch angular dipole spherical prism. Several control point setting positions are selected from multiple control point setting positions to set the directional point. Each laser tracker aims and measures the distance between each control point and the center of each laser tracker. A spatial sphere is created, and the precise three-dimensional coordinates of each control point are obtained by intersecting the spatial spheres. The rapid antenna profile measurement system takes photographic images of the control point and the measured marker point of the antenna under test to obtain the image point coordinates of the control point and the image point coordinates of the measured marker point of the antenna under test. Based on the collinearity condition equation of the control points and the preset intrinsic parameters of the measuring camera, the position and attitude of the measuring camera relative to the control field coordinate system are obtained according to the image point coordinates and the precise three-dimensional coordinates of the control points. The three-dimensional coordinates of the measured marker points of the antenna under test are obtained based on the collinearity equation of the surface measurement points and the position and attitude of the measuring camera relative to the control field coordinate system. Multiple control points include multiple ground control points and multiple high-level control points. Among them, multiple ground control points are set up in the ground area corresponding to the area where the antenna under test is located, and multiple high-level control points are set up in the ground area using a bracket support method. The multiple ground control points and multiple high-level control points form a three-dimensional control field.

2. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: In the three-dimensional control field, the length, width, and height of the envelope formed by all control points are equal to the length, width, and height of the area where the antenna under test is located. Each measuring camera's field of view covers ≥3 control points, and there are no common control points between the measuring cameras.

3. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: The control point is a hemispherical structure, with a circular fluorescent target attached to the center of the hemispherical structure; The control point is attached to the magnetic base, and the circular fluorescent target faces the reference surface of the antenna-shaped rapid measurement system.

4. The real-time calibration method for the antenna profile rapid measurement system according to claim 3, characterized in that: The diameter of a circular fluorescent target is obtained using the following formula: ； in, The diameter of the circular fluorescent target. To measure distance, For image pixels, To measure camera pixel size, This refers to the camera's focal length.

5. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: The method of networking multiple laser trackers using orientation points to obtain the position and attitude relationships between each laser tracker includes: Based on the spatial coordinates of the orientation point at the same location in the coordinate system of each laser tracker, the position and attitude relationship between each laser tracker is obtained through joint adjustment calculation.

6. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: The precise three-dimensional coordinates of each control point are obtained using the following formula: …… ； in, Let X be the X coordinate of the Mth control point. Let Y be the Y coordinate of the Mth control point. Let Z be the Z coordinate of the Mth control point. Let M be the distance between the first laser tracker and the Mth control point. The X-coordinate of the center of the second laser tracker in the online measurement coordinate system. The Y-coordinate of the center of the second laser tracker in the online measurement coordinate system. The Z-coordinate of the center of the second laser tracker in the online measurement coordinate system. The distance between the second laser tracker and the Mth control point is... Let X be the center of the Q-th laser tracker in the online measurement coordinate system. Let Y be the center of the Q-th laser tracker in the online measurement coordinate system. Let Z be the center of the Q-th laser tracker in the online measurement coordinate system. Let Q be the distance between the Q-th laser tracker and the M-th control point.

7. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: The collinearity condition equation for control points is obtained by the following formula: ； ； in, Let X be the X coordinate of the Mth control point. Let Y be the Y coordinate of the Mth control point. Let Z be the Z coordinate of the Mth control point. To measure the focal length of the j-th camera, Let the x-coordinate of the j-th measuring camera lens center in the online measurement coordinate system be denoted as . Let the Y-coordinate of the center of the j-th measuring camera lens be in the online measurement coordinate system. Let j be the Z-coordinate of the center of the camera lens in the online measurement coordinate system. , , , , , , , , The nine parameters that form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system, where j is the measurement camera number, For the x-axis deviation of the image point, For the image point y-deviation, Let x be the x-coordinate of the image point. The ordinate of the image point, , and All are radial distortion coefficients. Let the radius be the image point. and All are eccentric distortion parameters. and All of these are image plane distortion parameters.

8. The real-time calibration method for the antenna profile rapid measurement system according to claim 1, characterized in that: The equation for the collinearity of the measuring points on the profile surface is obtained by the following formula: ； ； in, Let X be the X-coordinate of the i-th measured marker point in the online measurement coordinate system. Let be the Y-coordinate of the i-th measured marker point in the online measurement coordinate system. To measure the focal length of the j-th camera, Let the x-coordinate of the j-th measuring camera lens center in the online measurement coordinate system be denoted as . Let the Y-coordinate of the center of the j-th measuring camera lens be in the online measurement coordinate system. Let the Z-coordinate of the center of the j-th measuring camera lens be in the online measurement coordinate system. , , , , , , , , Nine parameters are used to form the rotation transformation matrix between the online measurement coordinate system and the camera's own coordinate system, where i is the measured marker point number, j is the measurement camera number, and so on. For the x-axis deviation of the image point, For the image point y-deviation, Let x be the x-coordinate of the image point. The ordinate of the image point, , and All are radial distortion coefficients. Let the radius be the image point. and All are eccentric distortion parameters. and All of these are image plane distortion parameters.

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